Biological changes among invasive species

Date:  April 8, 2019

Source:  University of Plymouth

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.

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After Last Year's Hurricanes, Caribbean Lizards Are Better at Holding on for Dear Life - via Herp Digest

A stunning case of natural selection in action

Ed Young, 7/25/18

The lizards didn’t see the hurricanes coming. Neither did Colin Donihue.

Last summer, Donihue, a researcher from Harvard University, traveled to the Caribbean islands of Turks and Caicos to study a local species of anole lizard. Conservationists were set to exterminate rats that had been introduced to the two islands to preserve their native wildlife, and Donihue wanted to see how the lizards might evolve once the rodents were gone. He and his colleagues captured dozens, and measured their bodies, legs, and toes. Then, in early September, they packed up and flew home, with a vague plan to return in a few years and measure the lizards again.

Four days later, Hurricane Irma arrived. It battered Turks and Caicos with 165-mph winds that created 20-foot waves, destroyed homes, snapped power lines, and killed at least 14 people. Two weeks later, Hurricane Maria delivered a second blow, only slightly less powerful than Irma’s.

Donihue and his team realized that they had a rare chance to see how natural disasters change the evolutionary fate of a group of animals. After all, they had been the last to observe the anoles before the hurricanes struck. So in October, they flew back to the islands.

I wasn’t really sure what to expect,” Donihue says. 

He found that the islands had clearly taken a severe hit, but were also rebounding quickly. Many trees had been uprooted and stripped bare, but those that had survived were already putting out new leaves. And among the fresh greenery, there were anoles.

The lizards can be found throughout the Caribbean, clinging to twigs and tree trunks with their sticky toes. Whenever Donihue spotted the lizards, he would lasso them with loops of string at the end of modified fishing poles. (“It doesn’t hurt them, because they have very strong neck muscles,” he says. “It’s much easier than running up and grabbing them with your hands.”)

“To be honest, given how catastrophic hurricanes are, I thought it was plausible that survival would be random—that there wouldn’t be an advantage that would help [the lizards] survive,” he says. But when he compared the survivors’ measurements with those of the pre-hurricane population, he realized he was wrong.

He found that, on average, the post-hurricane lizards had toe pads that were 6 to 9 percent bigger than those of pre-hurricane individuals, and front legs that were 2 percent longer. This wasn’t because the bodies of specific lizards had changed; there’s no evidence that the toes of adult anoles can grow by that amount. Instead, the storms had simply wiped out all the lizards with small toe pads. By selecting for individuals that were better at clinging to surfaces—and presumably at withstanding high winds—the storms had changed the average proportions of the population.

These sound like small changes, but natural selection famously works on small physical variations, favoring some over others across many generations. “The changes were subtle, and we couldn’t have noticed them just by holding the lizards in our hands,” Donihue says. “But they were consistent between the two island populations, which makes us feel more confident that this wasn’t a fluke.” The variation in the toe and leg measurements narrowed after the storms, too, adding further evidence that the hurricanes had selected for lizards with particular kinds of bodies.

But one trend didn’t make sense: After the hurricanes, the average length of the lizards’ hind legs was 6 percent shorter than before—the opposite pattern from their front legs. “This was a real head-scratcher,” Donihue says.

He and his colleagues worked out what had happened by placing the lizards on small wooden posts and subjecting them to gusts from “the largest leaf blower we could find,” he says. The lizards would shimmy to the sheltered side of the posts, tuck their front legs close to their bodies, and cling for dear life. But because of the way their legs are structured, their hind thighs would always jut out. These exposed thighs caught the wind like sails, and would eventually rip the lizards from their secure footing (and into the safety nets the team had set up).

Once the team realized this, everything clicked into place. “With shorter thighs, you’re catching less wind,” Donihue says.

“This is a striking case of rapid evolution, which, as we can see here, can proceed exceedingly fast, even within a generation,” says Carol Lee, who works at the Center for Rapid Evolution at the University of Wisconsin at Madison. “I expect there will be many more cases like this in the future, where catastrophic events impose strong selection on populations, and where populations will need to evolve or go extinct.”

For decades, Donihue’s colleagues, led by Jonathan Losos, have been documenting many examples of external threats quickly shaping the evolution of anoles. They’ve shown that some species evolved longer legs to better flee from invasive predators that were introduced to their islands. They’ve found that other anoles evolved larger toe pads to more effectively climb onto higher branches when new competitors drove them out of their usual low-lying habitats.

