Monday, April 1, 2019

tangled mass of articulated fish from the Tanis inundation surge depositA study to be published Monday in the Proceedings of the National Academy of Sciences offers a scientific first: a detailed snapshot of the terrible moments right after the Chicxulub impact — the most cataclysmic event known to have befallen life on Earth.

At a site called Tanis in North Dakota’s Hell Creek Formation, a team of paleontologists whose headquarters are at the University of Kansas unearthed a motherlode of exquisitely-preserved animal and fish fossils — creatures that lived in and around a deeply chiseled river connected to the ancient Western Interior Seaway — that were killed suddenly in events triggered by the Chicxulub impact.

The fossils were crammed into a “rapidly emplaced high-energy onshore surge deposit” along the KT boundary that contained associated ejecta and iridium impactite associated with the impact about 66 million years ago — an impact that eradicated about 75 percent of Earth’s animal and plant species.

field research with Robert DePalma at left and Peter Larson at right examining the site“A tangled mass of freshwater fish, terrestrial vertebrates, trees, branches, logs, marine ammonites and other marine creatures was all packed into this layer by the inland-directed surge,” said lead author Robert DePalma, a KU doctoral student in geology who works in the KU Biodiversity Institute and Natural History Museum. “Timing of the incoming ejecta spherules matched the calculated arrival times of seismic waves from the impact, suggesting that the impact could very well have triggered the surge.”

DePalma, who discovered the fossil motherlode, said the find outlines how the impact could have devastated areas very far from the crater quite rapidly.

“A tsunami would have taken at least 17 or more hours to reach the site from the crater, but seismic waves — and a subsequent surge — would have reached it in tens of minutes,” he said.

DePalma and his colleagues describe the rushing wave that shattered the Tanis site as a “seiche.”

“As the 2011 Tohoku earthquake in Japan showed us, seismic shaking can cause surges far from the epicenter,” he said. “In the Tohoku example, surges were triggered nearly 5,000 miles away in Norway just 30 minutes after impact. So, the KT impact could have caused similar surges in the right-sized bodies of water worldwide, giving the first rapid ‘bloody nose’ to those areas before any other form of aftermath could have reached them.”

According to KU researchers, even before the surge arrived, Acipenseriform fish (sturgeon) found at the site already had inhaled tiny spherules ejected from the Chicxulub impact.

micro-CT image showing cutaway of clay-altered ejecta spherule with internal core of unaltered impact glass“The fish were buried quickly, but not so quickly they didn’t have time to breathe the ejecta that was raining down to the river,” said co-author David Burnham, preparator of vertebrate paleontology at the KU Biodiversity Institute. “These fish weren’t bottom feeders, they breathed these in while swimming in the water column. We’re finding little pieces of ejecta in the gill rakers of these fish, the bony supports for the gills. We don’t know if some were killed by breathing this ejecta, too.”

The number and quality of preservation of the fossils at Tanis are such that Burnham dubs it the “lagerstätte” of the KT event — paleontologist-speak for a landmark sedimentary deposit with exceptionally intact specimens. He said this is especially true as the fish are cartilaginous, not bony, and are less prone to fossilization.

“The sedimentation happened so quickly everything is preserved in three dimensions — they’re not crushed,” Burnham said. “It’s like an avalanche that collapses almost like a liquid, then sets like concrete. They were killed pretty suddenly because of the violence of that water. We have one fish that hit a tree and was broken in half.”

Indeed, the Tanis site contains many hundreds of articulated ancient fossil fish killed by the Chicxulub impact’s aftereffects and is remarkable for the biodiversity it reveals alone.

“At least several appear to be new species, and the others are the best examples known of their kind,” DePalma said. “Before now, fewer than four were known from the Hell Creek, so the site was already magnificently significant. But we quickly recognized that the surrounding sediment was deposited by a sudden, massive rush of water, and that the surge was directed inland, away from an ancient nearby seaway. When we noticed asteroid impact debris within the sediment and a compact layer of KT boundary clay resting on top of it from the long-term fallout, we realized that this unusual site was right at the KT boundary.”

According to Burnham, the fossil trove fills a void in scientific knowledge with vivid new detail.

Researchers at the site posing: Jan Smit, Robert DePalma, Walter Alvarez and David Burnham wit a box core sample“We’ve understood that bad things happened right after the impact, but nobody’s found this kind of smoking-gun evidence,” he said. “People have said, ‘We get that this blast killed the dinosaurs, but why don’t we have dead bodies everywhere?’ Well, now we have bodies. They’re not dinosaurs, but I think those will eventually be found, too.”

DePalma said his find provides spectacular new detail to what is perhaps the most important event to ever affect life on Earth.

“It’s difficult not to get choked up and passionate about this topic,” he said. “We look at moment-by-moment records of one of the most notable impact events in Earth’s history. No other site has a record quite like that. And this particular event is tied directly to all of us — to every mammal on Earth, in fact. Because this is essentially where we inherited the planet. Nothing was the same after that impact. It became a planet of mammals rather than a planet of dinosaurs.

