BILD 3

Animalia

Obtain food by eating and digesting other organisms

plantae

Produce own sugars and other food molecules by photosynthesis

protists

Single-celled organisms

hatch mark

A character transition A place on an evolutionary lineage where a trait (character) changed

monophyletic

ALL descendants came from one common ancestor

tetrapod

Animal with 4 feet Amphibians, reptiles, mammals, birds Transition: fish to tetrapod (amphibian)

modes of selection

Directional Stabilizing Disruptive

random process

Ex: mutation, genetic drift, etc. Most have no effect at all

assortative mating

Like mates with like alleles Tend to see homozygotes if this occurs

disassortative mating

Like mates with unlike alleles produces heterozygotes can be considered a good thing

rooted

a branch point within the tree represents the most recent common ancestor of all taxa in the tree; unrooted= do not indicate root or location of the last common ancestor- shows the relatedness of organisms without indicating ancestry

systematics

a discipline focused on classifying organisms and determining their evolutionary relationships

sexual selection

a process in which individuals with certain inherited characteristics are more likely than other individuals of the same sex to obtain mates can result in sexual dimorphism and intrasexual selection

3 domains of life

bacteria, archaea, eukaryote

sister taxa

groups of organisms that share an immediate common ancestor that is not shared by any other group • They are each others' closest relative taxon (singular) taxa (plural) [named group]

ecology

how they interact with each other and their environments

descent with modification

term often used instead of evolution organisms share many characteristics--> unity of life from an ancestor of the past •Gradually accumulate diverse modifications as they live in various habitats leads to rich diversity of life that we see today

relative fitness

the contribution an individual makes to the gene pool of the next generation relative to the contributions of other individuals How likely an individual is to survive and/or reproduce compared to other individuals in its population

phylogeny

the evolutionary history of a species or group of species taxa grouped by RELATEDNESS historical classification: taxa grouped by SIMILARITY

genus

to which the species belongs

evolution

where they came from and how they change concept that organisms living on earth today are modified descendants of common ancestors descent with modification; a change in the genetic composition of a population from generation to generation Change in heritable traits (gene pool) over time

fungi

Absorb nutrients in dissolved form from their surroundings

deductive reasoning

Involves logic that flows from general to specific Uses "if... then" logic

evolution

**Evolution is a pattern and a process Pattern: Descent with modification and divergence Process (i.e. mechanism): Random process Natural selection (not random at all) Process: Adaptation to a change in environment Process: Change in genetic makeup over time Process: Individuals in a population with traits that help them survive/reproduce pass on their traits to future generations Pattern: New species arising Positive feedback: fit traits become more and more common Together, these evolutionary processes produce the pattern of descent with modification

local adaptation

- Birds come from South America to island A--> there are big seeds--> natural selection for big beaks because there are big seeds - Birds from island A move to island B--> small seeds there--> natural selection for small beaks - Birds from island B to island C--> lots of insects--> NS for long pointy beaks - As a result, 1 species splits into 3

character displacement

- Character: trait—Displacement: movement Birds from both island A and B go to island D--> island D has both big and small seeds--> island A finches with small beaks graph shifts a little to the left in order to level out--> would look like an [ln] graph, however, [fatter/rounder graphs that are more separated than your average bell graph] because of hyper competitiveness (gradient between the 2 is reduced bc they're outnumbered) Conclusion: more difference between A and B beaked species than before [fatter/rounder graphs that are more separated than your average bell graph]

evidence of evolution

- Fossil record - A. Consistent pattern of descent w modification - B. Transitional forms - C. Extinction - D. succession - Vestigial structures - Homology - A. Structural - B. Developmental - C. Molecular - Direct observation of changes (microevolution)

Steps for calculating whether a population is in HWE for a particular gene

1. Calculate the allele frequencies 2. Predict the EXPECTED genotype frequencies under HWE 3. Calculate EXPECTED genotype counts 4. Do a statistical test to decide if OBSERVED and EXPECTED genotype counts are significantly different If observed and expected are similar: it's in equilibrium; not evolving If different, population not in equilibrium; evolving

