Evolution BIO339 Test 1

Community

(all different species) not involved in a population

Population

(all members of same species) descent with modification (evolution) occurs here as a result of the survival or not of the individuals in a population

Parthenogenetic whiptail lizards

(cannot reproduce sexually; there are diploid sexual populations of whiptails and there also are parthenogenetic species of whiptails; parthenogenetic female whiptails do have to undergo pseudo copulation) - Purely parthenogenetic species = hypothesis is that they wouldn't last as long because the genetic variability is low and wouldn't adapt to environment well - Rotifers are exception - Species of mites where siblings reproduce while still inside mother's digestive tract and then eat the mother upon birth

Variation and Mutation categories of variation C. Genotype-by-environment

(genotype is expressed differently in different environments; similar to but different from induced defense in that this doesn't involve induction during the lifetime, simply a different permanent expression of the genotype depending on environment)

individual

(organism)natural selection selects individual organisms; in particular, the environment directly selects phenotype; heritability means that phenotype is linked to genotype; if body and beak size of finches were not heritable, you would still see those with large beaks survive and those with small beaks die; it just would not lead to evolution, because the next generation would still produce the full range of beak sizes because it would not be heritable

cleptogenesis

(use sperm to active without fertilization and using the genetic material)

evolution

- (in terms of modern synthesis) = change in allele frequencies; frequencies are part of population, so population is affected by evolution - it is the unit of study (not the individual) - Community - Population - Individual

insular gigantism

- = if insects on island where being prey isn't a concern... species evolve to get bigger and if there are advantages to being larger, it will continue to grow

Summary topic 1

- Again, evolution required the trait in question to be heritable - Natural selection must act on existing traits; trait that becomes the adaptation must already exist before evolution can occur; trait cannot be formed because of change; environmental conditions don't cause traits to appear, they just determine which traits are favored that already exist; use antibiotics on bacteria and none have allele for resistance = all of them will die; they will not gain an allele for resistance because the antibiotic was used - Natural selection can take a trait and bring about a new use for it - Exaptation = when an existing trait becomes an adaptation for something different (a new circumstance); feature already existed but evolved a new use - Ex. Radial sesamoid in pandas has enlarged and formed enough of a thumb-like structure that allows them to grip bamboo - Ex. Ostrich wings are not used for flight anymore, but they are used for signaling - Ex. Bird feathers are not unique to birds; many dinosaurs had feathers; feathers evolved for something other than flight, but it was discovered that feathers are very beneficial for flight - Mutations may produce a new product; environmental need doesn't call for a new trait appear, only modifies it - There is randomness in evolution and natural selection - Variation in populations is generated randomly (variations come from mutations, which are random) - Environmental changes are unpredictable/random - Above bullets cause natural selection to occur (which leads to evolutionary change), but natural selection itself is not random, as individuals survive because of certain traits that they have that are selected by nature based on environmental conditions - Natural selection is not random thus evolution itself is not random - Natural selection is not a ladder moving toward perfection Lemark = most important goal was to achieve "perfect form"; organisms must only be "good enough" to survive and reproduce; don't need to be perfect - Trade off between survival and reproduction; two things must happen, survive and reproduce; both of these are things that selection will act; only certain amount of effort that you can put into what it does; must be trade offs; allocations to survival and reproduction; more that goes into survival, the less that goes into reproduction; o Ex. Western mosquito fish = male will produce gonopod using for sexual reproduction; females are attracted to bigger gonopods, so males with bigger gonopods are more likely to reproduce; conversely, gonopods that are too large begin to hinder the fish's ability to swim fast thus lowering the ability for the fish to evade predators; as a result, survival is hindered (trade off) - Natural selection = chooses trait that incurs a better chance of survival; trait doesn't have to be based on the individual being bigger/stronger/more complex - Insular dwarfism = island populations have reduced resources so elephants smaller in size are selected by NS and the population decreases in average size across generations

new genes from noncoding sequences

- Can trace three known cases in humans where a noncoding sequence has begun to produce a product that has become useful; new gene from scratch - DNA not transcribed or translated can sometimes produce products that NS can act on

Natural selection postulates (Darwin's)

- Darwin's notion of evolution through natural selection follows four postulates; if the postulates are true, then evolution must occur; postulates are testable and verifiable; and not assumptions

Testing Darwin's Postulates

- Difficult to find species to study over generations; must match many criteria - Darwin's finches = group of 12-13 species of finches found in the Galapagos Islands evolved from a single species that arrived there 2-3 million years ago

True age of the Earth

- Earth is over 4 billion years old - about 4.5 billion; dated by radioisotope methods; when rock forms, it has a certain ratio of isotopes, it changes over time; change is used to date age; multiple isotopes overlap and tested; old rocks = 4 billion years; - Darwin didn't know true age of the earth; didn't know cytological basis

mole rats and kin selection

- Mole rats are very happy with inbreeding; very successful population despite being highly inbred Whether mating is random or not does not affect allele frequency, so it is not a direct cause of evolution itself. When mating is not random (assertative), it can affect genotype frequencies which then affects phenotypes frequencies, which is what natural selection selects. There is inbreeding when extremely non random mating; inbreeding coefficient → higher number = more inbred; inbreeding depression = decrease in genetic diversity/increase in homozygosity; outbreeding depression → go so far out of the group that you break up successful combinations Mole rats → eusocial mammals; many members do not breed but carry out work tasks; highly inbred so nearly all have same genetics *Kakapo: flightless bird; inbreeding decreases sperm quality (40% of eggs don't hatch); wolverine intro - Inbreeding and genetic drift in small populations are a problem for conservation biology; EX. Florida panther (variety of mountain lion) are reduced to such low numbers that genetic diversity of them became significantly less than other pumas; introduced Texas pumas to help genetic diversity and an increase in heterozygosity increased in the population of Florida panthers

Effect of mutations

- Mutations can be lethal, deleterious, neutral, or beneficial; natural selection normally pushes allele frequencies in a particular direction; if no natural selection on a particular trait, deleterious mutations will accumulate o Neutral genes are subject to genetic drift but not selection - Mutation rate vary among species: virus > bacteria > eukaryotes

Violating assumption 1- Natural selection

- Natural populations very rarely meet all of the HW requirements; certain alleles may but it is still rare - 4 ways of having different allele frequencies within a population - Genetic drift = changes in allele frequencies that are a result of random chance events - Selection eliminates some genotypes that aren't favored and increases the ones that are favored - Selection can very in strength - Raising flies in environment high in alcohol content; an increase in frequency of the allele that metabolized alcohol occurred

