Museum ornithologist researches 6,000 years of history in the Bahamas

February 1st, 2012

By Danielle Torrent

The field of restoration ecology, in which native flora and fauna are re-established to create more sustainable environments, is taking off in the 21st century as researchers become more aware of the potentially negative impacts of invasive, non-native species. Humans are among the “non-natives” in many areas, having taken over as apex predators in many situations. In the Bahamas, the arrival of humans about 1,000 years ago led to a considerable disruption of the natural food chain.

beach

The beach on the west side of Clifton National Heritage Park on New Providence Island. Photo by Michael Dion

With a three-year $164,000 National Science Foundation grant awarded in September 2011, Florida Museum of Natural History ornithologist David Steadman is digging into 6,000 years of history, with hopes that a better understanding of how island organisms respond to human influence may aide efforts to restore a more functional ecosystem. By collecting fossils from the Bahamas over the last 6,000 years, well before humans reached the area, he will also analyze how plant and animal communities responded to long-term natural environmental fluctuations.

“People arrived in the Bahamas and soon they wiped out the tortoises, they wiped out the crocodiles, and became a new apex predator capable of eating just about anything, marine or terrestrial,” said Steadman, Florida Museum natural history department chair. “People are also warm-blooded, or homeotherms, so we need more energy per pound of body weight to keep going. This requirement rearranges energy flows. All that gets complicated even further by people wiping out certain species, whether they’re prey species or other predators, and introducing non-native plants and animals.”

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Genetic analysis of hybrid plants may have far-reaching evolutionary consequences

January 1st, 2012

By Danielle Torrent

Doug Soltis

Study co-author Doug Soltis observes one of the artificial Tragopogon miscellus hybrids researchers remade in UF greenhouses. © Florida Museum photo by Jeff Gage

For morning drivers on the roadways of the northwestern U.S., an innocuous purple or yellow flower similar to a daisy should be a familiar sight. Widespread and often considered a weed, goatsbeard is also known as “John-go-to-bed-at-noon” because its flower only blooms for a few hours in the morning.

The European parent species of this plant never produced fertile hybrid offspring. But once the parents arrived in North America about 80 years ago, they not only formed hybrids, but those hybrids then experienced genome (chromosome) doubling. The parents yielded two new species (Tragopogon mirus and Tragopogon miscellus) native only to North America. Plants of these new species have since multiplied throughout the Pacific Northwest, with estimates of more than 10,000 near Spokane, Wash.

To better understand this phenomenon of genome doubling, which is common in plants, including many crops, Florida Museum of Natural History researchers re-created T. miscellus in UF greenhouses and analyzed its genes and chromosomes to find patterns that may have far-reaching evolutionary consequences.

“We caught evolution in the act,” said Doug Soltis, a distinguished professor in UF’s biology department. “New and diverse patterns of gene expression are seen and these may allow the new species to rapidly adapt in new environments.”

Pam and Doug Soltis have been studying T. miscellus for more than 20 years, and a series of publications have given scientists a clearer view into what happens when a hybrid species experiences a genome duplication event, or polyploidy, following hybridization.

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Museum researchers document evidence of mimicry in caterpillars

December 1st, 2011

By Danielle Torrent

caterpillar mimicry

This image shows four different Neotropical caterpillar species from eastern Ecuador that have adapted the same warning color, a mimicry technique, to deter predators. Pictured are Pseudoscada florula, from top, Oleria sexmaculata, Ithomia amarilla and Forbestra olivencia. © Photos by Keith Willmott | Illustration by Kristen Grace

Exactly 150 years ago, Henry Walter Bates described mimicry based on his observations of adult butterflies in the Amazon, thus contributing key evidence supporting Darwin’s then novel theory of natural selection.

Recently, while doing fieldwork in the lowlands of eastern Ecuador, Florida Museum of Natural History assistant curator of Lepidoptera Keith Willmott noticed another prime example of mimicry. Instead of looking up at the flyers, he found bright coloration in an earlier growth stage of butterflies — similar bright coloration in caterpillars was repeated in several unrelated species of ithomiine butterflies and again in a sawfly larva. Clad in blue and yellow with black tips, different species of the crawlers were not disguised as bird droppings or natural objects like many other caterpillars, and they were saying something different to their enemies: “Look out, we’re poisonous!”

Meanwhile, on the Caribbean island of Hispaniola, fellow Florida Museum lepidopterist Andrei Sourakov was documenting another curious example of different caterpillar species with similar, conspicuous color patterns. A banded black, white and yellow pattern appeared in several species of danaine caterpillars, which include the monarch butterfly and its relatives.

Together, the researchers, who work in the Florida Museum’s McGuire Center for Lepidoptera and Biodiversity, documented some of the most extensive examples of mimicry in caterpillars, in which different species mimic others as a defense against predators.

“Previous papers discussing mimicry mostly discuss a single, isolated case, typically involving a pair of species, but this is not just one pair, there are several species involved,” said Andre Victor Lucci Freitas, a professor in the Instituto de Biologia at Universidade Estadual de Campinas, who is familiar with the study. “There are lots of papers discussing mimicry in adult insects, but there are very few exploring mimicry of immature stages, like the caterpillar.”

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Florida's invasive amphibian and reptile problem leads world

November 2nd, 2011

By Danielle Torrent

Burmese Python

The Burmese python is Florida’s largest invasive species documented in a recent study led by Florida Museum researcher Kenneth Krysko. © Photo by Eric Zamora

 

During the 1800s, the world was going through transformations steered by war, invention, scientific innovation and the discovery of new land. The time period saw the collapse of some empires and the rise of others, from the British and Japanese to the booming United States of America. The Industrial Revolution brought about the invention of railroads, and cargo ships made an unprecedented number of journeys to the New World. But unbeknownst to conquerors, amphibians and reptiles were along for the ride, and their presence is having a seemingly irreversible impact today.

