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146 Cards in this Set

  • Front
  • Back
The definition of Biological Evolution
Chane over time in the proportions of individual organisms that differ genetically in one or more traits
Difference between micro and macro evolution
Micro is small scale including the change in proportions of individuals that alter characteristics of species
Macro is large scale including the change in proportions of species that changes diversity of taxonomic groups
Biological phenomena that require evolutionary explination (2)
Diversity of organisms and Change in organisms over time
Difference between proximate and ultimate explanations for biological phenomena
Proximate answers questions of "What" and "how" (Functional Bio)
Ultimate answers questions of "Why" (Evolutionary Bio)
How are Ecology, Evolution and Genetics related?
All evolutionary processes involve changes in frequencies of different genes. As well as the ecological interactions between organisms and their environment
Define Adaptation
a genetically-determined trait that confers functional advantage over alternate traits in a given environment
What is an important part of evolution and what causes it?
Variation is needed for evolution to exist. Variation is caused by genetic differences causing phenotypic differences.
The difference between Qualitative and Quantitative variation
Qualitative is discrete, with one or two morphs and determined by a few alleles at a loci.
Quantitative is continuous between a max and min value. Usually determined by many alleles at many loci.
What are the five main processes that change allele and genotype frequencies?
Mutation, Migration (intorduction of new alleles),
Genetic drift (randomly altering frequency within a population),
Natural Selection (non-random altering of alleles),
Mating patterns (affet organization of alleles into genotypes)
Conditions under which Hardy-Weinberg Theory applys...(7)
1. Diploid, sexual organism
2. Non overlapping generations
3. Large populations
4. Random mating
5. No migration
6. No mutation
7. No Natural selection (for gene of interest).
Hardy-Weinberg equation and what does it represent
p² + 2pq + q²= 1 will be the proportions of AA, Aa and aa (respectivly) for a population at equilbrium
What is the multiplication rule
The probability of two events occuring at the same time, when these events are independent of one another, is the product of the two probabilities
To determine q, you can take the square root of q² ONLY FOR..
Populations where H-W conditions hold.
If it is not known if H-W conditions hold, q or p can be estimated using...
q = (2nAA + nAa) / (2N)
T or F
Once H-W equlibrium is reached, it will persist as long as H-W conditions hold
True
Define and describe "Random Mating"
Mating occurs ramdomly if females and males are randomly selected so that the expected frequency of each genotype in the offspring is the product of the frequency of the parental alleles.
The difference between Positive and Negative assortative mating and results
Positive: Mating between individuals sharing a phenotypic trait. Increaes homozygosity
Negative: mating between individuals of opposite phenotypes. Increases heterozygosity.
What is Inbreeding, what are the effects on allele frequencies?
Is mating between genetic relatives. It increases homozygosity for ALL gene loci. By itself, it does NOT affect allele frequencies.
Define genetic load
It is the number of deleterious recessive alleles in a population.
Define inbreeding depression
Occurs with high genetic load where inbred individuals generally survive and reproduce less successfully than outbred individuals.
Describe 2 methods of inbreeding avoidance
(1) Dispersal from place of birth
(2) Incest avoidance by way of making it "Taboo"
Define/Describe random mutations
Mutation is an error in replication of a nucleotide sequence that produce random changes in gene frequency. Ultimate source of new genetic forms.
Is mutation a powerful enough agent to change gene frequencies on its own?
NO, without mutation all evolution would stop, but it does not drive evolution on its own.
What is the effect of migration and what 2 things determine the effect?
The result of migration is GENE FLOW and the effect varies with
(1) rate of migration
(2) differences in allele frequencies
Explain the concept of "gene pool"
Is all of the alleles present in a population at one time. Reproduction can be viewed as "sampling process" of this pool
Define Genetic Drift and what it can result in
changes in allele frequencies because of random variation in reproduction and survival. In absence of other processes it results in fixation or loss of the allele.
In the absence of Natural selection, genetic drift determines...
