Monday, September 25, 2017

Caribbean Ameivas moved to the genus Pholidoscelis



The family Teiidae is a New World clade of small to large-sized lizards that tend to be active foragers, diurnal, and omnivorous. Whiptails (genus Aspidocelis)in the USA, Racerunners (genus Cnemidophorus) in the Neotropics, the giant Tegus (Tupinmabis and Salvator) in the Neotropics are a few of the major clades. The Ameiva's are primarily Neotropical but also are well represented in the West Indies. In a new paper Tucker et al. (2017) examine the phylogenetic relationships and biogeographic history of Caribbean island ameivas and place them in the genus Pholidoscelis. The authors use phylogenomic and mitochondrial DNA datasets to reconstruct a well-supported phylogeny and assess historical colonization patterns in the group. They obtained sequence data from 316 nuclear loci and one mitochondrial marker for 16 of the 19 extant species of the Caribbean endemic genus Pholidoscelis. To estimate divergence times, they used fossil teiids to calibrate a timetree which was used to elucidate the historical biogeography of these lizards. All phylogenetic analyses recovered four well-supported species groups (clades) recognized previously and supported novel relationships of those groups, including a (P. auberi + P. lineolatus) clade (western + central Caribbean), and a (P. exsul + P. plei) clade (eastern Caribbean). Divergence between Pholidoscelis and its sister clade was estimated to have occurred ~25 Ma, with subsequent diversification on Caribbean islands occurring over the last 11 Myr. Of the six models compared in the biogeographic analyses, the scenario which considered the distance among islands and allowed dispersal in all directions best fit the data. These reconstructions suggest that the ancestor of this group colonized either Hispaniola or Puerto Rico from Middle America. The authors provide a well-supported phylogeny of Pholidoscelis with novel relationships not reported in previous studies that were based on significantly smaller datasets. They propose that Pholidoscelis colonized the eastern Greater Antilles from Middle America based on our biogeographic analysis, phylogeny, and divergence time estimates. The closing of the Central American Seaway and subsequent formation of the modern Atlantic meridional overturning circulation may have promoted dispersal in this group.

Citation
Tucker DB, Hedges SB, Colli GR, Pyron RA, Sites JW. Genomic timetree and historical biogeography of Caribbean island ameiva lizards (Pholidoscelis: Teiidae). Ecology and Evolution. 2017 Aug.

A frog that cannot hear its own call


Pumpkin toadlets, found in the leaf litter of Brazil's Atlantic forest, are among the smallest frogs in the world.

An international team from Brazil, Denmark, and the United Kingdom, has discovered that two species of these tiny orange frogs cannot hear the sound of their own calls.

This is a unique case in the animal kingdom of a communication signal persisting even after the target audience has lost the ability to detect it.

"We have never seen this before: These frogs make sounds that they cannot hear themselves," says Associate Professor, Jakob Christensen-Dalsgaard, University of Southern Denmark.

He led the laboratory testing of the frogs' hearing abilities at the University of Southern Denmark. The findings have been confirmed by anatomical studies at Cambridge University, UK, showing that the part of the ear responsible for high-frequency hearing is vestigial in these species.

Lead author of the study is Dr. Sandra Goutte, who was postdoc at Universidade Estadual de Campinas, São Paulo, Brazil, when the study was conducted.

Most male frogs call to signal their presence to the opposite sex and find a mate, but this is costly: it could attract predators and parasites, and it uses up energy and time.

"One would think that if a signal is not perceived by its target audience, it would be lost through evolution," says Dr. Sandra Goutte.

Because these tiny frogs are brightly colored, diurnal and known to use visual signals, the researchers hypothesize that visual communication has replaced acoustic communication.

The movement of the throat when males are calling could constitute a visual signal, in which case the call itself would represent a by-product of the true signaling behavior.

Like many brightly-colored tropical frogs, pumpkin toadlets are highly toxic, which may lower the risk of predation when they are calling.

The singular communication system in these pumpkin toadlets is the first example of vestigial sound communication, says Jakob Christensen-Dalsgaard.

Studying the toadlets further will advance our understanding of the mechanisms underlying the evolution of communication systems in animals.

