Question

During the lecture section of this course, we recently discussed the evolution of adaptations by the process of natural selection. Remember that adaptations are structural, behavioral, and physiological characteristics of a species that have evolved by natural selection to help the organism survive and reproduce. We also talked about competition among species and evolutionary “arms races” between certain species. An example we discussed in class is the predator-prey relationship between wolves and deer (i.e., wolves prey upon deer; thus, wolves and deer are strong forces of natural selection on one another because of their close relationship with one another). There are other examples of coevolution and evolutionary arms races (including that between nest parasites and their host species).

 

During lab today, we will watch the BBC documentary “Cuckoo: Evolutionary Cheat” narrated by David Attenborough (approximately 50 minutes in length). The video mostly focuses on the interactions between two bird species (the Common Cuckoo and the Reed Warbler). The Common Cuckoo is a nest parasite of the Reed Warbler, meaning that it lays one of its eggs in the nest of the Reed Warbler so that the warbler raises the cuckoo chick. The Common Cuckoo gets away with not building a nest or raising its own offspring!

 

These two birds are in an evolutionary arms race and are coevolving. In watching the video, you will notice that the Common Cuckoo has several behaviors and other characteristics that have evolved to help it parasitize nests of other birds (including the Reed Warbler). Likewise, the Reed Warbler exhibits behaviors that can help it prevent its nest from being parasitized (though some parasitism still occurs). Though the narrator and other people in the video may not explicitly state what these adaptations are, carefully watch for characteristics (including behaviors) that you feel specifically aid the Common Cuckoo in nest parasitism and those that are attempts by the Reed Warbler to counter (respond to) the nest parasitism efforts of cuckoos.