sex Flashcards
proceptive
referring to a state where a female advertises her readiness to mate through species typical behaviour
sexual attraction
women peaks during fertility - for most species coapulation is not possible without the womens cooperation
mysterious
can also be because of same place at the same time
first stage in bringing male and famales together
animals emit stimuli that attract members of the opposite sex
also many associate it with being ready to reproduce
appetitive behaviour
actively doing something that makes sex more probable
for humans it could be getting dressed up and going to the club
appetite for sex
behaviours designed to attract mates (proceptive)
consummatory behaviour
corresponds to copulation or coitus in many species
postcopulatory behaviour
characteristic post-coital behaviours, often associated with diminished sexual appetitie for some period of time
cleaning up
refractory period
for awhile after copulation, males and/or females will not mate again
varies greatly between species
coolidge effect
refractory period is considerably shortened if a refractory animal is provided with a novel partner
- will mate sooner if with a new partner
especially true of males, but also some females
Heat/estrus
a period of greatly increased sexual receptivity
receptivity is low or absent outside of estrus
often coincides with ovulation, or whatever conditions are necessary for reproduction
at the same time as ova being spread
female often the one to choose when coapulation takes place
some species will not have sex outside this period
copulatory lock
remarkable adaptation - male’s penises swell and lock into place for awhile
can be a firm lock
maximizes the probability of paternity, minimizes copulation by other rival males
ring doves
male courts female through bowing
femle wing flips if sight of good male causing hormonal changes in female - if seperated by glass and can only see each other
makes male excited, so he starts making a nest
makes woman excited and she is ready to incubate and feed, egg lay
each stage has a hormonal correlate that is largely controlled by the behaviour of the other mate
lordosis
a female’s receptive posture
four legged animals in which hindquarters are raised and the tail is turned to one side, facilitating intromission by the male
estrogen
secreted at high levels at beginning of ovulatory cycle and gives rise to proceptive behaviour
peaks before ovulation
stimulate production of testoterone
progesterone
sudden increase before ovulation maximizes proceptive behaviours and lordosis (receptive behaviour)
ovariectomy
eliminates sexual responses
lordosis can be partially restored through estrogen replacements
behaviour requires both hormones
vaginal code (cervicohypothalamic projection)
need penis hitting the cervix - mechanical stimulation - will signal to hypothalamus to get ready for pregnancy
pseudopregnancy
females mated with castrated males (receiving replacement testosterone) get the usual vaginal/ cervical stimulation, and hence undergo the hormonal changes (prolactin releases)
such females show all the concomitants of pregnancy for quite some time afterwards - their bodies appeared to be fooled into thinking that they are pregnant
induced ovulation
females of some species do not ovulate until mating occurs
such animals tend to be continually receptive or easily become receptive under the correct conditions
ie/ ovulation is stimulated when rats have their flanks stimulated
induced puberty
female shrews do not even go through puberty until their first copulation - no secretion of gonadotrops until first coapulation
they will go through puberty and get pregnant all in one fell swoop - quite economical
behavioural estrus
occurs when an animal has been exposed first to estrogen and then progesterone
periaqeductal gray
lesions greatly diminish lordosis
Human Ovarian cycle
- FSH stimulates maturation of follicle
- secretion of estrogen from maturing follicle causes LH secretion
- LH secretion causes ovulation, then causes ruptured follicle to be a corpus luteum
- corpus luteum secrete estrogen and progesterone, preparing uterus for pregnancy
- without fertilization production of sex hormones declines, and menstruation begins again
in rats the luteal phase has to be induced, in humans it is spontaneous
testosterone
drives most of male sexual behaviour
- males who fail to produce testosterone in puberty, do not show signs of sexual interest, additional testosterone also shows no effect
testosterone in a rat
castrated males stop ejaculating within weeks
castrates stop mounting
t is cleared within hours, yet caustration effects are slow, suggesting structural changes
replacement of missing T restores the copulatory behaviour pretty much immediately
this is an example of the activational effect of testosterone
permissive function of testosterone
the presence of testosterone in a male allows sexual behaviour but does not cause it
presence of testosterone changes sexual activity under the right circumstances
only a tiny amount of T is needed to maintain fully normal sexual behaviour. increasing it does not increase sexual behaviour or change it in any way
excess T produced by males underlies agression and territorial in rats. linear relationship between T and agression. but not in humans
duds and studs
duds make T, and giving them extra T does not turn them into studs
castrated male rats given replacement T are much the same, a tiny does of T restores the studs to their former studliness- and no amount of T will studlify a Dud
serotonin may be responsible for dudliness
kinsey report
first descriptive info
revelations about masturbation, homosexuality
first realization that humans are engaging in this
masters and johnson
studies the physiology and phenomenology of human copulation
among other things gave physiological evidence of female orgasm being very similar to the male orgasm.
for orgasm, men ejaculation, women coapulation
describes the physiological correlates of each phase in coapulation: increase excitement, plateau, orgasm and resolution
described huge variability in sexual positions among hums
INAH3 (3RD INTERSTITUAL NUCLEUS OF THE ANTERIOR HYPOTHALAMUS)
much larger in men than women
much larger in heterosexual men than in homosexual men
suprachiasmatic nucleus
involved in rhythms
differs between hetero and homo men
homosexual men have reported different light/dark levels
effects of sexual behaviour on CNS
castrates with T implant
copulators paired with female for 30 days
non coapulators - no access to femal
result: experience of having sex changed the brain.