The fate of new alleles created by mutation.
Characteristics of Natural Selection (4)
Causes non random changes,
Depends on both genotype and phenotype
Involves ecological interactions
The only process that results in adaptation.
Define fitness
The average contribution of genes to the next generation by a particular phenotype in a particular environment. The ability to survive and reproduce.
Necessary and sufficient conditions for Natural Selection (3)
(1) Phenotypic variation
(2) Fitness difference associated with different phenotypes
(3) Inheritance
Is Natural Selection "goal directed"?
Natural selection is NOT directed to a goal, it is an Editor not a writer
Describe Viability Selection
Single autosomal locus with two alleles, All H-W conditions hold (except the one about selection) Non-overlapping generations and all individuals have the same reproductive fitness.
The difference between relative and absolute values of fitness
Relative fitness is the comparison of an individuals fitness relative to the mean fitness.
Major factors responsible for change in relative fitness of a genotype over time
A change in habitat or environment (yeilding a need for change in traits)
Who described Natural Selection first?
Charles Darwin and Alfred Wallace
Define and describe "Random Mating"
Mating occurs ramdomly if females and males are randomly selected so that the expected frequency of each genotype in the offspring is the product of the frequency of the parental alleles.
The difference between Positive and Negative assortative mating and results
Positive: Mating between individuals sharing a phenotypic trait. Increaes homozygosity
Negative: mating between individuals of opposite phenotypes. Increases heterozygosity.
What is Inbreeding, what are the effects on allele frequencies?
Is mating between genetic relatives. It increases homozygosity for ALL gene loci. By itself, it does NOT affect allele frequencies.
Define genetic load
It is the number of deleterious recessive alleles in a population.
Define inbreeding depression
Occurs with high genetic load where inbred individuals generally survive and reproduce less successfully than outbred individuals.
Describe 2 methods of inbreeding avoidance
(1) Dispersal from place of birth
(2) Incest avoidance by way of making it "Taboo"
Define/Describe random mutations
Mutation is an error in replication of a nucleotide sequence that produce random changes in gene frequency. Ultimate source of new genetic forms.
Is mutation a powerful enough agent to change gene frequencies on its own?
NO, without mutation all evolution would stop, but it does not drive evolution on its own.
What is the effect of migration and what 2 things determine the effect?
The result of migration is GENE FLOW and the effect varies with
(1) rate of migration
(2) differences in allele frequencies
Explain the concept of "gene pool"
Is all of the alleles present in a population at one time. Reproduction can be viewed as "sampling process" of this pool
Who first described Natural Selection
Charles Darwin and Alfred Wallace
Define Natural Selection and its components(4)
Is the differential genetic contributions by particular phenotypes to the next generation. Causes non-random changes, depends on genotype and phenotype, involves ecological interactions, and results in adaptation.
Define Fitness
The average contribution of genes to the next generation by a particular phenotype in a particular environment. The ability of a individual to survive and reproduce
Necessary and Sufficient conditions for Natural Selection (3)
(1) Phenotypic variation
(2) Fitness difference associated with different phenotypes
(3) Inheritance (genetic response)
Describe Viability Selection
A single autosomal locus with two alleles, all H-W conditions hold (except for one about selection). Phenotypes differ in reproductive success.
What is the equation for mean fitness?
W = p²WAA + 2pqWAa + q²Waa
Define relative fitness and its equation
Is the fitness of a genotype compared to the mean fitness of the population. WAa/W
Does natural selection increase or decrease mean fitness in a population
Natural selection increases mean fitness over time.
What is the outcome when there is complete dominance with the dominant allele advantageous (WAA = WAB > WBB)
Natural selection will push population to point where Fixation of allele A. (p=1 q=0)
What is the outcome when there is complete dominance with recessive allele advantageous (WAA = WAB < WBB)
Natural selection will push population to point where fixation of allele B (p=0 q=1)
What is the outcome when Heterozygote advantageous?