"As human beings, we descended from a lineage that literally survived in the ashes of what was once the glorious kingdom of the dinosaurs. And we’re the only species on the planet that has ever been capable of learning from such an event to the benefit of ourselves and every other organism in our world.”

At KU, DePalma and Burnham worked with Loren Gurche of the Biodiversity Institute. Other co-authors are Jan Smit and Klaudia Kuiper of VU University Amsterdam; Phillip Manning of the University of Manchester; Anton Oleinik of Florida Atlantic University; Peter Larson of the Black Hills Institute of Geological Research Inc.; Florentin Maurrasse of Florida International University; Johan Vellekoop of VU Leuven; and Mark A. Richards and Walter Alvarez of the University of California at Berkeley. 

-- by Brendan Lynch, KU News
Original KU News link 

Images: Top, intertangled mass of articulated fish from the Tanis inundation surge deposit. Middle top, Robert DePalma and Peter Larson conduct field research in Tanis. Middle bottom, micro-CT image showing cutaway of clay-altered ejecta spherule with internal core of unaltered impact glass. Bottom, researchers from left to right, Jan Smit, Robert DePalma, Walter Alvarez, David Burnham, with a collected box core sample of the KT boundary from Tanis. Images courtesy Robert DePalma.

Vertebrate Paleontology
Thursday, January 25, 2018

lizard Luperosaurus cumingii

A new paper appearing in Proceedings of the Royal Society B shows a varied collection of lizards throughout Asia to be unexpectedly close cousins of beach-dwelling mourning geckos, all descended from a common ancestor species that thrived along an ancient archipelago in the West Pacific that served as a “superhighway” of biodiversity.

The dispersal of these lizards, of the genus Lepidodactylus, touches upon a major theory of island biogeography developed by celebrated biologist E.O. Wilson, dubbed the “taxon cycle” model. The new paper also sheds light on lineage diversity and habitat use in the world’s most geologically complex insular region — Pacific island arcs spanning from the Philippines to Fiji.

“One of the things that I find exciting about this work is how our phylogeny, estimated from DNA sequence data, provides evidence for a giant, widespread radiation of variably sized mourning geckos, scaly-toed geckos and their relatives,” said co-author Rafe Brown, professor of ecology & evolutionary biology and senior curator at the KU Biodiversity Institute. “It was a big surprise to find groups of large-bodied, morphologically diverse, deep forest specialists, nested within a widespread clade of small-bodied coastal generalists — we didn’t think they were related at all.”

Brown said some of the mourning geckos’ closest relatives are physically very different, but all “conspicuously” live along island arcs or lost island arcs that have merged into continents, including the modern-day Philippines, northern and eastern New Guinea, eastern Melanesia, Vanuatu, Fiji, Christmas Island and Borneo.

Of 12 major Lepidodactylus lineages, interesting groups include a genus of obligate forest “slender gecko” species and two groups of mysterious “flap-legged” geckos endemic to the Philippines.

“The slender, long-bodied geckos of the genus Pseudogekko live deep in forests, and we didn’t think they were related to the small, primarily coastal scaly-toed geckos,” Brown said. “Another is Luperosaurus, the flap-legged geckos. They’re big and robust and have thorns and flaps all over their bodies, and some are orders of magnitude larger than mourning geckos. It’s astounding that these lizards that are so physically different have turned out to be close relatives.”

Brown’s collaborators included lead author Paul Oliver of Australian National University as well as Fred Kraus of the University of Michigan, Eric Rittmeyer of Rutgers University, Scott Travers of KU and Cameron Siler of the University of Oklahoma.

“To me, this work underscores how much we have yet to understand about the complexity of species diversification on our planet, particularly in island systems,” said Siler. “It is amazing to think about the role these ancient island systems played in the evolution of endemic communities in Wallacea, the West Pacific and Australasia.”

According to Brown, the findings were the result of extensive fieldwork among researchers as well as genetic analysis and data gleaned from biodiversity collections.

“No one research group could ever have put this together alone,” he said. “Firstly, we never knew these groups were closest relatives, and with separate research groups focusing on different regions with what we thought were unrelated lizard faunas, we might not have even put their DNA sequences into analyses together. The sheer magnitude of the sampling around New Guinea, Australasia, Borneo, Melanesia, Christmas Island, the Philippines and across the Pacific made this study possible. The key was putting together the efforts of many friends and colleagues who provided access to their samples and allowed us to paint the whole picture. Some of these lizards are super rare — there’s no way, in a single person’s career, could an individual go to all these places and collect all the necessary samples.”

Brown said the evolution of Lepidodactylus may be tied to the Vitiaz Arc, a near continuous chain of island arcs that stretched across the West Pacific some 30-40 million years ago during the Oligocene, which today is incorporated into present-day landforms ranging from the Philippines to Fiji.

