Lecture Notes: Weeks 5, 6, and 7
Lecture Notes: Weeks 5, 6, and 7 123-01
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Date Created: 11/05/14
Week 5 Lecture Notes October 20 2014 A Biology of Sexual Orientation i Biological Assigned Sex the anatomical physiological and genetic characteristics associated with being male or female ii Gender Identity the psychological sense of being male or female iii Sexual Orientation an enduring pattern of emotional romantic andor sexual attractions to men women or both sexes B Gender Identity in Humans i We know very little about gender identity ii Nature vs nurture debate applies iii Was it caused by something that happened in the womb or something that happened personally We don t know for sure iv Hijra occurs in South Asian countries Usually men who are transgender females Most have not been castrated and still have male organs They challenge all of the gender norms that we are used to and are considered a third gender A lot of them live on the fringes of society Third gender is completely recognized in India However in many instances transponders are treated horribly and abused in India C Sexual Orientation in Animals i Homosexuality in animals is documented in 4001000 species ii Occurs in mammals birds snakes invertebrates etc iii Why do animals exhibit same sex sexual behavior Assertion of dominance Prisoner Effect Isolation from females causes males to mount one another Social glue bottlenose dolphins Forms bonds between animals reduces conflict reconciles conflict Practicing D Sexual Orientation in Humans i Alfred Kinseywrote Sexual Behavior in the Human Male 1948 Studied those who practiced same sex sexual behavior Data widely criticized and not considered to be true by scientists today Said that 10 of people were homosexual ii 2013 study says that 16 of peopled identified as gay 977 as straight 15 bisexual iii Very difficult to attain accurate data about this topic iv However this data caused gayrights groups to lash out against the 2013 study They said it underrepresented their population E Sodomy i Anal or oral sexual activity between people or between a person and an animal ii Some say it s any sexual activity that isn t for reproduction iii Legally it is defined as same sex sexual activity homosexuality F What Does the Science Say i About 10 of the human population is LGBTIQ ii Homosexuality can be heritable from twinsibling studies This means that there is a genetic component to homosexuality There is no gay gene but there is a genetic basis iii Having more older brothers increases the likelihood a male will be homosexual This could be because of what is going on in the mother s body as she produces all of these males iv There are anatomical and physiological differences between the bodies and brains of homosexual and heterosexual people v Testosterone causes male and female brains to develop differently INAH3 size is effected by sex and sexual orientation Straight men have larger INAH3 than women For gay men it is smaller G Pheromone i Chemical signal that alters behavior or physiology of others ii Aggression mating feeding living in groups iii Menstrual Synchrony women who live in close quarters end up having synchronized cycles Caused by human pheromones Scientists do not believe in menstrual synchrony anymore iv Body odor influences attractiveness in humans Week 6 Lecture Notes October 27 2014 A Hormones and Contraception i A A Berthold father of modern day hormone study Wondered what causes typical male anatomy and behavior in roosters Removed testes of normal roosters combs and wattles became smaller roosters had no interest in hens weak crow and listless fight behavior Castrated cocks one testis was replaced comb and wattles became normal interest on hens developedmae rooster characteristics restored ii The Coolidge Effect sex drive often lowers with an organism who continually mates with the same organism New mateincreased sex drive iii Eunuch people with removes testes or even removed penises Often served as guards in China iv Monoestrous the females in the species are fertile only once a year v Seasonal Polyestrous Females are fertile multiple times but seasonally vi Monthly Estrous Menstrual fertile once a month humans vii No Estrous Females are fertile all the time B Hormones and Contraception in Humans i Brain makes hormones The hormones are gonadotropins LH FSH These stimulate gonads ovaries and testes and cause them to produce estrogen progesterone and testosterone ii Sex Steroids estrogen progesterone testosterone iii Sex steroids are brought back to the brain then inhibit the gonadotrophins iv Anabolic steroids causes people to not produce their one testosterone serves as artificial testosterone C The Female Menstrual Cycle i Days 14 As woman menstruates the lining of the uterus decreases ii Days 414 lining of uterus builds up as a result of the increase of estrogen Getting ready for possible fertilization iii Release of egg ovulationCaused by high levels of estrogen on day 14 Female is fertile when ovulating Awoman will NOT ovulate if the estrogen levels do not get high iv Days 1428 estrogen levels go down progesterone levels go up Lining maintained no bleeding because of high levels of progesterone Progesterone is like