Citation
 Goutte S, Mason MJ, Christensen-Dalsgaard J, Fernando Montealegre-Z F. Chivers BD, Sarria-S FA,  Antoniazzi MM,  Jared C,  Sato LA,  Toledo LF. 2017. Evidence of auditory insensitivity to vocalization frequencies in two frogs. Scientific Reports, 2017; 7 (1) DOI: 10.1038/s41598-017-12145-5

Sunday, May 28, 2017

A new, morphologically cryptic, leaf-nesting frog of the genus Phyllomedusa


Male holotype of Phyllomedusa chaparroi sp. nov. (MUBI 13986) 
Casttoviejo-Fischer and colleagues describe and name the new leaf-nesting frog, Phyllomedusa chaparroi, a medium-sized species (67.9–77.5 mm) from the Amazonian rainforests of northern Peru. Morphologically the new species is most similar to P. boliviana and P. camba, it is indistinguishable from the latter in external qualitative and quantitative traits). However, phylogenetic analysis of combined mitochondrial and nuclear markers place the new species sister to a clade containing P. neildi, P. tarsius, and P. trinitatis. Phyllomedusa chaparroi can be readily differentiated from these species by having a dark reddish-brown iris with indistinct tiny orange spots versus an orange iris with marked dark reticulation found in P. neildi, P. tarsius, and P. trinitatis. Furthermore, the genetic distances for a 532 bp sequence of the 16S gene between the new species and its sister species are 2.8–4.1%, whereas distances are 4.5–5.5% to the morphologically cryptic P. camba. The type series of Phyllomedusa chaparroi includes specimens from two sites, this species seems to occur at various localities in the area of Tarapoto in the Peruvian Amazon. Nonetheless, it seems that this species has been confused with Phyllomedusa camba and the distributional range of both species needs to be thoroughly evaluated, especially at the northern western limits of the known distribution of P. camba.

Citation
Castroviejo-Fisher SA, Köhler J, De La Riva IG, Padial JM.. A new morphologically cryptic species of Phyllomedusa (Anura: Phyllomedusidae) from Amazonian forests of northern Peru revealed by DNA sequences. Zootaxa. 2017 May 22;4269(2):245-64.


Saturday, May 27, 2017

Brazilian microteiids - and the increase of Brazilian lizard species since 1995

Gymnophthalmus underwoodi, a widespread all-female species.
In a new paper, Ribeiro-Junior and Amaral present distribution data of all Alopoglossidae and Gymnophthalmidae lizards known from the Brazilian Amazonia. The paper presents a total of 54 species-level taxa, belonging to 17 genera and two families. This represents 22 more species-level taxa than previously reported. The results  were based on the examination of 17,431 specimens deposited in three North American and eight Brazilian museums, including the main collections harboring Amazonian material. Most species (~80%) are endemic to Amazonia; non-endemic species are mainly associated with open vegetation (savanna) enclaves or open dry (semi-deciduous) forest in Amazonia, with a few exceptions. As a whole, seven taxa (including one species complex) are widespread in Amazonia, six are restricted to eastern Amazonia, seven to western Amazonia, two to southwestern Amazonia, 11 to southern Amazonia, 11 to northern Amazonia (either in part of it or widespread in the Guiana region), and six to the southern peripheral portion of Amazonia. Besides, four species present unique distributions. Considering this study and the other three catalogues of distribution of lizards already published, the total number of lizard species from Brazilian Amazonia increased from 97 to 142 species-level taxa. This represents an increase of 45 species from the region since the last revision in 1995.

Citation
Ribeiro-Junior MA, Amaral S. 2017. Catalogue of distribution of lizards (Reptilia: Squamata) from the Brazilian Amazonia. III. Anguidae, Scincidae, Teiidae. Zootaxa. 2016 Dec 9;4205(5):401-30.

Do not publish


David Lindenmayer, Ben Scheele
Science  26 May 2017:Vol. 356, Issue 6340, pp. 800-801DOI: 10.1126/science.aan1362

Biologists have long valued publishing detailed information on rare and endangered species. Until relatively recently, much of this information was accessible only through accessing specialized scientific journals in university libraries. However, much of these data have been transferred online with the advent of digital platforms and a rapid push to open-access publication. Information is increasingly also available online in public reports and wildlife atlases, and research published behind paywalls can often be found in the public domain. Increased data and information accessibility has many benefits, such as helping to improve repeatability in scientific studies and enhancing collaboration (1, 2). However, such readily accessible information also creates major problems in the context of conserving endangered species.

