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Simple Summary: Invasive species are common on islands and, increasingly so, in urban ecosystems. They can pose serious ecological and socioeconomic impacts, making research on how invasions are promoted critically important. We examined different traits of guttural toads (Sclerophrys gutturalis) in their natural and invasive ranges (both natural and urban populations in native and invasive sites) to understand if divergences in habitats in their native range could increase their invasive potential. We found that invasive island populations on Mauritius and Réunion (Indian Ocean) have reduced body sizes, proportionally shorter limbs, slower escape speeds, and reduced endurance capacities compared to the native South African populations. In short, these changes occurred post-invasion. However, increase climbing ability was seen within the urban-native toads, a trait maintained within the two invasions, suggesting that it may have been an advantageous prior adaptation. Becoming climbers may have benefited the toad during colonization, increasing navigation and hunting ability within the urbanized areas where they were introduced, prior to their spread into natural areas. This change in climbing performance is an example of how the urbanization of native taxa may be increasing the ability of certain species to become better invaders should they be introduced outside their native range. A prominent feature of the modern era is the increasing spread of invasive species, particularly within island and urban ecosystems, and these occurrences provide valuable natural experiments by which evolutionary and invasion hypotheses can be tested. In this study, we used the invasion route of guttural toads (Sclerophrys gutturalis) from natural-native and urban-native populations (Durban, South Africa) to their urban-invasive and natural-invasive populations (Mauritius and Réunion) to determine whether phenotypic changes that arose once the toads became urbanized in their native range have increased their invasive potential before they were transported (i.e., prior adaptation) or whether the observed changes are unique to the invasive populations. This urban/natural by native/invasive gradient allowed us to examine differences in guttural toad morphology (i.e., body size, hindlimb, and hindfoot length) and performance capacity (i.e., escape speed, endurance, and climbing ability) along their invasion route. Our findings indicate that invasive island populations have reduced body sizes, shorter limbs in relation to snout-vent length, decreased escape speeds, and decreased endurance capacities that are distinct from the native mainland populations (i.e., invasion-derived change). Thus, these characteristics did not likely arise directly from a pre-transport anthropogenic "filter" (i.e., urban-derived change). Climbing ability, however, did appear to originate within the urban-native range and was maintained within the invasive populations, thereby suggesting it may have been a prior adaptation that provided this species with an advantage during its establishment in urban areas and spread into natural forests. We discuss how this shift in climbing performance may be ecologically related to the success of urban and invasive guttural toad populations, as well as how it may have impacted other island-derived morphological and performance phenotypes. [ABSTRACT FROM AUTHOR]

The island of Newfoundland has no native amphibian taxa, although six species of Anura (i.e., frogs and toads) have been introduced since European colonisation, four of which have established self-sustaining populations. Here, we document Eastern Red-backed Salamander (Plethodon cinereus) on Newfoundland for the first time, in what appears to be a self-sustaining population near Conception Bay South. This is the first species of Caudata (i.e., newts and salamanders) to have been introduced to the island, as well as the first occurrence of Eastern Red-backed Salamander establishing a population outside its native range. The impact that this non-native species might have on forest ecosystems on Newfoundland is unclear and further study is required to determine whether eradication of the species from Newfoundland is necessary or feasible. [ABSTRACT FROM AUTHOR]

Many biological invasions occur within and between urban areas. If native species adapted to anthropogenically altered habitats are subsequently moved from an urban area in their native range to one within a novel region, then their urban-specialized phenotypes may provide them an advantage via prior adaptation. Here we examine if urban-derived behavioral traits are present within native guttural toad, Sclerophrys gutturalis, populations (Durban, South Africa) and investigate whether these localized phenotypes persisted within their invasive populations in Mauritius and Réunion. In our study, we measured boldness and exploration in populations along the toad's invasion route and found that toads were significantly bolder in urban populations, within both native and invasive ranges. This suggests boldness increased when toads transitioned to urban living in their native range and these heightened levels of boldness were maintained within invaded urban areas. This provides evidence that a bolder phenotype was a prior adaptation that likely increased guttural toad's invasion success. Interestingly, toad boldness returned to pre-urbanization levels within invasive populations that spread into natural areas, replicated on both islands. Exploration, on the other hand, was not increased above pre-urbanization, or pre-invasion, levels for any of the populations, and was lower in toads from Mauritius. Overall, our findings suggest that increased boldness is favored in urban habitats and that urban-derived behavioral traits may provide individuals an advantage when invading new urban landscapes. Significance statement: Species adapting to anthropogenic landscapes have the ability to increase their invasive potential if the altered phenotypes they accrue can provide them advantages once they are transported outside their native range. Our study examined differences in behavioral traits, boldness, and exploration, along the invasion route of guttural toads, Sclerophrys gutturalis, between natural and urban sites from their native origin populations around Durban, South Africa, to their invasive populations in Mauritius and Réunion. We determined that populations were bolder in urban areas in their native range and that this increased boldness persisted in the other anthropogenic habitats within their invasive ranges, but reverted back to natural-native levels within populations that had spread into natural areas on both islands. Our findings support the growing trend that anthropogenically altered landscapes favor bolder individuals, as well as the assertion that urban-derived traits may bolster a species' ability to establish and spread within novel landscapes. [ABSTRACT FROM AUTHOR]

The invertebrate communities of Mauritius host a high degree of endemism, but are also imperilled by an array of factors, including invasive predators. Since their introduction in 1922, guttural toads (Sclerophrys gutturalis) have spread across the island and have been implicated in the decline of a number of endemic invertebrate species. In this study, we examined the feeding habits of the invasive population of guttural toads from three naturally forested locations in Mauritius across multiple years by analysing their stomach content. We also measured the relative abundance of prey items on the landscape using pitfall traps and applied these data to determine prey preference using a Relativised Electivity Index. Insects, malacostracans and gastropods constituted the bulk of the toads' diet (48.7%, 33.4% and 11.8%, respectively), which also included several rare and endemic species. We further determined that insects and malacostracans were also the two most favoured prey taxa, relative to what was available on the landscape. Our investigation has generated several recommendations for future research and provides a fundamental understanding of the diet of guttural toads in the native forests of Mauritius. [ABSTRACT FROM AUTHOR]

Invasion Biology is a young discipline, Charles Elton only coined the term in 1958. Although the subject was generally ignored by most people for 40 years, the last 20 years has seen a near exponential rise in papers by herpetologists on alien reptiles and amphibians (and not only by Rick Shine!). But how do herpetologists go about studying invasions? In this study, we reviewed 836 publications on alien herps and compared their objectives with 30 well known hypotheses from invasion biology. We found that although the field is rapidly expanding, very few researchers had specified any of the invasion hypotheses, but 26% had the data to test one or more. The most commonly tested hypothesis resembled the concept of the 'ideal weed', that invasion success of a non-native species depends on its specific traits (3.8%). Other popular hypotheses referred to habitat filtering (1.7%), preadaptation through human commensalism (1.8%), novel weapons (1.3%), novel associations (1.4%) and invasion meltdown (1.5%). Perhaps more excitingly, are the new hypotheses that herpetologists can donate to invasion biology, including spatial sorting, invasion hubs and hybridisation. We conclude that herpetologists need to pay more attention to existing hypotheses in invasion biology, many of which stem from classical questions in ecology. Better transdisciplinary communication will likely lead to increased impact of studies which could teach invasion biologists more about reptiles, amphibians and their amazing invasions. [ABSTRACT FROM AUTHOR]