the pregnancy hormone low levels during pregnancy causes bleeding ie miscarriage Drop of progesterone from previous cycle causes menstrual cycle D The Birth Control Pill i 3 weeks of hormone progesterone pills and 1 week of sugar placebo pills so that the woman does not get out of the habit of taking the pill ii Women on birth control have very light periods since the small amount of progesterone is preventing the lining from decreasing so when she bleeds she bleeds very little E The Shot depoprovera i Progesterone Stays in the blood stream for 3 months Lazy woman s birth control Woman will not have her period during this time F The mpant lmplanon i Progesterone implant Progesterone can last in blood stream for 79 months G Chemical Castration i Not permanent Injection of progesterone stops man from making testosterone Controversial because it may not work and sex offenders want it to control their urges H The Morning After Pill Plan B i High dose birth control pill Contains progesterone and estrogen the amount that would be found in 4 days worth of birth control pills ii Some call this an abortion pill You can only say this if you think life begins when an egg is ovulated iii This pill blocks ovulation Won t work if sperm has already attempted to fertilize egg Won t work if the woman has JUST ovulated I The Abortion Pill Mifeprex i Only works the first 79 weeks of pregnancy ii Blocks progesterone causes a period ieinduces miscarriage J How to Control Wildlife Populations i Wildlife contraception darting ii Feral Bison of Catalina Island inject foreign protein into Bison body attacks it makes antibodies Antibodies bind to egg cells and kill them October 29 2014 A Sex Pheromone i Chemical signal that alters sexual behavior of another individual ii species fertility receptivity quality iii Travels slowly lasts long travels far iv Flehmen Response Animals are exposing an organ in their bodies that search out pheromones v Vomeronasal Organ Delivers pheromone signals to brain Different pathway than olfactory signals vi Males use pheromones to detect receptivity if a female will mate vii Also tell males the quality of the female viii Pheromones can prevent inbreeding B Inbreeding i Greater chances of homozygous recessive individuals ii Can uncover diseases normally hidden ie sickle cell anemia and cystic fibrosis C Pheromones Can Prevent Inbreeding i squirrels learn their own scent use as reference for how to react to others Armpit Effectquot ii To test this test cubes were rubbed on strangers some related more than others to the test animals Researchers examined how long test animals investigated the smelly cubes The less related the other individual the more the scent was investigated D Males Use Pheromones to Compete for Mates i Hippos rub their feces on themselves E What About Humans i Vomeronasal organ may not have sensory function and may not even exist ii Genes that are involved do not function iii Butwe do produce pheromones involved in mating iv Humans are the Naked Ape We are the only great apes without furWhy did we lose our fur Perhaps to avoid overheating or to minimize parasites Could also be the ability to signal our health to potential mates v Why do we still have some fur Perhaps to lodge pheromones in sweat glands Body odor influences attractiveness F Symmetrical Faces Attractive Odors i there is no universal favorite odor ii Certain people find certain odors attractive G Mates Seek the Best Immune System Genes i the more diversity in alleles the better the immune system ii How can you tell a person s immune system genotype Just sniff iii Published study men wore tshirts for 2 days women were asked to rate the odors genotypes determined using blood tests Found that women like dissimilar menuness they re on the pill This is because the pill mimics pregnancy hormonally therefore they do not have mating on their minds they want to be around relatives for companionship Week 7 Lecture Notes November 3 2014 A How to Find One Definition For All Species i Species individuals capable of exchanging genes ii Population individuals of same species in same area iii Baboons females show males their quality during mating season through sexual swellings their butts swell up B Natural Selection i Those with better traits survive better and reproduce more ii Pass on more of their alleles to the next generation iii Nature selects which alleles get passed on and which don t iv Variation is necessary for natural selection to act C How is Variation Made i Meiosis mutation and sexual reproduction D How Does Natural Selection Cause Evolution i Variation with a genetic basis heritable ii Those with the best trait reproduce more iii Alleles for the best traits become more common iv Evolution makes adaptations Improves ability to survive and reproduce in a given environment v If natural selection acts similarly similar adaptations will evolve E Evolution i A change in allele frequencies for a given gene in a given population over generations ii But as the environment changes what constitutes an adaptation changes If costs outweigh benefits the trait may be selected against iii Traits may become more or less common over time iv Charles Danivin Wrote The Origin of Species Went on a voyage around the world