  Many species reproduce both sexually and asexually producing genetically
unique and clonal recruits. The relative contribution of sexual and asexual
reproduction is mostly considered a consequence of natural selection, for
example, disfavouring sexual propagules during invasions. Here, we present a
novel model for the invasion of species into a new habitat. The model is fully
neutral with respect to the dispersal and the survival of sexual and asexual
recruits. In addition to local dispersal through sexual and asexual
reproduction, long-distance dispersal is implemented through a non-zero
probability for long-range relocations. We parameterized our model using
empirical data on the distribution of asexually and sexually recruited
individuals of the recently established macroalga Fucus radicans over its
current area of distribution, the 8000 year old Baltic Sea. As a solely
stochastic alternative mechanism to natural selection, our simulation results
suggest local abundance of one sex, that during a persistent phase of
establishment will result in a heterogeneous distribution of sexual and asexual
recruits. Specifically, the model suggests an initial general dominance of one
or a few clones, and this pattern is observed in Fucus radicans as well as in
several other species with recent colonization histories.
