8) You are studying a group of chameleons that are currently present across many southern hemisphere landmasses. Species 1 is found in Australia, species 2 in Madagascar, species 3 in South America, species 4 in New Zealand, species 5 in Africa, and species 6 in New Guinea. You hypothesize that the current species distribution is due to an ancestral chameleon that inhabited Gondwana and was speciated as the continent broke up. Draw a phylogeny that is consistent with this hypothesis. (Assume that this is the order of breakup: Madagascar - 160 mya, Africa - 100 mya, New Zealand - 85 mya, Australia and New Guinea 60 mya, and finally South America and Antarctica split 35mya). It turns out that most of the distribution is due to vicariance, but species 2 (Madagascar) dispersed from Africa, and species 4 (New Zealand) dispersed from Australia after the Australia and New Guinea lineages split. Draw a phylogeny consistent with this hypothesis.

Question

Biology

Ralph David

18 July, 10:05

8) You are studying a group of chameleons that are currently present across many southern hemisphere landmasses. Species 1 is found in Australia, species 2 in Madagascar, species 3 in South America, species 4 in New Zealand, species 5 in Africa, and species 6 in New Guinea. You hypothesize that the current species distribution is due to an ancestral chameleon that inhabited Gondwana and was speciated as the continent broke up. Draw a phylogeny that is consistent with this hypothesis. (Assume that this is the order of breakup: Madagascar - 160 mya, Africa - 100 mya, New Zealand - 85 mya, Australia and New Guinea 60 mya, and finally South America and Antarctica split 35mya). It turns out that most of the distribution is due to vicariance, but species 2 (Madagascar) dispersed from Africa, and species 4 (New Zealand) dispersed from Australia after the Australia and New Guinea lineages split. Draw a phylogeny consistent with this hypothesis.

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Judith Oconnell · Answer 1

Dispersion and vicariance are the processes by which speciation is generated in biogeography.

A phylogeny represents the evolutionary relationships between different species.

In this phylogeny, species 5, 1, 6 and 3 originated from vicariance processes, and their position in the phylogenetic tree is due to the order of separation of the mentioned regions. Species 2 and 4 originated from dispersal processes, and are expected to have a closer evolutionary relationship with the species that were in the areas from which they were dispersed, in this case, with Africa and Australia respectively.