The evolution of large‐scale body size clines in <i>Plethodon</i> salamanders: evidence of heat‐balance or species‐specific artifact?

Adams, Dean C.; Church, James O.

doi:10.1111/j.1600-0587.2011.06911.x

Cited by 32 publications

(42 citation statements)

References 62 publications

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“…the heat conservation hypothesis of Bergmann, 1847; or the heat balance hypothesis of Olalla-T arraga et al, 2006). This result is consistent with the prediction for the inhabitants of wet environments, such as the Amazon and Atlantic forests, and is in line with Adams & Church's (2011) pattern observed in Plethodon salamanders with regard to the discrepancy between cross-species and assemblage-based approaches. Centrolenidae frogs also did not conform to these hypotheses, despite previous reports for this clade at the assemblage level (Gouveia et al, 2013a).…”

Section: Discussionsupporting

confidence: 90%

“…Moreover, our findings reject these hypotheses for four amphibian clades at the species level. Among Plethodon species, Adams & Church (2011) identified P. cinereus as the broad-ranged species influencing the overall pattern (but see Olalla-T arraga et al, 2010). This result is consistent with the prediction for the inhabitants of wet environments, such as the Amazon and Atlantic forests, and is in line with Adams & Church's (2011) pattern observed in Plethodon salamanders with regard to the discrepancy between cross-species and assemblage-based approaches.…”

Section: Discussionsupporting

confidence: 84%

“…species richness) within the grid cells (Slavenko & Meiri, 2015) and the geographical ranges of individual species (Adams & Church, 2011). This approach is referred to as the 'cross-species' approach, which differs from the 'assemblage-based' approach, in which average values of local assemblages are used as sampling units (Olalla-T arraga et al, 2010).…”

Section: Data Analysesmentioning

confidence: 99%

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Geographical clines of body size in terrestrial amphibians: water conservation hypothesis revisited

Gouveia

Correia

2016

Journal of Biogeography

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Aim Faced with the dispute regarding spatial gradients of body size in ectotherms, we build upon their long‐known allometric relationship with water economy, which scales with thermal and hydric regimes, to revisit and refine the water conservation hypothesis (WCH). We provide a brief description of the WCH, including its physiological basis and geographical predictions for body size clines in terrestrial amphibians, and test it against heat‐based hypotheses in four amphibian clades. Location The Americas. Methods We employ phylogenetic comparative analyses to examine relationships between body size and both temperature, as a descriptor of the effect of heat alone, and potential evapotranspiration, which describes the water constraint along evaporative gradients. We assess these relationships in four amphibian clades: the subfamily of leaf frogs (Phyllomedusinae), genera of gladiator frogs (Hypsiboas), salamanders (Plethodon) and the family of glass frogs (Centrolenidae). Results Three clades did not show phylogenetic signals in body size variation. In addition, three clades showed a positive relationship with potential evapotranspiration as predicted, and all of them were unrelated to temperature. When present, however, the explanatory power of evaporative energy on body size variation was relatively weak. Main conclusions The conservation of water across evaporative gradients is both a more comprehensive explanation and a more pervasive driver of spatial clines in body size among terrestrial amphibians than is the balance of heat alone. However, the relatively low predictive ability of evaporative energy and its dependence on specific climatic configurations both emphasize and elucidate the non‐universality of the phenomenon.

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Section: Discussionsupporting

confidence: 90%

Section: Discussionsupporting

confidence: 84%

Section: Data Analysesmentioning

confidence: 99%

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Geographical clines of body size in terrestrial amphibians: water conservation hypothesis revisited

Gouveia

Correia

2016

Journal of Biogeography

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“…Furthermore, it does not account for phylogeny, the effect of which seems to be very large in determining amphibian body size (as is evident in the high values of λ). Therefore, trends in body size distributions uncovered using grid‐cell methods probably do not represent changes in the population level in response to selection, as natural selection does not act on cross‐species averages (Adams & Church, ; Gaston & Chown, ). Rather, observed anuran body size trends could be driven by a few, wide‐ranging species, for example the medium‐sized Lithobates sylvaticus (the only anuran in much of northern Canada and Alaska), Bufo bufo and Rana temporaria (the only anurans in most of the British Isles and Scandinavia, and the largest anurans in Europe), and be more related to community assembly rather than size evolution.…”

