KA7/8 Components + Threats to Biodiversity

Question 1

what is genetic diversity?

Answer 1

the number and frequency of alleles in a population

Question 2

what is ecosystem diversity?

Answer 2

variety of distinct ecosystems within a defined area

Question 3

what is species diversity?

Answer 3

the number of species (species richness) and the proportion of each species (relative abundance) in an ecosystem

Question 4

describe overexploitation

Answer 4

overexploitation involves resources being consumed at a rate greater than they can be replaced. if overexploitation is halted soon enough, populations may be able to recover

Question 5

describe the bottleneck effect

Answer 5

if populations reduce drastically (e.g. due to a natural disaster or overexploitation) and only a small population remains it may have lost the genetic diversity required to be able to make evolutionary responses to environmental change. small populations with low genetic diversity tend to inbreed which leads to poor reproductive rates, greater susceptibility to disease, and low survival rates.

Question 6

define habitat fragmentation

Answer 6

habitat fragmentation is when a habitat is broken up into smaller fragments

Question 7

describe the effect of habitat fragmentation on ecosystems

Answer 7

habitat fragments typically support lower species richness than larger areas of the same habitat. habitat fragments suffer from degradation at their edges which can further reduce their size. edges of fragments can be invaded by edge species adapted to habitat edges at the expense of interior species.

Question 8

how can habitat corridors moderate the effects of fragmentation

Answer 8

isolated habitat fragments can be linked by habitat corridors. these allow species to move between species to mate, feed, and recolonise

Question 9

what are introduced species?

Answer 9

introduced species are all non-native species which have been intentionally or accidentally moved by humans to new geographic locations. they can be naturalised or invasive

Question 10

what are naturalised species?

Answer 10

introduced species which have become established within wild communities

Question 11

what are invasive species?

Answer 11

introduced species which have spread rapidly, eliminating indigenous species by out-competing them, hybridising with them, or preying on them, thus reducing species diversity. invasive species may be free of predators, parasites, or pathogens which would normally limit them in their natural habitat