Macroevolution Topic 10

What is evolution?

A process that occurs at two scales, leading to changes in species over time.

What is a species?

A group of related organisms that maintain distinct traits in nature, forming the largest possible gene pool.

What is macroevolution?

The formation of new species that occurs as microevolutionary changes accumulate over many generations.

What are subspecies?

Groups of organisms with some different traits, but not enough to warrant classification as different species.

What is the morphological species concept?

A species concept based on unique physical characteristics of distinct organisms.

What is the ecological species concept?

A classification of species based on their unique ecological niche and its influence on the environment.

What is the biological species concept?

Defines a species based on the potential to interbreed and produce viable, fertile offspring.

What are reproductive isolation mechanisms (R.I.M.s)?

Barriers that prevent individuals from producing viable, fertile offspring.

What types of barriers are in pre-zygotic isolation?

Habitat isolation, temporal isolation, behavioral isolation, mechanical isolation, gametic isolation.

What does habitat isolation refer to?

Geographical behavior leading to habitat choices that prevent species from coming into contact.

What is hybrid viability?

A post-zygotic barrier where hybrid embryos have impaired development or survival.

What is reduced hybrid fertility?

A scenario where interspecies hybrids are viable but sterile, preventing successful reproduction.

What is hybrid breakdown?

A situation where initial hybrids are viable and fertile, but their subsequent generations lose fitness.

What are the mechanisms of microevolution?

Mutations, natural selection, nonrandom mating, genetic drift, and gene flow.

How does speciation occur?

Through the interplay of mutation, natural selection, nonrandom mating, genetic drift, and reproductive isolation.

What is gene flow?

The exchange of genetic material between populations through interbreeding.

What is sexual dimorphism?

The differences in appearance between male and female members of the same species.