Christina M. Romagosa

Severe mammal declines coincide with proliferation of invasive Burmese pythons in Everglades National Park

Invasive species represent a significant threat to global biodiversity and a substantial economic burden. Burmese pythons, giant constricting snakes native to Asia, now are found throughout much of southern Florida, including all of Everglades National Park (ENP). Pythons have increased dramatically in both abundance and geographic range since 2000 and consume a wide variety of mammals and birds. Here we report severe apparent declines in mammal populations that coincide temporally and spatially with the proliferation of pythons in ENP. Before 2000, mammals were encountered frequently during nocturnal road surveys within ENP. In contrast, road surveys totaling 56,971 km from 2003–2011 documented a 99.3% decrease in the frequency of raccoon observations, decreases of 98.9% and 87.5% for opossum and bobcat observations, respectively, and failed to detect rabbits. Road surveys also revealed that these species are more common in areas where pythons have been discovered only recently and are most abundant outside the pythons current introduced range. These findings suggest that predation by pythons has resulted in dramatic declines in mammals within ENP and that introduced apex predators, such as giant constrictors, can exert significant top-down pressure on prey populations. Severe declines in easily observed and/or common mammals, such as raccoons and bobcats, bode poorly for species of conservation concern, which often are more difficult to sample and occur at lower densities.

Contribution of the Live‐Vertebrate Trade toward Taxonomic Homogenization

The process of taxonomic homogenization occurs through two mechanisms, extinctions and introductions, and leads to a reduction of global biodiversity. We used available U.S. trade data as a proxy for global trade in live vertebrates to assess the contribution of trade to the process of taxonomic homogenization. Data included all available U.S. importation and exportation records, estimation of extinction risk, and reports of establishment outside the native range for species within six vertebrate groups. Based on Monte Carlo sampling, the number of species traded, established outside of the native range, and threatened with extinction was not randomly distributed among vertebrate families. Twenty-eight percent of vertebrate families that were traded preferentially were also established or threatened with extinction, an unusually high percentage compared with the 7% of families that were not traded preferentially but that became established or threatened with extinction. The importance of trade in homogenization of vertebrates suggests that additional efforts should be made to prevent introductions and extinctions through this medium.

Integrating invasion and disease in the risk assessment of live bird trade.

Abstract Aim International trade in plants and animals generates significant economic benefits. It also leads to substantial unintended impacts when introduced species become invasive, causing environmental disturbance or transmitting diseases that affect people, livestock, other wildlife or the environment. Policy responses are usually only implemented after these species become established and damages are already incurred. International agreements to control trade are likewise usually based on selection of species with known impacts. We aim to further develop quantitative invasive species risk assessment for bird imports and extend the tool to explicitly address disease threats. Location United States of America. Methods We use a two‐step approach for rapid risk assessment based on the expected biological risks due to both the environmental and health impact of a potentially invasive wildlife species in trade. We assess establishment probability based on a model informed by historical observations and then construct a model of emerging infectious disease threat based on economic and ecological characteristics of the exporting country. Results We illustrate how our rapid assessment tool can be used to identify high‐priority species for regulation based on a combination of the threat they pose for becoming established and vectoring emerging infectious diseases. Main conclusions Our approach can be executed for a species in a matter of days and is nested in an economic decision‐making framework for determining whether the biological risk is justified by trade benefits.

Emerging issues along urban–rural interfaces: an introduction to the special issue