Lamarck's theory of the inheritance of acquired characteristics

- Proposed mechanism for evolution; based on selection; his concept turned out to be incorrect; concept "what an organism does in its lifetime to change its body can be passed onto its descendants" o Ex: Giraffe would stretch neck to reach a branch and neck would become longer, which would then be passed onto offspring o Ex: bigger tomatoes made by humans - Wallace and Darwin overlapped; Darwin upper class British; Wallace was from poor background so he had to work to make money to pay for his research; Wallace was co-discoverer of natural selection -Sexual selection is different from natural selection

related genes and multiple copy genes

- Series of duplications can lead to whole family of related genes with different functions - Globulin families arose from duplications and new functions evolving from them - Humans have clusters that occur in many loci and vary in expression and function; - Fetal hemoglobin (result of duplication and modification over time) is expressed prenatally and adult hemoglobin is expressed later; fetal hemoglobin has higher affinity for oxygen - Each globin is a result of a duplication that has occurred in the past

unequal crossing over and reposition

- Sometimes crossing over between homologous chromosomes is done so unevenly and as a result some gametes have extra genes, giving two copies of C - Ex. C is duplicated and is an expressed gene; so mutations can accumulate in duplicated/new C without any effect because still have complete, functional copy of original gene C = duplication mutation - Conserved genes = so important that most variations are selected against; if it's a very important one, it may be useful to have many copies doing the same thing (for instance, genes involved in making rRNA or mRNA); having more copies of genes doing the same thing is beneficial - Creation of new genes involves instances when the duplicated gene doesn't become conserved, but it starts to vary instead

Descent with modification

- Species change over time (microevolution) - Lineages split and diverge (speciation) - New life forms derive from older forms (macroevolution) - All life forms are related (common ancestry) -Earth and life are old

Special Creation

- Species do not change - Lineages do not split - Each species is separately created Each species is independently created - Earth and life are young

selfing

- ability to fertilize oneself; must be hermaphrodite to do this; - Ex. Tapeworm - Ex: California Redwood (tallest trees in the world) is a hexaploid; it can reproduce sexually and vegetative Ex: many fruits are triploids (make bigger bananas)

key points about NS

- acts on an individual; acts on phenotype (thats being selected) - the selection of individuals brings about evolution in a population bc allele frequencies have changed -________ precedes evolution (ex: finches results of evolution appear in generation 2, after the changes/selections occured in generation 1) - *evolution is always one generation behind environmental change*

transitions

- change from one purine (Adenine and Guanine) to another purine or pyrimidine (Thymine, Cytosine, and Uracil) to another pyrimidine; one mutation is altered

transversions

- change from purine to pyrimidine or vice versa - Pyrimidines are smaller in size than purines; pyrimidine have 1 ring/ purines have 2 rings - Transitions outnumber transversions 2:1 - Transversions are more disruptive; sickle cell trait (hemoglobin) is caused by = GAG → GTG; proves that a single base pair substitution can be significant - Twice as many transitions occur than transversions

descent with modification

- definition of evolution; organisms today are descended from ancestors who were different and that there are relationships among organisms that can be shown on a map/tree; essentially change across generations; there are relationships between two groups of organisms

Beneficial mutations

- increase probability of survival and reproduction - Varies with environment; an insect with/without a mutation to resist insecticide doesn't affect the individual unless insecticide is applied to its environment -Most important to evolution

3rd postulate

- it is possible for populations to go beyond the limits of their environment; more offspring are produced/born than survive and reproduce; many die without leaving descendants - Why don't individuals survive and reproduce? Mixture of bad luck (randomness) and selection; survival isn't always random; selection can be accomplished by nature; some individuals in heritable variation have characteristics that made them more likely to survive - Environment determines what traits are heritable C. More offspring produced than survive (differential reproductive success)

Stotting

- leaping into the air when a predator is seen (springbok aka the jumping deer does this) -This lets the predator know that "Hey I see you, come at me bruh" rather than "Save me pls" - Ex: Cellular slime molds; most of life is spent as a free living amoeba; chemicals cause Amoebas to come together and form stalk with a top; those that form a stalk do not leave descendants

Loss of function

- lethal: looking for things that will change overtime

direct observation of change

- modern birds= no teeth, no tails but do have tail feathers, no claws on wings, have feathers and fly - fossils found of flying birds that do have teeth and claws and tails - modern birds still have genes for teeth a. Turtles have unique placement of shoulder blade; is found under the rib; most amniotes (reptiles birds mammals) have the shoulder blade over the rib i. Turtle fossils have been found that are transitional state of the rib placement b. Harder to study elephants and tree evolution due to long lifespans i. Tusks on modern elephants can be bad and they have developed without them over history ii. Deer have smaller antlers because hunters go after deer with large antler spreads

homology of molecular characters

- more closely related organisms are = more similar organisms are in number of chromosomes, amino acid sequences, sequences of nucleotides in DNA A. Levels - # of chromosomes, specific genes, codon, nucleotide - Apes (chimpanzees, gorillas, orangutan) have 48 chromosomes; humans have 46; humans have a chromosome that fused together from apes; point evolution after split from other chimps to humans, two chromosomes fused; thus, humans have 46 chromosomes; can tell exactly which fused bc you can see the corresponding set of genes in chimpanzees, gorillas, orangutan is in two chromosomes but is in only one chromosomes in humans - Can look at particular genes for amino acid sequences to show relationships - Can also look at sequence of nucleotides; very powerful - DNA; must align DNA strands correctly to compare B. Example - Species A: AAG/AAA/CGC/GGC Species B: AAG/AAA/- -C/GGC - Various levels of molecular - Can be concluded that B had some sort of deletion at some point - Indicates that third C in CGC and lone C are homologous to each other - Need much longer sequence to prove relation in real situations

examples of convergent evolution

- pitcher plants catch insects with their deep pool - ex: whale and shark share similar characteristics (different look due to environment) - birds and insects dont have common ancestor but both have wings to fly

Darwins Theory of Evolution Through Natural Selection

- relation through natural selection and evolution; artificial selection - theory of evolution= not about whether evolution occurs; the existence of evolution is not a thoery about whether it occurs, but it is an observation; theory of evolution is about how/why evolution occurs; theory of evolution is natural selection

Reanneal

- repair of broken chromosomes; inversion occurs when portion of chromosome is repaired and put back in reverse which causes a segment to be read backwards; if repair is completed successfully, there is no inversion because original form is reformed - Inversions can switch around whole genes that end up in an area that is converted which doesn't crossover

4th postulate

- those that survive and reproduce tend to be those that have traits that are favored by the environment "survival of the fittest"; favored traits allow individuals with those traits to survive and produce and pass on traits to offspring C. Variations favored by environment have greater survival ("survival of the fittest") The trait already existed in the population, but if it was beneficial in a changing environment, then it was favored, thus the individuals had more mates/offspring and the trait was carried on.

