Evolutionary Genetics

Question 1

Anagenesis

Answer 1

• Evolution taking place within a single lineage.

Question 2

Species

Answer 2

• Term applied to different kinds or types of living organisms.

Question 3

Biological Species Concept

Answer 3

• Definition of a species as a group of organisms whose members are capable of interbreeding with one another but are reproductively isolated from the members of other species. Because different species do not exchange genes, each species evolves independently. Not all biologists adhere to this concept.

Question 4

Reproductive Isolating Mechanism

Answer 4

• Any biological factor or mechanism that prevents gene exchange.

Question 5

Evolution

Answer 5

• Genetic change that takes place in a group of organisms.

Question 6

Cladogenesis

Answer 6

• Evolution in which one lineage is split into two.

Question 7

Speciation

Answer 7

• Process by which new species arise.

Question 8

Phylogeny

Answer 8

• Evolutionary relationships among a group of organisms.

Question 9

Phylogenetic Tree

Answer 9

• Graphical representation of the evolutionary relationships among different organisms.

Question 10

Prezygotic Isolation

Answer 10

• Reproductive isolating mechanism that prevents gametes from two different species from fusing and forming a hybrid zygote.

Question 11

Postzygotic Isolation

Answer 11

• Reproductive isolating mechanism that operates after gametes from two different species have fused to form a zygote, either because the resulting hybrids are inviable or sterile or because reproduction breaks down in subsequent generations.

Question 12

Allopatric Speciation

Answer 12

• Speciation that occurs when a geographic barrier splits a population into two groups and blocks the exchange of genes between them.

Question 13

Sympatric Speciation

Answer 13

• Speciation that arises in the absence of any geographic barrier to gene flow, in which reproductive isolating mechanisms evolve within a single population.

Question 14

Synonymous Substitutions

Answer 14

– Nucleotide changes in a gene that do not alter amino acid sequences.

Question 15

Rates Of Molecular Evolution

Answer 15

• The number of nucleotide substitutions per site per year.

Question 16

Nonsynonymous Substitutions

Answer 16

• Nucleotide substitutions that cause changes to amino acid sequences.

Question 17

Branch

Answer 17

• An evolutionary connection between nodes in a phylogenetic tree representing an evolutionary connection between organisms.

Question 18

Rooted Tree

Answer 18

• Phylogenetic tree in which one node represents a common ancestor to all other organisms (nodes) on the tree. Here all the organisms depicted have a common ancestor.

Question 19

Node

Answer 19

• Point in a phylogenetic tree where branches split; represents a common ancestor.

Question 20

Molecular Clock

Answer 20

• Use of molecular differences to estimate the time of evolutionary divergence between organisms; assumes a roughly constant rate at which one neutral mutation replaces another.

Question 21

Whole - Genome Duplication

Answer 21

– An event which creates an organism with additional copies of the entire genome of a species.

Question 22

Genome Evolution

Answer 22

• Process by which a genome changes in structure (sequence) or size over time.

Question 23

Horizontal Gene Transfer

Answer 23

• Transfer of genes from one organism to another by a mechanism other than reproduction.

Question 24

Gene Duplication

Answer 24

– A type of mutation in which one or more copies of a DNA segment is produced during molecular evolution.