Question

6. All living organisms on earth need energy to grow, reproduce, and carry out cellular functions; however, these energy requirements are not equal for all cells. Neither are they equal for different species. (a) Discuss the biological evidence that shows that larger animals require a lower metabolic rate than smaller animals. (b) Discuss the effect of energy on reproduction for K-strategists and R-strategists.

Write your response below.

Answer 1

Answer - (b)

➡ The Life history strategies concept of r and k -selection was initially given by Arther and Willson and it is modified by Pianka .

Case 1 ÷

➡ In uncrowded , resource rich environment , natural selection favours individuals which are able to achieve rapid population growth such population are called as r-stratigst (,r means birth rate).

➡ r - strategists population has high reproduction output and lower competitive ability so they require less energy than k-stratigists.

➡ At low population density and high resource availability , it has higher growth rate as compared to k - strategist .

➡ r-stratigist population remains on ascending part of logistic growth curve .

Examples of r-stratigist are pioneer and early serel stages of succession .

Case 2 ÷

➡ In crowded and resource limiting environment natural selection favours organism which are competitive due to proper niche seggregation I or nieche seggregation .

➡ At high population density and resource availability k- strategists have higher growth rate and they require high energy for their reproduction than r-stratigist .

➡ k-stratigists has low reproduction output and high competitive ability and thus require high energy than r-stratigists that's why population is maintained at upper asymptote of logistic growth curve where,

N = K

i.e, Number of individual or population size is equals to carrying capacity .