altruism

- to show this, when an individual lowers its prospects to survival and reproduction to help another organism(one that is NOT related to the individual) survive and reproduce NOT Ex(s): Black footed prairie dog = whistles to give warning of a hawk; only prairie dogs that hear the whistles are those nearby, which are nearly always the signaler's relative - Traditionally, warning calls are for the individual's own benefit or its relatives

Adaptive traits

- trait that increases the ability of the individual to survive and reproduce (adaptive trait=adaptation (same thing)) -trait that increases likelihood of survival and reproduction; adaptive traits increase fitness; individuals that have them are more likely to survive and reproduce

fixity of species

- under this view, the world is often viewed as relatively young; immutable (species will change little or not at all) - no concept of relationship or linkage to one another. James Ussher determined earth was created at 6pm on october 22, 4004 BC. 6,022 years old

Fossils

-Cuvier: anatomist that showed that _______ are generally of species that are now extinct; shows world of organisms that is extinct now - direct evidence of past life

Strength of selectioin

-If negative/positive will determine the strength II. Very strong selection = more rapid evolutionary change is seen III. Very weak selection = change is produced over time; can still cause a big change in allele frequency

Ingroups and Outgroups (methods to make a tree)

-If you want to look at relationships among a group of species, you need to look at area of interest -Only way to tell is if it's a pleisiomorphy -Critical to have DNA aligned; if not, all DNA is mixed up -Reeversal is possible -2 problem that you can have are there are 4 possible character states (nitrogenous bases) and reversal of DNA is possible -Must use large data sets -Nuetral sequences are favored because of slight selection Would have to have outgroup (something that is not a member of the ingroup, but it has to be reasonably/closely related; from the sister taxon) for cats could be some other carnivore or for bears use a wolf; if you don't do this, can't root tree and make a good comparison, because then can say traits in common are pleisomorphies (if both have spur on third vertebra, then that character will not distinguish the in group from the out group)

mechanism of mutation

-Mendalian genetics- Darwin lived about the same time as mendel but didnt understand genetics- Molecular genetics (DNA)

ontogeny

-developmental biology - relates to the development of organisms; even before the idea of evolution and Darwin, it was discovered that vertebrate embryos of different organisms resemble each other - Darwin suggested that the reason for this occurrence is common ancestry thus similiar patterns of development; earlier in embryonic dev. = more similar organisms will be; later in dev. differences become apparrent. -"ontogeny recapitulates phylogeny"-- embryonic developmental history is a mirror of evolutionary history; earlier in dev. = more similar

Transitional forms

-fossils with characteristics that are intermediate btw an older form and a later/ modern form - clams and birds are animals that have strong fossil records and can have their history traced back through their fossils

Principle of Parsimony(methods to make tree)

-not infallible; philosophical, logical principles for deciding between alternatives when data don't make it certain and need to come up with answer; choose simplest solution/explanation that fits facts when don't have adequate evidence; can have a reversal of trait as seen with the cats going from s pots to uniform coat -The preferred tree is the one that has the fewest branching points; does not mean it is the correct one, but that it is the simplest (could have complicated evolutionary history, just fewer branches) Used with DNA sequence approach -Problem with possible branching patterns increases greatly with the number of taxa; some are pretty unlikely, and characters can distinguish them

polytomy

-unresolved node -using data given, cannot tell what the exact branching pattern is; data cannot prove what pattern is correct; split of branch into more than 2 areas

Relation of evolution and natural selection; artificial selection

. Natural selection (theory of evolution) o Purpose: survive and reproduce o Cause of evolution; (evolution = descent with modification) 3. Evolution is an observation; natural selection is an explanation of why evolution occurs Is it a trait or just luck that allows species to survive? Survivors were those who had the largest beaks. Factors: Drought: less food Seeds that survived- harder seeds Scarce food larger birds with larger beaks are able to defend the food sources Survivors tended to have bigger beaks When the drought was over and softer seeds were more abundant, smaller beaks were favored again. Larger beaks were not advantageous for eating softer, smaller seeds. Agent of selection (seed size) and individual lives or dies, reproduces/ does not. Must have next generation to observe what is favorable and heritable.

Basis of NS

1. Natural Selection acts on individuals but its consequences occur in popluations 2. Natural Selection acts on phenotypes but evolution consists of changes in allele frequency 3. Natural Selection is not forward looking 4. Although selection acts on existing traits, new traits can evolve 5. Natural Selection does not lead to perfection 6. Natural Selection is non random, but NOT progressive 7. Fitness is not Circular* (didn't really go over) 8. Selection acts on individuals, not for the good of species a. Basically altruism is not real

exaptation

1. When a vestigial characteristic on an organism forms new functions 2. Examples a. Ostriches = vestigial wings that aren't used for flying but are used to signal other ostriches or protect their children; vestigial structures can eventually disappear completely b. Royal Python snakes have vestigial hind limbs spurs; used in sexual reproduction but no longer function as legs as in prior generations Pandas having a "thumb" to help them grasp bamboo

Genetic alignment (DNA Method)

3 species with the following homologous sequence, but no out-group: 1: AAC/GGG/TAC/CCT 2: AAC/ GGA/ TAC/ CCT 3: AAG/ GGG/ CCT Now let's add two out-group species AAG/AGG/TAT/CCT TAG/AGG/TAT/CCA New out-group: AAG/GGG/AAT/CCG ^Need to be homologous to each other Can infer from this^ that Species 1+2 originally started as G and are apomorphies Most parsimonius tree (shortest amount of branches) is: Species 1/2/3 (and not O1+2) When things are the same between in/out-group= basal group In-groups: S1/2/3

Paraphyletic

: doesn't include all common ancestors; or descendants

Sister taxon/outgroup

: whichever is most closely is related to the group you are studying but not in the group -If same trait: pleisiomorphy So for vertebrae, will use invertebrate like lancelet so use that as out-group and will be distinguishing character, but notochords are very primitive and are present in both inverts and extraverts so is not a defining character

Directional selection

= some measurement of fitness and range of variability in the alleles; one end is favored and the other end is selected against; example → giraffes with long necks vs short necks; a difference is selected, can be bigger, smaller, darker, lighter, etc.; longer beaks were favoured more than the shorter beaks that were selected against; shows descent with modification; directional selection → change involves some clear cut change to it; one end is favored and the other end is favored against

