Does photoperiodism promote hybrid zones at higher latitudes and
biodiversity globally?
Kari Saikkonen
University of Turku
Corresponding Author:karisaik@utu.fi
Author ProfileAbstract
Hybridization is accepted as a common and important evolutionary force
in plants and animals. It can occur randomly or in spatially and
temporarily dynamic hybrid zones where the geographic ranges of closely
related species meet. Here, I propose that poleward increases in the
seasonality of day length promote the maintenance of circumpolar hybrid
zones at higher latitudes. Hybridization at higher latitudes should be
most prevalent among species that use seasonal changes in day length to
coordinate their reproductive phenology but may apply to other species
as well if their fitness is dependent on species that are adapted to
photoperiodic cues. Given that climate change is expanding species
ranges across latitudes and creating opportunities for reproductive
interactions between formerly isolated and genetically distinct
populations and species, a better understanding of the evolutionary role
of hybridization and its consequences for biodiversity, ecosystem
functions and services is needed. At the global scale, I predict that
day length-promoted circumpolar hybrid zones and consequent hybrid
speciation are play significant roles in maintaining genetic admixture
and species diversity on a geological time scale because species' range
shifts across latitudes during the cycles of Earth's cooler and warmer
periods cause recurrent isolation of and contact among species.