c.4- conservation and biodiversity Flashcards
define an indicator species
an organism used to assess a specific environmental condition
why are certain species good indicators?
because they only occur when specific environmental conditions are present
how can we calculate the value of a biotic index?
by using relative numbers/frequencies of indicator species
state the equation for biotic index
check
A high biotic index indicates
the presence of many pollution-sensitive organisms, denoting an unpolluted environment
A low biotic index indicates
a relative abundance of pollution-tolerant organisms, denoting a polluted environment
define in situ conservation
measures involving endangered species remaining in the habitat to which they are adapted
in situ conservation may require
active management of nature reserves or national parks, eg:
- controlled grazing
- removal of shrubs and trees
define ex situ conservation
measures involving removal of organisms from their natural habitat.
state a case study of the captive breeding and reintroduction of an endangered animal species
Peregrine falcon
- became endangered because of the widespread use of DDT
- conservation workers collected eggs from nests and replaced them with porcelain replicas , then incubated them
- this ensured a greater frequency of hatching
state the two components of biodiversity
richness and evenness
define richness
the number of different species present
define evenness
how close in numbers each species is
give the formula for Simpson’s reciprocal index of diversity
check
what does the Simpson’s reciprocal index of diversity do?
it quantifies biodiversity by taking richness and evenness into account
the higher the value of D, the higher the biodiversity.
—— ——- can affect species diversity
biogeographic factors
analyse the impact of island size on diversity
Biodiversity is proportionate to island size
Larger islands:
- support a greater range of habitats (and hence more available niches for species to occupy)
- sustain higher population numbers for each species (increases species evenness)
- greater productivity at each trophic level, leading to longer and more stable food chains
analyse the impact of edge effects on diversity
Edge effects occur at ecotones (where two habitats meet and there is a change near the boundary). More species exist at ecotones as species from different habitats converge leading to increased predation and competition.
However certain species may not be able to thrive under these conditions and instead must occupy more central regions.
These effects depend on the particular abiotic conditions.
