Author: Jonathan Losos Page 13 of 129

Professor of Biology and Director of the Living Earth Collaborative at Washington University in Saint Louis. I've spent my entire professional career studying anoles and have discovered that the more I learn about anoles, the more I realize I don't know.

A remote island in the Caribbean could offer clues as to how invasive species are able to colonise new territories and then thrive in them, a new study suggests.

Scientists from the University of Plymouth have recently completed extensive research into a lizard population on the Cayman Islands.

Up until the mid-1980s, there had never been a recorded sighting of the Maynard’s Anole (Anolis maynardi) on Cayman Brac island despite it being less than 10km from its native territory, Little Cayman.

However, since the species was first discovered on Cayman Brac in 1987 – in what is thought to have been a human-assisted colonisation – its population has spread right across the 39km² island.

For this study, recent graduate Vaughn Bodden and Lecturer in Conservation Biology Dr Robert Puschendorf conducted a detailed analysis of the invasive species.

They wanted to assess whether individuals at the forefront of the invasion have developed distinct biological traits that are advantageous for dispersal, and compared their findings to animals in the area of first introduction and the native population on Little Cayman.

They discovered the Cayman Brac population has diverged morphologically from the native population, and within the invasive range there was trend of increasing forelimb length from the core to range edge areas. This ran contrary to the expected findings that longer hindlimbs would be the trait selected as a dispersal-related phenotype.

They also showed that the introduced population had lower levels of parasite prevalence, and that both males and females were of significantly higher body condition than the native population.

Writing in the Journal of Zoology, they say the results are a perfect example of how a species can colonise a new territory, and the biological adaptations it can make in order to do so.

Vaughn, who graduated with a First from the BSc (Hons) Conservation Biologyprogramme in 2018, said:

“There has been a history of lizard studies indicating that longer hindlimbs are an important factor affecting movement ability, so to not find longer hind limbed animals on the range edge was a surprise. For parasites, we found a clear decreasing trend in prevalence within the invasive population from the area of first introduction to the range edge, indicating that the parasites lag behind the host during periods of range expansion.

“We think our findings add to the growing body of literature that demonstrates the complex dynamics of species’ invasions. The results highlight that the animals on the range edge of an invasion are likely to be experiencing different ecological selection pressures that can result in changes in behaviour, morphology, and health for the animals.”

Dr Puschendorf has spent several years researching the consequences of emerging infectious diseases and climate change on biodiversity, with a particular focus on Central America. He added:

“Biological invasions are an important conservation threat across the world. However, every invasion needs to be carefully investigated to identify impacts to native eco-systems and identify potential mitigation strategies.

“In this instance there is likely to be limited overlap with, and therefore a limited threat to, the endemic anole population – the Cayman Brac Anole (Anolis luteosignifer) – because one inhabit the crowns of trees while the other is found closer to the ground. This in some ways highlights the challenges biodiversity managers face when managing species invasions with limited resources, and emphasises the need for greater collaboration among scientific and policy communities.”

Effects of Introduced Brown Anoles on the Native Anole of Grand Cayman

By Jonathan Losos

On April 9, 2019

In All Posts

Inbar Maayan tells all about her ongoing work in the cover story of this month’s issue of Flicker, the bimonthly bulletin of the Cayman Islands Department of Environment’s Terrestrial Resources Unit. Check it out, and also read about Caymanian fossils and the massive effort to eradicate invasive green iguanas (half a million and counting!).

The Science of Species Delimitation: David Hillis Diagnoses What’s Being Done Right and Where the Field Is Headed

By Jonathan Losos

On March 3, 2019

In All Posts

In a somewhat autobiographical romp through the history of species delimitation, David Hillis, in a recently published article in the Journal of Herpetology, details the state-of-the-field in terms of phylogenetic and species delimitation, detailing both the many advances that have been made over the last few decades, but also pointing out where things are out of whack and need some recalibration. There’s much more to the article than the figure above, but that’s a good place to start!

Effects of Deforestation on Lizard Communities Differ at Low and High Elevations

By Jonathan Losos

On February 27, 2019

In All Posts

Anolis landestoyi. Photo by Miguel Landestoy.

As reported by Science Daily:

Elevation matters when it comes to climate change, deforestation and species survival

Date:: February 25, 2019
Source:: University of Toronto
Summary:: A study examining the impact of deforestation on lizard communities in the Dominican Republic demonstrates differing outcomes at different elevations. In the lowlands, deforestation reduces the number of individuals, but not which species occur in an area. In the highlands, it’s the opposite. When the forest is cut down at higher elevations, the newly created pastures become filled with species found in the warmer lowlands. But locally adapted mountain lizards cannot survive as temperature rises.

University of Toronto student George Sandler was shocked to see the rainforest floor suddenly come to life around him, as if in a scene from an Indiana Jones movie.

“The forest floor started rustling around me,” says Sandler, “as dozens of crabs emerged from holes and crevices. Some were huge, the size of dinner plates. I even spotted a hermit crab climbing up a tree, lugging its heavy shell along with it.”