The team has also found examples of natural selection imposed by natural disasters. In 1998, they showed that over a 20-year period, anoles in the Bahamas tended to have longer legs in the months or years after hurricanes had hit. And just last year, they found that the extreme winter that hit the southern United States in late 2013 selected for Texan anoles that were more tolerant of the cold.

No one knows what will happen to the Texan anoles, or those in Turks and Caicos, in the long run. Now that the hurricanes have passed, the lizards are probably facing the same evolutionary pressures that they faced before, which might push their proportions back to baseline levels. Then again, another hurricane season looms. If these storms  mirror the severity of those in 2017, they might continue to direct the evolutionary fates of the anoles—and other Caribbean animals.

“I think we’ll find more and more of these studies coming out, since extreme climate events are becoming more frequent and more severe,” Donihue says. “Again and again, we’re seeing that these extreme events can have an evolutionary impact.”

Humans Doomed Caribbean's 'Lost World' of Ancient Mammals

By Mindy Weisberger, Senior Writer | November 7, 2017 06:40am ET

Thousands of years ago, the forests of the Caribbean islands hosted more than 130 species of diverse mammal life, ranging from sloths and giant monkeys to mammoths and oversize rats. But all that changed after humans showed up, around 6,000 years ago.

After humans began populating islands in the Caribbean, native mammal species began to vanish from the region, according to the fossil record. Today, mammal diversity in the Caribbean is far lower than it was during the time after the last ice age, with only 60 bat species and 13 nonflying mammal species remaining. The story of when dozens of mammal species went extinct is written in fossils, but why they died out has been challenging for scientists to pinpoint.

However, a recent study that analyzed extensive geological evidence alongside records of human migration revealed that two waves of humans settling in the Caribbean — first from the Americas, and then from Europe — dealt a one-two punch to native wildlife and were chiefly responsible for driving so many Caribbean mammal species to extinction. [Wipe Out: History's Most Mysterious Extinctions]

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Discovery: Bernie Sanders spider

Date: September 26, 2017

Source: University of Vermont

A scientist at the University of Vermont and four of his undergraduate students have discovered 15 new species of "smiley-faced" spiders -- and named them after, among others, David Attenborough, Barack Obama, Michelle Obama, Leonardo DiCaprio, and Vermont Senator Bernie Sanders.

You won't find them in Washington, DC, Hollywood, or Vermont -- but on Caribbean islands and other southern spots you might now get a glimpse of Spintharus davidattenboroughi, S. barackobamai, S. michelleobamaae, and S. berniesandersi as well as S. davidbowiei and S. leonardodicaprioi.

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Caribbean Anoles Function as Model Organisms for Evolutionary Dynamics – via Herp Digest

The small lizards (Anoles) adapted to unique niches among dozens of Caribbean isles.

By Amber Dance, The Scientist, January 1, 2017

It’s not easy to snare a lizard. Evolutionary biologist Michele Johnson affixes a noose made of dental floss to a telescopic fishing rod to reach into the bushes and tree canopies where Caribbean anoles live. By the end of the summer field season, her students from Trinity University in San Antonio, Texas, develop a knack for it. “We almost always catch our lizards,” says Johnson.

She doesn’t just collect field measurements and observations; she’s taken 30 different species of anoles back to her lab to analyze their physiology. Anoles have become a favorite model for evolutionary biologists because of their extraordinary diversity—there are more than 400 species in genus Anolis—and because of how they originally populated the Caribbean islands. The relative scarcity of mammals, snakes, or birds on the islands left many niches open for the lizards to occupy.

As anoles—which also inhabit Central and South America—reached individual islands, their populations diversified into island-specific forms that occupy certain niches. For example, each of the four largest islands in the Greater Antilles (Hispaniola, Cuba, Puerto Rico, and Jamaica) hosts one or more species that are green lizards hanging out in the lower canopies of trees, and another group of short-limbed, slow-moving reptiles that perch on twigs. These are two of the six “ecomorphs” that scientists who study Caribbean anole species have defined. To be considered an ecomorph, a set of habitat specialists must exist on more than one island, though the species in each group differ between islands. And yet, other anole species belong to no particular ecomorph class.

Caribbean anoles offer scientists a sort of “natural experiment,” explains Luke Mahler, an evolutionary biologist and herpetologist at the University of Toronto. Each isle, with similar environments, acts as a replicate for how anoles underwent convergent evolution into ecomorphs. As a result, evolutionary studies of anoles have flourished in the past couple of decades—think Darwin’s finches, but scalier.

