Study Questions #11: Due in class on Monday May 1st

 

1. In Batesian mimicry complexes, the appearance of both the model and the mimic species evolve through directional selection. State how directional selection operates on the appearance of the model and on the appearance of the mimic species (i.e. how do their phenotypes evolve relative to one another).

Directional selection acts to make the phenotype of the model species different from that of the mimic, but there is also directional selection driving the phenotype of the mimic species to look similar to the model species. Natural selection acts on individual butterflies; through their differential survivorship and reproduction, the appearance of populations and of the species may be altered.

 

 

2. Describe an example of coevolution, stating the organisms involved and examples of specific traits that have coevolved in each as a result of the association.

Examples of mimicry, either Batesian or Müllerian, are also examples of coevolution, as are examples of plants evolving to attract specific pollinators, host-parasite relationships, interspecific competitive relationships, and predator-prey or plant-herbivore relationships (especially obvious among specialists).

 

 

  1. Behavioral ecologists often study animal behaviors in terms of "costs" and "benefits". What, specifically, do those terms "costs" and "benefits" mean — i.e. what exactly do they refer to, and what might scientists measure to gauge both costs and benefits?

The "costs" and "benefits" have to do with fitness costs and benefits of the behavior, i.e. costs and benefits that impact survival and reproduction. Measurement of the time or energy expenditure of the behavior and risks of expressing the behavior (attracting predators, for example) would be key data on costs. In assessing benefits, scientists would measure relative reproductive success and inclusive fitness of individuals expressing the behavior, as well differential survivorship.