Metapopulation theory Metapopulations, i.e., interconnected populations with extinction- (re)colonization dynamics, are ubiquitous. A key evolutionary feature of metapopulations, as compared to large, long-lived populations, is the genetic bottlenecks during the founding of subpopulations. A common form of subpopulation founding is (re)colonization by the establishment of one or few colonizers which originated from a single source population in an empty habitat patch, the so-called propagule model. Apart from the resulting genetic bottlenecks this entails small effective population sizes, and, as a consequence, inbreeding. 100 100 100 200 200 200 300 300 300 400 400 400 500 500 500 0.0000 0.0005 0.0010 0.0015 0.0020 0.0025 0.0000 0.0005 0.0010 0.0015 0.0020 0.0025 H S H N a a a fixed: s=0 gamma: mean=−0.03, shape=0.2 gamma: mean=−0.05, shape nonsyn DFE: Genomic analyses We propose geographic distance as the best predictor for genomic diversity and differentiation in this metapopulation, while population age is also important, but mainly in regards to effects of population founding. Geographic isolation was measured as mean distance to the two nearest neighboring populations (NN2 [m]) and genomic diversity as π. NN2 was also the best predictor for FST (not shown). Metapopulation processes shape genomic diversity and genomic differentiation Study system We sampled a natural Daphnia magna metapopulation from the Finnish Tvaerminne archipelago. Populations of the cyclically parthenogenetic, freshwater planktonic crustacean D. magna inhabit small rock pools, i.e., depressions in the bare rock of these islands. We aimed to collect 50 adult D. magna from all occupied rock pools and do whole-genome Illumina paired-end sequencing of the pooled individuals of each subpopulation (pool-seq). We obtained data from 60 populations and 1,540,716 SNPs. Pascal Angst, Dieter Ebert, and Peter D. Fields Department of Environmental Sciences, Zoology, University of Basel pascal.angst@unibas.ch @pascalangst R 2 = 0.39, p = 0.001 0 1 2 3 1 2 3 Distance [m] (log10) pairwise FST/(1 − pairwise FST) References van Nouhuys, Saskya (November 2016) Metapopulation Ecology. In: eLS. John Wiley & Sons, Ltd: Chichester. DOI: 10.1002/9780470015902.a0021905.pub2 Haller, B. C., & Messer, P. W. (2019). SLiM 3: Forward Genetic Simulations Beyond the Wright–Fisher Model. Molecular Biology and Evolution, 36(3), 632–637. https://doi.org/10.1093/molbev/msy228 See this poster online at https://doi.org/10.6084/m9.figshare.19095344 or scan here: FS−2 FS−27 FS−29 FS−3 FS−31 FSS−18 G−13 G−18 G−2 G−33 G−42 G−43 G−45 LA−10 LA−18 LA−19 LA−29 LG−7 LG−1 M−62 M−64 SK−1 SK−16 SK−45 SK−49 SK−50 SK−58 SKN−1 SKN−2 SKO−1 SKO−3 SKW−1 0 250 500m K N LON 59.815 59.820 59.825 59.830 23.24 23.25 23.26 Longitude East Latitude North 4e−04 6e−04 8e−04 1e−03 0.0 0.5 1.0 1.5 log10(age + 1) π NN2 [m] 50 100 150 0e+00 5e−04 1e−03 0e+00 5e−04 1e−03 πS πN Research questions Is genetic diversity reduced in newly founded subpopulations of a metapopulation? Are newly founded subpopulations more differentiated from each other than older subpopulations? Do metapopulations evolve differently from large, long-lived, stable populations? R 2 = 0.39, p = 0.001 0 1 2 3 1 2 3 Distance [m] (log10) pairwise FST/(1 − pairwise FST) 0e+00 5e−04 1e−03 0e+00 5e−04 1e−03 πS πN 4e−04 6e−04 8e−04 1e−03 0.0 0.5 1.0 1.5 log10(age + 1) π NN2 [m] 50 100 150 100 100 100 200 200 200 300 300 300 400 400 400 500 500 500 0.0000 0.0005 0.0010 0.0015 0.0020 0.0025 0.0000 0.0005 0.0010 0.0015 0.0020 0.0025 H S H N a a a fixed: s=0 gamma: mean=−0.03, shape=0.2 gamma: mean=−0.05, shape=0.5 nonsyn DFE: 5 Accumulation of deleterious mutations Small population size and recurrent founder events were postulated to lead to an increased rate in the accumulation of deleterious mutations. This would be visible as a genome wide increase in nonsynonymous relative to synonymous nucleotide differences (πN versus πS). Our data confirm this predictio