WAB> WAA and WAB> WBB
Balanced polymorphism where stable equlibrium where 0<p<1
What is the outcome when there is a heterozygote disadvantage?
WAB< WAA and WAB< WBB
An unstable equilibrium, selection will not result in best possible outcome. Will result in fixation of A or B depending on random factors.
What happens once fixation of an allele is reached or polymorphism is reached
Allele frequencies will not change anymore. Natural selection will act to maintain balanced polymorphism but no further evolution.
Is Natural selection, by itself, sufficient for long term evolution
No.
What does the rate of evolution by natural selection depend on?
(1) a phenotypes dominance
(2) its current frequency in a population.
What speed of evolution do
(a) dominant
(b) recessive
allels have when they are rare
(a) Dominant alleles have RAPID evolution when rare
(b) Recessive alleles have SLOW evolution when rare.
What is Quantitative Variation
Variation between a max and min value with phenotypes at most values inbetween.
What does a normal distribution of variation look like?
A symmetrical bell shaped curve. The peak represents the mean and the width represents the variance.
What are the causes of continuous phenotypic variation (2)
(1) Phenotypic plasticity (same genotype produces different phenotypes)
(2) Complex genetic control (phenotype determined by several gene loci)
Describe Additive genetic effects
The properites of genes that are passed on to the next generation
Can the basic rules of Mendelian genetics be applied to quantitative traits?
No, quantitative traits use statistical procedures to analyze complex patterns.
What are the 3 components of Phenotypic variation?
(1) Additive variation - under genetic control
(2) Interaction among alleles - Dominance (same locus) or epistasis (different loci)
(3) environmental - environmental influences.
What are common garden experiments? and what do they tell you
Expose different genotypes to same environment to determine if variation is product of genetic effects
What are clone studies and what do they tell you/
Expose individuals with identical genotypes to different environments to determine if variation is product of environmental effects.
What is Additive Genetic Variation?
It is the only component that is passed on to offspring.
What is heritability?
h² represents the proportion of total phenotypic variation determined by additive genetic effects. Specific to environment.
How do you calculate heritability?
h² = R/S where
R = Mean offspring - mean parents
S = Mean selected - Mean parents
"Mid parental regression" graphs
h² is the slope of relationship between offspring value and mid-parent value. A line of slope 1 means all variation is due to additive traits.
What is truncation selection
The isolation of individuals with an extreme value. To test for heritability (usually).
Describe Directional Selection
Selection gradient either increases or decreases over a range of phenotypes. 'Pulls' phenotype mean in one direction.
Describe Stabilizing selection
Humped selection, individuals with extreme phenotypes leave fewer offspring. Results from opposing selection pressures. Mean phenotype does not change.
Describe Disruptive selection
Individuals with intermediate phenotypes leave fewer offspring. Effectivness depends on mating patterns. Reinforced by positive assortative mating.
What is the example Mr. boring used to describe Disruptive Selection
Goldenrod Gall Fly where there were two species of plants and one species of fly with two different phenotypes. The flies specilized on certian types of plants causing disruptive selection to occur.
All modes of selection have a deleterious effect on..
Additive genetic variation, which makes selection possible.
Describe frequency dependent selection and the positive and negative effects.
Occurs when the fitness of an individual depends on the relative frequency of other phenotypes in the population.
(1) Positive = majority advantage
(2) negative = minority advantage
Frequency dependent selection and result in...
Evolutionary stable state when some combination of phenotype frequencies may exist where all phenotypes have same fitness.
Name and describe the 4 types of social interactions...
(1) Spite - A and R lose
(2) Selfishness - A benifits and R loses
(3) Altruism - A loses and R benifits
(4) Cooperation - A and R benifit
Describe Inclusive fitness
It is the sum of direct fitness and indirect fitness.
Direct fitness - genetic contribution to future generations.
Indirect fitness - Contribution of an altruistic individual
Describe Kin selection
is natural selection based on inclusive fitness. It depends on genetic relatedness between altruistic actor and recipiant of altruistic act.
