Homotypic assortative mating is consistent across temporal scales in the spider Mecynogea lemniscata (Araneidae)

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Homotypic assortative mating is consistent across temporal scales in the spider Mecynogea lemniscata (Araneidae) Abstract Identifying patterns of size-assortative mating (SAM) indicates the direction of genetic changes in a population. A reliable method for estimating it in a population is to measure mate assortments within and between breeding seasons¸ as well as describing size variation of males and females between temporal scales to avoid Simpson’s paradox. We assessed sexual size dimorphism, the effects of ontogeny, size differences within each sex, the consistency of SAM within and between seasons, and male mate choice in the spider  Mecynogea lemniscata . We collected mating pairs in a  Eucalyptus  plantation across two breeding seasons and in four periods of the second season. We measured body mass and carapace width of spiders. Males matured earlier than females and guarded subadult partners. Although adults were larger and heavier than subadults, ontogeny did no...

Diversification of Dolichothele mottai (Araneae: Theraphosidae), a Cerrado endemic tarantula

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Diversification of Dolichothele mottai (Araneae: Theraphosidae), a Cerrado endemic tarantula

Abstract

The Cerrado is a savannah domain occurring along the Central Brazilian Plateau and is a biodiversity hotspot. Two main hypotheses have been suggested in the study of lineage diversification in this domain. The first suggests that Pleistocene climatic fluctuations isolated populations of species in refugia, leading to their diversification. The second considers geomorphological or ecological processes in the Neogene as the main drivers of diversification in the Cerrado. Here, the first phylogeographical study of a Cerrado endemic spider, Dolichothele mottai, was conducted to test these diversification hypotheses, using genomic and mitochondrial data combined with tests of demographic models. Dolichothele mottai lineages diversified in the Mio-Pliocene, and a pattern of east–west genetic structuring along Central Cerrado plateaus was identified. Vicariance was the preferred model in demographic analysis, and geomorphological events in the Araguaia River Valley region during the Mio-Pliocene might have been relevant to the evolutionary history of this species. However, owing to demographic analyses, the influence of Pleistocene processes cannot be discarded as a possible hypothesis to explain lineage diversification in this species. Diversification patterns inferred here are concomitant with other Central Cerrado animal lineages, suggesting that processes in the Neogene influenced the diversification of phylogenetically distant groups.

Vespasiano, C. T., Serino-Silva, C., Machado Silveira, G. P., Rodrigues, F. S., Rameh-de-Albuquerque, L. C., Sant'anna, S. S., Grego, K. F., & Tanaka-Azevedo, A. M. (2025). Investigating the Influence of Hepatic Neoplasms on Bothrops Venom Biochemistry. Toxicon, 108561. https://doi.org/10.1016/j.toxicon.2025.108561