Biodiversity Flashcards
What are the measurable components of biodiversity?
genetic diversity
species diversity
ecosystem diversity
What is genetic diversity?
A measure of genetic differences within and between individuals, populations and species
It is the number and frequency of all the alleles within a population
What may happen if one population of a species dies out?
The species may have lost some of its genetic diversity and this may limit its ability to adapt to changing conditions
What does species diversity comprise of?
The number of different species in an ecosystem (species richness)
The proportion of each species in the ecosystem (relative abundance)
What does it mean if a community has a dominating species?
It has a lower species diversity than one with the same species richness but no particularly dominating species
What does ecosystem diversity refer to?
The number of distinct ecosystems within a defined area
What has led to overexploitation of some species?
A growing human population
eg overfishing fish to the point where it is no longer sustainable
Can populations still recover after overexploitation?
They can be reduced to a low level but may still recover
What is a population bottleneck/genetic bottleneck?
An evolutionary even in which a significant percentage of a population or species is killed or otherwise prevented from reproducing
What is the impact of a population bottleneck?
Small populations may lose genetic variation necessary to enable evolutionary response to environmental change
In small populations, this loss of genetic diversity can be critical for many species, as inbreeding can result in poor reproductive rates
Can species have a naturally low genetic diversity in their population and yet remain viable?
yes
What is habitat fragmentation and what can lead to it
It is the break up of an organism’s preferred habitat
Human activities can lead to it
Examples of habitat fragmentation
-clearing forests for agriculture
-clearing forest/agriculture land for housing/industry
-building dams and flooding surrounding land
-building roads
Impact of habitat fragmentation
degradation of the edges of habitat fragments results in increased competition between species as the fragment becomes smaller
This may result in a decrease in biodiversity as species may be lost
What do more isolated fragments and smaller fragments exhibit?
a lower species diversity
What happens as fragmentation increases?
Species diversity decreases
What is one possible way of reducing the impact of widespread habitat fragmentation ?
by linking isolated fragments with habitat corridors
What is an advantage of habitat corridors and what does this lead to?
They allow movement of animals between fragments, increasing access to food and choice of mates
This may lead to recolonisation of small fragments after local extinctions
What is an introduced (non-native) species?
One that humans have moved either intentionally or accidentally to new geographic locations
eg grey squirrels introduced to europe
What is a naturalised species?
Species that become established within wild communities
It will be able to flourish in the new environment without human impact
What is an invasive species?
They are naturalised species that spread rapidly and eliminate native species, therefore reducing species diversity
What may invasive species be free of?
The predators, parasites, pathogens and competitors that limit their population in their native habitat
What may invasive species do to native species?
Prey on them
Outcompete them for resources
or hybridise with them