What is the coefficient of genetic relatedness?
R = the probability that two relatives posess alleles at a given locus that are identical by descent. Determined by amount of genetic material act gives or has in common with recipiant.
T or F:
Distantly related individuals share fewer genes by descent than do close relatives?
True
Describe Hamiltons rule
Hamilton says that altruism will evolve if:
R > (C/B) the relatedness is greater than the ratio of cost to benifit
What are the implications of Hamiltons Rule? (3)
Altruism is most likely to evolve when
1. High R
2. Small C
3. Large B
What are the three characters of Eusociality and what are some examples?
1. Cooperative rearing of young
2. Generations overlap
3. Reproductive divison of labor.
Hymenoptera (bees and ants) are very eusocial organisms. Also in termites and naked mole rat
What genetic system allowed the Hymenoptera to easily evolve altruism?
Haplodiploidy, where by unfertilized eggs are male and fertilized eggs are female. Creates differences in relatedness.
What is R with Haplodiploidy?
Mother--> Daughter 0.5
Daughter --> Mother 0.5
Mom --> Son 0.5
Son --> Mom 1
Dad --> Daughter 1
Daughter --> Dad 0.5
Dad --> Son 0
What is the consequence of haplodiploidy?
Females are more closely related to their sisters (R=0.75) than they are to their own offspring (R=0.5)
Alarm calling is an example of?
Kin selection and defense
What are the 4 sources of fitness differences?
1. Survival (viability selection)
2. Gamete production (fecundity)
3. Mating ability (gamete exchange)
4. Fertilizing ability (gamete fusion)
What is sexual selection?
Phenotypic selection based on differences in mating and fertilizing ability.
What is sexual dimorphism?
Differences between sexes in physical characteristics other than primary sex organs.
Describe Reproductive Investment
The amont of time and resources devoted to creating and sustaining offspring.
What are characteristics of the High investment sex
They are limited primarily by avaliability of resources for production of gametes or offspring. usually the female.
What are characteristics of the Low investment sex
Limited primarily by mating opportunities. Usually male.
What type of variation is seen in reproductive sucess.
Since "Sex is cheap" the low investment sex usually has more offspring than does the high investment sex.
Describe Intra-sexual selection
Competiton among members of the same sex for opportunities to mate or to fertilize gametes.
What are the three instances where competition for sex may occur?
1. Before mating (tertitory)
2. After mating (sperm competiton)
3. After birth (infanticide)
Describe Inter-sexual selection and what it is based on (2)
Mate choice, High investment sex benifits from being choosy about mate. Based on parental investment and good genes.
The reversal of sex roles is found in two grops
Some birds and many fish
Natural selection only involves phenotypes not genotypes (T OR F)
False, both phenotypes and genotypes.
Fitness of phenotype depends on environment, specifically 3 things...
1. physical/chemical environment
2. other species
3. other individuals of the same species.
The selection gradient determines the _______ and ______ of natural selection
Direction and Intensity.
Microevolution depends on the combined effects of ... (3)
1. Mutation
2. Genetic drift
3. Natural selection
What are the 4 important characteristics of a species?
1. A collective group of individuals
2. Common ancestory/geneology
3. Interbreeding via a common gene pool
4. Genetic integrity (no mixing of gene pool with other pools)
Who is MR. Boring?
Dr. Lein.. HAHA snore!
What is the Biological species concept?
Species are groups of actually or potentially interbreeding natural populations that are reproductivley-isolated from other such groups (Ernst Mayr)
Describe speciation
A sing species splits or speciates resulting in two daughter species. It is the ultimate source of biodiversity.
Y OR N
Can microevolutionary processes explain speciation and biodiversity?
YES!
What is gene flow
Interbreeding between populations movement of alleles between populations mixing genetic material.
Define Clade
A group of species that is descendant from the same ancestral species.
What is a pre-zygotic barrier?
Stops the exchange of genetic information before fertilization
What are the 4 types of pre-zygotic barriers?
