Population genetic structure of the Antarctic ascidian Aplidium falklandicum from Scotia Arc and South Shetland Islands |
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Authors: | Milagros Demarchi Marina B Chiappero Marcos Tatián Ricardo Sahade |
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Institution: | 1. Ecología Marina, Facultad de Ciencias Exactas Físicas y Naturales, Universidad Nacional de Córdoba, Av. Vélez Sársfield 299, 5000, Córdoba, Argentina 2. Genética de Poblaciones y Evolución, Facultad de Ciencias Exactas Físicas y Naturales, Universidad Nacional de Córdoba, Av. Vélez Sársfield 299, 5000, Córdoba, Argentina 3. Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), Buenos Aires, Argentina
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Abstract: | In sessile marine organisms, gene flow between populations depends mainly on free-living reproductive stages (such as larvae
and gametes), and usually the strength of genetic structure is related to the time spent in the plankton and physical factors
as oceanographic conditions. In Antarctica, abyssal depths that surround the continent and the Polar Front are considered
strong barriers for benthic marine fauna, keeping the continent isolated from other shelves. The only available shallow water
habitats between South America and the Antarctic continent are those around the Scotia Arc Islands; there are no shallow water
habitats between the other southern continents and Antarctica. In this work, ISSRs-PCR markers were used to study the genetic
structure of populations of Aplidium falklandicum, a compound ascidian with short-lived lecitotrophic larvae. A highly significant genetic differentiation (ΦST = 0.405; P < 0.05) and a pattern of isolation by distance were found. A genetic landscape approach identified a discontinuity in genetic
diversity, coincident with the southernmost registered position of the Polar Front. For A. falklandicum, a species with presumably low capacity of long distance dispersal, the abyssal depths together with the large geographic
distances create a barrier for gene flow. |
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