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Hybridization without change in chromosome number is called homoploid hybrid speciation. [1] This is the situation found in most animal hybrids. For a hybrid to be viable, the chromosomes of the two organisms will have to be very similar, i.e., the parent species must be closely related, or else the difference in chromosome arrangement will ...
[1] [2] Evidence for speciation by reinforcement has been gathered since the 1990s, and along with data from comparative studies and laboratory experiments, has overcome many of the objections to the theory. [3]: 354 [4] [5] Differences in behavior or biology that inhibit formation of hybrid zygotes are termed
The structure and migration patterns of a population can affect the process of speciation by reinforcement. It has been shown to occur under an island model, harboring conditions with infrequent migrations occurring in one direction, [22] and in symmetric migration models where species migrate evenly back and forth between populations. [26] [30]
Hybridization is an important means of speciation in plants, since polyploidy (having more than two copies of each chromosome) is tolerated in plants more readily than in animals. [ 80 ] [ 81 ] Polyploidy is important in hybrids as it allows reproduction, with the two different sets of chromosomes each being able to pair with an identical ...
The two theories; non-adaptive, and adaptive, are used to explain the evolution of senescence, which is the decline in reproduction with age. [8] The non-adaptive theory assumes that the evolutionary deterioration of human age occurs as a result of accumulation of deleterious mutations in the germline. [8]
Generally, hybridization is more frequently observed in species with external fertilization including plants but also fishes, than in internally fertilized clades. [4] In plants, high rates of selfing in some species may prevent hybridization, and breeding system may also affect the frequency of heterospecific pollen transfer.
Life history theory has provided new perspectives in understanding many aspects of human reproductive behavior, such as the relationship between poverty and fertility. [43] A number of statistical predictions have been confirmed by social data [ citation needed ] and there is a large body of scientific literature from studies in experimental ...
In biogerontology, the disposable soma theory of aging states that organisms age due to an evolutionary trade-off between growth, reproduction, and DNA repair maintenance. [1] Formulated by British biologist Thomas Kirkwood , the disposable soma theory explains that an organism only has a limited amount of resources that it can allocate to its ...