Interspecific patterns of species richness, geographic range size, and body size among New World venomous snakes

Reed, Robert N.

doi:10.1034/j.1600-0587.2003.03388.x

Cited by 63 publications

(92 citation statements)

References 58 publications

(102 reference statements)

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“…Further, the weak support of the historical hypothesis tested here to explain the global pattern of viperid richness does not concur with the proposition of Reed (2003) for New World diversity of Viperidae. According to this author, the viperid richness peak in Central America and southern Mexico may be associated with the historical biogeography of these regions (i.e., the occurrence of several orogenic episodes), which could generate many opportunities for allopatric speciation.…”

Section: Discussioncontrasting

confidence: 64%

“…Furthermore, most of these studies have been geographically restricted to temperate regions, which limits the generalizability of their Wndings (e.g., Rodríguez et al 2005). For snakes, the only investigation focused on macroecological patterns is the one by Reed (2003) and, as far as we know, there are neither global datasets nor global richness analyses for any group of reptiles (but see Lamoreux et al 2006, for an analysis using species list on WWF ecoregions).…”

Section: Electronic Supplementary Materialsmentioning

confidence: 98%

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Global richness patterns of venomous snakes reveal contrasting influences of ecology and history in two different clades

et al. 2008

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Recent studies addressing broad-scale species richness gradients have proposed two main primary drivers: contemporary climate and evolutionary processes (differential balance between speciation and extinction). Here, we analyze the global richness patterns of two venomous snake clades, Viperidae and Elapidae. We used ordinary least squares multiple regression (OLS) and partial regression analysis to investigate to what extent actual evapotranspiration (AET; summarizing current environmental conditions) and biogeographical regions (representing evolutionary effects) were associated with species richness. For viperids, AET explained 45.6% of the variance in richness whereas the effect of this variable for elapids was almost null (0.5%). On the other hand, biogeographic regions were the best predictors of elapid richness (56.5%), against its relatively small effect (25.9%) in viperid richness. Partial regressions also revealed similar patterns for independent effects of climate and history in both clades. However, the independent historical effect in Elapidae decreased from 45.2 to 17.8% when we excluded Australia from the analyses, indicating that the strong historical effect that had emerged for the global richness pattern was reflecting the historical process of elapid radiation into Australia. Even after excluding Australia, the historical signal in elapid richness in the rest of the globe was still significant and much higher than that observed in viperid richness at a global scale (2.7% after controlling for AET effects). Differences in the evolutionary age of these two clades can be invoked to explain these contrasting results, in that viperids probably had more time for diversification, generating richness responses to environmental gradients, whereas the pattern of distribution of elapid richness can be more directly interpreted in an evolutionary context. Moreover, these results show the importance of starting to adopt deconstructive approaches to species richness, since the driving factors of these patterns may vary from group to group according to their evolutionary history.

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Section: Discussioncontrasting

confidence: 64%

Section: Electronic Supplementary Materialsmentioning

confidence: 98%

Global richness patterns of venomous snakes reveal contrasting influences of ecology and history in two different clades

et al. 2008

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“…Among and within turtle species, body size patterns consistent with Bergmann's rule have been observed; however, lizards appear to follow the converse trend (Lindsey 1966;Ashton 2001;Ashton and Feldman 2003). In one study, snakes showed a slight tendency towards a higher proportion of larger species in cooler regions (Lindsey 1966), whereas in more recent intraspecific (Ashton 2001;Ashton and Feldman 2003) and interspecific studies (Reed 2003), there was little support for Bergmann's rule as body size did not increase with latitude.…”

Section: Introductionmentioning

confidence: 78%

“…The most comprehensive assessments of Bergmann's rule to date (e.g., Lindsey 1966;Ashton et al 2000;Ashton 2002b;Ashton and Feldman 2003;Reed 2003) have examined clinal patterns in body size among and within species assemblages. Our study is a more direct test of Bergmann's rule because we examine the pattern using a large data set within a single widely distributed species.…”

Section: Introductionmentioning

confidence: 99%

Clinal variation in body and cell size in a widely distributed vertebrate ectotherm

