Biodiversity

Thursday, May 11, 2006

DISCUSION OF THE ADAPTIVE RADIATION IN THE ORDER INSECTIVORE

Adaptive radiation is the process which is thought to take place when one species change or evolve into two or more other species. On the other side insectivore are thought to be animals which feed on insects. The name insectivore is an indication of their adaptation on feeding on the insects. Insectivore are also thought to be have evolved from the placental mammals (Wikipedia contributors, 2006).

''Adaptive radiation takes place as a result of different population of the species when they become separated from each in terms of reproduction'' (Harbel, 1995: 2). This often occurs when the separated species are able to adapt into the new environments. The way the species diverse and their rapid spread influence the evolvement of organisms to the new ecological environment. Scientists also disagree with each other when coming to whether the morphology of the insectivore is closely related to the placental mammals. It is also said that in the late Eocene and early Oligocene, insectivore underwent an adaptive radiation. By undergoing the adaptive radiation, insectivore manage to produce different lines which seem to have the beginnings of the family of the placental mammals (Myers, 1999).

Insectivore which also look like the placental mammals have also been known by the scientists in the late Cretaceous period. The group Cimolestes, were thought to flourish in the late Cretaceous of the North America. This is evidence which seem to confirm those ''insectivore are the descendent of the placental mammals'' (Harbel, 1995: 1). It is also said that the molecular studies which are done in Madagascar also indicated that the golden moles and the tenrecs are not closely related to the insectivores which are found in the continent of Africa, especially in the Northern part of the continent.

It is further said that insectivore are classified in one order of the placental mammals. This family is thought to include other animals such as ''moles, shrews and hedgehogs'' (Wikipedia contributors, 2006). The name insectivore implies that the animals feed on other small organisms such as worms which are vertebrates animals even though they also feed on organic organisms. Some scientists also believe that the order insectivore generally evolve from the primitive placental mammals. Their argument is based in the study of the fossil remains which found in different continents.

Some scientists said that traditionally, insectivore serve as the basis of the adaptive radiation of the placental animals. Scientists further continue by saying that the insectivore which are living today indicate the closely relationship which comfirmed that they branched off from the evolutionary tree of the placental mammals. But most of the scientists who conducted their research earlier said those insectivore were occupying the central position in the group placelantia.

In conclusion, one can say that the adaptive radiation of the insectivore is still unclear. This is because that scientists themselves, they do not agree with each other whether placental mammals do evolve into the insectivore. Furthermore, scientists do not specify which species evolve after the insectivore. This is because there are still some scientists that believe that insectivore descended from the placental mammals.

References:

Harbel, W. 1995. Eurasian and Tree Shrews. [Online]. Available from:
http://members.vienna.at/shrew/itsesAP95-introduction.html [June 1995, 16:12]

Myers, P. 1999. Order Insectivore. [Online]. Available from:
http://animaldiversity.ummz.umich.edu/site/accounts/information/Insectivora.html [25 May 2005]

Wikipedia contributors. Insectivora [Internet]. Wikipedia, The Free Encyclopedia; 2006 April 11, 11:31 UTC [cited 2006 May 11, 14: 21]. Available from: http://en.wikipedia.org/wiki/Insectivora


Peter Muvhali
CSIR PTA
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1 Comments:

  • You still have probelms with the whole direct quotation thing. And again, your understanding of the theory behind things is hard to gauge. (Btw, not all insectivores belnog to the Order Insectivora). You attempt to tackle issues (such as the nature of adaptive radiation and the extent to which it takes place) that are a bit too difficult for you at the moment.

    Nick

    By Blogger NcK, at May 29, 2006 1:05 PM  

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