MacArthur

What was the underlying theory behind MacArthur's study and what was his major prediction?

believed that density dependent events play a large role in these populations, the 5 warbler species are primarily regulated by density dependent factors - increase when they are rare and decrease when they are common Competitive exclusion principle - interspecific competition is weaker than intraspecific competition What different resources are they using, in what ways might they differ in their ecology so that each species is limited by some different resource?

What mechanisms of interspecific competition were suggested or discussed in MacArthur's work, and what evidence did he provide that interspecific competition is important for these warbler species?

competing indirectly by exploiting foods that another species is able to eat, making it less available has caused evolutionary shift in ecology that allows species to have separate diets

How did MacArthur's study follow the hypothetico-deductive method?

he was testing a specific theory, trying to falsify or support it tested deductions from that theory, deductions=predictions predicted that they would have niche differences, limited by different factors

How did the five warbler species differ ecologically, and why is this important to the study?

lived in different parts of trees, fed at slightly different times of day, generally different diets, movement patterns, hunting style

What evidence does MacArthur provide to suggest that the species differences he found are the result of evolution via natural selection? What evidence suggests plasticity, i.e., the absence of strong genetically determined traits?

natural selection: warblers have differences in morphology that are linked to differences in feeding ecology, e.g., beak size ; also, some differences persist throughout the year, even in their wintering migration, increasing the likelihood that there is a genetic basis for the traits plasticity - Cape May and Backburnian warblers could increase clutch size in response to spruce budworm outbreak

Was MacArhur's study experimental?

no, he did not manipulate anything his study was hypothesis driven - he was looking for specific things motivated by his theory

What was MacArthur's study system (including level of organization), and why was it a good choice for his study?

used 5 warbler species of the same genus with relatively similar ecological niches evolutionarily, these species share a common ancestor, as they are of the same genus migrant and insectivorous birds share the same habitat - boreal biome, with spurs and spruce, etc. similar feeding habitat