PSYO 2160 Lecture Notes - Lecture 12: Population Genetics, Mate Choice, Egg Cell
9 May 2018
School
Department
Course
Professor
Sexual Selection
Sexual Selection
o Define sexual selection that has to do with the mating pair
o Competition and choice for a mate
o More and more research supporting that human mate choice is not random
o We evaluate our potential mates - however we are constantly evaluating them
such as quality of the endocrine and immune system
o We look for very specific characteristics
The Original View: Darwin
o In mammals, everything occurs inside the female until birth. We are stuck with the entire
process so she has to make a good choice in the male that will impregnate her
o Females have a lot to lose and that is why female mammals are picky. This is good!
o They have limited amount of ova, which isn't really a concern in humans. However,
you cannot afford to just waste them
o Age limitation
o Child bearing is extremely costly as well - lactation and energy
o Males actually may be aware of this, they will in participate in taking care of the young
because they realize the cost and constraint it puts on females
Intra Sexual Selection
o Within a sex
o Ex. Lions, there is a pride take over where there is a dominant group of males and one
dominant individual. When a stray male wants to take over a pride, they will fight the
dominant males and kill their young and immediately start impregnating the females
o The old cubs are not their genes and thus not theirs so they can start anew
o Ex. Wolves, wolves have an alpha male but there is also an alpha female that is equally
important. Males will determine their own dominance hierarchy, but so does the female. By
default the two alpha's mate because they were determined to have the best genes.
o Indication of overall fittness
o Pheremones - part of your olfactory bulb, more specifically the VMO (vomeronasal organ)
o Ex. The lining up of menstrual cycles of women who live in close quarters
Male-male competition
o Most explicitly is aggression
o Kleptogamy, where males that won't have the chance to mate, steals a female
In Other Words
o Genes work as a form of currency, this is why animals don't waste their gametes which is
why there is a lot of time put into finding a mate
Ecological Factors: The R and K Species
o Kind of like the differentiation between specialist and generalists, it can be very specific.
Animals that are in the same genus may be different
o K - kool, kalm
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o Small litters, they can't reproduce often
o They go for quality over quantity, meaning that they will be much more picky in
choosing their mates
o If they become dangered or threatened, it is dangerous because you don't have the
same offspring output as an r species
o R- rushed
o Shotgun approach
o Their main goal is to produce as many offspring as possible
Note:
o Many species will lie in between
Basic Assumptions
o Identification of good genes, the connection between phenotype and genotype
o For humans, visual cues are extremely important, the same as in birds
o For birds, the males have the colourful impressive plumage
o For humans, we have face symmetry for example
o The association to be there for this explanation, if you were challenged
immunely in development your face will be more asymmetric. SO thing's aren't
perfect
o Side note - apparently, Angelina Jolie and Brad Pitt have very symmetric faces
o Turns out wolves are incestual - a mother was studied who mated with her son
o There is a mechanism, that if you are going to inbreed, you breed with the best genes,
which explains why the mother and son mated
o Remember, that the wolves social structure was that they have a dominant male and a
dominant female in the hierarchy
o Inbreeding affects some species more than others
The Conflicts
o Crocodiles are the only reptiles where there is some father care
o Epigametic are the things that animals will judge in order to determine good genes
o Ex. Tail of a peacock - this is an expression of their genes
True for all mating systems?
o Mainland Moose- almost fully disseminated and the males have nubby antlers
o Monogamous species are different
o Humans are monogamous and that is not common for great apes. Gibbons are the
only other primates that are monogamous.
Monomorphism in Primates (get Jeremy's notes for this slide)
o Mating systems are the way organisms organize their ways of mating
o In some species, there are more distinct patterns than others
o Ex. Humans are commonly monogamous (monogamy)
o Polygamy - there are multiple types but these two are more important
o Polygyny - this is where one male gets access to multiple females
o Polyandry - this is where one female has control and access to multiple males
o Keep in mind, all of these polygamous mating systems are existent in humans
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
In mammals, everything occurs inside the female until birth. We are stuck with the entire process so she has to make a good choice in the male that will impregnate her: females have a lot to lose and that is why female mammals are picky. This is good: they have limited amount of ova, which isn"t really a concern in humans. Intra sexual selection: within a sex, ex. Lions, there is a pride take over where there is a dominant group of males and one dominant individual. Wolves, wolves have an alpha male but there is also an alpha female that is equally important. Males will determine their own dominance hierarchy, but so does the female. By default the two alpha"s mate because they were determined to have the best genes. Indication of overall fittness: pheremones - part of your olfactory bulb, more specifically the vmo (vomeronasal organ, ex.
