Name_______________________________ Biology 44- 11 am 1st hour test, Feb 14, 2011Each question is worth 5 points.1. You find a population where 19% of the individuals exhibit a dominant phenotype. If the population behaves according to Hardy-Weinberg predictions, what percentage of individuals would you expect to be heterozygous? Show calculations P² + 2pq = 19; q² = .81, q = .9, p = .1 // 2pq = .182. If, over several generations, the dominant allele changes in frequency from 19% to 50%, do we know that it was selected for? Why or why not? Under what circumstances?? No – genetic drift or immigration could have caused the shift, but only in a small population.3, According to Guthrie, evolution causes species not to get better through time, just older. Explain what is meant by this. As a species evolves, its competition, diseases and predators also evolve (the environment changes) So the species may not be better adapted – only older = still alive.4. What were the main factors leading to the change in birth rate (demographic revolution) in what are now the developed countries (Europe and U.S.) Movement rural to urban, and more women educated and working.5. What factors or conditions exist when the number of species in an area is constant (at a maximum)? Most people answered as if the question asked conditions when the numbers of a species remain constant. It didn’t. the question asked the total number of species remains constant = which is when extinction of species = colonization in an area (MacArthur- Wilson equilibrium)6.. What is good and what is bad about a species being a ‘specialist,’ for instance in food requirements. Specialists cant be outcompeted for their resources, but their resources (like food) are limited in variety, and if these resources fail, the specialist goes extinct – cannot adapt quickly – has low variation. .7. What is meant by the term allopatric speciation and what are its essential requirements? Means speciation involving isolation of two populations. They must stay isolated for a long period of time (no genetic interchange) long time required to make gene pools different.8. What factors make speciation through polyploidy more possible in plants than in animals?. Plants can self fertilize, plants can tolerate polyploidy, and the new plant can survive in its environment ( plants simpler in genetic makeup and ecology)9. In zoogeography, what is a ‘filter’ bridge and how does it work? A filter bridge is a land connection which, due to climate or ecology, only certain species can reach – example is a cold bridge or a forest bridge, accessible only to species that can live in theseconditions10. How do we think conditions were different from today when life first arose on earth? Why do we think so? Main one was no oxygen – shown by reduced compounds in rocks , lack of oxygen in many starspectra, belief that life was necessary to cause free oxygen to form, and that organic molecules can not exist and accumulate over time in presence of oxygen..11. Why did Darwin accept the idea of Inheritance of Acquired characteristic as part of his theory of evolution? Darwin needed an explanation for the reappearance of variation – knew no genetics so accepted this theory as a possibility12. It has been stated that people who fail to finish high school are more fit than college graduates. What is the basis of this statement and what is necessary for fitness to apply here? Bad question. What I wanted to ask was does this cause humans to become less fit?? While it is true that those who fail to finish high school have more children, this may not have any effect on overall human fitness. The reason to not finish high school may be due to economic and social causes, not to genes. 13. A high percentage of the population is overweight and being overweight is harmful (decreases life expectancy). Present some explanations for why natural selection has failed to eliminate such aharmful trait. Weight not much under genetic influence; overweight may reproduce before death, and in the past, overeating may have been selected for (Australopithecus scavengers)14. An island has many more species on it that you would expect, given its size. Present two possible explanations for this. Island has recently gotten smaller, island is close to mainland or recently connected to mainland. Island is tropical and compared to temperate islands15. What is the geological idea of ‘uniformitarianism?’ Is it correct?Only those processes we see on earth today are necessary to explain past geologic events. It is notcompletely true as there have been large magnitude events in the past (meteors) but it is more true than catastrophism, which implies universal events affecting the whole earth.16. Living fossils are organisms very similar to those that lived millions of years ago. If you were looking for such a species, under what conditions would you expect to find them? Where would you look? Why? Need a place with no competition, and very stable – perhaps an isolated oceanic island.17. What are the characteristics of an ‘r’ species?Small size, short life, lots of young and fluctuating in numbers18. Why do we consider Pekinese and Great Danes (dog breeds) the same species when it is physically impossible for them to mate?? (what is the definition of a species?) Although they cannot mate, they can ‘potentially’ exchange genetic information = mate with intermediate sized dogs and pass genes between each other - this is what keeps their DNA so similar.19. Can evolution occur without natural selection?? Explain. Genetic drift can change gene frequencies without selection through time.20. Can a species change in appearance without the occurrence of new mutations?? ExplainYes – all species contain lots of allelic variation. The experiment when you select for a trait in a population (large size, high defecation rate, etc.) is selecting for alleles already in the