Genetic structure of the white croaker, Micropogonias furnieri Desmarest 1823 (Perciformes: Sciaenidae) along Uruguayan coasts: contrasting marine, estuarine, and lacustrine populations

Abstract

Micropogonias furnieri is widely distributed in the southwestern Atlantic Ocean. In Uruguay, Laguna de Rocha and Río de La Plata estuary have been reported as reproductive and nursery areas. In Laguna de Rocha, individuals reach maturity at smaller total length than their oceanic counterparts. It has been difficult to establish whether Laguna de Rocha represents a biologically distinct population or simply ecophenotypic variation. More generally, the possible presence of several distinct populations of white croakers in Uruguayan waters has been hypothesized, but limited data exist to substantiate them. A recent mitochondrial DNA analysis suggested divergence between the Río de La Plata and the Oceanic front populations. Using seven microsatellites loci, we studied the population structure of M. furnieri in the nursery areas suggested by the literature, as well as in three additional localities to test these hypotheses. The individuals of Laguna de Rocha showed a moderate genetic differentiation with respect to some of the other populations surveyed. Specimens of Montevideo showed the higher genetic distinctiveness. Given the apparent absence of geographical barriers, other factors may be responsible for the observed differentiation. The complex pattern of forces interacting in this system makes it difficult to disentangle the causes of the population structure found. The adaptation to local environmental conditions could be playing an important role in population differentiation, as well as the possible selective pressures imposed by fisheries. The results obtained in this work offer clues about the processes responsible for differentiation of fishes in estuarine and marine environments.

Variabilidad genética del robalo común Centropomus undecimalis (Perciformes: Centropomidae) en ambiente marino y ribereño interconectados

“…The estimated rate of migrants per generation (N m =18.7) prevents divergence by genetic drift (Slatkin, 1994;Freeland, 2005). D´Anatro et al (2011) came to the same conclusion with Micropogonias furnieri populations in Uruguay estuaries, where N m =2.9. Low population differentiation levels are common in fish species that breed in the ocean due to mechanisms that ensure constant gene flow among distant areas (Ward, 2000).…”

“…In contrast, physiologic tolerance mechanisms have been suggested as population divergence promoters in other euryhaline species. Although Micropogonias furnieri populations occur in different salinity habitats, they spawn in common coastal areas and juveniles apparently settle in their parents' original environment, therefore favoring genetic differentiation (D´Anatro et al, 2011). Estuarine habitat colonization by Odontesthes argentinensis has contributed to its adaptive divergence expressed by specific breeding requirements that favor ecotype formation and population differentiation (Beheregaray & Sunnucks, 2001).…”

“…The priority is to guarantee the sustainability of populations within their geographic range despite habitat alterations (Ward, 2000;Pritchard, Jones, & Cowley, 2007;Mehner, Pohlmann, Elkin, Monaghan, & Freyhof, 2009). Environmental differences found along the coastline play both an ecological and evolutionary role by favoring genetic differentiation (D´Anatro, Pereira, & Lessa, 2011) since the adaptive capacity of fish to withstand environmental changes determines the possibility of widening their distribution range and form new population units.In this study we analyzed if C. undecimalis individuals form a single genetic unit even though they are present in two connected, but dissimilar and distant environments. This is important since Snooks are exploited with different strategies and intensities in each geographical location.…”

Morphometric and meristic spatial differences and mixed groups of the whitemouth croaker (Micropogonias furnieri (Demearest, 1823)) during the spawning season: implications for management

“…The reproductive strategies of Micropogonias undulatus show a similar behaviour (Barbieri et al, 1994) that may facilitate gene flow (Lankford et al, 1999). Length of first maturity in females and males were similar for both groups, however, genetic results (Pereira et al, 2009;D'Anatro et al, 2011) showed differences in fish caught in the western and eastern areas. Spawning occurs during a southerly coastal migration during spring (Haimovici and Umpierre, 1996), and females can commence spawning in the northeast and spawn multiple times (Pravia et al, 1995;Macchi et al, 2003) during their southward migration (Norbis and Verocai, 2005), distributing maternal mtDNA clones over an extensive geographic range (Lankford et al, 1999).…”

Population genetic structure and body shape assessment of Pagrus pagrus (Linnaeus, 1758) (Perciformes: Sparidae) from the Buenos Aires coast of the Argentine Sea

“…On the other hand, significant morphological dissimilarities have been reported for P. pagrus along the Eastern Atlantic and the Mediterranean Sea as a direct consequence of environmental adaptation (Palma & Andrade, 2004). At a local scale, significant morphological differences, generally related to environmental variations in stripped weakfish Cynoscion guatucupa and white mouth croaker Micropogonias furnieri (Sabadin et al, 2010;D'Anatro et al, 2011) have also been informed on the Buenos Aires coast of the Argentine Sea.…”