Darwin

1809-1882 Loved natural history Bombardier beetle: squirted acid down Darwin's throat His father wanted him to be a doctor, but he dropped out of medical school 1831: Darwin invited to be a volunteer naturalist aboard the HMS Beagle, which was sent to map wanters around South America at 22 years old - He took along Lyell's Principles of Geology

vestigial structure

A functionless or rudimentary structure in one species that has an important function in other, related species and was functional in their common ancestor Vestigial eyes in cave dwelling vertebrates a) Mexican tetra (live out in world; look like normal fish) b) Blind cave tetra (live in caves whole lives) - Common ancestor had functional eyes and pigment (to protect from radiation) - Cave tetra somewhere along timeline: lost pigment, scales over eyes, smaller eyes (aka vestigial eyes) bc no pigment, wouldn't be able to see anything if brought into real life - Another example: blind cave salamander with vestigial eye Flightless birds that still have vestigial wings: dodo, cassowary, great auk (extinct), flightless cormorant, kiwi - Not a coincidence that they're extinct: when birds move to an island and have no predators, they don't have to fly anymore when faced with predators, they all die (bc have lost their only defense function) Penguin wings are not vestigial: they're not flying, but they are used for a different function (to swim)

clade

A group of taxa and their MOST RECENT common ancestors An ancestor (node) and everything descended from it

maximum parsimony

A principle that states that when considering multiple explanations for an observation, one should first investigate the simplest explanation that is consistent with the facts. ex: Occam's razor

maximum likelihood

A principle that states that when considering multiple phylogenetic hypotheses, one should take into account the one that reflects the most likely sequence of evolutionary events, given certain rules about how DNA changes over time.

archaeopteryx

A transitional form between dinosaurs and birds from the late Jurassic (a type of bird) Toothed beak Winged claw Airfoil wing with contour feathers Long tail with many vertebrae Why did archaeopteryx have feathers? Modern birds use feathers for thermoregulation, nesting and keeping eggs warm, and color (attracting mate, camouflage) Ex: basking anhinga, male painted bunting, American bittern

Phenotype

An organism's physical appearance, or visible traits. Characteristics of an organism as a result of genes and the environment Can be determined by genes (snow geese coloration), the environment (beaks of male house finches based on available food), or both (human height- genes and nutrition)

fossil

Any trace record of an organism that lived in the past Fossils are found in sedimentary rock formation Plant and animal remains in sediment can become fossilized It's really rare that things actually get buried in sediment and thus fossilized Principle of stratigraphy: older things at bottom of rock and more recent ones near the top

wings

Bats: have 4 bones in wing and a tiny thumb Birds: have 1 bone in wing (essentially 1 big thumb) Shown as 2 different solutions to getting off the ground So, wings show convergent evolution

How were natural selection arguments countered?

Better understanding that earth is really old: Discovery of radioactivity and radiometric dating Current estimates: earth is 4.6 billion years old Better understanding of genetics: Modern synthesis: bringing Darwinian evolution and genetics together in 1930s Result: population genetics (coming soon)

trait

Characteristic; something you can measure about an organism

natural selection without evolution

Chimps learn to eat termites from others, so have more chance of survival The next generation doesn't learn this if there's no genetic component with a certain trait, it affects natural selection but not evolution

gene pool

Contribution of individuals' genes, but lose track of who's is who's Has frequency of certain genes Ex: 0.6 green alleles in gene pool from beetles; 0.4 brown Frequencies are 60% and 40% (used to be 80% green; 20% brown) Reasons the brown allele could have increased in frequency: Mutation Drought natural selection for brown allele Earthquake with natural disaster kills more green beetles by change Gene flow- beetles moving in/out of this population Sexual selection- brown is sexy

extinction

Controversy whether extinction was real The controversy ended with the discovery of the Irish elk Largest deer that ever lived. Largest antlers of any animal 1812: Cuvier studied the Irish elk and found it was different from any extant (still existing) animal He also described mastodons and other fossil vertebrates. Conclusion: extinction had happened Helped convince Darwin through suggestion of principle of succession

habitat specialists

Convergent evolution through competition (different species of lizards occupy different parts of the tree, specializing in canopy, trunk, and ground) One species specializes in canopy on Island A and another species in Island B, but through convergent evolution and independently, specialize in these habitats

Darwin's Origin of Species

Darwin says that all organisms evolved from a common ancestor. This was descent with modification (and divergence) The mechanism was natural selection Inspiration: adaptive radiations and biogeography

How were Darwin's ideas received?

