Evolution Of Herbivory And Its Influence On The Morphology Of Herbivores
The word herbivory refers to an organism which eats plants or alga. This essay will discuss the evolution of herbivory, the impact that herbivory has had on the morphology of herbivores, and on the morphology of the plants in question. Moreover, I will also discuss how herbivory has affected the world we currently live in in relation to nutrient cycling and plant abundance, or lack thereof.
Due to differences in diet, animals have adapted various digestive organs to accommodate their needs as well as form symbiotic relationships. Because plant cells are encapsulated by a cell wall made up of several structural carbohydrates, they are quite difficult for most vertebrates to metabolize. There are many vertebrates, particularly herbivores, that participate in mutualistic symbiosis with bacteria. These microorganisms help their host by digesting the cellulose in the plants, as extant vertebrates do not have the digestive enzymes for this process. Various adaptations can also be seen in the digestive tracts of herbivores, for example, the koala. Koalas have longer digestive tracts than other carnivores would have, as the larger surface area gives the Koala more time to process the fibrous eucalyptus and reabsorb as many nutrients as possible. The changes in digestive system of mammals have come about due to the evolution of herbivores and its diet.
Plants always appear at the bottom of a food chain or web and their profusion is under threat from herbivores, as herbivores can reduce the production rate of the primary producers. To battle this danger plants have evolved defence mechanisms against herbivores. Plants employ a variety of “direct defence” mechanisms such as chemical and structural adaptations. Such direct defence can be seen in the species taro (Colocasia) who have acquired idioblasts. These idioblasts contribute to piercing the herbivore so that plant toxins (e. g. terpenoids, phenolics and alkaloids) can easily enter the animal’s body and cause harm, deterring the animal from any further grazing. The evolution of herbivory has caused plants themselves to adapt at a cellular and molecular level in order to survive. From the perspective of plant reproduction and plant abundance, the evolution of herbivory has played a role in damaging ecosystems. As a knock-on effect, herbivory then slows down nutrient cycling. In an experiment carried out by Utah State University, ecologists showed how, in a period of five years, grasshoppers affected plants. The experiment discovered that the quality of the grasshopper litter sometimes sped up and sometimes slowed down the nutrient cycle depending on the quality of feeding the grasshopper had had that day. The evolution of herbivory has caused a natural depletion in the abundance of plant life directly by feeding, but also effects the nutrients which plants are capable of absorbing and reusing.
In conclusion, the evolution of herbivory has caused many changes not only in the herbivores themselves, but also in the plant life which they are consuming. Herbivores overtime have adapted their physical and chemical features, similar to plants. While this is mainly beneficial for the advancement of herbivores as a species, they are also doing damage to their food source by overeating and not providing them with enough nutrients.
