Biology Exam 3

New Bodies

Evolution in body types Simpler body forms have fewer Hox genes Vertebrates have several copies of the 13 gene Hox cluster - several duplication events

what are two sources of genetic variation

Mutation Recombination

Mutation

nonadaptive - a direct change in the DNA sequence of the germ cells mutations are rare per locus at 1/106 Random with regard to affect on phenotype - ultimate source for genetic variation

Gene Flow or migration

nonadaptive - genetic exchange of fertile individuals between populations - new individuals moving into and out of the population alter the frequency of alleles in a population

Anagenesis

phyletic evolution - transformation of one species into another

Introgression

the spread of genes from one species to another via hybridization particularly in plants where new lines can reproduce asexually

Non-synonymous substitution

changes AA sequence Most are deleterious

geneticist

changes in allele frequency from one generation to the next - measures genotypic variation

Heterochrony

changes in the rates of developmental timing, leading to changes in size and shape

ecologist

changes in traits from one generation to the next - measures phenotypic variation

Phylogenetic reconstruction based on shared derived characters is called ____________.

cladistics

Mutation

ultimate source of genetic variation only mutations in the germ line can be inherited mutations are random with respect to fitness Point mutations and chromosomal rearrangements Small source of variation

Aristotle

"Great Chain of Being" Species are fixed types Some are "higher" - more complex

Paleozoic Era

- 544 - 245 mya - origin of most plant and animal phyla - Cambrian explosion - colonization of land by plants and insects - radiation of bony fishes, first amphibians, gymnosperms - first amphibian and reptiles radiations - first mammal-like reptiles - modern insect orders - Mass extinctions of aquatic and terrestrial organisms Volcanic activity Oceanic turnover - Pangaea coalesced

Absolute Dating

- Radiometeric dating - based on half-life - 14C, 238U, 32P - Amino acid transformation - rate of breakdown from L- to D- forms

Cladogenesis

- branching evolution - building of one or more species from an ancestral (parent) species

allopatric speciation

- geographic barriers isolate populations and function as barriers to gene flow

Relative Dating

- relative to other fossils in geologic strata - presence of certain fossils define certain strata

Parapatric Speciation Dispersal

-Parapatric- no specific extrinsic barrier, but population does not mate randomly Dispersal- the movement of individuals into new novel habitats

Limitations of Fossils

1) Animals had to die in the right place 2) The fossils had to avoid geologic damage 3) The fossil has to be exposed 4) The fossil has to be found 5) Most soft-bodied animals probably left no fossils

Genetic and Phenotypic Variation

1) Need variation for Natural Selection to act upon 2) Phenotypic variation is extensive genetically based phenotypic variation has a heritable basis environmentally induced variation The specific trait is not directly heritable but the ability to change phenotype may be 3) Types of heritable traits A. Discrete traits - categorical in nature e.g. dominant and recessive B. Quantitative or continuous traits - continuous variation in trait - follow a normal distribution can be the result of the interaction among many genes polygenic traits - epistasis - multiple loci acting on a single trait e.g. height, color patterns

Darwin's 5 observations

1) Over-production Many more individuals are born in each generation than will survive to reproduce Thomas Malthus - inspired Darwins intuition about animal populations 2) Variation - variation within populations - similarity between mainland and island species 3) Differential Reproductive Success individuals with certain traits have a better chance of surviving and reproducing than others with slightly different traits 4) Heritability Some of the traits resulting in differential survivorship and reproduction can be passed from one generation to the next 5) Time Changes have occurred over vast periods of time Measured in generations

Darwin's Logic of Natural Selection

1) populations potential to increase exponentially - exponential growth is not realized - resources are limited INFERENCE individual struggles results in not all surviving to reproduce 2) variation among individuals 3) differences can be passed from one generation to the next (heritable) INFERENCE Individuals with heritable traits that increase their survival and reproduction will leave more offspring INFERENCE The unequal ability of individuals to survive and reproduce will result in gradual change over generations