Descent with modification from a common ancestor: widely accepted soon after publication Natural selection: universally rejected for 50-60 years

descent with modification and divergence

Descent with modification: throughout time, populations give rise to modified traits Divergence: splitting off on the tree As you look at older and older fossils, you see that they tend to be... Less and less similar to modern species More and more similar to one another [bc of common ancestor] More and more similar to the common ancestor of the group

variation

Do all individuals have an equal chance at surviving and reproducing? What traits of rabbits would affect their chances of surviving the obstacles we listed? Speed Able bodied Disease resistance Color of their coat/ability to camouflage Diet: bacteria in gut Ability to reproduce: reproductive biology Size Metabolism efficiency at different temperatures Do you think these traits VARY in a real rabbit population?

conventional wisdom at the time of Darwin

Each species created individually by God via "special creation" Most scholars accepted that the earth was older than 6000 years, but it was unclear how old (a few million years?) Paleontologists were finding fossils and documenting extinctions and changes over time Hints at the pattern (change over time), but not the process

testing for evolution by natural selection

Evolution by natural selection happens when: there is VARIATION in a HERITABLE characteristic that affects SURVIVAL AND/OR REPRODUCTION This is experimentally testable. Examples we've learned about where all 3 conditions were verified: Rock pocket mice (coat color) Galapagos ground finch (beak size) Guppies (bright coloration)

direct observation of changes (microevolution)

Evolution of pesticide resistance Field application of chemicals designed to kill all individuals creates strong selection for resistant genotypes Overuse of insecticides has caused many cases of evolved resistance in insects Shown in 1950-1980

limits on population growth

Factors affecting survival: disease, predators, humans (hunting/eating), food, shelter, natural disasters, emigration Factors affecting reproduction: insufficient habitat, pollutants What will happen to rabbit population in the long term? It will cycle up and down It will level off Possibly shrink to zero rabbits In real populations, more offspring are born than can survive and reproduce Elephants: start with 2 elephants, over 750 years, there will be 19 million elephants Struggle for existence

Darwin's finches

Galapagos finches Multiple species of same genus, all were different Led to ideas on adaptive radiation Large ground finch: Geospiza magnirostris Medium ground finch: Geospiza fortis Olive warbler finch: Certhidea olivacea

basic definitions

Gene: Functional unit of heredity Allele: Alternative form of a gene (D1 or D2, B or b, etc.) Diploid: Having 2 copies of each gene Genotype: The alleles an individual has for a gene (e.g., Bb) Population: Group of interbreeding individuals Allele frequency: Proportion of all the copies of a given gene that are a particular allele Frequency of allele A = p Frequency of allele a = q

Biogeography

Geographic distribution of species. Use evolution and continental drift to predict where fossils of diff organisms might be found

why is it worthwhile to test medicines on rats?

Have very similar parts and biochemistry and traits as humans because of homology (our common ancestor had all of these) Homology is why there's such a thing as a lab rat It's why the National Institutes of Health funds research on fruit flies, mice, frogs, yeast, and bacteria Homologous anatomy (mice, frogs, rats) Genes Biochemistry Learning about these species teaches us about human health

Neil Shubin

Him and his team went digging in exposed rocks of the right age (375 myo) Unfortunately, exposed rocks are usually in tough places (Canadian Arctic) They found tiktaalik (flattened head with eyes on top of head) Have wrist bones like fish but not fingers like tetrapods/humans Has these transitional features (some features of tetrapods; some features of fish) "fishapod" Aka tiktaalik is considered a RELATIVE of the ancestor of modern tetrapods

are these ecological communities stable over time?

