High genetic differentiation of Aegla longirostri (Crustacea, Decapoda, Anomura) populations in southern Brazil revealed by multi-loci microsatellite analysis

Abstract

ABSTRACT. Species with a broad distribution rarely have the same genetic make-up throughout their entire range. In some cases, they may constitute a cryptic complex consisting of a few species, each with a narrow distribution, instead of a single-, widely distributed species. These differences can have profound impacts for biodiversity conservation planning. The genetic differentiation of four populations of Aegla longirostri, a freshwater crab found in two geographically isolated basins in Rio Grande do Sul State, Brazil, was investigated by analyzing pentanucleotide multi-loci microsatellites in a heteroduplex assay. Although no morphological differences were evident, we found significant genetic differentiation among the four populations, based on F ST values and clustering analysis. This high level of differentiation may be indicative of cryptic species in these populations. If this hypothesis is correct, then the species occurring in the Ibicuí-Mirim ©FUNPEC-RP www.funpecrp.com.br Genetics and Molecular Research 10 (4): 4133-4146 (2011) M.L. River, at the southern limit of the Atlantic Rain Forest, would be under threat, considering its very restricted distribution.

Intraspecific variation inAegla longirostri(Crustacea: Decapoda: Anomura) revealed by geometric morphometrics: evidence for ongoing speciation?

“…These populations were the same as those analysed by Bartholomei‐Santos et al . (), except the Jacuí River and Felisberto/Caemborá streams. All individuals of A. longirostri were identified using the diagnostic characters for the species, as described by Bond‐Buckup & Buckup ().…”

“…Subsequently, Bartholomei‐Santos, Roratto & Santos () investigated the genetic structure of four populations of A. longirostri in Rio Grande do Sul State, Brazil. One of these populations was located in a different basin, being geographically isolated from the others.…”

“…The description of patterns of variation in genetic and morphological characters within and among populations is fundamental for defining boundaries of independent evolutionary units in nature (Fernandes et al ., ). Considering the high genetic differentiation previously found between A. longirostri populations (Bartholomei‐Santos et al ., ), and the possible existence of cryptic species within this group, our objective was to analyse A. longirostri populations using a geometric morphometric approach, to better elucidate the group's systematics using complementary methods to genetics.…”

Clinal variation in carapace shape in the South American freshwater crab,Aegla uruguayana(Anomura: Aeglidae)

“…Current knowledge regarding A. uruguayana has been provided by research of biometric characteristics of the genus (Vaz‐Ferreira, Gray & Vaz‐Ferreira, ; Ringuelet, , ; Bond‐Buckup & Buckup, ); moreover, molecular information on the genus has also been characterized (D'Amato & Corach, , b; Pérez‐Losada et al ., ; Bitencourt, ; Bartholomei‐Santos, Roratto & Santos, ; Giri et al ., ). Information about the shape of the carapace has been found to aid in the differentiation of males from females (Giri & Collins, ) and the relationship between the shape of the coxa and the dorsoventral shape of the fifth pereiopod has been used to identify whether gonadal maturation has occurred (Collins, Giri & Williner, ).…”

Morphometric variation in allopatric populations of Aegla platensis (Crustacea: Decapoda: Anomura): possible evidence for cryptic speciation

“…The disadvantages resulting from the mating of genetically differentiated populations, such as offspring infertility and sterility, can reinforce the isolation between populations, indirectly leading to phenotypic differentiation (Fornel et al 2010). The presence of gene flow could be a mechanism capable of preventing this differentiation; however, the migration or dispersal rate between certain allopatric populations can be very low or even null nowadays (Rieseberg and Burke 2001; Bartholomei-Santos et al 2011). The lack of gene flow, combined with genetic divergence, can lead to reproductive isolation, which is a fundamental step toward the emergence of new species (Schemske 2000).…”