Hardy-Weinberg mathematics

A. Theory a. Look at particular gene and see frequency of A and a B. Example - A1 → p = frequency of A1 - A2 → q = frequency of A2 - p + q = 1 - Distribution of genotypes in next generation = (p + q)2 - p2 + 2pq + q2 = 1 - Can use this to determine genotype frequencies (probability) in next generations: A1A1 = p2 A2A2 = q2 A1A2 = 2pq - Can we show allele frequencies of the next generation? o A1 p2 gametes; all of which are A1 o A1A2 2pq gametes; ½ of which are A1 o Frequency of A1 in next generation → ▪ p2 + ½(2pq) = p2 + pq ▪ P2 + pq = p2 + p(1-p) = p2 + p - p2 = p therefore, if four assumptions are met, there is no change in allele frequencies from one generation to the next therefore no evolution A1A2 X A1A2 → (next generation) A1A1 = p2 = 0.72 = 0.49 (AA) A1A2 = 2pq = 2 x 0.3 x 0.7 = 0.42 (Aa) A2A2 = q2 = 0.32 = 0.09 (aa) 0.09+0.42+0.49= 1.0 Frequency of A1 = p2 + 2pq = 0.492 + (0.7)(1-0.7) = 0.7 = DOES NOT CHANGE A1 = 0.3 A2 = 0.7 -4 forces for evolutionary change: mutation, migration, selection, and genetic drift ß

selfing

A. most extreme type of inbreeding; sexual species that fertilize themselves (example tapeworms, some plants); not asexual because asexual doesn't mate with anyone; if pure selfing → frequency of heterozygotes in one generation drops by 50%; thus doesn't take long to eliminate heterozygotes (either becoming AA or aa); important to note that allele frequencies are staying the same, thus evolution is not occurring

genotype frequency

AA (0.5) Aa (0.3) aa (0.2) needs to add up to 1.0

pleisomorphy

An evolutionary trait that is homologous within a particular group of organisms but is not unique to members of that group; not useful because no distinguishing- Basal

ex. concerted evolution of mRNA

Concerted evolution is a process that may explain the observation that paralogous genes within one species are more closely related to each other than to members of the same gene family in another species 2. Globin gene family -Come from multiple divisions in family; occur in multiple locations; expressed at different times

Cytological basis of heredity

Darwin didnt know what DNA and genes are; what heredity is and how things are inherited; he knew that new variations appeared, but he didnt know what a mutation is or how they occured

violating assumption 4- genetic drift

Definition = random variation in allele frequencies across generations - Theoretically, genetic drift/random events are only force acting on allele, fixation (1.0) or elimination/loss (0.0) would occur overtime given enough generations - This would not happen in populations infinite in size - In real terms, genetic drift is only effective in small populations (less than 50-100 individuals) II. Fixation and loss of heterozygosity III. Population size - Large populations show minor fluctuation from genetic drift; better with small populations - Small drop in heterozygosity towards homozygosity in large populations because not much fixation is going on - Smaller population = more likely allele will become 1.0 or 0.0 through genetic drift **if nothing else is selecting it** - When population is small, genetic drift normally decreases genetic diversity; leads to decrease in heterozygosity - 107 small populations of flies, all with frequency for bw75=0.5; only thing affecting allele was genetic drift; followed flies for 19 generations; more alleles became 0.0 or 1.0 over time (fig. 7-16 page 32) IV. Founder effect situation where effects of genetic drift can be seen; - Small population - Where colonization occurs and new populations are formed - A few individuals of a big population start a new colony and won't be reinforced by migration later (ie single pregnant female) - "Who makes it" is random, very little selection involved; represent small part of original population - Founder populations have extremely low genetic diversity; few rare alleles; and it is likely to drift to fixation or loss - If population grows, genetic diversity can increase by mutations, but it takes a long time V. Bottleneck effect situation where effects of genetic drift can be seen; - Small population - Population undergoes a drastic reduction in size; who survives is dependent on who was luckier; survival was more of a random draw - Small number of individuals with low genetic diversity - Even if numbers are recovered, genetic diversity is still low - Northern elephant seal → increased from 30 to 100,000's; low genetic diversity

evolution does not achieve perfection

Ex: Panda I. They have something like a thumb, but it's an exaptation; picked up the function to help them grasp bamboo - Survival Versus Producing Offspring: there needs to be a tradeoff Males have a really long fin (females like the longer ones→ male gets selected → more sex); if too log, it can interfere with their swimming

Variation and mutation categories of variation B. environmental

Ex: inducible defense in water flea - Water fleas are small crustaceans common in marine/freshwater - Interest is that these organisms can live with or without spines; inducible defense - Individuals with spines and individuals without spines don't have to vary genetically - Not a difference in organisms has or don't have alleles for spines - Synthesis of proteins that make the spine in a water flea increases after the water flea detects the chemicals of its predator (midges) thus water fleas grow spines only when midges are around; and the proteins aren't synthesized if the chemical is not detected - Whether an individual has a spine or not is not passed onto the next generation; merely induced by the presence of a predator thus induced defense; genotype allows for flexibility in expression Ex: you becoming tan

Leks

Females choose males that impress them most (3 types due to inversion) 1. Lekking* most common 2. Satelite 3. Looks like female -Presence of inversions invited supergenes (determines morphological traits)

1) no selection 2) no mutation 3) closed population/no migration 4) infinite size *5)panmixia[not assumption required for HW] random mating*

HW Equilibrium Assumptions

I. NS didn't cause it to happen; worked on something already present II. New genes appear through mutation

How do new traits evolve?

Uniformitarianism

Hutton said the geological prophecies observed today, are the same from the past - uniformity principle= natural processes that work today are the same ones that existed in the past -ex) speed of light today is the same from the past

Molecular clocks (method to make a tree)

I. More divergent as time goes on; rates can be predictable I. If start out similar then diverge... can predict II. Fossils are evidence that the species split; can use to determine mutation rate

goals of phylogeny

I. To construct evolutionary histories (origin, ancestors, etc.) II. Every phylogeny is a hypothesis (subject to testing I. Can be rejected with new data II. Characters in cladistics = cladistics is the most common method used today

bottleneck effect

IV. situation where effects of genetic drift can be seen; - Small population - Population undergoes a drastic reduction in size; who survives is dependent on who was luckier; survival was more of a random draw - Small number of individuals with low genetic diversity - Even if numbers are recovered, genetic diversity is still low - Northern elephant seal → increased from 30 to 100,000's; low genetic diversity

founder effect

IV. situation where effects of genetic drift can be seen; - Small population - Where colonization occurs and new populations are formed - A few individuals of a big population start a new colony and won't be reinforced by migration later (ie single pregnant female) - "Who makes it" is random, very little selection involved; represent small part of original population - Founder populations have extremely low genetic diversity; few rare alleles; and it is likely to drift to fixation or loss - If population grows, genetic diversity can increase by mutations, but it takes a long time

No, actually a response to the environment in the previous generation; offspring of the surviving individuals have a trait or adaptation but they're actually adapted to the conditions of the parental generation; in essence, evolution is a result of natural selection, and it is always a generation behind environmental change; adaptations are toward the past

Is natural selection forward looking?

