Limits...
Phylogenies and traits provide distinct insights about the historical and contemporary assembly of aquatic insect communities.

Saito VS, Cianciaruso MV, Siqueira T, Fonseca-Gessner AA, Pavoine S - Ecol Evol (2016)

Bottom Line: Beta niche traits selected a priori - i.e., traits related to environmental variation (e.g., respiration type) - were consistently clustered on the smaller scale, suggesting environmental filtering, while α niche traits - i.e., traits related to resource use (e.g., trophic position) - did not display the expected overdispersion, suggesting a weak role of competition.However, our results likely reflect the co-occurrence of ancient clades due to the stability of stream habitats along the evolutionary scale.Although the phylogenetic structure revealed processes operating at the evolutionary scale, only specific traits explained local processes operating in our communities.

View Article: PubMed Central - PubMed

Affiliation: Programa de Pós-Graduação em Ecologia e Recursos NaturaisUniversidade Federal de São CarlosSão CarlosSPBrazil; Centre d'Ecologie et des Sciences de la Conservation (CESCO UMR7204)Sorbonne Universités, MNHN, CNRS, UPMCCP51, 55-61 rue Buffon75005ParisFrance.

ABSTRACT
The assumption that traits and phylogenies can be used as proxies of species niche has faced criticisms. Evidence suggested that phylogenic relatedness is a weak proxy of trait similarity. Moreover, different processes can select different traits, giving opposing signals in model analyses. To circumvent these criticisms, we separated traits of stream insects based on the concept of α and β niches, which should give clues about assembling pressures expected to act independently of each other. We investigated the congruence between the phylogenetic structure and trait structure of communities using all available traits and all possible combinations of traits (4095 combinations). To account for hierarchical assembling processes, we analyzed patterns on two spatial scales with three pools of genera. Beta niche traits selected a priori - i.e., traits related to environmental variation (e.g., respiration type) - were consistently clustered on the smaller scale, suggesting environmental filtering, while α niche traits - i.e., traits related to resource use (e.g., trophic position) - did not display the expected overdispersion, suggesting a weak role of competition. Using all traits together provided random patterns and the analysis of all possible combinations of traits provided scenarios ranging from strong clustering to overdispersion. Communities were phylogenetically overdispersed, a pattern previously interpreted as phylogenetic limiting similarity. However, our results likely reflect the co-occurrence of ancient clades due to the stability of stream habitats along the evolutionary scale. We advise ecologists to avoid using combinations of all available traits but rather carefully traits based on the objective under consideration. Both trait and phylogenetic approaches should be kept in the ecologist toolbox, but phylogenetic distances should not be used as proxies of traits differences. Although the phylogenetic structure revealed processes operating at the evolutionary scale, only specific traits explained local processes operating in our communities.

No MeSH data available.


Box plots of values of Nearest taxon index (NTI) and Net relatedness index (NRI) on riffle micro‐scale and on stream scale calculated with trait and phylogenetic distances. The pool of genera used in the  model was composed of taxa found in the 13 streams of the Itanhaém river basin. Trait distances were calculated in three different ways: using all traits, using α niche traits and using β niche traits. Median values significantly different from zero according to two‐tailed Wilcoxon test have “*” for P < 0.01.
© Copyright Policy - creativeCommonsBy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4863016&req=5

ece32081-fig-0002: Box plots of values of Nearest taxon index (NTI) and Net relatedness index (NRI) on riffle micro‐scale and on stream scale calculated with trait and phylogenetic distances. The pool of genera used in the model was composed of taxa found in the 13 streams of the Itanhaém river basin. Trait distances were calculated in three different ways: using all traits, using α niche traits and using β niche traits. Median values significantly different from zero according to two‐tailed Wilcoxon test have “*” for P < 0.01.

Mentions: For the riffle micro‐scale, using the river basin pool, NTI and NRI computed with all traits and α niche traits indicated random patterns – i.e., the results were not different from those expected under random assembly. The β niche traits showed clustering in NTI and NRI indicating that local communities are composed of a subset of β niche trait states different from one drawn at random (Wilcoxon test, P < 0.01, except for NTI with incidence data where Wilcoxon test was marginally significant, P < 0.02) (Fig. 2). So, our hypothesis H1 was only partially supported since we found evidences for environmental filtering (clustering in β niche traits) but not of competition (random α niche traits) structuring our communities. In contrast, the phylogenetic structure was significantly overdispersed in both NTI and NRI analyses indicating that co‐occurring genera have distinct evolutionary history (Wilcoxon test, P < 0.01). These results were consistent for both incidence and abundance data (Fig. 2). The results using the stream pool also showed qualitatively similar patterns (Figure S10, Appendix S2). The exception was for phylogenetic NRI (incidence data) that showed clustering; but NTI instead confirmed the overdispersion trend (Figure S10, Appendix S2).


