Environmental variables, habitat discontinuity and life history shaping the genetic structure of Pomatoschistus marmoratus

Abstract

Coastal lagoons are semi-isolated ecosystems exposed to wide fluctuations of environmental conditions and showing habitat fragmentation. These features may play an important role in separating species into different populations, even at small spatial scales. In this study, we evaluate the concordance between mitochondrial (previous published data) and nuclear data analyzing the genetic variability of Pomatoschistus marmoratus in five localities, inside and outside the Mar Menor coastal lagoon (SE Spain) using eight microsatellites. High genetic diversity and similar levels of allele richness were observed across all loci and localities, although significant genic and genotypic differentiation was found between populations inside and outside the lagoon. In contrast to the F ST values obtained from previous mitochondrial DNA analyses (control region), the microsatellite data exhibited significant differentiation among samples inside the Mar Menor and between lagoonal and marine samples. This pattern was corroborated using Cavalli-Sforza genetic distances.The habitat fragmentation inside the coastal lagoon and among lagoon and marine localities could be acting as a barrier to gene flow and contributing to the observed genetic structure. Our results from generalized additive models point a significant link between extreme lagoonal environmental conditions (mainly maximum salinity) and P. marmoratus genetic composition. Thereby, these environmental features could be also acting on genetic structure of coastal lagoon populations of P. marmoratus favoring their genetic divergence. The mating strategy of P. marmoratus could be also influencing our results obtained from mitochondrial and nuclear DNA. Therefore, a special consideration must be done in the selection of the DNA markers depending on the reproductive strategy of the species.

Genetic diversity across geographical scales in marine coastal ecosystems: Holothuria arguinensis a model species

“…A recent work focused on H. polii showed higher values of genetic diversity and presence of Nowadays, there are two alternative hypotheses explaining the genetic diversity patterns in transitional ecosystems. The first hypothesis suggests that, adaptation of the organisms to high variable environments occurs through high genetic variation which facilitates the occurrence of different allele variants to adapt to extreme environmental conditions (González-Wangüemert et al, 2006Vergara-Chen et al, 2010a, 2010bGonzález-Wangüemert and Pérez-Ruzafa, 2012;Vergara-Chen et al, 2013;González-Wangüemert and Vergara-Chen, 2014). The second one holds that in fluctuating conditions, adaptation involves the selection of one particular genotype which presents flexibility in responding to environmental variation allowing survival and ensuing in low genetic variation (Abbiati and Maltagliati, 1992;Vasileiadou et al, 2012;González-Wangüemert et al, 2014a).…”

“…Coastal lagoons are also characterized by their exposure to wide oscillations of environmental variables such as salinity, temperature, pH, oxygen, and organic matter (Bamber, 2010). These characteristics coupled to geographical and eco-physiological discontinuities, might instigate intraspecific variability and may enhance the evolutionary potential of brackish water environments (González-Wangüemert and Pérez-Ruzafa, 2012;González-Wangüemert and Vergara-Chen, 2014;Vergara-Chen et al, 2013. Being this a general pattern, some exceptions in which the survival to stressed environment is not necessarily linked with a higher genetic diversity of the population can be also found (e.g.…”

“…Recent studies have tackled the role of the coastal lagoons and estuaries as inducers of genetic differentiation (González-Wangüemert and Pérez-Ruzafa, 2012;González-Wangüemert and Vergara-Chen, 2014;González-Wangüemert et al, 2006González-Wangüemert et al, 2014a;Vergara-Chen et al, 2010a, 2010b, 2013. The existence of these genetic differences between lagoon and marine populations could be the result of the selection acting in the lagoon organisms which could favor some vital adaptations for surviving in these heterogeneous environments González-Wangüemert et al, 2006;Vergara-Chen et al, 2010a).…”

“…The emergence of these local adaptations could lead to higher levels of genetic heterogeneity into the lagoons (Vergara-Chen et al, 2013. The lagoon role as nursery and recruitment areas could be also contributing for the genetic differences and higher genetic diversity: lagoons provide optimal habitats to larvae and recruits from diverse geographical origins, allowing the mixture of different genetic pools and therefore increasing its genetic diversity (González-Wangüemert and Pérez-Ruzafa, 2012;González-Wangüemert and Vergara-Chen, 2014). Obviously the genetic structure of the organisms inhabiting these ecosystems, will be also influenced by the life history traits of the species (e.g.…”

Effects of fishery protection on biometry and genetic structure of two target sea cucumber species from the Mediterranean Sea

“…The high number of exclusive haplotypes showed in Kusadasi area may increase their fitness under unusual conditions (Ryman et al, 1995;Pérez-Ruzafa et al, 2006;Vergara-Chen et al, 2010;González-Wangüemert & Vergara-Chen, 2014). That genetic diversity could provide the raw material for the maintenance of the diversity longer evolutionary time-scales and may also confer the basis for adaptation to environmental change (Sanford & Kelly, 2011;González-Wangüemert & Vergara-Chen, 2014).…”