Homology example

Mammalian middle ear; bones of middle ear: malleus, incus, stapes; will focus on stapes - Stapes evolved from hyomandibula bone - Function of stapes = transmit sound - Transitions (changes) lead hyomandibula to develop into stapes (process called acceptation) - Fossil histories show transitions in this bone; also embryonic development shows that the hyomandibula and stapes develop from the same gill arch in mammals and fish A. Current condition B. Ancestral condition & transformational sequence C. Homology between hyomandibula and stapes 1. Hyomandibula in contemporary fish - Function of hyomandibula in modern fish = involved with breathing; moves and ventilates the gills of crossopterygias and the lungs in lung fish 2. Hyomandibula in crossopterygians 3. Early tetrapod: Acanthostega stapes - Stapes replaced hyomandibula that is connected to skull so that it is now used to transmit sound; development of tympanic membrane and other ear structures in mammals provide further evidence of the hyomandibula transitioning into the stapes; hyomandibula exapted to stapes thus function of breathing to hearing, respectively 4. Preadaptation III. Other examples of homology A. Articular and quadrate vs. malleus and incus; articular → malleus; quadrate → incus B. Giraffe and whale neck vertebrae (long neck vs. short neck) - Have same number of vertebrae, 7; shape of bones is different C. Bryozoan and brachiopod lophophores - Homologous relationship between two phyla of marine organisms D. Molluscan foot - Homologous characters but have different functions; foot does different things in different groups of molluscs; snails crawl on it, clams dig with it, squids develop tentacles from it E. Animals and fungi (animals and fungi are more closely related to each other than either is to plants) 1. Genetic code and gene sequences - Both have same variation in genetic code for mitochondria (animals and fungi) - Common gene sequences (animals and fungi) - Have chitin (animals and fungi) 2. Metabolic pathways are similar (animals and fungi); both use glycogen (unlike starch in plants)

violating assumption 3- Gene flow

Migration = movement of alleles between populations - Bringing new alleles into a population changes allele frequencies II. One-island model - Has to be ability to move between them (island and continent) - Island population is much smaller than mainland population - Gene flow is possible; could possibly produce new allele - Disproportionate amount coming from mainland to small population on island Going to small island will increase allele frequency - Mainland and island have 1.0 allele starting off - Mainland island A2 1.0 A1 1.0 20% immigrant population from mainland (A2) to island (A1); allele frequencies changed A1 0.8 A2 0.2 evolution by definition - After one generation of mating, HWE achieved unless more migration occurs - Eventually populations will become similar; island becomes very much like the mainland Evolution = change in allele frequencies from one generation to another Natural selection = one cause of natural selection

White throated sparrow

Not inverted: submissive, duty of parental care Inverted: extremely aggressive -Both exist because they can have offspring SPARROW'S SUPERGENE IS LARGER THAN RUFF

genetic diversity often high

Populations have allele frequencies I. Can have homo/heterozygous II. Measuring it: percentage of polymorphic loci I. Location on gene is called locus (hence, loki) III. Another measurement is mean heterozygosity

accumulation of deleterious mutations

Results in non-functional genes→ reduce natural selection

homoloplasy or analogy

Three organisms have opposable thumbs: -chimpanzee and human = homology -opposum and human= homoplasy Three organisms have fingerprints - chimps and human = homology - koala and human = homoplasy

vestigial structures

a. Darwin demonstrated this with evolution b. ______________ were useful at one point, but not anymore i. Examples 1. Eyes on cave animals a. Don't need eyes because of no light so animals will start to develop without them 2. Pelvis bone on whales 3. Kiwi Bird: completely ________ wings (maybe used to fly) 4. Arrector pili muscle - causes goose bumps but originally meant to erect hair = structure that is reduced from its ancestral condition; may not be useless but it is no longer useful in its original form. 5. Ancestral whales had fully developed limbs a. Transitional fossils of whales had hind limbs that protruded but were vestigial and not functional b. Modern day whales have vestigial hind bones but no hind limbs

Fitness

ability of an individual to survive and reproduce in the current environment

gene duplication

adds extra copies of a gene to a chromosome

acclimations

adjustments that individuals make from conditions in the environment (ex: tanning) -Ex: if fish is able to adjust, the muscles adjust to range of temperature -Ex: if leaves take advantage of light, they'll be facing the sun -Pattern of phenotypic plasticity is the rection norm (interchangeable)

concerted evolution

after gene evolution, both are continuing to do the same function; having more is good

taxon

all descendants of a common ancestor; determined by monophyletic group

gene pool

all the genetic information from all the genetic members; more likely to populate within each species

Apomorphy:

also called derived what happens at the transition (shared derived and shared primitive); Apo= to move away from; transitions show apomorphies where there is divergence in a lineage, character change; trait that is different from an ancestor; shared with only itself (homologous)

gene inversion

another way to get new sequences that aren't simply point mutations; involve more significant changes; often deleterious but sometimes produce a new gene; inversions form when chromosomes break at two places and are incorrectly joined back together occur when chromosomes break; take genes and place in reverse order; caused by ionizing radiation

synapomorphy

apomorphy with share derived characteristic; this is shared between the two and the most recent common ancestor

Neutral theory

at the molecular level most evolutionary changes and most of the variation within and between species is not caused by natural selection but by genetic drift of mutant alleles that are neutral. -Don't want something under strong selection because they won't change

macroevolution

big scale; slight genetic/ evolutionary change, usually in morphology; typically refers to the evolution of differences among populations that would warrant their placement in different genera of higher level taxa; novel forms of life can derive from earlier forms

population

btw the community and individual

No, bc NS has no idea about what the future will be like, it will act only on existing traits

can populations adapt to future generations

Microevolution

change through time; changes in gene frequencies and trait distributions that occur within populations and species

close relatives

closer relative= more similar= inbreeding increases

modern synthesis (neo-darwinism)

combination of molecular and mendalian genetics and evolution introduced by Theodore A

special creation

dominant view in darwins time and is todays typical christian view - idea the there isnt any evolution or nothing significant; rather, different organisms/ species were created and dont change signifiicantly over time and dont have branching patterns over time; therefore, it is not possible to say that different species are related to each other under this view

neutral mutations

don't have an effect on the probability of survival and reproduction; functions equally well