Hispaniola = island of Haiti and D.R. Yes! They found 20 m.y.o. fossils of 3 living habitat specialist types (of anole lizards)

dispersal

How could a plant or animal colonize a new island? Darwin's conclusion: plants and animals could disperse on their own This allowed for plants and animals to disperse across oceans and colonize new volcanic islands Vegetation wraps floating down river—some have floating animals in them Happen from natural disasters (aka storms) One by one, plants take hold on island

struggle for existence

In every species, in every generation, MANY individuals die before they reproduce Ex: Elephants: start with 2 elephants, over 750 years, there will be 19 million elephants [expected to be more]

artificial selection

In food crops: Wild mustard evolves into cabbage (terminal bud), cauliflower (flower clusters), broccoli (flowers and stems), kohlrabi (stem), kale (leaves), and brussels sprouts (lateral buds) Also shows descent with modification

population growth

In rabbit paradise, over time, you would see exponential growth

convergent evolution of habitat specialists through competition

Island A: has canopy, trunk, and ground specialists Island B: has canopy, trunk, and ground specialists Both happened independently and both Islands have their own ecological community

principle of succession

Living organisms look similar to the fossils in their region because they are descended from those ancestors with modification Australia and Africa have been separated continents for 120 million years. Which do you predict would be most similar to 50myo fossils of Australian mammals? A) Australian living mammals B) African fossil mammals C) African living mammals Darwin found evidence suggesting principle of succession - Discovered the bones of extinct giant mammals in the cliffs - Recognized similarity to living species - Found it in living tree sloth vs giant ground sloth fossil and in giant armadillo fossil vs living armadillo

2 processes leading to divergence/new species/adaptive radiation

Local adaptation to different environments Competition leading to character displacement Results: an adaptive radiation

macroevolution

Major trait changes and new species Microevolution + millions of years = macroevolution i.e. same things are happening, just over a longer time

measuring microevolution

Microevolution: change in allele frequencies over time How can we tell when that is happening at a particular gene? Calculate what the expected genetic makeup of the population would be if it were NOT evolving at that gene (null model), and compare that to the observed (real) population If observed genotype counts = expected genotype counts: no measurable evolution and mating is random If observed is diff from expected: population may be evolving—differences can give us some clues about how If a pop is not mesasurably evolving and is mating randomly, gene pool is in HWE. HWE is the null model here.

human goose bumps

Muscles attached to hair follicles contract, makes hair "stand on end" When do you get goosebumps? Animals do that when they're scared or cold scared to expand skin to scare predators; cold to make fur fluffier for thermoregulation They are useless to us now but still try to do their job: a VESTIGIAL STRUCTURE in humans Other vestigial structures in human: tailbone, appendix, wisdom teeth - Appendix is only mostly vestigial

hypothesis that could explain our data

Mutation: NOT observable (too slow a process via HWE test) COULD BE natural selection Assortative mating-- tends to produce excess HOMOZYGOTES Gene flow: Immigration of TT and tt weasels Emigration of Tt weasels

evolution by natural selection

Natural selection: occurs when a particular version of a trait makes the individuals who have it more likely to survive or reproduce Evolution: change in a population's heritable traits or gene pool over time evolution by natural selection happens whenever there is variation in a heritable trait that affects survival and/or reproduction

A population is in HWE at a particular gene if all these conditions are met

No natural selection No new mutation No genetic drift (so a very large population) No gene flow/migration Random mating (no interbreeding, etc.) If any of these conditions are NOT met, that can change genotype frequencies in a population

Darwin's theory of evolution

Pattern: descent with modification and divergence Process (mechanism) - Random processes (mutation, genetic drift, etc.) - Natural selection (not random at all)

paraphyletic

Pertaining to a group of taxa that consists of a common ancestor and some, but not all, of its descendants. ex: everyone is at home except for one of the kids ex: reptiles

adaptive radiation

The diversification of species origination from a common ancestor to fill a wide variety of ecological niches Picture of bird branching out to other types of beaks Overall shape (radiation = outwards; adaptive = to environment)

