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What species is this lizard?

What species is this lizard?


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A small green lizard (20 cm in size). It was found in the direct neighboorhood of a house, in a small village in the Hungarian hills south of the Balaton lake. It was found in the middle of the day.

Our first guess would be Lacerta viridis. Is this correct?


By the picture and the official distribution it looks to be as you said aLacerta viridis.

Some references and distribution here:

In Western Europe we have a brother specieLacerta bilineata.

Example in Geneva:

The distribution maps shows thatLacerta viridisis mainly present in Easter Europe (including Hungary) andLacerta bilineatais present in the Western Europe.

Both species are similar and the male get the throat blue generally during the breeding season.

This site have also a description of the specie.


Hundreds of Australian lizard species, barely known to science, may face extinction

Credit: E Vanderduys, Fourni par l'auteur

Most of the incredible diversity of life on Earth is yet to be discovered and documented. In some groups of organisms—terrestrial arthropods such as spiders and scorpions, marine invertebrates such as sponges and molluscs, and others—scientists have described fewer than 20% of species.

Even our knowledge of more familiar creatures such as fish and reptiles is far from complete. In our new research, we studied 1,034 known species of Australian lizards and snakes and found we know so little about 164 of them that not even the experts know whether they are fully described or not. Of the remaining 870, almost a third probably need some work to be described properly.

Documenting and naming what species are out there—the work of taxonomists—is crucial for conservation, but it can be difficult for researchers to decide where to focus their efforts. Alongside our lizard research, we have developed a new "return on investment" approach to identify priority species for our efforts.

We identified several hotspots across Australia where research is likely to be rewarded. More broadly, our approach can help target taxonomic research for conservation worldwide.

Why we need to look at species more closely

As more and more species are threatened by land clearing, climate change and other human activities, our research highlights that we are losing even more biodiversity than we know.

Return on investment for taxonomic research on lizards and snakes in Australia. Red areas have high numbers of species and high conservation value. Hotspots include the Kimberley in WA, northern tropical savannas and also far north eastern QLD. Credit: R. Tingley, Author provided

Conservation often relies on species-level assessments such as those conducted by the International Union for Conservation of Nature (IUCN) Red List, which lists threatened species. Although new species are being discovered all the time, a key problem is that already named "species" may harbor multiple undocumented and unnamed species. This hidden diversity remains invisible to conservation assessment.

One such example are the Grassland Earless Dragons (Tympanocryptis spp.) found in the temperate native grasslands of south-eastern Australia. These small secretive lizards were grouped within a single species (Tympanocryptis pinguicolla) and listed as Endangered on the IUCN Red List.

But recent taxonomic research split this single species into four, each occurring in an isolated region of grasslands. One of these new species may represent the first extinction of a reptile on mainland Australia and the other three have a high probability of being threatened.

Scientists call documenting and describing species "taxonomy." Our research shows the importance of prioritizing taxonomy in the effort to conserve and protect species.

The Roma Earless Dragon (Tympanocryptis wilsoni), described in 2014, lives only in grasslands in the western Darling Downs QLD and has recently been listed as Vulnerable in Queensland. Credit: A. O'Grady, Author provided

Many government agencies do take some account of groups smaller than species in their conservation efforts, such as distinct populations. But these are often ambiguously defined and lack formal recognition, so they are not widely used. That's where taxonomists come in, to identify species and describe them fully.

Our new research was a collaboration of 30 taxonomists and systematists, who teamed up to find a good way of working out which species should be a priority for taxonomic research for conservation outcomes. This new approach compares the amount of work needed with the likelihood of finding previously unknown species that are at risk of extinction.

The research team, who are experts on the taxonomy and systematics of Australia's reptiles, implemented this new approach on Australian lizards and snakes. This group of reptiles is ideal as a test case because Australia is a global hotspot of lizard diversity—and we also have a strong community of taxonomic experts.

Barrier Range Dragon (Ctenophorus mirrityana), described in 2013, is restricted to rocky ranges in western NSW and is listed as Endangered in NSW. Credit: S. Wilson, Author provided

Australia's lizards and snakes

Of the 1,034 Australian lizard and snake species, we were able to assess whether 870 of them may contain undescribed species. This means we know so little about the remaining 164 species that even the experts could not make an informed opinion on whether they contain hidden diversity. There is so much still to learn!

Of the 870 species experts could assess, they determined 282 probably or definitely needed more taxonomic research. Mapping the distributions of these species indicated hotspot regions for this taxonomic research, including the Kimberley, the Tanami Desert region, western Victoria and offshore islands (such as Tasmania, Lord Howe and Norfolk Islands). Some areas in the Kimberley region had more than 60 species that need further taxonomic research.

