Earliest horses show past global warming affected body size of mammals

June 1st, 2012

By Danielle Torrent

Florida Museum researcher Jonathan Bloch compares the upper jaw of Sifrhippus, the earliest known horse species (foreground), to the upper jaw of a modern-day horse. © Florida Museum photo by Kristen Grace

These days, climate change is a hot topic.

What will happen as temperatures rise more rapidly than humans have documented in modern history? Will birds and mammals flock or will they be able to acclimate? Who will become extinct?

In recent years, scientists have strived to understand the atmosphere’s balance of greenhouse gases to create models that predict rapid climate change, a process humans have accelerated with deforestation and the burning of fossil fuels. Scientists at the Florida Museum of Natural History and anthropology department on the University of Florida campus explored the issue by studying an extreme short-term global warming event known as the Paleocene-Eocene Thermal Maximum that occurred about 56 million years ago.

During this 175,000-year climate event, increased concentrations of carbon dioxide in the atmosphere and oceans caused average global temperatures to rise 10 to 20 degrees.

“The PETM is really important because it marks the beginning for the first appearance of several major groups of mammals, including crown-group primates (ancestors of modern primates) and the first even- and odd-toed modern ungulates (mammals with hooves),” said associate curator of vertebrate paleontology Jonathan Bloch, co-author of a study published in Science Feb. 24, 2012, that correlates temperature with mammalian body size. “This sets the scene for the entire diversity of animals we see on the planet today.”

The study shows how mammals responded to past climate change: As temperatures increased, their body size decreased.

Researchers focused on the evolution of Sifrhippus, the earliest-known horse, which first appeared in the North American fossil record during the Paleocene-Eocene Thermal Maximum. By analyzing the size and isotopes of fossils collected in Wyoming’s Bighorn Basin, researchers traced the evolution of Sifrhippus from an estimated 12-pound animal that shrank during a 130,000-year period about 30 percent to 8.5 pounds, and then increased to about 15 pounds during the next 45,000 years.

“Horses started out small, about the size of a small dog like a miniature schnauzer,” Bloch said. “What’s surprising is that after they first appeared, they then became even smaller and then dramatically increased in size, and that exactly corresponds to the global warming event, followed by cooling. It had been known that mammals were small during that time and that it was warm, but we hadn’t understood that temperature specifically was driving the evolution of body size.”

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Coastal forests retreat as sea levels rise

May 1st, 2012

By Francis E. “Jack” Putz

Turtle Creek; Withlacoochee Gulf Preserve. © Photo by Jennifer Seavey

That sea levels are rising is hardly new news–they have been doing so since the end of the last major glaciation some 18,000 years ago. The current rate of rise, a little more than a tenth of an inch per year, is also not that unusual–6,000–8,000 years ago the seas were often rising 10 times faster. What is different today and the reason for concern is that back then in response to rapidly rising waters, coastal dwelling Floridians just picked up and moved uphill, leaving their villages, burrows, nests and rooted parents behind. Today it is not so easy to move uphill, for humans nor the rest of the biota, but move we must.

The effects of sea level rise are often difficult to differentiate from the myriad of other drivers of coastal change, but the expanses of dead trees looming over Gulf Coast marshes is compelling evidence. The story unfolds very clearly in Yankeetown’s Withlacoochee Gulf Preserve (www.withlacoocheegulfpreserve.com) where saltwater intrusion due to over pumping from the aquifer is not the confounding factor that it is near large cities. The comparatively small tidal fluxes in the Gulf also help in differentiation of the signal of sea level rise from the noise of tides. Another advantage of the Yankeetown marshes and coastal forests is that they are perched atop a stable limestone platform and not on subsiding mucks like in the Mississippi Delta. Finally, as a study site or the destination for an outing, Withlacoochee Gulf Preserve is startlingly beautiful.

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Researchers tag record number of endangered sawfish

April 24th, 2012

By Danielle Torrent

Sawfish saw

After catching small-toothed sawfish, researchers tie the rostrum with a rope to help hold the fish while tagging it. © Photo by Jim Wilcox

Scientists studying marine animals at the Florida Museum of Natural History seem to be living the high life, heading to the coast for fishing trips in the name of research.

