Mason J. Ryan

ANCIENT COLONIZATION PREDICTS RECENT NATURALIZATION IN ANOLIS LIZARDS

The distributions and characteristics of naturalized species may be explained by novel anthropogenous aspects of world biogeography such as the creation of favorable transport environments for propagules on ships. Conversely, the unprecedented connectivity of humans may simply accelerate omnipresent ecological and evolutionary forces, for example, ships may allow species that are generally good dispersers to disperse more quickly. As a null hypothesis, there may be no human component to species naturalization. The first hypothesis predicts that naturalized species will possess unusual characteristics specific to interactions with humans. The latter two hypotheses predict similarity between ancient colonizers and recently naturalized species. In this article, we present a test of the latter hypotheses and show how they may be reconciled with the former. We show that species of Anolis lizard that are ancient solitary colonizers share characteristics of size, shape, scalation, and phylogeny with naturalized species of Anolis. Characteristics of ancient solitary colonizers predict naturalization approximately as well as characteristics of naturalized species themselves. These results suggest the existence of a general colonizing type of Anolis, and that contemporary patterns of naturalization are at least partially explained by abilities that are unrelated to interactions with humans.

Too dry for lizards: short-term rainfall influence on lizard microhabitat use in an experimental rainfall manipulation within a piñon-juniper

Summary 1.Ectotherms such as lizards are expected to alter their behavior and microhabitat use and experience population declines in response to rising temperatures. But the role of changing rainfall patterns on lizard behavior and microhabitat use is not understood. 2.We used a 5-year rainfall manipulation experiment in a pinon pine-juniper woodland in central New Mexico to study how a lizard species’ microhabitat use varies in four different rainfall treatments. 3.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. 4.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. 5.Our study shows that rainfall can influence lizard microhabitat use more than temperature in a pinon pine-juniper woodland and the trees provide important refugia. The loss of pinon pine and juniper trees from prolonged drought threatens to limit the amount of shade available to lizards in the future. This article is protected by copyright. All rights reserved.

Rediscovery of the critically endangered streamside frog, Craugastor taurus (Craugastoridae), in Costa Rica

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

Too wet for frogs: changes in a tropical leaf litter community coincide with La Nina

Extreme climatic events such as the El Nino Southern Oscillation profoundly affect many plants and animals, including amphibians, which are strongly negatively affected by drought conditions. How amphibians respond to exceptionally high precipitation as observed in La Nina events, however, remains unclear. We document the correlation between the exceedingly wet 2010-2012 La Nina and community-level changes in a leaf litter frog assemblage in Costa Rica. Relative abundances of species shifted, diversity and plot occupancy decreased, and community composition became homogenized with the onset of La Nina. These aspects remained altered for over 20 months but rebounded to pre-La Nina levels after approximately 12 months. We hypothesize that complex ecological cascades associated with excess moisture caused short-term declines in abundances of species and associated changes in community structure. If additional stressors such as disease or habitat loss are not co-occurring, frog communities can rapidly recover to pre-disturbance levels following severe climatic events.

Individualistic population responses of five frog species in two changing tropical environments over time.

Roughly 40% of amphibian species are in decline with habitat loss, disease, and climate change being the most cited threats. Heterogeneity of extrinsic (e.g. climate) and intrinsic (e.g. local adaptations) factors across a species’ range should influence population response to climate change and other threats. Here we examine relative detectability changes for five direct-developing leaf litter frogs between 42-year sampling periods at one Lowland Tropical Forest site (51 m.a.s.l.) and one Premontane Wet Forest site (1100 m.a.s.l.) in southwest Costa Rica. We identify individualistic changes in relative detectability among populations between sampling periods at different elevations. Both common and rare species showed site-specific declines, and no species exhibited significant declines at both sites. Detection changes are correlated with changes in temperature, dry season rainfall, and leaf litter depth since1969. Our study species share Least Concern conservation status, life history traits, and close phylogenetic relationship, yet their populations changed individualistically both within and among species. These results counter current views of the uniformity or predictability of amphibian decline response and suggest additional complexity for conservation decisions.

A New Species of the Craugastor rugulosus Series (Anura: Craugastoridae) from West-Central Panama

Abstract We describe a new species of anuran from the Cordillera Central, El Copé, Coclé Province, Panama. The species is assigned to the Craugastor rugulosus species series of Neotropical stream-dwelling frogs, which contains 33 species and which ranges from Mexico to central Panama. The new species differs from all other members of the C. rugulosus species series by the combination of the absence of vocal slits and nuptial pads, and the presence of strong toe webbing and a large flap-like tarsal fold. This species experienced population declines in central Panama in 2004 and no remaining populations are known.

Comparative Evolution of an Archetypal Adaptive Radiation: Innovation and Opportunity in Anolis Lizards

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.

New Species of Pristimantis (Anura: Terrarana: Strabomantinae) from Lower Central America

Abstract We describe a new species of Pristimantis in the subgenus Hypodictyon ridens Species Series from the type locality in Parque Nacional General de División Omar Torrijos Herrera on the Cordillera Central in central Panama. This species is similar to Pristimantis caryophyllaceus but can be differentiated from that form by snout–vent length (female Pristimantis educatoris ∼ 27% larger than P. caryophyllaceus), round, globular, and projecting subarticular tubercles on all digits (not projecting in P. caryophyllaceus); finger disk covers even, round, disk pads ovoid, toe disk covers expanded and palmate, and toe pads even and broadened (finger and toe disk covers and pads rounded in P. caryophyllaceus); outer metatarsal tubercle large, elongate, and projecting (obscure and small in P. caryophyllaceus). We also report and describe female parental care of eggs.

Seasonal Shifts in Relative Density of the Lizard Anolis polylepis (Squamata, Dactyloidae) in Forest and Riparian Habitats

Abstract Seasonal abundance is known to fluctuate in many reptile species, but comparative studies of proximal macrohabitats across seasons are rare. We surveyed for differences in abundance in a common lowland Central American forest anole, Anolis polylepis, across proximal forest and riparian habitats during the wet and dry seasons in southwest Costa Rica. We found that dry-season decreases in population abundance of A. polylepis in a forest habitat are mirrored by simultaneous increases in abundance in an adjacent riparian area. This result is compatible with seasonal movements between forest and riparian macrohabitats in A. polylepis. Likely causal factors for this macrohabitat shift include increased risk of desiccation and decreased prey abundance in the forest habitat during dry periods. We briefly discuss potential conservation implications of habitat shifts to suitable microhabitats on this tropical lizard.