Question

Which of the following statements about speciation is true?

Select one:

a. Wind-pollinated plants typically have higher speciation rates than animal-pollinated plants.

b. Species that disperse widely have higher rates of speciation than those with limited dispersal.

c. Sexual selection seems to decrease speciation rates.

d. Herbivorous insects typically have higher rates of speciation compared with insects that prey on other insects.

e. Dimorphic birds have lower rates of speciation than monomorphic birds.

Answer 1

Answer is B. Species that disperse widely

Explanation:

Speciation Rate is two type: 1> Punctuated Equilibrium : A new species diverges rapidly from the parent species. Factors: small population, rapid environmental changes

1> Gradualism : species diverges slowly. Factors: Large population; stable environment.

A> Wrong; Pollen are taken by wind to long distance with no selection or favoritism. While animal-pollinated plants have specific selection and favoritism due to different species (pollinating agent) and birds. So, divergence in species is more prone in second case.

B> Right: Dispersed species have larger area to interact with environment, geographical changes are seen more in larger area which can become biological barrier to dispersed species resulting more speciation.

C,E> Wrong: Sexual selection in theory seems to support speciation rate but it has one disadvantage : that is all mates (male and female) live in same space. This give a chance to interact further, living small room for divergence. C and E option-similar.

D> Wrong : In food chain herbivorous are at bottom, therefore they have large and stable population favoring Gradualism. Vice -versa for insect eating insects.

Summary: For higher speciation, there is need of barrier of any kind which is more in dispersed species.