Chapter 13: The Origin of Species

Question 1

phylogenetic species concept

Answer 1

species are the smallest possible groups whose members descended from a common ancestor and who all possess defining or derived characteristics that distinguish them from other such groups

Question 2

biological species concept

Answer 2

species are groups of actually (or potentially) interbreeding natural populations that are reproductively isolated from other such groups

Question 3

metapopulation

Answer 3

a group of spatially separated populations of the same species that interact at some level (ex: exchange alleles)

Question 4

general lineage species concept

Answer 4

species are metapopulations of organisms that exchange alleles frequently enough that they comprise the same gene pool, and therefore, the same evolutionary lineage

Question 5

isolating barrier

Answer 5

an aspect of the environment, genetics, behavior, physiology, or ecology of a species that reduces or impedes gene flow from individuals of other species; may be geographic or reproductive

Question 6

speciation

Answer 6

the evolutionary process by which new species arise; speciation causes one evolutionary lineage to split into two or more lineages (cladogenesis)

Question 7

allopatry

Answer 7

occurs when populations are in separate, non-overlapping geographic areas (they are separated by geographic barriers to gene flow)

Question 8

sympatry

Answer 8

occurs when populations are in the same geographic area but can’t reproduce due to reasons of not being able to literally have sex or something; must be able to find a mate, successfully fertilize egg, and produce viable offspring

Question 9

reproductive isolation

Answer 9

occurs when reproductive barriers prevent or strongly limit reproduction between populations; results in few or no genes being exchanged between populations

Question 10

gametic incompatibility

Answer 10

occurs when sperm or pollen from one species fails to penetrate and fertilize the egg of another species

Question 11

prezygotic reproductive barriers

Answer 11

aspects of the genetics, behavior, physiology, or ecology of a species that prevent sperm from one species from fertilizing eggs of another species; prezygotic barriers reduce the likelihood that a zygote will form

Question 12

postzygotic reproductive barriers

Answer 12

aspects of the genetics, behavior, physiology, or ecology of a species that prevent fertilized zygotes from successfully developing and reproducing themselves

Question 13

Bateson-Dobzhansky-Muller incompatibilities

Answer 13

molecular incompatibilities that arise when the genomes of two species are combined in hybrid offspring

Question 14

reinforcement

Answer 14

the increase of reproductive isolation between populations through the selection against hybrid offspring

Question 15

isolation by distance

Answer 15

populations that live nearby are genetically more similar to each other than populations that live farther apart

Question 16

ring species

Answer 16

a connected series of populations (each of which can interbreed with its neighboring populations) that have diverged sufficiently across their ranges so that the populations at the ends of the series are too different to interbreed

Question 17

ecological speciation

Answer 17

the evolution of reproductive behaviors between populations by adaptation to different environments or ecological niches

Question 18

allopolyploidy

Answer 18

polyploidy (more than two paired chromosomes) resulting from interspecific hybridization (if polyploidy results within a species it’s called autopolyploidy)

Question 19

cryptic species

Answer 19

groups of organisms that are genetically distinct and do not interbreed, but are morphologically almost indistinguishable

Question 20

species

Answer 20

consists of all individuals that can breed together and produce fertile offspring

Question 21

vicariance

Answer 21

development of a new barrier that separates species (as in ‘a vicariance event’) ex: habitat destruction