Christian A. Perez-Martinez

Los cambios en el tamaño corporal afectan el comportamiento de los organismos y pueden facilitar nuevas interacciones ecológicas. En la herpetofauna, la miniaturización ha evolucionado de manera independiente en múltiples ocasiones; sin embargo, la historia natural de las especies miniaturizadas ha sido poco estudiada. Reportamos evidencia de oviposición por la salamanquita común (Sphaerodactylus grandisquamis guarionex) en las conchas vacías del caracol arbóreo puertorriqueño (Caracolus carocolla). Nuestras observaciones se realizaron en el bosque húmedo subtropical de la Reserva Natural Mata de Plátano, localizada en la región del carso del noroeste de Puerto Rico. Muestreos de la hojarasca produjeron tres observaciones de huevos de S. g. guarionex en lo más profundo de los verticilos de tres conchas de caracol, así como fragmentos de huevo en cinco caracoles adicionales. Los tres huevos intactos de S. g. guarionex eran viables y eclosionaron entre 11 y 31 días. El uso de conchas de caracoles terrestres como lugares de oviposición o refugios se ha reportado con mayor frecuencia en artrópodos. Además, reportamos la presencia de nidos de hormigas, escorpiones, opiliones, arañas y grillos dentro de las conchas de C. carocolla. Sin embargo, los reportes de oviposición en conchas de caracoles son sumamente raros en reptiles y anfibios. Por el momento, solo se ha documentado en gecos del registro fósil y en dos especies de anuros. Presentamus una síntesis de la selección de sitios de oviposición en el género Sphaerodactylus y proponemos varias hipótesis que pueden explicar nuestras observaciones. Dada la alta diversidad y abundancia de caracoles terrestres en las islas del Caribe, especulamos que la oviposición de especies de Sphaerodactylus en conchas de caracoles puede ser un fenómeno más frecuente de lo que se reconoce actualmente.

Traditional sampling methods have limited our understanding of the behavioral ecology of leaf litter fauna. Substrate-borne vibrations provide a window that addresses this shortcoming. Under natural conditions, we implemented a passive monitoring system that measures vibrations produced by two miniaturized Puerto Rican geckos: Sphaerodactylus grandisquamis in the mesic karst forest and Sphaerodactylus townsendi in the coastal dry forest. The dichotomy between habitats allowed us to test the hypothesis that microclimate conditions drive divergence in thermoregulatory behavior. For each species in its native habitat, thirty individuals were monitored inside a field enclosure, excluding other vibration sources. We measured vibrations at two strata depths (i.e., surface and bottom) to characterize behavioral responses to diel cycle, microclimate, and predatory bird calls. Vibrational data revealed contrasting activity patterns across strata. Mesic S. grandisquamis showed continuous daytime activity at all strata levels, regardless of microclimate. Dry forest S. townsendi featured a biphasic activity pattern, peaking midday and at dusk, and increased activity in deeper litter strata during hot and dry conditions (i.e., midday). Analysis at fine temporal scales for S. grandisquamis revealed a reduction in surface activity after the onset of bird calls from three species that pose a predation risk. Our results demonstrate interspecific differences in thermoregulatory behavior that likely increase the fitness of each species in their respective habitats. Furthermore, vibrational monitoring strongly suggests Sphaerodactylus exploit their niche in a three-dimensional manner, mirroring habitat use patterns of arboreal fauna and highlighting the importance of incorporating multiple strata levels when studying leaf litter microhabitats.

High-resolution imaging, 3D modeling, and quantitative analyses are equipping evolutionary biologists with new approaches to understanding the variation and evolution of the musculoskeletal system. However, challenges with interpreting DiceCT data and higher order use of modeled muscles have not yet been fully explored, and the error in and accuracy of some digital methods remain unclear. West Indian Anolis lizards are a model clade for exploring patterns in functional adaptation, ecomorphology, and sexual size dimorphism in vertebrates. These lizards possess numerous jaw muscles with potentially different anatomies that sculpt the adductor chamber of the skull. Here we test approaches to quantifying the musculoskeletal shape of the heads of two species of Anolis: A. pulchellus and A. sagrei. We employ comparative approaches such as DiceCT segmentation of jaw muscles, 3D surface attachment mapping, and 3D landmarking with the aim of exploring muscle volumes, 3D muscle fiber architecture, and sexual dimorphism of the skull. We then compare sources of measurement error in these 3D analyses while also presenting new 3D musculoskeletal data from the Anolis feeding apparatus. These findings demonstrate the accessibility and repeatability of these emerging techniques as well as provide details regarding the musculoskeletal anatomy of the heads of A. pulchellus and A. sagrei which show potential for further research of comparative biomechanics and evolution in the clade.

