8.1 Responses to the Environment

Organisms respond to cues: taxis (movement toward/away from a stimulus), kinesis (random movement changes), phototropism in plants (bending toward light via auxin).

Innate behaviors are genetic (fixed action patterns); learned behaviors include imprinting, classical and operant conditioning. Photoperiodism controls flowering and migration timing.

Animals communicate by visual displays, sounds, chemicals (pheromones) and touch — honeybee waggle dance shows food direction and distance. Cooperative behaviors (altruism) can be favored by kin selection when relatives share genes.

Behaviors that increase fitness are selected for.

Worked example: Why do ground squirrels give alarm calls that put themselves at risk? → Kin selection; neighbors are often relatives sharing their alleles.