Genotypic and phenotypic divergence of rodents (Acomys cahirinus and Apodemus mystacinus) at "Evolution Canyon": Micro- and macroscale parallelism

Genetic allozyme and RAPD diversities were examined for ecological-genetic patterns in two rodents, the spiny-mouse Acomys cahirinus (Desmarest, 1819) and woodmouse Apodemus mystacinus (Danford and Alston, 1877), from the eco logically contrasting opposite slopes of the Lower Nahal Oren microsite, Mt . Carmel, Israel, designated by us "Evolution Canyon". Likewise, morphologi cal measurements were compared. Samples of both rodent species were collect ed from six stations: 3 (upper, middle and lower) on the "tropical" xeric S outh-facing slope (SFS) and 3 on the opposite "temperate" mesic North-facin g slope (NFS) which vary dramatically physically and biotically. Higher sol ar radiation on the SFS than on the NFS makes it warmer, drier, spatiotempo rally more heterogeneous and climatically more fluctuating and stressful th an the cooler and more humid NFS. Consequently, the SFS exhibits an open pa rk forest representing an "African" savanna landscape, in sharp contrast wi th the "European" lush liveoak maquis forest. Inter- and intraslope allozym e, RAPD, and morphological divergence was found in both rodents. Local vari ation in solar radiation, temperature and aridity stress caused interslope and intraslope adaptive genotypic (proteins and DNA) and phenotypic (morpho logical, physiological and behavioural) differences paralleling regional pa tterns across Israel in Acomys and in northern and central Israel in Apodem us. This suggests that, at both the micro- and macroscales, diversifying na tural (microclimate) selection appears to be the major evolutionary driving force causing inter- and primarily SFS intraslope adaptive genotypic and p henotypic divergence. "Evolution Canyon" proved in small rodents, as previo usly in other organisms, an optimal model for unravelling evolution in acti on across life and organization.