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: ...

What about male quality? A model to predict male investment in a single female

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What about male quality? A model to predict male investment in a single female

Abstract

Monogyny—where a male invests all his reproductive effort in a single female—is a rare and poorly understood mating system. It contradicts conventional sex roles, in which males typically seek multiple mates while females may mate repeatedly. Previous theoretical work has shown that monogyny is most likely to evolve under male-biased sex ratios, as often occurs in species with extreme female-biased sexual size dimorphism (eSSD). While previous models mainly considered the species level, potential individual strategies have received little attention. Here we used a game theory approach, considering the interplay between male and female decisions, to address how variation in male quality (e.g., size or body condition) affects the payoff of a monogynous strategy. The model is based on the biology of widow spiders, where males exhibit extreme mating investment including prolonged courtship, mate guarding, genital damage and even self-sacrifice, but can be relevant to other species with eSSD. The results of the model confirm previous predictions and point to a novel, testable, and somewhat surprising prediction: unless females are extremely rare relative to males, and/or male survival prospects are very slim, the highest quality males would avoid extreme investment and rather set out to look for additional females to mate with. This is because high-quality males face a lower risk that the female will not use their sperm, and they are also likely to be accepted by subsequent (even already mated) females. Future studies could address this hypothesis experimentally by comparing the tendency of males of varying qualities to invest in a current mate under different demographic and ecological conditions.

Heifetz, A., Lubin, Y., Schneider, J., & Segoli, M. What about male quality? A model to predict male investment in a single female. Journal of Evolutionary Biology. https://doi.org/10.1093/jeb/voag029