Evolutionary Biology BIOL 3350 Dr Lisa Rapaport Lecture 11 Part 1 Notes I II III IV V VI VII Sexual Selection Parental Investment Darwin noticed differences between males and females in morphology and behavior A Females are less involved in actively pursuing and finding mates than B Example Peacock tails found in males are much more colorful detailed than the tails of females Sexual selection A The males have traits that are designed to help them to compete with males other males B Females tend to do the choosing of mates C Males tend to have distinctions that make them stand out more and increase females ex bright colors Anisogamy A Males small gametes B Females large gametes C The female egg is the largest single cell in the human body Daily energetic investment in gametes A Female investment in gametes is much higher than that of males among all of these different types of organisms B Females devote much more basal metabolic energy about 3 Anisogamy and mating effort in fruitflies A Stored offspring produced by each individual B If males really are focusing their efforts on mating success they should benefit more from each additional mating that a female should A female should be investing more effort into each individual offspring compared to males C Theoretically If males could maintain an infinite number of matings they could obtain an infinite number of offspring D Major difference in the payoffs of males and females from mating success E Males gain more from each additional mating while females do not Reproductive success in male versus female function in bladder snails A The slope of the line was steeper for males than it was for females B Dotted line is where they included individuals that mated at least once C Solid line is where they included the individuals that did not experience any mating Not sex specific investment specific A The reproductive success of females is more skewed B Pipefish females invest more into the gametes but lay the eggs in the male pouches until the eggs hatch 1 C Most of the females had no offspring at all D The relationship between mating success and reproduction success is steeper for females than for males not as dramatic as the steepness for bladder snails E Sexual selection acts more strongly on female pipefish than male pipefish F Sexual selection is not gender specific instead it is investment specific and can different from one species to another Elephant seals A Males benefit more by additional mating B Females invest more yet males benefit more 18th century Sweden A Higher percentages of males and females with no children B The graphs of males and females are very similar to one another C Strictly monogamous each man was only allowed to have one wife and each female was only allowed to have one husband thus the reproductive success of the male was the same as the reproductive success of the female X Alex Joseph and his nine wives A Alex Joseph s reproductive success was much higher than any one of his nine wives B Female reproductive success tends to go up a little going from polygamy to monogamy the male reproductive success remains about the same going from polygamy to monogamy C However the variance difference between most successful and least successful of reproductive success was much larger in the polygamous system than in a monogamous system Degree of sexual dimorphism corresponds to male mating strategies A Males have slightly larger canines than females B Males have to compete very heavily in order to obtain a group of females Sexual dimorphism in apes A Gibbons are typically monogamous B Chimpanzees live in multiple male and multiple female groups they have mating frenzies or mating parties all of the males and females try to mate with one another C Gorilla males are almost double the size of females one dominant male in the group that mates with all of the females Sexual dimorphism in humans A Humans are mildly sexually dimorphic B Males have 60 more muscle than females C Males have 80 more upper arm muscle than females D Male jaws are more structurally robust than expected from body size alone VIII IX XI XII XIII 2