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evolution
bio 2486A
68
Biology
Undergraduate 2
12/12/2011

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Term
adaptation
Definition
a trait that increases the ability of an individual to survive or reproduce when compared with individuals who do not have the trait.
Term
adaptive radiation
Definition
a trait that increases the fitness of its bearer
Term
additive effect
Definition
the contribution of an allele to make to the phenotype independent of the identity of the other alleles at the same or different loci
Term
additive genetic variation
Definition
difference among individuals in a population that are due to the additive effect of genes
Term
agent of selection
Definition
any factor that causes individuals with certain phenotypes to have, on average, higher fitness than individuals with other phenotypes
Term
alleles
Definition
variant form of a gene, or variant nucleotide of at a particular locus
Term
allopatric model
Definition
the hypothesis that speciation occurs when populations become geographically isolated and diverge because selection and drift act on them independently
Term
allopatry
Definition
living in different geographic areas
Term
allozymes
Definition
distinct forms of an enzyme, encoded by different alleles at the same locus
Term
altruism
Definition
behaviour the decreases the fitness of the actor but increases the fitness of the recipient
Term
anagenesis
Definition
descent with modification but no speciation
Term
ancestral
Definition
describes a trait that was possessed by the ancestor of the species on a branch of the evolutionary tree, in contrast with derived
Term
antibiotic
Definition
a chemical, typically extracted from a microorganism that kills bacteria by disrupting a particular biochemical process
Term
antigenic site
Definition
a portion of a protein that is recognized by the immune system and initiates a response
Term
assortative mating
Definition
occurs when individuals tend to mate with others possessing the same genotype or phenotype
Term
average excess
Definition
the average excess it the mean difference between individuals carrying allele a and the mean fitness of the rest of the population. if the mean fitness of allele a > the rest of the population, allele a will rise in frequency
Term
back mutation
Definition
a mutation that reverse the effect of a previous mutation, typically occurs to restore the effect of a loss of function mutation
Term
background extinction
Definition
extinctions that are not part of mass extinction events, thought to be due to typical types and rates of environmental change or species interactions as opposed to major environmental changes that occur in mass extinctions
Term
bateman gradient
Definition
the slope of best fit line relating reproductive success to mating success, measuring the strength of sexual selection
Term
blending inheritance
Definition
the hypothesis that heritable factors blend to produce a phenotype and are passed on to offspring in this blended form
Term
bootstrapping
Definition
in phylogeny reconstruction, a technique for estimating the strength of the evidence that a particular node in a tree extists. bootstrapping values range from 0 - 100%, with higher values indicating stronger support.
Term
bottleneck
Definition
a large-scale but short term reduction in population size followed by an increase in population size
Term
broad-sense heritability
Definition
that fraction of the total phenotypic variation in a population that is caused by genetic differences among individuals
Term
catastrophism
Definition
in geology, the view that most or all landforms are the product of catastrophic events, such as the flood described in the bible
Term
cenancestor
Definition
the last common ancestor of all extant organisms
Term
chromosome inversion
Definition
a region of DNA that has been flipped, so that the genes are in reverse order; results in lower rate of crossing over and thus tighter linkage among loci with the inversion
Term
clade
Definition
the set of species descended froma particular common ancestor; syn. with monophyletic group
Term
cladistic
Definition
a classification scheme based on the historical sequence of divergence events (phylogeny); also used to identify a method of inferring phylogenies based on the presence of shared derived character; syn with synapomorphies
Term
cladogram
Definition
an evolutionary tree reflecting the results of cladistic analysis
Term
cline
Definition
a systematic change along a geographic transect in the frequency of genotype/phenotype
Term
codon
Definition
a set of 3 base pair in DNA that specifies a particular amino acid - carrying tRNA
Term
coefficient of breeding (F)
Definition
the probability that the alleles at any particular locus in the same individual are identical by descent from a common ancestor
Term
coefficient of linkage disequilibrium (D)
Definition
a calculated value that quantifies the degree to which genotypes at one locus are nonrandomly associated with genotypes at another locus
Term
coefficient of relateness (r)
Definition
the probability that the alleles at any particular locus in two different individuals are identical by descent from a common ancestor
Term
coevolution
Definition
that which occurs when interactions between species over time lead to reciprocal adaptions
Term
common garden experiment
Definition
an experiment in which individuals from different populations or treatments are reared together under identical conditions
Term
comparative method
Definition
