I am pleased to announce that I have been awarded an ERC Starting Grant. In this five year research program I will untangle the evolution of balanced lethal systems. Natural selection is supposed to keep lethal alleles (dysfunctional copies of crucial genes) in check. Yet, in a balanced lethal system the frequency of lethal alleles is inflated. Because two forms of a chromosome (let’s call them A and B) carry distinct lethal alleles that are reciprocally compensated for by functional genes on the alternate chromosome form, both chromosome forms – and in effect their linked lethal alleles – are required for survival (see figure below). The inability of natural selection to purge balanced lethal systems appears to defy evolutionary theory.

The most illustrious balanced lethal system is observed in Triturus newts and is known as chromosome 1 syndrome. All adult Triturus newts invariably possess two forms of chromosome 1, known as 1A and 1B. Yet, according to the rules of Mendelian inheritance, half of the offspring produced is homozygous (possessing two copies of chromosome 1A or 1B). These homozygotes die halfway embryological development – half of Triturus embryos never hatch! All we currently know about chromosome 1 syndrome derives from classical karyological studies, mainly by Herbert Macgregor and colleagues. Taking advantage of modern genetic techniques, my research team will determine the genomic basis of chromosome 1 syndrome and we will propose a new model on how these bizarre balanced lethal systems could evolve. Keep an eye out on the Wielstra lab* website for all the awesome research that will derive from my ERC Starting Grant.

*Yes, I am allowed to say Wielstra lab now.