Describe the steps that you would use to infer the phylogenetic relationship of 10 species, including how shared derived characteristics will be helpful.

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bandmanjoe eNotes educator| Certified Educator

What you are trying to do with these ten species is show how it is possible to relate them back to a common ancestor by showing how they all share a common characteristic, or set of characteristics.  This would give some sort of evidence that could be used to argue the evolutionary relationship these species may have developed as they evolved.

For example, in primate evolution, you have all sorts of primates lumped together, such as humans, chimpanzees, gorillas, orangutans, baboons, and macaques.  In setting up a phylogenetic tree, we would first possibly use the existence of a tail as a qualifier.  The presence of a tail would indicate a species that would primarily be an arboreal, or tree-dwelling, species, as opposed to no tail, which would indicate more of a ground-dwelling species. 

Next, the enlargement of the cranial capacity in relation to the rest of the body would make an excellent qualifier.  Such a developed condition would allow for more abstract thinking and problem solving, as exists with humans, chimpanzees, and gorillas.

The primary means of locomotion would be another qualifier to separate the species; humans get around by upright posture on two feet, while gorillas and chimps use a combination of two-legged and all four limbs to move around.

You would look for the existence of physical characterisitcs such as these to make a case for both the separation and organization of the species, while at the same time trying to relate them back to a common ancestor from which they all possibly descended.