Washington, Dec 21 (ANI): New research has determined that the female beaked whales' apparent attraction to the tusks in the male of the species, may have spurred the development of new species.
The unusual tusks-found on the outside of the male's mouth-have baffled scientists because they are not used for capturing prey, according to study co-author Scott Baker, associate director of the Marine Mammal Institute at Oregon State University.
"Up until now, the purpose of the beaked whale tusks has been mysterious," he said.
Existing beaked whale populations are found in nearly every ocean. Lead author Merel Dalebout of the University of New South Wales, Australia, and Baker, have discovered new species as recently as 2002.
These rare whales are mysterious, because they spend much of their time at great depths searching for food-primarily squid, which the whales suck up like a vacuum cleaners.
"There are several beaked whale species that are still known from only a handful of specimens (strandings) and some have never been seen alive," Dalebout said.
Robert Pitman, a marine biologist with NOAA, recently studied what may be a new beaked-whale species near Palmyra Island in the Pacific Ocean.
"For people interested in cetacean evolution the most perplexing problem has always been: Why are there so many species of beaked whale?" he said.
For example, there are only three known right whale species.
Baker and Dalebout, using whale DNA samples, set out to answer that question by piecing together how divergent, and often geographically isolated, species are related.
"When populations become isolated, we expect them to adapt to different niches and diverge-geographic isolation creates speciation," said Baker.
But in the ocean, these geographic barriers are absent, and other forces, like sexual selection, could be involved in the formation of new species.
In the case of the beaked whale, Baker's team noticed that tusks often differed between closely related species, particularly when they were known to overlap in their distribution.
The researchers hypothesize that the large whale teeth evolved over time to help females distinguish males of one species from males of another.
"Male beaked whales of different species are rather similar in size and appearance," Baker said. "In a way these teeth are a kind of ornament or signal for the females," he added.
According to NOAA's Pitman, "Sexual selection can be an important spur for evolutionary innovation." (ANI)