The fiddler crab, Minuca pugnax, follows Bergmann's rule

Abstract

Bergmann's rule predicts that organisms at higher latitudes are larger than ones at lower latitudes. Here, we examine the body size pattern of the Atlantic marsh fiddler crab, Minuca pugnax (formerly Uca pugnax), from salt marshes on the east coast of the United States across 12 degrees of latitude. We found that M. pugnax followed Bergmann's rule and that, on average, crab carapace width increased by 0.5 mm per degree of latitude. Minuca pugnax body size also followed the temperature–size rule with body size inversely related to mean water temperature. Because an organism's size influences its impact on an ecosystem, and M. pugnax is an ecosystem engineer that affects marsh functioning, the larger crabs at higher latitudes may have greater per‐capita impacts on salt marshes than the smaller crabs at lower latitudes.

The impact of paleoclimatic changes on body size evolution in marine fishes

“…Studies of birds and mammals have found support for both rules ( 13 , 39 , 40 ). However, among ectotherms, findings have been mixed, with studies identifying support for Cope’s rule in arthropods ( 19 , 41 ) and reptiles ( 42 ); support for Bergmann’s rule in fishes ( 10 , 43 ), arthropods ( 8 , 11 , 19 ), reptiles ( 44 ), and amphibians ( 5 , 12 ); an inverse or no support for Cope’s rule in arthropods ( 45 ) and reptiles ( 23 , 46 ); and an inverse or no support for Bergmann’s rule in arthropods ( 47 ), reptiles ( 44 ), and amphibians ( 48 , 49 ). Bergmann’s rule, originally hypothesized for endothermic vertebrates ( 50 – 52 ), describes how larger endothermic species might conserve heat better in higher latitudes with cooler temperatures due to an increased surface area to volume ratio.…”

“…While Bergmann’s rule can apply at multiple evolutionary scales ( 9 ), from an interspecific viewpoint it can be defined as an ecogeographical trend where species’ body size varies as a negative function of temperature. Originally studied in mammals, this trend has now been identified in a range of animals such as crustaceans, amphibians, and ray-finned fishes ( 8 , 10 – 12 ). Various explanations have been proposed for Bergmann’s rule, from heat conservation in endotherms to oxygen availability in ectotherms ( 13 , 14 ).…”

Sediment selection: range-expanding fiddler crabs are better burrowers than their historic-range counterparts

“…S4). This does not mean size might not play a role in the wild, as PIE crabs tend to be larger than their southern counterparts (Johnson et al 2019). However, some other trait (either physical or behavioral) is generating the observed difference in burrowing ability of these 2 populations.…”

Estrutura populacional de Talitroides topitotum (Crustacea: Amphipoda: Talitridae) em Santa Maria, região central do Rio Grande do Sul, Brasil

“…Para as fêmeas ovígeras considerou-se a presença de ovos no marsúpio. A fim de avaliar a relação entre o tamanho corporal máximo de talitrídeos e a latitude em diferentes regiões, isto é, se a Regra de Bergmann (Johnson et al, 2019) age sobre esta espécie, foram coletados dados da literatura a partir de estudos sobre estrutura populacional de T. topitotum, juntamente com a latitude dos locais de amostragem. Os dados do presente trabalho também foram adicionados à análise e testou-se uma possível correlação entre tamanho e latitude.…”