BIO120H1 Chapter Notes -Red Queen Hypothesis, California Condor, Achillea Millefolium

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14 May 2012

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Barrett ricklef chapter notes (examples related to materials on lecture) With cyanide fumigation, gene for cyanide resistance = higher fitness increase in #s pg119-120, field cricket in hawaii, field cricket coexisted with parasitoid fly. Parasitoid fly home in on the cricket;s mating call to locate hosts female flies lay their eggs in the cricket and the cricket is eaten from the inside out by the developing fly larvae. Makes different nest during different time period to help chicks stay cool: Early spring (cool weather): entrance face away from direction of the cold winds. Hot summer: entrance face prevailing afternoon breezes (circulate air through nest to facilitate heat loss. Example of more general ability of the phenotype to respond to variation in environment (phenotype plasticity) Larvae from alaskan grew more rapidly than those from michigan populations at low temperature. Larvae from michigan grew more rapidly than those from alaskan populations at high temperature.

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For many years, antibiotics have been effectively used to treatbacterial disease; and pesticides have been used to protect ouragricultural crops from many kinds of pests, including insects,worms (nematodes), fungi, or agricultural weeds, for example.

A growing concern for treating bacterial diseases or pest outbreaksis the evolution of antibiotic or pesticide resistance by bacterialor pest populations. Resistance means that a particular antibioticis no longer effective in treating a disease, or that a particularpesticide will no longer prevent crop damage. This resistance canbe viewed as evolution of a new trait at the population level,which is resistance to an antibiotic or to a pesticide. In thisassignment, you will explore specific examples of antibiotic orpesticide resistance.

Assignment details:

After reading materials about evolution and about antibiotic andpesticide resistance in the text, the Course Materials, the AIUOnline Library and / or the Internet, answer the following.

1.Select and describe one example of antibiotic resistance orpesticide resistance. Be specific in your choice.

â¦Describe the background for your choice of resistance. Includedetails about the disease or pest and the established controlstrategies. How have we used antibiotics (to treat a particulardisease), or pesticides (to protect from a pest); and how has thischanged?

2.Explain how the resistant trait evolved based on principles ofnatural selection and evolution of a trait at the populationlevel.

3.For your specific example, what are the consequences ofresistance in terms of human health or crop loss / damage?

4.What steps can be taken to prevent or slow down the evolution ofantibiotic or pesticide resistance? Do you think we will succeed indoing so? Why or why not?

viridiancricket950

For 15 years, beginning in the early 1970âs, Norway rat populations were controlled throughout the United States and England using the rodenticide warfarin. However, resistance quickly developed and was linked to the dominant allele designated R. Unexposed populations carried predominately the susceptible allele (S). In rural England the genotypic frequencies (RR, RS and SS ) in unexposed rat populations were 0.18, 0.49 and 0.33, respectively. In one sample of a 60 km2 area of rural England where the rodenticide had been applied the genotypes RR, RS and SS were found at frequencies of 0.085, 0.627 and 0.287 respectively. What is the fitness of each of these genotypes? What equilibrium allelic frequencies would you expect if warfarin use had been continued?

whitemallard400

Consider two populations of guppies living in a tropical stream. One is upstream of a waterfall, and the other is downstream. In both populations, homozygous individuals have either blue or red stripes, depending on the allele they carry: R for the red allele and B for the blue. RB heterozygotes have purple stripes.

In the downstream population only, there are crayfish that feed on the guppies. Because the crayfish can't see red colors, the red-striped guppies have higher fitness than blue or purple. Comparison to the upstream population, where there are no crayfish, indicates that the selection coefficient on purple and blue guppies is 0.25.

The current frequency of the R allele is 0.64. Your job is to calculate the percent change in allele frequency that occurs in the next generation due to crayfish predation. To do this you should:

a) Use the Hardy-Weinberg principle to determine expected genotype frequencies in the generation without selection

b) Determine the relative fitness of each genotype

c) Calculate the genotype frequencies in the new population following selection.

d) Find the percent change in allele frequency of the resistant R allele.

cerisesquirrel57

BIO120H1 Chapter Notes -Red Queen Hypothesis, California Condor, Achillea Millefolium

BIO120H1 Full Course Notes

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