Points of Natural Selection

1) variation is among individuals 2) only populations evolve 3) only amplifies heritable traits 4) is NOT random 5) is context specific in space and time 6) is a gradual, slow process requiring many generations

Mesozoic

245 - 65 mya Triassic - 245 - 206 mya - first dinosaurs, birds, gymnosperms dominant Jurassic - 206 - 144 mya - Bony fish radiation dinosaurs, gymnosperms dominant First mammals, Cretaceous - 144 - 65 mya Laurasia and Gondwana Angiosperms appear mass extinction at the end Modern continents by the end

Precambrian Era

4500 mya - origin of earth 3800 mya - oldest fossils known - prokaryotes 2500 mya - O2 accumulates 1500 mya - oldest eukaryotes 700 mya - first animals

5) 4 separate populations are studied in a lab. A population of 5 humans, 100 humans, 100 EColi, and 5 EColi. EColi reproduces every twenty minutes, on average. On average, the humans in the lab are reproducing every twenty five years. Which group will experience genetic drift the fastest a) 5 Humans b) 100 Humans c) 5 Bacteria d) 100 Bacteria

5 bacteria

Cenozoic

65 mya to present Paleogene - - major radiations of angiosperms mammals, birds, and insects - modern mammal orders, apes Neogene - ape like ancestors of humans appear - modern ice ages - modern humans appear - mass extinction

Sexual Selection

A subset of natural selection in which a traits fitness is exclusively related to reproduction females selecting males with specific traits traits that provide males with an advantage in contests for access to females Creates exaggerated traits through a positive feedback loop with female choice for males with extreme traits - runaway selection

The Pattern Resulting from Evolution - Change through Time

Age of the Earth (4.5 billion years) Fossil record(transitional features-Intermediates between ancestors and descendants) Fossil Record(extinction) Vestigial Traits(reduced/incompletely developed traits that were present in common ancestor) Homology (similarity in form in common descent) Developmental Homology Genetic Homology Evidence from biogeography

common ancestry

All existing organisms are modified descendants of other organisms

8) The type of speciation described in question seven is: a) Allopatric Speciation b) Sympatric Speciation c) Instantaneous speciation

Allopatric speciation

Biological Factors

Competition Habitat destruction (humans) --- as many as 1/5 of all species may become extinct in next 30 years.

Continental Drift

Earth is composed of several crustal plates that have moved extensively throughout the history of the earth Resulted in geographic isolation of species - lungfish in Africa, South America, and Australia - isolated marsupials in Australia

Hardy-Weinberg Theorem

Frequencies of alleles and genotypes in a population's gene pool will remain constant over generations unless acted on by agents other than sexual recombination. The genotype frequencies can be predicted by a binomial expansion (p + q)2 = 1 A population in Hardy-Weinberg equilibrium will not experience a change in allele frequencies. Assumptions: NO EVOLUTION No microevolutionary processes - mechanisms that change allele frequencies in populations genetic drift, gene flow, selection, mutation Infinite population size Random Mating A population that is not in H-W equilibrium will reach equilibrium in one generation. Rare deleterious alleles can persist for long periods of time in heterozygotes

Phylogeny - the Pattern

Illustrates the concept of common ancestry - species that are different have a more distant common ancestor than those that are more similar

Jean-Baptiste de Lamarck

Organisms change over time! Revolutionary! Spontaneously originate at base of Scala Naturae and "evolve" upward toward something more complex Inheritance of acquired traits Wrong mechanism

Evolutionary Radiations

Rapid divergent evolution within a lineage in a relatively short time. Adaptive zones opened by novel characteristics or the elimination of competing groups - fur on mammals - flight in birds Often "adaptive" changes Relationships among taxa can be difficult to determine because of the rapid speciation rate

Phylogenetics

Reconstructing the evolutionary history of a lineage and showing ancestor-descendant relationships in a tree

Homeobox genes

Regulatory genes that control the rate of development Mutations in homeobox genes that change the regulation of development and result in novel structures Major mechanism for evolutionary change that may underlie speciation Are homologous and ancestral to all animals

