biodiversity Flashcards
(21 cards)
what is ecology?
the study of the distribution and abundance of organisms, and the interaction among these.
what is the biological hierarchy?
Cells > tissues > organs >
individual organisms >
populations > communities >
ecosystems > ecoregions >
biogeographic regions >
biosphere
what is biodiversity?
the variation of life at all levels of biological organisation
species definition
a group of organisms whose members freely interbreed
population definition
a group of organisms of the same species that occupy that live in the same area at the same time
community definition
all the populations of different species that live and interact in the same area at the same time
ecosystem definition
a community and its physical (abiotic) environment
how do we measure biodiversity?
- species (mostly)
- genetic
- ecosystems
how many living species?
2 billion
how many insects?
approx. 6.8 million, each host at least 10 unique bacterial species
alpha diversity
measured locally
how a group of organisms interact and compete with each other in the same environment (community)
number of species within a given area
beta diversity
measured between two different sites
high beta diversity = low similarity in species composition among the sites
gamma diversity
total species diversity in a landscape/region
combination of alpha and beta diversity
what’s the issue with measuring biodiversity evenness?
evenness = how equally spread
differences in abundance need considering
whats the species rank abundance curve?
describes diversity by plotting abundance against abundance/species rank
ways to consider rarity
- size of geographical range
- habitat specificity
- local population density
rare species less likely to be samples but most vulnerable to extinction
rarefaction curves = indicate the completeness of sampling
patterns of diversity
diversity not distributed equally across the globe
diversity hotspot
a biogeographic region with significant levels of biodiversity that is threatened with destruction
- must contain at least 1500 species of vascular plants found no where else on earth (endemic species)
- have lost at least 70% of primary native vegetation
how many diversity hotspots are there
36
example of diversity hotspot
Sundaland, SE Asia > 15000 endemic plant species and lost 95% of vegetation
keystone species
species that have a disproportionately large effect on its environment relative to its abundance - usually predators
e.g sea otters, they predate on burrowing crabs that accelerate marsh erosion
