What are the advantages of sexual reproduction?
limit harmful mutations-those with the most harmful ones tend not to reproduce, generate beneficial gene combinations-adapt to changing environment, adapt to all aspects of constant environment
What are advantages of asexual reproduction?
quicker, easier, more offspring
Explain the following regarding gametes: only the average is selected against.
In Disruptive Selection, a form of natural selection, the average values are selected against so that the distribution of the trait becomes bimodal; big gametes for ova, small gametes for sperm
What are 3 means of sex determination?
sex chromosomes, social, temperature
Which cells in the body are diploid and which are haploid?
gametes are haploid, all other cells are diploid
Describe the lineup of replicated chromosomes in the metaphase stage of meiosis vs. mitosis.
In metaphase of meiosis 1, pairs of homologous chromosomes line up together. In mitosis and M2, chromosomes line up as single individuals
Describe the X and Y chromosomes. Which gene confers maleness?
Females- XX chromosomes
Males-XY
Y chromosome typically contains the SRY gene which confers maleness. SET gene is sex determining region on the y chromosome
How can an XX individual develop as a phenotypic male?
XX individual receives SRY gene through crossing over
What is a hermaphrodite? Do hermaphrodites fertilize themselves?
Produce both egg and sperm; do NOT fertilize themselves
What is the supposed rationale for male peacocks to have such huge tails, and for male bowerbirds to build such fancy, but non-functional bowers?
Display to females their health and quality of genes; bowerbirds make up for lack of show through bowers
Describe the reproduction strategy of male and female seahorses. Which sex supplies the most nutrients to the developing young?
Males get pregnant and give birth after female produces ova and deposits them in a deep cavity in male where they are fertilized, pouch closes for ~10 days then babies come out. Nutrients come from egg yolk provided by female
What are 2 potential advantages to female promiscuity?
Obtain resources from multiple males, increase total number of offspring, obtain better quality sperm, safeguard offspring from new dominant male
Describe the process of paternity testing.
Gel electrophoresis
1. DNA samples from the mother, the offspring, and two possible fathers are broken into fragments with an enzyme.
2. The fragments are then separated into bands, according to size, by gel electrophoresis.
3. Every band of the offspring
Describe the theory of kin selection. What is a rationale for its existence?
Altruistic behavior may enhance inclusive fitness; Lions, bees and some humans: unequal chance of mating; Females contribute the major resources, but they are able to select a mate that will protect them and take care of their kids.
In some circumstances
Describe sexual activity among Bonobos.
Nonproductive sex for sake of alliance formation or conflict resolution; make love, not war
front-to-front copulation
male-female, male-male, female-female sexual encounters
engage in sex before dividing a new food source
Female bonobos are receptive duri
What part of the male genitals is homologous to the female outer labia?
Scrotum
What part of the male genitals is homologous to the female inner labia?
Shaft of penis
What are the corpora cavernosa and what is their function?
Erection in penis/clitoris when filled with blood; surrounding blood vessels constrict to prevent blood from flowing away
How does the vagina maintain an acidic pH? What is a benefit of that?
Good bacteria maintain acidic pH; inhibits growth of bad bacteria
Neutral pH is better for sperm; facilitated by lubrication from vaginal mucosa
What is the G-spot? What part of the male anatomy may it be homologous to?
front (anterior) wall of vagina, 1-2" in from front entrance; homologous to male prostate
What is endometriosis? Uterine fibroids?
Endometriosis: bits of endometrium in abdominal cavity; treated with oral contraception, surgery
Fibroids: noncancerous tumors of smooth muscle; painful, sometimes bleeding
Where does fertilization occur?
Fallopian tubes
How is the ovum moved along toward the uterus after ovulation?
Cilia produce a current in the fallopian tubes to move the ovum, and sperm swim against this current to reach ovum
What are granulosa cells, and what are their 3 functions?
Nourish oocytes, prevent 1st meiotic division (surround oocytes, gap junction), produce estrogen from testosterone produced by thecal cells
What are thecal cells, and what is their main function?
Produce testosterone, which is then converted to estrogen by granulosa cells
What are 3 factors that affect the risk of breast cancer?
Genes (BRCA1 & 2), age (85% are over 50), early menarche or menopause, no children, alcohol, obesity, lack of exercise, contraceptive or post-menopausal hormone treatment (only slight effects)
Prolonged nursing decreases risk
What are 3 physical signs of sexual arousal in women?
Erection of clitoris
Vasocongestion in labia and vaginal walls; vaginal walls change from pink to purple as blood pools; vasocongestion plus contraction of muscles in the vaginal walls and pelvic floor = tighter squeeze on penis, which is better for both
What are pheromones, and what are at least two possible functions?
Synchronized periods-lengthen or shorten menstrual cycle; attractivity
What are some environmental factors that can influence menstrual or estrous cycles?
Synchronized periods when women live together, stressful events, illness suppresses female sexual behavior
Perinatal events: proximity to brothers in uterine horn during gestation increased estrous cycle length and reduced attractiveness in female rats an
What hormone/neurotransmitter is important for promoting smooth muscle contractions and pleasurable feelings of orgasm?
Oxytocin
What are 2 sources of fluid that may be ejaculated by some women at orgasm?
Small amount of opalescent fluid, discharged without much force & Larger amount of clear fluid (urine containing prostatic acid) propelled with force
What are proceptive behaviors? What are 2 proceptive behaviors of female rats?
Courting behaviors
Approach males then hop and dart away; wiggle ears
What brain area is especially important for female receptive behavior?
Ventromedial nucleus of hypothalamus (VMH)
What is lordosis, and why is it important for rodent sexual behavior?
Lordosis-Receptivity: mating posture (arching of back) in response to stimulation from the male. She deflects her tail and stands immobile to aid the male's penile insertion.
What is the major effect of the forebrain module on female rat sexual behavior?
Inhibits lordosis
What is one way in which the hypothalamus influences lordosis in female rats?
Responds to steroid hormones; produces proteins and peptides which are sent to the midbrain. Is important for lordosis.
Describe the pacing of copulation by female rodents.
Mount (~8 sec), intromission (~18 s), ejaculation (50 s)
pacing enhances reproduction
Why is the "vaginal code" important?
optimal pattern of stimulation --> luteal phase
What did Jill Becker find regarding dopamine in the mesolimbic tract of female rats while they were mating?
Dopamine is released in the nucleus accumbens only when mating at their preferred pace