Is the Rapoport effect widespread? Null models revisited

Abstract

Aim To test the Rapoport effect using null models and data sets taken from the literature. We propose an improvement on an existing method, testing the Rapoport effect in elevational and latitudinal distributions when distributions are restricted by sampling.Location Global.Methods First, we hypothesized that real range size distributions are similar to those expected by null assumptions (expected by only imposing boundaries to species distributions). When these distributions were different from those expected under the null assumptions, we tested the hypothesis that these distributions correspond to those expected when a Rapoport effect occurs. We used two simulation methods, random and pseudo-random, which differed only in that the latter one assumes fixed species mid-points, coinciding with real mid-points. Observed correlations between range size and mid-point were compared with the frequency distribution of 1000 simulations, using both simulation methods. We compared the correlation curves generated by 1000 simulations with those of the observed distributions, testing whether correlations indicated a Rapoport effect.Results Several significant patterns of correlations between range size and mid-point were observed in the data sets when compared with random and pseudo-random simulations. However, few of these correlations were consistent with a Rapoport effect. Main conclusionsAlthough some recent studies are consistent with a Rapoport effect, our results suggest that the Rapoport effect is not a widespread pattern in global ecology.Several authors have noticed the coincident patterns of Rapoport's rule and the gradient in species richness and have looked for a causal relationship between these patterns, but results are still

The latitudinal and bathymetric ranges of marine fishes: a global analysis to test the application of Rapoport′s Rule

“…2005; Almeida‐Neto et al. 2006; Harcourt 2006; Kendall & Haedrich 2006; Morin & Chuine 2006; Ribas & Schoereder 2006). Other studies, however, have tended to refute the rule (Rohde et al.…”

“…1996; Kerr 1999; Fu et al. 2004; Bhattarai & Vetaas 2006; Kendall & Haedrich 2006; Ribas & Schoereder 2006; Stauffer & Rohde 2006).…”

Rapoport's Rule: Do climatic variability gradients shape range extent?

“…Using this method, he found that latitudinal range extent of marine and freshwater fishes is greatest at low (rather than high) latitudes, contrasting with Stevens (1989) who found no consistent Rapoport effect in marine environments (in accordance with his prediction that bathymetric variability gradients overlying latitudinal gradients would conceal the effect). Species with midpoints in the middle of an area, however, will have the largest possible range extents (Colwell and Hurtt 1994, Blackburn and Gaston 1996, Lyons and Willig 1997, Ribas and Schoereder 2006,Šizling et al 2009). In any given sampling area, endemic species with midpoints close to the boundaries of the predefined area are necessarily restricted to a small maximum potential latitudinal range extent, since they can by definition not extend farther in one direction from the midpoint than in the other and are therefore restricted in their range size by the geometric boundaries of the study area.…”

“…Some recent studies have addressed these statistical challenges by using randomization to compare results to appropriate null models (Lyons and Willig 1997, Diniz-Filho and Tôrres 2002, Ribas and Schoereder 2006, Beketov 2009, Davies et al 2011, Morin and Lechowicz 2011, Morin and Lechowicz 2013, by using more advanced grid-cell analyses over a two-dimensional landscape (Smith et al 1994, Meliadou and Troumbis 1997, Ruggiero et al 1998, Ruggiero and Hawkins 2006, Morin and Lechowicz 2011, Luo et al 2011, Whitton et al 2012, Morales-Castilla et al 2013, Morin and Lechowicz 2013 accounting for more complex climate patterns than simple latitudinal gradients, or by using quartile analyses to assess the impact of different groups of range sizes within the data set (e.g., by using only restricted-range species [Amend et al 2013, McCain and Knight 2013, Morin and Lechowicz 2013). However, evidence for Rapoport's Rule remains equivocal.…”

Rapoport's rule, species tolerances, and the latitudinal diversity gradient: geometric considerations

“…Some studies dealt with possible biases in the data (Blackburn and Gaston 1996), demonstrating that the pattern is confined only to particular latitudes () and is not symmetric about the equator (Gaston and Chown 1999 a , ). Only a few studies have compared the observed patterns with null models, and not all were explicit about the assumed underlying mechanisms (, Lyons and Willig 1997, , Grytnes and Vetaas 2002, Arita 2005, Ribas and Schoereder 2006). Only ) and Gryntes and Vetaas (2002) considered possible trends in potential range sizes as factors affecting underlying mechanisms.…”