In other areas, like along the eastern coast of Australia, only the reef manta ray are seen. For example, only the giant manta ray has been sighted in the eastern Pacific Ocean, in locations such as Mexico, Costa Rica and Ecuador. Since their separation, we have learned that both species have wide distributions around the globe and share the world’s oceans in mosaic sympatry. It is not often that the world recognises the existence of such a large previously-unrecognised giant! How were these species different and what drove them to speciate in the first place? Having previously been considered a monotypic genus, with a single recognised species, our ground-breaking study in 2009 split the genus manta into two visually distinguishable species, Manta alfredi, the reef manta, and Manta birostris, the giant manta. Today, these same problems continue to thwart efforts to clarify taxonomic issues within this genus, leaving many of us frustrated yet challenged.įemale scuba diver swimming with a young male manta ray, Kona District, Hawaii © Wikimedia Commons However, the rarity of adequate specimens in collections or the accessibility of those from fisheries stymied early taxonomic efforts to accurately describe manta rays. These numbers are not surprising given the unique appearance of manta rays and their impressive size, both of which prompted many early ocean explorers to lodge reports of their encounters with this giant ray. The classification of the genus manta has been notably convoluted, with the group having as many as 25 different species names over time. One piece of the puzzle at a time, and using an ever-expanding array of techniques to help us along, we are unravelling the mystery behind the evolution of the world’s largest ray. Over the last decade, our team of scientists have been investigating such questions about manta rays. These days, however, answering these questions invariably forces us into the lab, where we can delve deeper into the complex world of DNA. As scientists, we can learn many things from studying the appearance, distribution and behaviour of a species in the field. We closely scrutinise detail after detail looking for clues that might answer these questions and more. These are the types of questions that fill the mind of an evolutionary biologist – a never-ending suite of uncertainties and intrigues. If there were another species of human on the planet, what would they be like? Would they look like us? How would they differ? Would we continue to evolve separately as different species? Or would some members of our species (or theirs) cross the species boundary one day and start hybridising? Perhaps the most intriguing question of all is, when and why did the split between our species and theirs (speciation) take place? Intermediately, we might have some habitats just for us, and others, just for them, peppered with a few shared habitats where we “mix” (mosaic sympatry). Alternatively, we may co-exist in close proximity, side by side in every country, city, town and village (pure sympatry). The two of us might occupy entirely different hemispheres or continents (allopatry). Andrea Marshall and Tom Kashiwagi take us through the history of manta rays:Ĭan you imagine sharing this planet with another species of human? Let’s say with the Neanderthal man.
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