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Lecture 17

BIOL 215 Lecture Notes - Lecture 17: Metapopulation, Serengeti, Intraspecific Competition

Biology (Sci)
Course Code
BIOL 215
Neil Price

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BIOL215 Lecture 17 Notes
Based on the Rosenzwieg-McArthur model, as you have more and more prey, there is stronger and
stronger intraspecific competition, so to stabilize the population of prey, you need less predators
which is why the curve goes down
Mutualism interaction is when coexistence is beneficial to both species. For the grouper and small fish
example, we are not saying that the relationship is an obligatory mutualism; both the small fish and
grouper can live apart and do fine. However, they will do better when they are living together
Mycorrhizae as a mutualistic interaction. Mycorrhizae fungi provide plants with greater access to
inorganic nutrients and are important to plant performance
Herbivory interaction: Herbivore consumes its prey but does not always kill it. Herbivore is a mild
form of predation
Predation interaction: Predator kills and consumes its prey. The herbivore-plant relation is one of
There is a high metabolic cost to defend oneself. The production of thorn takes energy, nutrients.
Thus, the plant's fitness level overall will decrease. A good example of a plastic functional response in
this case to herbivory suggests that herbivore will have a big impact on the growth of plants
The hypothesis of overcompensation in plant responses comes from the idea that herbivores may not
be all together so negative for plants. It suggests to a certain extent that as grazing pressure increases,
it might even be beneficial and lead to an increase in production. This may be due to intraspecific and
interspecific competition
Serengeti Plains is a good example of the herbivory interaction linked with the overcompensation in
plant responses due to grazing (Zebra eat first, then wildebeest, then Thomsons gazelle)
Parasitism interaction: Predators, parasites and pathogens influence the structure, abundance, and
distribution of population. It is a form of predation. At times, it may lead to killing the prey, but this
does not always happen
Parasite: An organism living in with or on another organism, obtaining benefit from it and usually
injuring it (i.e. Lamprey)
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