Physical & genetic fitness

 Brian Wallheimer's article "^[1], could be used in connection with Explain how animal responses can be affected by natural selection, using two examples. option E1- Stimulus & response.
This is an interesting incidence of learned behaviour by these birds that could be referred to in option E3 Innate & learned behaviour.  I asked my students to write a response to Discuss how the process of learning can improve the chance of survival for homework.

Andrew DeWoody, a Purdue University professor of genetics, found that the higher the frequency of a male bird's song, the more genetic diversity that bird has, making him a better mate for breeding. DeWoody's research points to genetic fitness which in turn refers to aspects of natural selection for the trait.

"Animals that are heterozygous, or have genetic diversity, are often bigger, stronger or can run faster."

Studying ocellated antbirds, Phaenostictus mcleannani in the tropical forests of Central America, DeWoody and Johel Chaves-Campos they noted that the antbirds follow army ants swarms that attack and destroy any living thing in their path. The birds jump just in front of the swarms and grab grasshoppers and other insects that try to escape the ants.

With reference to the calls the antbirds make, DeWoody's research related the recordings of calls to samples of DNA from the birds. The results suggest that genetic diversity in antbirds affects their physical abilities to produce certain sounds. "Males that are genetically diverse, and therefore expected to be in better physical condition, are able to produce sound frequencies that males with less genetic variation are unable to reach," Chaves-Campos said." (Wallheimer, 2010)
 

Animals that defend territories and compete for mates in any species need to have some control device, here the quality of song is the indicator of fitness.  Potentially, those males with more varied calls could intimidate others from attempting to establish themselves within the territory.