ch. 13: the origin of species

Question 1

Biological Species Concept

Answer 1

species are groups of potentially interbreeding populations that are reproductively isolated from other such groups
**works well for sexually reproducing animals

Question 2

Phylogenetic Species Concept

Answer 2

smallest possible group descending from a common ancestor and recognizable by unique, derived traits
*useful for systematics and focuses on phylogenetic history

Question 3

General Lineage Species Concept

Answer 3

species are meta-populations that exchange alleles frequently enough to comprise the same gene pool

Question 4

Metapopulation

Answer 4

group of spatially separated populations of the same species that interact at some level

Question 5

What are isolating barriers to reproduction?

Answer 5

1. Geographic: extrinsic properties of landscape that prevent gene flow
   ->allopatry: occurs when populations are in separate, non-overlapping geographic ares (barriers to gene flow)
   ->sympatry: occurs when population are in the same geographic area
2. Reproductive: features of organism that prevent interbreeding
   EX: mismatched morphology of reproductive organs (carabus beetles in japan)

Question 6

Prezygotic Reproductive Barriers

Answer 6

**BEFORE formation of zygote
aspects of the genetics, behavior, physiology, or ecology of a species that prevent sperm from one species from fertilizing eggs of another species
-copulatory behavioral isolation
-genetic incompatibility

Question 7

Copulatory behavioral isolation

Answer 7

mating between species results in damage to female reproductive tract and different species males copulatory courtship results in eggs NOT fertilized by deposited sperm

Question 8

Genetic incompatibility

Answer 8

sperm or pollen from one species fails to penetrate and fertilized the egg of another species

Question 9

Postzygotic Reproductive Barriers

Answer 9

**AFTER formation of zygote
-hybrids are produced but have low fitness
1. hybrid inviability
2. hybrid sterility
3. ecological inviability
4. behavioral sterility

Question 10

Bateson-Dobzhansky-Muller incompatibility

Answer 10

genetic incompatibility in hybrid offspring arising from epistatic interactions at two or more loci

Question 11

Allopatric Speciation

Answer 11

reproductive isolation evolves as a result of geographic (physical) barrier to gene flow
-reinforcement: natural selection favors prezygotic isolation mechanisms that prevent the formation of hybrids with reduced fitness
-isolation by distance: populations tend to breed with those in close proximity

Question 12

Sympatric Speciation

Answer 12

reproductive isolation evolves without geographic isolation
*requires nonrandom mating based on genetic factors

Question 13

Ecological Speciation

Answer 13

selection for different ecological traits in different niches creates reproductive barriers

Question 14

Postzygotic isolation must evolve in _____ .

Answer 14

allopatry

Question 15

What does allopatric isolation by distance cause?

Answer 15

variation across the range of species

Question 16

What does ecological speciation lead to?

Answer 16

pre and post zygotic isolation

Question 17

Allopolyploidy

Answer 17

polyploidy (more than two paired chromosomes) resulting from interspecific hybridization
**can lead to extremely rapid speciation

Question 18

The speed for speciation varies among ___.

Answer 18

taxa

Question 19

Examples of Allopolyploidy

Answer 19

mules (allodiploid) and cotton (alltetraploid)

Question 20

Horizontal gene transfer makes ____ difficult.

Answer 20

classification

Question 21

Stable Ecotype Model

Answer 21

species defined as a long-lived population of genetically related individuals that share a stable set of adaptations for the same ecological niche