Lecture 3 - Sneaky Sex Flashcards
What is a “mating system”?
A mating system is the social organisation used by a species to maximise reproductive output
What is a ‘solitary’ mating system?
Individuals seek out mates during the breeding season, otherwise little interaction occurs. E.g. pumas, tigers, bears, koalas, orangutans
What is a ‘monogamous’ mating system?
A male and female pair to the exclusion of all other mates for a lengthy part of their life to raise young e.g. penguins, wild cats
What is a ‘polygamous’ (promiscuous) mating system?
One member of one sex mates with many of the opposite sex e.g. MANY animals
What are the different subcategories of polygamous mating systems? Quick description of each too.
Polygynous: one male to many females e.g. lions
Harem mating: one male has a harem of females e.g. gorillas
Polyandrous: one female to any males e.g. some turtles
Co-operative breeding: group of males and females associate together but only a select few breed e.g. meerkats
Comment on humans mating system.
- Known to be ‘serial monogamists’.
- Humans opt for polygynous relationships when times are tougher. If not, monogynous relationships are preferred
How to animals signal that they are ‘available’?
- Olfactory signals
- Visual signals (males often v colourful) - relies on testosterone & production of carotenoids
- Raised circulating testosterone in males and oestrogens in females induces species-specific secondary sexual characteristics used in signalling for mates.
What is the “immunocompetence handicap”?
- Colourful animals or those with large signallers (eg horns or antlers) are more exposed to predators and frequently have more parasites
- Effects cytokine expression (important in the first wave of the immune response)
What are pheromones?
Chemicals that produce a behavioural or physiological response in an organism. Can rely on sex steroids and complex proteins excreted in the sweat, faeces and urine
Why does female urine smell sweeter in the follicular stage?
Estradiol and estrone are converted in the liver to estriol, which is excreted in the urine and faeces conjugated with sulfuric acid.
What happens to testosterone in the male’s liver and when he is trying to signal availability?
Testosterone is converted in the liver to the
17-ketosteroids - Androstendione, Dehydroenpiandrosterone (DHEA) and Estrone.
These are excreted in the urine and faeces conjugated with sulfuric acid or glucaronic acid.
What is a ‘latrine’?
Known sites where all individuals in an area will pass at different times.
What are some signals that humans give off to signal their availability?
- Chemosignalling
- Apocrine secretions which produce pheromones (sweat, skin, hair)
- Pheromones change with stress
- People pick their mates on the basis of dissimilar HLA antigens (human leukocyte antigen - the human version of the major histocompatibility complex)
What are some scientific reasons for infidelity?
- Hormonal influences on behaviour during the menstrual cycle
- Risk taking behaviour during ovulation
- Suspected infertility of the male
Why were hyenas thought to be hermaphrodites?
- In females the labia are fused to form a pseudoscrotum and the clitoris is enlarged to form a male-like phallus through which the urogenital sinus traverse
- Females are larger than males
- Low aromatase therefore more high circulating androgens “girls pretending to be boys”
