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Cross-taxon congruence and environmental conditions.

Toranza C, Arim M - BMC Ecol. (2010)

Bottom Line: We found a positive association between avian and mammal richness and a positive latitudinal trend for both groups in the Brazilian Cerrado.However, an association between avian and mammal diversity remains significant.The approaches introduced here indicate that the prevalence of a significant association among taxa, after considering the environmental determinant, could indicate both the need to incorporate additional processes (e.g. biogeographic and evolutionary history or trophic interactions) and/or the existence of a shared trend in detection biases among taxa and regions.

View Article: PubMed Central - HTML - PubMed

Affiliation: Facultad de Ciencias, Instituto de Ecología y Ciencias Ambientales, Universidad de la República, Uruguay, Iguá 4225 Piso 8 Sur, Montevideo, Uruguay. ctoranza@gmail.com

ABSTRACT

Background: Diversity patterns of different taxa typically covary in space, a phenomenon called cross-taxon congruence. This pattern has been explained by the effect of one taxon diversity on taxon diversity, shared biogeographic histories of different taxa, and/or common responses to environmental conditions. A meta-analysis of the association between environment and diversity patterns found that in 83 out of 85 studies, more than 60% of the spatial variability in species richness was related to variables representing energy, water or their interaction. The role of the environment determining taxa diversity patterns leads us to hypothesize that this would explain the observed cross-taxon congruence. However, recent analyses reported the persistence of cross-taxon congruence when environmental effect was statistically removed. Here we evaluate this hypothesis, analyzing the cross-taxon congruence between birds and mammals in the Brazilian Cerrado, and assess the environmental role on the spatial covariation in diversity patterns.

Results: We found a positive association between avian and mammal richness and a positive latitudinal trend for both groups in the Brazilian Cerrado. Regression analyses indicated an effect of latitude, PET, and mean temperature over both biological groups. In addition, we show that NDVI was only associated with avian diversity; while the annual relative humidity, was only correlated with mammal diversity. We determined the environmental effects on diversity in a path analysis that accounted for 73% and 76% of the spatial variation in avian and mammal richness. However, an association between avian and mammal diversity remains significant. Indeed, the importance of this link between bird and mammal diversity was also supported by a significant association between birds and mammal spatial autoregressive model residuals.

Conclusion: Our study corroborates the main role of environmental conditions on diversity patterns, but suggests that other important mechanisms, which have not been properly evaluated, are involved in the observed cross-taxon congruence. The approaches introduced here indicate that the prevalence of a significant association among taxa, after considering the environmental determinant, could indicate both the need to incorporate additional processes (e.g. biogeographic and evolutionary history or trophic interactions) and/or the existence of a shared trend in detection biases among taxa and regions.

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Cross-taxon congruence of avian and mammal richness within the Cerrado region. Relationships between avian and mammal richness in the Brazilian Cerrado. Line indicate the polynomic regression fit between groups (r2 = 0.574, P < 0.05, N = 181).
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Figure 2: Cross-taxon congruence of avian and mammal richness within the Cerrado region. Relationships between avian and mammal richness in the Brazilian Cerrado. Line indicate the polynomic regression fit between groups (r2 = 0.574, P < 0.05, N = 181).

Mentions: Species richness of birds and mammals was positively associated in the Cerrado biome (r2 = 0.574, P < 0.05, N = 181), as had been previously noted in a study on the spatial patterns of vertebrate diversity in this region [41]. The relationship between taxon richness was mainly positive and non-linear, but tended to be independent at high values of richness (Figure 2). Species richness of birds (r2 = 0.292, P < 0.05, N = 181) and mammals (r2 = 0.689, P < 0.05, N = 181) showed a positive latitudinal trend in the Brazilian Cerrado region. This result is consistent with diversity trends previously reported in this biome for amphibians [47] and birds [43]. The functional form of the latitudinal trend was different for birds and mammals. Mammal richness presented a positive but non-linear monotonic pattern (Figure 3a), while avian richness showed a positive linear relationship with latitude (Figure 3b).


Cross-taxon congruence and environmental conditions.

