Molecular phenotyping uncovers differences in basic housekeeping functions among closely related species of hares (Lepus spp., Lagomorpha: Leporidae)

Speciation is a fundamental evolutionary process, which results in genetic
differentiation of populations and manifests as discrete morphological,
physiological as well as behavioral differences. Each species has had its
own evolutionary trajectory, formed by many types of selection pressures
and random drift, making it extremely complicated to associate genetic
differences between the species with the phenotypic differences. In the
present study, we have used an in vitro model to analyze in depth the
genetic and gene regulation differences between fibroblasts of two closely
related mammals, arctic/subarctic mountain hare (Lepus timidus Linnaeus)
and a temperate, steppe-like climate adapted brown hare (Lepus europaeus
Pallas). We discovered the existence of a species-specific expression
pattern of 1,623 genes, manifesting in differences in cell growth,
respiration, and metabolism. Interspecific differences in the housekeeping
functions of fibroblast cells suggest speciation acts on fundamental
processes, even in these two interfertile species. Our results help to
understand the molecular constituents of a species difference on a
cellular level, which could contribute to the maintenance of the species
boundary.