Lecture 10 - Human Evolutionary Ecology Flashcards
Is human behaviour determined by their genes?
No, human behaviour has some genetic basis but what we do isn’t determined by genes, but rather the interaction between genes and the environment.
Give an example of a genetically determined disease
Huntingdon’s Chorea is a genetically determined disease which has 100% penetrance if an individual has repeats longer than 40.
However the age of onset depends on the repeat length and there is massive variation. Therefore even here where genes result in disease there is a large environmental input.
What is the ‘Naturalistic Fallacy’?
‘What is natural is right or moral’, however in nature this is not the case. Genes are always interacting with the environment and therefore ‘IS does not equal OUGHT’.
What is found in nature is neither right nor wrong.
“This behaviour is natural; therefore, this behaviour is morally acceptable” or “This property is unnatural; therefore, this property is undesireable.” This mindset led to the development of eugenics and contributed to the Nazi horrors of WW2.
Explain Dethier’s ‘Hungry Fly’ experiment.
Dethier attempted to show genetic determinism. He was studying the nerve impulses associated with the proboscis extension reflex. He produced genetically identical flies in every way but there was still massive variance between individuals. Even at the molecular level there was variation due to expression noise. Therefore he could not show the presence of genetic determinism.
What is genetic determinism?
Genetic determinism is the belief that genes, along with environmental conditions, determine morphological and behavioral phenotypes. The term is sometimes mistakenly applied to the unscientific belief that genes determine, to the exclusion of environmental influence, how an organism turns out.
Natural selection is a combination of which two factors?
Survival and Sexual Selection
Natural selection is the gradual process by which biological traits become either more or less common in a population as a function of the effect of inherited traits on the differential reproductive success of organisms interacting with their environment.
Sexual selection is a mode of natural selection in which some individuals out-reproduce others of a population because they are better at securing mates.
‘…depends, not on a struggle for existence, but on a struggle between the males for possession of the females; the result is not death to the unsuccessful competitor, but few or no offspring.’
‘…when the males and females of any animal have the same general habits … but differ in structure, colour, or ornament, such differences have been mainly caused by sexual selection.’ - Darwin
Explain Courtiol et al’s findings in 2012 from their study of pre-industrial Finland.
Courtiol et al looked at a group of lutherans in pre-industrial Finland between 1760 and 1849. There were in depth records that allowed them to account for each persons birth, marriage history, children and death. Few people left the population and few joined so the group was strongly monogamous. They found that reproductive fitness varied enough to allow for selection, the number of children per marriage strongly influenced individual fitness. Traits that benefitted survival, for example, such as resistance to influenza, would have been selected for, and become more common in the population.
In depth: Courtiol and his collaborators looked at a population of Finns during the period 1760 to 1849. Thorough church records during this time allowed them to track each person from birth, through all marriages, to death, while noting all of their offspring along the way. Because the population was strongly monogamous, explained Stearns, researchers could confidently assign children to specific parents, and thus accurately estimate people’s reproductive success. The more variation in the number of offspring individuals leave to future generations, the more susceptible the population is to selective pressures, such as disease.
Sure enough, Courtiol and his co-authors found that reproductive fitness, or the total number of children each person had, varied enough to allow for selection. The researchers looked at four areas that could contribute to variation— whether the person survived to sexual maturity (age 15), whether he or she married, how many times, and the number of children per marriage—and calculated how much each of these factors influenced overall fitness.
Not surprisingly, the researchers found that the number of children per marriage strongly influenced individual fitness. In addition, they found that survival was an even more important factor, likely because the Finns had a high rate of infant and childhood mortality. Finally, the number of marriages tended to influence men’s fitness, but not women’s. Men who remarried often married a younger woman still capable of bearing children, thereby increasing their own potential number of offspring. Women who remarried, on the other hand, usually did so later in life, after their reproductive window had closed, said Courtiol.
The data suggest that the population may well have been evolving. Traits that benefitted survival, for example, such as resistance to influenza, would have been selected for, and become more common in the population. Courtiol and his collaborators did not measure any specific traits, however, and thus merely demonstrated the potential for selection to occur, not that it did.
Describe the two different strategies employed by coho salmon.
There are hook nose salmon which are migratory, hold territory and live for 3 years.
There are also jack salmon, these are sneakers, non-migratory and live for 2 years.
They have different but equal strategies, ESS
What is the grandmother effect?
Women with grandmothers still alive rather than dead have higher fitness