Increasingly, the dual-use research dilemma (3), in which research can have both substantial positive but also negative impacts, is pervading research on rare and endangered species, with information intended to aid conservation fueling illegal actions that harm biodiversity. Biologists must urgently unlearn parts of their centuries-old publishing culture and rethink the benefits of publishing location data and habitat descriptions for rare and endangered species to avoid unwittingly contributing to further species declines. Restricting information entails some costs, but these must be weighed against the increasing harm of unrestricted information accessibility.

At least three key issues associated with unrestricted access to information on rare and endangered species warrant careful attention. These risks are not new but are greatly exacerbated in an era of digital proliferation and open access. First, unrestricted access to species location information is facilitating a surge in wildlife poaching (4, 5), with many species at risk (6). Poaching has been documented in species within months of their taxonomic description in journals (4). For example, more than 20 newly described reptile species have been targeted in this way, potentially leading to extinction in the wild. Indeed, when the names of some of these species—such as the Chinese cave gecko, Goniurosaurus luii (see the photo)—are typed into a search engine, the text autopopulates to suggest a search to purchase these animals.

Second, unrestricted access to location data and habitat descriptions can disrupt the often delicate relationships between scientists and landowners. We have personal experience of this. Our research in Australia on restoring farmland biodiversity requires repeated access to farms and depends on high levels of trust among landholders. We have detected populations of endangered species such as the pink-tailed worm-lizard (Aprasia parapulchella). Our research permits demand that location records be uploaded to open-access government wildlife atlases. Soon after uploading records, people seeking the rare worm-lizard were caught trespassing, upsetting farmers, damaging important rocky outcrop habitats, and jeopardizing scientist-farmer relationships that have taken years to establish.

Third, unrestricted access to species information has the potential to accelerate habitat destruction and create other negative disturbances. The digital age has brought a desire among many nature enthusiasts to observe, photograph, and sometimes remove animals and plants (7). Animal behavior and habitats are often heavily disturbed in the process (8).

Decisions to publish sensitive information on endangered and newly described rare species must be based around a careful assessment of whether its publication will benefit or harm the target species (see the figure). Key trade-offs must be weighed. For example, easily accessible data can help amass the evidence to challenge development proposals that may affect endangered species. Increased data accessibility can also foster improved scientific repeatability and greater collaboration. Although withholding information may have some negative consequences, this action is increasingly needed (9), given that calls for better regulation and law enforcement to protect atrisk species have met limited success (4, 5).

Where species have high economic value (such as in the case of the Chinese cave gecko), withholding information may be the only option. Relevant government or regulatory agencies should be notified of scientific discoveries, and pathways for access from legitimate persons remain open. In moderate risk situations, spatial data might be buffered and only very broad location data provided. Where there is low risk of perverse outcomes, unrestricted publication of habitat descriptions and location information remains appropriate (see the figure).

Much information on endangered and newly described species can still be published without location data being provided and without undermining the integrity or repeatability of the scientific work [akin to the notion that the rediscovery of Lazarus species can be validated without the collection of voucher specimens (10)]. As such, negative trade-offs arising from the dual-use research dilemma are not as pronounced as in other fields. For example, restrictions on publishing methodological advances in the study of pathogen virulence can inhibit scientific research that can have considerable human health benefits but is sometimes deemed necessary because of the potential for this information to facilitate perverse outcomes (such as bioterrorism) (11, 12).

Endangered or newly discovered species can be at risk from poachers if their location data is published. This scheme helps to assess whether publication should be restricted in particular cases.

Some fields such as paleontology and archaeology have long maintained restrictions on the publication of site locations and promoted government policies and regulations to limit collection and trade in fossils, artefacts, and culturally sensitive and/or scientifically important material (13). Organizations such as the U.S. Forest Service do not disclose geospatial data in order to protect research sites (14). Other solutions include modification of research permits so that endangered species locations are not automatically uploaded into wildlife databases and masking such records on private land, as presently occurs in some states in the United States. Some of these approaches are already in place in conservation; for example, the open-access journal PLOS ONE has data exemptions for endangered species. However, current policies are specific to individual journals, data repositories, or organizations and lack consistent enforcement. A major benefit to the author-led self-censorship that we advocate is that restrictions of the dissemination of sensitive information can be implemented widely and immediately.

There are signs that this problem is beginning to be addressed. Journals such as Zootaxa that carry taxonomic descriptions of new species now publish new descriptions without location information (15). More researchers, journal editors, and data custodians need to follow their lead. Otherwise, the potential benefits of open-access scientific information and data for biodiversity conservation will be outweighed by the perverse effects of exposing wild populations to substantial added conservation threats. Although much information on endangered and rare species is already available online, it remains crucial to change our actions now to avoid unwittingly contributing to further species declines.

