Mason J. Ryan

The Arizona Toad (Anaxyrus microscaphus) is restricted to riverine corridors and adjacent uplands in the arid southwestern United States. As with numerous amphibians worldwide, populations are declining and face various known or suspected threats, from disease to habitat modification resulting from climate change. The Arizona Toad has been petitioned to be listed under the U.S. Endangered Species Act and was considered “warranted but precluded” citing the need for additional information – particularly regarding natural history (e.g., connectivity and dispersal ability). The objectives of this study were to characterize population structure and genetic diversity across the species’ range. We used reduced-representation genomic sequencing to genotype 3,601 single nucleotide polymorphisms in 99 Arizona Toads from ten drainages across its range. Multiple analytical methods revealed two distinct genetic groups bisected by the Colorado River; one in the northwestern portion of the range in southwestern Utah and eastern Nevada and the other in the southeastern portion of the range in central and eastern Arizona and New Mexico. We also found subtle substructure within both groups, particularly in central Arizona where toads at lower elevations were less connected than those at higher elevations. The northern and southern parts of the Arizona Toad range are not well connected genetically and could be managed as separate units. Further, these data could be used to identify source populations for assisted migration or translocations to support small or potentially declining populations.

We describe two new species of Draconura-clade semiaquatic anoles from the central Pacific versant of Costa Rica. The two new species are similar to Anolis aquaticus in external appearance and ecology but differ from this species in male dewlap coloration and scalation. Anolis robinsoni sp. nov. and A. riparius sp. nov. differ from each other mainly in male dewlap color. All three species are distinct according to diagnostic morphological traits and a phylogenetic analysis of mitochondrial DNA sequences (669 bases of COI gene). We discuss the distribution and ecology of Anolis aquaticus and the new species.

Adaptive radiation is a widely recognized pattern of evolution wherein substantial phenotypic change accompanies rapid speciation. Adaptive radiation may be triggered by environmental opportunities resulting from dispersal to new areas or via the evolution of traits, called key innovations, that allow for invasion of new niches. Species sampling is a known source of bias in many comparative analyses, yet classic adaptive radiations have not been studied comparatively with comprehensively sampled phylogenies. In this study, we use unprecedented comprehensive phylogenetic sampling of Anolis lizard species to examine comparative evolution in this well-studied adaptive radiation. We compare adaptive radiation models within Anolis and in the Anolis clade and a potential sister lineage, the Corytophanidae. We find evidence for island (i.e., opportunity) effects and no evidence for trait (i.e., key innovation) effects causing accelerated body size evolution within Anolis. However, island effects are scale dependent: when Anolis and Corytophanidae are analyzed together, no island effect is evident. We find no evidence for an island effect on speciation rate and tenuous evidence for greater speciation rate due to trait effects. These results suggest the need for precision in treatments of classic adaptive radiations such as Anolis and further refinement of the concept of adaptive radiation.

Resistance is not futile: The fungal disease chytridiomycosis has wreaked havoc on amphibians worldwide. The disease is caused by the organism Batrachochytrium dendrobatidis and was first identified in the late 1990s. Voyles et al. revisited protected areas in Panama where catastrophic amphibian losses were recorded a decade ago (see the Perspective by Collins). Although disease theory predicts that epidemics should result in reduced pathogenicity, they found no evidence for such a reduction. Despite this, the amphibian community is displaying signs of recovery—including some species presumed extinct after the outbreak. Increased host resistance may be responsible for this recovery. Science , this issue p. 1517 ; see also p. 1458

Anolis lizards (anoles) are textbook study organisms in evolution and ecology. Although several topics in evolutionary biology have been elucidated by the study of anoles, progress in some areas has been hampered by limited phylogenetic information on this group. Here, we present a phylogenetic analysis of all 379 extant species of Anolis, with new phylogenetic data for 139 species including new DNA data for 101 species. We use the resulting estimates as a basis for defining anole clade names under the principles of phylogenetic nomenclature and to examine the biogeographic history of anoles. Our new taxonomic treatment achieves the supposed advantages of recent subdivisions of anoles that employed ranked Linnaean-based nomenclature while avoiding the pitfalls of those approaches regarding artificial constraints imposed by ranks. Our biogeographic analyses demonstrate complexity in the dispersal history of anoles, including multiple crossings of the Isthmus of Panama, two invasions of the Caribbean, single invasions to Jamaica and Cuba, and a single evolutionary dispersal from the Caribbean to the mainland that resulted in substantial anole diversity. Our comprehensive phylogenetic estimate of anoles should prove useful for rigorous testing of many comparative evolutionary hypotheses. [Anoles; biogeography; lizards; Neotropics; phylogeny; taxonomy]

Summary: Ectotherms such as lizards are expected to alter their behaviour and microhabitat use and experience population declines in response to rising temperatures. But the role of changing rainfall patterns on lizard behaviour and microhabitat use is not understood. We used a 5‐year rainfall manipulation experiment in a piñon pine‐juniper woodland in central New Mexico to study how a lizard species' microhabitat use varies in four different rainfall treatments. We examined ground temperatures in the sun and shade, and daily rainfall, within each treatment, during lizard activity periods, to address how lizards used sun or shade microhabitats on a daily basis. Our small‐scale rainfall and temperature measurements indicate that rainfall, not temperatures, predict lizard microhabitat use. Lizards showed a strong preference for shaded microhabitats during dry periods and used sunny microhabitats following rainfall events, regardless of treatment type. Lizards remained active during dry periods, foraging in the shade of trees. Our study shows that rainfall can influence lizard microhabitat use more than temperature in a piñon pine‐juniper woodland and the trees provide important refugia. The loss of piñon pine and juniper trees from prolonged drought threatens to limit the amount of shade available to lizards in the future.

The examination of the holotype of Anolis marsupialis Taylor 1956 along with recently collected specimens reveals that A. marsupialis is a valid species. It differs from its closest congeners A. humilis Peters 1863 and A. quaggulus Cope 1885, in male dewlap coloration, scalation, body size, and hemipenial morphology. These findings are supported by preliminary molecular genetic analysis.

In 1987 the amphibian decline crisis reached its apex in Costa Rica when at least 17 species experienced population crashes and subsequently went undetected for decades. The amphibian declines in Costa Rica were relatively well documented and came to exemplify the current global amphibian decline crisis. The Mesoamerica endemic frog clade, the Craugastor punctariolus species group, is one of most severely affected anuran clades, experiencing a loss of 26 out of 33 species throughout Mesoamerica. Eight species of C. punctariolus group frogs occur in Costa Rica, and all declined following the 1987 die-off; despite intensive surveys over the last 14 years, most remain undetected. To date, only one species in this group, the stream-breeding frog C. ranoides, in known to have a stable population, and only in the Santa Elena Peninsula. Here we document the rediscovery of another species, the South Pacific streamside frog C. taurus, in southeastern Costa Rica, representing the first sighting after fifteen years of searching. We discovered two previously unknown populations in Punta Banco, the driest section within the historical range, in an area representing only 4% of the historical distribution. Our findings add to the short but growing list of recently rediscovered amphibian species in Costa Rica and provide encouraging news in an otherwise discouraging situation for amphibian conservation. Additional research and monitoring are urgently needed to develop long-term management plans for this and other Critically Endangered species