Search results
Results From The WOW.Com Content Network
The types of barriers that can cause this isolation include: different habitats, physical barriers, and a difference in the time of sexual maturity or flowering. [6] [7] An example of the ecological or habitat differences that impede the meeting of potential pairs occurs in two fish species of the family Gasterosteidae (sticklebacks).
[3]: 354 [4] [5] Differences in behavior or biology that inhibit formation of hybrid zygotes are termed prezygotic isolation. Reinforcement can be shown to be occurring (or to have occurred in the past) by measuring the strength of prezygotic isolation in a sympatric population in comparison to an allopatric population of the same species.
Ecological speciation can occur pre-zygotically (barriers to reproduction that occur before the formation of a zygote) or post-zygotically (barriers to reproduction that occur after the formation of a zygote). Examples of pre-zygotic isolation include habitat isolation, isolation via pollinator-pollination systems, and
For example: If population has the prezygotic isolating allele and the high fitness, post-zygotic alleles and ; and population has the prezygotic allele a and the high fitness, post-zygotic alleles and , both and genotypes will experience recombination in the face of gene flow. Somehow, the populations must be maintained.
A major aspect of speciation research is to determine the nature of the barriers that inhibit reproduction. Botanists often consider the zoological classifications of prezygotic and postzygotic barriers as inadequate. [259] The examples provided below give insight into the process of speciation.
Prezygotic incompatibilities - reproductive barrier acting before fertilization. For example, pollinator isolation, mechanical barriers preventing mating, and sperm/ovule incompatibilities that prevent fertilization. Reproductive isolation - the presence of barriers to successful crossbreeding. Barriers can be classified in a number of ways ...
The barrier of hybrid inviability occurs after mating species overcome pre-zygotic barriers (behavioral, mechanical, etc.) to produce a zygote. The barrier emerges from the cumulative effect of parental genes; these conflicting genes interfere with the embryo's development and prevents its maturation. Most often, the hybrid embryo dies before ...
The lack of geographic isolation as a definitive barrier between sympatric species has yielded controversy among ecologists, biologists, botanists, and zoologists regarding the validity of the term. As such, researchers have long debated the conditions under which sympatry truly applies, especially with respect to parasitism.