Biodiversity Patterns, Crisis, and Extinction Rates

All flashcards

What does biodiversity commonly describe?

The number and kinds of species and their relative abundance in a particular location or across the planet.

What is adaptive radiation?

A relatively rapid branching of an ancestral lineage into multiple species, often as populations adapt to different habitats, resources, or ecological niches.

How did Lake Victoria cichlids illustrate niche specialization?

Different cichlid species used different habitats and foods, including plankton, algae on rocks, insect larvae, and the eggs of other cichlids.

What factors contributed to the loss of Lake Victoria cichlids?

Predation by introduced Nile perch, declining water quality associated with agriculture and land clearing, and increased fishing pressure all contributed.

What are three major human drivers of contemporary biodiversity loss?

Habitat destruction, the introduction of exotic species, and over-harvesting.

Quiz questions

1. Which combination names the three commonly distinguished levels of biodiversity?Answer: Genetic variation, species diversity, and ecosystem diversity.
2. What does it mean for a species to be endemic?Answer: It occurs naturally in only one geographic location.
3. What were the original criteria for identifying a biodiversity hotspot?Answer: At least 1,500 endemic plant species and loss or disturbance of at least 70% of its area.
4. What characterizes a mass extinction in the fossil record?Answer: A sharp rise in extinction rates with a very large fraction of species disappearing over a relatively short geological interval.
5. Which mass extinction was the largest known, and what is its leading proposed cause?Answer: The end-Permian extinction, associated with extensive volcanism.