Species and genetic diversity relationships in benthic macroinvertebrate communities along a salinity gradient

Abstract

Background Species- and genetic diversity can change in parallel, resulting in a species-genetic diversity correlation (SGDC) and raising the question if the same drivers influence both biological levels of diversity. The SGDC can be either positive or negative, depending on whether the species diversity and the genetic diversity of the measured species respond in the same or opposite way to drivers. Using a traditional species diversity approach together with ultra-conserved elements and high throughput sequencing, we evaluated the SGDCs in benthic macrofauna communities in the Baltic Sea, a geologically young brackish water sea characterised by its steep salinity gradient and low species richness. Assessing SGDCs from six focal marine invertebrate species from different taxonomic groups and with differing life histories and ecological functions on both a spatial and temporal scale gives a more comprehensive insight into the community dynamics of this young ecosystem and the extrinsic factors that might drive the SGDCs. Results No significant correlations between species diversity and genetic diversity were found for any of the focal species. However, both negative and positive trends of SGDCs for the individual focal species were observed. When examining the environmental drivers, no common trends between the species were found, even when restricting the analysis to specific taxonomic classes. Additionally, there were no common environmental factors driving the diversity relationships for species sharing the same SGDC trend (positive or negative). Local population dynamics, together with the invasion history of the individual species and their unique adaptation to the distinctive environment of the Baltic Sea, are expected to be of major influence on the outcome of the SGDCs. Conclusions The present results highlight the importance of assessing SGDCs using multiple species, not just a single indicator species. This emphasises a need to pay attention to the ecology and life history of the focal species. This study also provides insight into the large differences in both patterns and drivers of genetic diversity, which is important when including genetic biodiversity in conservation plans. We conclude that the effects of environmental and biological factors and processes that affects diversity patterns at both the community and genetic levels are likely species dependent, even in an environment such as the Baltic Sea with strong environmental gradients.

Kimura’s Theory of Non-Adaptive Radiation and Peto’s Paradox: A Missing Link?

“…The correlation between species diversity, meaning the number of different species in a community or ecosystem, and genetic diversity has been extensively studied. Genetic diversity within different communities has been shown to have positive, negative, and null relationships with species diversity [ 53 , 54 , 55 , 56 , 57 ]. As the mechanisms governing mutation inputs and substitutions within a lineage are biologically unrelated and occur at different scales (germline vs. organism and population), there seems to be no reason to expect that KD and SR would be so consistently and so uniformly correlated across diverse mammalian lineages a priori ( Figure 4 ).…”

Neutral processes and taxonomic scale drive beta species‐genetic diversity correlations in a submesophotic tropical reef fish

“…SGDCs and their underlying processes have only rarely been evaluated in a marine environment (Manel et al., 2020; Messmer et al., 2012; Petersen et al., 2022; Vilcot et al., 2023), where species generally have greater dispersal capacity, bigger populations and much larger range sizes than in a terrestrial environment (Allen, 2008; Bowen et al., 2020). Two studies focusing on coral reef fishes have formally tested for covariation between genetic and species richness (i.e., α‐diversity) in the Pacific Ocean (Messmer et al., 2012) and Hawaiʻi respectively (Selkoe et al., 2016), but mostly limited to mtDNA.…”