Question

Given the transition to online learning, you now have more time to study the spiders in your neighborhood. Using appropriate social distancing, you and your friends collect the following data on the average web height off the ground and prey size for three spider species: wolf spiders, grass spiders, and orb weaver spiders. From these data, what do you conclude about interspecific competition between these three spider species? - Wolfspider — Grass spider --- Orb weaver spider Proportion of population Proportion of population Height of webs Prey Size The wolf spiders have the largest carrying capacity Niche partitioning based on web height should allow the three spider species to coexist Competitive exclusion will cause the orb weaver spiders go extinct Niche partitioning based on prey size should allow the three spider species to coexist

Answer 1

Answer 1:

Given:



...... Wolf spider — Grass spider --- Orb weaver spider Proportion of population Proportion of population Height of webs Prey Size

We can observe that all the three species of spider make webs at equal height.

However, from the graph on right, it can observed that sizes of prey preferred overlap. Weaver spider prefers small sized prey, wolf spiders prefer moderate sized pretty whereas grass spiders prefer large sized prey.

All the three species should be able to co-exist because of niche partitioning on prey size.

Correct choice should be:

(d) Niche partitioning based on prey size should allow the spider species to coexist.

Answer 2:

Given that the two population have same values for growth rate, r, population size, N and carrying capacity, K. Therefore the inhibition effect of population 1 on population 2 will be equal to the inhibition effect of population 2 on population 1 ,i.e. a12=a21.

Hence, correct choice should be:

(C) a12 = a21