Question

Many people define an adaptation as a trait that improves the survival (and eventual reproductive) chances of an organism. Under what circumstances might a trait that improves survival in an individual actually be selected against because it does not improve reproduction and ultimately fitness? Think about behaviors that might increase an individual's chances of surviving, but would inhibit, for example, finding a mate or parenting. To answer this question use Chapters 2 and 3 in Alcock and the lecture notes on adaptation, HOWEVER, be very careful not to use a group selection argument in this answer. Remember that we are always talking about evolution at the level of the individual, and survival and fitness for the individual, not the group.

Answer 1

Answer: Broadly there are two levels of adaptation; first class of adaptation is called survival adaptations related to physical survival in adverse environmental conditions like very high or low temperatures. And as mentioned in the question second class of adaptation is for reproduction that involves some traits and behaviors and help individual to compete for mate.

Part-1: Under what circumstances might a trait that improves survival in an individual actually be selected against because it does not improve reproduction and ultimately fitness? In reproductive survival, there are two processes first is intrasexual competition and other is intersexual competition. In intrasexual, one sex competes against each other and winner gets the mate. In second process, individual deals with sexual preferences in mate choice. There are some circumstances that can affect reproductive survival for example, an individual's status within group, higher status gets more attractive mate. Virginity of an individual is also important factor in some cultures for reproductive success or getting mate. Physical strength, specified fears also affect reproductive success or attracting mate in human as well as in animals, and presence of competing genes is also important for reproductive success.

Part- 2: There are some behaviors or traits that are helpful in survival but not in finding mate or in reproduction and ultimate fitness. These traits are aggression or violence and appeasement, thinking, habitat preferences, intelligence etc can inhibit for attracting mate and ultimately in reproductive success. Individual with these traits can have survival success but if he/she is high on aggression, differences in thinking, preferences are different and have low intelligence can struggle to get mate and sexual survival. Sexual strategies theory—anchored in sexual selection theory— predicts specific similarities and differences in man and woman’s mating preferences and strategies. Whether an individual seeks short-term or long-term relationships, many personality, social, cultural, and ecological factors will all influence who his/her partners will be.