Chapter 24

Question 1

what is reproductive isolation?

Answer 1

reproductive isolation is the existence of biological barriers that impede two species from producing viable, fertile hybrids

Question 2

what are the two types of barriers?

Answer 2

prezygotic and postzygotic

Question 3

what do prezygotic barriers do?

Answer 3

prezygotic barriers impede mating or hinder fertilization if mating does occur

Question 4

examples of prezygotic barriers

Answer 4

• habitat isolation: two species don’t encounter each other because of different habitats
• temporal isolation: species breed at different times, so gametes cannot mix
• behavioral isolation: courtship rituals and other behaviors unique to a species are effective barriers
• mechanical isolation: morphological differences, they dont fit together
• gametic isolation: sperm may not be able to fertilize eggs

Question 5

what do post-zygotic barriers

Answer 5

post-zygotic barriers prevent the hybrid zygote from developing into a viable, fertile adult

Question 6

what are examples of postzygotic barriers?

Answer 6

• reduced hybrid viability: genes of the different parent species may interact and impair hybrid’s development
• reduced hybrid fertility: even if hybrids are vigorous, they may be sterile (mules cant reproduce)
• hybrid breakdown: some hybrids are fertile, but when they mate, offspring of next generation are feeble or sterile

Question 7

what are the two ways speciation can occur?

Answer 7

speciation can occur in allopatric speciation or sympatric speciation

Question 8

what happens in allopatric speciation?

Answer 8

in allopatric speciation, gene flow is interrupted or reduced when a population is divided into geographically isolated subpopulations, they may undergo evolutionary change during separation

Question 9

what happens in sympatric speciation?

Answer 9

in sympatric speciation, speciation takes place in geographically overlapping populations

Question 10

what determines if allopatric speciation occurred?

Answer 10

reproductive isolation must have been established

Question 11

what determines if members are of the same biological species?

Answer 11

if they are reproductively compatible; cannot interbreed with other populations

Question 12

what is polyploidy?

Answer 12

polyploidy is presence of extra sets of chromosomes due to accidents during cell division, it is a common way for plants to become a different species

Question 13

is polyploidy allopatric or sympatric?

Answer 13

polyploidy is sympatric

Question 14

what happens in allopatric vs sympatric?

Answer 14

allopatric is formation of new species from being separated
sympatric is a reproductive barrier that isolates population without being separated