“We used DNA sequencing data and sophisticated statistical analysis to estimate divergence of major groups in the phylogeny,” he said. “Those initial divergences probably date back to between 30 and 40 million years. When you scroll back into Earth’s history, the landmasses looked very different. One thing that jumps out is the inferred existence of a long chain of islands that stretched out across the Pacific called the Vitiaz Arc. This configuration of fragments of modern-day landmasses and islands that have since shifted but once lined up like a kind of superhighway for biodiversity across the Pacific. Given the timing, it seems like that big long chain of islands may have played a role in the evolution of this group.”

Brown said as the Vitiaz Arc fragmented and parts turned into the Philippines, Solomons, Fiji, Vanuatu and other islands that today are all very far apart, they may have facilitated the broad distribution of Lepidodactylus. 

“If ancient lineages evolved and gained widespread distribution across this ancient arc, some really may have persisted for the past 30 to 40 million years,” he said. 

The dispersal of the Lepidodactylus touches upon the model of the “taxon cycle” proposed by E.O. Wilson in his study of ants in Fiji and New Guinea. Wilson’s idea was that colonizer species are specialized to survive harsh island coastal terrains but eventually evolve traits to adapt to habitats away from island margins — more inland and upland — where some successor species thrive and others go extinct. In the meantime, the original costal colonizers often are replaced by successive waves of new invaders. 

“It’s a very famous, influential idea about how species may colonize new islands and habitats and possibly evolve through predictable ecological transitions,” Brown said. “The idea is very provocative because we commonly think about evolution as determined in part by chance, but what some components of species geographical range evolution were almost deterministic? The brilliance of E.O. Wilson was his ability to conceive of a cyclic process based solely on patterns he saw in ant species’ distributions. He didn’t have the phylogenies we have today, but he inferred relations and put this together as a very clear model, with predictions that we can test today with DNA, sophisticated statistics and knowledge of species’ distributions.”

According to Brown, findings in the new paper include support for the taxon cycle model in Lepidodactylus but also some evidence that runs counter to it. 

“In some cases, lizard lineages limited to continental fragments have persisted,” he said. “And in some cases, we did not find the most ancient lizards to be specialists from interior habitats on the oldest land masses. Some ancient lineages are found today on the margins of arc islands or just on the edges of larger landmasses. There are exceptions to any rule, of course. For instance, Lepidodactylus ranauensisis — a species that looks like the kind of common lizard that you might expect to find on a coconut tree on a beach in the Philippines—is actually endemic to Mount Kinabalu on Borneo, maybe 32 million years old, and has no close relatives. Perhaps it is the only surviving member of a once more diverse group of lineages that have gone extinct.  We just don’t know. But to find these single evolutionary relics is sort of exciting for a phylogeneticist.”

-- by Brendan Lynch, KU News

Photo: Luperosaurus cumingii is one species of unexpectedly related lizards inhabiting Asia. Credit: R.M. Brown

Herpetology
Thursday, October 5, 2017

LAWRENCE — There are precious few species today in the biodiversity hotspot of Madagascar that scientists can trace directly back to when all of Earth’s continents were joined together as part of the primeval supercontinent Pangea.

But a new study in the journal Scientific Reports suggests the Malagasy striped whirligig beetle Heterogyrus milloti is an ultra-rare survivor among contemporary species on Madagascar, boasting a genetic pedigree stretching back at least 206 million years to the late Triassic period. 

“This is unheard of for anything in Madagascar,” said lead author Grey Gustafson, a postdoctoral research fellow in ecology & evolutionary biology and affiliate of the Biodiversity Institute at the University of Kansas. “It’s the oldest lineage of any animal or plant known from Madagascar.”

Gustafson and his co-authors’ research compared the living striped whirligig found in Madagascar with extinct whirligig beetles from the fossil record. They then used a method called “tip dating” to reconstruct and date the family tree of whirligig beetles.

“You examine and code the morphology of extinct species the same as you would living species, and where that fossil occurs in time is where that tip of the tree ends,” he said. “That’s how you time their evolutionary relationships. We really wanted the fossils’ placement in the tree to be backed by analysis, so we could say these are the relatives of the striped whirligig as supported by analysis, not just that they looked similar.”

Gustafson noted one major hurdle for the team was the “painful” incompleteness of the fossil record for establishing all the places where relatives of the striped whirligig beetle once lived. 

“All of the fossils come from what is today Europe and Asia — we don’t have any deposits from Madagascar or Africa for this group of insects,” he said. “But they likely were very widespread.”

Today, whirligig beetles are a family of carnivorous aquatic beetles with about 1,000 known species dominated by members of a subfamily called the Gyrininae. But the Gyrininae are young upstarts compared with the striped whirligig beetle, the last remaining species of a group dominant during the time of the dinosaurs. This group according to Gustafson was decimated by the same asteroid impact that cut down the dinosaurs and caused the Cretaceous–Paleogene extinction event.

“The remoteness of Madagascar is what may have saved this beetle,” Gustafson said. “It’s the only place that still has the striped whirligig beetle because it was already isolated at the time of the Cretaceous–Paleogene extinction event — so the lineage was able to persist, and now it’s surviving in a marginal environment.”

