Abstract
Alexandrium catenella is the main species that form harmful algae blooms (HABs) in southern Chile. Since its first record in 1972 in the Magallanes region this species apparently has increased its range distribution from south to north. In this study, we investigate the influence of the range expansions distribution on the A. catenella populations genetic diversity and structure. This was achieved by isolating 33 clones from different localities along the Magallanes and Aysén region which were genetically characterized with Amplified Fragment Length Polymorphism (AFLPs) molecular markers. Results showed a latitudinal genetic diversity gradient from the south to north populations. Inter-populations genetic divergences were low but significant between both geographically close and distant populations. Results indicated that the genetic diversity differentiation could be generated by a founder effect, which is expected in populations that have expanded their distribution range. On the other hand, low levels of genetic divergences between distant populations seems point out that high gene flow occurs along coast of the Pacific Ocean, but also, seems hints the connectivity route between the Magallanes and Aysén populations i.e., the vegetative cells dispersion among populations, would occur through coastal Pacific coast and Boca del Guafo. Finally, the high values of multilocus linkage disequilibrium found between closer population of Aysén indicates that divergence could be influenced along with the reproductive dynamic of the vegetative cells.
Highlights
In southern Chile, Alexandrium catenella (Whedon and Kofoid) Balech is the main species forming harmful algae blooms (HABs), affecting ecosystems and human health (Varela et al 2012, Paredes et al 2019)
After evaluation and filtering of the Amplified Fragment Length Polymorphism (AFLPs) raw data 770 loci were retained for genetic analysis
Significant differences in the genetic diversity were found among populations (GLMM, ANOVA Chi square= 45.945, P < 0.01), being the south Aysén population the only differentiated
Summary
In southern Chile, Alexandrium catenella (Whedon and Kofoid) Balech is the main species forming harmful algae blooms (HABs), affecting ecosystems and human health (Varela et al 2012, Paredes et al 2019) This species has been monitored for the last four decades throughout the Patagonian fjords (Guzmán et al 2002, Seguel et al 2005, Alves-de-Souza et al 2008, Mardones et al 2010), showing an apparent northward geographic expansion (Guzmán et al 2002, Molinet et al 2003, Mardones et al 2010, Varela et al 2012). An apparent expansion in the distribution range of Alexandrium species has been described along the Atlantic coast of South America (Persich et al 2006) and in some zones of the northern hemisphere (Vila et al 2001, Penna et al 2005, Masseret et al 2009, Anderson et al 2012)
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