Biol 3350 1st Edition Lecture 16Outline of Last Lecture I. Overall effects of genetic drifII. Interaction of selection and drifIII. Interaction of drif with gene flowIV. Nonrandom matingV. GenotypesOutline of Current Lecture I. Sexual SelectionII. Why Sexual Reproduction?III. Origins of Sex Differences: AnisogamyIV. Daily Energetic Investment in GametesV. Anisogamy and Mating Efforts in FruitfliesVI. Reproductive Success in Male versus Female Function in Bladder SnailsVII. Bateman’s PrinciplesVIII. Not Sex-specific: Investment SpecificIX. Takes More Than Insemination for SuccessX. Alex Joseph and His Nine WivesXI. Mating SystemsXII. Sexual Dimorphism in ApesXIII. Sexual Dimorphism in HumansCurrent LectureThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.I. Sexual Selectiona. Females are less involved in actively pursing and finding mates than malesb. Darwin noticed two types of selection:i. Natural selection – survival and fertilityii. Selection to acquire mating1. Intrasexual selection – competition for mates2. Intersexual selection – mate choiceiii. Darwin noticed that males seem to have traits that allow them to have violent competition with males and traits that attract the opposite mates, while females were the ones doing the choosingII. Why Sexual Reproduction?a. Offspring sees only one of two possible alleles at each gene à recombination à new combination of allelesb. Each offspring is only getting half of the parental genesc. Mixing of genetic material of two parentsd. Two-fold cost of sexe. There must be a benefit from sex that offsets the costIII. Origins of Sex Differences: Anisogamya. Aniosgamy:i. Males produce small gametesii. Females produce large ones (the female egg is the largest single cell in thehuman body)b. A small, mobile gamete will be able to find the other gamete easier than a medium sized gametec. A medium sized gamete could provide nutrients for the individual to grow, but not as well as a large gameted. Therefore, anything in the middle is less favored than the two extremes à disruptive selectionIV. Daily Energetic Investment in Gametesa. Female investment in gametes is much higher than that of males among all of these different types of organismsb. Female devotes much more basal metabolic energy (about 3), while males only use about 1/1,000th of their basal energy towards gametes V. Anisogamy and Mating Efforts in Fruitfliesa. Bateman stored offspring produced by each individual and counted them using genetic markers to track which parents the offspring came fromb. 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 in each individual offspring compared to malesc. Theoretically - If males could maintain an infinite number of matings, they could obtain an infinite number of offspringd. Major difference in the payoffs of males and females from mating successe. Males will gain more from each individual mating à would predict that males put in more in the mating because they get a bigger payoffVI. Reproductive Success in Male versus Female Function in Bladder Snailsa. Solid line in where they included the individuals that did not experience any matingb. Dotted line in where they included individuals that mated at least oncec. Sexual selection is stronger in males because they are receiving more benefit from itd. Bladder snails are hermaphrodites, so these trends can occur in the same individual VII. Bateman’s Principlesa. Males can theoretically inseminate an infinite number of femalesb. Females have more investment from the outset, so a failed or poor-quality reproductive attempt is more costly than for malesVIII. Not Sex-specific: Investment Specifica. Pipefish females invest more into the gametes, but lay the eggs in the male pouches until the eggs hatchb. More variation in female success than malesc. Most females had no offspring at alld. Sexual selection in pipefish is acting stronger on females than males based on thesteeper line in the graph of femalese. Sexual selection is not gender based, but rather investment basedIX. Takes More Than Insemination for Successa. Select a mateb. Convince potential mate to select youc. Successful fertilizationd. Provide sufficient resources for offspring successX. Alex Joseph and His Nine Wivesa. His reproductive success was much higher than any one of his nine wivesb. Female reproductive success went up slightly when moving from polygamous to monogamous societiesc. Male reproductive success did not change much at alld. More variance in the polygamous system with malesXI. Mating Systemsa. Monogamy – not much variation between male and female reproductive successb. Polygyny – males have higher variation in reproductive successXII. Sexual Dimorphism in Apesa. Gibbons are mostly monogamous b. Chimpanzees lives in multiple male/multiple female groups c. Gorilla males are almost double the size of females and one dominant male in the group that receives all of the matings XIII. Sexual Dimorphism in Humansa. Males are 8-10% taller than females and 15-20% larger body weightb. Humans live in monogamous societies, yet they are mildly dimorphicc. Males have 60% more muscle mass than femalesd. Males have 80% more upper arm muscle than females (which is the equivalent difference found in gorillas)e. Males jaws are more structurally