Population sample Mean- 20.5 mm 25 2. A biologist is studying a large laboratory
ID: 256705 • Letter: P
Question
Population sample Mean- 20.5 mm 25 2. A biologist is studying a large laboratory population of house crickets that shows considerable variation in body size; in a random sample of 100 individuals, mean body length was 20.5mm but ranged from 16-27mm (see top figure at right). (n - 100) 15 10 A. What aspects of the figure at top right suggest that body length in crickets is a quantitative trair? Briefly explain. ( point) 16 18 2022 24 2283 Selected adults (shaded) Mean - 23.0mm (n 20) -20 15 10 B. What are the two general sources of variation that likely account for the variation in body length in this laboratory population? Briefly explain? (1 point 16 18 222 24 2628 30 Offspring of selected adults (n 100) Mean 22.2 mm2s C. In order to estimate the heritability of body length, the biologist performs an artificial selection experiment. She selects the 24 largest crickets (12 males and 12 females) from her sample and calculates their mean body length, 23.0mm (shaded bars in the middle figure at right). She then allows these 24 largest crickets to breed with each other, and raises their offspring until they are fully grown. In a random sample of 100 of the grown offspring, mean body length was 22.2mm but varied from 17-29mm (see bottom figure at right). From these results, calculate the selection differential, the response to selection, and the estimated realized heritability of body length. Be sure to show your work. (3 points) 18 20 22 24228 Body Length (mm) Selection differential: Response to selection Realized heritability: D. The estimate of realized heritability in (C) is based on an artificial selection experiment in a laboratory population maintained under fairly uniform lab conditions. Now imagine that the biologist studies a wild population of crickets and estimates heritability of body length from parent-offspring regression under tield conditions. Would you expect her estimate of heritability from this wild population to be greater than. than, or about the same as the estimate in (C)? Briefly explain. 2 points) naturalExplanation / Answer
Answer A: Quqntitative trait is a trait of measureable phenotypes that are controlled by more than one genes and environment. It can greatly vary among individuals over a range and different environment and forms a continuous distribution. The given data of body length of house crickets shows a continuous distribution from 16 mm to 27mm among 100 random individuals. As it forms a large variation of the data and a continuous range of distribution of the phenotype, it can not be measured by ratios or counts. Thus we can conclude that it is an quantitaive trait.
Answer 2: The two general sources of variation that are account for variation in the body length phenotype are (a) genetic variation and (b) environmental factors.
Answer 3: Selection differential = Mean body length of selected individuals (23 mm) - Mean body length of the population (20.5 mm) = 2.5 mm
Realized heretability = (mean of original population - mean of responded popultion) / (mean of original population - mean of selected population) = (20.5 - 22.2) / (20.5 - 23.0) = - 1.7 / - 2.5 = 0.68
Response to selection = realized heretability x selection coefficient = 0.68 x 2.5 = 1.7 or mean of responded popultion - mean of original population = 22.2 - 20.5 = 1.7
Answer 4: Heretability estimate from wild population to be greater than as estimate in laboratory condition because the two general sources of variation i.e genetic variation and environmental factors both are applicable in wild condition whereas in lab condition environmental factors are almost same.