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Habitat selection Habitat selection Habitat selection Habitat selection Habitat selection Habitat selection Hive location as a group decision process Hive selection is a balance between spacing and site quality: •Spacing force: dependent on resource scarcity (northern vs. southern) •Site quality force: dependent on cavity and opening dimensions Habitat selection: sex specific disruption in belding’s ground squirrel •Key points here are: •Resource defense •Competitive release •Avoidance of in-breading depression The effect of in-breading on reproductive success Differential dispersion insures out-breading Migration: how could it have evolved? Arctic tern The evolution of habitat selection: The Least tern Adaptive landscapes: Evolving from one state to another •Sewall Wright developed the concept of the adaptive landscape as a means to describe changes in fitness resulting from changing evolutionary pressures over evolutionary time. •This is a heuristic that characterizes the complex summation of evolutionary forces. •Can be used to describe population-level changes in gene/allele distributions for polygenetic traits as a function in there changing fitness values •Can be used to describe the ecological forces (that act on gene/allele distributions for polygenetic traits) on phenotypes Concepts: Directional selection: The systematic culling of a population from one side of a distribution and survival of the portion of a population on another. Stable Equilibrium: a set of traits existing in a population over evolutionary time because changes in those traits are detrimental. Unstable Equilibrium: a condition where one or multiple selective pressures emerge and enhance the likelihood of divergence (speciation). Local optimum: a region of the landscape that is adaptive and isolated from other adaptive peaks. Genetic Drift: under conditions of no selective pressure random mutations change genotypes/phenotypes in random directions. Allows a population to “explore the fitness surface Habitat selection: the Lesser tern
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