Distinct pathophysiological mechanisms of Heterometrus laoticus and Lychas mucronatus scorpion venoms on cardiovascular and renal functions

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  Distinct pathophysiological mechanisms of Heterometrus laoticus and Lychas mucronatus scorpion venoms on cardiovascular and renal functions Abstract Background:    Heterometrus laoticus and Lychas mucronatus are widely distributed in Southeast Asia, yet their pathophysiological effects of both venoms remain poorly characterized due to low human fatality rates. This study compared their venom compositions and acute cardiovascular and renal effects. Methods:   Anesthetized male New Zealand White rabbits were monitored for blood pressure (BP), heart rate (HR), and renal clearance following intravenous administration of crude venom (0.5 mg/kg). Venom components were identified via LC-MS/MS, and hematological/biochemical parameters were assessed. Results:    H. laoticus venom induced a rapid, transient hypotension ( p < 0.05), followed by a mild, prolonged hypotensive phase (up to 120 min). Conversely, L. mucronatus venom elicited a biphasic response: ...

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 not affect SAM. Females were generally heavier than males in the second season but not in first, but mate assortments were random based on body mass in both seasons. Females showed a smaller carapace width in the first season and a larger one than males in the second season. Despite varying size differences between seasons, SAM remained homotypic based on carapace width across seasons and within the second season. Hence, homotypic SAM was consistent across different temporal scales. Male mate choice was not affected by female size. Unlike other species, temporal variation in the size of M. lemniscata spiders did not disrupt SAM, indicating that a consistent SAM can influence evolutionary changes in body size in this population.
Moura, R. R., Xavier, G. M., De Castro, V. C., Silva, W. D., Valentim, A. M., & Gonzaga, M. O. (2026). Homotypic assortative mating is consistent across temporal scales in the spider Mecynogea lemniscata (Araneidae). Zoologischer Anzeiger. https://doi.org/10.1016/j.jcz.2026.04.009