Speciation

Question 1

What happens to allele frequencies when gene flow ends?

Answer 1

They diverge causing populations begin to evolve independently

Question 2

Process of speciation

Answer 2

When mutation, selection, and genetic drift cause isolated populations to diverge sufficiently enough to create a distinct species

Question 3

species

Answer 3

A distinct, identifiable group of populations that is thought to be evolutionarily independent of other populations and whose members can interbreed. Generally distinct from other species in appearance, behavior, habitat, ecology, genetic characteristics, etc.

Question 4

What are the criteria for identifying species

Answer 4

1) the biological species concept
2) the morphospecies concept
3) the phylogenic species concept

Question 5

biological species concept

Answer 5

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 produce viable, fertile hybrid offspring with members of other species.

Question 6

prezygotic isolation

Answer 6

prevents individuals of different species mating

Question 7

postzygotic isolation

Answer 7

offspring of matings between members of different species do not survive or reproduce.

Question 8

What are the limitations of the biological species concept?

Answer 8

Cannot be evaluated in fossil records, difficult to apply when two closely related populations overlap with each other geographically

Question 9

morphospecies concept

Answer 9

distinguishing features are most likely to arise if populations are independent and isolated from gene flow.

Question 10

cryptic species

Answer 10

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

Question 11

limitations of morphospecies concept

Answer 11

connot identify cryptic species and morphological features used to distinguish species are subjective

Question 12

phylogenic species concept

Answer 12

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

Question 13

monophyletic group

Answer 13

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

Question 14

Disadvantages of phylogenetic species concept?

Answer 14

Carefully estimated phylogenies are available only for a tiny subset of populations on the tree of life.

Question 15

What species concepts are used today?

Answer 15

All three

Question 16

How does genetic isolation occur?

Answer 16

Physical seperation

Question 17

vicariance

Answer 17

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

Question 18

allopatric speciation

Answer 18

Speciation that occurs from physical isolation either from dispersal or vicariance

Question 19

biogeography

Answer 19

The study of how species and populations are distributed geographically.

Question 20

sister species

Answer 20

Closely related species, which occupy adjacent branches in a phylogenetic tree.

Question 21

sympatry

Answer 21

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

Question 22

sympatric speciation

Answer 22

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

Question 23

How are sympatric populations isolated to stop gene flow?

Answer 23

different preferred habitat

Question 24

Are tetraploid and diploid populations common?

Answer 24

No, they rarely produce fertile offspring

Question 25

Autopolyploid

Answer 25

The state of having more than two full sets of chromosomes (polyploidy) due to a mutation that doubled the chromosome number.

Question 26

Allopolyploid

Answer 26

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

Question 27

How are polyploids evolutionarily independent?

Answer 27

They can only breed with others of their own ploidy.

Question 28

Why is polyploidy common in plants?

Answer 28

• In plants somatic cells that have undergone many rounds of mitosis can undergo meiosis and produce gametes. If error occurs in mitosis results in more chromosomes in meiosis.
• self-fertilization
• hybridization

Question 29

What are the key features of speciation by polyploidy?

Answer 29

Fast, sympatic and common

Question 30

reinforcement

Answer 30

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

Question 31

Why would hybrid offspring have lower fitness than their parents?

Answer 31

Both parents are well adapted to different habitats. Hybrids are not well adapted to either

Question 32

hybrid zone

Answer 32

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

Question 33

What are the possible outcomes of secondary contact of two populations?

Answer 33

Fusion of populations, reinforcement of divergence, founding of stable hybrid zone, extinction of one population or the creation of a new species.