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Chapter 17
Chapter 17 vocab
43
Biology
Undergraduate 2
11/21/2011

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Term
Taxon
Definition
A population, species, or other group of organisms which a protein or nucleic acid sequence, or set of such sequences, is regarded as representative
Term
Molecular phylogenetics
Definition
The analysis of molecular sequences in order to infer their evolutionary relationships
Term
Fixed
Definition
A mutant allele that replaces all other alleles in the population
Term
Gene Tree
Definition
A graph depicting the genealogical reltionships among a set of alleles of the same gene in one or more species
Term
Distance methods
Definition
Based on the number of differences between each pair of sequences
Term
Parsimony methods
Definition
Systematically searches among all possible gene trees to find those that minimize the number of fixed mutations needed to account for the data
Term
Maximized liklihood methods
Definition
Invokes a theoretical model of how nucleotide or amino acid substitutions occur, and then identifies the gene tree that maximizes the probability of observing the actual data based on the model
Term
Bayesian method
Definition
Uses a generalization of Bayes theorum to infer the relative probability of any gene tree based on prior assumptions about the distribution of possible trees
Term
Distance matrix
Definition
A matrix showing the amount of sequence divergence between all possible pairs of a set of protein or nucleic acid sequences
Term
Neighbor joining
Definition
A method for estimating a gene tree in which pairs of taxa are joined sequentially according to which pair are separated by the shortest distance
Term
Boot strapping
Definition
A common technique for assessing the reliability of a node in a gene tree
Term
Molecular clock
Definition
A condition in which a protein or nucleic acid molecule has the same probability of change per unit time in every branch of a gene tree
Term
Selectively neutral mutation
Definition
A mutation that has no effects on fitness
Term
Pseudogenes
Definition
A DNA sequence that is not functional because of one or more mutations but that has a functional counterpart in the same organism
Term
Orthologous genes
Definition
Genes that are duplicated as an accompaniment to speciation and that retain the same function
Term
Paralogous genes
Definition
Two or more genes that derive from a common ancestral gene through one or more gene duplications followed by sequence divergence
Term
Subfunctionalization
Definition
Specialization of paralogs accompanying loss of functional capabilities
Term
Sub populations
Definition
Geographically widespread species that are subdivided into more or less distinct breeding populations
Term
Gene pool
Definition
A common pool of genetic information
Term
Genotype frequency
Definition
The proportion of organisms that have the particular genotype
Term
Allele frequency
Definition
The proportion of all alleles that are of the specified type
Term
Random mating
Definition
When mating pairs are formed without regard to genotype
Term
Hardy-weinberg principle
Definition
The genotype frequencies expected with random mating
Term
DNA typing
Definition
A procedure in which biological samples of unknown human origin are matched wih their source through the use of polymorphic DNA markers
Term
Inbreeding
Definition
Mating between relatives such as first cousins
Term
Consanguineous maing
Definition
A mating between relatives
Term
Inbreeding coefficient
Definition
The proportionat reduction in H1 compared with the value of 2pq that would be expected with random mating
Term
Identity by descent
Definition
The condition in which two alleles are botb replicas of a single ancestral allele in the past
Term
Mutation 
Definition
The origin of new genetic capabilities in populations by means of spontaneous heritatble changes in genes
Term
Migration
Definition
The movement of individuals among subpopulations within a larger population
Term
Natural selection
Definition
the differing abilities of individuals to survive and reproduce in their environment
Term
Random genetic drift
Definition
the random, undirected cahnges in allele frequency that occur by chance in all populations, but particularly in small ones
Term
Forward mutation
Definition
a change from a wildtype allele to a mutant allele
Term
Reverse Mutation
Definition
A mutation that undoes the effect of a preceding mutation
Term
Equilibrium
Definition
a situation in which the allele frequencies remain constant from one generation to the next
Term
Relative Fitness
Definition
The fitness of a genotype expressed as a proportion of the fitness of another genotype
Term
Selection coefficient
Definition
The amount by which relative fitness is reduced or increased
Term
Viability
Definition
The probability that a newly formed zygote of the specified genotype survives to reproductive age
Term
Fertility
Definition
The average number of offspring produced by an individual of the specified genotype during the reproductive period
Term
Selection-mutation balance
Definition
Equilibrium determined by the opposing effects of mutation tending to increase the frequency of a deleterious allele and selection tending to decrease its frequency
Term
Degree of dominance 
Definition
The extent of which the phenotype of a heterozygous genotype resembles one of the homozygous genotypes
Term
Overdominance
Definition
A condition in which the fitness of a heterozygote is greater than the fitness of both homozygotes
Term
Heterozygote Superiority
Definition
the condition in which a heterozygous genotype has greater fitness than either of the homozygotes
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