descent with modification

evolution occurs when allele frequencies change over generations Genotype frequency for diploid organism = Aa, AA, aa; change in genotype frequency itself is not a sign of evolution in itself; only allele frequency change constitutes evolution - What can change allele frequency? Best to think of it as "What would have to be true for allele frequencies not to change?" (null model) leads to HW equilibrium concept

antibiotics

evolution through natural selection of resistance; eventually become ineffective - death due to antibioitic resistance is increasing (like in the US) ▪ White tail deer - tendency of antlers to be smaller over time through generations; selective pressure because hunters choose deer with bigger horns, reducing population of deer with big antlers ▪ Fossils = best evidence of evolution; critical; scientific evidence that became popular in 1700's; Thomas Jefferson collected fossils

cladogenesis

evolution with branching of speciation If have fossil history, can distinguish the trees, but often they are not available, but will still draw up a tree so use comparative tree If no ancestor to compare an individual to, we must have an in group: group that you're considering; looking at relationship among them

peppered moth

ex of directional selection; Industrial melanism = species of moth Morphs of moths = different expression of melanin pattern; but same species (same batch of eggs will form both types; moths forage during the nighttime; therefore, the moth wants to be not seen during the day; so when there is a lot a lichen, there is a preference for the peppered moth; during the industrial evolution, coal burning caused lichen to die and tree bark to darken, so dark moths were favored

allele frequency

ex: 50 diploids 100 alleles 0.5 = allele frequency

hitchhiking

example: Allele z increases in frequency bc of selection acting on nearby, closely linked gene

pleisomorphy

feathers are a _____ to birds.... reptiles comes from birds

new genes

formation of ____ gives natural selection a wider scope of things to work with

etic

forming a taxon

super genes

genes inherited as a group -groups of genes that are inseparable and are acted on as a unit because they no longer separate during crossing over

divergent evolution

has starting point but changes over time

Symplesiomorphy

homology but doesn't include others; doesn't tell us anything useful; shared pleisiomorphy

phenotype plasticity

how it is expressed can vary depending on environmental conditions Single genotype will be expressed in different phenotypes depending on environments Ex. Orange Sulphur butterfly (seasonal polyphenism) - Same genotype in different generations will be expressed differently - Warmer environments give one phenotype (smaller portion of wings is black/dark) - Colder environments give another phenotype (larger portion of wing is black/dark)

Comparative method

humming birds have beaks; usually strong correlation between the length of beak and how deep the bird's beak must enter flowers to get nectar; accordingly, hummingbirds with very long beaks probably must attain nectar from flowers that are very deep; difficult to trace history of traits; can only infer information from comparisons of existing/living species with the current traits; it would be ideal to analyze the trait over time -- Must know origin (what is evolved from; its ancestral condition) of trait and how the trait was changed/transformed/ what transitions did it go through; fossil histories provide this information

Pseudogenes

in many cases, the new copy is non-functional (lacks regulatory sequences that cause it to be transcribed)

inbreeding

inbreeding coefficient: bigger number = more inbreeding

inbreeding depression

increase in homozygous; more homozygous = more likely to see negative, recessive alleles expressed; mortality rates increase with this; less reproductive success the more inbred mates are; example is when inbred eggs don't hatch

transition

indicate some change of characteristic;node change

1st postulate

individuals in a population vary in their traits (different from each other) A. Individuals in populations vary

-No, mutations are random, natural selection is not random - Not natural selection nor traits that get passed onto future generations - Progressive: moving towards a goal (species more towards perfection) - Evolution is always one generation behind environment.

is evolution random?

extinct (circle on the point)

lines can end: which means that branch went________

extant

living today not extinct *can* show time by using the length of the branch

Cladistics

looks at branching patterns of diagrams and uncovers them through particular methods; dominant method

deleterious mutations

lowers probability of survival and reproduction but not necessarily lethal - These can be lethal mutations = organism will die; many of these are "loss of function" mutations

outbreeding depression

mate with individuals that are too different; example, individuals with generations from equator have darker skin and individuals from north pole have fair skin;

violating assumption 5-nonrandom mating

mating does not change allele frequencies in itself; may see a change is heterozygotes/homozygotes but not allele frequencies; does change and alter genotype frequencies (if mating is not random, genotype frequencies will not be what the HWE predicted); deals with relatives - In sexual organisms, mating that is not random doesn't in itself cause evolution because it doesn't change allele frequency; BUT non random mating can change the HWE predicted genotype frequencies; genotype determine phenotypes, thus genotypes alter phenotypes frequencies; natural selection acts on phenotypes; thus, varying through sexual reproduction/non random mating does have evolutionary effect because selection can act on new phenotypes, but it doesn't directly cause evolution itself because it doesn't alter allele frequencies - Inbreeding is not random; individual is more likely to mate with kin/relative; inbreeding decreases heterozygosity and genetic diversity because more homozygotes are created I. Is it a direct agent of evolution?

5)panmixia

means random mating; aka non-assortative (no selection in mating) - only secual; not realistic; if mating isn't random -allele frequencies won't predict genotypic frequencies

mutation rate

mutations are random events, as they are unpredictable; do not occur because they are needed; doesn't mean that the rate can't vary; higher rate = increase in mutations - Rate of mutation = how often mutations occur; varies across species; mutation rate can be affected by things like radiation and other environmental factors; viruses = high mutation rates - Mutation rates can vary among species and males and females; mean rate of mutation in humans (don't memorize) = 1.2 x 10-8 per base per generation pair; rate is 3-4 times greater in males than females; in chimpanzees, male rate is 7-8 times higher than females -Can differ within species - Generally, more variation does allow populations to survive more effectively than environments change - Genetic variation does tend to be very high - Measures of genetic diversity - Percentage of polymorphic loci - More polymorphic genes in a population = more variation - Locus = gene location; polymorphic = more than one allele - Possible for gene to have one allele and greater than one - Mean heterozygosity (measuremtn of heterozyosity) *More heterozygosity= more genetically variable - For average individual in population, "What percentage of that person's genes is heterozygous?" - More inbred = decrease heterozygosity Theoretically, variation was once thought to be low because amino acid sequencing was not understood, so assumptions could only be made on external features/structural characteristicsII.Allele frequency

2) no mutation

mutations change allele frequencies so can't occur

violating assumption 2-mutation

new alleles and in some case new genes form from mutations; formation of mutation by itself will change allele frequency; generally very small effect I. New alleles II. How much effect on allele frequencies? - Mutations provide raw material for natural selection - Mutations are important to introducing variability, but they don't change allele frequencies very much itself -Created stock of fruit flies with extremely low genetic diversity/variation (highly inbred; for 100 generations only bred siblings) - Unstressed lines were maintained for another 30 generations in environments without salt - Stressed lines were maintained for another 30 generations in environments with salt - Salt stressed; inbred would die instantly if exposed to 5% salt - Salt stressed lines did become more resistant to salt over time by result of a mutation; some cases the flies survived 4-5% salt - Natural selection acted on salt tolerance mutation

polyphyletic

no common descendants recognized → homoplasies lead to phylogenetic groupings

1) no selection

no genotype/allele has any advantage over any other; who survives and who doesn't is not result of being favored by environment

