Topic 8

Question 1

New species arise through the process of…

Answer 1

speciation.

• an ancestral species splits into two or more descendant species that are genetically different from one another, and can no longer interbreed.

Question 2

What is macroevolution?

Answer 2

broad patterns of evolutionary change above the species level.

• evolutionary changes occurring on geological time scales.

Question 3

What is the difference between microevolution and macroevolution?

Answer 3

nothing!

they are fundamentally identical processes on different time scales.

Question 4

What is a species under the Biological Species Concept (BSC)?

Answer 4

a group of actually (or potentially) interbreeding individuals that produce viable, fertile offspring and are reproductively isolated from other species.

Question 5

What are some limitations of the BSC?

Answer 5

• cannot be applied to fossils or asexual organisms
• emphasizes the absence of gene flow

Question 6

What is the morphological species concept?

Answer 6

defines a species by structural features

• applies to sexual and asexual species

Question 7

What is the ecological species concept?

Answer 7

defines a species as a set of organisms adapted to a particular set of resources called a niche, in the environment

• applies to sexual and asexual species.

Question 8

What is the phylogenetic species concept?

Answer 8

defines a species as the smallest group of individuals on a phylogenetic tree.

• applies to sexual and asexual species.

Question 9

BSC emphasizes…

Answer 9

reproductive isolation.

Question 10

What is reproductive isolation caused by?

Answer 10

caused by biological factors (barriers) that impede two species from interbreeding and producing viable, fertile offspring (hybrids)

Question 11

What are hybrids?

Answer 11

offspring of crosses between different species

Question 12

what are prezygotic barriers?

Answer 12

block fertilization from occurring.

Question 13

Prezygotic Reproductive Barriers

What is habitat isolation?

Answer 13

when two species encounter each other rarely, or not at all because they occupy different habitats

• not isolated by physical barriers

Question 14

Prezygotic reproductive barriers

What is temporal isolation?

Answer 14

A species that breed at different times of the day or different seasons and cannot mix their gametes.

• occupy the same habitat

Question 15

Prezygotic reproductive barriers

What is behavioral isolation?

Answer 15

courtship rituals and other behaviors unique to a species are effective barriers

Question 16

Prezygotic reproductive barriers

What is mechanical isolation?

Answer 16

morphological differences can prevent successful mating

(anatomically incompatible)

Question 17

Prezygotic reproductive barriers

what is gametic isolation?

Answer 17

gametes (ex: sperm) of one species may not be able to fertilize the eggs of another species

Question 18

What are postzygotic barriers?

Answer 18

prevent a hybrid zygote from developing into a viable, fertile adult

Question 19

Postzygotic reproductive barriers

what is reduced hybrid viability?

Answer 19

genes of the different parent species may interact to impair the hybrid’s development or survival

• often results in zygote death.

Question 20

postzygotic reproductive barriers

what is reduced hybrid fertility?

Answer 20

even if the hybrids are vigorous, they may be sterile.

Question 21

Postzygotic reproductive barriers

what is hybrid breakdown?

Answer 21

some first generation hybrids are vigorous and fertile, but when these hybrids mate with one another, or with either parent species, offspring of subsequent generations are feeble and sterile.

Question 22

What is allopatric speciation?

Answer 22

The evolution of a new species following the geographic isolation of two or more subpopulations of an ancestral species.

• separated subpopulations may evolve independently through natural selection, mutation, and genetic drift

Question 23

What is sympatric speciation?

Answer 23

the evolution of a new species from an ancestral species while both continue to inhabit the same geographic region

• speciation without geographic separation
• when individuals in a sub group of the population stop gene flow with individuals of the larger population, they may eventually become a new species

Question 24

What is polyploid speciation?

Answer 24

occurs when changes in the number of chromosome sets (polyploidy) create genetically distinct descendants that are reproductively isolated from parental forms.

Question 25

What is hybrid speciation?

Answer 25

occurs when interbreeding between two related species creates genetically distinct descendants that are reproductively isolated from the parent species.

Question 26

What are polyploids?

Answer 26

have a different number of chromosome sets than their parental forms.

• polyploids arise from allopolyploids (hybrid speciation)

Question 27

What is an allopolyploid?

Answer 27

a species with multiple sets of chromosomes derived from the hybridization of different species.

• an individual with more than two chromosome sets, derived from one species.