Coevolution With Particular Reference to Herbivory Essay

2230 Words9 Pages
COEVOLUTION WITH PARTICULAR REFERENCE TO HERBIVORY Of all the extant organisms in the world, it is believed that terrestrial plants and their natural ‘enemies’ constitute more than forty percent. Moreover, plants exhibit a remarkable diversity of supposedly defensive characteristics including trichomes, spines, silica, secondary chemical compounds, temporal avoidance of enemies, and structures along with chemicals that attract predators of their natural enemies. In addition, the exploitation of the plants and their defences is facilitated by a vast number of behavioural, morphological and physiological adaptations by herbivores Accounting for this diversity has been a major area of research for nearly a century. The seminal article,…show more content…
What happened in the past might be a different picture to what we have envisaged so far. Thompson (1999) has proposed that there are crucial components to coevolution. These need to be recognised before we can fully understand coevolution. Firstly, phylogenetic studies are providing five kinds of data important in interpreting the historical context of coevolving interactions. 1) Shared traits. Phylogenetic studies are allowing us to evaluate which traits of interacting species were already present in the hosts ancestors. This allows us to determine whether traits are coevolved or merely a trait exhibited as a consequence of the organisms genotype. For example, Yucca plants provide a source of food for host specific Yucca moths, with which they are believed to have coevolved. Examining the phylogenetic trees of these moths elucidated this. Most moths in this family (Prodoxidae) exhibited host specificity (Davis et al 1992). Before this technology, people would have assumed the specificity of the Yucca moth to be a product of the coevolution. This brings up a useful comment by Vermeij (1994). Almost all inferences about coevolution are derived from the existence of trends in the expression of traits that function during interactions between species. Evolutionary trends have often been found by analysing ancestor-dependant relationships within monophyletic groups, or clades. Although many trends are best sought this way, others cannot in principle be detected

More about Coevolution With Particular Reference to Herbivory Essay

Open Document