Genetic and Morphological Differentiation of the Semiterrestrial CrabArmases angustipes(Brachyura: Sesarmidae) along the Brazilian Coast

Abstract

The genetic and morphometric population structures of the semiterrestrial crab Armases angustipes from along the Brazilian coast were examined. The influence of the Central South Equatorial Current on larval dispersal of A. angustipes also was evaluated. Six populations were sampled from estuarine areas in São Luis do Maranhão, Maranhão; Natal, Rio Grande do Norte; Maceió, Alagoas; Ilhéus, Bahia; Aracruz, Espírito Santo; and Guaratuba, Paraná. Patterns of genetic differentiation were assessed using DNA sequence data corresponding to parts of the mitochondrial cytochrome c oxidase subunit 1. Geometric morphometric techniques were used to evaluate morphological variation in shape and size of the carapace and right cheliped propodus. Our results revealed low genetic variability and lack of phylogeographic structure; geometric morphometrics showed statistically significant morphological differentiation and geographic structuring. Our data indicate the absence of possible barriers to gene flow for this mobile species, and no clear correlation of morphological or genetic variation with ocean currents and/or geographic distance. Our results also suggest that historical geological and climatological events and/or possible bottleneck effects influenced the current low genetic variability among the populations of A. angustipes.

Comparing the effect of larval dispersal strategies on morphological versus genetic differentiation in two neotropical fiddler crabs

“…Populations south and north of the CSEC split seem to exchange individuals between populations at least occasionally (shared haplotypes). A similar variation among populations within the hierarchical population division (north, split area, and south of CSEC split) was found for Armases angustipes (7.41%) (Marochi et al, 2017). The CSEC split reaches its southernmost position in July, increasing transport of water-bound plankton to the north, while its northernmost position is reached in November, increasing transport to the south (Rodrigues et al, 2007).…”

“…The same pattern was observed for Brazilian populations of Uca maracoani (Latreille, 1802) and Armases angustipes (Dana, 1852) (see Marochi et al, 2017;Wieman et al, 2014). Populations south and north of the CSEC split seem to exchange individuals between populations at least occasionally (shared haplotypes).…”

“…A lack or limitation of genetic structuring has also been observed in other South American brachyuran crab species Laurenzano et al, 2012Laurenzano et al, , 2013Marochi et al, 2017;Oliveira-Neto et al, 2007;Peres et al, 2020;Thurman et al, 2021;Wieman et al, 2014) and can possibly be attributed to a highly complex scenario. Physical factors (such as patterns of oceanographic circulation or air mass circulation, presence of islands, historical are important contributors influencing the genetic structure of organisms and should be taken into account, when conjecturing the degree of genetic differentiation of marine populations (Hedgecock, 1986;Laurenzano et al, 2013;McCartney et al, 2000;Palumbi, 2003;Poulin et al, 2002;Pringle & Wares, 2007;Riginos & Nachman, 2001;Sanford et al, 2006;Warner & Cowen, 2002;Weese et al, 2009).…”

“…On the other hand, the geometric morphometric tool is useful for quantifying a trait with evolutionary significance, by detecting changes in the outer shape and allowing a better understanding of species' evolution, and possibly ecological and behavioral traits. The combination of genetic and morphometric data has thus been used to understand the population biology and the microevolution of single species and the connectivity between estuarine faunas (Chaklader et al., 2016; Marochi et al., 2017).…”

Dimorfismo sexual e alometria ontogenética em Goyazana castelnaui (Crustacea, Brachyura)

“…De modo geral, técnicas de morfometria geométrica em crustáceos são utilizadas para identificar diferenças e variações significativas no formato e no tamanho de estruturas corpóreas, no intuito de entender questões evolutivas, ecológicas e relações intra-e interespecíficas (Rosemberg, 2002;Giri & Collins, 2004;Rufino et al, 2004;Giri & Loy, 2008;Tumelero & Fornel, 2014;Alencar et al, 2014;Diawol et al, 2015;Marochi et al, 2016;Marochi et al, 2017).…”