About Dr Alex Twyford
Dr Twyford’s lab studies the ecology and evolution of flowering plants using both genomic and field-based approaches. In particular, Dr Twyford is interested in gaining insight into the importance of adaptive trait variation and the evolutionary mechanisms underlying diversification. For more information, please visit his website https://twyford.bio.ed.ac.uk/home.
The Enigmatic Evolution of Eyebrights (Euphrasia): Parasitism, Polyploidy & Phenotypic Plasticity
Many biologists have questioned the existence of clear-cut plant species and have instead suggested that species are largely an arbitrary human construct. The question of the discreteness or objectivity of plant species has largely been driven by a handful of taxonomically complex groups where species discrimination is particularly challenging. Here we tackle the nature of species differences in one such ‘nightmare’ group, British eyebrights (Euphrasia), a genus characterised by recent postglacial divergence, hybridisation, parasitism, polyploidy, phenotypic plasticity and self-fertilisation. We use growth experiments with different hosts to understand species differences and to characterise life-history traits, and whole genome sequencing to understand how the extent of hybridization blurs species boundaries. We show that amongst the mess is a gradient of genomic distinctiveness, including a suite of definable genetic units. While hybridisation is extensive, with complete homogenization of genome-wide differences on small isolated islands, species maintain their distinct morphologies in sympatry, and some taxa have specialised host preferences that have evolved in response to the parasitic lifestyle. Our results highlight the need to study evolutionary processes in neglected taxonomically complex groups.