- SNB diffs between groups
- must be due to behaviour, not hormone
gay man hand
index finger and ring finger same size
gay woman hand
ring finger bigger than index
fraternal birth order effect
carrying male uterus changes subsequent babies orientation
if you have three or more brothers (more likely to be gay), this increases with more older brothers
F-series prostaglandins
released as part to ovulation in goldfish
pheremone, attracts males to mate - highly adaptive for males to be sensitive to F prostaglandins
vomeronasal organ
have olfactory organs that sense pheromones
a secondary olfactory organ, air can be directed to it for direction of pheromones
fighting in male mice
controlled almost entirely from pheromones (urine)
directly controlled by olfactory cues - androgen metabolites in strange male’s urine provokes agression
this is an attempt by the resident male to limit mating in rivals
the bruce effect
pregnant female mice, of they detect a strange male’s scent, will spontaneously abort and resorb the fetuses
other species do this too
very adaptive - if the father is gone, the new male will not care for the pips, or may attack them
the female does not lose the protein, thus not too costly to resorb
menstrual synchrony
the mcclintock effect. What signal is being passed between women
women living together tend to menstruate at the same time. pheronomal?
some vestige of a hominid adaptation - perhaps an anti-predator strategy - likely predator can not eat all the babies, more probability of yours staying alive
prsumably mediated by pheromones - humans DO have a vomeronasal organ
simple exposure to sweat from another woman can produce synchronixation
andron
perfumes based on sex steroid fragments
parthenogenesis
asexual, virgin birth
in some species, there are only females and no exchange of gametes
offspring is essentially clones
evolution still occurs - beneficial mutations may arise spontaneously, and if they prolong the life of the animal, more offspring with that gene will be born
since each offspring a nearly 100% copy of the parent, the parent’s inclusive fitness should be very high
sexual reproduction
more common, yet only 50 percent transmission of genes to offspring, so how is inclusive fitness maximized?
gamete-swapping allows for rapid joining of beneficial mutations from 2 genetic lines - gives a sort of accelerated adaptation
- produce more successful offspring - we are products of many successful offspring
variable strategies
some species can switch between sexual and asexual reproduction in response to local environmental constraints - if only a few offspring will be able to survive, best that genes be swapped in hopes of getting good mutations
aphids - decide for asexual or sexual based on environment - for survival
hermaphroditism
make both types of gametes
true ones contain both male and female sex organs, make both sorts of gametes and reproduce sexually by swapping sperm with neighbours
sexual reproduction may have arisen from cheating in hermaphroditic systems
counter adaptation would be to picky about sperm, increasing fitness of offspring and not needing to invest showy ornaments, agression etc etc
serial hermaphrodites
make both types of gametes at different points in life - when they get older switch from ova to sperm
species that have the capability of switching sex when they get older
much more common for female to switch to male
larger males dominate a harem of smaller females
if the male is removed, largest female may rapidly begin to change into a male is she/he can sucessfully dominate the harem, inclusive fitness goes up
smaller females do not have this motive, because they will be unable to defeat invading males
monomorphic
males and females same
dimorphic
males and females different
polymorphic
pronounced and profound
competing goals
males typically make small cheap, motile sperm, and frequent mating without investment maximizes their inclusive fitness
females make few expensive ova (investing in quality), invest an enormous amount in gestation and perental care
females thus motivated to get their best quality sperm and wherever possible to get a direct investment by the father
parental investment
may be food collection, rearing, warding off predators etc
especially important in humans, and other species where offspring are helpless
may explain more or less absence of estrus and continual receptivity in human females - males don’t know when they are fertilizing an egg, so they have to stay around to be sure of breeding
promiscuity
both females have numerous mates
this allows for sperm competition (intense competition in a women’s genetal tract)
polygyny
multiple females
one male mating with numerous females
often in forms of harems
differs from promiscuity in that females do not have access to multiple males
sort of a compromise - male gets numerous matings, females get quality stock and a degree of paternal investment
very common i mammals, and in many human societies
polyandry
multiple males
one female, many males
males do not have access to other females
pretty uncommon strategy - because of nature of ova and sperm
where does it occur, you usually find the males less decorative than the females, smaller and provide more of the paternal care
females compete for males and abandon offsprig to males care
monogamy
one male, one female
more stable in species with very altrical young
considerable pressure to cheat, either for males to get additional matings or for females to select the best sperm
