27: Speciation

Question 1

Speciation

Answer 1

The evolution of two or more distinct species from a single ancestral species.

Question 2

species

Answer 2

An evolutionarily independent population or group of populations. Generally distinct from other species in appearance, behavior, habitat, ecology, genetic characteristics, and so on.

Question 3

biological species concept

Answer 3

The definition of a species as a population or group of populations that are reproductively isolated from other groups. Members of a species have the potential to interbreed in nature to produce viable, fertile offspring but cannot interbreed successfully with members of other species.

Question 4

prezygotic isolation

Answer 4

Reproductive isolation resulting from any one of several mechanisms that prevent individuals of two different species from mating.

Question 5

postzygotic isolation

Answer 5

Reproductive isolation resulting from mechanisms that operate after mating of individuals of two different species occurs. The most common mechanisms are the death of hybrid embryos or reduced fitness of hybrids.

Question 6

morphospecies concept

Answer 6

The definition of a species as a population or group of populations that have measurably different anatomical features from other groups. Also called morphological species concept.

Question 7

polymorphic species

Answer 7

A species that has two or more distant phenotypes in the same interbreeding population at the same time.

Question 8

cryptic species

Answer 8

A species that cannot be distinguished from similar species by easily identifiable morphological traits.

Question 9

phylogenetic species concept

Answer 9

The definition of a species as the smallest monophyletic group in a phylogenetic tree.

Question 10

monophyletic group

Answer 10

An evolutionary unit that includes an ancestral population and all of its descendants but no others. Also called a clade or lineage.

Question 11

synapomorphy

Answer 11

A shared, derived trait found in two or more taxa that is present in their most recent common ancestor but is missing in more distant ancestors. Useful for inferring evolutionary relationships.

Question 12

subspecies

Answer 12

A population that has distinctive traits and some genetic differences relative to other populations of the same species but that is not distinct enough to be classified as a separate species.

Question 13

allopatry

Answer 13

Condition in which two or more populations live in different geographic areas.

Question 14

allopatric speciation

Answer 14

Speciation that occurs when populations of the same species become geographically isolated, often due to dispersal or vicariance.

Question 15

vicariance

Answer 15

The physical splitting of a population into smaller, isolated populations by a geographic barrier.

Question 16

biogeography

Answer 16

The study of how species and populations are distributed geographically.

Question 17

sister species

Answer 17

Closely related species that occupy adjacent branches in a phylogenetic tree.

Question 18

sympatry

Answer 18

Condition in which two or more populations live in the same geography area, or close enough to permit interbreeding.

Question 19

sympatric speciation

Answer 19

The divergence of populations living within the same geographic area into different species as the result of their genetic (not physical) isolation.

Question 20

niche

Answer 20

The range or resources that a species can use and the range of conditions that it can tolerate. More broadly, the role that species plays in its ecosystem.

Question 21

polyploidy

Answer 21

(adjective: polyploid) The state of having more than two full sets of chromosomes, either from the same species (autopolyploidy) or from different species (allopolyploidy).

Question 22

autopolyploidy

Answer 22

(adjective: autopolyploid) The state of having more than two full sets of chromosomes (polyploidy) due to a mutation that doubled the chromosome number. All the chromosomes come from the same species.

Question 23

allopolyploidy

Answer 23

(adjective: allopolyploid) The state of having more than two full sets of chromosomes (polyploidy) due to hybridization between different species.

Question 24

reinforcement

Answer 24

In evolutionary biology, the natural selection for traits that prevent interbreeding between recently diverged species.

Question 25

hybrid zone

Answer 25

A geographic area where interbreeding occurs between two species, sometimes producing fertile hybrid offspring.