title: Predictors of shell size in long-lived lake gastropods.
abstract: OBJECTIVE
  To investigate shell size variation among gastropod faunas of fossil and recent long-lived European lakes and discuss potential underlying processes.
  
  
  METHODS
  Twenty-three long-lived lakes of the Miocene to Recent of Europe.
  
  
  METHODS
  Based on a dataset of 1412 species of both fossil and extant lacustrine gastropods, we assessed differences in shell size in terms of characteristics of the faunas (species richness, degree of endemism, differences in family composition) and the lakes (surface area, latitude and longitude of lake centroid, distance to closest neighbouring lake) using multiple and linear regression models. Because of a strong species-area relationship, we used resampling to determine whether any observed correlation is driven by that relationship.
  
  
  RESULTS
  The regression models indicated size range expansion rather than unidirectional increase or decrease as the dominant pattern of size evolution. The multiple regression models for size range and maximum and minimum size were statistically significant, while the model with mean size was not. Individual contributions and linear regressions indicated species richness and lake surface area as best predictors for size changes. Resampling analysis revealed no significant effects of species richness on the observed patterns. The correlations are comparable across families of different size classes, suggesting a general pattern.
  
  
  CONCLUSIONS
  Among the chosen variables, species richness and lake surface area are the most robust predictors of shell size in long-lived lake gastropods. Although the most outstanding and attractive examples for size evolution in lacustrine gastropods come from lakes with extensive durations, shell size appears to be independent of the duration of the lake as well as longevity of a species. The analogue of long-lived lakes as 'evolutionary islands' does not hold for developments of shell size because different sets of parameters predict size changes.
authors.affiliation: Geological-Palaeontological Department Natural History Museum Vienna 1010 Vienna Austria.
authors.forename: Thomas A
authors.identifier: 0000-0002-1398-9941
authors.initials: TA
authors.lastname: Neubauer
authors.affiliation: Geological-Palaeontological Department Natural History Museum Vienna 1010 Vienna Austria.
authors.forename: Elisavet
authors.initials: E
authors.lastname: Georgopoulou
authors.affiliation: Geological-Palaeontological Department Natural History Museum Vienna 1010 Vienna Austria.
authors.forename: Mathias
authors.initials: M
authors.lastname: Harzhauser
authors.affiliation: Geological-Palaeontological Department Natural History Museum Vienna 1010 Vienna Austria.
authors.forename: Oleg
authors.initials: O
authors.lastname: Mandic
authors.affiliation: Geological-Palaeontological Department Natural History Museum Vienna 1010 Vienna Austria.
authors.forename: Andreas
authors.initials: A
authors.lastname: Kroh
keywords: Ancient lakes; freshwater gastropods; lake surface area; shell size; species richness; species–area relationship