But Sandler wasn’t in the field to study crabs. He was in the Dominican Republic to take a census of the region’s Anolis lizard species for a study on the effects of deforestation being conducted by researchers Luke Mahler, Luke Frishkoff and collaborators. In the Caribbean nation, deforestation is the main form of natural habitat loss as residents cut down rainforest in order to produce charcoal, as well as create pastures for livestock and farmland for crops.

It is no surprise that deforestation has a profound effect on biodiversity; scientists have been studying this problem around the globe for decades. What is surprising is the difficulty they still face in making detailed predictions about which species survive, especially in relation to other factors such as climate change and natural local conditions.

Now, using the data collected in the census, the research team has discovered details about how Anolis lizards are being affected by the loss of their habitat.

“When it comes to predicting the effects of deforestation,” says Mahler, “elevation matters.”

Mahler is an assistant professor in the Department of Ecology & Evolutionary Biology (EEB) in the Faculty of Arts & Science at the University of Toronto. Frishkoff led the research while he was a postdoctoral fellow in Mahler’s lab at U of T and is lead author of the paper describing their findings, published today in Nature Ecology & Evolution; he is currently an assistant professor at the University of Texas at Arlington. Sandler and researchers from the National Museum of Natural History in Santo Domingo were also co-authors.

Mahler and Frishkoff analyzed populations of lizards in both lowland and highland regions affected by deforestation. Generally, the lowlands are warmer than the highlands due to altitude; also, forest canopy blocks direct sunlight, making forests at any altitude cooler than their immediate surroundings.

“It turns out that deforestation changes lizard communities in fundamentally different ways in the lowlands as compared to the highlands,” says Mahler. “In the lowlands, deforestation reduces the number of individuals, but not which species occur in an area. In the highlands, it’s the opposite.”

“When the forest is cut down at higher elevations,” says Frishkoff, “the newly created high elevation pastures become filled with species we saw down in the warmer lowlands. But, the locally adapted mountain lizards cannot survive.”

The invasion into the highlands by lowland-dwelling lizards was made possible by a combination of human activity and natural factors; i.e. deforestation and elevation respectively. Thanks to the altitude, the temperature of deforested fields in the highlands was comparable to the temperature of forested lowlands.

As it is in many regions around the world, the problem of deforestation in the Dominican Republic is dire. In 2016, Mahler announced the discovery of a previously unknown chameleon-like Anolis lizard on the island of Hispaniola. In the paper describing the discovery, Mahler and his co-authors recommended that the new species, dubbed Anolis landestoyi, be immediately classified as critically endangered because the lizard was threatened by illegal clear-cutting in the region.

Unlike the crabs that crowded around Sandler in the rainforest, the lizards were more elusive and difficult to survey. In order to obtain accurate counts, the students employed a technique known as mark-resight.

“We hiked out to our designated plots,” says Sandler, who was an undergraduate student while conducting the field work and is currently an EEB graduate student at U of T. “Then we walked around looking for lizards. We carried a paint spray gun filled with a non-toxic, water soluble paint — a different colour for each of the six observation periods. If we saw a lizard we would note the species, if it had any paint on it already, and the colour of the paint. Then we would spray the lizard with the paint gun we were carrying, a task that was a little tricky with some of the more skittish species!”

Paint on a lizard indicated that it had already been counted; and the number of unpainted lizards that were observed during each period allowed the researchers to calculate how many lizards were going uncounted.

“It’s not your typical summer job,” says Mahler. “Each survey is essentially a game in which you try to find all the lizards in an area and zap them with paint. It’s a messy affair, but we get great data from it.”

“Our results help us better understand the likely consequences of climate change and how it will interact with human land-use,” says Frishkoff.

For lowland forest Anolis lizards, deforestation just means a decline in abundance or relocating to the highlands. But for highland species, the situation is more critical. Unlike their lowland cousins, they have reached high ground already and in the face of deforestation have nowhere to go — a situation facing more and more species around the world.

“Our data suggest that while many lowland Anolis species might not be seriously affected by deforestation and the gradual warming brought about by climate change,” says Frishkoff, “the opposite is true for the unique mountain lizard species which do not tolerate land-use change well, and which are already on the top of the island.

“Land-use and climate change are a double whammy for these species. If we cut down the mountain forests these lizards have nowhere left to go. Gradual warming might push species up slope, but when you’re already at the top of the mountain, you can’t move any higher.”

Story Source:

Materials provided by University of Toronto. Note: Content may be edited for style and length.

Journal Reference:

Luke O. Frishkoff, Eveling Gabot, George Sandler, Cristian Marte, D. Luke Mahler. Elevation shapes the reassembly of Anthropocene lizard communities. Nature Ecology & Evolution, 2019; DOI: 10.1038/s41559-019-0819-0

Remembering Lourdes Rodriguez Schettino

By Jonathan Losos

On February 24, 2019

In All Posts

Lourdes Rodriguez Schettino with Ada Chamizo and Rich Glor in 1999.

