ANBI 411.3 Lecture Notes - Lecture 13: Gestation, Endorphins, Gamete
20 Jun 2018
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Lecture 13: Sexual behavior in domestic animals
Function of sexual behavior- ecological/biological perspective
- F (long term goal): Reproduction- the ultimate goal
oProduce offspring for the next generation
- F (short term): reproduction- the immediate goal?
oBonding, social
oGratification- highly motivated behavior
oHormones and reward systems- endorphins (positive homrones)
Phylogeny: how did it evolve?
- Sexual (involves two animals) vs. asexual (involves one animal) reproduction
- Advantage of sexual reproduction
oNew genetic variation in subsequent offspring
oWhen there are two we get genes from both parents so diversity
- Adaptability
oFitness for survival
oBad mutations lost, good mutations spread
oDisease resistance
oAdaptability to environmental change
Male and female roles:
- Cost/benefit
- Males and females
oCo-operate in reproduction
oNo shared genetic material between genders, except in offspring
- male cost= dominance is huge part of this, it plays a part even in domestic livestock,
dominant will mate more then submissive
- male benefit long term= he has the ability to spread his genetics everywhere
- males short term= mating= positive things
- Goals
oMaximize offspring reared
oMinimize investment time and energy
Sex and commitment- mammals
- Female investment: direct
oLarge gamete
oGestation
oLactation and care
oin most cases the female has the most direct involvement in this
oshe is the one involved in gestation
ousually involved in lactation and care
- male investment: indirect
osmall gametes
find more resources at oneclass.com
find more resources at oneclass.com
opaternity uncertain
oprovision of resources during courtship, gestation, or care of offspring
polygamous: they can have different mates
- female selects males based on:
ofitness and health traits
osymmetry: both sides of the animals is the same
ocoloration
oavailability: is he available for mating
- males compete for access and control
oif we have more then one male the dominant makes the most, the lower they
are in the ranking the less they get to mate
Causation: what happens?
oHormones
oFemale behavior
oMale behavior
- Hormones have important influence: affect targeted reproductive tissues and nervous
system
- Increase likelihood that behavior is performed given appropriate environment
- Considerable individual variation in hormone responses and behavior
- Hormones similar in males and females
oHypothalamus: GnRH
No direct influence on behavior- it effects what happens in the body
oPituitary: FSH, LH
oFemales seasonal, cyclic
Ovaries: estrogen, progesterone
Uterus: prostaglandin
oMales seasonal
Testes: testosterone
Female Sexual Behavior
oAttractively- pheromones
oProceptivity- male seeking
oReceptivity- standing, lordosis (they posture, stands with back arched)
-Attractively:
oFemale becomes more attractive to the male while in estrus (a function of being
in estrus)
oThis could be due to pheromones in urine or due to behaviors during this time
oCattle and dogs have shown signs of pheromones
-Proceptivity:
oInitial phase when courtship occurs
oExample: cows
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
F (long term goal): reproduction- the ultimate goal: produce offspring for the next generation. F (short term): reproduction- the immediate goal: bonding, social, gratification- highly motivated behavior, hormones and reward systems- endorphins (positive homrones) Sexual (involves two animals) vs. asexual (involves one animal) reproduction. Advantage of sexual reproduction: new genetic variation in subsequent offspring, when there are two we get genes from both parents so diversity. Adaptability: fitness for survival, bad mutations lost, good mutations spread, disease resistance, adaptability to environmental change. Males and females: co-operate in reproduction, no shared genetic material between genders, except in offspring. Male cost= dominance is huge part of this, it plays a part even in domestic livestock, dominant will mate more then submissive. Male benefit long term= he has the ability to spread his genetics everywhere. Goals: maximize offspring reared, minimize investment time and energy.