We found 17.6% of the 282 species that need more taxonomic research contained undescribed species that would probably be of conservation concern, and 24 had a high probability of being threatened with extinction. Taxonomists know that there are undescribed species because there is some data available already but the description of these species—the process of defining and naming—has not been done.

These high-priority species belong to a range of families including geckos, skinks and dragons found across Australia.

The high number of undescribed species, especially those with significant likelihood of being endangered, was a shock to even the experts. The IUCN currently estimates only 6.3% of Australian lizards and snakes require taxonomic revision, but this is obviously a significant underestimate.

In this map, red hotspot areas have lower species diversity but still a very high average return on investment. National hotspots include Tasmania, western Victoria and the Tanami Desert region in WA and NT. Credit: R. Tingley, Author provided

A race against extinction

Beyond lizards, there is a huge backlog of species awaiting description.

Recent projects have used genetic analyses to discover unknown species, including a $180 million global BIOSCAN effort aiming to identify millions of new species. However, genetics is only a first step in the formal recognition of species.

The taxonomic process of documenting, describing and naming species requires multiple further steps. These steps include a comprehensive diagnostic assessment using a combination of evidence, such as genetics and morphology, to uniquely distinguish each species from another. This process requires a high level of familiarity and scholarship of the group in question.

Among the Australian lizards and snakes alone, there is a backlog of 59 undescribed species for which only the final elements of taxonomic research are awaiting completion.

The Mt Elliot Sunskink (Lampropholis elliotensis), described in 2018, is found in leaf litter of highland rainforest above 600m on Mt Elliot in Bowling Green Bay National Park. Queensland, and is probably Vulnerable. Credit: C. Hoskin, Author provided

To work through these taxonomic backlogs—let alone species that are so far entirely unknown—resources need to be invested in taxonomy, including research funding and increased provision of viable career paths.

Without taxonomic research, the conservation assessment of these undocumented species will not proceed. There are untold numbers of species needing taxonomic research that are already under threat of extinction. If we don't hurry, they may go extinct before we even know they exist.

This article is republished from The Conversation under a Creative Commons license. Read the original article.


24 threatened lizard species discovered

U.S. researchers have identified two dozen new species of lizards on the Caribbean islands, and about half of them may be extinct or close to extinction.

Blair Hedges, a professor of biology at Penn State University, led the study in the New Zealand journal Zootaxa that was published Monday and co-authored by Caitlin Conn, a researcher at the University of Georgia.

Skinks typically have small smooth round scales, thick bodies, strong necks and short legs or snake-like bodies. The team identified 39 types of skink — six of which were already recognized and nine named long ago but considered invalid until now – by examining museum specimens, DNA sequences and the animals themselves.

The discovery of new reptile species is relatively common, with about 130 added to the global species count each year, but the authors note that researchers haven’t identified more than 20 species at a time since the 1800s.

The lizards will, however, join an unappealing club. Of more than 3,000 reptiles listed as endangered by the International Union for Conservation of Nature, the skinks are likely to join the quarter classified as being threatened with extinction.

"The mongoose is the predator we believe is responsible for many of the species' close-to-extinction status in the Caribbean," said Hedges, adding that the mongoose was introduced from India in 1872 to control rats in sugar cane fields.

Mongooses have been spreading across the islands for decades and, Hedges says, have "nearly exterminated this entire reptile fauna, which had gone largely unnoticed by scientists and conservationists until now."

Skinks produce a human-like placenta and gestate offspring for up to a year, which makes them unique among lizards but may also make pregnant females more vulnerable to predators.

New data may guide conservation efforts

Hedges and Conn added that human activity, especially the removal of forests, is also contributing to the decline of many island species.

The new data may help guide conservation efforts, as well as further research on the geographic distribution and adaptation techniques of the lizards.

"We were completely surprised to find what amounts to a new fauna, with co-occurring species and different ecological types," said Hedges.

"Now, one of the smallest groups of lizards in this region of the world has become one of the largest groups."


Effects of Predation on the Niche of Lizards

This activity guides the analysis of a published scientific figure from a study that investigated how a new predator affected the behavior of Bahaman anoles.

Between April 1996 and April 1997, a large lizard called Leiocephalus carinatus colonized a small island in the Bahamas. L. carinatus preys on smaller lizards, including the island’s native anole species Anolis sagrei. Because L. carinatus hunts for prey on the ground, A. sagrei can avoid this predator by perching on the branches of trees or shrubs. The figure shows the average perch height and perch diameter of A. sagrei before and after the colonization of L. carinatus. The “Educator Materials” document includes a captioned figure, background information, graph interpretation, and discussion questions. The “Student Handout” includes a captioned figure and background information.

