ECOLOGICAL NICHE MODELS BY TITYUS SERRULATUS LUTZ & MELLO, 1922 AND TITYUS STIGMURUS (THORELL, 1876) (ARACHNIDA: SCORPIONES)

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  ECOLOGICAL NICHE MODELS BY TITYUS SERRULATUS LUTZ & MELLO, 1922 AND TITYUS STIGMURUS (THORELL, 1876) (ARACHNIDA: SCORPIONES) Summary Scorpions are venomous animals with high plasticity and can serve as models for biogeographical, natural history, and evolutionary studies. Ecological niche modeling can help in understanding essential characteristics of the geographic distribution of species, as well as allowing the prediction of future distribution patterns. Our objective was to model the ecological niche of the scorpion species *Tityus serrulatus * and *Tityus stigmurus* , as well as to identify the variables that influence their distribution in different biomes and their range limits in the Amazon, Caatinga, and Cerrado biomes. Data were obtained from 12 Brazilian arachnological collections. Bioclimatic variables were obtained from the WorldClim database, and niche modeling was implemented using the Maximum Entropy algorithm. The results showed that the Atlantic Forest bio...

Sexual dimorphism and functional allometry in scorpions: A comparative study from a neotropical species

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Sexual dimorphism and functional allometry in scorpions: A comparative study from a neotropical species

Abstract

Sexual dimorphism (SD), the divergence of secondary sexual traits between males and females within a species, can arise from diverse evolutionary forces, such as natural selection, mate choice, and intrasexual competition. Allometric scaling patterns of dimorphic traits are related to their functional roles and the different selective pressures that affect each sex. Generally, traits that threaten rivals involved in intrasexual competition tend to exhibit the highest allometric slopes. Conversely, non-sexual traits often display isometric scaling, while genitalia and traits in direct contact between the sexes during courtship and copulation typically show hypoallometry. A good approach to study patterns of SD and allometry is to complement interspecific studies with analyzes of case studies, where the functional aspect is known in detail. Here, we review the occurrence of SD and evaluation of allometry in the Order Scorpiones, allowing us to compare general trends in a broader comparative framework within the group. In addition, we examined SD and allometric slopes of multiple traits (including somatic traits used in sexual and non-sexual interactions, as well as genitalia) in adult individuals of the scorpion Timogenes elegans (Scorpiones, Bothriuridae). We found that at an interspecific level there was a variation in SD between species and morphological traits, with most traits showing a male-biased SD, except for the chelicerae, which were found to be wider in females. Regarding SD studies, we found relatively few reports of functional allometry showing differences in allometric patterns between species. The results in T. elegans follow some of the general patterns found in other scorpions. We found hypoallometry in genital traits and hyperallometry in the pedipalps of both sexes, with steeper allometric slopes observed for pedipalp height in males. These results suggest that genital traits are under stabilizing selective pressure, while pedipalps in both sexes may be under natural and sexual selective pressure. Understanding allometric patterns and their relationship to function in scorpions provides significant insights into the evolutionary pressures driving the divergence of morphological traits used in both sexual and non-sexual contexts.

Giménez Carbonari, J. J., Oviedo-Diego, M. A., Peretti, A. V., & Mattoni, C. I. (2024). Sexual dimorphism and functional allometry in scorpions: A comparative study from a neotropical species. Zoology, 126208. https://doi.org/10.1016/j.zool.2024.126208