Principles Of Animal Behaviour Dugatkin Pdf |BEST| Free 19
Click Here ->>> https://shoxet.com/2t9Q6R
An example of homoplasy is the well-known case of the Homosapien Cladogram, a cladogram of the evolutionary history of the higher primates. The original cladogram was reconstructed from a combination of morphology and behaviour and was published by Robert Broom in his 1923 paper “The Earliest Man”.
In sympatric speciation (as well as the closely related non-sympatric varieties),[236][237][238] gene flow between two populations – of either the same or different species – is temporarily prevented by geographic, ecological or behavioural barriers, such as an arms-race between the two species in competition for the same habitat, or the evolution of intense competition and antagonistic behaviour, which may escalate into lethal attacks and ultimately lead to one or both of the species becoming extinct.[236] This mechanism is often referred to as reproductive character displacement. Reproductive character displacement is important in the evolution of many species, including many mammals, especially in the case of body size.[239]
Mesic speciation occurs when ecological selection and isolation lead to the evolution of reproductive isolation between populations.[236][237] Mesic speciation is most often seen in plants and animals with heterostyly. Heterostyly is a form of floral dimorphism that results in two morphs of flowers on the same plant, one with long and flexible stamens and the other with short and narrow stamens. The difference in stamen length and/or shape between morphs provides the basis for adaptation, leading to reproductive isolation. This can be a very rapid form of divergence, as seen in Androsace species with heterostyly, where the speciation event took less than 12 million years.[238]
Another mode of speciation, sympatric speciation, occurs when populations become reproductively isolated without geographical barriers.[240] When two species coexist, they may adapt to the presence of one another by evolving similar shapes, sizes, or behaviours that are not shared by a third species. This gives the appearance of a new species, even though the populations are still capable of interbreeding and producing viable offspring.[241] The two reproductively isolated species may diverge in the same way as allopatric or sympatric speciation: via random genetic drift or an accumulation of mutations. If the barrier is strong enough, the two species may evolve to the point of being reproductively isolated from a third species. The populations are termed incipient species.[242] 827ec27edc