Our recent mention of Richard Etheridge’s death reminded us that we’d never noted the passing of Lourdes Rodriguez Schettino nearly two years ago, in March of 2017.

Lourdes was an expert on the lizards of Cuba, particularly the iguanid lizards, about which she truly wrote the book. She also was the lead author on a lovely book on Cuban herpetology (below).

Sadly, I am unaware of any obituaries of Lourdes in English, but the Instituto de Ecología y Sistemática, where she worked for many years, has a nice summary of her life’s work, and there is a brief notice in Revista Colombiana de Ciencia Animal.

Lourdes Rodriguez Schettino in 1995.

Richard Etheridge, Founder of Anole Systematics, Passes Away

By Jonathan Losos

On February 21, 2019

In All Posts

Word has belatedly reached Anole Annals’ ears that, sadly, Richard Etheridge passed away last month at the age of 89. Richard was not only a titan of lizard systematics, but the founder of anole systematics. Amazingly, the classic worked that is the foundation of all that has followed in anole systematics was his never-published PhD dissertation. Bobby Espinoza and Kevin de Queiroz wrote a biography of Richard’s career that was published a decade ago in Copeia and that, happily, is freely available.

New Research Project on Anolis pogus on St. Maarten

By Jonathan Losos

On February 5, 2019

In All Posts

This just in from the Daily Herald, the self-proclaimed leading for St. Maarten and the northeastern Caribbean:

Research ongoing on status of endemic Bearded Anole Lizard

Bearded anole with a dorsal stripe, dark bands and a turquoise spot around the eyes foraging on St. Maarten. (Joost Merjenburgh photo)

COLE BAY–Nature Foundation, in collaboration with Reptile, Amphibian and Fish Conservation Netherlands RAVON, is researching the local status of the bearded anole (Anolis pogus) lizard, also known as the Anguilla Bank bush anole.

This new research, executed by Aeres University student Joost Merjenburgh, will provide insight into the status of the vulnerable species and hopefully prevent its extinction.The bearded anole is an important endemic species to St. Maarten, which means that the species is native and can only be found here. In the past, the bearded anole occurred on Anguilla and possibly on Saint-Barthélemy, but has vanished on both islands for unknown reasons.

The research is aimed to better understand the current abundance, distribution and habitat preference of the bearded anole, as presently only little data is available. The data will provide insight about the population trend of the species and are needed for its International Union for Conservation of Nature (IUCN) red-list re-assessment. With this information measures can be made to conserve and protect the species.

Merjenburgh is investigating a total of 100 80-square-metre location plots each. All bearded anole are counted and measurements are taken of tree canopy cover and habitat type. Until now the bearded anole population seems to be well distributed on the island. The bearded anole seems to be quite abundant when searching in the right habitat and is mostly absent in residential areas.

Bearded anoles have a special appearance which can differ between individuals. Some individuals have a turquoise-coloured spot around the eye, others have a dorsal stripe or dark bands across the neck and body, and some have all characteristics. The reason there is so much difference in pattern and coloration is that they use their appearance for camouflage and communication purposes.

The bearded anole can also use the dewlap, a flap of skin that hangs beneath the lower jaw, to communicate. Although both genders have a dewlap, the one on the female is usually much smaller and less colourful than the one on the male. The male extends his dewlap mainly to attract females during mating season or to confront other males when they enter his territory, explained Merjenburgh.

Their diet, like other anoles, consists mainly of small arthropods – for example, cockroaches, crickets and spiders are their favourite foods – and occasionally flowers and fruits.

This species also falls prey to predators sometimes. One of those predators is the mongoose, which is an introduced species. The mongoose eats every native reptile species on the island and is probably the reason the only native snake, the leeward island racer, has probably become extinct on St. Maarten, said Merjenburgh.

New Book on Lizard Behavior Appears Next Month

By Jonathan Losos

On January 25, 2019

In All Posts

Name that cover-gracing anole!

A new book on lizard behavior has an anole gracing the cover (who can guess the species?) and an all-star cast of contributors, including a number familiar to AA faithful (see Table of Contents below). The book is due out in a month, but you can go ahead and pre-order it. Sadly, it’s priced in the stratosphere: $159 for the 400 page volume. Let’s hope for a paperback edition!

AA Greatest Hits: A Highly Anecdotal Account of a Most Remarkable Anole

By Jonathan Losos

On January 21, 2019

In All Posts

From the archives. One of the greatest <i>Anole Annals</i> posts of all times, because why not?

“You’ve gotta see this!” my fiancé Mark called to me one morning. He was outside, which could mean only one thing: a wildlife encounter was underway. Living in a semi-rural neighborhood in Florida, you never knew what you would see, from a mated pair of Sandhill Cranes walking down the street with their young, to Gopher Tortoises excavating burrows in the front yard.

I walked downstairs to the concrete area under our elevated house where Mark was staring at something on the ground. I looked down to see a frog (Cuban Treefrog) with the tail of an A. carolinensis protruding from its gullet.

“I knew that lizard,” Mark said forlornly.