2004

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Bergmann's rule states that, among conspecific populations, individuals are larger in cooler than in warmer environments as a consequence of selection related to heat conservation. Many of the most comprehensive assessments of Bergmann's rule to date have examined clinal patterns in body size among species assemblages. Our study is a more direct test of Bergmann's rule because we examine the pattern within a single, widely distributed species. We examined geographic variation in body and cell size in the spotted turtle ( Clemmys guttata). Our analysis of 818 turtles collected from the entire range (45-28 degrees N), indicated that body size increased with latitude; however, the relationship was driven by a population of large turtles at the northern extreme of the species' range. When the northern population was removed from the analyses, Bergmann's rule was not supported, and the smallest turtles occurred near the central part of the species' distribution. Recent literature has suggested that latitudinal clines in body size may simply be a physiological byproduct of the effects of temperature on cell division, resulting in larger cells, and hence larger organisms, from cooler temperatures. Measurements of the diameter of skin cells did not support the hypothesis that cell size increases with latitude and decreases with temperature in the spotted turtle, nor was there a significant relationship between body size and cell size. Our study suggests that neither Bergmann's rule nor cell size variation sufficiently explain the body size cline observed in the spotted turtle. We hypothesize that patterns in body size are related to variation in female size at maturity and reproductive cycles.

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“…Evidence supporting this mechanism include a suggested optimal body size for mammals (Marquet and Taper 1998), and a positive relationship between geographic range and body size for endotherms (Brown and Maurer 1989;Brown 1995;DinizFilho and Torres 2002). An optimal body size has been proposed for snakes (Boback and Guyer 2003) and within at least some squamates (venomous snakes of the western hemisphere), geographic range size is positively correlated with body size (Reed 2003).…”

Section: Discussionmentioning

confidence: 99%

Spatial Dynamics of Body Size Frequency Distributions for North American Squamates

2011

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Scale dependent patterns of body size frequency distributions (BSFDs) have been explained by competition and an evolutionarily optimal body size in mammals. We test these ideas in a vertebrate group that is a model for competition and evolutionary studies by assessing the scaledependence of BSFDs. BSFDs (body size defined as maximum total length) of North American squamates were assembled for the entire continent, biomes within the continent and local habitat patches within biomes. We described these distributions using skewness, kurtosis, interquartile range (IQR), and an index of evenness. We compared these parameters among spatial scales using Kolmogorov-Smirnov tests and bootstrap simulations. We assessed the relationship between body size and species richness using correlations (Pearsons and Spearmans R). The North American BSFD is bimodal, with a primary mode (240 mm) corresponding to lizards and small snakes and a secondary mode (912 mm) to snakes. Squamate BSFDs varied in a scale dependent fashion for some biomes and local habitat patches for kurtosis (12% of local patches and 10% of biomes more platykurtic), skewness (30% of biomes skewed to the right) and IQR (12% of patches increased). The index of evenness of BSFDs did not vary with spatial scale. Body size of biomes and local habitat patches closely resembles the North American BSFD as species richness increases. We found limited statistical support for the scale-dependency of North American squamate BSFDs (only 12-30% of patches or biomes conformed to the predicted pattern). These results suggest that the mechanisms implicated in scale-dependent patterns of BSFDs for mammals, geographic turnover of modal-sized species and competition within local assemblages may be of diminished importance in squamates. As geographic turnover of modal-sized species is theoretically linked to an evolutionarily optimal body size, this may suggest that optimal size theory is not adequate to predict spatial scaling of BSFDs in squamates.

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Interspecific patterns of species richness, geographic range size, and body size among New World venomous snakes

Cited by 63 publications

References 58 publications

Global richness patterns of venomous snakes reveal contrasting influences of ecology and history in two different clades

Global richness patterns of venomous snakes reveal contrasting influences of ecology and history in two different clades

Clinal variation in body and cell size in a widely distributed vertebrate ectotherm

Spatial Dynamics of Body Size Frequency Distributions for North American Squamates

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