chapter 16 - speciation

Question 1

define species

Answer 1

a group organisms that mate with one another

Question 2

are species concepts mutually exclusive?

Answer 2

no ma’m

Question 3

what is the morphological species concept?

Answer 3

a species is a group of organisms that look like one another (because of a common gene pool)

Question 4

what is the problem with the morphological species concept?

Answer 4

phenotypic variation because of geographic distance between a species
differences in appearance based on sex
cryptic species look identical but cannot mate with one another

Question 5

what is the lineage species concept?

Answer 5

species are terminal monophyletic branches on a phylogenetic tree
each has a history that starts at a speciation event and ends at another or at extinction

Question 6

define speciation

Answer 6

1 species splits into 2+ daughter species, which then evolve as distinct lineages

Question 7

what is the biological species concept?

Answer 7

a species is a group of interbreeding populations that are reproductively isolated from other groups

Question 8

what is the most accepted species concept?

Answer 8

biological

Question 9

define reproductive isolation

Answer 9

the inability of a species to breed successfully with related species due to geographical, behavioral, physiological, or genetic barriers or differences

Question 10

define prezygotic reproductive barriers

Answer 10

things that occur before the act of fertilization that prevent mating
ex. habitat, timing, behavior, mechanics, etc.

Question 11

define postzygotic reproductive barriers

Answer 11

an act that occurs after fertilization that prevents the development of offspring (lowers fertility)
ex. F1 progeny are inviable or sterile

Question 12

why is reproductive isolation necessary?

Answer 12

for lineages to remain distinct through evolutionary time - otherwise, the exchange of genes maintains a common gene pool

Question 13

what is the Dobzhansky-Muller model?

Answer 13

explains the evolution of reproductive isolation
new alleles arise from mutation and eventually fix to the point that they cannot reproduce with populations that have contrasting fixed genes

Question 14

what are Dobzhansky-Muller genetic incompatibilities?

Answer 14

when two reproductively isolated populations come back together and interbreed, they may produce hybrids - however, the new combo of alleles in the hybrid offspring may be incompatible and may be functionally inferior/inviable

Question 15

how does the D-M model work for chromosomal rearrangement?

Answer 15

viable offspring must not have any duplications of chromosomes - other possibilities with duplications reduce fertility

Question 16

define allopatric speciation

Answer 16

speciation that occurs when populations are separated by a physical barrier
ex. mountain, river, etc.

Question 17

what is the most dominant mode of speciation?

Answer 17

allopatric speciation

Question 18

allopatric speciation is also called:

Answer 18

geographic speciation

Question 19

define sympatric speciation

Answer 19

a separation of a gene pool without physical isolation

Question 20

sympatric speciation can occur with what kind of selection:

Answer 20

disruptive selection - certain genotypes have preference for distinct microhabitats
ex. fruit flies laid eggs only on hawthorn fruits until apples were introduced to North America - now there are 2 separate fruit fly species

Question 21

strengthening prezygotic barriers is:

Answer 21

reinforcement of reproductive isolation