The genetic basis of Lifespan: Nailing down novel candidate genes
Background
Life history traits such as diapause, lifespan and growth are closely linked to fitness, and have therefore traditionally been hypothesised to be under strong selection in wild populations. Unexpectedly, many populations in fact show substantial genetic variation for these traits, which leads to the question why selection has not eliminated this variation. If habitats vary dynamically over space and time, selection may maintain alternative alleles for a gene, if these alleles each have highest fitness in alternating ecological conditions. To clarify this fundamental issue and test this hypothesis, it is therefore crucial to resolve the links between specific alleles and their life history phenotypes. Beyond clarifying a fundamental evolutionary question, understanding the genetic basis of lifespan has critical applications for human health.
The Glanville fritillary butterfly is a classic model species in ecology and evolution, and its natural history, demography and ecology have been studied for decades in the field and laboratory. More recently, our lab has made substantial progress in understanding the genetic basis of adaptive life history variation, combining ecological experiments with new genomic approaches.
Lifespan is a key fitness trait, and together with other traits such as reproduction and growth, it is part of a suite of alternative life history strategies hypothesised to be favoured by fluctuating environmental conditions. As in many animals, lifespan is likely regulated by systemic hormonal signals and other genetic factors.
In this project, we will test the involvement of candidate genes and other loci in regulating these important traits. These genes are likely to play key roles in lifespan, as we have recently identified them as associated with lifespan in large, genome-wide screens.
Objectives
To select key candidate genes based on literature and genome-wide screens.
To design an experiment that will associate allelic variants for these genes with specific lifespan phenotypes of individual butterflies, exploiting our large library of existing samples.
To design primers that distinguish these variants in the genome, and perform PCR and quantitative PCR experiments on genomic DNA from individuals with phenotypes of interest.
To statistically analyse resulting data and test for each gene its association with diapause or lifespan.
To write a BSc or MSc thesis in the format of a scientific paper.
Methods & Learning outcomes
- scientific experimental design, including power analysis
- data mining and bioinformatics
- primer design and sequence analysis (alignments, blast)
- general molecular biology laboratory methods
- PCR and qPCR (melt-curve and endpoint genotyping on Roche Lightcycler)