Genomic divergence was studied in 10 small insular populations of the endangered Balearic Islands lizard (Podarcis lilfordi) using double digest restriction-site associated DNA sequencing. The objectives were to establish levels of divergence among populations, investigate the impact of population size on genetic variability and to evaluate the role of different environmental factors on local adaptation. Analyses of 72,846 SNPs supported a highly differentiated genetic structure, being the populations with the lowest population size (Porros, Foradada and Esclatasang islets) the most divergent, indicative of greater genetic drift. Outlier tests identified ~ 2% of loci as candidates for selection. Genomic divergence-Enviroment Association analyses were performed using redundancy analyses based on SNPs putatively under selection, detecting predation and human pressure as the environmental variables with the greatest explanatory power. Geographical distributions of populations and environmental factors appear to be fundamental drivers of divergence. These results support the combined role of genetic drift and divergent selection in shaping the genetic structure of these endemic island lizard populations.

AimsTo characterize the genetic and morphological diversification of the endangered Balearic lizard Podarcis lilfordi and to assess the relevance of this diversity, and how it is described, to conservation measures.LocationThis study covers all the populations of the Balearic lizard, Podarcis lilfordi, present in its range of distribution at coastal islets of Menorca, Mallorca and Cabrera Archipelago.MethodsWe analysed genetic and morphological variation across the 43 known extant populations of the Balearic lizard, using mitochondrial and nuclear markers. We examined morphometric and scalation characters using, in some cases, phylogenetically independent contrasts. We also incorporated the study of dorsal coloration and dorsal colour pattern including the analysis of melanism in several populations.ResultsWe detected clear genetic divergence between Menorcan populations and populations from Mallorca and Cabrera, in both nuclear and mtDNA markers, but genetic divergence is relatively low among different insular populations within these groups. In contrast, morphological divergence was substantial both between Menorcan and remaining populations and within these groups. Morphological traits, such as dorsal coloration, body size and the number and size of scales, seemed to be linked with differences in climatic conditions between populations. In addition, some traits, as melanism, showed a strong phylogenetic signal.Main conclusionsThe morphological and genetic diversity of the Balearic lizard is incongruent with the subspecies described in the classical taxonomic literature. Moreover, current populations differ not only in some genetic and morphological features, but also in several ecological and ethological characteristics, in many cases unique to one population. Based on our results, we propose abandoning the use of subspecies to describe the extraordinary morphological diversity of the Balearic lizard and its replacement with the concept of evolutionary significant units (ESUs). ESUs are particularly suitable to describe and recognize such diversity and, especially, to ensure the continuity of the evolutionary process.

Fisheries management involves a broad and complex set of tasks that are necessary to prevent overfishing and to help the recovery of overfished stock. Monitoring fishing activities based on two main sources, landings data and scientific surveys, is a challenging task. Fisheries collection data is often limited, which compromises the accuracy of the results obtained. Therefore, several emerging applications of molecular methods have the potential to provide unique understanding of ecological processes in marine environments and to build stronger empirical underpinnings for the Ecosystem-Based Fisheries Management. Environmental DNA (eDNA) is a complex mixture of genetic material shed by those organisms that inhabit a given environment, whereby DNA is extracted from an environmental sample without accessing the target organism. eDNA studies can be categorized into two main approaches, i) eDNA metabarcoding or semi-targeted (community) approaches and ii) species-specific or targeted approaches (single). Although both categories are often discussed, they differ drastically in their methodology, interpretations and accuracy. Both approaches involve a series of steps that include eDNA capture, preservation, extraction and amplification. This detection will depend on the affinity to the targeted taxa sequences and completeness and accuracy of DNA reference collection databases. The eDNA method applied in marine environments are probably the most challenging aquatic environments for applying this technique. This is because of the extreme relationship between water-volume to biomass, dynamics and the physical and chemical properties of seawater that affect dispersion, dilution and preservation. Here, we review the present application of this novel method in fishery assessment in marine environments. To date, many studies suggest that this method offers the potential to revolutionize fisheries monitoring, which will contribute to improving the range of tasks involved in fisheries management. The compelling conclusion is that the methodological steps including in eDNA surveys should be standardized and that research efforts should focus on developing appropriately validated tests to address environmental and sampling factors that may affect eDNA detection in marine environments in order to draw reliable conclusions. This bioassessment tool can assist fisheries professionals in achieve their research, management, and conservation objectives, but not as a replacement for time-proven assessment methods.

Morphological and genetic studies spanning the last 25 years have attempted to clarify relationships both within and between lineages of the major lacertid lizard genus Podarcis from the Iberian Peninsula and North Africa. These studies reported that all Podarcis that inhabit this region, with the exception of Podarcis muralis (Laurenti, 1768), form a monophyletic group (Arnold, Arribas, & Carranza, 2007; Carranza, Arnold, & Amat, 2004) that is generally referred to as the Podarcis hispanicus (Steindachner, 1870) species complex. Currently, seven genetically distinct lineages within this complex have been raised to species level:

Perkinsus mediterraneus, a protozoan parasite that can cause perkinsosis (marine mollusc disease), was first detected in oysters Ostrea edulis from Mahon (Minorca, Balearic Islands, Spain) in 2004. Several years later it was also found in Andratx Harbour (Majorca, Balearic Islands) and in the Gulf of Manfredonia (Adriatic coast of Italy) in oyster populations. Since 2007, Perkinsus surveys have been conducted in different localities and shellfish species in the Balearic Archipelago. In the present work, we found P. mediterraneus in the Balearic Islands infecting oyster and other shellfish species. We describe infection with P. mediterraneus for the first time in Arca noae and Mimachlamys varia. The detection was carried out using Ray's fluid thioglycolate medium (RFTM), histology and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) methodologies. The internal transcribed spacer (ITS) region (including ITS1, 5.8S and ITS2) of P. mediterraneus ribosomal DNA was sequenced from infected bivalve gills (or from the body in Chamelea gallina) from Balearic Archipelago localities. Twelve haplotypes with a strong genetic similarity between them (97-100%) were observed in our samples. These data were completed with 12 more haplotypes from GenBank sequences. The phylogenetic relationship between Balearic P. mediterraneus haplotypes found in this study, those previously obtained in Mahon Harbour, and the Perkinsus spp. sequences available in GenBank clearly grouped the different Perkinsus spp. in distinct clades supported by strong bootstrap values. Moreover, these analyses detected different P. mediterraneus groups in O. edulis from Minorca Island. No abnormal mortalities or decline in populations were detected during the survey, except for C. gallina, which is also affected by Marteilia refringens.