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Biol 121- 2010.04.12- Ecology- Biodiversity and Conservation (Ch. 55).docx

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University of British Columbia
BIOL 121

Biol 121 225 Freeman, Ch. 55 Apr 12, 10 Ecology: Biodiversity and Conservation Measures of biodiversity (2) 1. Species richness -number of species in a given area 2. Diversity -number of species and relative abundance Scales of biodiversity – Ecological 1. Genetic diversity scale (3) -total genetic information contained within all individuals of a species, measured as the number and relative frequency of all alleles present in a species 2. Species diversity -based on the variety of species on Earth – can measure number and relative fq of species in a region 3. Ecosystem diversity -variety of biotic communities in a region along with abiotic components, such as soil, water, and nutrients Space and time (2) 1. alpha: biodiversity ‘here’ or within one community 2. Beta: biodiversity ‘here’ vs. ‘there’ (or ‘now’ vs. ‘later’) e.g. of beta biodiversity in forest Year 0: clear-cut the area diversity changes Year 3: there are many saplings and flowers Year 100: Canopy has closed in and therefore flowers and shorter plants not exposed to sun as much and die off Year 300+: old growth – old trees fall, allowing more sunlight to hit the ground and new species arise -out of these years, year 3 will have the highest alpha biodiversity Distribution of biodiversity -44% of plants and 35% of all the species on Earth are in an area that is 1.4% the size of the Earth Values of biodiversity (3) 1. Economic – certain species can be used for medicine, food, etc 2. Ecosystem service – what nature does for humans – water filtration, pollination, carbon storage (naturally) 3. Intrinsic – life has value because it exists? e.g. yew trees -people can get some substance from yew trees with which a cancer fighting agent can be synthesized -as a result, many yew trees were cut down and stuff and used (economic use) but then 90% of the yew trees were wiped out in the area from which it was taken (somewhere in Canada) Functions of diversity (2) 1. Resistance – is the ability to maintain normal function during disturbance 2. Resilience – is the ability to recover normal function following a disturbance Hypotheses for the function of 1. Diversity-stability – as #spp increases, (rate of) ecosystem process diversity increases 2. Rivet 3. Redundancy – as number of spp increases, (rate of) ecosystem process increases but then reaches a plateau 4. No effect – number of species will be random with ecosystem process Loss of biodiversity 1. Exploitation (e.g. people kill off things for food or for fun or whatever) 2. Habitat loss a. removal – “no structure” – e.g. clear cutting, road building, etc 1 Biol 121 225 Freeman, Ch. 55 Apr 12, 10 b. Degradation – structure or food in poor condition (e.g. polluting a stream) c. Resource loss – structure intact, but for example no more food d. Invasive species – structure changes, more competition e. Climate change – distribution of habitat changes with climate Habitat removal versus -habitat removal means that structures are removed (e.g. clear cutting) fragmentation -it is destroying natural areas outright (taking away a large square area of land) -fragmentation on the other hand means that human activities fragment large, contiguous areas of natural habitats into small, isolated fragments -think of a large area of trees and building streets so that a grid-like shape of roads forms – now the populations are isolated in each ‘block’  fragments -this can reduce habitats to a size too small to support some species (especially true for keystone predators like mountain lions, etc that need vast natural spaces to feed, find mates, and reproduce successfully) -also, fragmentation reduces the ability of individuals to disperse from one habitat to another (isolated populations are much more likely to be wiped
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