Artificial Selection

Selection by humans for breeding of useful traits from the natural variation among different organisms

Darwin's and Wallace's Impact

Species were no longer considered static Replace typological thinking with Population thinking Scientific - proposed a testable mechanism for change over time Natural selection

Fitness

The confusion of "survival of the fittest" The measure of differential survival and reproduction Number of offspring, grand offspring Number of matings Survival rate Not a measure of strength or ability

Extinction

The end of a lineage - the last individual of a species dies Background Extinction normal extinction rate, relatively constant Mass extinctions periodic extinction events that coincide with major environmental changes 1)Late Ordovician 2)Late Devonian 3) End Paleozoic (Permian) 4) Cretaceous - Tertiary 5) Modern day

Secondary Species Contact

Two previously separated populations once again come into contact 1) interbreed freely - no speciation 2) reproductive barriers have evolved - speciation 3) hybrid zone - interbreeding occurs however the zone of introgression is narrow and the populations remain distinct

Plato

Typological Thinking Species do not change over time Variants are misleading and uninformative

Mammalian foregut fermenters

Use specialized lyozyme to digest cell walls in foregut Similar adaptation in biochemical structure among unrelated species Langurs and cows have virtually the same form convergence Duplicate genes allowed for new forms of lysozyme

Selection - the Process

Variation in a heritable trait that results in differential survivorship and reproduction (fitness differences) Then the trait that increases fitness will become more common within the population over-generations

Hox genes

Variation in number and type of Hox genes Copies of the genes most likely arose through gene duplication Some of the Hox genes have been lost

____________ refers to a system in which individuals select their mates according to phenotype. a. Assortative mating b. Random mating c. Differential mating d. Sexual selection e. All of these

a. Assortative mating

species

a group of living organisms consisting of similar individuals capable of exchanging genes or interbreeding

paraphyletic group

a group that does not contain all descendants of an ancestor

polyphyletic group

a group that has more than one ancestor

population

a localized group of individuals in the same species

3) If allele frequencies do not change: a) Hardy Weinberg Theorem has held true b) Hardy Weinberg has been violated c) Evolution has occurred d) Natural selection has not occurred

a) Hardy Weinberg Theorem has held true

4) In a population of giraffes, the tall giraffes tend to fall in love easier with each other because of their similar size. Which of the following is true? a) Hardy Weinberg has been violated b) Genetic drift will occur c) The population of giraffes will experience a bottleneck d) Assortative mating will occur

a) Hardy Weinberg has been violated d) Assortative mating will occur

6) A highway is built down the middle of a swamp, and a population of turtles is split into two. Over time they evolve into two completely separate species. Which of the following has occurred? a) Vicariance b) Cladogenesis c) Anagenesis d) Dispersal

a) Vicariance b) Cladogenesis

The diagram below depicts three phylogenetic trees. Which of the three shows the same sister group relationships among groups A, B, and C? a. 1 and 2 are equivalent. b. 2 and 3 are equivalent. c. 1 and 3 are equivalent. d. All 3 are equivalent. e. All 3 are different―no two are equivalent.

a. 1 and 2 are equivalent.

Why is the fossil record not a complete catalog of biological history? a. Not all organisms fossilize with equal probability. b. Fossilization destroys the structure of DNA. c. The process of fossilization often destroys anatomical features of the organisms being preserved. d. Fossils only preserve organisms for about 10 million years; older organisms are destroyed by geological processes. e. Only animals, not plants, are fossilized.

a. Not all organisms fossilize with equal probability.

Different species of fruit flies occupy each of the islands in the Hawaiian island chain, a group of volcanic islands that formed one after the other. One hypothesis for how the different fruit fly species formed is that, after each new island was formed, fruit flies from existing islands colonized it and subsequently diverged. If this hypothesis is correct, it would be an example of: a. allopatric speciation by dispersal. b. allopatric speciation by vicariance. c. peripatric speciation by vicariance. d. sympatric speciation by dispersal. e. sympatric speciation by vicariance.

a. allopatric speciation by dispersal.

