BIOLOGY 1M03 Chapter Notes - Chapter 52: Survivorship Curve, Net Reproduction Rate, Logistic Function

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grayworm664

15 May 2017

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A population is a group of individuals of the same species that live in the same area at the same time. In both ecology and evolutionary biology, populations are the basic units of analysis. Population ecology is the study of how and why number of individuals in a population changes over time. Number of individuals present in a population depend on four processes: birth, death, immigration and emigration. Populations grow due to births and immigration, which occurs when individuals enter a population by moving from another population. Populations decline due to deaths and emigration, which occurs when individuals leave a population to join another population. Demography is the study of factors that determine size and structure of populations through time. To made detailed predictions about future of a population, biologists must understand the makeup of the population in more detail.

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A population of 100 slugs randomly mates except for 18 selfbreeding individuals. The population has a gene for darkmottling colour, M, which produces dark individuals when ahomozygous MM condition exists, and green individuals when ahomozygous MâMâ condition exists. Heterozygotes are mottled. What is the proportion (genotypic frequency) of the dark, mottled,and green slugs in the succeeding generation of thispopulation? The initial allele frequency of M is 0.7 and ofM' is 0.3.

b) Not all populations experience equal amounts of geneticdrift or non-random mating. Evolutionary biologists use theeffective population size, N_e, to estimate the size ofan ideal population that would undergo the same amount ofgenetic drift or show effects of non-random mating as theactual population. Smaller populations have more drift. The value of N_e can be determined from:

N_e = 4 N_mN_f / N_m +N_f

Where N_m is the number of males in the actual population andN_f is the number of females.

If one population of elkhas 2 males and a harem of 6 females and another population in thesame

region has 1 male and 11females. Which population is more likely to experiencegenetic drift? Why?

(keywords to look up: Sewall Wright, effective population size, andFisherian ratio)

taupedog760

Q1. What are alleles?Different forms of the same gene.Different genes.The different characteristics of an organism.Genes found only in humans.Q2. If you add up the frequency of homozygotes + the frequency of heterozygotes for one gene (i.e. at one locus) in a population, what number do you get?Q3. People who are heterozygous for the sickle-cell allele:Are susceptible to malaria but not sickle-cell anemia.Are susceptible to sickle-cell anemia but not malaria.Are not susceptible to either sickle-cell anemia or malaria.Are susceptible to both sickle-cecell anemia and malaria.Q4. In the case study in this lab, which genotype is represented by "2pq" in the Hardy-Weinberg equation?Homozygous HbAHomozygous HbSHeterozygous HbA/HbSNo specific genotypeQ5. Suppose that, in an isolated village, the proportion of individuals that have sickle-cell anemia is 0.1 (or 1 of every 10 people). What proportion of the population should be sickle-cell carriers, according to Hardy-Weinberg expectations?Q6. When you simulated the elimination of malaria at the beginning of the lab, once the allele frequencies stabilized, what was the frequency of the HbA allele?Q7. When you investigated regional differences, what was the frequency (over many generations) of the HbS allele in the village in the "slightly wet" part of Africa?Q8. What is the number of deaths due to sickle-cell anemia in a region without mosquitoes expected to be?Very lowVery highModerateRelated to the frequency of malaria allelesQ9. As long as there are multiple alleles of a gene in a population, why will the frequencies of the alleles always change over time?Because natural selection changes all allele frequencies in populations over time.Because genetic drift causes random fluctuations of allele frequencies in populations.Because diseases will eliminate some of the alleles, generating fluctuations in their frequencies.Because allele frequencies fluctuate before the alleles eventually become fixed.Q10. Imagine a huge population with a gene that has ten functionally equivalent, neutral alleles. A small but genetically representative group of individuals from the big population is transported to an island, forming a small population. Which of the statements below best describes what will likely happen over time, and why?Because natural selection doesn't act on neutral alleles, the frequencies in the two populations should remain the same over time.Genetic drift will cause one allele to first become fixed in the island population, and later to become fixed in the original, large population.Genetic drift will result in the allele frequencies of the two populations diverging over time, with alleles being lost sooner in the island population.The allele frequencies of the two populations will change similarly due to a combination of genetic drift natural selection.

indigosnake469

1. Life expectancies differ across populations. Life expectancy at birth in the U.S. is currently around 78 years (76 for males; 81 for females). Consider a population in which life expectancy at birth is 50. Given what you know about life history theory, discuss how this population would differ from the U.S. across the following life history characteristics: age at first marriage, age at first reproduction, total fertility (number of children born per female), length of time spent in school, and money spent on education. Be sure to support your predictions using life history theory.

2. The following data on interbirth interval (time between births), child survivorship, and percent of children married were collected to evaluate reproductive decisions within a population. Assuming a woman of this population has a 20-year reproductive span (maximum time available from first to last birth), use these data to 1) calculate the maximum number of live births a woman could have, and 2) determine the number of births that will lead to the highest fitness (surviving children who marry) if we assume that all married children will have the same number of offspring. To receive credit, you must show your work. Lastly, what are the implications of your results?

% child %

IBI (months) Survivorship ever married

12	0.6	0.4
15	0.64	0.47
18	0.68	0.54
21	0.72	0.61
24	0.76	0.68
27	0.8	0.75
30	0.84	0.82
33	0.88	0.89
36	0.88	0.96
39	0.89	0.96
42	0.9	0.96
45	0.91	0.96
48	0.92	0.96
51	0.93	0.96
54	0.94	0.96
57	0.95	0.96
60	0.96	0.96

BIOLOGY 1M03 Chapter Notes - Chapter 52: Survivorship Curve, Net Reproduction Rate, Logistic Function

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