Effects of temperature on reproductive timing and hatching success in a tropical fiddler crab

Abstract

The timing of reproduction is critical to reproductive success in many animal species. Parents that can perceive and respond to environmental cues and time the hatching/birth of their offspring to optimal environmental conditions show higher reproductive success. Intertidal ectotherms are under particularly strong selection because larval development rates are temperature-dependent, and larvae must hatch during the highest spring tides to avoid high levels of inshore predation. Here we investigate whether female fiddler crabs, Austruca mjoebergi, can mitigate the effects of high temperatures by adjusting the timing of reproductive events and/or by behavioural compensation. We experimentally manipulated incubation temperatures between 30 and 36 °C, based on natural and predicted temperature conditions, and found that hatching success decreased linearly with increasing temperatures. However, temperature had no effect on the timing of fertilization or hatching, suggesting that larval development rate was not temperature-dependent. Across the tested temperatures, females did not adjust egg size, the amount of yolk in each egg, larvae size or clutch size. In conclusion, high temperatures prevented clutches from reaching the hatching stage, but within the range of temperatures that facilitated hatching, there was no evidence of behavioural compensation and no discernible effect of temperature on reproductive timing.

Why sex matters in phenological research

“…For example, it is intriguing to ask to what extent the timing of juvenile emergence is influenced by the environment (e.g. in temperate insects), and whether parental control can mitigate the negative impact of climate change that triggers juvenile emergence at maladaptive timing (Chou et al 2019). Population‐ and community‐level data can be used to validate theoretical predictions and model calibration.…”

Temporal variations in the air, soil, and fiddler crab (Austruca perplexa) burrow temperatures in southern Thailand

“…Among these environmental constraints, temperature is the most important since it affects their behaviour, physiology, growth, and reproduction (Weinstein 1998;Ruscoe et al 2004;Resgalla et al 2007;Allen et al 2012). In the case of fiddler crabs, very high or very low temperature affects their metabolic rates, heart rates, haemolymph osmolality, muscle hydration, ovarian development, and egg hatching success (Vernberg and Vernberg 1966;Eshky et al 1995;Matsumasa and Murai 2005;Colpo and López-Greco 2017;Principe et al 2018;Chou et al 2019). They have developed several physiological, morphological, and behavioural adaptations for dealing with the very high or low temperature (Eshky et al 1995;Thurman 1998;Yoder et al 2005;Levinton et al 2015;da Silva Vianna et al 2020).…”