Predators can shape evolution in their preyUroplatus phantasticus Dendrobates azureus Cruziohyla craspedopus Dermal fringes

Predator evolution pushed by prey

Thamnophis sirtalis Taricha granulosa +/- tetradotoxin Ecological context Resistance to tetradotoxin Predator-prey coevolution

Snakes and cane toads Bufotoxin

Brood parasites; e.g., cuckoos and cowbirds Cuculus canorus European cuckoo Calls same Acrocephalus scirpaceus, Reed warbler Co-evolution to egg rejection

Social Interactions Actor and Recipient Fitness possibilities (offspring units) : 1. both actor and recipient increase their fitness: cooperative behavior 2. fitness of actor increases, fitness of recipient decreases: selfish behavior 3. fitness of actor decreases; fitness of recipient increases: altruistic behavior.

Maximizing fitness by selfish behavior

Conflict between cells and groups of cells Slime molds: amoeboid and slug forms Sporangium chtA mutant Selfish behavior Vegetative Reproductive

Altruistic Behavior The actor will perform an act – places the actor at a disadvantage – benefits the recipient Intuitively, the fitness of the actor should decrease, and the fitness of the recipient should increase. Natural selection should eliminated altruistic acts.

Cooperation and Altruistic Behavior Slime mold A gene for altruism csA allele: adhesion protein Cell differentiation in the slug 1. Cells that form spores: DNA perpetuated 2. Cells that form the reproductive stalk: die Therefore, sacrifice made by some cells for the benefit of others.

Paradox resolved by inclusive fitness For social animals, two categories of fitness 1. direct fitness = personal reproduction. But, because it is likely that relatives share some of the same alleles… 2. indirect fitness = assistance of actor results in greater success in raising relatives to reproductive maturity. Actor’s fitness increased by an increase in frequency of alleles shared with relatives.