You've likely heard of polar bears (Ursus maritimus) and grizzly bears (Ursus arctos horribilis). Have you heard of a grolar bear or a pizzly bear? These might be unfamiliar because they are the offspring of matings between polar bears and grizzlies. A handful of these animals have been born in zoos; three have been documented in nature. Due to their rarity, only a few grolars (grizzly dad and polar bear mom) or pizzlys (polar bear dad and grizzly mom) have been studied in detail. Their fur color, head shape and ear shape (see figures above) are striking intermediates between the phenotypes of their parents. It is thought that polar bears originated from a population of brown bears (Ursus arctos) that became geographically isolated during a glaciation event that occurred about 150,000 years ago (Lindqvist et al., 2010). Traditionally the territories of grizzly bears and polar bears did not overlap, as grizzlies ranged from Alaska to Mexico, whereas polar bears stayed on the annual sea ice over the Arctic continental shelf and within the Arctic archipelagos. Relatively recently (last 50 years or so) grizzlies and polar bears have begun to come in contact in the wild. The origin of polar bears was the result of: a. allopatric speciation. b. sympatric speciation. c. peripatric speciation.

a. allopatric speciation.

In contrast to positive and negative selection, ____________ acts to maintain two or more alleles in a population. a. balancing selection b. disruptive selection c. stabilizing selection d. directional selection

a. balancing selection

In general, sympatric speciation requires the action of ____________ selection acting against hybrids. a. disruptive b. stabilizing c. directional d. artificial e. ecological

a. disruptive

All alleles present in all individuals of a species are referred to as the -------- of that species a. gene pool b.allele frequency c. genotype frequency d.genotype e. phenotype

a. gene pool

Characters that are similar because of descent from a common ancestor are ____________; characters that are similar due to convergent evolution are ____________. a. homologous; analogous b. analogous; homologous

a. homologous; analogous

10. Instantaneous speciation: (select all correct choices) a. is, by definition, a type of sympatric speciation. b. is typically caused when hybridization between species produces fertile, viable offspring that are reproductively isolated from both parental species. c. often involves the multiplication of chromosome sets, or polyploidy. d. is relatively common in plants but not in animals. e. none of these

a. is, by definition, a type of sympatric speciation. b. is typically caused when hybridization between species produces fertile, viable offspring that are reproductively isolated from both parental species. c. often involves the multiplication of chromosome sets, or polyploidy. d. is relatively common in plants but not in animals.

A taxon that includes a single common ancestor and all its descendants is a ____________ group. a. monophyletic b. paraphyletic c. polyphyletic

a. monophyletic

Several species of fireflies are active on the same summer nights in the same fields. Males and females recognize one another by their distinctive flashing patterns. This is an example of what kind of reproductive isolation? a. pre-zygotic, behavioral isolation b. pre-zygotic, temporal separation c. pre-zygotic, ecological separation d. post-zygotic, lock and key e. post-zygotic, ecological separation

a. pre-zygotic, behavioral isolation

Genetic drift is the ____________ in allele frequencies from generation to generation and is especially important in ____________ populations. a. random change; small b. random change; large c. change due to selection; small d. change due to selection; large e. none of these

a. random change; small

The result of migration is to ____________ genetic differences among populations. a. reduce b. increase

a. reduce

The differential success of alleles is called ____________. a. selection b.genetic drift c. fixation d. migration e. evolution

a. selection

In a phylogenetic tree, a node or branching point represents: a. the common ancestor from which the descendent species diverged. b. the species in the fossil record from which the descendent species diverged. c. one of the descendent species in the phylogeny. d. the ancestral species from which all species in the phylogeny arose. e. A node could be any of these, depending on the nature of the phylogenetic tree.

a. the common ancestor from which the descendent species diverged.

