Chapter 20: Speciation and Macroevolution

Macroevolution

________ concerns large- scale phenotypic changes in populations that typically warrant the placement of the populations in taxonomic groups at the species level and higher, that is, new species, genera, families, orders, classes, and even phyla, kingdoms, and domains.

Postzygotic barriers

________ are reproductive isolating mechanisms that prevent gene flow after fertilization has taken place.

Evolutionary novelties

________ may be due to changes during development, the orderly sequence of events that occurs as an organism grows and matures.

Prezygotic barriers

________ are reproductive isolating mechanisms that prevent fertilization from taking place.

phyletic gradualism

According to the ________ model, populations slowly diverge from one another by the accumulation of adaptive characteristics within a population.

Feathers

________ are an example of a preadaptation.

axolotl salamanders

Adult ________, with external gills and tail fins, are an example of paedomorphosis.

Temporal isolation

________ occurs when two species reproduce at different times of the day, season, or year.

Sympatric speciation

________ occurs in animals, such as fruit maggot flies and cichlids, but how often it occurs and under what conditions remain to be determined.

Allometric growth

________, varied rates of growth for different parts of the body, results in overall changes in the shape of an organism.

Extinction

________ is the death of a species.

Hawaiian honeycreepers

________ and silverswords both underwent adaptive radiation after their ancestors colonized the Hawaiian Islands.

Adaptive radiation

________ is the process of diversification of an ancestral species into many new species.

Speciation

________ is the evolution of a new species from an ancestral population.

Mechanical isolation

________ is due to incompatible structural differences in the reproductive organs of similar species.

Hybrid inviability

________ is the death of interspecific embryos during development.

Allopatric speciation

________ (e.g., in Death Valley pupfishes) occurs when one population becomes geographically isolated from the rest of the species and subsequently diverges.

Short periods of active speciation

________ are interspersed with long periods of stasis.

behavioral isolation

In ________ distinctive courtship behaviors prevent mating between species.

Evolutionary novelties

________ may originate from preadaptations, structures that originally fulfilled one role but changed in a way that was adaptive for a different role.

sympatric speciation

In plants ________ can result when a polyploid individual (one with more than two sets of chromosomes) is an allopolyploid hybrid derived from two species.

Sympatric speciation

________ does not require geographic isolation.