Student Learning Targets
  • Analyze and interpret data from a scientific figure.
  • Examine the impacts of an introduced or invasive species on other species in an ecosystem.
Details

adaptation, anole, behavioral trait, colonization, introduced species, line graph, predator avoidance

Schoener, Thomas W., David A. Spiller, and Jonathan Losos. “Predation on a common Anolis lizard: can the food-web effects of a devastating predator be reversed?” Ecological Monographs 73, 3 (2002): 383–407. https://doi.org/10.2307/3100096.

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Behavior & lifestyle

Monitor lizards are solitary animals. However, some species of monitor lizards are found in groups of 25 monitors.

The group of monitor lizards maintains a vast territory. They remain active throughout the day in their territory and prey on mammals and other small reptiles.

Monitor lizards lay 7-37 eggs. They cover the eggs with soil or hide the eggs in the hollow of tree stumps.

Let’s know more about the monitor lizard species that are native to Africa. These monitor lizards show some interesting behaviors. You can read about their behavior and lifestyle below.

Nile monitor (Varanus niloticus)

Nile monitors, a large member of the monitor lizard’s family, live in Sub-Saharan Africa and along the Nile. It is also called the African small-grain lizard and iguana.

Nile monitors are carnivores. These monitors are well-adapted for an aquatic lifestyle. They can climb trees and quickly run on land.

West African Nile monitor (Varnus stellatus)

West African Nile monitors are native to West African forests and nearby areas of the savannah region. Recently these monitors have been introduced to South Florida, United States as an invasive species.

Previously ornate monitors were included in the Nile monitor species. However, the Nile monitors and West African Nile monitors show similar behavior and lifestyle.

Ornate monitor (Varanus ornatus)

Ornate monitors live in West and Middle Africa. This monitor is large and they can grow close to 2 meters in length.

It was also considered as one of the subspecies of the Nile monitor until 1997. The recent studies have cleared all the doubts about this “species complex”. Ornate monitors are mostly found in the canopy forests.


A team of evolutionary biologists from the University of Toronto has shown that Anolis lizards, or anoles, are able to breathe underwater with the aid of a bubble clinging to their snouts.

Anoles are a diverse group of lizards found throughout the tropical Americas. Some anoles are stream specialists, and these semi-aquatic species frequently dive underwater to avoid predators, where they can remain submerged for as long as 18 minutes.

“We found that semi-aquatic anoles exhale air into a bubble that clings to their skin,” says Chris Boccia, a recent master of science graduate from the Faculty of Arts & Science’s Department of Ecology & Evolutionary Biology (EEB). Boccia is lead author of a paper describing the finding being published May 12 in Current Biology.

“The lizards then re-inhale the air,” says Boccia, “a maneuver we’ve termed ‘rebreathing’ after the scuba-diving technology.”

The researchers measured the oxygen (O2) content of the air in the bubbles and found that it decreased over time, confirming that rebreathed air is involved in respiration.

Chris Boccia is a recent master of science graduate from the Faculty of Arts & Science’s Department of Ecology & Evolutionary Biology. Photo courtesy of Chris Boccia.

Rebreathing likely evolved because the ability to stay submerged longer increases the lizard’s chances of eluding predators.

The authors studied six species of semi-aquatic anoles and found that all possessed the rebreathing trait, despite most species being distantly related. While rebreathing has been studied extensively in aquatic arthropods like water beetles, it was not expected in lizards because of physiological differences between arthropods and vertebrates.

“Rebreathing had never been considered as a potential natural mechanism for underwater respiration in vertebrates,” says Luke Mahler, an assistant professor in EEB and Boccia’s thesis supervisor. “But our work shows that this is possible and that anoles have deployed this strategy repeatedly in species that use aquatic habitats.”

Luke Mahler is an assistant professor in the Department of Ecology & Evolutionary Biology.

Mahler and co-author Richard Glor, from the University of Kansas, first observed anoles rebreathing in Haiti in 2009 but were unable to carry out further observations or experiments. Another co-author, Lindsey Swierk, from Binghamton University, State University of New York, described the same behaviour in a Costa Rican species in 2019. These early observations suggested that rebreathing was an adaptation for diving, but this idea had not been tested until now.

Boccia became interested in aquatic anoles after encountering one in Panama. He began his rebreathing investigations in Costa Rica in 2017 and continued the research in Colombia and Mexico.

