An environmental gradient dominates ecological and genetic differentiation of marine invertebrates between the North and Baltic Sea. Issue 5 (20th May 2022)

• Record Type: Journal Article
• Authors: Geburzi, Jonas C.; Heuer, Nele; Homberger, Lena; Kabus, Jana; Moesges, Zoe; Ovenbeck, Kira; Brandis, Dirk; Ewers, Christine
• Is Part Of: Ecology and evolution. Volume 12:Issue 5(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-05-20
• Subjects: adaptation -- Baltic Sea -- cytochrome oxidase -- genetic differentiation -- marine invertebrates -- North Sea -- population genetics -- salinity; Ecology -- Periodicals; Evolution -- Periodicals; 577.05
• DOI: 10.1002/ece3.8868
• Languages: English
• ISSNs: 2045-7758

Abstract

Abstract: Environmental gradients have emerged as important barriers to structuring populations and species distributions. We set out to test whether the strong salinity gradient from the marine North Sea to the brackish Baltic Sea in northern Europe represents an ecological and genetic break, and to identify life history traits that correlate with the strength of this break. We accumulated mitochondrial cytochrome oxidase subunit 1 sequence data, and data on the distribution, salinity tolerance, and life history for 28 species belonging to the Cnidaria, Crustacea, Echinodermata, Mollusca, Polychaeta, and Gastrotricha. We included seven non‐native species covering a broad range of times since introduction, in order to gain insight into the pace of adaptation and differentiation. We calculated measures of genetic diversity and differentiation across the environmental gradient, coalescent times, and migration rates between North and Baltic Sea populations, and analyzed correlations between genetic and life history data. The majority of investigated species is either genetically differentiated and/or adapted to the lower salinity conditions of the Baltic Sea. Species exhibiting population structure have a range of patterns of genetic diversity in comparison with the North Sea, from lower in the Baltic Sea to higher in the Baltic Sea, or equally diverse in North and Baltic Sea. Two of the non‐native species showed signs of genetic differentiation, their times since introduction to the Baltic Sea being about 80 and >700 years, respectively. Our results indicate that the transition from North Sea to Baltic Sea represents a genetic and ecological break: The diversity of genetic patterns points toward independent trajectories in the Baltic compared with the North Sea, and ecological differences with regard to salinity tolerance are common. The North Sea–Baltic Sea region provides a unique setting to study evolutionary adaptation during colonization processes at different stages by jointly considering native and non‐native species. Abstract : Environmental gradients have emerged as important barriers to structuring populations and species distributions. Using ecological and genetic data, we show that marine invertebrates exhibit significant structure across a strong salinity gradient from marine to brackish water. The length of the planktonic larval phase may be the sticking point for the colonization of brackish environments, as species with long‐lived planktonic larvae did not occur at lower salinities.