How Biological Diversity Evolves: The Origin of Species

Flashcards about Biological Diversity and the Origin of Species, covering speciation, reproductive barriers, allopatric and sympatric speciation, macroevolution, the fossil record, plate tectonics, biogeography, mass extinctions, and mechanisms of macroevolution.

What is speciation?

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

What is the biological species concept?

A group of populations whose members have the potential to interbreed with one another in nature and produce fertile offspring.

Give three ways biologists may define a species

According to measurable physical traits, solely on the basis of molecular data (a sort of bar code), or as the smallest group of individuals sharing a common ancestor.

What is a reproductive barrier?

Anything that prevents individuals of closely related species from interbreeding.

What are prezygotic barriers?

Barriers that prevent mating or fertilization between species.

What are postzygotic barriers?

Barriers that operate if interspecies mating occurs and hybrid zygotes form.

What is allopatric speciation?

Speciation in which the initial block to gene flow is a geographic barrier that physically isolates the splinter population.

What is sympatric speciation?

Speciation without geographic isolation.

What factors can reduce gene flow in sympatric populations?

Polyploidy, habitat complexity, and sexual selection.

Give examples of polyploid plants.

Oats, potatoes, bananas, strawberries, peanuts, apples, sugarcane, and wheat.

What is macroevolution?

Evolutionary change above the species level, including the impact of mass extinctions and the origin of key adaptations.

What is the fossil record?

The sequence in which fossils appear in rock strata and an archive of macroevolution.

What is radiometric dating?

A method based on the decay of radioactive isotopes used to learn the ages of rocks and fossils.

What is the theory of plate tectonics?

The continents and seafloors form a thin outer layer of solid rock, called the crust, divided into giant, irregularly shaped plates that float atop the mantle.

What is continental drift?

Movements in the mantle cause the plates to move.

What was Pangaea?

The supercontinent formed about 250 million years ago when plate movements joined all landmasses.

What is biogeography?

The study of the past and present distribution of organisms.

Name a major extinction event mentioned in the notes.

The Permian mass extinction or The Cretaceous extinction

What is the focus of evo-devo studies?

How slight changes in the flow of genetic information can become magnified into major structural differences among species.

allopatric

The type of speciation in which a new species forms by geographic isolation.

biogeography

The study of the past and present distribution of organisms.

convergent evolution

The type of evolution in which unrelated organisms evolve structures with similar functions.

macroevolution

Major biological changes evident in the fossil record.

postzygotic barriers

The type of barriers that prevent development of a zygote that is a hybrid between species.

prezygotic barriers

The type of barriers that prevent the fertilization of the eggs of different species.

sympatric

The type of speciation in which a new species forms in the same geographic region.