“They really are a good model system for lots of questions, from very small-scale molecular work all the way up to adaptive radiation,” says Jerry Husak, a physiologist at the University of St. Thomas in St. Paul, Minnesota.

The basic anole ecomorphs go way back in evolutionary history, found Jonathan Losos, an evolutionary ecologist at Harvard University. Emma Sherratt, now at Australian National University in Canberra, got a hold of 20 fossil anoles while a postdoc in Losos’s lab. The fossils dated back 15 million to 20 million years, when the lizards were preserved in amber on the island of Hispaniola. Some were in museums, others in private collections. Using CT scans, the Losos team examined anatomy to confidently assign these fossils to four of today’s ecomorphs; a couple other fossils might be part of a fifth (PNAS, 112:9961-66, 2015). “At least several of the habitat specialist types already existed,” concludes Losos.

Despite the countless hours biologists have spent studying Caribbean anoles, the genus seems to have plenty of surprises still in store. In addition to her ongoing studies of physiology and behavior in diverse anole species, Johnson has recently focused on how her local Texan anole, Anolis carolinensis, determines dominance. A. carolinensis, like many other anole species, adopts a strict mating hierarchy in captivity, with males battling each other for access to prime habitat and to females. In the field, the hierarchy is more complicated—a lizard defending his own territory is more likely to win a fight, she thinks. She figured the biggest males would also be more likely to triumph, either in the lab or the field, and thus achieve larger territory and more females to court.

In order to correlate body characteristics and behaviors with dominance, Johnson’s group set up a sort of lizard fight club, pitting anoles against each other in one-on-one cage matches, with a single perch to battle over. Winners tended to execute more visual displays, performing push-ups and head-bobs and expanding the showy throat skin known as a dewlap. They also chased and bit the losers, who tended to back away and to hide in a corner.

But larger anoles weren’t always the winners in captivity or in the field. “Body size doesn’t predict who wins these fights at all,” says Johnson. Instead, behaviors made a huge difference—the most aggressive lizards won their matches. A longer head also helped, perhaps because it looked to opponents like a serious biting weapon. In the field, animals with a wider head and powerful jaws occupied larger territories with more females present (Anim Behav, 118:65-74, 2016).

Body size still probably matters, Johnson says. She has not yet tested in field studies whether size might help an A. carolinensis male establish his territory or take over a vacated area. And at least in other anole species, bigger males sire more offspring.

Mahler also got a surprise from the anoles when, in 2010, he received an email from Miguel Landestoy, a Dominican naturalist who claimed he’d seen a new species. Mahler was initially skeptical. “Everybody thinks they’ve got a new species,” he says, yet “the Caribbean anoles are the best known anoles, by a long shot.”

Then Mahler opened Landestoy’s pictures. “Holy crap,” he said. “That doesn’t look like anything we’ve seen on Hispaniola.” The critter was huge, by anole standards—about a foot from nose to tail tip. It had short legs, a short tail, and a mottled greenish-gray pattern that suggested it could easily blend into a mossy or lichen-covered branch. “I bought the first cheap flight I could find,” recalls Mahler.

The other thing that struck Mahler about the new species—which he and his colleagues dubbed A. landestoyi—was that it looked similar to anoles found in Cuba. Their clade is called chamaeleonides for their creeping, chameleon-like movements and camouflage prowess. These particular kinds of anoles, scientists had assumed, were unique to Cuba. But here was another species, making its living in many of the same ways, on Hispaniola (Am Nat, 188:357-64, 2016). “This is an example of what might be a seventh ecomorph. . . . Evolution is more predictable than we have yet given it credit for,” says Johnson, who was not involved in the project.

“It’s amazing, in part, that anything new there could be found after all these years,” adds Losos, a coauthor on the study. “The age of discovery is not yet over.”

Caribbean island launches plan to remove invasive rats and goats

Mongabay: Redonda’s invasive black rats and long-horned goats have transformed the once-forested island into a ‘moonscape’, conservationists say

Shreya Dasgupta for Mongabay, part of the Guardian Environment Network

Monday 1 August 201616.51 BST

The remote Caribbean island of Redonda, part of Antigua and Barbuda, is home to numerous species of plants and animals found nowhere else on earth. It is also home to invasive black rats and non-native goats that are wiping out the island’s native, rare wildlife, conservationists say.

