ABSTRACT
Exploited, understudied populations of the common octopus, Octopus vulgaris Cuvier, 1797, occur in the northeastern Atlantic (NEA) throughout Macaronesia, comprising the Azores, Madeira and Canaries, and also the Cabo Verde archipelago. This octopus species, found from the intertidal to shallow continental-shelf waters, is largely sedentary, and the subject of intense, frequently unregulated fishing effort. We infer connectivity among insular populations of this octopus. Mitochondrial control region and COX1 sequence datasets reveal two highly divergent haplogroups (α and ß) at similar frequencies, with opposing clinal distributions along the sampled latitudinal range. Haplogroups have different demographic and phylogeographic patterns, with origins related to the two last glacial maxima. FST values suggest a significant differentiation for most pairwise comparisons, including insular and continental samples, from the Galicia and Morocco coasts, with the exception of pairwise comparisons for samples from Madeira and the Canaries populations. Results indicate the existence of genetically differentiated octopus populations throughout the NEA. This emphasizes the importance of regulations by autonomous regional governments of the Azores, Madeira and the Canaries, for appropriate management of insular octopus stocks.
Subject(s)
Octopodiformes/classification , Phylogeography , Algorithms , Animals , Atlantic Ocean , Base Sequence , Bayes Theorem , DNA, Mitochondrial/genetics , Genetic Variation , Genetics, Population , Geography , Haplotypes/genetics , Octopodiformes/genetics , Probability , Regression AnalysisABSTRACT
Resumen Con el fin de establecer las épocas óptimas de explotación como posible recurso marisquero de dos especies de erizos de mar en Canarias, se estudió la evolución temporal del índice gonadal en diferentes años y localidades de Paracentrotus lividus (abril de 2006 a marzo de 2008 en la isla de Tenerife y en dos localidades: Las Galletas y La Jaca; abril de 2006 a enero de 2009 en la isla de Gran Canaria y en dos localidades: Ojos de Garza y Gando), y de Diadema africanum (de enero de 2010 a mayo de 2011 en la isla de Gran Canaria y en tres localidades: Risco Verde, Arguineguín y Agaete). En el caso de P. lividus, que se encuentra en el límite sur de su distribución, se constató la presencia de varios picos máximos anuales en el índice gonadal, probablemente relacionados con la temperatura. Estas épocas de mayor índice gonadal se correspondieron con los estados de maduración de las gónadas. La principal época de madurez coincidió con el otoño y comienzo del invierno (agosto, octubre y diciembre). Existió emisión de gametos esporádicos en el año según la localidad, en abril, en verano (junio, julio o agosto), otoño (septiembre u octubre) e invierno (diciembre, enero o febrero). Posiblemente esta situación tan dispar sea debido a la exposición al hidrodinamismo de la zona y a la presencia o no de abundante alimento. Para D. africanum se presentó el máximo índice en los meses de mayo-junio, con prácticamente pocas variaciones anuales en la localidad situada más al sur (Arguineguín). En conclusión, las dos especies de erizos serían complementarias como recursos marisqueros, ya que no se superponen sus periodos de máximos IG (época de captura) en el año.
Abstract There are three main species of regular sea urchins in the Canary Islands. To establish the optimal fishing seasons for two of them, we studied the evolution of the gonadal index in several years and locations, of Paracentrotus lividus (April 2006 to March 2008 on Tenerife island in two locations: Las Galletas and La Jaca and from April 2006 to January 2009 in Gran Canaria island in two locations: Ojos de Garza and Gando), and Diadema africanum (January 2010 to May 2011 on Gran Canaria island in three locations: Risco Verde, Arguineguin and Agaete). In the case of P. lividus, located on the southern edge of their distribution, the presence of several annual maximum gonadal indez peak was observed, probably related to the temperature. These times of gonadal index increases corresponded to the stages of maturation. The main period of maturity coincided with the fall and early winter (August, October and December). There was sporadic emissions of gametes depending on location, in April, during the summer (June, July or August), autumn (September or October) and winter (December, January or February). This fragmented situation is possibly due to exposure to the hydrodynamic area's and food abundance. The maximum presence of D. africanum occurred in the months of May to June, with virtually no variations throughout the year, in the southernmost locality (Arguineguin). In conclusion, the two species of sea urchins would be complementary shellfish resources, as their periods of maximum GI (Gonadal Index, capture time) do not overlap during the year. Rev. Biol. Trop. 63 (Suppl. 2): 251-260. Epub 2015 June 01.
Subject(s)
Animals , Sea Urchins/growth & development , Lytechinus/growth & development , Spain , CommerceABSTRACT
The Azorean barnacle, Megabalanus azoricus (Pilsbry, 1916), is a Macaronesian endemic whose obscure taxonomy and the unknown relationships among forms inhabiting isolated Northern Atlantic oceanic islands is investigated by means of molecular analysis herein. Mitochondrial data from the 16S rRNA and COX1 genes support its current species status, tropical ancestry, and the taxonomic homogeneity throughout its distribution range. In contrast, at the intraspecific level and based on control region sequences, we detected an overall low level of genetic diversity and three divergent lineages. The haplogroups α and γ were sampled in the Azores, Madeira, Canary, and Cabo Verde archipelagos; whereas haplogroup ß was absent from Cabo Verde. Consequently, population analysis suggested a differentiation of the Cabo Verde population with respect to the genetically homogenous northern archipelagos generated by current oceanographic barriers. Furthermore, haplogroup α, ß, and γ demographic expansions occurred during the interglacial periods MIS5 (130 Kya - thousands years ago -), MIS3 (60 Kya), and MIS7 (240 Kya), respectively. The evolutionary origin of these lineages is related to its survival in the stable southern refugia and its demographic expansion dynamics are associated with the glacial-interglacial cycles. This phylogeographic pattern suggests the occurrence of genetic discontinuity informative to the delimitation of an informally defined biogeographic entity, Macaronesia, and its generation by processes that delineate genetic diversity of marine taxa in this area.
