Biology subjects

Costa, G. C.

Publications and source records attributed to Costa, G. C..

3 recordsLinked to original sources

bioRxiv2022

Elevated human footprint on islands promotes both introduction and extinction probability of insular reptiles at opposite ends of geographic, evolutionary and ecological continua

Species ranges are changing in the Anthropocene, the ranges of introduced species are expanding, while extinction-prone species are contracting. Introductions and extinctions are both caused by how species respond to human impacts, but it is unknown why the ranges of some species expand and some contract. Here, we test that this opposite response of human impact is due to introduced and extinction-prone species falling at opposite ends of geographic, evolutionary, or ecological trait continua. We constructed a database of native range maps, traits, phylogenetic relationships, and the introduction and extinction-prone status of squamate reptiles with ranges native to the Western Hemisphere. Across >3,000 snake and lizard species (88% of known native squamates), 142 had been introduced elsewhere and 483 were extinction-prone (i.e., extinct, vulnerable, threatened). To explain variation in status, we first tested if the same human-impacted regions in the Americas contained the native ranges of species of either status. Second, we tested for phylogenetic signal in species status. Finally, we tested the explanatory power of multiple trait continua. The native ranges of introduced and extinction-prone reptiles were clustered in island regions with high human impact vs. mainland regions with lower human impact. Phylogenetic signal was weak for status, but introduced and extinction-prone species were clustered in different clades. All geographic and ecological traits that explained both statuses supported the opposite ends hypothesis. Introduced species had larger, edgier ranges, while extinction-prone species had smaller, simpler ranges. Introduced species were mostly herbivorous/omnivorous, while extinction-prone species were mostly carnivorous. Introduced species produced larger clutches, while extinction-prone species were smaller in body size. In the Anthropocene, the naive ranges of introduced and extinction-prone species are in the same human-impacted regions where trait continua, having opposite effects, determine whether species ranges expand or contract in the continuing face of global change.

ecology↗

bioRxiv2021

The trade-off between color and size in lizards' conspicuous tails

A tail of conspicuous coloration is hypothesized to be an advantageous trait for many species of lizards. Predator attacks would be directed to a non-vital, and autotomizable, body part, increasing the chance of survival. However, as body size increases it also increases the signaling area that could attract predators from greater distances, increasing the overall chance of predation. Here, we test the hypothesis that there is a trade-off between tail color and size, affecting predation probabilities. We used plasticine replicas of lizards to study the predation patterns of small and large lizards with red and blue tails. In a natural environment, we exposed six hundred replicas subjected to the attack of free-ranging predators. Large red-tailed models were attacked more quickly, and more intensely, by birds. Mammals and unidentified predators showed no preference for any size or colors. The attacks were not primarily directed to conspicuous tails when compared to the body or the head of our replicas. Our study suggests that red color signals in large lizards could enhance their detection by visually oriented predators (i.e., birds). The efficacy of conspicuous tails as a decoy may rely on associated behavioral displays, which are hard to test with static replicas. HighlightsO_LIThe roles of blue and red tails as decoys were not corroborated. C_LIO_LITail color and size interact while influencing predation rates. C_LIO_LILarger red-tailed lizards are more prone to be attacked by birds. C_LIO_LIThe benefit of having conspicuous tails appears to decrease as body size increases. C_LI

animal behavior and cognition↗

bioRxiv2019

Mechanistic macroecology: exploring the drivers of latitudinal variation in terrestrial body size in a General Ecosystem Model

Many mechanisms have been hypothesized to explain Bergmanns rule - the correlation of body size with latitude. However, it is not feasible to assess the contribution of hypothesised mechanisms by experimental manipulation or statistical correlation. Here, we evaluate two of the principal hypothesised mechanisms, related to thermoregulation and resource availability, using structured experiments in a mechanistic global ecosystem model. We simulated the broad structure of assemblages and ecosystems using the Madingley model, a mechanistic General Ecosystem Model (GEM). We compared emergent modelled biogeographic patterns in body mass to empirical patterns for mammals and birds. We then explored the relative contribution of thermoregulation and resource availability to body mass clines by manipulating the models environmental gradients. Madingley produces body size gradients that are in broad agreement with empirical estimates. Thermoregulation and resource availability were both important controls on body mass for endotherms, but only temperature for ectotherms. Our results suggest that seasonality explains animal body mass patterns through a complex set of mechanisms. Process-based GEMs generate broadly realistic biogeographic body mass patterns. Ecologists can use them in novel ways: to explore causality, or for generating and testing hypotheses for large-scale, emergent ecological patterns. At the same time, macroecological patterns are useful for evaluating mechanistic models. Iteratively developing GEMs, and evaluating them against macroecological patterns, could generate new insights into the complex causes of such patterns.

ecology↗