Question

A long answer question will require one to three paragraphs to answer.

1. Compare and contrast r and K-selected life history strategies. How do the two strategies differ in regards to stability of the environment, organism size, energy invested in offspring, number of offspring produced, life expectancy, and number of reproductive events? Which survivorship curve depicts r and K-selected organisms?

Answer 1

ANSWER : Comparing and contrasting the r and k-selected life history strategy-

1. DEFINITION:

Both the terms r-selection and k-selection are used to describe the growth and reproduction strategies of various organisms to trade off between the quantity and quality of the offspring.

2. STABILITY OF ENVIRONMENT:

- The r-selection generally occurs in unstable and unfavorable environments which is interfered with ecological disruptions. The resources used here is mainly for increasing the rate of reproduction.

The k- selection generally dominates during stable and favorable environmental conditions . The resources are generally used to enhance the survival rate of individuals.

3. ORGANISM SIZE :

-The body size / organism size of those who are r-strategist is typically smaller and attains  very early onset of reproductive maturity / sexual maturity.

-The body size /organism size of those who are k-strategist is typically large and huge and they have late onset of reaching reproductive maturity/sexual maturity.

4. ENERGY INVESTED IN OFFSPRING & NUMBER OF OFFSPRING PRODUCED:

- The r-strategist generally produces many offspring per brood or per reproductive cycle , which require investing a very little amount of energy and parental care towards them. This may contribute to higher mortality rate in them.

- The k-strategist produces very few number of offspring per brood or per reproductive cycle , which require higher energy and parental care towards them. This ensures lower mortality rate.

5. LIFE EXPECTANCY:

-The r-selected species generally have low survivability but high growth rate.

- The k-selected species generally have high chances of survivability but lower growth rate.

6. SURVIVORSHIP CURVES :

- The r-strategist generally exhibit the Type-III survivorship curve which represent high death rate or low survivorship rate.This is generally the characteristic of small mammals, fishes and few invertebrates.

- The k-strategist generally exhibit the Type- I survivorship curve which represent low death rate and high survivorship rate). This is generally the characteristic of large mammals , with larger body size.