Biology Unit 2, Chapter 24

Front 1

What is speciation?

Back 1

The process by which one species splits into two or more species.

Front 2

What is microevolution?

Back 2

Changes over time in allele frequencies in a population.

Front 3

What is macroevolution?

Back 3

The broad pattern of evolution over long time spans.

Front 4

What is biological species concept?

Back 4

A species is a group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring-but not produce viable, fertile offspring with members of other such groups.

Front 5

What is reproductive isolation?

Back 5

The existence of biological factors (barriers) that impede members of two species from producing viable, fertile offspring.

Front 6

What are hybrids?

Back 6

Offspring that result from an interspecific mating.

Front 7

Prezygotic Barriers

Back 7

Before the zygote that block fertilization from occurring.

Front 8

Postzygotic Barriers

Back 8

After the zygote that may contribute to reproductive isolation after the hybrid zygote is formed.

Front 9

What is Habitat Isolation?

Back 9

Two species that occupy different habitats within the same area may encounter each other rarely, if at all, even though they are not isolated by obvious physical barriers.

Front 10

What is Temporal Isolation?

Back 10

Species that breed during different times of the day, different seasons, or different years cannot mix their gametes.

Front 11

What is Behavioral Isolation?
(Prezygotic)

Back 11

Courtship rituals that attract mates and other behaviors unique to a species are effective reproductive barriers, even between closely related species. Such behavioral rituals enable mate recognition-a way to identify potential mates of the same species.

Front 12

What is Mechanical Isolation?
(Prezygotic)

Back 12

Mating is attempted, but morphological differences prevent its successful completion.

Front 13

What is Gametic Isolation?
(Prezygotic)

Back 13

Sperm of one species may not be able to fertilize the eggs of another species. For instance, sperm may not be able to survive in the reproductive tract of females of the other species, or biochemical mechanisms may prevent the sperm from penetrating the membrane surrounding the other species' eggs.

Front 14

What is Reduced Hybrid Viability?
(Postzygotic)

Back 14

The genes of different parent species may interact in ways that impair the hybrid's development or survival in its environment.

Front 15

What is Reduced Hybrid Fertility?
(Postzygotic)

Back 15

Even if hybrids are vigorous, they may be sterile. If the chromosomes of the two parent species differ in number or structure, meiosis in the hybrids may fail to produce normal gametes. Since the infertile hybrids cannot produce offspring when they mate with either parent species, genes cannot flow freely between the species.

Front 16

What is Hybrid Breakdown?
(Postzygotic)

Back 16

Some first-generation hybrids are viable and fertile, but when they mate with one another or with either parent species, offspring of the next generation are feeble or sterile.

Front 17

What does Biological Species Concept rely on?

Back 17

Species are designated by the absence of gene flow.

Front 18

What is Morphological Species Concept?

Back 18

It characterizes a species by body shape and other structural features.

Front 19

What is Ecological Species Concept?

Back 19

It views species in terms of its ecological niche, the sum of how members of the species interact with the nonliving and living parts of their environment.

Front 20

What is Phylogenetic Species Concept?

Back 20

It defines a species as the smallest group of individuals that share a common ancestor, forming one branch on the tree of life.

Front 21

What happens in Allopatric Speciation?

Back 21

Gene flow is interrupted when a population is divided into geographically isolated subpopulations.

Front 22

What happens in Sympatric Speciation?

Back 22

Speciation occurs in populations that live in the same geographic area.

Front 23

What is Polyploidy?

Back 23

A condition where a species may originate from an accident during cell division that results in an extra set of chromosomes.

Front 24

What is Autopolyploid?

Back 24

Is an individual that has more than two chromosome sets that are all derived from a single species.

Front 25

What is Allopolyploid?

Back 25

They are fertile in mating with each other but cannot interbreed with either parent species; thus, they represent a new biological species.

Front 26

What is a Hybrid Zone?

Back 26

A region in which members of different species meet and mate, producing at least some offspring of mixed ancestry.

Front 27

What is Punctuated Equilibria?

Back 27

Phrase used to describe these periods of apparent stasis punctuated by sudden change in fossils.