3) closed population/no migration

no one enters and on one leaves; no migration - aka closed population

Disruptive selection

not described as often; fewer examples; selection that favors either end but not the middle; selection against the mean and in favor of the extremes; overtime, this results in a bimodal distribution (two peaks) because the middle range is selected against A. Cactus spines → imagine pecari tajacu and parasites are gone and tourists are the main selection force; they pick "prettier" cactus flowers, so ones with few spines won't be picked; alternatively, cactuses with too many spines won't be picked because they are harmful to the pickers; so selection is a against the middle ground, thus two peaks B. Black-bellied Seedcracker - bimodal distribution of beak size; seed distribution is cause; there are larger, tougher seeds and smaller, softer seeds but no intermediate size seeds; so selection is against the intermediate sized beaks

Homoplasy

not similar because they are related; rather, structures evolve to form simlar characteristics because they do the same thing -_________= evolve to be similar; dont share ancestry -ex) flagella have evolved at least three different times; bacteria have flagella, many eukaryotic organisms have flagella, and Archaens have flagella; structres aren't related across species, but evolved to form similar characteristics

premature stops

not synonymous; will reduce size of polypeptide product to some extent; importance depends on where stoppage occurs

4) infinite size

not tiny: large- something over 100 [larger is better]

reversal

occurs in DNA if over course of time in part place an A became a G and the again to an A -never will be possible to detect; we know eyes evolved in humans, and some cave fish have no eyes, this is a reversal; want characters to be independent of each other (i.e. beak depth and width) a change in one does not affect the other

Phylogeny

origin of groups; phylogeny means groups of species, comes from Greek word meaning "tribes," and it is the evolutionary history of groups; showing who evolved from whom and what is related

cactus spines

pecari tajacu favors plants without spines; so the population of plants with more spines is increased if the population of pecari tajacu is high

Phylogeny

phyo refers to groups of species (mammals, gofer, plants) comes from Greek word meaning tribes; so this is the evolutionary history of groups Cladistics: tries to look at the branching patterns; Greek word meaning a branch; try to uncover the patterns; when phylogenetic tree is done using cladistics, it is called a cladogram Any statement of relationship if a hypothesis: humans more closely related to chimps than gofer is a hypothesis; some are very well established, others are not, thus differences of opinion comes into play Cladistic methods: prefer to use traits only that are heritable -Those can be anatomy, behaviour, physiology, and/or AA and DNA sequences; they must be homologous (forelimbs) resemble each other because they have a common ancestor, the difficulty is knowing if it is homologous or homoplasy -Not possible to be sure you've eliminated homoplasy, so use as many traits as possible, so you minimize the number of traits that will be due to homoplasy

Artificial selection

plant and animal breeding (done by humans) -Not a random process; done by humans (as Darwin would say); not caused by nature -Ex: dogs are descended from wolves and {people would select} dogs with desirable characteristics for breeding which would result in modification over generation. Little runts were bred together, and over the years you got Chihuahuas from wolves -Ex: many vegetables descended from wild mustard plant; corn plants with bigger kernels were chosen to be planted and evolved into plants with bigger kernels

insular dwarfism

population on island where resources are scarce → species will evolve to get smaller over time to accommodate for limited resources; smaller tiger on small island

polyploidization

process of becoming a polyploid; it is a mutation that changes ploidy by adding sets of chromosomes; polyploid = 3n (triploid), 4n, 5n, etc. (haploid = n and diploid = 2n) - Important because it can result in instant creation of new species over a single generation; particularly common in plants; polyploidy offspring constitute a new species - Ploidy = number of sets of chromosomes (Ex. diploid/haploid); change in chromosome number is a mutation - Can occur by two diploid gametes combining; if both egg and sperm are diploid, a gamete can become a viable tetraploid zygote in some cases (more common in plants); result of mistakes in meiosis; commonly involves nondisjunction

Mutations

provide raw material for natural selection; creates variation; variation can be heritable and not heritable (only heritable variation can be acted on by evolution); genetic variation = second postulate; genotype expresses the phenotype

geology

provides aspects about the age of the earth

Norm of Reaction

range/all of the ways that a genotype can be expressed

adaptation

results of natural selection; trait that increases fitness; makes an individual more likely to survive. Ex. Longer necks in giraffes made them more likely to survive because they could reach more food, allowing longer necked giraffes more likely to survive and reproduce which made longer necks an adaptation; adaptions follow from natural selection; fitness is the ability to survive and leave descendants - Not all traits are adaptive; not all traits have to evolve only through natural selection; o Ex. R/L thumb on top when hands are clasped, and whether pinky fingers converge or come together when lined against one another; these are not likely to have been adaptions, as they don't incur a significant survival advantage - However, most of the modification that we view is driven by adaptions; natural selection is not random; individuals survive because they have an advantage; the environment/nature chooses what survives (what is favored and what isn't; advantageous traits don't guarantee survival but do make it more likely that such individuals will survive and reproduce; basis of natural selection)

Sedimentary rock

rock that forms in layers from aquatic dirt that gets put down in layers and forms rock; years of build up of mud and decay; rate of sedimentation was observed over decades (50 years) by geologists and used to estimate and relate the chronological sequence of sedimentary rock formations; generally deeper an organism is, the older it is; this principle gave a chronological sequence a. Origin of the geological time scale b. This meant that they could come up with an age of the planet (guessed 100 billion y/o) c. Kelvin guess 98 million y/o

