SPECIATION L21

Question 1

speciation

Answer 1

• process by which 1 species splits into 2

- the appearance of a new species

Question 2

biological species concept

Answer 2

• group of populations whose members have potential to interbreed in nature and produce viable offspring
• share common gene pool
• gene flow between populations of same species
• no gene flow with different species (reproductive isolation)

Question 3

limitations of BSC

Answer 3

• extinct/fossil species
• asexual species
• viruses/microbes

Question 4

morphological species concept

Answer 4

• species distinguished by shape/structure
• applies equally well to sexual, asexual, extinct species
• disagreement over which features are most important

Question 5

ecological species concept

Answer 5

• species defined by ecological niche

- works for sexual and asexual organisms, but must be extant

Question 6

ecological niche

Answer 6

• how individuals interact with living and nonliving parts of environment

Question 7

reproductive isolation

Answer 7

• mechanisms that prevent members of different species from interbreeding and producing viable, fertile offspring
• prevents gene flow
• prevents formation of hybrids
• hybrids often have low fitness
• • selection for mechanisms to prevent hybridization

Question 8

habitat isolation - pre

Answer 8

• overlapping geographic range, but live/breed in different areas
• rarely interact, no opportunity to interact

Question 9

temporal isolation - pre

Answer 9

• overlap, but breed at different times (different times of year, season, day)

Question 10

behavioral isolation - pre

Answer 10

• species unique behaviors enable mate recognition

Question 11

mechanical isolation - pre

Answer 11

• mating attempted by sexual structure incompatible

Question 12

gametic isolation - pre

Answer 12

• molecular or chemical differences between species
• egg and sperm incompatible
• common in aquatic organisms - release gametes into water
• but sometimes fertilization occurs between 2 species

Question 13

reduced hybrid viability - post

Answer 13

• embryo dies early in development

Question 14

reduced hybrid fertility - post

Answer 14

• hybrids viable, but sterile or low fertility

- often due to problems during meiosis

Question 15

hybrid breakdown - post

Answer 15

• 1st gen hybrids viable and fertile
• hybrids can mate with each other or parent species
• subsequent offspring infertile or frail

Question 16

allopatric speciation

Answer 16

• geographic isolation – drift or selection – divergence

Question 17

migration

Answer 17

• small offshoot population – isolated from parent population

Question 18

sympatric speciation

Answer 18

• reproductive isolation without geographic isolation

Question 19

polyploidy

Answer 19

• having more than 2 sets of chromosomes
• mechanism of sympatric speciation
• reproductive isolation
• within single species or hybrids

Question 20

sexual selection

Answer 20

• selection for different traits in males and females
• mechanism of sympatric speciation
• can become a barrier to reproduction between subpopulations

Question 21

habitat differentiation

Answer 21

• subpopulation uses habitat or resources not used by rest of population
• can lead to habitat isolation
• habitat isolation – temporal isolation – post zygotic barriers