To help the island’s flora and fauna, the Government of Antigua and Barbuda is now initiating a plan to remove all goats and rats from the island. The Redonda Restoration Program program has been formed by the Antigua & Barbuda Government and the Environmental Awareness Group (EAG) in collaboration with organizations like Fauna & Flora International, British Mountaineering Council, Island Conservation and Wildlife Management International Ltd.

“This work will dramatically transform an entire island ecosystem,” Sophia Steele of Fauna & Flora International told Mongabay. “It will save a number of rare endemic species from otherwise almost certain extinction, such as the Critically Endangered Redonda tree lizard, which currently finds itself living on an island almost devoid of trees.”

The island currently has a population of over 5,000 invasive black rats that prey on the island’s native species. The rugged island is also home to around 60 long-horned goats that humans brought to Redonda more than a century ago. The rats and goats are believed to have been introduced into the island by a guano mining community, which was disbanded after World War I.

Read on … 

Vibrantly Colored 'Starburst' Scorpionfish Discovered in the Caribbean

By Stephanie Pappas, Live Science Contributor | July 25, 2016 05:20pm ET

A riotously colorful new species of scorpionfish has been found deep in the Caribbean near Curaçao.

The fish is orange-red, with splashes of yellow and pink decorating its fins and face. Its scientific name is Scorpaenodes barrybrowni, after nature photographer Barry Brown, who works with the Smithsonian Institution mission that discovered the deep-sea-living fish.

S. barrybrowni is a denizen of the rocky seafloor and underwater cliffs, spending its time between about 310 and 525 feet (95 to 160 meters) down. Researchers discovered the new species during the Deep Reef Observation Project (DROP), a Smithsonian Institution mission to explore reefs deeper than scuba divers can go. Researchers used a manned submersible, Curasub, to collect samples of scorpionfish from near the island of Curaçao and discovered that several were of a species never seen before.

"The 50- to 300-meter [160 to 980 feet] tropical ocean zone is poorly studied — too deep for conventional scuba and too shallow to be of much interest to really deep-diving submersibles," Carole Baldwin, the lead scientist at DROP, said in a statement. "The Curasub is providing scientists with the technology needed to remedy this gap in our knowledge of Caribbean reef biodiversity."

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The newly discovered Godzilla goby fish

Date: June 8, 2016

Source: Pensoft Publishers

As part of the Deep Reef Observation Project (DROP), initiated by the Smithsonian Institution, a new goby fish species was discovered in the southern Caribbean. Living at depths greater than conventional SCUBA divers can access, yet too shallow to be of interest for deep-diving submersibles, the fish will now be known under the common name of the Godzilla goby.

Its discoverers Drs Luke Tornabene, Ross Robertson and Carole C. Baldwin, all affiliated with the Smithsonian Institution, have described the species in the open access journal ZooKeys.

Formally called Varicus lacerta, the species name translates to 'lizard' in Latin and refers to the reptilian appearance of the fish. Its prime colors are bright yellow and orange, while the eyes are green.

The new goby also has a disproportionately large head and multiple rows of recurved canine teeth in each jaw. This is also why the research team has chosen the common name of the Godzilla goby.

Apart from its lovely coloration, the new fish stands out with its branched, feather-like pelvic-fin rays and the absence of scales.

The scientists caught the Godzilla goby thanks to the manned submersible Curasub, which had already helped in discovering several species over the course of the project. Last year, Drs Ross Robertson and Carole Baldwin had another new goby published in ZooKeys. That time, they even named it after the submersible. Earlier this year, the DROP team also described nine additional new species, many of which were collected by the Curasub.

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Sierra Leone's stinking seaweed linked to Caribbean invasion

Proliferation of thick brown algae is affecting fishing, tourism and marine life on both sides of the Atlantic, say scientists

Lisa O'Carroll

Saturday 17 October 2015 12.00 BST

The pristine white beaches may not be as famous as those of the Caribbean, but their unspoilt beauty makes them a haven for locals and tourists alike. 

But now the shimmering coastline of Sierra Leone is being destroyed by a mysterious brown seaweed which scientists link to a similar invasion affecting beaches thousands of miles away on the other side of the Atlantic.

In some places the strong-smelling algae is piled up to two feet deep, attracting detritus and causing havoc for fishermen.

Jim Franks, a marine scientist who has been studying the phenomenon, believes it is the sargassum seaweed that normally inhabits the Sargasso sea in the north Atlantic Ocean.

Franks and his fellow researchers say this free-floating algae is now proliferating further south nearer the equator and is being swept onto the beaches on both sides of the Atlantic.

