In the 1980s, several researchers proposed the flying primate hypothesis, a radi

Question

In the 1980s, several researchers proposed the flying primate hypothesis, a radical reorganization of the phylogeny of bats. The key features of this hypothesis were that a) the order Chiroptera was polyphyletic, b) that the megachiroptera, the large fruit eating bats like the flying foxes, and the microchiroptera, the small insect-eating bats like our local little brown bats, had each independently evolved flight, and c) that the megachiroptera were more closely related to primates. Bats were clustered with tree shrews and colugos in the superorder Archonta. The proposal did not last long, falling apart as new data was collected. In a 2-3 page essay (typed, double- spaced, 12 point font), summarize the initial evidence for the flying primate hypothesis and the early arguments for and against it, and then the later evidence that later effectively ruled it out. That the hypothesis is not valid is not in dispute, so this is not an essay about whether it is correct or not — focus on describing the phylogenetic methodology used to advance and test the idea.

Explanation / Answer

In evolutionary biology, the Flying Primate Hypothesis posits that megabats, a subgroup of Chiroptera foem an evolutionary sister group of primates. The hypothesis began with Carl Linnaeus in 1758, and was advanced by J.D. Smith in 1980. it was proposed in its modern form by australian neuroscientist in 1986 and he discovered that the connections between the retina and superior colliculus( a region of midbrain) in the megabat Pteropu were organized in the same way found in primates, and different from all other mammals. This was followed by a longer study published in 1989 , in which this was supported by many other brain and body characterstics. Pettigrew suggested that flying foxes, colugos, and primates were all descendents of the same group of early arboreal mammals.   The megabat flight and the colugo gliding could be both seen as locomotory adaptations to a life high above the ground.                           The flying primate hypothesis met resistance from many zoologists. Its biggest challenges were not centered on the argument that megabats and primates are evolutionarily related , which reflects earlier ideas( such as grouping of primates, tree shrews, colugos, and bats under the same taxonomic group, the superorder Archonta). rather, many biologists reisted the implications that megabats and microbats formed distinct branches of mammalian evolution, with flight having evolved twice. This implications was borne out of the fact that microbats do not resemble primates in any of the neural characterstics studied by Pettigrew, instead resembling primitive mammals such as Insectivora in these respects.More recently , the flying primate hypothesis was rejected when scientists compared DNA of bats to that of primates. These genetic studies support the monophyly of bats.

Phylogenetic methods can produce biased estimates of phylogeny when base composition varies along different lineages. Pettigrew has suggested that base composition bias is responsible for the apparent support for the monophyly of bats from several different nuclear and mitochondrial genes.

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