ch 17

Question 1

biological species concept (BSC)

Answer 1

population or group of populations within which genes are actually or potentially exchanged by interbreeding, and which are reproductively isolated from other such groups

Question 2

coadapted

Answer 2

alleles at different loci within the same population have presumably been selected to form harmonious combinations

Question 3

conspecific

Answer 3

belonging to same species

Question 4

Dobzhandsky-Muller (DM) imcopatibility

Answer 4

reduction in the fitness of a hybrid because of interaction between certain alleles in one parent population with specific alleles at other loci in the other parent population

Question 5

ecological isolation

Answer 5

mechanism that reduce the opportunities for closely related sympatric species to meet and mate

Question 6

Haldane’s rule

Answer 6

generaliztion that when only one sex manifests sterility or inviability in hybrids between species, it is the heterogametic sex ( with two different sex chromosomes) that does so

Question 7

hybrid zone (primary, secondary)

Answer 7

region in which genetically distinct populations come into contact and produce at least some offspring of mixed ancestry

Question 8

hybridization

Answer 8

production of offspring by interbreeding between members of genetically distinct populaiton

Question 9

introgression

Answer 9

movement of genes from one species or population into another by hybridization and backcrossing; carries the implication that some genes in a genome undergo such movement, but others do not

Question 10

isolating barriers

Answer 10

genetically determined difference between populations that restricts or prevents gene flow between them. The term does not include spatial segregation by extrinsic geographic or topographic barriers

Question 11

lineage sorting

Answer 11

process by which each of several descendant species, carrying several gene lineages inherited from a common ancestral species, acquires a single gene lineage; hence, the derivation of a monophyletic gene tree, in each species, from the paraphyletic gene tree inherited from their common ancestor

Question 12

phylogenetic species concept (PSC)

Answer 12

species conceived as groups of populations that are distinguishable form other such groups

Question 13

postzygotic barriers

Answer 13

occurring after union of the nuclei or uniting gametes; usually refers to inviability or sterility that confers reproductive isolation

Question 14

premating barriers

Answer 14

occurring before union of nuclei of uniting gametes; usually refers to events in the reproductive isolation, including those that occur before mating

Question 15

prezygotic barriers

Answer 15

occurring before union of nuclei of uniting gametes; usually refers to events in the reproductive isolation, including those that occur before mating

Question 16

reproductive isolation

Answer 16

reduction of gene exchange between populations by any several possible factors, usually those arising form biological differences between population

Question 17

secondary contact

Answer 17

contact and potential interbreeding between formerly allopatric populations, owing to range expansion

Question 18

semispecies

Answer 18

one of several groups of population that are partially but not entirely isolated from one another by biological factors

Question 19

sexual isolation

Answer 19

reduction of gene exchange between populations because of aversion to mating with members of the other population

Question 20

sibling species

Answer 20

species that are difficult or impossible to distinguish by morphological characters, but may be discerned by differences in ecology, behavior, chromosomes, genetic markers, or other such features

Question 21

sister species

Answer 21

two species with an immediate common ancestor