We work primarily with various waterflea species of the genus Daphnia
THE HOSTS
For over a century, Daphnia has been a powerful model organism for understanding the genetics of infectious disease and local adaptation. Their short generation time (12 days), ease of culturing, and ability to reproduce clonally, is ideally suited to evolutionary genetics, as genotypes (i.e. clones) can be replicated extensively.
With their adoption as the 13th official model organism (nih.gov), there is now a wealth of genomic tools available for unravelling the genetic architecture of infection.
THE PATHOGENS
Daphnia are host to numerous pathogens including bacteria, fungi, microsporidia and helminths.
One of the most common pathogens of D. magna is the the spore forming bacteria Pasteuria ramosa. This pathogen is genetically diverse, easily stored (spores can be frozen) and only transmitted horizontally. Pasteuria is extremely virulent, resulting in complete castration of the host and a vastly reduced life expectancy.
THE ENVIRONMENT
Daphnia are small (1-5 mm), transparent crustaceans that occupy a range of freshwater habitats – from rocky coastal rock pools, to desert ponds and mountain lakes.
This system offers a unique opportunity to unravel the genetic basis of local adaptation, as populations have repeatedly evolved differences in life-history traits – Daphnia from rock-pool habitats develop faster, show elevated levels of early reproduction, and greater intrinsic mortality rates.