Ana Catalina Sánchez-Quirós

In adult spiders, leg lengths vary within and between species and is associated with functions in web construction, sensory activities, and prey capture. However, little is known about how leg proportions change during ontogeny. Here we investigate whether leg length relative to body size is maintained throughout development in three cobweb spiders ( Latrodectus geometricus , L. mactans , and Steatoda grossa ). Because spiderlings of these species build webs and capture prey from the first instar, we predicted proportional growth across instars. We also evaluate which model (linear, quadratic, or Gompertz) best describes femur and tibia growth, and estimated growth rates (first derivative) and accelerations (second derivative) for each sex and species. Legs were proportionally shorter in early than in later instars in L. geometricus and S. grossa , whereas proportions remained similar across development in L. mactans . Femur and tibia growth was best described by a quadratic model in both sexes of L. geometricus and L. mactans , and in males of S. grossa . In contrast, females of S. grossa followed a Gompertz trajectory; with high early growth rates that declined toward maturity. Despite these differences in trajectories, leg segments showed similar magnitudes of acceleration within species. Across the three theridiid species, females showed two distinct ontogenetic patterns–steady increases in growth rate (quadratic) or rapid early growth followed by deceleration (Gompertz)–whereas males consistently followed quadratic trajectories. Conserved acceleration among leg segments may reflect developmental canalization that preserves functional proportionality during growth.

Introduction: The Costa Rican southwestern region is considered one of the neotropical biodiversity hotspots. This geographically isolated forest embraces a rich diversity of moths and butterflies, which is still unknown for the most part. Objectives: (a) Describe and compare the diversity of moths and butterflies among different localities of the southwestern Costa Rican region, and (b) identify information gaps in this group of insects. Methods: Data for this study were collected in 12 different localities by parataxonomists and taxonomists for the national inventory of biodiversity led by INBio (National Biodiversity Institute) using different trap types, but relying mainly on light traps. We compared alpha and beta diversity of moths and butterflies among the six localities (Cortés, Piedras Blancas, Rancho Quemado, Agujas, Los Patos, Sirena) with more extensive sampling. Results: The dataset consisted of 78 747 specimens, of which 2 096 were identified only to the order level. The remaining 76 650 specimens were classified to the family level (n = 48 families), genus, species, or morphospecies. Species and morphospecies were distributed across 37 families. The alpha and beta diversity varied across localities for the 12 families of moths and butterflies that were present in the six localities selected. In general, Piedras Blancas, Rancho Quemado, and Sirena stand out as the most diverse localities. The richness of species varied among different families. For most families Agujas, Los Patos, and Sirena contained more species, but some other families showed a different pattern. Conclusion: Differences in the diversity of moths and butterflies over a northern-southern gradient likely correspond to species (individuals within species) adapted to different biotic (e.g., availability of host plants and food resources) and abiotic (e.g., microclimatic conditions associated to the complex topography of the region) conditions. Despite the large effort made by INBio in knowing and mapping the biodiversity of Costa Rica, and the economic and biological importance of the biodiversity, there are still a huge number of species to be known, named, and properly used.

Introduction: Understanding the factors underlying the interactions among closely related species continue to be an important issue in ecology and evolution. Warblers have been the group model for studying niche partitioning through interspecific competition, without considering other possible factors. A more recent approach includes species-specific morphologies as an important factor that correlates with habitat (or niche) partitioning. Objective: to compare the foraging strategies of five warbler species (Setophaga p. erithachorides, S. petechia, Protonotaria citrea, Parkesia noveboracensis, and Leothlypis peregrina) in a mangrove forest, and to compare the foraging strategies of S. p. erithachorides, the only resident warbler, between periods (presence vs. absence of migrants). Methods: We collected information on substrates and maneuvers used during foraging for the five warbler species during 39 sampling sessions. Each session consisted of recording information for 9 successive days every two weeks. Results: P. noveboracensis differed extensively from the other species in the foraging substrates and maneuvers. The other species formed a more compact group, but some differences in both, substrates and maneuvers, were detected between S. p. erithachorides and L. peregrina. Differences in forging strategies correlate with differences in the morphology among the five warbles species. The foraging strategy of S. p. erithachorides differed between periods. This warbler used the substrates similarly in both periods, but used other maneuvers or change their frequency when migrants are present. Conclusion: differences in the foraging strategy of five warblers can be attributed to a process of morphological and behavioral adaptation to an adaptive scape that includes differences in microhabitat, and biotic interactions (e.g., predation, prey availability) rather than exclusively to interspecific competition.