stabilizing selection

selection chooses the middle ground; selection is against the extreme; probably due to the environment not changing much, ex) a. Cactus spines i. Not too many spines and not too few ii. pecari tajacu predation favors/selects plants with more spines; conversely, parasitic fly that lays eggs inside spines become parasites of cactus; so selection is in favor of plants with fewer spines, thus two selection pressures; stabilizing selection chooses point in the middle that best balances the two selections B. Human birth weight and Sociable Weaver = average birth weight remains constant due to two selection pressures; if too large: baby cannot pass through birth canal, and the more resources it takes from the mother; if too small: underdevelopment aka lack of viability; thus two selective pressures stabilize birth weights - Sociable Weaver - build big communal nests and live together in the nest; bigger birds are favored in the nest; but outside the nest smaller birds are favored because predators choose bigger birds C. Heterozygote superiority - Sickle cell anemia, cystic fibrosis -Stabilizing because its selecting against the normal and sickle cell anemia - Sickling allele HS HN Heterozygote superiority HSHS → sickle cell anemia; resistant to malaria HNHS → some/slight sickling but no serious problems; resistant to malaria; thus increased fitness in environments where malaria is a common factor; so there is a selection in favor of individuals with this trait HNHN → no sickle cell anemia D. Frequency-dependent selection - Perissodus microlepis - Stabilizing selection continued = highly specialized fish; predator that is a scale eater; moving up on a target fish, can attack on either left/right side of prey Dextral = head curved to the right, thus attacks the left side of prey Sinistral = head curved to the left, thus attacks the right side of prey if dextral were more common → fish would be more weary of attacks from the left side by the dextrals, which would give an advantage to the ones attacking on the right side (sinistrals); thus, the less common (sinistrals) would be favored There is an advantage at being the lower frequency, but there is an oscillation of frequency around the 50% line (page 18 PP); allele for sinistral is dominant so 50/50 oscillation is reached when the dominant allele is at 0.3 frequency and the other is at 0.7 → results in phenotypes of roughly 50%; studies show actual oscillation is 51-49%; frequency is stabilized at this point ^RARE GENOTYPE WILL ALWAYS BE FAVOURED Selection for one end of a range → directional selection Selection for the mean/average/middle and against the extreme ends → stabilizing selection Selection to achieve/maintain 50/50 ratio → frequency-dependent selection Selection in favor of extremes but against middle → disruptive selection

Monophyletic taxa

should have atleast on synapomorphy that they all share with nobody else -Hair is one syapomorphy of the monophyletic taxa of mammals All descendants within a node Paraphyletic/polyphyletic: when groups don't meet monophyletic criteria

Degenerate code

silent (no difference in phenotype/amino acid; synonymous; third one doesn't have much difference/effect) vs. replacement (there is a difference is phenotype/amino acid; non synonymous) point mutations third base is least likely to cause a change in DNA sequence

homology

similarities that result because of common ancestry even if natural selection has shaped them differently. - starts from similar characteristics and tends to cause them to diverge away from each other - they all develop from the same set of embryonic cells

analogy

similarities that result from a common origin but don't share the relationship - fins of shark and killer whales = NOT HOMOLOGY BUT homoplasy/_____/cconvergent evolution; live similar life histories so natural selection shapes them to similar characteristics

Frame shift

single base insertion or deletion - Insertion is adding and deletion is removing - Everything after insertion/deletion will be read differently - Not silent; effect varies, but generally more significant than a substitution - Produce new alleles (variant forms of genes); variance in alleles increases genetic variability and leads to different phenotypes but doesn't produce new genes - Point mutations don't produce new genes -Ex: Sea snakes: venomous; Dubois' Sea Snake is fish eater and Marbled Sea Snake eats fish eggs (don't need venom, they have atrophied fangs; non toxic venom, deletion caused frame shift in one of the venom protein genes)

point mutations

single base substitution (substituted, inserted, or removed genes, therefore point mutations can add bases, change bases, or delete bases) can change the amino acid that will be produced - Form new alleles of an existing gene but normally don't make new type of gene - Can be random errors in DNA synthesis A. Causes 1. Random errors in DNA synthesis (mistakes are made) 2. Mutagens (cause mutations) and unrepaired errors (repair mechanisms fail to correct error - Mutations are random in nature; they don't occur because they're needed DNA (transcription) → mRNA → (translation) Protein A-T G-C A-U

clad

single branch

variation and mutation categories of variation: A. genetic

situations btw genotype and phenotype are not always clear-cut

2nd postulate

some variation is heritable (can be inherited, genetic based); ex. Lung capacity and muscle; only heritable characteristics can be acted on through natural selection to lead to evolution B. Some variation heritable

common ancestry

species share common bones thus_________ ex) of _______ could be humans being more similar to monkeys. Dawsin said ________ showed a pattern - early embryology: more similar but then will later diverge -Ex) humans lose their tails, but dogs still have them

anagenesis

straight line without branching; between 1 and 6, there is descent with modification but no new species or taxa (genesis = origin of)

convergence

traits become similar even though no commonancestor

Autoapomorphy

unique derived characters (type of apomorphy unique to a branch); at the end; not good for showing relationships because it only shows one

importance of mutations

variation is critical to natural selection; if there are no variations, can't have any way to select one over another and have it passed on; those variations have to be hereditary and it is mutations that produce the variation; source of genetic variation is mutations →provide raw material for evolution

Synapomorphy vs Plesiomorphy

vertebral column in respect to turtles and leopards is a plesiomorphy because it does not distinguish the two synapomorphies of all vertebrates

DNA Methods

we use computers which can give more weight to things that are rare and put limitations on the computer

populations

what evolves?

Darwinism

what is evolution and natural selection? he is from middle to upper class family; had enough family money so that he didnt have to work, he could just perform research; started studying bio in 1820s and made his voyages in 1830's - wrote two books - he did not come up with the idea of evolution but his books brough the idea to the world public and provided much evidence for it.

null model of HW

what things would have to be true for nothing to change overtime? Leads to HWE I. Imbalance and eq'm II. Properties - Adults produce gametes; gametes represent gene pool; gametes that successfully fertilize will produce the next generation; different points of this process can alter the allele frequency what one-generation to the next A. Allele frequencies predict genotype frequencies B. Equilibrium - no change in allele frequencies C. Equilibrium in one generation D. Assumptions (1-4 are true = no change in allele frequencies)

cladogram

when the tree is formed by cladistics

basal group

when things are the same btw in/out group

chronological sequencing (geologic time scale)

you can date fossils in terms of sediment (deeper=older)

absolute dating

▪ What is its actual age rather than comparison ▪ Radiometric dating - uses unstable isotopes of naturally occurring elements - these isotopes decay, meaning that they change into either different elements or different isotopes of the same element - each isotope decays at a particular and constant rate, measured in a unit called a half-life - one half-life is the amount of time it takes for 50% of the parent isotope present to decay into its daughter isotope - the number of decay events observed in a rock sample are not affected by temperature, moisture, or any other environmental factor - radioactive isotopes function as natural clocks ▪ Ratio of isotopes - isotopes change overtime - figure out the half life of the isotope ▪ If want to look at recent mammals - carbon dating ▪ Potassium -argon and uranium - lead systems are the isotopes used to determine the age of earth ▪ Get much more precise over time ▪ Cannot use radio isotopes on planet because none of the rocks are old enough - no 4 billion year old rocks - moon, meteorites