to collect information for this book Used artificial selection to figure out natural selection v Population average changes individuals do not change vi Only heritable traits evolve vii Heritable traits have a strong genetic basis can be passed on viii Even beneficial traits can t evolve if they can t be passed on viv Changes caused during the lifetime caused by the environment are not passed on x Evolution does not respond to need If a species really needs a trait it will not evolve unless there is a heritable variation present and it is tied to a greeter reproductive success xi Evolution does not act for the good of the species or group What if allele caused an individual to act to reduce its own survival and increase the survival of unrelated others Selfishness will spread throughout the population F Evolution by Natural Selection i Species change over time ii All species are related by a common ancestor G Evidence that Populations Change i Gonorrhea disease that was horrible until the invention of antibiotics ii Now there is super gonorrhea resistant to those antibiotics iii This is strong evidence for change in allele frequencies in populations over generations iv Phylogenydepicts relationships between species and their common ancestors v Speciation one species splits into two H Evidence that a Species Comes from Another i Similarities in anatomy ii Implements for grasping digging running swimming flying would not be made from the same bones if not for a common ancestor iii Vestigial traits are evidence of relatedness of species iv Some species are links between two groups evidence of relatedness ie Archaeopteryx is a link between birds and dinosaurs I Every Beneficial TraitAso has Costs i This is why every member of a species may not share a beneficial trait J Humans are Still Evolving i One example is the immunity that they have developed to diseases ii People in big cities need stronger immunity to diseases iii Adults can still digest milk This has been described as the most spectacular mutation in recent human history Example of convergent evolution iv There is natural selection occurring in present times Example Ebola virus November 5 2014 A Costs of Mating i Tungara frog Sings to females with a simple or complex call Risk of attracting a predator A bat listens for the calls of these frogs Both females and bats prefer the complex call ii Males usually pay the costs of mating This may be due to the Fundamental Asymmetry of Sex iii Fundamental Asymmetry of Sex sperm is cheap eggs are expensive to make Females invest more males compete Natural selection favors females being very choosy when it comes to picking a mate while males should simply reproduce as much as possible Example 40kg female orangutan carries fetus for 8 months gives birth nurses for 3 years protects for 78 years 70kg male contributes a few grams of semen only iv Sexual Selection Charles Danivin proposed this Not a struggle for existence but a struggle of males for possession of females The result is not death to those who are unsuccessful but few to no offspring v Bowerbirds are under strong sexual selection They build structures made of twigs bowers as part of male mating display They decorate their bowers as well They display constantly for females but most males get to mate 0 times while some males get all the matings Every female mates with 1 male per season and raises the young alone Why do males build bowers To prevent females from being scared during courtship The more the female crouches the more intense the male display vi Males who pay more attention to females during courtship better attain mates vii Giraffes Necking Can be deadly Energy delivered can be relative to length of neck viii Handicap honest signal of how good the male is The fact that the male can live with a handicap shows he is superior to other males B But Why Do Females Care About Men s Courtship i Direct Benefits territory protection edible nuptial gifts ii Healthy Mates a female that chooses very carefully may choose a male that has no infections In Bower birds more decorated symmetrical and neat the bowers indicate fewer STDs Some of the best Bowerbirds steal decorations iii Good Genes different genes from those of female Genetically based survival traits For instance the better bower may indicate a bigger brain iv Sexy Sons hypothesis females prefer making attractive sons even if it reduces their survival C Consequences of Sexual Selection i Traits that may be bad for survival ii Sexual Dimorphism the differences between the two sexes Males look very different from females since they had to court females D How Could the Process of Sexual Selection Start i Carotenoid pigments gives males all different colorsln humans they fight cancer In fish and birds they help them resist infections ii A Sensory Bias for Orange females may have a sensory bias that causes them to love the color orange Could be because of the orange foods that they eat the color makes them gravitate toward orange foods and orange males iii Taking advantage of a female bias may have originally mimicked fruit colored trait was successful passed down to other generations E Sexual Selection in Plants icoorfu fragrant flowers
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