This preview shows pages 1–2. Sign up to view the full content.
This preview has intentionally blurred sections. Sign up to view the full version.View Full Document
Unformatted text preview: BEHAVIOR AND NATURAL SELECT ION LIFE 53.5 – 53.6 & additional reading 53.5 Why do animal societies evolve?-Social behavior evolves when, by cooperating, co-specific individuals can achieve, on average, higher rates of survival and reproduction than they would if they lived alone. 53.5.1 Group living confers benefits but also imposes costs-Living in groups may confer many types of benefits . It may improve hunting success or expand the range of food that can be captured. Living in groups can also increase defense from enemies. -The pigeons in a flock interfere with one another’s ability to find seeds . Social individuals may inhibit one another’s attempts to reproduce or injure one another’s offspring. An almost universal cost associated with group living is higher exposure to diseases and parasites . 53.5.2 Parental care can evolve into more complex social systems-In simple mammalian social systems, solitary females or male–female pairs care for their young. As the period of parental care increases, older offspring may still be present when the next generation is born. They often help rear their younger siblings. In most social mammal species , female offspring remain in the group in which they were born, but males...
View Full Document