Ehrlich and raven hypothesized that if a new defensive trait evolves in a single plant species (or if a new trait to counteract a plant's defenses evolves in an herbivore species) the appearance of that trait could result in a period of species diversification. their hypothesis is also referred to as the hypothesis.

Coevolution

Explanation:

Ehrlich and Raven observed butterfly species and their host plants. Plant species had adopted a series of defence mechanisms against butterflies. In response the butterflies also evolved new traits to avoid these defence mechanisms.

In this way both butterflies and plants influenced each other's traits and they co evolved. The coevolution can lead to accumulation of lot of different characteristics which can lead to formation of new species and species diversification. Formation of new species will be observed both in plants and butterflies.

increase soil erosion                                             reduce soil erosion

cattle grazing                                                         hydroseeding

deforestation                                                         contour plowing

                                                                                planting vegetation

plant roots basically hold the top soil

together and stop soil erosion because

in such situation top soil is not removed

during flood but cattle grazing causes

soil erosion because cattle consume the

grasses and herbs and top soil is exposed.

same situation occurs because of

deforestation, the trees and plants are cut

down to expose top soil which causes soil

erosion

answer biotechnology;