Heritability

The proportion of variation among individuals that we can attribute to genes. The heritability of a trait may vary, depending on the range of populations and environments studied. Are some of these traits heritable (genetic)? Hair color Eye color Not heritable: A missing foot Body mass Just because things run in the family doesn't mean it's genetic Ex: language (you're not born with speaking Spanish in your genes, it's taught to you) If a trait is at least partly heritable, then offspring tend to be similar to their parents for that trait The next generation tends to resemble the survivors of this generation

horizontal gene transfer

The transfer of genes from one genome to another through mechanisms such as transposable elements, plasmid exchange, viral activity, and perhaps fusions of different organisms.

developmental homology

Trait present in embryo Inherited similarities during development, despite differences in adults Vertebrate embryos: all have pharyngeal pouches (similar to gill slits of fishes) All have tails—tail remnant in both chicken and human embryos Homologies of what embryo looks like

histogram

Type of graph Different from bar graph because histograms have numerical values while bar graphs don't (i.e. favorite color)

allele

Version of a gene

anole lizard

Widespread on Caribbean islands including Hispaniola Habitat specialists demonstrate convergent evolution Convergent evolution through competition (different species of lizards occupy different parts of the tree, specializing in canopy, trunk, and ground) One species specializes in canopy on Island A and another species in Island B, but through convergent evolution and independently, specialize in these habitats

founder effect

a few individuals become isolated from a larger population, this small group establishes a new population with different gene pool from the source population o Ex: a few members are blown by a storm to a new island • Accounts for high frequency of certain inherited disorders among isolated human populations o Ex: 15 British colonists found a settlement, one has a recessive gene for blindness 4 end up with it a lot higher frequency than in higher population

fixation

all members of the population have the same allele of a particular gene ex: with all black or all white coats for mice

genetic drift

causes allele frequencies to fluctuate unpredictably from one generation to the next, especially in small populations Certain circumstances can result in genetic drift having a significant impact on a population: founder effect bottleneck effect • Genetic drift is essential in small populations o An allele can be very over or under-represented • Genetic drift can cause allele frequencies to change at random • Genetic drift can lead to a loss of genetic variation within populations • Genetic drift can cause harmful alleles to become fixed happens in ALL populations, not just small ones, but most visible/strongest in small populations reduces genetic variation over time as alleles are fixed or lost changes allele frequencies at random can fix harmful alleles

cladistics

common ancestry is the primary criterion used to classify organisms

Hardy-Weinberg equilibrium

condition that occurs when the frequency of alleles in a particular gene pool remain constant over time conditions: • No mutations • Random mating • No natural selection • Extremely large population size (genetic drift happens in small pops) • No gene flow

bilaterally symmetrical

describing an animal whose morphology on one side of the midline is a mirror image of the morphology on the other side (an animal who has a mirror image basically)

sexual dimorphism

difference in secondary sexual characteristics between males and females of the same species, including differences in size, color, ornamentation, and behavior

lineage

direct descent from an ancestor; derivation path through the tree

eukarya

distinguished by modes of nutrition: plantae fungi animalia protists

scala naturae

each form of life had its allotted rung on this ladder/scale of increasing complexity (linear hierarchy) Ideas consistent with Old Testament Binomial names contradicts this

Cuvier

father of paleontology oThought each boundary between strata represented a sudden catastrophic event (a flood), destroying many of the species brought up idea of extinction

frequency-dependent selection

fitness of phenotype depends on how common it is in population

processes that violate the assumptions of Hardy-Weinberg Equilibrium

genetic drift: change in the genetic composition of a population caused by random sampling drift is a random process that can change the allele frequencies in any way, but effects are only noticeable in one generation (departing from HWE)...PPT 4.28 ALSO... mutation natural selection non-random mating gene flow

taxonomy

how organisms are named and classified

phylogenetic tree

how the evolutionary history of a group of organisms can be represented in a branching diagram branching diagram shows relationships among taxa shows patterns of ancestry uses all possible types of data must be inferred: reconstructing the past we didn't see represents a hypothesis about how evolution happened

stabilizing selection

o Acts against both extremes, favors intermediate phenotypes o Reduces variation, maintains status quo for phenotypes o Ex: baby weight when born; too big or small leads to higher rates of mortality An intermediate phenotype is the most fit (somewhere in the middle) Middle of the graph shoots upwards (narrower and taller) Selection against wider values of phenotype, selection for middle values of phenotype Effects: The population mean stays the same The population variation (avg distance from the mean) decreases Ex: human birth weight

