Genetic variation of a foundation rockweed species affects associated communities

A1 Journal article (refereed)


Internal Authors/Editors


Publication Details

List of Authors: Veijo Jormalainen, Maria Danelli, Karine Gagnon, Helmut Hillebrand, Eva Rothäusler, Juha-Pekka Salminen, Joakim Sjöroos
Publication year: 2017
Journal: Ecology
Journal acronym: Ecology
Volume number: 98
Issue number: 11
Start page: 2940
End page: 2951


Abstract










Genetic variation in a foundation species may affect the composition of associated communities as well as modify ecosystem function. While the ecological consequences of
genetic diversity of foundation species have been widely reported, the ability of individual
genotypes to support dissimilar communities has been documented only in forest ecosystems.
Here, for the first time in a marine ecosystem, we test whether the different genotypes of the
rockweed Fucus vesiculosus harbor distinct community phenotypes and whether the genetic
similarity of individual genotypes or their defensive compound content can explain the variation of the associated communities. We reared replicated genotypes in a common garden in the
sea and analyzed their associated communities of periphytic algae and invertebrates as well as
determined their contents of defense compounds, phlorotannins, and genetic distance based on
neutral molecular markers. The periphytic community was abundant in mid-summer and its
biovolume, diversity and community composition varied among the rockweed genotypes. The
diversity of the periphytic community decreased with its increasing biovolume. In autumn,
when grazers were abundant, periphytic community biomass was lower and less variable
among rockweed genotypes, indicating different relative importance of bottom-up regulation
through heritable variation of the foundation species and top-down regulation through grazing
intensity. Similarly, composition of the invertebrate community varied among the rockweed
genotypes. Although the genotype explained about 10–18% of the variation in associated com-
munities, the variation was explained neither by the genetic distance nor the phlorotannin con-
tent. Thus, neither neutral genetic markers nor a single phenotypic trait could provide a
mechanistic understanding of the genetic basis of community specificity. Therefore, a more
comprehensive mapping of quantitative trait variation is needed to understand the underlying
mechanisms. The community specificity implies that genetic variation within a foundation spe-
cies is crucial for the biodiversity and assembly of associated organisms and, thus, for the func-
tioning of associated communities. The result highlights the importance of ensuring the genetic
variation of foundation species as a conservation target.





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