- Lecture 12: Species Interactions
- Are you happy with this formula?
- How would you deal with this?
o Come with up a new formula?
o Use the exponential?
o Use the geometric?
o Alter the formula to reflect what’s going on?
What’s missing? Interactions between species and populations
- So then, what do we have to consider in the improved formula?
o We deal with more than one population
Each population has its own carrying capacity
o The individuals of each population interact with those of the other population
They influence each other’s carrying capacity if they share a limiting resource
o We need to consider population densities of both populations when studying density-
dependent processes of both populations
o A decrease in carrying capacity for the population under consideration
- Species interactions vary in effect
o IMAGE REMOVED
- Interactions are agents of natural selection
o Finches on the Galapagos island
o Seed sizes on the different islands and the finches that inhibits on the islands have
different size beaks
o Small seeds are easier to eat, so the diet is mostly small seeds
o The large seeds gets to reproduce and became more than small seeds
o Birds have harder time to find small seeds, and if they have small beaks, it gets hard to
o The beak size gets bigger and bigger over generation to deal with the large harder to eat
- What were the selective forces here?
o Bat populations from two areas
o Ears for hearing and dete