directional selection

o Occurs when conditions favor individuals exhibiting one extreme of a phenotypic range shifting a population's frequency curve for the phenotypic character in one direction or the other o Common when an environment changes or when members of a population migrate to a new habitat o Ex: large seeds > small seeds increase beak depth An extreme phenotype is the most fit Ex: altitude tolerance in Tibetan women Women with low oxygen saturation of hemoglobin have fewer surviving offspring Women with high oxygen saturation of hemoglobin have more surviving offspring Effects: The population mean changes

bacteria

o Prokaryotic o Cell-like

archaea

o Prokaryotic o Live in extreme environments like salty lakes and hot springs

disruptive selection

o When conditions favor individuals at both extremes over individuals with intermediate phenotypes o Ex: birds with medium bills are inefficient at cracking both large and small seeds have lower fitness Two extreme phenotypes are more fit that intermediate phenotypes Effects: The population mean STAYS THE SAME The variation increases (it's overall more spread out) ex: black-bellied seed cracker eats seeds from plants with either hard or soft seeds

Hardy-Weinberg equation

p^2 + 2pq + q^2 = 1 Look at what the genetic makeup of a population would be if it were not evolving at that locus compare with data we actually observed for the population

polyphyletic

pertaining to a group of taxa derived from two or more different ancestors ex: house and family but neighbor kid has come to visit ex: marine mammals

basal taxon

plural: taxa a lineage that diverges from all other members of its group early in the history of the group A named level in the hierarchy A named genus, species, etc. at the end of points on a phylogeny tree

fossils

remain in strata layers of rock

vestigial structures

remnants/leftovers of features that served a function in the organism's ancestors

branch point (node)

represents the common ancestor of the 2 evolutionary lineages diverging from it on phylogenetic tree Represents the common ancestor of 2 lineages

intrasexual selection (aka mate choice)

selection within the same sex, individuals of one sex compete directly for mates of the opposite sex • Occurs among males: many males attack smaller, weaker males • Individuals are choosy in selecting mates from the other sex

analogous structures

share similar function but not common ancestry

homology

similarity resulting from common ancestry A trait that two species share because they both inherited it from their common ancestor Wings are not a homology for birds and bats Backbones are a homology for birds and bats Tetrapod forelimbs have the same basic structure despite different function Why? Because all of these are modifications of a shared ancestral form

homologous structures

skeletons of arms, forelegs, flippers, and wings of diff mammals that represent variations on a structural theme that was present in their common ancestor share common ancestry, but not necessarily similar function

Hutton and Lyell

suggested that profound change could take place through cumulative effect of slow but continuous processes—these influenced Darwin's thinking

analogy

the result of convergent evolution Are bird and insect wings homologous? No—they're extremely different structures (insect wings don't have wings) Sabertooth cat is a placental mammal—saber-toothed metatherian and this have a common ancestor with normal canine teeth

gene flow

the transfer of alleles into or out of a population due to the movement of fertile individuals or their gametes can bring in genotypes from a neighboring population These new frequencies alter our original population Reduces the genetic differences BETWEEN populations • Can even result in 2 populations combining into 1 Gene flow can: alter allele frequencies in populations reduce genetic differences among populations counteract the loss of genetic variation caused by drift can oppose natural selection and adaptation ex: bent grass growing on and near an old copper mine

biodiversity

the variety of life in the world or in a particular habitat or ecosystem. what they are

parenthetical citation

to see if 3 trees are equally equivalent, use parenthetical citation to see if all trees are the same ex: ((((E,D), C), B), A) ((((E,D), C), B), A) ex: (((A, B), (C, D)), E)

fitness plot

trait vs. fitness

amniote

vertebrate whose embryo or fetus is enclosed by a thin, tough membranous sac

neutral variation

when a mutation is neither advantageous nor disadvantageous

bottleneck effect

• A sudden change in the environment (fire or flood), drastically reduces size of population bottleneck effect • By chance alone, certain alleles are overrepresented among survivors while others are underrepresented, some are absent altogether • Has substantial effects on gene pool until population becomes large enough again that it has less impact

