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BGYC63 Nov08

Biological Sciences
Course Code
Ivana Stehlik

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for assignment: show t value, df, and p (significance of test) and CI or SE
BIOC63 Nov08
Species and Population Approach
1. Why focus on species/populations?
- species are the unit of evolution; which creates biodiversity
-so inorder to keep biodiversity, we must preserve species
- each coutnry has its own endangered species list (international)
- we are more likely to get money when it is species oriented (saving river vs saving panda)
2. Life history characteristsics of species as predictors of extinction likelihood
- extinction rate of primates vs carnivores
- the greatest predictor of the extinction of a species is its geographic range
- also for primates, it is also body mass (the greater the body size, the higher chance of it
becoming extinct)
- on the other hand, for carnivores, the longer the gestation length, the higher chance of them
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becoming extinct)
- on a different graph, just looking at song birds (we are currently losing them at the strongest
- the more the bird is picky on its habitat, the lower the population size
- and omnivores are doing better than those birds who only feed on seeds
- fresh water fish vs marine fish
- for fresh water, the distribution of size that is at risk is similar to the entire data
- body size is a very good predictor of extinction for marine fishes (large fishes are much more
hunted than thier original distribution of sizes)
- plants; how they are pollinated
- the plant species are least at risk then they depend on the wind for polonation, on the other hand
it becomes highly at risk when the plant depends on a single species for pollination
- also, the sexual system the least risk, they dont need anyone (apomictic -> look up!)
on the other hand, at the higher end of the spectrum, some plants need to be non-related to the
mate (self-incompatible), or dioecy; where one plant only produces eggs and another plant only
produces pollen
*left for the washroom*
3. Populations and how they "behave"
carrying capacity; the maximum amount of individuals that can be supported in a given habitat; it
is density dependent
- limitation (density dependent):
- resource (space, food, light, nutrients)
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