a research program that compares traits and environment across taxa and looks for correlations that test hypotheses about adaptations
Term
complementary base pairs
Definition
nucleotides that match up and form hydrogen bonds on opposite strands of a DNA molecule or DNA-RNA duplex. C complements G and A complements T
Term
conjugation
Definition
in bacterial genetics, the transfer of one or more genes from one cell to another via a plasmid that travels through a conjugation tube
Term
constraints
Definition
any factor that tends to slow the rate of adaptive evolution or prevent a population from evolving the optimal value or a trait
Term
convergent evolution
Definition
similarity between speicies that is caused by similar, but evolutionarily independent, responses to a common environmental problem
Term
cryptic species
Definition
species that are indistinguishable morphologically, but divergent in songs, calls, odors or other traits
Term
darwinian fitness
Definition
the extent to which an individual contributes genes to future generations, or an individual's score on a measure of performance correlated with genetic contribution to future generations (such as lifetime reproductive success)
Term
derived
Definition
describes a trait that was not possessed by the common ancestor of the species on a branch of an evolutionary tree, in contrast with ancestral
Term
deuterostome
Definition
a lineage of animals that share a pattern of development, including radial cleavages and development of anus before mouth
Term
differential success
Definition
a difference between the verage survival, fecundity or number of matings achieved by individuals with certain phenotypes versus individuals with other phenotypes
Term
diploblasts
Definition
organism that develops from two embryonic tissue types (ectoderm/endoderm)
Term
direct fitness
Definition
fitness that is due to the production of offspring
Term
direct sequencing
Definition
a research program taking a sample of the genes in an environment used in determining what species are present in that environment, then placing the organisms on a phylogentic tree; syn. with environmental sequencing
Term
directional selection
Definition
that which occurs when individuals fitness tends to increase or decrease with the value of phenotypic trait; can result in steady evolutionary change in the mean value of the trait in the population
Term
disruptive selection
Definition
occurs when individuals with more extreme values have higher fitness; can result in increased phenotypic variation in a population
Term
dominance genetic variation
Definition
differences among individuals in a population that are due to the nonadditive effects of genes, such as dominance; typically means the genetic variation left over after the additive genetic variation has been taken into account
Term
dynamic stasis (or stasis)
Definition
lack of morphological change over a long interval of evolution, despite many short term changes during the same interval, result is no net evolution
Term
ecdysozoan
Definition
a lineage of protosomes distinguished by the presence of molting
Term
effective population size (Ne)
Definition
the size of an ideal random mating population (no selection, migration or mutation) that would lose geneetic variation via drift at the same rate as is observed in actual population
Term
endosymbiosis
Definition
a relationship in which an organism lives inside the body of another or within their cells (mitochondria)
Term
environmental variation
Definition
differences among individuals in a population that are due to differences in the environment they have experienced
Term
epitope
Definition
part of a protein that is recognized by the immune system and elicits an immune response; syn with antigenic site / determinant
Term
eusocial
Definition
describes a social system characterized by overlapping generations, cooperative brood care, and specialized reproductive / nonreproductive castes
Term
evolution
Definition
changes in allele frequency over times
Term
evolutionary stable strategy
Definition
in game theory, a strategy or set f strategies that cannot be invaded by a new, alternative strategy
Term
evolutionary arms race
Definition
that which occurs in response to reduction in fitness by the adaptation of a competitive organism thus causing future evolution in the first organism
Term
evolutionary tree
Definition
a diagram (typically an estimate) of the relationship of ancestry and descent among a group of species or populations; in a paleontolgocial studies the ancestors may be known from fossils, whereas in studies of extant species the ancestors may be hypothetical constructs.
Term
exon
Definition
a nucleotide sequence that occurs between introns and that remains in the messenger RNA after the introns have been spliced out
Term
extant
Definition
living today; opposed to extinct
Term
extended haplotype homozygosity (EHH)
Definition
a measure of the linkage disequilibrium between an allele at a locus of interest and alleles at other loci on the same chromosome. allele a's EHH to a particular distance x is the probability that two randomly chosen chromosomes carrying a will have the same genotype at all marker loci between a and x
Term
fecundity
Definition
the number of gametes produced by an individual usually in reference to the number of eggs produced by a female
Term
fitness
Definition
the extent to whioch an individual contributes genes to future generations, or an individual's score on a measure of performance expected to correlate with genetic contribution to future generations (such as lifetime reproductive success)
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