Natural Selection

adaptive differential survivorship and reproduction among individuals within a population Natural selection acts on the phenotype - only changes in the genotype can result in evolutionary change Evolution by NS is constrained by the amount of genetic variation in the population

Cell Theory

all cells come from prexisting cells

Fixed

all of the alleles at a locus are the same within a population e.g In a population where all individuals have the genotype AA allele frequency = 1

Homeosis

alterations in the placement of different body parts spatial displacement - additional segments in segmented organisms

fossils that retain organic material

amber, freezing, mummification - potential to provide DNA

Node

ancestral group splits, new groups

Alleles

are different forms of the gene at the same loci = 2 copies at each locus

Two species of antelope ground squirrels are separated by the Grand Canyon. They are hypothesized to descend from a common ancestor, populations of which were separated as the canyon formed. If this hypothesis is correct, it would be an example of: a. allopatric speciation by dispersal. b. allopatric speciation by vicariance. c. peripatric speciation by vicariance. d. sympatric speciation by dispersal. d. sympatric speciation by vicariance.

b. allopatric speciation by vicariance.

To conduct a phylogenetic analysis, we need an outgroup to: a. decide which characters are analogous and which are homologous. b. determine which character states are ancestral and which are derived. c. determine which characteristics to include in our analysis. d. decide which molecular data to use. e. All of the answer options are correct.

b. determine which character states are ancestral and which are derived.

When the conditions of the Hardy-Weinberg equilibrium are met: (select all correct choices) a. evolution occurs. b. evolution does not occur c. gene frequencies in the population change over time. d. gene frequencies in the population do not change over time. e. none of these occur when conditions of the Hardy-Weinberg equilibrium are

b. evolution does not occur d. gene frequencies in the population do not change over time.

What is a trace fossil? a. a small fossil b. fossil evidence of organisms other than conventional fossils of hard body parts c. a fossil which is part of a series of fossils that trace the evolution of a group of species d. a fossil that allows scientists to trace the movement of the fossilized organism

b. fossil evidence of organisms other than conventional fossils of hard body parts

All else being equal, selection should more strongly favor reinforcement of reproductive isolation among related species: a. in allopatric populations over sympatric populations. b. in sympatric populations over allopatric populations. c. in peripatric populations over sympatric populations. d. in peripatric populations over allopatric populations. e. in allopatric populations over peripatric populations.

b. in sympatric populations over allopatric populations

2) The unit of evolutionary change is: a) Individual b) Population c) Species d) Genus e) Family

b. population

Two species of frog mate in the same pond. One breeds in early summer and one in late summer. This is an example of what kind of reproductive isolation? a. pre-zygotic, behavioral isolation b. pre-zygotic, temporal separation c. pre-zygotic, ecological separation d. post-zygotic, temporal separation e. post-zygotic, ecological separation

b. pre-zygotic, temporal separation

How does the fossil record corroborate phylogenetic history? a. Fossil record events are too old to be represented on phylogenetic trees, which reconstruct the more recent past. b. Events that occur early in the fossil record are represented by branching events nearer to the tips of a phylogenetic tree. c. Events that occur early in the fossil record are represented by branching events nearer to the root of a phylogenetic tree. d. The timing of evolutionary events in the fossil record is not consistent with the branching order of a phylogenetic tree. e. Events in the fossil record occur randomly throughout a phylogenetic tree, so the two are not related to one another.

c. Events that occur early in the fossil record are represented by branching events nearer to the root of a phylogenetic tree.

How do fossils provide evidence of evolutionary history? a. Fossils provide an accurate account of the number of species that exist at any particular time. b. Older fossils are an excellent source of DNA from which we can construct molecular phylogenies. c. Fossils provide a record of extinct species. d. Fossils provide complete information on extinct species.

c. Fossils provide a record of extinct species.

