Browsing by Subject "Lifespan"

Lifespan is a key fitness trait, together with fecundity, dispersal, and growth. In addition to environmental factors shaping variation in lifespan, it is also influenced by genetic components. Based on theory, genetic variation in lifespan is expected to be reduced due to its high relevance to fitness. However, due to trade-offs between different life-history traits and the variable or unstable environmental conditions organisms face in nature, life-history traits are also expected to sustain higher genetic variation. From studies in model organisms, such as the fruit fly and the roundworm, researchers have uncovered key insights into the genetic basis of lifespan. Some genes have been shown to contribute more to lifespan than others and different species seem to share homologous genes influencing lifespan that have been conserved. Many of these genes relate to the insulin receptors and insulin signaling processes. The allelic variation and over- or under-expression of these genes have been shown to be associated with changes in lifespan. However, regardless of our accumulating knowledge of these genes in impacting lifespan under laboratory conditions, we have little understanding of the role of these genes impacting variation in lifespan under more natural conditions. In general, assessment of genes affecting variation in lifespan in natural populations is rare, even under circumstances where we know that the lifespan has a heritable component. The Glanville fritillary (Melitaea cinxia) is a butterfly that inhabits most of Europe. It is used as a model species in ecology and evolution in relation to metapopulation dynamics and spatially structured habitats. It has been studied extensively both under experimental conditions and via observational studies in the field. The Glanville fritillary butterfly works as a good model organism for assessments of genetic components of life-history variation, as vast amounts of genomic and ecological data are already available. In this thesis, I aim to shed light on the genetic background of lifespan by using the Glanville fritillary as a model organism. More specifically, I will test the association of some well-known lifespan-related candidate genes with a phenotypic variation on the butterfly’s adult lifespan based on previously obtained experimental data on individuals collected from the natural metapopulation during the larval stage.