Even today, the ageless striped whirligig beetle keeps its own company, preferring to skitter atop the surface of out-of-the-way forest streams in southeastern Madagascar — not mixing with latecomers of the subfamily Gyrininae who have become the dominant whirligig beetles on Madagascar and abroad. 

Indeed, Gustafson is one of the few researchers to locate them during a 2014 fieldwork excursion in Madagascar’s Ranomafana National Park.

“This one is pretty hard to find,” he said. “They like these really strange habitats that other whirligigs aren’t found in. We have video of them in a gulch in a mountain range clogged with branches and debris — there are striped whirligigs all over it.”

Unfortunately, the KU researcher said the remote habitats of the striped whirligig beetle in Malagasy national parks were threatened today by human activity on Madagascar.

“It’s a socioeconomic issue,” Gustafson said. “In the national park where first specimens of the striped whirligig beetle were discovered, there are local people who use the forest as a refuge for zebu cattle because they’re concerned about zebu being robbed. Their defecation can disturb the nutrient lode in aquatic ecosystems. Part of the problem is finding a way for local people to be able to make their livelihood while preserving natural ecosystems. But it’s a hard balance to strike. A lot of original forest cover also has been slashed and burned for rice-field patties to feed people.”

Gustafson hopes the primal origins of the striped whirligig beetle can draw attention to the need for protecting aquatic habitats while conceding that conservation efforts usually are aimed at bigger and more cuddly species, like Madagascar’s famous lemurs, tenrecs and other unique carnivorans.

“One of the things that invertebrate species suffer from is a lack of specific conservation efforts,” he said. “It’s usually trickle-down conservation where you find a charismatic vertebrate species to get protected areas started. But certain invertebrates will have different requirements, and right now invertebrate-specific conservation efforts are lacking. We propose the striped whirligig beetle would make for an excellent flagship species for conservation.”

- by Brendan M. Lynch, KU News

Photos, from the top: Gray Gustafson working in Madagascar; the striped whirligig beetle body and head; an illustration of a reconstruction of one of the Mesozoic whirligig beetles related to the striped whirligig examined in the study. All images courtesy Gray Gustafson.

Entomology
Thursday, October 5, 2017

I consider myself an avian taphonomist – a unique niche within the field of paleontology – as well as a science outreach specialist. I will first explain my research interests and then discuss my path to a career in science outreach.

In case the word is new to you, “taphonomy” is the study of what occurs between the death of an organism and its discovery as a fossil. I am interested in better understanding the circumstances that lead to differential preservation of avian skeletal elements, including depositional environment, scavenger activity, age- and gender-related effects, among other factors. Through my work, I try to explore what drives preservation biases in the fossil record of birds.

My research has mainly centered upon actualistic taphonomy experiments, which means that I conduct experiments with modern organisms and environs in order to make inferences about the past. For projects conducted via the University of Georgia (as a student) and via the University of Tennessee at Martin (as a faculty member), I collected humanely-killed chickens and ducks of known age, sex, and diet and put their carcasses out in different types of environments in different climate regimes. One thing that I was especially motivated to investigate was any role that medullary tissue might play in the preservation potential of avian leg bones. After the publication of Schweitzer and others in 2005 documenting possible soft-tissue preservation in a T. rex femur, I became fascinated by the concept of medullary tissue preservation. Medullary tissue is a reproductive-specific tissue in female birds that forms along the innermost layer of limb bones during the egg-laying cycle; it acts as calcium storage for production of the egg shell. Because it is formed rapidly and then utilized (broken down) rapidly, there is a net loss of calcium from females’ skeletal elements. Because of this, it might be expected that a gender-based preservation bias exists in the avian fossil record. In addition to this particular factor, my experiments have examined the roles of age (juvenile vs. adult), environment (habitat, temperature, humidity, pH, lithology, etc.), bacteria and fungi, and scavengers (including insects, invertebrates like crabs, and vertebrates like alligators, raccoons, and bobcats). Publications reporting my results are forthcoming! 

In 2016, a large review paper that my coauthors and I had been working on for about seven years was published. It morphed from a literature review for my thesis into a multivariable analysis of the roles of paleoclimate, environment, and bird body size in avian fossil preservation. It is my hope that the paper will inspire future avian taphonomy studies to improve collection of climate-related data. Understanding how climate change has impacted the avian fossil record could shed further light on questions about speciation and extinction of birds throughout time.

My other passion (and now my career) is science outreach and education. Throughout my undergraduate and graduate studies, I was involved in public outreach events with my universities, local nature centers and parks, and regional museums. After getting established in my first job – which was as a geology instructor at the University of Tennessee at Martin – I became motivated to engage underserved K-12 girls in the community and so I began leading a science-focused Girl Scout troop. My move in 2015 to the Florida Museum of Natural History brought me even further into the world of public outreach and education as the coordinator of a project funded by the National Science Foundation called FOSSIL: Fostering Opportunities for Synergistic STEM with Informal Learners. In this role, I’ve been able to help develop and lead paleontology workshops, foster connections between amateur and professional paleontologists across the world, and collaborate on science education research. (Learn more about FOSSIL by clicking here). Organizing opportunities for people to share with others their paleontology skills, experiences, and enthusiasm has been enormously rewarding. In mid-August of this year, I’ll be starting a new job with the University of Kansas Biodiversity Institute & Natural History Museum as their Outreach and Engagement Coordinator. I’m really excited about continuing to work with the public in a new capacity to foster a greater understanding of science and an appreciation for the Earth and its history.

