Size-at-age or structure shift: Which hypothesis explains smaller body size of the fiddler crab Leptuca uruguayensis in northern populations?

Sharing is living: The role of habitat heterogeneity in the coexistence of closely related species

“…Higher temperatures cause L. uruguayensis to increase metabolic costs in comparison to L. leptodactyla (Vianna et al, 2020 ), as well as temperatures about 29°C affect the growth, reproduction, and survival of L. uruguayensis (De Grande et al, 2021 ). The thermal stress is also related to the species' latitudinal distribution pattern, since L. uruguayensis habits subtropical and temperate along the South American coast limited by higher temperatures in lower latitudes (De Grande et al, 2021 ), while L. leptodactyla habits neo‐tropical shores of the western Atlantic (Thurman et al, 2013 ), probably with the distribution limited by the lower temperatures in higher latitudes. Therefore, independently of sympatric interactions, physiological stressors are crucial in the spatial distribution of fiddler crabs (Nobbs & Blamires, 2017 ), not only on a latitudinal scale but also regarding differences in microhabitats.…”

“…The last experiment tested males' crab critical thermal maximum (CT max ) to evaluate whether L. uruguayensis are more sensitive to heat than L. leptodactyla . The experiment consisted of raising the water temperature from 25°C to 50°C till the crabs' motor coordination is lost (De Grande et al, 2021 ). The CT max was calculated as the average temperature at which individuals were not able to recover their position (Allen et al, 2012 ).…”

“…Our findings are following what is predicted for these species. Higher temperatures cause L. uruguayensis to increase metabolic costs in comparison to L. leptodactyla(Vianna et al, 2020), as well as temperatures about 29°C affect the growth, reproduction, and survival of L. uruguayensis(De Grande et al, 2021). The thermal stress is also related to the species' latitudinal distribution pattern, since L. uruguayensis habits subtropical and temperate along the South American coast limited by higher temperatures in lower latitudes(De Grande et al, 2021), while L. leptodactyla habits neo-tropical shores of the western Atlantic(Thurman et al, 2013),…”

Plasticity of growth rates and sizes at sexual maturity in different populations of the fiddler crab Minuca vocator (Herbst, 1804) within the same latitudinal range

“…At colder temperatures, the intermolt period is longer, leading to a larger increase in size at each molt. Therefore, decapods from colder environments (high latitudes) would reach sexual maturity at larger sizes than conspecifics from warmer environments (low latitudes) (Landers et al 2002, Kuhn & Darnell 2019, Mullowney & Baker 2020, De Grande et al 2021. Several species of decapods show this pattern of larger maturity sizes at higher latitudes (Hines 1989, Le Bris et al 2017, Olson et al 2018, Johnson et al 2019, Martínez-Rivera et al 2020).…”