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...

Interpopulational genetic diversity in the medically important scorpion Tityus obscurus (Scorpiones: Buthidae) from northeastern Brazilian Amazonia

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Interpopulational genetic diversity in the medically important scorpion Tityus obscurus (Scorpiones: Buthidae) from northeastern Brazilian Amazonia

ABSTRACT

Scorpion envenoming is considered a public health problem in Brazil. A recent study described a variation in the clinical outcome of envenoming by Tityus obscurus in two populations separated by 850 km in the northeastern Amazon region. Our aim was to evaluate whether such clinical and toxinological variations are associated with underlying differences in genetic diversity between these two T. obscurus populations. We obtained DNA from five individuals of each population, in the municipalities of Belém and Santarém, located east and west of the state of Pará, Brazil, respectively. Gene regions encoding mitochondrial DNA (mtDNA) markers cytochrome oxidase subunit I (COI) and ribosomal 16S RNA (16S) were amplified and sequenced. Phylogenetic analyses were performed using maximum likelihood (ML) and Bayesian inferences (BA) for both molecular data (COI and 16S). The sampled T. obscurus populations corresponded to two distinct mtDNA lineages (genetic distance COIK2 P = 0.08 to 0.13; 16SK2 P = 0.10 to 0.11) with no shared mutations between groups and well supported by ML and BA inferences. Based on the divergence values found between eastern and western populations (COI, 0.07 to 0.12; 16S, 0.10), our study confirms the genetic heterogeneity of T. obscurus populations within the state of Pará, which correlates with observed venom and clinical differences, and reinforces the need for mapping the distribution of haplotypes throughout the geographic range of T. obscurus, to aid in future epidemiological, toxinological, and evolutionary studies.


PARDAL, P. P. de O., COELHO, J. S., SILVA, J. M. da ., ALMEIDA, B. R. R., CHALKIDIS, H. M., BORGES, A., ISHIKAWA, E. A. Y., DINIZ, C. G., SANTOS-NETO, G. da C., & MELO, M. A. D. de .. (2023). Interpopulational genetic diversity in the medically important scorpion Tityus obscurus (Scorpiones: Buthidae) from northeastern Brazilian Amazonia. Acta Amazonica, 53(3), 215–222. https://doi.org/10.1590/1809-4392202202441