Climatic and density-dependent drivers of population dynamics in a hazardous urban scorpion species over seven years

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  Climatic and density-dependent drivers of population dynamics in a hazardous urban scorpion species over seven years Abstract This link goes to a Portuguese section Tityus serrulatus Lutz & Mello (Scorpiones: Buthidae) is the most medically important scorpion in Brazil, responsible for a growing number of accidents in urban areas. Despite its relevance, the population dynamics of this species in anthropogenic habitats remain poorly understood, particularly regarding the influence of abiotic factors on its abundance and reproduction. We analysed long-term data (2006–2013) from T. serrulatus collected in an urban cemetery in the municipality of Americana, São Paulo State, Brazil. Using spatiotemporal mixed models, we evaluated the effects of temperature and humidity at the graves on the abundance of brooded and non-brooded individuals, as well as on the ratio between the two reproductive groups. A total of 21,489 individuals were recorded, including 463 brooded individuals. W...

Nephila spider male aggregation: preference for optimal female size and web clustering

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Nephila spider male aggregation: preference for optimal female size and web clustering

Abstract

Sexual size dimorphism theory predicts biased operational sex ratios (OSRs) and an uneven distribution of males among certain females. We studied this phenomenon through a field census of the giant wood spider Nephila pilipes (family Nephilidae) in Singapore, a species where females are, on average, 6.9 times larger than males. Specifically, we tested two hypotheses concerning male distribution, given their tendency to aggregate in certain female webs. The optimal female size hypothesis predicts that males would predominantly occupy webs of intermediate-sized females. The web clustering hypothesis posits that more males would be found in webs closer together compared to those farther apart. Our snapshot census revealed a female-biased OSR (females: males = 1.85) with an uneven distribution of males in female webs. Most males were found in webs of intermediate-sized females aligning with the optimal female size hypothesis. Proximity among female webs was indicative of male presence, lending support to the web clustering hypothesis. While our study's limited sample size warrants caution, we conclude that in N. pilipes, male occupation of female webs is facilitated by the clustering of webs, and males prefer to cohabit with optimally sized, receptive females.

KUNTNER, M., KUNTNER, M., KUNTNER, E., KUNTNER, I., PUCER, J. F., ŠTRUMBELJ, E., & LI, D. Nephila spider male aggregation: Preference for optimal female size and web clustering. Integrative Zoology. https://doi.org/10.1111/1749-4877.12896