In Florida, it started with the first documented introduction of the Greenhouse Frog in 1863, a native of the West Indies. This species has become widespread and occurs in areas where many native frogs are now seldom seen. Circa 1887, cargo ships brought the brown anole from Cuba to the state, and the small, brown lizard is now one of Florida’s most easily recognized wildlife species. The state’s largest established invader, the Burmese Python, made its way from the rainforests of Southeast Asia to become household pets for Floridians, and recent studies show the devastating effects these up to 20-foot-long creatures have on native wildlife in the Everglades. In total, Florida has seen at least 137 introductions of non-native amphibians and reptiles, more than anywhere else in the world.

“Most people in Florida don’t realize when they see an animal if it’s native or non-native and unfortunately, quite a few of them don’t belong here and can cause harm,” said Kenneth Krysko, Florida Museum of Natural History herpetology collection manager and lead author of a 20-year study published in Zootaxa Sept. 15, 2011, documenting all known introductions to the state from 1863 to 2010. “No other area in the world has a problem like we do, and today’s laws simply cannot be enforced to stop current trends.”

Until about 1940, the introductions were incidental, primarily resulting from the cargo trade. But in the 1970s and ’80s, pet dealers began importing more species to meet the boom in popularity of exotic terrarium animals. The study attributes 84 percent of the introductions to the pet trade, with 25 percent traced to one animal importer.

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Museum researcher uses DNA bar coding to improve tropical butterfly classification

November 1st, 2011

By Danielle Torrent

Calisto confusa

Calisto confusa is named for its tendency to be confused with other butterfly species. Florida Museum lepidopterist Andrei Sourakov used DNA bar coding in a recent study to distinguish C. debarriera as a separate species, rather than a subspecies of C. confusa. © Photo by Andrei Sourakov

When Charles Darwin journeyed to the Galapagos Islands in the 1830s, he collected some mysterious birds that later helped shape his theory of evolution by natural selection. Dubbed “Darwin’s finches,” they became famous as an example of adaptive radiation, in which animals evolve from a common ancestor to utilize different ecological niches.

Two centuries later, on the Caribbean island of Hispaniola, a Florida Museum of Natural History researcher was attracted to a group of insects he calls “Darwin’s butterflies,” because of their similarly high degree of diversity derived from a common ancestor. But it wasn’t until 20 years after beginning his research on the genus Calisto as a University of Florida Ph.D. student that Andrei Sourakov found the missing link for understanding how the group should be classified.

“DNA bar coding was the perfect tool to look at this genus because a lot of these species were separated based on only wing patterns, and it’s difficult to prove whether these differences correspond to species, or just represent variation,” said Sourakov, Florida Museum Lepidoptera collection coordinator. “DNA actually allows us to evaluate if and when the gene exchange occurred.”

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Museum researchers name new ancient crocodile relative from land of Titanoboa

October 1st, 2011

By Danielle Torrent

Did an ancient crocodile relative give the world’s largest snake a run for its money? In the post-dinosaur world of giants, Florida Museum of Natural History researchers discovered a new species related to crocodiles they say ate the same freshwater fish as Titanoboa.

croc and Titanoboa

This illustration shows how Acherontisuchus guajiraensis looked in its natural setting. Titanoboa, the world’s largest snake, is pictured in the background. © Florida Museum illustration by Danielle Byerley

Sixty-five million years ago, when a mass extinction wiped out dinosaurs, flying reptiles, large swimming reptiles and many other marine animals, few survivors were left to tell the story.

But University of Florida researchers recently unearthed the second member of a family that lived alongside the beasts, yet mysteriously survived the theorized asteroid strike that forever changed the atmosphere of the world.

“The same thing that snuffed out the dinosaurs killed off most of the crocodiles that were alive at the time,” said Florida Museum of Natural History graduate student Alex Hastings, lead author of a study describing the new species of dyrosaurid published Sept. 15, 2011, in Palaeontology. “The dyrosaurids are one of the few groups to survive the extinction and later become more successful.”

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Florida Museum researcher sheds light on ancient climate change

September 1st, 2011

By Danielle Torrent

Karen Walker

Florida Museum archaeologist Karen Walker displays a southern quahog clam shell and other specimens from Pine Island. Using isotopic information extracted from the items, researchers determined cooler, drier temperatures and lower sea levels affected the island’s inhabitants from A.D. 500 to 800. © Photo by Kristen Grace

The mysterious appearance of numerous ancient duck bones dating to the sixth century at the Pineland archaeological site on Pine Island in southwest Florida was the first clue to one Museum researcher’s new understanding of the state’s environmental history.

Karen Walker, assistant scientist of south Florida archaeology at the Florida Museum of Natural History, knew it was odd to find so many bones since the winter migratory range for ducks normally extends to the northern Gulf Coast, but not as far as south Florida. This suggested a climate cooler than today’s.

Other clues from the same period include a change in residents’ firewood from black mangrove to pine, suggesting a drier landscape, and a reduction in the number of fish bones, indicating people were eating less fish.

Using isotopic information from southern quahog clam shells and marine catfish otoliths (ear bones) collected at the site, Walker and co-authors Ting Wang and Donna Surge of the University of North Carolina at Chapel Hill confirmed cooler and drier weather characterized southwest Florida from about A.D. 500 to 850. This time span correlates with a wide-scale climate episode known as the Vandal Minimum, which is also associated with lower sea levels.

“When we started out, we thought, ‘Well, why wouldn’t you want it to be cooler in south Florida, it must have been nice,’ ” said Walker, who co-authored the study published online April 11, 2011, in The Holocene. “But in the end, I realized it’s all about fish – if you lose your water, you lose your fish.”

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