As the authors point out, the rebreathing trait may have developed because anoles’ skin is hydrophobic — it repels water — a characteristic that likely evolved in anoles because it protects them from rain and parasites. Underwater, air bubbles cling to hydrophobic skin and the ability to exploit these bubbles for breathing developed as a result.

While further work is required to understand how the process works in detail, Boccia, Mahler and their co-authors suggest different ways in which rebreathing may function.

In its simplest form, the air bubble on a lizard’s snout likely acts like a scuba tank, providing a submerged animal with a supply of air in addition to the air in its lungs. This is what aquatic arthropods like water beetles do to extend the time they can remain submerged.

A submerged Anolis lizard with a rebreathing bubble on its snout. Photo: Lindsey Swierk.

The researchers also suggest that the rebreathing process may facilitate using air found in a lizard’s nasal passages, mouth and windpipe that would otherwise not be used by the lizard in breathing.

The bubble may also help rid waste carbon dioxide (CO2) from exhaled air through a process other researchers have already observed in aquatic arthropods. Those studies concluded that because CO2 is highly soluble in water and because the level of CO2 in the bubbles is higher than in the surrounding water, exhaled CO2 dissolves into the surrounding water rather than being rebreathed.

Finally, the authors speculate that the bubble may act as a gill and absorb oxygen from the water — again, something already observed in arthropods. Boccia and Mahler are planning further research to confirm if these rebreathing processes are occurring with anoles.

According to Mahler, “This work enriches our understanding of the creative and unexpected ways that organisms meet the challenges posed by their environments. That is valuable in its own right, but discoveries like this can also be valuable to humans as we seek solutions to our own challenging problems.”

“It’s too early to tell if lizard rebreathing will lead to any particular human innovations,” says Boccia, “But biomimicry of rebreathing may be an interesting proposition for several fields — including scuba-diving rebreathing technology, which motivated our naming of this phenomenon.”

Mahler’s participation in the research was supported by an NSERC Discovery Grant and a Harvard University Ken Miyata Field Research Award. Boccia’s participation was supported by an NSERC CGS M Grant, a National Geographic Young Explorer Grant and a Sigma Xi Grant in Aid of Research.


What species is this lizard? - Biology

ANI
15 Jun 2021, 03:18 GMT+10

Washington [US], June 14 (ANI): During a recent study, an international research team described a new species of Oculudentavis and provided further evidence that the animal first identified as a hummingbird-sized dinosaur was actually a lizard.

The researchers published their findings in Current Biology. This new species, named Oculudentavis naga in honour of the Naga people of Myanmar and India, is represented by a partial skeleton that includes a complete skull, exquisitely preserved in amber with visible scales and soft tissue.

The specimen is in the same genus as Oculudentavis khaungraae, whose original description as the smallest known bird was retracted last year. The two fossils were found in the same area and are about 99 million years old.

The team, led by Arnau Bolet of Barcelona's Institut Catala de Paleontologia Miquel Crusafont, used CT scans to separate, analyze and compare each bone in the two species digitally, uncovering a number of physical characteristics that earmark the small animals like lizards. Oculudentavis is so strange, however, it was difficult to categorize without close examination of its features, Bolet said.

"The specimen puzzled all of us at first because if it was a lizard, it was a highly unusual one," he said in an institutional press release.

Bolet and fellow lizard experts from around the world first noted the specimen while studying a collection of amber fossils acquired from Myanmar by gemologist Adolf Peretti. (Note: The mining and sale of Burmese amber are often entangled with human rights abuses. Peretti purchased the fossil legally prior to the conflict in 2017. More details appear in an ethics statement at the end of this story).

Herpetologist Juan Diego Daza examined the small, unusual skull, preserved with a short portion of the spine and shoulder bones. He, too, was confused by its odd array of features: Could it be some kind of pterodactyl or possibly an ancient relative of monitor lizards?"From the moment we uploaded the first CT scan, everyone was brainstorming what it could be," said Daza, assistant professor of biological sciences at Sam Houston State University. "In the end, a closer look and our analyses help us clarify its position."Major clues that the mystery animal was a lizard included the presence of scales teeth attached directly to its jawbone, rather than nestled in sockets, as dinosaur teeth were lizard-like eye structures and shoulder bones and a hockey stick-shaped skull bone that is universally shared among scaled reptiles, also known as squamates.

The team also determined both species' skulls had deformed during preservation. Oculudentavis khaungraae's snout was squeezed into a narrower, more beaklike profile while O. naga's braincase - the part of the skull that encloses the brain - was compressed. The distortions highlighted birdlike features in one skull and lizard-like features in the other, said study co-author Edward Stanley, director of the Florida Museum of Natural History's Digital Discovery and Dissemination Laboratory.