Toranza C, Arim M - BMC Ecol. (2010)

Cross-taxon congruence of avian and mammal richness within the Cerrado region. Relationships between avian and mammal richness in the Brazilian Cerrado. Line indicate the polynomic regression fit between groups (r2 = 0.574, P < 0.05, N = 181).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2914051&req=5

Figure 2: Cross-taxon congruence of avian and mammal richness within the Cerrado region. Relationships between avian and mammal richness in the Brazilian Cerrado. Line indicate the polynomic regression fit between groups (r2 = 0.574, P < 0.05, N = 181).
Mentions: Species richness of birds and mammals was positively associated in the Cerrado biome (r2 = 0.574, P < 0.05, N = 181), as had been previously noted in a study on the spatial patterns of vertebrate diversity in this region [41]. The relationship between taxon richness was mainly positive and non-linear, but tended to be independent at high values of richness (Figure 2). Species richness of birds (r2 = 0.292, P < 0.05, N = 181) and mammals (r2 = 0.689, P < 0.05, N = 181) showed a positive latitudinal trend in the Brazilian Cerrado region. This result is consistent with diversity trends previously reported in this biome for amphibians [47] and birds [43]. The functional form of the latitudinal trend was different for birds and mammals. Mammal richness presented a positive but non-linear monotonic pattern (Figure 3a), while avian richness showed a positive linear relationship with latitude (Figure 3b).

Bottom Line: We found a positive association between avian and mammal richness and a positive latitudinal trend for both groups in the Brazilian Cerrado.However, an association between avian and mammal diversity remains significant.The approaches introduced here indicate that the prevalence of a significant association among taxa, after considering the environmental determinant, could indicate both the need to incorporate additional processes (e.g. biogeographic and evolutionary history or trophic interactions) and/or the existence of a shared trend in detection biases among taxa and regions.

View Article: PubMed Central - HTML - PubMed

Affiliation: Facultad de Ciencias, Instituto de Ecología y Ciencias Ambientales, Universidad de la República, Uruguay, Iguá 4225 Piso 8 Sur, Montevideo, Uruguay. ctoranza@gmail.com

ABSTRACT

Background: Diversity patterns of different taxa typically covary in space, a phenomenon called cross-taxon congruence. This pattern has been explained by the effect of one taxon diversity on taxon diversity, shared biogeographic histories of different taxa, and/or common responses to environmental conditions. A meta-analysis of the association between environment and diversity patterns found that in 83 out of 85 studies, more than 60% of the spatial variability in species richness was related to variables representing energy, water or their interaction. The role of the environment determining taxa diversity patterns leads us to hypothesize that this would explain the observed cross-taxon congruence. However, recent analyses reported the persistence of cross-taxon congruence when environmental effect was statistically removed. Here we evaluate this hypothesis, analyzing the cross-taxon congruence between birds and mammals in the Brazilian Cerrado, and assess the environmental role on the spatial covariation in diversity patterns.

Results: We found a positive association between avian and mammal richness and a positive latitudinal trend for both groups in the Brazilian Cerrado. Regression analyses indicated an effect of latitude, PET, and mean temperature over both biological groups. In addition, we show that NDVI was only associated with avian diversity; while the annual relative humidity, was only correlated with mammal diversity. We determined the environmental effects on diversity in a path analysis that accounted for 73% and 76% of the spatial variation in avian and mammal richness. However, an association between avian and mammal diversity remains significant. Indeed, the importance of this link between bird and mammal diversity was also supported by a significant association between birds and mammal spatial autoregressive model residuals.

Conclusion: Our study corroborates the main role of environmental conditions on diversity patterns, but suggests that other important mechanisms, which have not been properly evaluated, are involved in the observed cross-taxon congruence. The approaches introduced here indicate that the prevalence of a significant association among taxa, after considering the environmental determinant, could indicate both the need to incorporate additional processes (e.g. biogeographic and evolutionary history or trophic interactions) and/or the existence of a shared trend in detection biases among taxa and regions.

Show MeSH
Related in: MedlinePlus