Section: Discussionmentioning

confidence: 99%

Mean body sizes of amphibian species are poorly predicted by climate

Slavenko

Meiri

2015

Journal of Biogeography

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Aim Climate is thought to exert a strong influence on animal body sizes. We examined the relationship between amphibian body size and several climatic variables to discern which climatic variables, if any, affect amphibian size evolution. Location Europe and North America. Methods We assembled a dataset of mean sizes of 356 (out of 360) amphibian species in Europe, the USA and Canada, and tested how they are related to temperature, precipitation, primary productivity and seasonality. First, we examined the body size distributions of all the species inhabiting equal‐area grid cells (of 96.3 km × 96.3 km) using randomizations to account for the effects of species richness. Second, we examined the relationship between mean species body size and the environmental predictors across their ranges accounting for phylogenetic effects. Results The observed amphibian body size distributions were mostly statistically indistinguishable from distributions generated by random assignment of species to cells. Median sizes in grid cells were negatively correlated with temperature in anurans and positively in urodeles. The phylogenetic analysis revealed opposite trends in relation to temperature. In both clades most climatic variables were not associated with size and the few significant relationships were very weak. Main conclusions Spatial patterns in amphibian body size probably reflect diversity gradients, and relationships with climate could result from spurious effects of richness patterns. The large explanatory power of richness in the grid‐cell analysis, and the small explanatory power of climate in the interspecific analysis, signify that climate per se has little effect on amphibian body sizes.

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“…Finally, because of discussion of the relationship between phylogenetic generalized least‐squares (PGLS) and PVR (Adams and Church 2011, Freckleton et al 2011), we also compared S‐component from PVR with a PGLS transform of log‐body size, following Garland and Ives (2000, p. 361). The idea is to calculate a vector Z , given by…”

Section: Methodsmentioning

confidence: 99%

On the selection of phylogenetic eigenvectors for ecological analyses

et al. 2012

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Among the statistical methods available to control for phylogenetic autocorrelation in ecological data, those based on eigenfunction analysis of the phylogenetic distance matrix among the species are becoming increasingly important tools. Here, we evaluate a range of criteria to select eigenvectors extracted from a phylogenetic distance matrix (using phylogenetic eigenvector regression, PVR) that can be used to measure the level of phylogenetic signal in ecological data and to study correlated evolution. We used a principal coordinate analysis to represent the phylogenetic relationships among 209 species of Carnivora by a series of eigenvectors, which were then used to model log‐transformed body size. We first conducted a series of PVRs in which we increased the number of eigenvectors from 1 to 70, following the sequence of their associated eigenvalues. Second, we also investigated three non‐sequential approaches based on the selection of 1) eigenvectors significantly correlated with body size, 2) eigenvectors selected by a standard stepwise algorithm, and 3) the combination of eigenvectors that minimizes the residual phylogenetic autocorrelation. We mapped the mean specific component of body size to evaluate how these selection criteria affect the interpretation of non‐phylogenetic signal in Bergmann's rule. For comparison, the same patterns were analyzed using autoregressive model (ARM) and phylogenetic generalized least‐squares (PGLS). Despite the robustness of PVR to the specific approaches used to select eigenvectors, using a relatively small number of eigenvectors may be insufficient to control phylogenetic autocorrelation, leading to flawed conclusions about patterns and processes. The method that minimizes residual autocorrelation seems to be the best choice according to different criteria. Thus, our analyses show that, when the best criterion is used to control phylogenetic structure, PVR can be a valuable tool for testing hypotheses related to heritability at the species level, phylogenetic niche conservatism and correlated evolution between ecological traits.

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The evolution of large‐scale body size clines in Plethodon salamanders: evidence of heat‐balance or species‐specific artifact?

Cited by 32 publications

References 62 publications

Geographical clines of body size in terrestrial amphibians: water conservation hypothesis revisited

Geographical clines of body size in terrestrial amphibians: water conservation hypothesis revisited

Mean body sizes of amphibian species are poorly predicted by climate

On the selection of phylogenetic eigenvectors for ecological analyses

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