1. Improved Foraging Cooperative hunting may be favored by selection if individuals average at least as much food as they would get by hunting alone. Because food is shared by groups, success must greatly increase.
1. Improved Foraging Harris’s Hawk hunt in family groups – larger group sizes are more successful at killing cottontails and jackrabbits and average energy intake for groups of 5-6 is higher on average than in smaller groups.
I. Increased Competition -Dendropoma maxima, a vermetid snail that lives in coral reefs, secretes a sticky mucous net to trap plankton, then draws the net back in, eating the mucous and the palnkton. - When snails are grouped together, mucous nets overlap and stick together, so end up eating the nets of their neighbors. Thus, in areas of high density, snails must adjust for the presence of neighbors by retracting nets more quickly.
Some strategies to reduce parasite establishment 1)Some primates use toxic secretions from millipedes to clean their fur 2)Bees and ants collect and apply antimicrobial products to their nest material 3)Termites fumigate their nest with volatile antiseptic chemicals and enrich walls with antimicrobial feces 4)In bees, efficiency of antimicrobial defenses increase with degree of sociality 5)Bees, ants and termites remove corpses and create “graveyards” – sometimes exposing corpses to UV sunlight to kill fungal spores
III. Interference with reproduction Extrapair copulations, egg dumping