Call to keep secrets on rare species draws reluctant support

By Warren Cornwall

The extent to which rare animal poachers piggyback on scientific research became clear to Mark Auliya soon after he published a 2012 paper announcing the discovery of the Borneo earless monitor lizard (Lanthanotus borneensis) in a new part of the southeast Asian island.

The conservation biologist at the Helmholtz Centre for Environmental Research in Leipzig, Germany, had left the lizards’ location vague, in an attempt to shield the animal from collectors and their suppliers. Nevertheless, within a year, the lizard was turning up outside Borneo.
After scientists published a paper documenting a new 
population of earless monitor lizards in Borneo, poachers
 moved in.

So Auliya embraces a new call, published today in Science, for scientists to keep mum about details that could turn rare and sought-after species into the next easy target for the global wild animal trade. “It’s terrible,” he says. “If you describe a new species in the Democratic Republic of Congo, you should probably only list the country.” In today’s Perspective, two Australian conservation biologists urge scientists to adopt a policy of strategic “self-censorship” to shield the animals and plants they study. For species that are likely targets for collectors, they urge scientists to share detailed information about where the species is found only with government agencies, while hiding it from the public.

Such secrecy runs counter to the imperative to share research with the scientific world, and the push to make it quickly and widely available. But that openness is taking a devastating toll, says David Lindenmayer, the article’s lead author and a conservation biologist at The Australian National University in Canberra.  “For some of the really important species, if we don’t do something they’re going to get wiped off the map.”

He was alerted to the intensity of the problem in 2016, when he got a call from a landowner about people tearing apart rocky outcrops with crowbars. Lindenmayer figured out that the interlopers were on the hunt for the rare pink-tailed worm-lizard (Aprasia parapulchella), a bizarre legless gecko that grows to 15 centimeters, spends its life in rocky fissures in Australia, feeds on ants, and squeaks when picked up. The animal’s location at the farm was first reported just weeks earlier, from information the government requires Lindenmayer to provide in an open-access online database.

Since then, he has gathered accounts from fellow scientists about a host of species targeted for poaching shortly after their discovery was published. He fears that this pressure has only increased as new scientific research becomes available to the world with the click of a mouse. “The era of online data, of open-access data, data in real time, all those kinds of things, opens up a whole new set of opportunities for people who want to poach animals,” he says.

This entanglement of science and poaching isn’t new, says Mark Burgman, a conservation biologist at Imperial College London, and editor-in-chief of the journal Conservation Biology. Neither is the use of scientific subterfuge to foil thieves. The pressure is acute for rare or unusual species sought by collectors: amphibians, orchids, birds, and reptiles—particularly venomous snakes. One paper he published about the discovery of a plant included a map that had been manipulated to make the location indiscernible. He worked with the journal to create the altered map. In Australia in the 1980s, he managed a database for state government that listed the locations of certain species only down to within roughly a hundred kilometers, to make them harder to find.

Burgman says secrecy should be handled on a case-by-case basis between scientists and sources of scientific information, such as journals. Any secret information can be revealed to other scientists or government officials on a need-to-know basis.

But there are drawbacks to shielding new data, says Bryan Stuart, a herpetologist at the North Carolina Museum of Natural Sciences in Raleigh. Information about a species’ location can be crucial to guiding conservation efforts. And such information can still leak out through avenues such as museum collections, he says. “I believe that withholding locality data is only a temporary measure,” he wrote in an email.

Stuart co-wrote a 2006 letter in Science urging scientists to try to address the poaching problem by working closely with conservation managers to have protections for the species in place when the research is published. He acknowledges, however, that this approach won’t always succeed.

Auliya, meanwhile, hopes the new attention might revive his attempt to host a workshop where scientists can hash out guidelines for how to publish their findings without imperiling the very species they are studying. In 2012 he tried to arrange such a gathering, but couldn’t get it funded. 

