Jaqueiuto da Silva Jorge

Feeding Habits and Predator-Prey Size Relationships in the Whiptail Lizard Cnemidophorus ocellifer (Teiidae) in the Semiarid Region of Brazil

ABSTRACT. We studied the diet of the whiptail lizard Cnemidophorus ocellifer (Spix, 1825) and the relationships between predator size and prey size in a Caatinga area of northeastern Brazil. Lizards (N = 111) were collected during the day through active search. In the laboratory, we measured them and registered the number of ingested items of each prey category to Order, as well as the dimensions and frequencies of each. The main prey category in the C. ocellifer diet was insect larvae and pupae, followed by Orthoptera, Isoptera, Coleoptera and Araneae. Termites (Isoptera) were important only in numeric terms, having negligible volumetric contribution and low frequency of occurrence, an uncommon feature among whiptail lizards. The types and sizes of prey consumed by adult males and females were similar, despite sexual dimorphism in head size. Adults and juveniles ingested similar prey types, but differed in prey size. Maximum and minimum prey sizes were positively correlated with lizard body size, suggesting that in this population individuals experience an ontogenetic change in diet, eating larger prey items while growing, and at the same time excluding smaller ones.

Interactive effects of predation risk and conspecific density on the nutrient stoichiometry of prey

Abstract The mere presence of predators (i.e., predation risk) can alter consumer physiology by restricting food intake and inducing stress, which can ultimately affect prey‐mediated ecosystem processes such as nutrient cycling. However, many environmental factors, including conspecific density, can mediate the perception of risk by prey. Prey conspecific density has been defined as a fundamental feature that modulates perceived risk. In this study, we tested the effects of predation risk on prey nutrient stoichiometry (body and excretion). Using a constant predation risk, we also tested the effects of varying conspecific densities on prey responses to predation risk. To answer these questions, we conducted a mesocosm experiment using caged predators (Belostoma sp.), and small bullfrog tadpoles (Lithobates catesbeianus) as prey. We found that L. catesbeianus tadpoles adjust their body nutrient stoichiometry in response to predation risk, which is affected by conspecific density. We also found that the prey exhibited strong morphological responses to predation risk (i.e., an increase in tail muscle mass), which were positively correlated to body nitrogen content. Thus, we pose the notion that in risky situations, adaptive phenotypic responses rather than behavioral ones might partially explain why prey might have a higher nitrogen content under predation risk. In addition, the interactive roles of conspecific density and predation risk, which might result in reduced perceived risk and physiological restrictions in prey, also affected how prey stoichiometry responded to the fear of predation.

Conspecific density affects predator‐induced prey phenotypic plasticity

The risk-assessment hypothesis (R-AH) states that prey must consider conspecific density and not simply the concentration of predation cues to evaluate actual predation risk. However, little is known about whether the R-AH might serve to predict predator-inducible plastic responses involving different prey phenotypes. We approached this question through an experiment in outdoor mesocosms, manipulating predation risk (with caged predators) and prey conspecific density to test the importance of R-AH for the expression of predator-induced morphological and behavioral phenotypes. We found behavioral (swimming activity) and morphological (tail width and tail muscle depth) responses of bullfrog tadpoles (Lithobates catesbeianus) to be affected by chemical predation cues. However, only the morphological phenotype responded to the predation-risk:conspecific-density interaction. The width of the tail and the muscle depth of tadpoles were significantly greater when individuals were exposed to predators. However, th...

First record of Colobosaura modesta (Reinhardt and Lütken, 1862) (Squamata: Gymnophthalmidae) to the Cariri region, state of Ceará, Brazil, with a map of its geographical distribution

We provide a new record of Colobosaura modesta for the state of Ceara and a distribution map for the species. The record for the municipality of Crato represents a distribution extension of ca . 270 km southeastern from the municipality of Crateus, Ceara, the closest known record.

Geographic distribution model for Mabuya agmosticha (Squamata: Scincidae) in northeastern Brazil

The Neotropical lizard Mabuya agmosticha Rodrigues, 2000 is a habitat-specialist of thorny bromeliads in rocky outcrops of northeastern Brazil. Its distribution in the Caatinga Domain is most likely relictual. In recent years, new surveys conducted in northeastern Brazil have revealed new records of the species in the Caatinga and also in the Atlantic Forest Domain. In this study, we add four new records for M. agmosticha, extending its known geographic range in the states of Rio Grande do Norte and Paraiba. In addition, we investigated the potential geographical distribution of the species using ecological niche modeling (ENM), which combines the available occurrence records with environmental variables. Our model revealed a continuous range of areas with suitable climatic conditions for the species, from the state of Rio Grande do Norte to the northeast portion of the state of Bahia, plus some relictual distribution spots, mainly in the states of Bahia, Pernambuco, Ceara and western Rio Grande do Norte. Based on the model, we suggest that the distribution of M. agmosticha is continuous on a large geographic scale. On a smaller spatial scale, however, it is clear that its distribution is clumped, reflecting its specialist habits associated with rupicolous bromeliads.

New record of Cercosaura ocellata Wagler, 1830 (Squamata, Gymnophthalmidae) in northeastern Brazil, with a distribution map for the species in South America

Herein, we provide a new record of Cercosaura ocellata Wagler, 1830 in the Atlantic Forest biome, northeastern Brazil, and a distribution map for the species in South America. The new record was in Extremoz municipality, state of Rio Grande do Norte, filling a gap in the known geographic distribution of the species between the states of Ceara and Pernambuco.

New record and geographic distribution map of Alexandresaurus camacan Rodrigues, Pellegrino, Dixo, Verdade, Pavan, Argôlo and Sites Jr., 2007 (Squamata: Gymnophthalmidae) in northeastern Brazil

We provide a new record of Alexandresaurus camacan for the state of Bahia and a distribution map for the species. Alexandresaurus was previously known from seven localities in the state of Bahia, all in the Atlantic Forest Domain. The new record is in the Serra da Jiboia, an enclave of Atlantic Forest in the Caatinga Domain.