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Headline: RAW VIDEO: Bat's Amazing! Scientists Unravelling The Evolutionary Secrets Behind Vampires' Bites
Caption: This Halloween, researchers have begun to unravel the secret to how bats evolved their bites - and thus how some evolved to become vampires. There are more than 200 species of noctilionoid bats, the family that includes bloodsucking critters, which live mostly in the American tropics. Yet despite being close relatives, their jaws evolved in wildly divergent shapes and sizes to exploit different food sources - from fruit and insects to more gory fare. Bats’ jaws are actually quite similar to humans, the researchers say - although those with longer jaws have room for more teeth. “Bats have all four types of teeth — incisors, canines, premolars and molars — just like we do,” said co-author Sharlene Santana, a University of Washington professor of biology and curator of mammals at the Burke Museum of Natural History & Culture. “And noctilionoid bats evolved a huge diversity of diets in as little as 25 million years, which is a very short amount of time for these adaptations to occur.” Today different noctilionoid species feast on insects, fruit, nectar, fish, and yes, even blood — since this group also includes the infamous vampire bats. Lead author Alexa Sadier, now of the Institute of Evolutionary Science of Montpellier in France, who began this project at the University California, Los Angeles, said: “There are noctilionoid species that have short faces like bulldogs with powerful jaws that can bite the tough exterior of the fruits that they eat. Other species have long snouts to help them drink nectar from flowers. How did this diversity evolve so quickly? What had to change in their jaws and teeth to make this possible?” To find out the evolutionary mechanisms at work, the team used CT scans and other methods to analyse the shapes and sizes of jaws, premolars and molars in more than 100 noctilionoid species. The bats included both museum specimens and a limited number of wild bats captured for study purposes. They then compared the relative sizes of teeth and other cranial features among species with different types of diets, and used mathematical modeling to determine how those differences are generated during development. Bats with long jaws — like nectar-feeders — or intermediate jaws, like many insect-eaters, tended to have the usual complement of three premolars and three molars on each side of the jaw. But they found that in noctilionoid bats, certain “developmental rules” caused them to generate the right assortment of teeth to fit in their diet-formed grins. Bats with short jaws - like the vampire subfamily and fruit bats - tended to ditch the middle premolar or the back molar, if not both. The shorter jaw may also explain why many short-faced bats also tended to have wider front molars - and thus how the vampire bats developed their distinctive look. “When you have more space, you can have more teeth,” said Sadier. “But for bats with a shorter space, even though they have a more powerful bite, you simply run out of room for all these teeth.” She added: “The first teeth to appear tend to grow bigger since there is not enough space for the next ones to emerge.” However, the duo say more research is needed until we fully know the secrets of the spooky mammals. “This project is giving us the opportunity to actually test some of the assumptions that have been made about how tooth growth, shape and size are regulated in mammals,” said Santana. “We know surprisingly little about how these very important structures develop!” Many studies about mammalian tooth development were done in mice, which have only molars and heavily modified incisors. Scientists are not entirely sure if the genes and developmental patterns that control tooth development in mice also operate in mammals with more “ancestral” sets of chompers — like bats and humans. Sadier, Santana and their colleagues believe their project can answer these questions in bats — along with many other outstanding questions about how evolution shapes mammalian features. They’re expanding this study to include noctilionoid incisors and canines, and hope to uncover more of the genetic and developmental mechanisms that control tooth development in this diverse group of bats. “We see such strong selective pressures in these bats: Shapes have to closely match their function,” said Santana. “I think there are many more evolutionary secrets hidden in these species.”
Keywords: bats,vampires,fruit bats,animals,halloween,feature,photo,video,nature,natural world,science,evolution
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