Thursday, May 25, 2017

Cuban boas coordinate their hunting behavior

Snakes have long been thought to be solitary hunters. A new study from the University of Tennessee, Knoxville, shows that the Cuban boa (Chilabothrus angulifer) coordinate their hunts to increase their chances of success. Vladimir Dinets, a research assistant professor of psychology at the University of Tennessee, observed Cuban Boa's hunting behavior in bat caves. Many Cuban caves shelter large bat colonies, and in some of them small populations of boas regularly hunt bats as they fly out at dusk and return at dawn. Dinets noticed that the boas hung down from the ceiling of the cave entrance and grabbed passing bats in midair. He found that if more than one boa was present, the snakes coordinated their positions in such a way that they formed a wall across the entrance. This made it difficult or impossible for the bats to pass without getting within striking distance of at least one boa. Such group hunts were always successful, and the more snakes present the less time it took each to capture a bat. But if there was only one boa, it sometimes failed to secure a meal. These findings were recently published open-access in the journal Animal Behavior and Cognition. To date, only a handful of snakes have been observed hunting in groups, and coordination among them -- or among any other group-hunting reptiles -- has never been proven, Dinets said. Only a few of the world's 3,650 snake species have ever been observed hunting in the wild, so very little is known about snakes' diverse hunting tactics. "It is possible that coordinated hunting is not uncommon among snakes, but it will take a lot of very patient field research to find out," Dinets said. He added that observing the Cuban boa, although an amazing spectacle, is becoming increasingly difficult since only the most remote caves still have boas. The boas are being hunted for food and possibly pet trade. "I suspect that if their numbers in a cave fall, they can't hunt in groups anymore and might die out even if some of them don't get caught by hunters," Dinets said. "A few of these caves are in national parks, but there's a lot of poaching everywhere."




Citation

 Dinets V. 2017. Coordinated hunting by Cuban boas. Animal Behavior and Cognition, May 2017 DOI: 10.12966/abc.02.02.2017

Coral snake mimic loses pattern in absences of coral snake model

Tobago's Erythrolamprus ocellatus above. Trinidad's coral snake 
mimic E.  
aesculapii below.
Losses of adaptations in response to changed selective pressures are evolutionarily important phenomena but relatively few empirical examples have been investigated in detail. To help fill this gap, Hodson and Lehtinen took advantage of a natural experiment in which coral snake mimics occur on two nearby tropical islands, one that has coral snake models (Trinidad) and one that lacks them (Tobago).

The Tobago snake's pattern represents a loss of an adaptation in response to changed selective pressures. Relatively few empirical examples of adaptation loss have been investigated in detail. Hodson and Lehtinen took advantage of a natural experiment in which coral snake mimics occur on two nearby tropical islands, one that has coral snake models (Trinidad) and one that lacks them (Tobago). On Tobago, an endemic coral snake mimic (Erythrolamprus ocellatus) exists but has a relatively poor resemblance to coral snakes. Quantitative image analysis of museum specimens confirmed that E. ocellatus is a poor mimic of coral snakes.

To address questions related to the functional importance of this phenotype, the authors conducted a field experiment on both islands with snake replicas made of clay. These results clearly indicated a strong inter-island difference in predator attack rates where snake replicas that resembled coral snakes received protection in Trinidad but not in Tobago. Color patterns from museum specimens confirmed that E. ocellatus is indeed a poor mimic of coral snakes in many respects, especially in regards to the relative proportions of colors and the lack of discrete band. This implies that the classic coral snake mimicry adaptation has been degraded in this species. Field experiment revealed that E. ocellatus replicas were not protected from predator attacks on Tobago (where no coral snakes occur) compared to controls. However, on Trinidad (where coral snakes do occur) we found the expected lower attack rate on coral snake and mimic replicas compared to controls. Thus, E. ocellatus does not just look like a poor mimic to human eyes, its predators show no evidence of avoiding it.

Further, a molecular phylogenetic analysis of the ancestry of E. ocellatus revealed that this poor coral snake mimic is deeply nested in a clade of good coral snake mimics. Therefore the lack of coral snakes on Tobago altered the selective environment such that the coral snake mimicry adaptation was no longer advantageous. The failure to maintain this ancestral feature in allopatry provides a compelling example of how losses of complex adaptations can occur.

Citation
Hodson EE, Lehtinen RM. 2017. Diverse Evidence for the Decline of an Adaptation in a Coral Snake Mimic. Evolutionary Biology. 2017:1-0.

