Question

Different genes will have different phylogenetic histories among two species. Explain this in terms of mutations and in terms of coalescence processes?

Do different genes have different coalescence times? What is an adaptive radiation? Why is it significant that most adaptive radiation examples we use come from islands? -Why do we need different species concepts for fossils, for bacteria and other microbes, and for sexually mating organisms like most living plants and animals?

Answer 1

Different genes will have different phylogenetic histories among two species. This is because of differnet selection pressure on two species due to different environmental conditions. So, a particular species can exhibit varied degree of mutation and differential rate of selection of mutations by natural selection based on the reproductive and survival fitness. Similarly, different genes may or may not exibit the same topology as compared to the ancestral species owing to incomplete lineage sorting. This occurs when ancestral population size is very large as compared to their evolutionary history and the halotypes of two different species merge into each other so closely that halotype of one of the species exhibit markable similarties with some other remote species.
Diversification of ancestral form into different forms to occupy diverse ecological niche is referred to as adaptive radiation. Presence of untouched environmental zones in remote islands which are never occupied by ancestral species cause most of the adaptive radiations to occur in these islands.