"Imagine taking a lizard and pinching its nose into a triangular shape," Stanley said. "It would look a lot more like a bird."Oculudentavis' birdlike skull proportions, however, do not indicate that it was related to birds, said study co-author Susan Evans, professor of vertebrate morphology and paleontology at University College London.

"Despite presenting a vaulted cranium and a long and tapering snout, it does not present meaningful physical characters that can be used to sustain a close relationship to birds, and all of its features indicate that it is a lizard," she said.

While the two species' skulls do not closely resemble one another at first glance, their shared characteristics became clearer as the researchers digitally isolated each bone and compared them with each other.

The differences were minimized when the original shape of both fossils was reconstructed through a painstaking process known as retrodeformation, conducted by Marta Vidal-Garcia from the University of Calgary in Canada.

"We concluded that both specimens are similar enough to belong to the same genus, Oculudentavis, but a number of differences suggest that they represent separate species," Bolet said.

In the better-preserved O. naga specimen, the team was also able to identify a raised crest running down the top of the snout and a flap of loose skin under the chin that may have been inflated in the display, Evans said. However, the researchers came up short in their attempts to find Oculudentavis' exact position in the lizard family tree.

"It's a really weird animal. It's unlike any other lizard we have today," Daza said. "We think it represents a group of squamates we were not aware of."The Cretaceous Period, 145.5 to 66 million years ago, gave rise to many lizard and snake groups on the planet today, but tracing fossils from this era to their closest living relatives can be difficult, Daza said.

"We estimate that many lizards originated during this time, but they still hadn't evolved their modern appearance," he said. "That's why they can trick us. They may have characteristics of this group or that one, but in reality, they don't match perfectly."The majority of the study was conducted with CT data created at the Australian Centre for Neutron Scattering and the High-Resolution X-ray Computed Tomography Facility at the University of Texas at Austin. O. naga is now available digitally to anyone with Internet access, which allows the team's findings to be reassessed and opens up the possibility of new discoveries, Stanley said.

"With paleontology, you often have one specimen of a species to work with, which makes that individual very important. Researchers can therefore be quite protective of it, but our mindset is 'Let's put it out there,'" Stanley said. "The important thing is that the research gets done, not necessarily that we do the research. We feel that's the way it should be."While Myanmar's amber deposits are a treasure trove of fossil lizards found nowhere else in the world, Daza said the consensus among paleontologists is that acquiring Burmese amber ethically has become increasingly difficult, especially after the military seized control in February.

"As scientists, we feel it is our job to unveil these priceless traces of life, so the whole world can know more about the past. But we have to be extremely careful that during the process, we don't benefit a group of people committing crimes against humanity," he said. "In the end, the credit should go to the miners who risk their lives to recover these amazing amber fossils."Other study co-authors are J. Salvador Arias of Argentina's National Scientific and Technical Research Council (CONICET - Miguel Lillo Foundation) Andrej Cernansky of Comenius University in Bratislava, Slovakia Aaron Bauer of Villanova University Joseph Bevitt of the Australian Nuclear Science and Technology Organisation and Adolf Peretti of the Peretti Museum Foundation in Switzerland.

A 3D digitized specimen of O. naga is available online via MorphoSource. The O. naga fossil is housed at the Peretti Museum Foundation in Switzerland, and the O. khaungraae specimen is at the Hupoge Amber Museum in China.

The specimen was acquired following the ethical guidelines for the use of Burmese amber set forth by the Society for Vertebrate Paleontology. The specimen was purchased from authorized companies that are independent of military groups.

These companies export amber pieces legally from Myanmar, following an ethical code that ensures no violations of human rights were committed during mining and commercialization and that money derived from sales did not support armed conflict. The fossil has an authenticated paper trail, including export permits from Myanmar. All documentation is available from the Peretti Museum Foundation upon request. (ANI)


How an Asexual Lizard Procreates Alone

All moms and no dads, the whiptail still comes up with genetically diverse offspring.

N. Mexico Whiptail Lizard

Without females, lizards in the Aspidoscelis genus, like this New Mexico Whiptail (Aspidoscelis neomexicana), reproduce asexually. Unlike other animals that produce this way, however, their DNA changes from generation to generation.

Photograph by Bill Gorum/Alamy Stock Photo

In sexual reproduction&mdashthe way most life-forms procreate&mdasheach parent provides half an offspring's chromosomes. Over generations, this mating and procreating shuffles the DNA deck, giving sexual reproducers a genetic diversity that helps them adapt to changing environments.