Phylogenies and traits provide distinct insights about the historical and contemporary assembly of aquatic insect communities.

Saito VS, Cianciaruso MV, Siqueira T, Fonseca-Gessner AA, Pavoine S - Ecol Evol (2016)

Box plots of values of Nearest taxon index (NTI) and Net relatedness index (NRI) on riffle micro‐scale and on stream scale calculated with trait and phylogenetic distances. The pool of genera used in the  model was composed of taxa found in the 13 streams of the Itanhaém river basin. Trait distances were calculated in three different ways: using all traits, using α niche traits and using β niche traits. Median values significantly different from zero according to two‐tailed Wilcoxon test have “*” for P < 0.01.
© Copyright Policy - creativeCommonsBy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4863016&req=5

ece32081-fig-0002: Box plots of values of Nearest taxon index (NTI) and Net relatedness index (NRI) on riffle micro‐scale and on stream scale calculated with trait and phylogenetic distances. The pool of genera used in the model was composed of taxa found in the 13 streams of the Itanhaém river basin. Trait distances were calculated in three different ways: using all traits, using α niche traits and using β niche traits. Median values significantly different from zero according to two‐tailed Wilcoxon test have “*” for P < 0.01.
Mentions: For the riffle micro‐scale, using the river basin pool, NTI and NRI computed with all traits and α niche traits indicated random patterns – i.e., the results were not different from those expected under random assembly. The β niche traits showed clustering in NTI and NRI indicating that local communities are composed of a subset of β niche trait states different from one drawn at random (Wilcoxon test, P < 0.01, except for NTI with incidence data where Wilcoxon test was marginally significant, P < 0.02) (Fig. 2). So, our hypothesis H1 was only partially supported since we found evidences for environmental filtering (clustering in β niche traits) but not of competition (random α niche traits) structuring our communities. In contrast, the phylogenetic structure was significantly overdispersed in both NTI and NRI analyses indicating that co‐occurring genera have distinct evolutionary history (Wilcoxon test, P < 0.01). These results were consistent for both incidence and abundance data (Fig. 2). The results using the stream pool also showed qualitatively similar patterns (Figure S10, Appendix S2). The exception was for phylogenetic NRI (incidence data) that showed clustering; but NTI instead confirmed the overdispersion trend (Figure S10, Appendix S2).

Bottom Line: Beta niche traits selected a priori - i.e., traits related to environmental variation (e.g., respiration type) - were consistently clustered on the smaller scale, suggesting environmental filtering, while α niche traits - i.e., traits related to resource use (e.g., trophic position) - did not display the expected overdispersion, suggesting a weak role of competition.However, our results likely reflect the co-occurrence of ancient clades due to the stability of stream habitats along the evolutionary scale.Although the phylogenetic structure revealed processes operating at the evolutionary scale, only specific traits explained local processes operating in our communities.

View Article: PubMed Central - PubMed

Affiliation: Programa de Pós-Graduação em Ecologia e Recursos NaturaisUniversidade Federal de São CarlosSão CarlosSPBrazil; Centre d'Ecologie et des Sciences de la Conservation (CESCO UMR7204)Sorbonne Universités, MNHN, CNRS, UPMCCP51, 55-61 rue Buffon75005ParisFrance.

ABSTRACT
The assumption that traits and phylogenies can be used as proxies of species niche has faced criticisms. Evidence suggested that phylogenic relatedness is a weak proxy of trait similarity. Moreover, different processes can select different traits, giving opposing signals in model analyses. To circumvent these criticisms, we separated traits of stream insects based on the concept of α and β niches, which should give clues about assembling pressures expected to act independently of each other. We investigated the congruence between the phylogenetic structure and trait structure of communities using all available traits and all possible combinations of traits (4095 combinations). To account for hierarchical assembling processes, we analyzed patterns on two spatial scales with three pools of genera. Beta niche traits selected a priori - i.e., traits related to environmental variation (e.g., respiration type) - were consistently clustered on the smaller scale, suggesting environmental filtering, while α niche traits - i.e., traits related to resource use (e.g., trophic position) - did not display the expected overdispersion, suggesting a weak role of competition. Using all traits together provided random patterns and the analysis of all possible combinations of traits provided scenarios ranging from strong clustering to overdispersion. Communities were phylogenetically overdispersed, a pattern previously interpreted as phylogenetic limiting similarity. However, our results likely reflect the co-occurrence of ancient clades due to the stability of stream habitats along the evolutionary scale. We advise ecologists to avoid using combinations of all available traits but rather carefully traits based on the objective under consideration. Both trait and phylogenetic approaches should be kept in the ecologist toolbox, but phylogenetic distances should not be used as proxies of traits differences. Although the phylogenetic structure revealed processes operating at the evolutionary scale, only specific traits explained local processes operating in our communities.

No MeSH data available.