Contemporary urbanization and other types of human-associated land conversion are increasing at an unprecedented rate in many parts of the world (Seto et al. 2010). This process rapidly changes environmental conditions along the edge of the urban–rural interface and leads to a set of complex issues in which the negative economic, societal, and ecological effects of land-use change must be balanced with the positive social and economic benefits (Foley et al. 2005). Over time, it has been recognized that to address the challenges presented by the issues necessitates a multi-disciplinary approach (Nilsson et al. 2003). How we effectively create policies to address these challenges depends on a foundation of knowledge provided by the scientific community. In 2005, the first Emerging Issues Along Urban–Rural Interfaces (URI): Linking Science and Society Conference was held to integrate various disciplines under one umbrella so that researchers and other interested parties could share knowledge about the issues facing other countries and disciplines. The URI Conference was held again in 2007 and 2010, with participation of researchers, practitioners, educators, and policymakers from Africa, Asia, Australia, Europe, and North and South America. Objectives for this conference series were to (1) facilitate discussion and sharing of perspectives by stakeholders from around the world and (2) foster interdisciplinary linkages that better address the complex ramifications of urbanization. This conference series is timely, coinciding with an increase in global research on this topic. A simple bibliometric analysis of the search words “urban*”, “land-use”, and “change*” in the Web of Science® (WoS; accessed 31 Dec 2012) reflects an increase in the presence of these terms and the breadth of research areas defined by WoS. A search for these terms from the 20-year span between 1974 and 2004, yielded 784 papers from 55 research areas. A search for the same terms from the subsequent 7-year span (2005 to 2012) yielded an additional 2,553 papers from 86 research areas. Urban Ecosyst (2013) 16:1–2 DOI 10.1007/s11252-013-0299-y

Parasite spillover: indirect effects of invasive Burmese pythons

Abstract Identification of the origin of parasites of nonindigenous species (NIS) can be complex. NIS may introduce parasites from their native range and acquire parasites from within their invaded range. Determination of whether parasites are non‐native or native can be complicated when parasite genera occur within both the NIS’ native range and its introduced range. We explored potential for spillover and spillback of lung parasites infecting Burmese pythons (Python bivittatus) in their invasive range (Florida). We collected 498 indigenous snakes of 26 species and 805 Burmese pythons during 2004–2016 and examined them for lung parasites. We used morphology to identify three genera of pentastome parasites, Raillietiella, a cosmopolitan form, and Porocephalus and Kiricephalus, both New World forms. We sequenced these parasites at one mitochondrial and one nuclear locus and showed that each genus is represented by a single species, R. orientalis, P. crotali, and K. coarctatus. Pythons are host to R. orientalis and P. crotali, but not K. coarctatus; native snakes are host to all three species. Sequence data show that pythons introduced R. orientalis to North America, where this parasite now infects native snakes. Additionally, our data suggest that pythons are competent hosts to P. crotali, a widespread parasite native to North and South America that was previously hypothesized to infect only viperid snakes. Our results indicate invasive Burmese pythons have affected parasite‐host dynamics of native snakes in ways that are consistent with parasite spillover and demonstrate the potential for indirect effects during invasions. Additionally, we show that pythons have acquired a parasite native to their introduced range, which is the initial condition necessary for parasite spillback.

Toxic, invasive treefrog creates evolutionary trap for native gartersnakes

Possession of unique defensive toxins by nonindigenous species may increase the likelihood of creating evolutionary traps for native predators. We tested the hypothesis that nonindigenous, toxic Cuban Treefrogs (Osteopilus septentrionalis) have created an evolutionary trap for native, generalist snakes. Additionally, we explored the possibility that populations of snakes that co-occur with Cuban Treefrogs have responded in ways that allow them to escape potential trap dynamics. To evaluate a potential fitness cost of consuming Cuban Treefrogs, we monitored growth of 61 wild-caught Common Gartersnakes (Thamnophis sirtalis) fed exclusive diets of either Cuban Treefrogs, native Green Treefrogs (Hyla cinerea), or native Golden Shiners (Notemigonus crysoleucas). Snakes in the Cuban Treefrog diet treatment gained less than half the mass of those consuming native prey, and Cuban Treefrogs were significantly less digestible than native prey. There was no difference in the response of gartersnakes to prey scent cues of Cuban Treefrogs and Green Treefrogs. Our results indicate that Cuban Treefrogs likely represent an evolutionary trap for snakes because consumption of these frogs carries fitness costs, yet snakes fail to recognize this prey as being costly. We found no difference in growth or response to prey cues between snakes from invaded and non-invaded regions, suggesting snakes have not responded to escape trap dynamics. Interactions of native snakes and Cuban Treefrogs support the idea that introduced species with novel toxins may increase the likelihood of evolutionary trap formation.