How Female Choice and Male Behavior Affect Courtship and Mating in Spiders

Jenn Hoskins
28th June, 2024

How Female Choice and Male Behavior Affect Courtship and Mating in Spiders

Image Source: Natural Science News, 2024

Key Findings

  • The study, conducted at the University of Toronto, examined male courtship behaviors in five widow spider species
  • Males from species with high rates of sexual cannibalism invested more in courtship, as they are likely to mate only once
  • Increased male courtship investment was linked to greater female control over mating outcomes, with females preferring longer courtships
Understanding the dynamics of male courtship investment in widow spiders can provide insights into broader evolutionary processes. A recent study conducted by researchers at the University of Toronto[1] investigated how male courtship behaviors in five widow spider species (genus Latrodectus) evolve in response to mating opportunities and female control during mating interactions. This study aimed to test whether males invest more in courtship when future mating opportunities are limited due to high rates of sexual cannibalism or when females exert greater control over mating outcomes. Sexual conflict, which arises from differences in the evolutionary interests of males and females, can lead to sexually antagonistic coevolution (SAC)[2]. Such conflict often influences traits related to courtship, mating, and fertilization. In this context, male courtship investment becomes a critical trait that can evolve in response to these conflicts. The study by the University of Toronto researchers builds on this understanding by examining how male courtship investment varies across species with different levels of sexual cannibalism and female control. The researchers selected five widow spider species with varying degrees of sexual cannibalism: L. geometricus, L. hasselti, L. mirabilis (high cannibalism rates, monogyny), and L. mactans, L. hesperus (rare cannibalism). They hypothesized that males from species with high cannibalism rates would invest more in courtship since they are likely to mate only once. In contrast, males from species with rare cannibalism would reserve energy for future mating opportunities. The study also explored whether increased male courtship investment correlates with increased female control over mating outcomes, which could be indicated by the frequency of copulations and the timing of sexual cannibalism. The researchers conducted their experiments under controlled laboratory conditions, measuring courtship duration, frequency of copulations, and the timing of sexual cannibalism. They also assessed the degree of female-biased size dimorphism, which is expected to correlate with the energetic cost of rebuffing male mating attempts. The findings revealed that males from species with high cannibalism rates indeed invested more in courtship, as predicted. These males exhibited longer courtship durations, suggesting that they allocate more energy to a single mating opportunity. Furthermore, the study found that increased male courtship investment was associated with greater female control over mating outcomes. In species where females had more control, indicated by their ability to choose longer courtships, males exhibited higher courtship durations. This aligns with the idea that males adjust their investment based on the likelihood of successful mating, influenced by female preferences and behaviors. These findings are consistent with previous research on metabolic efficiency and courtship in spiders. For example, a study on the Australian redback spider, L. hasselti, demonstrated that intermediate-mass males were the most metabolically efficient courters, producing high-energy vibrational signals necessary for prolonged courtship[3]. This efficiency allows males to maximize their courtship efforts without depleting their finite energy reserves, which is crucial in species where males invest heavily in a single mating opportunity. Additionally, the study's results contribute to our understanding of sexual size dimorphism (SSD) in spiders. Extreme female-biased SSD is common in certain spider lineages and is often associated with sexual cannibalism and other extreme sexual phenotypes[4]. The equilibrium model proposed for SSD suggests that clade- and context-specific drivers influence gender size variation. The current study's findings support this model by showing that male courtship investment and female control are context-specific factors that shape the evolution of these traits in widow spiders. In conclusion, the University of Toronto study provides valuable insights into how male courtship investment evolves in response to mating opportunities and female control in widow spiders. By examining the interplay between sexual cannibalism, courtship duration, and female preferences, the researchers have expanded our understanding of sexually antagonistic coevolution and the factors driving the evolution of mating behaviors in spiders. These findings highlight the importance of considering both male and female perspectives in the study of sexual selection and conflict.

GeneticsAnimal ScienceEvolution

References

Main Study

1) Does female control and male mating system predict courtship investment and mating outcomes? A comparative study in five widow spider species (genus Latrodectus) tested under similar laboratory conditions

Published 27th June, 2024

https://doi.org/10.1186/s12862-024-02272-9

Related Studies

2) Evolutionary conflicts of interest between males and females.

Journal: Current biology : CB, Issue: Vol 16, Issue 17, Sep 2006

3) Metabolic efficiency in courtship favors males with intermediate mass in the Australian redback spider, Latrodectus hasselti.

https://doi.org/10.1016/j.jinsphys.2014.11.004

4) Sexual Size Dimorphism: Evolution and Perils of Extreme Phenotypes in Spiders.

https://doi.org/10.1146/annurev-ento-011019-025032


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