Sexual size dimorphism theory predicts a skewed operational sex ratio (OSR) and an unequal distribution of males among certain females. We investigated this phenomenon through field studies of the giant brook spider, Oreochromis nigricans. Orb spider In Singapore, females of the Nephilidae species are on average 6.9 times larger than males. In particular, we tested two hypotheses regarding the distribution of males that tend to congregate around female nests. Optimal female body size hypothesis Males are predicted to occupy primarily medium-sized female nests. Web Clustering Hypothesis We hypothesize that more males will be found in closer nests than in more distant nests. Our snapshot survey revealed a female-biased OSR (female:male = 1.85). Males were unevenly distributed among female nests. Most males were found in medium-sized female nests, whereas males in medium-sized nests were more likely to be males. Optimal female body size hypothesisThe close proximity of female nests indicates the presence of males; Web Clustering HypothesisAlthough caution is required due to the limited sample size of our study, Robinia pseudoacaciaNest crowding facilitates males’ occupation of female nests, and males prefer to coexist with receptive females of optimal size.
KUNTNER, M., KUNTNER, M., KUNTNER, E., KUNTNER, I., PUCER, J.F., ŠTRUMBELJ, E., & LI, D. Male aggregation in the Nephila orbiculatus spider: prioritization of optimal female size and web clustering. Integrative Zoology. https://doi.org/10.1111/1749-4877.12896