You've likely heard of polar bears (Ursus maritimus) and grizzly bears (Ursus arctos horribilis). Have you heard of a grolar bear or a pizzly bear? These might be unfamiliar because they are the offspring of matings between polar bears and grizzlies. A handful of these animals have been born in zoos; three have been documented in nature. Due to their rarity, only a few grolars (grizzly dad and polar bear mom) or pizzlys (polar bear dad and grizzly mom) have been studied in detail. Their fur color, head shape and ear shape (see figures above) are striking intermediates between the phenotypes of their parents. It is thought that polar bears originated from a population of brown bears (Ursus arctos) that became geographically isolated during a glaciation event that occurred about 150,000 years ago (Lindqvist et al., 2010). Traditionally the territories of grizzly bears and polar bears did not overlap, as grizzlies ranged from Alaska to Mexico, whereas polar bears stayed on the annual sea ice over the Arctic continental shelf and within the Arctic archipelagos. Relatively recently (last 50 years or so) grizzlies and polar bears have begun to come in contact in the wild. What information would assist you in determining whether polar bears and grizzlies are different species, based on the biological species concept? I. whether the F1 is fertile II. whether F1 offspring are viable III. the level of sequence (DNA) divergence between polar and grizzly bears IV. the geographic distribution of polar and grizzly bears a. I only b. II only c. I and II only d. I and III only e. III and IV only

c. I and II only

The largest mass extinction occurred at the end of the: a. Ordovician. b. Devonian. c. Permian. d. Triassic. e. Cretaceous.

c. Permian.

At the genetic level, evolution is: a. a change in fitness over time. b. a population change over time. c. a change in the frequency of an allele or genotype over time. d. an increase in fitness over time. e. natural selection.

c. a change in the frequency of an allele or genotype over time.

What is the first event in the fossilization process? a. hardening of sediments in to rock b. erosion of soils around the organism c. burial of the organism by sediments d. conversion of organic tissue to minerals (rock)

c. burial of the organism by sediments

The extinction of the ____________ during the end-Cretaceous mass extinction allowed mammals to diversify through the process of ____________. a. ammonites; peripatric speciation b. dinosaurs; peripatric speciation c. dinosaurs; adaptive radiation d. ammonites; adaptive radiation e. cephalopods; adaptive radiation

c. dinosaurs; adaptive radiation

A taxon that does not include the last common ancestor of all its members is a ____________ group. a. monophyletic b. paraphyletic c. polyphyletic

c. polyphyletic

Biochemical systems within the stigma of a flowering plant prevent the pollen from a different species from developing a pollen tube and fertilizing its eggs. This is an example of what kind of reproductive isolation? a. pre-zygotic, behavioral isolation b. pre-zygotic, temporal separation c. pre-zygotic, lock and key d. post-zygotic, temporal separation e. post-zygotic, ecological separation

c. pre-zygotic, lock and key

monophyletic group

contains an ancestor and all of its descendants

7) The Galapagos finches flew from mainland South America and evolved into different species that can no longer interbreed. This is due to the idea of a) Vicariance b) Cladogenesis c) Anagenesis d) Dispersal

d) Dispersal

1) Which of the following animal's DNA contains the most junk sequencing? a) E. Coli b) Yeast c) Clams d) Humans

d) humans

14. The phylogeny below represents a hypothesis for the evolutionary relationships among major groups of plants. If it is correct, in what order should we predict to find the fossils of these groups, in order from oldest to youngest? a. flower group, conifer group, ferns, moss group b. conifer group, ferns, moss group, flower group c. ferns, moss group, conifer group, flower group d. moss group, ferns, daisy e. ferns, conifer group, moss group

d. moss group, ferns, daisy

The probability that an ancient species will be represented in the fossil record is a function of: a. the properties of the organisms themselves, such as whether or not they make hard skeletons. b. the properties of the environments in which they live, such as whether or not burial was likely. c. the properties of the climate in which they live, such as how warm or cold it was. d. the properties of the organisms themselves and the environments in which they live. e. All of the answer options are correct.