Thirteen species of West Indian boas (Chilabothrus) are distributed across the islands of the Greater Antilles and Lucayan Archipelago. Hispaniola is unique among this group of islands in having more than two species of Chilabothrus—three are currently recognized. Here we describe a fourth species from Hispaniola, a newly discovered distinctive species of small boa from the dry forest of the Barahona Peninsula, southwestern Dominican Republic, near the border with Haiti. This new species resembles in body size and in other aspects its closest relative Chilabothrus fordii (Günther 1861), with which it appears to be allopatric. The new species, which we describe as Chilabothrus ampelophis sp. nov., differs from C. fordii in body, head, and snout shape; in scalation; in both coloration and color pattern; and in phylogenetic uniqueness. Some relevant meristic characters from C. ampelophis sp. nov. fall between C. fordii and C. gracilis (Fischer 1888), accentuating the morphological and likely ecological differences from its sister species C. fordii. The discovery of this new species is especially important as it appears to be among the smallest boid (Boidae) species, has an arboreal specialization, and is found in a very restricted and highly threatened habitat.

Extreme body size reductions bring about unorthodox anatomical arrangements and novel ways in which animals interact with the environment. Drawing from studies of vertebrates and invertebrates, we provide a theoretical framework for miniaturization to inform hypotheses using lizards as a study system. Through this approach, we demonstrate the repeated evolution of miniaturization across 11 families and a tendency for miniaturized species to occupy terrestrial microhabitats, possibly driven by physiological constraints. Differences in gross brain morphology between two gecko species demonstrate a proportionally larger telencephalon and smaller olfactory bulbs in the miniaturized species, though more data are needed to generalize this trend. Our study brings into light the potential contributions of miniaturized lizards to explain patterns of body size evolution and its impact on ecology and neuroanatomy. In addition, our findings reveal the need to study the natural history of miniaturized species, particularly in relation to their sensory and physiological ecology.

Describing the relationships among morphology, behavior, and ecology is central to understanding the processes of evolutionary diversification. Anolis lizards are an excellent group for studying such ecomorphological relationships. Extensive research on anole ecological morphology has been conducted in the Caribbean, where sympatric species have repeatedly and convergently evolved to partition habitat through differential perch use. Six ecomorphs have been described, each with particular behavioral, morphological, and ecological characteristics well-suited for the microhabitat it occupies. However, little research has been conducted in mainland Central or South America, and a few case studies suggest that mainland anoles may not conform to the ecomorph classes recognized for Greater Antillean anoles. In this study, we examine the ecological morphology of sympatric mainland species of Anolis in a tropical lowland rainforest in Costa Rica and compare these species to the Caribbean ecomorphs. Our results show overlapping niches and substantial variability in habitat use across many species. Moreover, the relationship between relative hindlimb morphology and habitat use in Anolis humilis and Anolis limifrons does not conform to that of Caribbean species. Predation and fluctuating environmental conditions likely structure morphological variation differently in the mainland, leading the independent radiation of mainland anoles to produce divergent ecomorphological relationships compared with the Caribbean islands.

When faced with a predator, some animals engage in a deimatic display to startle the predator momentarily, resulting in a pause or retreat, thereby increasing their chance of escape. Frillneck lizards (Chlamydosaurus kingii) are characterised by a large, pronounced frill that extends from the base of the head to beyond the neck and, when displayed, can be up to six times the width of the head. We used behavioural assays with a model avian predator to demonstrate that their display conforms to deimatic display theory. First, juveniles and adults deployed the frill in encounters with a model predator. Second, the display revealed three colour patches (white and red–orange patches on the frill; yellow mouth palate) that facilitate a transition from a cryptic to a conspicuous state as perceived by a raptor visual system. Third, the display was performed with movements that amplified its effect. The frill area was larger in males than in females, which suggests that the frill might also be co-opted for male–male contests. If future research confirms a role of the frill in male agonistic interactions, frillneck lizards will be a rare case in which a structure has a dual function in a deimatic display and a sexually selected signal.