Evolution Test 2

Front 1

phylogeny

Back 1

evolutionary history of a group

Front 2

phylogenetic tree

Back 2

A diagram of the relationships of ancestry and descent among a group of species or populations

Front 3

synapomorphy

Back 3

shared, derived character

Front 4

cladogram

Back 4

evolutionary tree reflecting the results of a cladistic analysis

Front 5

convergent evolution

Back 5

similarity between species that is caused by a similar, but evolutionarily independent, response to a common environmental problem

Front 6

reversal

Back 6

an event that results in the reversion of a derived trait to the ancestral form

Front 7

homoplasy

Back 7

similarity in the characters found in different species that is due to convergent evolution, parallelism, or reversal -- not common descent

Front 8

parsimony

Back 8

a criterion for selecting among alternative patterns or explanations based on minimizing the total amount of change or complexity

Front 9

maximum likelihood

Back 9

a method for choosing a preferred tree among many possible trees

Front 10

Bayesian Markov Chain Monte Carlo

Back 10

approach to phylogeny inference based on computing the probability that a particular tree is correct, given a specific model of evolution for the characters being analyzed and the data observed

Front 11

bootstrapping

Back 11

technique for estimating the strength of the evidence that a particular node is a tree exists; values range from 0-100% with higher values indicating stronger support

Front 12

polytomy

Back 12

a node, or branch point, on a phylogeny with more than two descendent lineages emerging

Front 13

systematics

Back 13

a scientific field devoted to the classification of organisms

Front 14

cladistic

Back 14

classification scheme based on the historical sequence of divergence events (phylogeny); used to identify a method of inferring phylogenies based on the presence of shared derived characters (synapomorphies)

Front 15

monophyletic groups

Back 15

set of species descended from a common ancestor

Front 16

paraphyletic groups

Back 16

set of species that includes a common ancestor and some, but not all, of its descendents

Front 17

molecular clock

Back 17

hypothesis that base substitutions accumulate in populations in a clock-like fashion, that is, a linear function of time

Front 18

phylogeography

Back 18

use of evolutionary trees in answering questions about the geographic distribution of organisms

Front 19

coevolution

Back 19

that which occurs when interactions between species over time lead to reciprocal adaptations

Front 20

complementary base pairs

Back 20

Nucleotides that match up and form hydrogen bonds on opposite strands of a DNA molecule or DNA-RNA complex; CG and AT

Front 21

point mutation

Back 21

alteration of a single base in a DNA sequence

Front 22

transition

Back 22

a mutation that substitutes a purine for a purine or a pyrimidine for a pyrimidine

Front 23

transversion

Back 23

mutation that substitutes a purine for a pyrimidine, or a pyrimidine for a purine

Front 24

replacement (nonsynonymous) substitutions

Back 24

DNA substitution that changes the amino acid or RNA sequence specified by a gene

Front 25

silent site (synonymous) substitutions

Back 25

DNA substitution that does not change the amino acid or RNA sequence specified by a gene

Front 26

loss-of-function mutations

Back 26

mutation that incapacitates a gene so that no function product is produced

Front 27

indels

Back 27

type of mutation based on the insertion or deletion of one or more DNA bases

Front 28

selection coefficient

Back 28

variable used in population genetics to represent the difference in fitness between one genotype and another

Front 29

neutral mutation

Back 29

mutation that has no effect on the fitness of the bearer

Front 30

Gene duplications

Back 30

generation of an extra copy of a locus, usually via unequal crossing over

Front 31

Unequal cross-over

Back 31

a crossing-over event between mispaired DNA strands that results in the duplication of sequences in some daughter strands and deletions in others

Front 32

pseudogenes

Back 32

DNA sequences that are homologous to functioning genes, but are not transcribed

Front 33

paralogous

Back 33

duplicated genes found in the same genome; describes the relationship among members of the same gene family; type of gene homology

Front 34

orthologous

Back 34

Genes that diverged after a speciation event; describes the relationship among homologous genes found in different species

Front 35

linkage

Back 35

tendency for alleles at different loci on a chromosome to be inherited together

Front 36

polymorphic

Back 36

describes a population, locus, or trait for which there is more than one phenotype or allele

Front 37

cline

Back 37

systematic change along a geographic transect in the frequency of a genotype or phenotype

Front 38

polyploid

Back 38

having more than two haploid sets of chromosomes

Front 39

Population Genetics

Back 39

brand of evolutionary biology responsible for investigating processes that cause changes in allele and genotype frequencies in populations

Front 40

Population

Back 40

group of interbreeding individuals and their offspring

Front 41

Gene Pool

Back 41

set of all copies of all alleles in a population that could potentially be contributed by the members of one generation to the members of the next generation

Front 42

Genetic Drift

Back 42

change in the frequencies of alleles in a population resulting from sampling error in drawing gametes from the gene pool to make zygotes and from chance variation in the survival or reproductive success

Front 43

Hardy-Weinberg Equilibrium

Back 43

situation in which allele and genotype frequencies in an ideal population do not change from one generation to the next

Front 44

Five Principles of Hardy-Weinberg

Back 44

1. No Selection
2. No Mutation
3. No Migration
4. No Genetic Drift
5. Random Mating

Front 45

Selection

Back 45

Natural selection - a difference between the survival or fecundity of individuals with certain phenotypes compared with individuals with other phenotypes

Front 46

Heterozygote Superiority (Overdominance)

Back 46

Situation in which heterozygotes at a particular locus tend to have higher fitness than homozygotes

Front 47

Underdominance

Back 47

Situation in which heterozygotes at a particular locus tend to have lower fitness than homozygotes

Front 48

Frequency-Dependent Selection

Back 48

Occurs when an individuals fitness depends on the frequency of its phenotype in the population

Front 49

Mutation-Selection Balance

Back 49

An equilibrium in the frequency of an allele that occurs because new copies of the allele are created by mutation as exactly the same rate that old copies of the allele are eliminated by natural selection

Front 50

Average Excess

Back 50

the average excess for allele a is the difference between the mean fitness of individuals carrying allele a and the mean fitness of the entire population; if positive, the allele will rise in frequency