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On the advantage of sharing a holdfast: effects of density and occurrence of kin aggregation in the kelp Lessonia berteroana
Author(s) -
Segovia Nicolás I.,
Vásquez Julio A.,
Faugeron Sylvain,
Haye Pilar A.
Publication year - 2015
Publication title -
marine ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.668
H-Index - 58
eISSN - 1439-0485
pISSN - 0173-9565
DOI - 10.1111/maec.12206
Subject(s) - holdfast , kelp , biology , density dependence , genetic structure , genetic variation , genetic diversity , ecology , evolutionary biology , population , genetics , gene , demography , sociology
We investigated the density‐dependent and genetic relatedness that regulate the occurrence of inter‐individual (genet) fusion forming plurigenotypic organisms in the brown alga L essonia berteroana . Recruitment generally occurs at high densities in the inter‐tidal, allowing contact of neighbouring holdfasts as they grow and expand on the substrate. Algal density, by contrast, is regulated by the effects of herbivory and wave impact, which often lead to low holdfast density. Herein, we investigated whether the occurrence of plurigenotypic organisms and their genotypic composition (number of genotypes per plurigenotypic organism) are density dependent and affected by kin selection in the inter‐tidal kelp L . berteroana . Four microsatellite loci were used to analyse DNA from 260 samples obtained from shared and non‐shared holdfasts, at two sites with high and two site with low holdfast density. Analyses showed that fusions forming plurigenotypic organisms are extremely common. Interestingly, the frequency of fusions was higher in low‐density sites, in which 100% of the plants had at least two genotypes and the average was 3.5. In high‐density sites, 62% of plants were plurigenotypic, with an average of 2.8 genotypes per plant. Additionally, we found that genotypes that shared a holdfast had a significantly higher genetic relatedness than the average in the population, compatible with a kin structure. Density dependence and kin structure suggest that the occurrence of plurigenotypic organisms is linked to environmental quality, and that kin or multilevel selection may be favouring the fusion of genetically related genets.