Brenda Mendoza-Almanza1, Raquel Muñiz-Salazar1, Zarko Altamirano-Gómez1, Sergio Larios-Castillo1, Fabiola Lafarga-de la Cruz2, Jose Miguel Sandoval-Gil1, Jose Antonio Zertuche-González1
1Universidad Autónoma de Baja California, Instituto de Investigaciones Oceanológicas, Ensenada 22860, Baja California, México
2 Department of Biological Oceanography, CICESE, Ensenada, Baja California, Mexico
Eisenia arborea is the kelp with the longest latitudinal distribution on the East-Pacific of North America (Vancouver, Canada to Baja California Sur, Mexico). Its broad distribution must be sustained by a high phenotypic plasticity and adaptation phenomena. However, few studies have linked the plasticity of some morphological traits (e.g. stipe length and hollowing, blade surface roughness) with oceanographic conditions (such hydrodynamics and nutrients availability), and even the genetic basis of its phylogeographic distribution still remained unknown. In this study, we collected E. arborea adult sporophytes from six different sites along 800 km of the peninsula of Baja California. We measured their morphological characteristics (number of blades, maximum blade length, blade width, stipe length and perimeter) in order to find correlations with oceanographic conditions from each site (temperature, salinity, and current velocity). The genetic differentiation among populations was also analyzed. Significant differences in morphological variables were observed among all sites. The PCA analysis explains 40% of the variance by the oceanographic variables. The dispersion graph clearly differentiates the sampled sites. Twelve microsatellites reported for Eisena cava were tested, but no significant genetic structure was observed. However, DNA sequencing based on ITS, rbcL, atp8 and trnW1 assigned all specimens to E. arborea. ITS and atp8 showed the highest number of haplotypes (5), while trnW1 showed 3, and rbcL 2 haplotypes. This study found moderate intraspecific genetic diversity and a shallow phylogeographic structure. The main structure showed 3 main clades along the Pacific Coast of Baja California.