Final Report Summary - SPATIALDYNAMICS (Ecological, molecular, and evolutionary spatial dynamics)
This project advances our general understanding of the genetic basis of the ecology of populations living in heterogeneous fragmented landscapes. The research is conducted on the Glanville fritillary butterfly, which occurs in a large network of 4,000 meadows in the Åland islands in Finland and has been studied for 22 years as a model system of metapopulation biology. Metapopulations are networks of local populations, of which the Glanville fritillary metapopulation is a prime example.
We have sequenced the full genome of the Glanville fritillary (393 Mb), which is the first butterfly species which has the genome sequenced and which represents the ancestral lepidopteran chromosome number of n = 31. We have also constructed an accurate linkage map with ultra-dense genome-wide SNP data. These resources greatly facilitate the integration of genetic and genomic research with ecological research, which is the primary aim of the project. In a pioneering study, we have reported striking variation in gene expression among local populations with dissimilar demographic histories. Thus female butterflies from newly-established populations expressed more than females from old populations genes associated with egg provisioning and the maintenance of flight capacity. These results provide insight into the molecular mechanisms that underpin previously reported variation in life-history traits and population processes between new versus old local populations. Comparing regional populations living in two fragmented and two continuous habitats in northern Europe, we found that a large number of genes (1,841) were differentially expressed between the landscape types. The results demonstrated that recurrent extinctions of local populations and re-colonizations of unoccupied habitat patches in the fragmented landscape select for a specific gene expression profile, and that butterflies from fragmented landscapes are genetically primed for frequent flight. These results demonstrate that there are genomic adaptations to living in fragmented landscapes. In contrast, we have found that a small island population in the Baltic sea, which has remained completely isolated for about 100 generations, has accumulated a load of deleterious recessive mutations, which compromises its long-term viability. This is an example of what is likely to happen in innumerable ‘remnant’ populations in landscapes fragmented by humans.
We have conducted a series of association studies relating variation in candidate genes to variation in life-history traits, including fecundity, and in measures of individual performance, such as flight metabolic rate. Our research on the metabolic gene phosphoglucose isomerase (Pgi) has produced some of the best evidence for coupled ecological and microevolutionary dynamics in natural populations, making a significant contribution to the conceptual development in the field. These results challenge the commonly held view that evolutionary dynamics occur on such a slow time scale that evolution does not matter for population dynamics. In contrast, our results support the view that microevolutionary and ecological dynamics may be coupled with each other. Such coupling may enhance the response of species to changing environmental conditions due to e.g. climate change and changes in land use. Though such responses will not necessarily save the species that are threatened by global environmental changes, these results allow scientists to better understand the mechanisms involved in the population processes.
We have sequenced the full genome of the Glanville fritillary (393 Mb), which is the first butterfly species which has the genome sequenced and which represents the ancestral lepidopteran chromosome number of n = 31. We have also constructed an accurate linkage map with ultra-dense genome-wide SNP data. These resources greatly facilitate the integration of genetic and genomic research with ecological research, which is the primary aim of the project. In a pioneering study, we have reported striking variation in gene expression among local populations with dissimilar demographic histories. Thus female butterflies from newly-established populations expressed more than females from old populations genes associated with egg provisioning and the maintenance of flight capacity. These results provide insight into the molecular mechanisms that underpin previously reported variation in life-history traits and population processes between new versus old local populations. Comparing regional populations living in two fragmented and two continuous habitats in northern Europe, we found that a large number of genes (1,841) were differentially expressed between the landscape types. The results demonstrated that recurrent extinctions of local populations and re-colonizations of unoccupied habitat patches in the fragmented landscape select for a specific gene expression profile, and that butterflies from fragmented landscapes are genetically primed for frequent flight. These results demonstrate that there are genomic adaptations to living in fragmented landscapes. In contrast, we have found that a small island population in the Baltic sea, which has remained completely isolated for about 100 generations, has accumulated a load of deleterious recessive mutations, which compromises its long-term viability. This is an example of what is likely to happen in innumerable ‘remnant’ populations in landscapes fragmented by humans.
We have conducted a series of association studies relating variation in candidate genes to variation in life-history traits, including fecundity, and in measures of individual performance, such as flight metabolic rate. Our research on the metabolic gene phosphoglucose isomerase (Pgi) has produced some of the best evidence for coupled ecological and microevolutionary dynamics in natural populations, making a significant contribution to the conceptual development in the field. These results challenge the commonly held view that evolutionary dynamics occur on such a slow time scale that evolution does not matter for population dynamics. In contrast, our results support the view that microevolutionary and ecological dynamics may be coupled with each other. Such coupling may enhance the response of species to changing environmental conditions due to e.g. climate change and changes in land use. Though such responses will not necessarily save the species that are threatened by global environmental changes, these results allow scientists to better understand the mechanisms involved in the population processes.