Monday, May 22, 2017

The last European varanid

The Desert Monitor, Varanus griseus is the extant species
with the closest distribution to Europe today
In a recent paper, Georgalis et al. (2017) report the remains of a varanid lizard from the middle Pleistocene of the Tourkobounia 5 locality near Athens, Greece. The new fossil material comprises cranial elements only (one maxilla, one dentary, and one tooth) and is attributed to the monitor lizard genus Varanus, the genus to which all European Neogene varanid remains have been assigned. Previously, the most recent undisputed varanid from Europe had been recovered from upper Pliocene sediments. The new Greek fossils, therefore, constitute the most recent records of monitor lizards from the continent. Despite being incomplete, this new material enhances our understanding of the cranial anatomy of the last European monitor lizards and is clearly not referable to any of the extant species such as Varanus griseus or Varanus niloticus - the only species that could be taken into consideration on a present-day geographic basis. However, these fossils could represent a survivor of the monitor lizards of Asian origin that inhabited Europe during the Neogene. Varanids first appear in the European fossil record during the Eocene. They are entirely absent from the European Oligocene faunas but appear again in the fossil record after the early Miocene. It is possible the European Paleogene varanids were victims of the Grande Coupure. The Grande Coupure refers to a break or change in faunal continuity about 33.5 MYA and marks the the end of the Eocene assemblages of mammals, with the arrival of Asian species in Europe. The authors note that on the basis of the available data this cannot be demonstrated with certainty. All of the Neogene European varanids appear to be members of Varanus, and they seem to have dispersed into Europe in the early Miocene. In fact, the earliest evidence of the genus on the European continent is recorded in the early Miocene of Spain. Whether these early Miocene immigrants originated directly from Africa or have Asian affinities cannot be demonstrated with certainty. The occurrence of Varanus-like forms in the late Eocene and early Oligocene of Egypt favors an African origin, but the Asian record is too weak to offer any insights. The fact that the maxilla from Tourkobounia 5 does not show any relationship with extant African taxa (V. albigularis, V. exanthematicus, V. griseus, V. niloticus, V. ornatus) suggests Asian affinities, as already reported for the extinct Varanus amnhophilis from the late Miocene of Samos. Whatever their exact origin, monitor lizards rapidly achieved a wide distribution throughout Europe during the Miocene. Fossils attributed to this genus have been described from localities in Austria, Germany, Greece, Hungary, Italy, Moldova, Portugal, Romania, Spain, and the Ukraine.

Citation

Georgalis, G. L., A. Villa, and M. Delfino. 2017. The last European varanid: demise and extinction of monitor lizards (Squamata, Varanidae) from Europe. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2017.1301946.

Sunday, May 21, 2017

Some monitor lizards have not recovered from the introduction of the cane toad

Varanus panoptes Image credit: Greg Hume

The impact of invasive species is often underestimated by many. However, invasives can trigger trophic cascades in animal communities but published cases documenting the results of removing top predators are extremely rare. An exception is the invasive cane toad (Rhinella marina) in Australia, which has caused severe population declines in monitor lizards, triggering trophic cascades that facilitated dramatic and sometimes unexpected increases in several prey of the predators, including smaller lizards, snakes, turtles, crocodiles, and birds. Persistence of isolated populations of predators with a decades-long co-existence with toads suggests the possibility of recovery, but alternative explanations are possible. In a new paper, Doody et al. (2017)  note that confirming predator recovery requires longer-term study of populations with both baseline and immediate post-invasion densities. The authors had previously quantified the short-term impacts of the invasive cane toads over seven years at two sites in tropical Australia. In the new paper, they test the hypothesis that predators have begun to recover by repeating the study 12 years after the initial toad invasion. The three predatory lizards (Varanus panoptes, V. mertensi, V. mitchelli) that experienced 71-97% declines in the short-term study showed no sign of recovery, and indeed a worse fate. Two of the three species  (Varanus panoptes and V. mitchelli) were no longer detectable in 630 km of river surveys, suggesting local extirpation. Two mesopredators that had increased markedly in the short-term due to the above predator losses showed diverse responses in the medium-term; a small lizard species increased by about 500%, while populations of a snake species showed little change. Their results indicate a system still in ecological turmoil, having not yet reached a ‘new equilibrium’ more than a decade after the initial invasion; predator losses due to this toxic invasive species, and thus downstream effects, were not transient. Given that cane toads have proven too prolific to eradicate or control, we suggest that recovery of impacted predators must occur unassisted by evolutionary means: dispersal into extinction sites from surviving populations with alleles for toxin resistance or toad avoidance. Evolution and subsequent dispersal may be the only solution for a number of species or communities affected by invasive species for which control is either prohibitively expensive, or not possible.

Citation
Doody JS, Rhind D, Green B, Castellano C, McHenry C, Clulow S. 2017. Chronic effects of an invasive species on an animal community. Ecology. 2017 May 6.