Being creative, asking questions, and devising ways to get others excited about science (most often about paleontology) are all aspects of my jobs that I have loved. If you’re interested in pursuing a career in science, know that there are a wide variety of different positions and career paths, so keep your options open! Explore your curiosities and read, read, read as many peer-reviewed papers as possible.

- written for Time Scavengers 

Top Left: Examining Late Plestocene avian fossils in a cave on Royal Island, Bahamas

Bottom Right: Interacting with young visitors at the Aurora Fossil Festival in Aurora, North Carolina, as part of the FOSSIL Project

Museum Staff
Tuesday, October 3, 2017

LAWRENCE — Evolutionary biologists long have supposed that when species colonize new geographic regions they often develop new traits and adaptations to deal with their fresh surroundings. They branch from their ancestors and multiply in numbers of species.

Apparently, this isn’t the story of “true frogs.” The frog family scientists call Ranidae are found nearly everywhere in the world, and their family includes familiar amphibians like the American Bullfrog and the European common frog. 

New research from the University of Kansas appearing in Royal Society Biology Letters shows, in contrast to expectations, “the rapid global range expansion of true frogs was not associated with increased net-diversification.”

“First, we had to identify where these true frogs came from and when they started their dispersal all over the world,” said lead author Chan Kin Onn, a doctoral student at KU’s Biodiversity Institute. “We found a distinct pattern. The origin of these frogs was Indochina — on the map today, it’s most of mainland Asia, including Thailand, Vietnam, Cambodia and Burma. True frogs dispersed throughout every continent except Antarctica from there. That’s not a new idea. But we found that a lot of this dispersal happened during a short period of time — it was during the late Eocene, about 40 million years ago. That hadn’t really been identified, until now.”

Next, Chan and co-author Rafe Brown, curator-in-charge of the KU Biodiversity Institute’s Herpetology Division, looked to see if this rapid dispersal of true frogs worldwide triggered a matching eruption of speciation. 

“That was our expectation,” Chan said. “We thought they’d take off into all this new habitat and resources, with no competition — and boom, you’d have a lot of new species. But we found the exact opposite was true. In most of the groups, nothing happened. There was no increase in speciation. In one of the groups, diversification significantly slowed down. That was the reverse of what was expected.”

To establish the actual timing of true frogs’ diversification, Chan and Brown performed phylogenetic analysis of 402 genetic samples obtained from an online database called GenBank. These samples represented 292 of the known 380 true frog species in the world.

“We mined all of these sequences and combined them into a giant analysis of the whole family,” Chain said. “It is to my knowledge the most comprehensive Ranidae phylogenetic analysis ever performed that included most of the representative species from the family.” 

Chan and Brown focused on four genes that would help to establish the family tree of true frogs.

“It’s a genealogical pedigree of specimens, a family tree of species,” Chan said.  “Normally, you think of family tree as everyone in one family and how the various people are related. But this is more expanded where we look at how species are related to each other, so you can trace ancestry back in time.”

After completing the phylogenetic analysis, the KU researchers used several frog fossils to “time calibrate” the history of the frogs’ global dispersal.

“We use fossil frogs because we can accurately date the fossils,” Chan said. “We know we found the fossil in a certain rock deposit, and we know with confidence how old the deposit is, so then we can estimate the age of the fossil.”

After Chan and Brown deduced similarities between fossilized true frogs as reported by paleontologists and contemporary true frogs, they placed fossils into groups of closely related species, which scientists call genera.

“Using data from paleontological studies, we can loosely place a fossil where in the phylogeny it belongs and can put a time stamp on that point,” Chan said. “That’s where calibration happens, each fossil is sort of like an anchor point. You can imagine with a really big phylogeny, the more anchor points or calibration points the better your time estimate.”

Through this process, the KU researchers concluded true frogs didn’t become one of the most biodiverse frog families due to dispersing into new ranges, or due to filling a gap created by a catastrophic die-off (such as the Eocene-Oligocene Extinction Event that triggered widespread extinctions from marine invertebrates to mammals in Asia and Europe).

Rather, the rich diversity of species in the Ranidae family comes from millions of years’ worth of continual evolution influenced by a host of different environs.  

“Our conclusion is kind of anticlimactic, but it’s cool because it goes against expectations,” Chan said. “We show the reason for species richness was just a really steady accumulation of species through time — there wasn’t a big event that caused this family to diversify like crazy.”