By contrast, asexual reproducers&mdashsome 70 vertebrate species and many less-complex organisms&mdash"use all the chromosomes they have" to solitarily produce offspring that are genetic clones, molecular biologist Peter Baumann says. Because the organisms are genetically identical, they're more vulnerable: A disease or an environmental shift that kills one could kill all.

But there's a twist in the case of the genus Aspidoscelis, the asexually reproducing whiptail lizards that Baumann and his colleagues have been studying at the United States' Stowers Institute for Medical Research in Kansas City, Missouri. The lizards are all female and parthenogenetic, meaning their eggs develop into embryos without fertilization.

But before the eggs form, Baumann's team discovered, the females' cells gain twice the usual number of chromosomes during meiosis. This results in a standard pair of chromosones derived from two sets of pairs. So the eggs get a full chromosome count and genetic variety and breadth (known as heterozygosity) rivaling that of a sexually reproducing lizard.

Why does this occur? Because long ago, Baumann says, lizards of the genus Aspidoscelis had "a hybridization event"&mdashthat is, females of one species broke form and mated with males of another species. Those outlier liaisons gave whiptails robust heterozygosity, which has been preserved by the identical replication&mdashessentially, cloning&mdashthat occurs in asexual reproduction. It's a genetic-diversity advantage that today's females still enjoy and propagate.

Without females, lizards in the Aspidoscelis genus, like this New Mexico Whiptail (Aspidoscelis neomexicana), reproduce asexually. Unlike other animals that produce this way, however, their DNA changes from generation to generation.


Defining ‘species’ is a fuzzy art

SPECIES SCHMECIES This swarm of diversely patterned Heliconius butterflies is actually just two species known for mimicry. How to define a species turns out to have more pitfalls than these butterflies have spots.

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November 1, 2017 at 9:00 am

The funniest thing I’ve ever said to any botanist was, “What is a species?” Well, it certainly got the most spontaneous laugh. I don’t think Barbara Ertter, who doesn’t remember the long-ago moment, was being mean. Her laugh was more of a “where do I even start” response to an almost impossible question.

At first glance, “species” is a basic vocabulary word schoolchildren can ace on a test by reciting something close to: a group of living things that create fertile offspring when mating with each other but not when mating with outsiders. Ask scientists who devote careers to designating those species, however, and there’s no typical answer. Scientists do not agree.

“You may be stirring up a hornet’s nest,” warns evolutionary zoologist Frank E. Zachos of Austria’s Natural History Museum Vienna when I ask my “what is a species” question. “People sometimes react very emotionally when it comes to species concepts.” He should know, having cataloged 32 of them in his 2016 overview, Species Concepts in Biology.

The widespread schoolroom definition above, known as the biological species concept, is No. 2 in his catalog, which he tactfully arranges in alphabetical order. This single concept has been so pervasive that whenever Science News publishes something about species interbreeding, readers want to know if we have lost our grip on logic. Separate species, by definition, can do no such thing.

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As concerned readers question our reports of hybrid species, a vast debate among specialists over how to define and identify species rolls on. The biological species concept has drawbacks, to put it gently, for coping with much of the variety and oddness of life. Alternative concepts have pros and cons, too. As specialists argue over the fine details of species concepts, I’m struck by how often the word “fuzzy” comes up.

Also striking is how at least some of the people who actually appraise species for a living have made peace with the perpetual tumult over defining just what it is they get up in the morning to study. The ambiguities seemed less jarring to me after a September conversation with the Smithsonian’s Kevin de Queiroz, deep in the maze of doors and corridors behind the scenes at the National Museum of Natural History in Washington, D.C. As a systematic biologist, he studies the evolutionary histories of reptiles, and designates species, which explains a door we passed marked “Alcohol Room.” Fire regulations require special handling for jars of animal specimens preserved in alcohol. In the cacophony of species concepts, de Queiroz sees some commonality.

Ertter, affiliated with the University of California, Berkeley and the College of Idaho in Caldwell, embraces the ambiguity. “Why do we expect that nature is nice and neat and clean? Because it’s more convenient for us,” she says. “It’s up to us to figure it out, not to demand that it’s one way or another.”

Story continues below images

Hybridizing Potentilla flowers, group-reproducing slime molds (wolf’s milk, shown) and all-female New Mexico whiptail lizards breed in ways that poke holes in the familiar biological species concept. Clockwise from top: Gary A. Monroe/USDA-NRCS PLANTS Database Alexander62/iStockphoto Roger Shaw/Flickr.com (CC BY-NC-SA 2.0)

Problems with the old standard

The biological species concept has an intuitive appeal. Elephants don’t mate with oak trees to produce really big acorns. Horses can mate with donkeys, but the resulting mules are infertile. The most famous form of this species definition may be from evolutionary biologist Ernst Mayr, who wrote in 1942: “Species are groups of actually or potentially interbreeding natural populations, which are reproductively isolated from other such groups.” Famous, yes, but limited.