d. the properties of the organisms themselves and the environments in which they live

progenesis

development that results in speciation through precocial maturation resulting in adults with larval phenotypes adult with juvenile or larval traits

allometric growth

difference of relative rates of growth for different parts of the body

Lysozyme

digests bacterial cell walls

DNA sequencing

direct comparison of the genetic code

Changes in environment

due to catastrophes (e.g. comet or asteroid) due to changes in land masses

Which of the following is NOT a condition of the Hardy-Weinberg equilibrium? a. No differences in the survival and reproductive success of individuals b. No migration c. No mutation d.Random mating e. All of the conditions listed ARE conditions of the Hardy-Weinberg equilibrium

e. All of the conditions listed ARE conditions of the Hardy-Weinberg equilibrium

With few exceptions, we can't use observable traits to measure genetic variation in populations because: a. observable traits don't vary enough among individuals to measure b. we can't identify enough observable traits to be useful, even if they could be measured c.many traits are encoded by large numbers of genes. d.observable traits are products of the environment as well as the genome e. many traits are encoded by large numbers of genes, and observable traits are products of the environment as well as the genome Score: 1 of 1

e. many traits are encoded by large numbers of genes, and observable traits are products of the environment as well as the genome

Hox gene evolution is an important part of evolutionary process because a. They reveal how small mutations can result in large phenotypic change b. Many have gone through gene duplication allowing duplicate copies to evolve c. They serve a regulatory role that controls rates of development of the phenotype d. They are homologous among distantly related taxa e.All of the above

e.All of the above

Adaptations

evolutionary modifications that improve the chances of survival and reproductive success

Preadaptations or exaptations

evolved for one function, adopted for another Co-opting one developmental pathway for another function shift in the function of a trait during evolution

Directional Selection

extreme forms at either end of the distribution have higher fitness average shifts to the left or the right while the variance does not change associated with environmental change e.g. human height, beak width in Galapagos finches

Derived

features that arose within the group under study - synapomorphies- shared derived characters

Ancestral

features that were present in the ancestors of the group pleisomorphies- ancestral characters

trace fossils

foot prints, burrows, leaf impressions - can infer behavior and ecology

Gene duplication

from part of gene to entire genome - functional duplicate copies - more transcript Pseudogenes - functionless Change in function in one copy, while other can evolve rapidly Gene families - a group of genes with related function

Orthologs

genes in different species that evolved from a common ancestral gene by speciation. Normally, orthologs retain the same function in the course of evolution

Tip

group living today or extinct

Taxon (pl. taxa)

group of related organisms

diploid organisms

have two alleles for each gene locus

Allele Frequencies

identify the proportion of each allele at a locus in a population - 0 to 1

Non random mating

inbreeding - mating between closely related individuals causes accumulation of deleterious alleles inbreeding depression assortative mating - mating between individuals of similar phenotypes increases homozygosity

Stabilizing Selection

intermediate forms have higher fitness and are favored by selection does not change the average value for a trait but decreases the variance contributes to stasis e.g. human neonatal weight, gall size in Eurosta solidaginis

Species

kind or appearance taxonomist - based on morphological, physiological, biochemical differences Biological Species Definition-a population or group of populations with the potential to interbreed and produce viable offspring Conspecifics - members of a species

DNA-DNA hybridization

measures the degree of genetic similarity between pools of DNA sequences. It is usually used to determine the genetic distance between two species

Outgroup

members of a closely related group that are not within the group of interest

Restriction mapping

method used to map an unknown segment of DNA by breaking it into pieces and then identifying the locations of the breakpoints. This method relies upon the use of proteins called restriction enzymes, which can cut, or digest, DNA molecules at short, specific sequences called restriction sites.

petrification

minerals in the groundwater seep into tissue

Recombination

most important source of variation the unique combining of different alleles during meiosis gametes produced are random mixes of one of each homologous chromosome crossing over shuffles alleles on chromosomes sex shuffles alleles - recombination

