You are studying two populations of turtles with different colour patterns that live on opposite sides of a mountain range and occupy the same ecological niche. When individuals from each population are brought together in the lab, they produce offspring whose appearance is intermediate between the two parents. The offspring can breed and reproduce successfully with each other or turtles of either parent population. You sequence three genes, Pigmentosa, Sparkly, and Zippy. For each of the three genes, the two populations differ from each other at a few nucleotides (<1%).
Why is it hard to determine if these two turtle populations belong to the same species or are two different species? In your answer/argument, refer to at least two pieces of evidence from the above scenario. Note, we are NOT asking you to determine if these are the same species or not.
Tips and clarifications: To earn full points for the ‘addresses the question & is scientifically accurate’ part of the holistic rubric, please use the following:
· Possible arguments (if they have one of these that’s enough):
o species concepts rely on different definition of species, so no one concept is universally useful
o species concepts can sometimes give conflicting information about whether two populations are one or two species
· Evidence: need to use two of the following pieces of evidence to support the argument so should be using contradictory outcomes of at least 2 species concepts.
o biological species concept suggests same species because they can interbreed to produce viable fertile offspring
o morphological (aka morphospecies concept) species concept suggests different species (or subspecies) because they have different colour patterns
o ecological species concept suggests the same species because they occupy the same niche
o phylogenetic species concept suggests different species because each gene differs for both populations (although some may suggest the same species because the genes are not significantly different with <1% variation)
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