Modern genetics has revealed that much of the diversity of life on Earth is found in single-celled organisms that reproduce asexually by splitting in two — thus flummoxing the definition. Of course the single-celled hordes still form … somethings. There isn’t just one vast smear of microbial life where all shapes, sizes, body features and chemistry can be found in any old mix. There are clusters with shared traits, some of which cause human and agricultural diseases and some of which photosynthesize in the ocean, producing as much as 70 percent of the oxygen that we and other living things breathe. Humans need to understand the history of microbes and have names to talk about these influential organisms.

Rather than deciding that these microbes are just not species, which is one popular view, microbiome researcher Seth Bordenstein suggests “just twisting the biological species concept ever so slightly.” Genes don’t shuffle around via sex, but there’s still kidnapping of genes from other asexuals. This process might count as something like interbreeding, says Bordenstein, of Vanderbilt University in Nashville. With that interpretation, the biological species concept “could apply to microbes.” Sort of.

But one-celled microbes aren’t the only asexuals. Even vertebrates have their no-sex scandals. New Mexico whiptail lizards are a species: Aspidoscelis neomexicanus. Yet females lay eggs with no male fertilization males don’t exist.

And plant reproduction, oy. The blends of sex and no-sex don’t fit into a tidy biological species concept. Consider a new variety of a western North American species that Ertter and botanist Alexa DiNicola of the University of Wisconsin–Madison named this year. Potentilla versicolor var. darrachii belongs to a genus that’s closely related to strawberries. Plants in the genus open little five-petaled flowers and readily form classic seeds that mix genes from pollen and ovule. On occasion, though, the genes in the seed’s embryo are only mom’s. “They basically use seeds as a form of cloning,” Ertter says. The male pollen in these cases merely jump-starts formation of the seed’s food supply.

That’s just one reason Potentilla is “one of the messiest genera you can imagine,” Ertter says. She and DiNicola hauled collectors’ gear on a backpacking trip in Oregon to sample some of the plants. The team found signs that one species was hybridizing readily with another the species were so different that even a nonbotanist could tell them apart (leaves shaped like a feather versus an open fan). Sharing genes across species is evidently common in this genus and not at all rare among plants.

Such shenanigans have led Ertter to what she calls the “fuzzy species concept.” After looking at all the kinds of evidence she might muster for a plant, from its genes and distribution to the details of petals, leaf hairs and other parts, she sides with the preponderance of data to designate a species.

Concept zoo

There can be a lot of messiness in picking out the limits of species, but that’s OK with philosopher Matt Haber of the University of Utah in Salt Lake City. He organized three conferences this year on the complications of determining what’s a species when fire hoses of genetic information spew signs of unexpected gene mixing and tell different stories depending on the genes tracked.

“Just because boundaries are fuzzy,” Haber says, “doesn’t mean they aren’t actually boundaries.” We may not be used to thinking about species distinctions this way, but other familiar distinctions have similar “gradient boundaries,” as he calls them. “Cold and hot weather,” he says. We recognize winter weather as different from summer even though fall and spring have neither a sharp switch point nor a smooth slide. Species, too, could have zones of erratic mixing but still overall be defined as species.

There are a whole lot of species concepts, says Richard Richards, a philosopher of biology at the University of Alabama in Tuscaloosa. “We use different rules for different kinds of organisms,” he says. “For vertebrates, the interbreeding rule is useful. Not so for the many kinds of nonsexually reproducing organisms out there.”

What’s called the agamospecies concept applies to asexual organisms and cobbles together genetic or other observable similarities. The ecological species concept emphasizes adaptations to particular environmental zones. The nothospecies concept applies to plants arising when parent species hybridize. And so on. That’s not even counting “the cynical species concept,” which Zachos has heard defining a species as “whatever a taxonomist says it is.”

Land and money

Species definitions can have ramifications, financial and otherwise, for the wider world. Choosing one species concept over another can change how a creature gets classified, which could determine whether conservation laws protect it. The coastal California gnatcatcher’s status as a distinct subspecies makes it eligible for federal protection to keep the bird’s shrub-land as habitat rather than a real estate development. Critics have argued, however, that the bird isn’t distinct enough from its relatives to merit special protection.