- Brendan M. Lynch, KU News

Top image: KU researchers concluded true frogs didn’t become one of the most biodiverse frog family due to dispersing into new ranges, or due to filling a gap created by a catastrophic die-off. Rather, the rich diversity of species in the Ranidae family comes from millions of years’ worth of continual evolution influenced by a host of different environs. Image by R.M. Brown.
From top right: The Rana igorota; Sangirana tipanan; Spotted stream (an Asian true frog); another Asian true frog. Photos courtesy of Chan Kin Onn, a doctoral student at KU’s Biodiversity Institute.

Herpetology
Tuesday, October 3, 2017

LAWRENCE — Evolutionary biologists long have supposed that when species colonize new geographic regions they often develop new traits and adaptations to deal with their fresh surroundings. They branch from their ancestors and multiply in numbers of species.

Apparently, this isn’t the story of “true frogs.” The frog family scientists call Ranidae are found nearly everywhere in the world, and their family includes familiar amphibians like the American Bullfrog and the European common frog. 

New research from the University of Kansas appearing in Royal Society Biology Letters shows, in contrast to expectations, “the rapid global range expansion of true frogs was not associated with increased net-diversification.”

“First, we had to identify where these true frogs came from and when they started their dispersal all over the world,” said lead author Chan Kin Onn, a doctoral student at KU’s Biodiversity Institute. “We found a distinct pattern. The origin of these frogs was Indochina — on the map today, it’s most of mainland Asia, including Thailand, Vietnam, Cambodia and Burma. True frogs dispersed throughout every continent except Antarctica from there. That’s not a new idea. But we found that a lot of this dispersal happened during a short period of time — it was during the late Eocene, about 40 million years ago. That hadn’t really been identified, until now.”

Next, Chan and co-author Rafe Brown, curator-in-charge of the KU Biodiversity Institute’s Herpetology Division, looked to see if this rapid dispersal of true frogs worldwide triggered a matching eruption of speciation. 

“That was our expectation,” Chan said. “We thought they’d take off into all this new habitat and resources, with no competition — and boom, you’d have a lot of new species. But we found the exact opposite was true. In most of the groups, nothing happened. There was no increase in speciation. In one of the groups, diversification significantly slowed down. That was the reverse of what was expected.”

To establish the actual timing of true frogs’ diversification, Chan and Brown performed phylogenetic analysis of 402 genetic samples obtained from an online database called GenBank. These samples represented 292 of the known 380 true frog species in the world.

“We mined all of these sequences and combined them into a giant analysis of the whole family,” Chain said. “It is to my knowledge the most comprehensive Ranidae phylogenetic analysis ever performed that included most of the representative species from the family.” 

Chan and Brown focused on four genes that would help to establish the family tree of true frogs.

“It’s a genealogical pedigree of specimens, a family tree of species,” Chan said.  “Normally, you think of family tree as everyone in one family and how the various people are related. But this is more expanded where we look at how species are related to each other, so you can trace ancestry back in time.”

After completing the phylogenetic analysis, the KU researchers used several frog fossils to “time calibrate” the history of the frogs’ global dispersal.

“We use fossil frogs because we can accurately date the fossils,” Chan said. “We know we found the fossil in a certain rock deposit, and we know with confidence how old the deposit is, so then we can estimate the age of the fossil.”

After Chan and Brown deduced similarities between fossilized true frogs as reported by paleontologists and contemporary true frogs, they placed fossils into groups of closely related species, which scientists call genera.

“Using data from paleontological studies, we can loosely place a fossil where in the phylogeny it belongs and can put a time stamp on that point,” Chan said. “That’s where calibration happens, each fossil is sort of like an anchor point. You can imagine with a really big phylogeny, the more anchor points or calibration points the better your time estimate.”

Through this process, the KU researchers concluded true frogs didn’t become one of the most biodiverse frog families due to dispersing into new ranges, or due to filling a gap created by a catastrophic die-off (such as the Eocene-Oligocene Extinction Event that triggered widespread extinctions from marine invertebrates to mammals in Asia and Europe).

Rather, the rich diversity of species in the Ranidae family comes from millions of years’ worth of continual evolution influenced by a host of different environs.  

“Our conclusion is kind of anticlimactic, but it’s cool because it goes against expectations,” Chan said. “We show the reason for species richness was just a really steady accumulation of species through time — there wasn’t a big event that caused this family to diversify like crazy.”

- Brendan M. Lynch, KU News

Top image: KU researchers concluded true frogs didn’t become one of the most biodiverse frog family due to dispersing into new ranges, or due to filling a gap created by a catastrophic die-off. Rather, the rich diversity of species in the Ranidae family comes from millions of years’ worth of continual evolution influenced by a host of different environs. Image by R.M. Brown.
From top right: The Rana igorota; Sangirana tipanan; Spotted stream (an Asian true frog); another Asian true frog. Photos courtesy of Chan Kin Onn, a doctoral student at KU’s Biodiversity Institute.

Herpetology
Monday, October 2, 2017

LAWRENCE — Growing up around Havana, Javier Torres López always was fascinated by reptiles. As the son of a professor who teaches vertebrate zoology at the University of Havana, he focused on studies of literature and science in high school and thought about following in his father’s footsteps.