But when you take away the refreshments, the relaxation most people associate with going fishing and consider they’re looking for one of the most rare and dangerous animals in Florida’s waters, being on a boat takes on a new meaning.

Tasked with developing a conservation plan for the federally endangered small-toothed sawfish, researchers have been attempting to track their movement patterns since 2010. But until their last trip in late March that resulted in eight tagged individuals, they had only hooked a few of the massive creatures in the Florida Bay.

“I was pretty surprised, I mean we caught one a day, and on two days, we caught two a day,” said marine biologist Yannis Papastamatiou, who is responsible for placing tracking devices on the animals. “And on one of those days, we caught two at exactly the same time.”

The crew is often accompanied by George Burgess, director of the Florida Program for Shark Research at the Florida Museum, but Burgess spent this trip nursing sawfish wounds inflicted during a previous excursion in Florida Bay.

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Museum researchers unlock genetic data of recently rediscovered "hidden" native Florida plant

March 1st, 2012

By Danielle Torrent

Matthew Gitzendanner

Florida Museum researcher Matthew Gitzendanner displays the holotype specimen of Ziziphus celata, endemic to central Florida. © Photo by Jeff Gage

In 1947, a small package containing an unknown plant specimen arrived at the Florida Museum of Natural History Herbarium. For 37 years, the thorny stem and leaves sat pressed between pages of a yellowed newspaper, filed in a cabinet among the vast library of Florida plants, until University of Florida botanist Walter Judd encountered the specimen in 1984. Knowing it was from the Lake Wales Ridge in central Florida, Judd and herbarium curator David Hall traveled to the area in search of wild populations, but returned to Gainesville empty-handed. Pronouncing it extinct, they published a paper naming the mysterious plant Ziziphus celata.

“Celata means hidden, because the plant was hiding from us,” Judd said. “We searched every little scrub patch that we found, but we didn’t see it – we were hoping that this would kind of be like the pebble that gets the avalanche rolling, and soon enough, there was an article written about the plant in the local newspaper.”

The media attention attracted amateur botanists and collectors to the field, and three years later, native populations of Ziziphus celata were re-discovered. But the excitement was short-lived, as researchers soon learned the species was self-incompatible, meaning two different plants are needed to produce seeds.

In 2007, the tide turned again when additional populations were found, and recent research on the plants revealed they have some genetic diversity, giving new hope to the 15-year effort to re-establish one of the state’s most rare and endangered plants.

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Museum archaeologist uses tree-ring data to test climate events in ancient Mesoamerican codex

February 1st, 2012

By Danielle Torrent

In ancient Mesoamerica, as the Aztec calendar predicted the end of the world with a total solar eclipse followed by a cataclysmic earthquake, neighboring cultures also looked to the heavens for signs of their future.

Their painted books depicted solar eclipses, comets and other celestial patterns, for the skies brought good fortune or bad, a successful crop season or dreaded famine.

Predictions and records of climate cycles appear in the Codex Borgia, the finest of the five Borgia group manuscripts to survive the Spanish conquest of the Aztec in 1521. Many scholars over the last few centuries have offered interpretations of events documented in the Codex Borgia, a 76-page screen-fold book made of deerskin, but they had not taken into account its origin in Tlaxcala and notation of real events.

Susan Milbrath

Florida Museum Curator of Latin American Art and Architecture Susan Milbrath displays a copy of the Codex Borgia in front of a replica of the Aztec calendar stone in the Dickinson Hall courtyard on the UF campus. © Florida Museum photo by Kristen Grace

New research using tree-ring data to match climate events described in the codex shows dates that may be deciphered using the Aztec calendar.

“Mesoamerica is a single cultural area and the calendar works similarly — many of the deities are the same, but unless we establish who made this codex definitively, we can’t talk about anything,” said Florida Museum of Natural History Curator of Latin American Art and Architecture Susan Milbrath. “Initially, Aztec sources were used to interpret it, then the Mixtec scholars around the 1960s started to claim it. Now, with the work of Tony Aveni and this study, we can definitively say it was Tlaxcaltec, but it’s taken about 40 years for it to get pulled back into the Aztec dialogue.”

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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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