Mammal specialists are switching over to what’s called a phylogenetic concept, Zachos says. The phylogenetic concept allows populations to upgrade to full species status if they share an ancestor and have some unique trait, such as a particular gene. Among the complex consequences of following this concept is possible “taxonomic inflation,” he warns. A 2011 rethink of the ungulate group of sheep, goats, antelope and more ballooned the species count from 143 to 279, for instance. In biology as in economics, “inflation causes devaluation,” Zachos says. “People get bored. If one of the tiger species goes extinct, they say, ‘So what? There are five more.’ ”

As individual taxonomists choose their pet concepts, “ ‘species’ are often created or dismissed arbitrarily,” argued two researchers from Australia in the June 1 Nature. The duo warned of potential “anarchy” and went as far as calling for an international organization to reduce the chaos.

“A long list of silly examples of complications caused by poor taxonomic governance” pushed conservation biologist Stephen Garnett of Charles Darwin University in Darwin to cowrite the piece. Standardizing species concepts across broad groups, mammals and reptiles, for instance, would reduce the chaos, says coauthor Leslie Christidis, a taxonomist at Southern Cross University in Coffs Harbour. The notion of standard-setting in determining species has stirred a bit of agreement and a lot of dissent. “We united the taxonomic community — unfortunately against us,” he says.

The furor illustrates the diversity of ways that people are sorting out what a species is among life’s various organisms. Historian and philosopher of biology John S. Wilkins of the University of Melbourne in Australia was almost kidding when he wrote that there are “n+1 definitions of ‘species’ in a room of n biologists.”

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A rough idea

Extremely squeezed-down summaries of just a few of the dozens of species concepts give a rough sense of the differing approaches researchers use to define a species. The full statements for each concept are far more intricate.

The commons

Thinking about the seemingly intractable ambiguities of the species concepts got a lot easier for me after my visit with de Queiroz. His office was the opposite of the Hollywood biologist’s jumble of dessicated specimens, dangling skeletons and tottering towers of books. The long room was mostly filled with rows of librarian-tidy metal bookcases hiding a desk cave at the far end. When I asked him what a species is, he didn’t laugh. He explained that there’s more agreement than the swarm of species concepts might suggest.

The concepts have in common their references to organisms in a population lineage, or line of descent. As evolutionary time passes, a lineage moves away and its various connected populations grow separate from others of the same ancestry. The concepts share the basic idea that a species is a “separately evolving metapopulation lineage,” he says.

To identify those lineages in practice, however, requires finding evidence of interbreeding or patterns of shared traits. Adding such criteria to the concepts is what creates the crazy diversity. Defining the term species is “not the problem,” he says. “The problem is in identifying a species.”

He calls up a map on his computer from a recent paper a former lab member published on fringe-toed lizards. Colored blobs float over dark lines of a map of the western United States. Three blobs are clearly designated species based on multiple lines of evidence. Three lizard patches, however, are perplexing. Various ways of testing these lizard populations lead to contradictory results.

No matter how badly we want the process of applying a species definition to be clear-cut for all creatures in all cases, “it just isn’t,” de Queiroz says. And that’s exactly what evolutionary biology predicts. Evolution is an ongoing process, with lineages splitting or rejoining at their own pace. Exploring a living, ever-evolving world of life means finding and accepting fuzziness.

This article appears in the November 11, 2017 issue of Science News with the headline, “The fuzzy art of defining species: A vital concept sparks many arguments.”

Editor’s note: This story was updated on November 7, 2017 to correct the credit for the whiptail lizard image.

Questions or comments on this article? E-mail us at [email protected]

A version of this article appears in the November 11, 2017 issue of Science News.

Citations

S.T. Garnett and L. Christidis. Taxonomy anarchy hampers conservation. Nature. Published online June 1, 2017. doi: 10.1038/546025a.

About Susan Milius

Susan Milius is the life sciences writer, covering organismal biology and evolution, and has a special passion for plants, fungi and invertebrates. She studied biology and English literature.


A biologist studying a desert ecosystem observes that the population of a lizard species increases following a particularly hot, dry period that causes a snake species to decline. what could the biologists hypothesize about the roles of theses two species? a: the lizard preys on the snake b: the lizard is a parasite of the snake c: the snake and the lizard use the same limiting recourse d: the snake is a keystone species in the ecosystem me its for a huge test and i need the answer!

Based on the description of events, being that the lizard population appears to increase as soon as the snake population decreases, it appears that the snakes prey on the lizards. This suggests that the snake is a keystone species. A keystone species is one that has a dramatic effect on maintaining the balance of an ecosystem. As soon as the snake population decreases, major changes occur to the ecosystem, such as the lizard population increasing.

Therefore, the answer is D: The snake is a keystone species in the ecosystem.



Comments:

  1. Pete

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  2. Lynne

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