“In Cuba, everyone has an opportunity to go to university,” he said. “You have to take tests according to your preferred major, and you have the right to pick up to 10 majors. Based on the tests results and your high school score, you get one of the 10 options. I was able to obtain my first choice, biology. So, I started studying at the University of Havana as a biology major — that was in 2004. There, for the first time, I started to become aware of the diversity of Cuban and Caribbean amphibians and reptiles.”

As an undergraduate, Torres started conducting original research, finding himself drawn to Tropidophis, a genus of dwarf boa snakes endemic to the Caribbean and South America.

“I was totally into studying snakes,” Torres said. “I found out about this particular group of Cuban snakes called dwarf boas. Studying the behavior of those snakes got me a ticket to the Latin American Herpetology Congress held in Cuba in 2008.”

There, Torres had his first contact with Rich Glor, KU associate professor of ecology & evolutionary biology and associate curator at KU’s Biodiversity Institute. The two stayed in contact over the years as Torres completed his undergraduate studies. All the while, Torres continued to investigate species endemic to Cuba, spending time in the field and learning important lessons about research.

“After a while studying the behavior and biology of dwarf boas, I understood it was a difficult system to work with because they are quite rare and hard to find,” Torres said. “So, I started to work on a project to understand the distribution of diversity depending on the landscape. On this project, I started to study anoles, a group of diurnal lizards highly diversified in Cuba. It’s the richest island when we talk about anoles. In contrast to dwarf boas, they’re quite common, and you can find enough individuals to let you answer questions in ecology, evolution and conservation.”

Researching Cuban anoles, Torres earned his master’s degree by studying the consequences of hybridization among different anole species. He also spent several years teaching zoology and herpetology as an instructor at the University of Havana. While he contemplated earning a doctorate, he kept in touch with Glor at KU.

“While working on my master’s, I was reading Rich’s papers, and I really liked that our interests were alike,” Torres said. “So, I wrote to him and we started to exchange information. I came to the U.S., and he came to Cuba. Finally, I applied here and I am following Ph.D. studies in the same vein as my master’s, with a side project on Tropidophis.”

Now at KU, Torres holds his Cuban citizenship and makes return visits to his home island. 

He maintains strong ties with his professional colleagues in Cuba, where he continues to advise students at the University of Havana. He also recently submitted a grant to National Geographic to fund several major field expeditions back to Cuba.

Indeed, Torres is already making vital contributions to herpetological research at KU. He has donated a major collection of tissue samples of reptile species endemic to Cuba to KU’s Biodiversity Institute. The valuable material can be used by current and future researchers interested in Cuban and Caribbean herpetology.

“When I traveled here to start my Ph.D., I brought 400 tissue samples of Cuban reptiles, and last month I went home to Cuba and brought back about 600 more samples — now the Biodiversity Institute has about 1,000 samples of 63 Cuban species, mostly reptiles, and most of them are endemic,” Torres said. “I would say the KU Biodiversity Institute harbors one of the most important tissue collections of Cuban reptiles. A tissue sample is the raw material for conducting genetic studies. There is a lot of things you can do with genetics, but there is a major concern in evolutionary biology which genetics allows us to understand better — how and why new species arise. From that number of samples, you can think of several projects involving the study of the DNA.”

Moreover, Torres and Glor traveled this summer to Cuba, where they worked on preparation of 760 whole specimens for eventual transport to KU. “The plan is to bring those back the next time I travel to Cuba,” Torres said.

“This will be the most important collection of Cuban reptiles brought to the United States in the past 20 years and includes lots of rare Cuban endemics,” Glor said.

Studying in the U.S. has some major advantages over the choices and technologies made available at Cuban universities, according to Torres.

“Here, it is easier to build your preferred curriculum because there are more options of classes — in Cuba, you have more mandatory and less optional classes. But the largest difference is in the area of resources. In Cuba, we have a great theoretical program, but when you have to do labwork, we don’t have all necessary tools and equipment and we have to search for alternatives. So basically, here there’s better availability of textbooks, journals, internet and technology.

“I feel very pleased and very lucky to be here in at the Biodiversity Institute,” he said. “Particularly the herpetology division here at KU is a great group to be with. For me, the first months were tough, but thanks to the help I found in my adviser, fellow students and other researchers at the herpetology division (and the BI in general) I made it through.”

That said, Torres finds himself missing many of the most important aspects of home. Most of all, Torres misses his family and girlfriend. “I don’t have to think about answering that,” he said.  

But he also finds himself craving Cuban home cooking.

“I’m planning to go home in December to spend New Year’s Eve in Cuba,” Torres said. “It is a tradition in there to spend it with family eating roast pork, rice, beans, yucca, fried plantain and salad. I love this town, but Cuban cuisine is different from what you find in Lawrence. I don’t think there’s an authentic Cuban restaurant. I had a Cuban sandwich here — it was very good, but it wasn’t Cuban.”

