PSYC 311 1st Edition Lecture 14- Warning cries o Kin selection o Reciprocal altruismo Chimps/baboons ganging up/stalking leopard Social insect ganging up on you (bees/ants)I. Defensive Strategies in Social Animals (slide 42)a. Dilution – decrease of threat to any group member as group size increasesi. Increased herd size may attract more predators b. “selfish herd” – groups whose members increase the probability of escape by using the herd as a shield, distractor, or dilutor II. Continued, strategies to avoid being eaten a. Fighting back i. Usually a plan of last resortii. Noxious chemicals – blister/bombardier beetlesiii. Mechanical mechanisms (scorpions)III. Approaches to Comsummatory (feeding) Behavior a. Strong C/B proviso for all mechanisms b. Generalist feeders – eat anything that doesn’t eat them first i. Omnivores – exploit whatever is available ii. Not adapted to a specific diet – cannot compete with specialized diets 1. Sensory systems widely arranged 2. Teeth – not specialized 3. Digestive mechanisms digest variety of foodsiii. Taste aversion (well developed in generalists)1. Generalists - might ingest something that makes them sick a. Can switch food sources as a function of seasonal variations in food availability b. Usually found in temperate zones where there are seasons c. Specialists i. Types 1. Fructivores (fruit)2. Herbivores3. Carnivores4. Insectivores 5. Others more specific (ex. Nectar)ii. If specialists are competing with generalists for a specific food source, specialist will win 1. Mechanism for finding that food is much better (not in seasonal areas)a. Both specialist and generalist are susceptible to evolutionary pressure i. No two animals can occupy the same ecological niche 1. White rhino and black rhino 2. Well adapted to a specific diet d. Diversity of ingestive systems i. Convergent evolution – filter feeders 1. Oysters, clams, baleen whales ii. Coevolution 1. Food sources change to better accommodate/avoid predators a. Flower shapes change to optimize pollination by bird/insectiii. Small particles 1. Pseudopodia (amoebas), cilia, flagella, nematocysts (jellyfish)2. Insectivoresiv. Larger particles – swallowing of particles or substrate containing the food (earthworms)1. Scraping, boring – snail teeth, algae eaters v. Seizing, constricting, swallowing (snakes)vi. Mastication – chewing, shredding 1. Beaks, teeth2. Bird beaks evolved to exploit different types of food 3. Teeth have evolved to fit a given type of food (which can be used to infer diet of extinct
View Full Document