Dwarf Manatee Possible New Species
Rainforest Manatee Raises Questions of Species vs Subpopulation
Feb 6, 2008
The recently discovered dwarf manatee (Trichechus bernhardi sp. nov) is being proposed for recognition as a separate species from the Amazonian manatee (T. inunguis). Marc van Roosmalen, who found the petite manatees in Brazil’s Amazon, believes they should be considered a separate species and given protection as Endangered. Other scientists sugggest that they are a subpopulation of the Amazonian manatee, which is listed as Vulnerable.
Evidence for a New Species
The dwarf manatee lives in shallow, fast running water and feeds on different species of aquatic plants from those than the Amazonian manatee, which prefers deeper slower moving waters and the plants found there. During the dry season the dwarf manatee may not be able to move out of the Rio Arauazinho and intermingle with the Amazonian manatee in the Rio Aripuana. This means that interbreeding between the two populations is not very likely.
Dr Roosmalen has provided evidence for dividing the Amazonian manatee into two species, including documentation of variation in size, shape, feeding behavior and environment between the two animals. Differences in skulls and jawbones are also present. The Amazonian manatee is separate species from the West Indian Manatee (Trichechus manatus) which prefers a saltwater habitat.
However, even Dr Roosmalen admits that the dwarf manatee shares a significant amount of DNA with the Amazonian manatee. So is it a separate species, a subspecies, or a subpopulation? Even the DNA does not give us clear answers. The Amazonian manatee is noted for having more genetic variability than the West Indian Manatee. So it is possible that the dwarf manatee is a subpopulation that has been physically separated from the main population of Amazonian manatee and has adapted to a different environment.
The Controversy
Scientists who question Dr Roosmalen’s new species point to the fact that he often bases his opinion on one or only a few specimens. There is some concern that his judgment as a scientist is being clouded by his passion for saving the Amazon rainforest. Finding of new endangered species is often useful in protecting places from development or exploitation.
There is no question that Dr Roosmalen has contributed a great deal to the knowledge of Brazil’s Amazon rainforest. Much of his earlier work is highly respected and he has used funds raised from his efforts to buy land deep in the rainforest to protect it. So this is not a man ‘discovering species’ to become rich or famous. But it may be a person who has lost the unbiased viewpoint needed to do good scientific research.
Whatever the decision is regarding the dwarf manatee, it is not difficult to see that protecting the habitat of a unique animal, be it a species, subspecies or subpopulation of freshwater manatee, is worthwhile. Its habitat is an area where there is potential for finding more unrecorded species and that alone should be reason enough to save that habitat.
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