Photos (courtesy of Javier Torres López):

Top left: Relocating a group of giant tropes (Tropidophis melanurus) found in a risky area.

Bottom right: The largest toad in Cuba, Peltophryne fustiger, is quite common in the west.

- Brendan M. Lynch, KU News

Herpetology
Monday, October 2, 2017

After 114 years of guarding Dyche Hall on the University of Kansas campus, four of the eight statues that decorated the exterior of the building were removed Sept. 1.
 
Referred to as grotesques, the limestone statues are carved fantastical animals, with various animal characteristics merged together and incorporated with KU paraphernalia. Mixtures of lions, goats, dogs, cats, elephants and jackals make up the figures, but some characteristics have eroded due to exposure of the Kansas climate since 1903.

“Each is a work of art created by Joseph Frazee at the turn of last century,” said Leonard Krishtalka, director of the KU Biodiversity Institute and Natural History Museum in a news release. “They are a unique mythological menagerie created specifically to honor Kansas and KU. They have suffered more than 100 years of Kansas wind, sun, snow and rain, and we are committed to replacing them with new hand-carved replicas.”

The four statues — about 3 feet tall — are now situated in their new home, in the Panorama Gallery of the KU Natural History Museum. Two of the states have been encased in Plexiglas and are visible to the public, while the other two are still encapsulated in plastic wrap to protect them from further damage, explained Jen Humphrey, Director of External Affairs for the history museum.

The museum plans to raise funds to hire an artist to replace each of the grotesques with carved replicas, as the originals can’t be repaired. The removal of the grotesques is part of a $4.2 million renovation funded by the state of Kansas. It will clean and repair the exterior stonework of Dyche Hall, replace the roof, windows and all internal walls, and install a new HVAC system for the seventh floor of the 1903 building. It will also restore the seventh floor to its original splendor, Krishtalka said.

The seventh floor of Dyche is home to thousands of mammal and bird specimens, and it houses the research offices and laboratories of KU Biodiversity Institute graduate students and scientists. Once completed in February 2018, the environment on the seventh floor will conform to established conservation standards that are ideal for study and housing of the research collections.

Bids for carving new grotesques are forthcoming, the news release stated, which will also determine the amount the university is also hoping to fundraise, in addition to the renovation.

Four additional grotesques on the east side of Dyche Hall will be removed later this fall and added to those on display in the museum. Humphrey explained that once the renovation is complete on the west and south side of the building, the scaffolding will be moved to the north and east side where the sculptures will be removed.

To support the fund for recreating the grotesques, visit the Biodiversity Institute website.

- Savanna Maue, The Topeka Capital-Journal 

Natural History Museum
Monday, October 2, 2017

The interplay between range expansion and concomitant diversification is of fundamental interest to evolutionary biologists, particularly when linked to intercontinental dispersal and/or large scale extinctions. The evolutionary history of true frogs has been characterized by circumglobal range expansion. As a lineage that survived the Eocene–Oligocene extinction event (EOEE), the group provides an ideal system to test the prediction that range expansion triggers increased net diversification. We constructed the most densely sampled, time-calibrated phylogeny to date in order to: (i) characterize tempo and patterns of diversification; (ii) assess the impact of the EOEE; and (iii) test the hypothesis that range expansion was followed by increased net diversification. We show that late Eocene colonization of novel biogeographic regions was not affected by the EOEE and surprisingly, global expansion was not followed by increased net diversification. On the contrary, the diversification rate declined or did not shift following geographical expansion. Thus, the diversification history of true frogs contradicts the prevailing expectation that amphibian net diversification accelerated towards the present or increased following range expansion. Rather, our results demonstrate that despite their dynamic biogeographic history, true frogs diversified at a relatively constantly rate, even as they colonized the major land masses of Earth.

Check out the study titled “Did true frogs ‘dispersify’?” here

Herpetology
Monday, October 2, 2017

The interplay between range expansion and concomitant diversification is of fundamental interest to evolutionary biologists, particularly when linked to intercontinental dispersal and/or large scale extinctions. The evolutionary history of true frogs has been characterized by circumglobal range expansion. As a lineage that survived the Eocene–Oligocene extinction event (EOEE), the group provides an ideal system to test the prediction that range expansion triggers increased net diversification. We constructed the most densely sampled, time-calibrated phylogeny to date in order to: (i) characterize tempo and patterns of diversification; (ii) assess the impact of the EOEE; and (iii) test the hypothesis that range expansion was followed by increased net diversification. We show that late Eocene colonization of novel biogeographic regions was not affected by the EOEE and surprisingly, global expansion was not followed by increased net diversification. On the contrary, the diversification rate declined or did not shift following geographical expansion. Thus, the diversification history of true frogs contradicts the prevailing expectation that amphibian net diversification accelerated towards the present or increased following range expansion. Rather, our results demonstrate that despite their dynamic biogeographic history, true frogs diversified at a relatively constantly rate, even as they colonized the major land masses of Earth.

Check out the study titled “Did true frogs ‘dispersify’?” here

Herpetology