黑料网

Abstract

The founder effect is an occurrence when a new colony of crop with few in number is causes for a genetic drift. A large number of genetic resources are losted their genetic variation in this world because of this event. This universe is reach in having ample amounts of genetic resources and the earth has 370,000 - 500,000 species of higher plants out of which approximately 369000 have been described. Now a day several species of plant genetic resources are not known by science whereas a third of the available genetic resources are at a risk of extinction because of the events of the founder effects. This phenomenon is happening when small group of individuals is isolated from the diversified populations as a result of selection of the most preferred crop for specific purposes, domestication and introduction of the crops from abroad and creating of the distances within the selected and the overall population in order to prevent inbreeding providing the new population becoming genetically distinct over the time. Even if the founder effects basically from domestication consisting a fraction of genetic variability of the parental lines it is so important that and can contribute a significant role in domestication and the genetic improvement of the crop whereas the problem is when a preferred traits are intentionally selected from the larger population while ignoring of others is takes place that resulted in loss of genetic diversity within the massive crop species as a result of wide spread adoption of the elite or selected genotypes substituting the existing land races and wild cultivars and colonizing of their natural habitats. Even if the exotic crop is dominated for a given period of time, however it will be fallen after a period of time under a harsh circumstance due to the constraints like climate changes, biotic and abiotic factors as a result of it doesn’t have a resistant gene that enables it to overcome the aforementioned constraints. Even if crop introduction is inevitable, it is very valuable and it needs to be to protect the indigenous crop plants in order to prevent them from extinction as a result of the effects of the founder effects. Since indigenous crops are gifted in polygenic in nature it serves as a source for resistant genes that enable to withstand the harsh environmental circumstances and also it is very important to play a vital role in providing gene of interests in crop improvement that uses as a means of supporting in maintaining the genetic diversity of the crop population. As crop plant is displaced from its original agroecologies as a result of various means of agents then the crop is enforced to alter their gene pool that causing to the genetic bottle neck simply because of domestication and founder effects and it is that is why in the field of breeding work any selection imposes causes for reduction of genetic diversity because of in selection it favors the best genotypes while ignoring of the rest of the population than conserving to use for the other purposes. Therefore, the objective of this paper is to review on the influence of founder effects on the crop evolution and to understand its causes, mechanisms and the existing remedies to overcome the problems