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64 Cards in this Set
- Front
- Back
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Variance |
the deviation or spread of values around the mean |
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Phenotypic variance |
the variance associated with an observed phenotypic trait. =genetic variance+environmental variance |
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Response to Selection |
the mean change in a trait from one generation to the next in response to selection |
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Heritability in the narrow sense |
The proportion of phenotypic variance is due to additive genetic differences |
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Dioecious |
Species with separate male and female individuals |
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Hermaphroditic |
individuals that can produce both types of gametes |
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Vegetative propagation |
offspring arise non-sexually from a group of cells |
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Parthenogenesis |
offspring develop from a single cell |
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Apomixis |
Meisos is suppressed and offspring develop from an unfertilized egg |
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Mullers Ratchet |
In asexual species new deleterious mutations have no way to be purged. Occurs slowly by may explain higher extinction rate in asexual taxa |
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Advantages of Sex |
mullers ratchet Adaptation to the changing environments |
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Sex ration |
proportion of males in a population |
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Sexual Selection |
selection arising from variability in finding mates |
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Runaway Sexual selection |
Coevolution of male trait and female preference so both increase in frequency
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Sensory Bias |
When a certain trait stimulates the sensory system, invoking a biological response Mitts Chickens |
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Antagonistic Coevolution |
conflict between the two sexes that can harm one or both sexes in order to increase success Drosophila sperm is toxic to females |
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Species Concept |
criterion describing what constitutes a species |
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Biological Species Concept |
Species are groups of interbreeding natural populations that are reproductively isolated from other groups |
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Phylogenetic Species Concept |
Irreducible cluster of organisms that is distinct from other clusters and share a common evolutionary history |
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Cohesion Species Concept |
Species is the most inclusive population of individuals having the potential for phenotypic cohesion through intrinsic cohesion mechanisms.
emphasizes genetic or demographic exchangeability |
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Premating barriers |
prevent or reduce likelihood of other species transferring gametes Ecological isolation Temporal Isolation Behavioral Isolation |
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Postmating, prezygotic barriers |
Gametes unable to unite Sperm cannot reach egg |
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Postzygotic Barriers |
non-viability of zygotes Hybrid Inviability Hybrid Sterility |
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Hybridization |
When genetically distinct taxa produce offspring by interbreeding Common in plants Rare in mammals |
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Hybrid Vigour (heterosis) |
When hybrid offspring have increased fitness relative to their parents |
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Hybrid Zones |
localized area where hybrid offspring are produced |
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Class of Hybrid Zones: Primary and Secondary |
Primary- Zones that develop as continuously distributed populations are diverging Secondary-zones that develop when species have diverged in isolation and they come into secondary contact |
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Introgression |
Transmission of genes or alleles from one species to another |
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Fate of hybrid zones |
1. Maintained 2. Isolated and speciated 3. Merge into one species 4. Hybrid speciation |
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Speciation |
the formation of a new species from a pre-existing species |
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Allopatric Speciation |
Evolution of reproductive barriers in populations that are geographically isolated |
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Vicaraiance |
Divergence of two Large populations Type of allopatric |
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Peripatric Speciation |
divergence of a small population from a large population. Type of allopatric |
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Parapatric Speciation |
evolution of reproductive barriers among neighboring populations with limited amounts of gene flow |
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Sympatric speciation |
evolution of reproductive barriers in an initially random mating population occupying a single location |
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Evidence for Allopatric Speciation |
Isolation by distance Concordance of species boundaries- Panama Absence of sister species where there is limited habitat or ecological diversity |
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The origin of Incompatibility
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Reproductive barriers among allopatric species based on changes at two or more loci with complementary effects on fitness |
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Reinforcment of Isolation |
evolution of enhanced reproductive isolation due to natural selection for greater isolation. Favors pre-zygotic isolation |
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Difficulties of Sympatric Speciation |
Antagonism between selection and recombination Coexistance |
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Models of Sympatric Speciation |
Disruptive selection/Assortive Mating Rapid ecological adaption-ecological speciation |
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Speciation by Polyploidy |
Can be from auto or allopolyploidy Gives rise to new organism that cannot mate with parent species |
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Recombinational Speciation |
The formation of a new hybrid species when both parents have the same chromosome number (homoploid hybrid speciation), then becomes distinct species |
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Rate of Speciation |
Vary widely among groups Time required for isolation to evolve Biological speciation interval- time between origin of new species and when that species splits again |
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Coevolution |
reciprocal genetic change in interacting species due to natural selection imposed by each on the other Competition Mutualism |
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Specific coevolution |
Two species evolve in direct response to each other |
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Guild Coevoltuion |
when several species are coevolving and their effects are not independent |
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Escape and radiate coevolution |
a species evolves a defense against enemies and is then able to diversify |
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Concordance |
aaaaa |
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Exon Shuffling |
new combinations of domains created by non-homologous recombination |
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Neofunctionalization |
A new gene created by gene duplication gets a new function while the other keeps the ancestral trait |
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Subfunctionalization |
Duplicate genes become specialized for a subset of functions preformed by the ancestral gene |
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Evolutionary developmental Biology |
study of how development has evolved in terms of development and evolutionary processes |
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Homeobox Genes |
class of genes that control patterning of specific body structures Blueprint genes All HOX genes are part of a single gene family All animal taxa contain hox |
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Transcription factors |
proteins that regulate the transcription of other genes |
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Biological homology concept |
the idea that features may be homologous among species at one level (i.e. phenotypic) but not at another (i.e. genetic or developmental) |
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Developmental pathways |
hierarchical networks that involve multiple genes and products |
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The evolution of New function |
1- when there is no gene duplication or change: new function may arise if active after ancestral period of expression 2-When duplication or change: 1 pathway in one region can be turned on in different region, or gene duplication |
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Microevolution |
evolutionary processes occurring within species |
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Macroevolution |
evolutionary processes occurring above the species level |
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Puncutated equilibrium |
long periods of little change interupted by rapid change |
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Stasis |
lack of evolutionary change for a long time |
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Gradualism |
gradual change from one phenotype to another |
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Saltation |
a sudden jump in phenotype |
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Pathways for novel features to originate |
1. Feature originates as a new structure or modification of an existing structure 2 Features is a developmental byproduct 3. Ancestral function or feature may become accentuated 4. Decoupling of functions 5. Duplication with divergenece 6. A change in function altering selective regime |