heterozygote advantage

• Individuals who are heterozygous at a particular locus have greater fitness than do both kinds of homozygotes • Defined in terms of genotype, not phenotype • Ex: if the phenotype of a heterozygote is intermediate to the phenotypes of both homozygotes, heterozygote advantage is the form of stabilizing selection

binomial

•First part of name is genus •Second part is unique to species within genus •Goes against/contradicts scala naturae Binomial: the two-part format of the scientific name • Genus: to which the species belongs • Specific epithet: unique for each species within the genus

J.B.S. Haldane

Testing the theory of evolution Asked: what evidence would destroy your confidence in the theory of evolution? Answer: a fossil rabbit in the Precambrian Theres nothing in the Precambrian for a rabbit to be descended FROM. So, a Precambrian rabbit fossil would break the pattern that we see Precambrian time is way long ago even before the dinosaurs Tertiary period: rabbits Cretaceous: dinosaurs Precambrian: mostly squishy things

voyage of HMS Beagle

Punta Alta, Argentina - Discovered the bones of extinct giant mammals Chile: Andes Mountains - Found fossil marine shells in sedimentary rock at 12,000 ft - Witnessed volcanic eruption and a massive earthquake that raised portions of the coastal shelf by 8 ft - Lyell: the forces observable today can create what we see around us, given enough time. Therefore, the earth must be very old (a series of gradual changes) Galapagos Islands - An important stop, although Darwin didn't realize it at the time. It took him awhile to put it together - Darwin realized that for some groups of organisms, different islands supported distinct species and subspecies - Ex: Galapagos tortoises (domed shell, saddleback shell, intermediate shell; all have different traits and correspondence with environment on the island aka food to eat and ability to walk through the ground)

Why was natural selection rejected?

Religious belief of divine purpose Scholars thought Earth wasn't old enough for natural selection to create the diversity we see today No understanding of inheritance; it wasn't clear how traits were passed down to descendants

after Darwin's voyage

Returned to England in 1836 Wrote Origin of Species in 1859 What did he do for 23 years? Collected reams of evidence to support his ideas that would eventually give rise to the Origin of Species Bred pigeons (1855) Different kinds of pigeons could be created from a common ancestor Traits were SELECTED for. Pigeon breeders had been doing this for years This was ARTIFICIAL SELECTION (fantail pigeon, pouter pigeon, rock pigeon, carrier pigeon)

microevolution

Short time scales Change in the genetic composition of a population across several generations Ex: alleles in beetles changing (gene pool slide)

ancestor tree

Shows lines of species over time (small dots along line) and common ancestors between species (intersection between lines)

convergent evolution

Similar traits that arose independently Ex: Dragonfly and Macaw share wings, but evolved these wings separately (because their common ancestor didn't have wings—it appeared as a slug)

molecular homology

Similarities among organisms at the molecular level Genetic code: in nearly all organisms, the same codons (nucleotide triplets) specify the same amino acid If you have a mutation at molecular level, it's been weeded out over time Many genes are also homologous (e.g., huntingtin in humans and fruit flies)

natural selection

individuals whose inherited traits give them a higher probability of surviving and reproducing in a given environment tend to leave more offspring than do other individuals (overreproduce) This unequal ability of individuals to survive and reproduce will lead to the accumulation of favorable traits in the population over generations Happens whenever there is 1. variation in a trait 2. that affects survival and/or reproduction Natural selection: occurs when a particular version of a trait makes the individuals who have it more likely to survive or reproduce Natural selection can't happen to an individual over time, but it can make the average rabbit population faster over time [natural selection changes populations, not individuals] Will the next generation of rabbits be faster as a result of natural selection in this generation? Not enough information to tell: have to see if genes are heritable (?)

nested hierarchy

like a phylogeny tree but nested into circles based on species, genus, family, order, class, phylum, and kingdom how to do historical classification realize that animals have similar classification because they're related

balancing selection

maintains polymorphism in a population -heterozygote advantage -(negative) frequency dependent selection