uncertainty of paternity - potent force, because males are making such a large investment
sexual differentiation
is the process by which a largely-undifferentiated embryo of a species turns into either a female or a male
begins before birth in mammal
sex determination
provided by the sex chromosomes
indifferent gonads
undifferentiated gonads of the early mammilian fetus, which will eventually develop into testes
resemble both
step one in sexual differentiation
Sry gene expression
occurs by embryonic week 7
Sry is part of the Y chromosome - responsible for development of the testes
codes for a hormone called Sry protein
therefore if a Y is present, this hormone is produced. if there is no Y, the default condition is no hormone (develops into ovary)
step two of sexual differentiation
in the embryo of humans and other species, the primordial gonad is undifferentiated or bipotential. that is, there is a general purpose gonad that is neither a testicle of ovary
if Sry protein is present after week 7 (humans), it will direct the primordial gonad to develop into a testes
if there is no Sry protein present, the primordial gonad will develop into an ovary. this is the basis of the statement that the default human is female - maleness is imposed upon a female template
testes begin to make testosterone immediately
ovaries in contrast, do not produce hormones at first
genital tubercle
in early fetus, a “bump” between the legs that develops into a clitoris or penis
step 3 of sexual differentiation
around week 10
fetus has both male and female system of ducts from gonads to outside world
mullerian system
sytem that provides the basis of a female reproductive tract
wolffian system
provides the basis of a male tract
if the testes develop during sexual differentiation
testes secrete testosterone and mullerian regression hormone (MRH)
MRH causes mullerian structures to deteriorate, and the wolffian system develops, under control of T
some peripheral tissue, especially epithelium, contains enzyme 5 alpha reductase - converts T to extra potent dihydrotestosterone (DHT)
prostate develops under T control
dihydrotestosterone (DHT)
masculinizes the external genitalia into penis, scrotum
if the ovaries develop during sexual differentiation
no T is present, no MRH is present and by default the wolffian system deteriorates
mullerian system develops into female internal structures
peripheral tissue develops into labia and clitoris
Srx
XX females, but one X also has Sry region tacked on
develop in XX with testes - male looking
produce nonfunctional sperm
turner’s syndrome
only one sex chromosome, an X ( can not have a single Y)
defaults to a famale
emphasized language skills
underdeveloped ovaries - no SRY gene available
congenital adrenal hyperplasia
adrenal produce too little cortisol, so pituitary secretes ton of ACTH
exposing female fetus to androgens, resulting in partial masculinations
adrenals enlarges and output of androstenedione is way up
intersex genitals result - can be corrected
may produce tomboy behaviour
intersex appearance (size between clitoris and penis)
will not effect males - already have enough testosterone
androgen insensitivity syndrome
XY’s who are insensitive to their own testoterone
caused by an androgen receptor gene mutation that makes tissue insensitive to T (cant respond to it)
they develop the default female body, including functioning clitoris
they make MRH, so they lack internal genitalia
hormone organization effect
early effects of hormones on the nervous system
permanent
hormone activation effect
effect of sex hormones in “switching on” behaviour in adults
transient
sensitive period in hormones
there is often a finite perinatal “window” during which time a hormone may exert its organizational effect
a post-natal sensitive period is more probable in altricial species than in pecocious species
early T
T imposes male patterns of behaviour on the female default
early exposure to T is critical for this ( in mammals)
defeminization
perinatal T treatment in females
decreased or abolished lordosis in adulthood
masculinization
perinatal treatment in either females or castrated males
adult T treatment
results in male copulatory behaviour - mounts, intromissions and ejactulations
demasculization
castration, especially if early in development results in diminished or absent male sexual behaviour
in the case of early castration, adult T replacement cannot reverse the effect
feminization
perinatal castration
adult treatment with estrogen and progesterone
results in normal lordosis in the castrated males
aromatase
enzyme that helps T to be converted to a significant extent in the brain, into estradiol
this then acts of estrogen receptors in the brain and produces a masculinization
alphafetoprotein
circulates in blood and sequesters estrogens - can’t reach the brain
does not affter T
aromatization hypothesis
in early castrates, treatment with DHT demasculinizes the brain and adult T cannot provoke copulation. DHT cannot be aromatized
if early castrates treated with EB instead, show normal copulatory responses to T in adulthood, despite micropenis (due to the lack of DHT in developent)
less true of primates
SNB and angogenital licking
mums lick this region of male pups more than female pups
anosmic mums, who can not differentiate males from females lick less
ventromedial hypothalamus
involved in sexual behaviours, eating and agression
contains estrogen and progesterone - sensitive neurons
crucial for lordosis - lesions abolish the response
estradiol implanted directly induce receptivity in females