Parsimony

most likely explanation is one that implies the least amount of change

Neutral Theory

most mutations are selectively neutral - genetic drift important

epistasis

multiple loci acting on a single trait e.g. height, color patterns

Synonymous or silent substitution

no effect on phenotype

Genetic Drift

nonadaptive changes in the gene pool due to chance random sampling error increases with decreasing sampling size smaller populations are more likely to experience changes in allele frequencies due to drift bottleneck effects - disasters reduce population size resulting in a non-representative sampling of the original gene pool - reduces genetic variability founder effects - colonization of a new habitat by a few or single individual from the parent population resulting in a decrease in genetic variation

The evolutionary history of a group of organisms is called a ____________.

phylogeny

Interbreeding groups of organisms of the same species living in the same geographical area are called?

population

Branch

population through time

Prezygotic Barriers

prevent the fertilization and the formation of a zygote a) spatial/habitat isolation individuals that live in different places in the environment E.g. Rhagoletes flies - hawthorns and apples Incipient species b) Temporal isolation breeding at different times of the year e.g. eastern and western spotted skunk c) behavioral isolation differences in behavior prevent matings e.g. many closely related bird species d)mechanical isolation - anatomical incompatibility e.g. hemipenes of closely related snake species e) gametic isolation - failure to form a zygote e.g. many aquatic species with external fertilization

Postzygotic Mechanisms

prevent the zygote from developing into a fertile adult a) hybrid zygote abnormality - developing zygote dies due to genetic incompatibility e.g. Rana (frogs) b) hybrid sterility - hybrid offspring are not fertile e.g. mule c) hybrid breakdown - F1 hybrids are fertile, but F2 are not e.g. cotton species

The geological timescale was first developed using the fossil record, but this provided only a system of relative dating; absolute dates weren't established until the discovery of ____________.

radioactivity

Paralogs

related through duplication evolve new functions, even if these are related to the original one

Substitution

replacement of nucleotide base Natural selection would reduce genetic variation

sympatric speciation

reproductive isolation that occurs within the parent population's range Instantaneous speciation Polyploidy - an increase in the number of chromosomes Autopolyploidy - individuals of the same species that produce 2n gametes Allopolyploidy - two different species resulting in (2n+x) offspring Asexual or vegetative reproduction - reproduction without exchange of gametes Separation of the populations is not a physical barrier, but differences in environmental conditions or behavior The role of natural selection is stronger then the effect of gene flow maintaining reproductive isolation - disruptive selection Heavy metal tolerance in plant species

Evolutionary reversal

reverting back to the ancestral condition

homology

similarity derived through common ancestry (e.g. legs in horse and lizard) -results in synapomorphies

Analogy

similarity in function but not evolutionary origin

homoplasy

similarity in function due to convergent evolution - independent evolutionary events that have led to similar phenotypes parallel evolution - similar developmental processes in distantly related taxa Results in traits that do not reflect the evolutionary history - thus uninformative

pleiotropy

single allele affects multiple traits

paedomorphosis

speciation that has resulted from the retention of larval characteristics relative to the parent species

Vicariance

splitting of geographic range into discontinuous parts by formation of physical barrier

Tree

summary of data on the evolutionary history of a group

Phenetics

taxa grouped based on measured similarities and differences (without taking into consideration homology)

Cladistics

taxa grouped based on synapomorphies (shared-derived characters)

gene pool

the aggregate of genes in a population the stock of different genes in an interbreeding population

Molecular Clocks

the average rate at which a species' genome accumulates mutations, used to measure their evolutionary divergence and in other calculations. The more essential a molecule is for function, the slower the rate of evolution natural selection vs. drift Cytochrome c vs. the D-loop in mtDNA Clocks must be calibrated to the molecule that is being used. Based on a constant mutation rate, the time since divergence can be estimated by the amount of sequence divergence

phenotypic plasticity

the phenotype depends on the environment in which the organism is raised The specific trait is not directly heritable but the ability to change phenotype may be

Natural Selection

the process by which better adapted organisms are more likely to survive and become the parents of the next generation

Disruptive Selection

variants at both ends of the distribution have higher fitness than intermediate forms no change in the average but increases the variance rare can result in new species