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The modern human Oase 2 skull (cast depicted), found in Peştera cu Oase, displays archaic traits due to possible hybridization with Neanderthals. [57] The early modern human Oase 1 mandible from Peștera cu Oase (Romania) of 34,000–36,000 14 C years BP presents a mosaic of modern, archaic, and possible Neanderthal features. [58]
Genes that are incompatible according to the Dobzhansky–Muller model require three criteria. 1. The gene reduces the fitness of the hybrid, 2. The gene has functionally diverged in each of the hybridising species and, 3. The hybrid incompatibility is only present in combination with a partner gene. [6]
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]
Although many models, both animal and human, have appeared to support this theory, parts of it are still controversial. Specifically, while the evolutionary trade-off between growth and aging has been well established, the relationship between reproduction and aging is still without scientific consensus , and the cellular mechanisms largely ...
[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
Heterosis or hybrid vigor, on the other hand, is the tendency of outbred strains to exceed both inbred parents in fitness. Selective breeding of plants and animals, including hybridization, began long before there was an understanding of underlying scientific principles.
The somatic mutation theory of ageing states that accumulation of mutations in somatic cells is the primary cause of aging. A comparison of somatic mutation rate across several mammal species found that the total number of accumulated mutations at the end of lifespan was roughly equal across a broad range of lifespans. [ 16 ]
The disposable soma theory of aging tells us that a longer lifespan will come at the cost of reproduction and thus longevity is not always correlated with high fecundity. [ 2 ] [ 3 ] Parental investment is a key factor in reproductive success since taking better care to offspring is what often will give them a fitness advantage later in life. [ 4 ]