Genetic erosion reduces biomass temporal stability in wild fish populations

Abstract

28Theory predicts that biodiversity is causally linked to key ecological functions such as biomass 29 productivity, and that loss in functional traits both among-and within-species can reduce the efficiency of 30 ecosystem functions. There has been ample empirical and experimental demonstration that species loss 31 indeed reduces the efficiency of ecosystem functions, with tremendous impacts on services provided by 32 biodiversity. Nonetheless, and despite the fact that within-species diversity is strongly altered by human 33 activities, there have been little attempts to empirically test (i) whether intraspecific genetic diversity 34 actually promotes productivity and stability in wild populations, and, (ii) if so, to quantify its relative 35 importance compared to other determinants. Capitalizing on 20-year demographic surveys in wild fish 36 populations, we show that genetic diversity does not increase mean biomass production in local 37 populations, but strongly and consistently stabilizes biomass production over time. Genetic diversity 38 accounts for about 20% of explained variance in biomass stability across species, an important 39 contribution about half that of environment and demography (about 40% each). Populations having 40 suffered from demographic bottlenecks in the recent past harbored lower levels of genetic diversity and 41 showed less stability in biomass production over the last 20 years. Our study demonstrates that the loss of 42 intraspecific genetic diversity can destabilize biomass productivity in natural vertebrate populations in just 43 a few generations, strengthening the importance for human societies to adopt prominent environmental 44 policies to favor all facets of biodiversity. 46There is now unequivocal evidence that biodiversity sustains critical ecosystem services that benefit 48 directly to humanity, such as water filtering, pollination and biomass production (1-3). By promoting trait 49 complementarity among species, interspecific diversity allows ecological communities to optimally capture 50 essential resources, transform those resources into biomass and recycle them (4-6). In species-rich 51 communities, these ecological processes are maintained even in the face of environmental variations, 52 thus promoting ecosystem productivity and stability over time (7-9): this is the insurance effect of species 53 richness (10). The drastic erosion in species diversity observed worldwide (11) is hence prejudicial, as it is 54 expected to deeply impair natural ecosystems' capacity to durably sustain human health and wellbeing (2, 55 3). However, the loss of species is only the tip of the iceberg. In most taxa, another form of biodiversity 56 erosion is indeed silently underway: the loss of intraspecific genetic diversity (12, 13). 57Beyond its positive influence on individual fitness and evolutionary rescue (14), intraspecific genetic 58 diversity is expected to play a role similar to species diversity in driving key ecological functions such as 59 biomass production (15, 16). By promo...

Genetic erosion reduces biomass temporal stability in wild fish populations

“…The field sampling protocol was approved by all the prefectures of the departments in which the sampling was carried out. The data generated in this study have been deposited in the Figshare database 38 under accession code https://doi.org/10.6084/ m9.figshare.13095380.v9.…”

Patterns of Epigenetic Diversity in Two Sympatric Fish Species: Genetic vs. Environmental Determinants

“…SNP markers (1892 and 1244 in G. occitaniae and P. phoxinus , respectively) were obtained from the restriction site-associated DNA (RAD) sequencing of pooled DNAs at the site and species levels [ 51 ], using laboratory and bioinformatic procedures described in Prunier et al [ 52 ]. As the DNA of individuals was pooled at the site level, we were unable to retrieve individual genotypes (contrary to microsatellite markers) and we therefore used the frequencies of alleles (from each SNP) at the population level as raw genomic data for the SNPs.…”

Intraspecific diversity loss in a predator species alters prey community structure and ecosystem functions

“…S1). Specifically, the ten selected populations displayed a high level of genetic differentiation (mean pairwise Fst = 0.133, range = 0.029-0.320) and greatly varied in the number of alleles they harbour (from 5.470 alleles in average for the less diverse population to 10.176 alleles for the most diverse population) according to data measured using seventeen microsatellite markers (from Fourtune et al 2018; Prunier et al 2019; Raffard et al 2019a). Moreover, we selected five populations mainly composed of small-bodied adults (mean body mass ± standard error (SE) = 1.03 g ± 0.02) and five populations mainly composed of large-bodied adults (mean body mass ± SE = 3.06 g ± 0.07) (Fig.…”