1. Ecological seperation - temporal or spatial seperation
2. Behavioral seperation - positive assortative mating at species level
3. Mating w/o tranfer of gametes
4. Gamete transfer w/o fertilization - physiological incompatibility between gametes
What is post-zygotic barriers and what are the two types?
Occurs after fertilization
1. Hybrid inviability - failure of hybrid offspring to survive and reproduce
2. Hybrid sterility - Hybrids are viable but sterile (DONKEY! :D)
Describe Allopatric distribution and Allopatric Speciation
Populations are seperated geographically, seperation is larger than dispersal distances therefore prevention of gene flow and speciation result
Allopatric speciation via Vicariance
A split of a continuous distribution into parts that are large (ignore genetic drift) Natural selection acts on different groups to produce different adaptations.
Common causes of Vicariance
Glaciation and sea level changes, climatic changes, geological processes (mountain building) and continental drift.
Allopatric speciation via Peripheral isolation
The colonization of unoccupied habitat isolated from main range by relativly few individuals.
Peripheral isolation results in... (2)
A population bottleneck may effect genetic composition via
1. Founder effect - colonists do not have complete genetic diversity
2. Genetic drift - population is small so may change genetic structure.
What is sympatric speciation
Populations overlap geographically by speciate because of reproductive isolation between two segments
Sympatric speciation via Polyploidy
Usually occurs in plants, mating between two species creates invaluble hybrid but doubling of chromosomes restores fertility.
Describe sympatric speciation via Disruptive selection
Intermediate phenotypes have reduced fitness, Positive assortitive mating allows process. Result is reproductive isolation of phenotypes
What inhibits sympatric speciation via disruptive selection
Random mating promotes gene flow between "phenotypes"
What animal is a good example of sympatric speciation via disruptive selection?
Apple maggot fly. There are now two forms that differ at several gene loci. Preferences for host plant resulted in positive assortative mating.
Polyploidy after Hybridization results in...
Instant speciation
(T OR F)
All similarities or shared characteristics indicate relatedness
False, not all!
Define Shared ancestral characters
Phylogenetically informative?
Evolved in a distant ancestor and are shared by many descendant taxa.
* Not phylogenetically informative.
Define Shared Derived characters
Phylogenetically informative?
Evolved in the common ancestor of TWO taxa.
* Phylogenetically informative
Define Analogous characters
Phylogenetically informative?
Simular because of convergent evolution
*Phylogenetically misleading
Define Unique derived characters
Phylogenetically informative?
Not shared with any other taxon
*Not phylogenetically informative.
When phylogeny is described in a matrix, what do 1 and 0 mean?
1 - character present
0 - character absent.
What is Ockham's Razor and the Principle of Parismony?
When confronted with two or more equally plausible hypotheses choose the simpler explination. Phylogenetic hypothesis with the fewest transitions between character states.
Does the order of branching on a phylogenetic tree indicate any information about evolutionary history?
NO
Evolutionary relatedness is depicted by...
Distance along branches
Explain Morphology vs Molecules
Morphology only offers limited number of shared derived characters vs dna offers many. But DNA can not apply to fossils. Thus the two can create different trees.
Define Monophyletic
A taxon comprised of all species derived from a common ancestor including the ancestor
Define Paraphyletic
A taxon derived form a single common ancestor but does not include all descendants of that ancestor.
Define Polyphyletic
A taxon composed of members that do not share a recent common ancestor
Natural classification includes...
Only monophyletic taxa.
Define and explain adaptive radiation
Evolutionary divergence of a single phylogentic lineage into a variety of different adaptive forms. Usually over a short period of time in a environment with few competitors.
What example was used, in detail, to describe adaptive radiation?
The Caribbean Anolis (Lizard). Repeated speciation on different islands Fell into different ecomorphs due to different ecological niches.
In the case of the Caribbean Anolis ecomorphological resemblance among islands resulted from...
Convergent evolution. Analogous rather than homologous traits.