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Evolution.docx

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Department
Psychology
Course
PSYCH 1X03
Professor
Joe Kim
Semester
Winter

Description
Evolution: - Module 1: Introduction o The biological sciences have a shared agenda – their goal is to elucidate the adaptive deign of living things. - Module 2: Adaptations o Adaptations  Are biological traits that help an individual survive and reproduce in its habitat  Adaptions perform a specific function – they are always “for” something that make and organism better suited to its environment.  The adaptions serve identifiable functions in the life of the individual e.g. they might enable organism to interact with a complex physical environment.  E.g. eyes enable you to respond effectively to things around you be detecting and analyzing the reflected light. Racoons have goods night vision but their front paws have adapted to be so sensitive they can practically see through them, bats have adapted to have echo location.  Perceptual processes and behaviours are also biological adaptations. To understand complex process (e.g. how to you see), scientists break these problems in to sub-tasks: how do you detect edges, how do you assess the speed of an object or perceive a threat? Once these critical steps have been identified, you can look for processes that are capable of accomplishing those tasks, in other words you can look for the relevant adaptations.  Adaptationists are scientists who use hypothesis about adaptive function to guide their analyses.  Higher mental processes (selective attention, memory encoding, memory retrieval, word recognition) refer to tasks that the min needs to accomplish to do its job. They refer to the adaptive functions of mental activity - Module 3: Evolution by Natural Selection o Adaptations emerge in development as a result of the activation of relevant genes in interaction with relevant aspects of the environment. o Natural Selection  Differential survival and reproduction of organism as a result of the heritable differences between them.  Individual differences o Within any population, there is variation among individuals for any given characteristic.  Differential Reproduction: o The individual differences affect individual’s chances of surviving and reproducing. o Some individuals will have more offspring than others.  Heritable o The offspring of any successful reproducers will resemble their parent with respect to these variable characteristics.  How adaptations arise and become differentiated in related species  How adaptations maintain their complex functionality in spite of the destructive force of random genetic mutations.  Discovered by Charles Darwin and Alfred Russel Wallace  Is one of the 4 basic mechanisms of evolution, others being mutation, genetic drift an migration  E.g. blue fish better able to catalogue in Blue Ocean than red fish which are much more visible to predators. Therefore the red fish get eaten more often and so on average, the blue fish survive and produce better than the red fish. Blue fish tend to have blue coloured offspring because body colour is a heritable trait.  Over successive generations, there will be a selective transmission of heritable parental traits and the population will be mostly blue. This is because the specific characteristics that are best adapted for survival and reproduction are going to be reproduced at higher rates. Eventually whole population will be blue. - Module 4: Natural Selection in the Wild o Stabilizing Selection:  Selection against any sort of departure from the species-typical adaptive design. E.g. fish would remain blue over time. However is there has been a significant change in the environment, and then selection favours traits that are not typical – i.e. evolutionary change can be observed. o Classic example of rapid evolutionary change comes from work on beak shape and size of Medium Ground Galapagos finches (by Peter and Rosemary Grant)  In 1977, severe drought hit island and decimated vegetation. Food was scarce and all small seeds eaten rapidly leaving only large tough seeds not usually eater. Birds that had unusually big heavy beaks were able to eat large seeds and survive whereas small beak birds died of starvation. Avg. beak depth increased from 9.4 to 10.2 mm. Offspring had larger beak size as well.  Changes are usually small can be reversed, e.g. when drought ended and small seeds were abundant again, average depth of finch beaks returned to pre- drought size.  Changes brought through natural selection are more permanent and form a potential foundation for diversification of related species. - Module 5: Reproductive Success = Fitness o Natural Selection favours those who are best at reproducing o Darwinian Fitness-Average reproductive success of a genotype relative to alternative genotypes. So can be:  Evolution- change in gene frequency over generations - Module 6: Sexual Selection o In sexually reproducing organisms there is often competition for mates and natural selection acts on mate finding and reproductive behaviors.  E.g. Peacock’s tail:  Energetically expensive to produce  More conspicuous to predators – interferes w/ ability to get away  Harder to get away from predators  Increases risk of dying (is no help to survival – in fact usually shed tail after breeding season)  However does contribute to fitness via increased change of mating  Sexual Selection:  The component of natural selection that acts on traits that influences an organism ability to mate.  Even if some evolved traits elevate mortality and are actually selected against in that context, they can still evolve and become more elaborate under the countervailing pressure of sexual selection i.e. female mating preferences  Elk compete for dominance status – the one who wins will get to monopolize a harem of females  Stags are more vulnerable than females o Because of bulk, males are heavier and have less stamina to run away from predators and get stuck in snow o So overall effect on survival is negative o Stags shed antlers after then end of breeding season  Sexually Selected Traits  Both trials have negative effect on survival  For the elk: antlers are used in combat therefore selective force is success in combat o Evidence that females do not care about size or shape of antlers  For the peacock: tail-feathers are used in courtship for females therefore selective force is Female Choice  The component of natural selection (the differential reproduction of types0 that results from differential access to mates:  Being chose by the opposite sex  Defeating same-se rivals in mating competition  If an anatomical trait differs between the sexes or if a sex difference only exists in the breeding season or is exaggerated then that’s a hint that it may be a sexually selected trait  It has been shown that females discriminate between males on basis of the numbers of eyespots – more is better, even 1-2% more – and they also prefer males with good left-right symmetry.  Female choice picks out males with best resistant to local diseases  Wants father that gives best genes for being healthy  Perhaps In humans: breasts, deepening of male voice, subtle differences in facial structures - Module 7: Species-Typical Behaviour & the Comparative Approach o Every animal species has its own characteristic behaviour.  Behaviour is an evolved characteristic that gives species specific adaptations  We can study behavior like we study other adaptations: we can test hypothesis about its adaptive functions-about what it’s good for- and its evolution o Three species of sandpipers –can be differentiated by behaviour, vocalizations, and dietary ad habitat preferences. E.g. sanderlings like sandy beaches whereas the other species like muddier shores. But all have signature way of foraging.  Sanderlings – little flocks of sanderlings race out after receding waves and furiously peck at insects on wet sand and then race back towards shore in front of the next wave  Semipalmated  Dunlin o Species Typlical Behaviour  Physical Form (topography)  Habitat preference  Group Size (flock vs. sole)  Social System  How old are kids when head out  Di animal continue to recognize and interact with each other o Behaviour Genetics – Selection experiments – selectively breed those who are most or least aggressive or whatever trait you like and you can change the animal’s typical behaviour  E.g. dogs have many purposes  Drosophila has small lifespan so I good to use for model system for experiments - Module 1: Introduction to Social Behaviours o There are many examples in humans and animals where individuals appear to behave altruistically; helping others at a cost to themselves  Bees  Belding’s ground squirrels (whistle blower raises alert of predator)  Humans o Evolution acts at the level of genes and those genes that contribute to an individual’s fitness will consequently get replicated more often, increasing in frequency in successive generations. This concept is sometimes referred as the ‘selfish gene.’ Natural Selection will favour genes and gene complexes that best serve their own interest, namely replication. o o Increasing the fitness of others can sometimes improve your own fitness prospects   E.g. Imagine on Hockey team with only 6 players w/ bad player Billy. You need minimum 6 players so can’t send Billy off ice. You can invest time and resources required to teach Billy to play better. On surface looks like unselfish extra work
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