title: Fluctuating helical asymmetry and morphology of snails (Gastropoda) in divergent microhabitats at 'Evolution Canyons I and II,' Israel.
abstract: BACKGROUND
  Developmental instability of shelled gastropods is measured as deviations from a perfect equiangular (logarithmic) spiral. We studied six species of gastropods at 'Evolution Canyons I and II' in Carmel and the Galilee Mountains, Israel, respectively. The xeric, south-facing, 'African' slopes and the mesic, north-facing, 'European' slopes have dramatically different microclimates and plant communities. Moreover, 'Evolution Canyon II' receives more rainfall than 'Evolution Canyon I.'
  
  
  RESULTS
  We examined fluctuating asymmetry, rate of whorl expansion, shell height, and number of rotations of the body suture in six species of terrestrial snails from the two 'Evolution Canyons.' The xeric 'African' slope should be more stressful to land snails than the 'European' slope, and 'Evolution Canyon I' should be more stressful than 'Evolution Canyon II.' Only Eopolita protensa jebusitica showed marginally significant differences in fluctuating helical asymmetry between the two slopes. Contrary to expectations, asymmetry was marginally greater on the 'European' slope. Shells of Levantina spiriplana caesareana at 'Evolution Canyon I,' were smaller and more asymmetric than those at 'Evolution Canyon II.' Moreover, shell height and number of rotations of the suture were greater on the north-facing slopes of both canyons.
  
  
  CONCLUSIONS
  Our data is consistent with a trade-off between drought resistance and thermoregulation in snails; Levantina was significantly smaller on the 'African' slope, for increasing surface area and thermoregulation, while Eopolita was larger on the 'African' slope, for reducing water evaporation. In addition, 'Evolution Canyon I' was more stressful than Evolution Canyon II' for Levantina.
authors: Department of Evolutionary and Environmental Biology, Institute of Evolution, University of Haifa, Haifa, Israel. razshmu@gmail.com
authors: Shmuel
authors: S
authors: Raz
authors: Nathan P
authors: NP
authors: Schwartz
authors: Hendrik K
authors: HK
authors: Mienis
authors: Eviatar
authors: E
authors: Nevo
authors: John H
authors: JH
authors: Graham
mesh_terms: D000818:Animals; D002980:Climate; D017753:Ecosystem; D019143:Evolution, Molecular; D007557:Israel; D011891:Rain; D012399:Rotation; D012908:Snails / Q000033:anatomy & histology*