8. Communities are Composed of Interacting Species Flashcards
What is the basic idea of predation?
it is positive for the predator and negative for the prey
What is predation at the individual and population levels?
consumption and removal of an individual prey
a lower prey population growth rate
How do predators affect prey populations?
often lower the density of prey populations
How does an exotic predator affect prey populations?
can have devastating effects, the prey did not evolve with exotic predators and are thus less prepared for them
Can humans impact predation?
used to do something called “biological control” by manipulating prey populations by bringing in predators
OR
moving prey into areas where they have no predators (exotic prey) results in lots of population growth - like zebra mussels
Should we cull predators to increase prey populations?
over-predation is usually not an issue, human activities are the ones actually affecting prey populations
to know this for sure though, people usually run simulations to decide to cull or not
What needs to be accounted for when calculating to cull or not?
complex community relations, MSY of populations are dependent on one another (prey/predator dynamic partly determines MSY - the lower the prey the lower the predators because the latter eat the former)
How should sustainable harvest truly be decided on?
defined within a community / ecosystem context (not population), taking all of the relations into account (using a holistic approach as opposed to a reductionist one)
What is community sustainability?
the idea that harvest should be evaluated within a community context, the effects on the entire community and not simply a population
What are factors in community sustainability?
harvested populations live within biological communities
harvesting one species has effects on other species
optimal yield should be calculated within a community context (this is not widely adopted yet)
Is it easy to run simulations to decide to cull or not?
no, it’s very complicated to complete these calculations and simulations, applying MSY theory to just one species is complicated enough
What happens if we harvest the most valuable population and leave the others?
might be the best way to harvest, harvesting many species in a community could be problematic
