# Sebastian Bossert

Competing selective sweeps

In population genetics, mathematical models are used to study the distributi-

ons and changes of allele frequencies. Main evolutionary factors influencing these

frequencies are (among others) mutation, selection and recombination. Maynard

Smith and Haigh (1974) analysed in a pioneering theoretical framework the process

when a new, strongly selected advantageous mutation becomes fixed in a popula-

tion. They identified that such an evolution, called selective sweep, leads to the

reduction of diversity around the selective locus. In the following years other scien-

tists faced the question to what extent this characteristic still holds, when certain

assumptions are modified.

In this talk a situation is presented where two selective sweeps within a narrow

genomic region overlap in a sexually evolving population. For such a competing

sweeps situation the probability of a fixation of both beneficial alleles, in cases

where these alleles are not initially linked, is examined. To handle this question

a graphical tool, the ancestral selection recombination graph, is utilized, which

is based on a genealogical view on the population. This approach provides a li-

mit result (for large selection coefficients) for the probability that both beneficial

mutations will eventually fix. The analytical examination is complemented by si-

mulation results.