The intensity of it is causing concern; 2015 is one of the worst years we have seenVincent Sweeney, Unep

There have been sporadic shows of the algae in the Caribbean in the past four years, although the 2015 invasion is described by a UN official as the most “intense” yet.

Read on ...

The million year old monkey: New evidence confirms the antiquity of fossil primate

Date: September 4, 2015

Source: University of Melbourne

Summary: An international team of scientists have dated a species of fossil monkey found across the Caribbean to just over one million years old. The lead researcher of this study said that the dating of the limestone surrounding the fossils, said the question of the age of primate fossils from this region has puzzled scientists since the days of Darwin and Wallace.

Read on ...

Scientists discover new species of goby fish

JULY 19, 2015

by Shayne Jacopian

As part of the Smithsonian Institution’s Deep Reef Observation Project (DROP), Doctors Carole Baldwin and Ross Robertson have discovered a new variety of goby fish that is smaller, has unique coloration, and lives at a deeper habitat (70-80m) in the southern Caribbean. This new species was named Coryphopterus curasub, after the Curasub submersible that enabled their deep-reef research.

Here, check out the picture provided by the researchers:

While the marine life of shallow Caribbean coral reefs has been studied for over 150 years, studying environments far deeper wasn’t possible until the advent of manned submersibles that can be taken 300 meters under the sea.

Still, the habitats just below shallow coral reefs goes largely ignored.

"Deep reefs are diverse ecosystems in tropical seas that science has largely missed," said Dr. Baldwin. "Too deep to access using SCUBA gear and too shallow to be of much interest to deep-diving submersibles capable of descending thousands of meters."

"How incomplete is our picture of tropical reef biodiversity if so little attention has been devoted to depths just below those home to shallow coral reefs? We don't know," she said.

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Meets the James Bond rodent

It's the size of a cat and looks like an oversized guinea pig, but the James Bond hutia has managed to avoid detection until now

Presented by

Melissa Hogenboom

A new cat-sized rodent has been discovered on the Caribbean island Hispaniola.

It weighs more than a kilogram, and has soft-brown fur and a short tail. It is also nocturnal and lives in small burrows or caves, which might explain why it has avoided detection for so long.

Its name: Bond, James Bond. Or at least that's the version that rolls off the tongue. Its scientific classification is Plagiodontia aedium bondi.

This may require some explanation.

James Bond was a real-life ornithologist based in the Caribbean. When Ian Fleming created his fictional master of sneak, he took his name from the ornithologist.

Bond discovered that there was a barrier running across Hispaniola, on either side of which the animals are noticeably different.

Centuries ago, there was a shallow sea channel running across the island, which prevented animals from moving freely. The barrier became known as "Bond's line".

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Invasive lionfish may have had multiple points-of-origin in Caribbean

April 24, 2015

Chuck Bednar for redOrbit.com – @BednarChuck

An invasive predatory fish that has been rapidly expanding its presence in the Caribbean Basin and the Western Atlantic originated from multiple locations, not just one as previously believed, according to research published in a recent edition of the journal Marine Biology.

The venomous, coral reef-dwelling red lionfish had long been thought to have been introduced in Florida. In the new study, however, a team of US Geological Survey scientists propose that there were multiple points of origin, including some further south in the Caribbean Basin range.

Two genetically distinct populations discovered

Using new genetic data to help unravel the mystery, the study authors collected lionfish samples from 14 countries and territories in the Greater Caribbean and Western Atlantic. They discovered unique regional patterns that separated the area into distinct northern and southern regions.

The split occurred in the vicinity of the Bahamas, and given the regional genetic differences they found in the course of their investigation, the study authors now believe that there were multiple introductions of the species. One rare genetic strain was detected in only a few southern samples, but was found to be pervasive in the northern ones, the researchers explained.

Read more at

Corals need more parrotfish to survive

A decline in parrotfish and sea urchin numbers is a bigger cause of Caribbean coral loss than global warming, a new report suggests, and by increasing these populations the reefs have a chance of recovery.

The corals have declined by more than 50 per cent since the 1970s and only about one-sixth of their original coral cover remain.

These species are the area’s two main grazers and the loss of them breaks the delicate eco-balance of corals and allows algae, on which they feed, to smother the reefs.

“The rate at which the Caribbean corals have been declining is truly alarming,” says Carl Gustaf Lundin, Director of IUCN’s Global Marine and Polar Programme.

“But this study brings some very encouraging news: the fate of Caribbean corals is not beyond our control and there are some very concrete steps that we can take to help them recover.”

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