Download Prof. Eviatar Nevo, University of Haifa, Israel

“Evolution Canyon” model: A microcosm evolution of life
Eviatar Nevo
Institute of Evolution, University of Haifa, Mount Carmel, Haifa 31905
Biodiversity evolution and the relative importance of forces driving evolution of genotypes and
phenotypes require more critical testing and generalizations across phylogeny. In the long-term research
project at the "Evolution Canyon" (“EC” I) model microsite, Lower Nahal Oren, Mount Carmel, and
Lower Nahal Keziv, Upper Galilee (“EC” II), Israel, we seek to draw generalizations across life and
organizational levels and to highlight controversial and unresolved problems of biological evolution. The
opposite slopes of "Evolution Canyons" display dramatic physical and biotic contrasts at a microscale.
Higher solar radiation (up to 600% more) on the South-Facing Slope (SFS) makes it warmer, drier, and
spatiotemporally more heterogeneous and fluctuating than the North-Facing Slope (NFS), even though
the slopes are separated by only 100 m at the bottom and 400 m at the top. Across phylogeny, in bacteria,
plants and animals the tropical Afro-Asian warm and xeric SFS savanna is richer than the NFS in species
of terrestrial taxa. In contrast, the temperate Euro-Asian cooler and mesic NSF is richer than the SFS in
reproductively water-dependent lower plants and fungi, thus displaying global patterns locally despite the
possibilty of mixing by easy migration across the microsite. To date, we have identified 2500 species in
“EC I” and 1000 species in “EC II”, many displaying qualitative or quantitative divergence between and
within slopes. As predicted, genetic diversity was higher on the more heterogeneous and stressful SFS of
“EC I” in 11 of 14 model organisms (lichen, wild barley, landsnails, earthworm, diplopod, beetles and
rodents). Remarkably, heritable mutation rates in the soil fungus Sordaria fimicola was higher threefold,
and male recombination in Drosophila melanogaster fourfold, on the SFS. Adaptive complexes
contributing in different organisms in morphology, physiology, behaviour and life history have been
demonstrated between and within the slopes, partly by transplant experiments. We hypothesize that
microclimatic diversifying natural selection, overriding migration and stochasticity, appears here to be a
major evolutionary driving force of genotypic and phenotypic evolution. Recently, we described incipient
sympatric speciation in Drosophila malanogaster fruit flies and in Sordaria fimicola, soil fungi. Incipient
speciation may prove a common phenomenon across life in “Evolution Canyon”. Future in-depth analysis
of the mechanisms, kind, degree, and stage of selection are planned. Likewise, critical fitness
experiments are planned including transplant experiments and QTL mappingz, are planned to unravel the
genetic basis of adaptation and speciation in model organisms differing in mating and migration systems.
The "Evolution Canyon" microsite provides a fertile microgeographic critical testing model of
biodiversity evolution, especially exploring the dynamics of adaptation (Nevo, 2001) due to its sharp
microscale ecological slope contrasts.
1. Nevo, E. 1995. Asian, African and European biota meet at “Evolution Canyon”, Israel: Local tests of
global biodiversity and genetic diversity patterns. Proc. Roy. Soc. Lond. B 262:149-155.
2. Nevo, E. 1997. Evolution in action across phylogeny caused by microclimatic stresses at “Evolution
Canyon”. Theor. Pop. Biol. 52:231-243.
3. Nevo, E. 2001.Evolution of Genome-Phenome Diversity Under Environmental Stress. Proc. Natl. Aca. Sci.
USA 98:6233-6240.
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