Varpu Pärssinen

Doctoral Student


Lost between two worlds: Are hybrids less adapted to their environment?

My PhD projects dives into the mechanics of speciation by studying ecological hybrid inviability. When populations start to diverge, there are a number of reproductive barriers expected to appear in order to prevent these populations from merging again. One of these barriers is the natural selection against hybrids produced between these populations. If the parents have evolved in different environments, the hybrid offspring should be only suboptimally adapted to either, causing them to have lower fitness. However, only a few studies have demonstrated this phenomenon so far.

My main study species is the Bahamas mosquitofish (Gambusia hubbsi), which lives in small isolated populations in blue holes across the Bahamas. These blue holes differ very little in their living conditions and species compositions, the presence of piscivorous fish being the main driver of divergent evolution in the mosquitofish. This makes the mosquitofish an excellent model to study the evolution of reproductive barriers, with relatively few variables to keep track of.

I´m interested in finding out if hybrids between high-predation and low-predation populations are suboptimal in their predator-avoidance or competition abilities. Working together with the Langerhans Lab in North Carolina, I can study the intrinsic differences of these abilities in laboratory conditions, while also observing other possible pre- and postmating barriers. This study system allows me to compare the comparative strengths of reproductive barriers at the time of early species divergence.

Recent research outputs

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