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At the regional scale, our findings suggest that phylogenetic community structure shifts during community assembly to a pattern of dispersion as a consequence of allopatric speciation in recent times but overall, variations in diversification rates did not relate with sea level changes. The shift in phylogenetic community structure among islands toward phylogenetic dispersion emphasizes that marine barriers to dispersal fluctuate in effectiveness through times Rocha and Bowen Table 2 Clade ages reported in previous molecular phylogenetic studies of Chaetodontidae, Pomacentridae, and Labridae. In this context, species richness may increase through diversification up to a stationary state in communities as a function of species-area relationships. Aligned datasets ranged between bp for the Chaetodontidae and bp for the Pomacentridae and reached bp in the Labridae. Nevertheless, this expectation is challenged by recent phylogenetic studies on marine fish supporting that ecological shifts have been rather rare during the diversification of several lineages of coral reef fish as exemplified by the scarcity of trophic shifts Streelman et al.
The three families provided very similar net diversification rates, overlapping with the estimate from the pooled data, suggesting common diversification regimes Table 4 ; Fig. Worth noting, this pattern was remarkably stable across the three islands. Open in a separate window. The present pattern is consistent with this model since most of the lineages exhibiting alternative distribution i. The Dell – Verbally and physically crisp, clear and First, a lineage may become extinct as a consequence of physical perturbations e.
We also considered a time-dependent extension of the Yule model as implemented in APE that allows the user to specify any arbitrary model.
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The relative contribution of each component is determined by a smoothing parameter S whose optimal values are determined through a cross-validation procedure that measures the fit between observed and predicted numbers of substitution in terminal branches according to the model.
Hutchinson ; Pianka ; Anderson et al. Sea levels fluctuations, particularly the last episode of marine highstand between 4 Myr and 5 Myr Fig. Discussion Phylogenetic community structure and spatial scales Initially proposed by Webbthe analysis of phylogenetic community structure is based on the assumption that, because organisms interact via their phenotypes, and because phenotypes are not randomly distributed with respect to phylogeny, we should expect that the phylogenetic composition of a community is partially the product of species interactions Webb et al.
Community assembly and diversification in Indo-Pacific coral reef fishes
Species that live together in a local community do so because they are present in the larger regional species pool and have characteristics that permit their existence at a given locality and their coexistence with other species in the community Webb et al. Since coral reef fish tends to be generalists forming heterospecific feeding schools, several authors opposed to the conventional niche theory, a stationary model of coexistence, which emphasizes the role of stochastic recruitment and mortality in determining local coexistence of species lottery model, Sale; Chesson and Warner ; Warner and Chesson In our study, a decrease in diversification rate, consistent with a niche-based view of diversification, was found in agreement with previous studies Table 1.
By contrast, the neutral model predicts no such decrease in net diversification since speciation and extinction, as stochastic and diversity independent processes, will be constant Hubbell ; Ricklefs Table 6 Summary statistics of community structure from inner reefs and outer slopes sites in Reunion, Madagascar, and French Polynesia according to Appendix 1. In this context, we gathered new phylogenetic data based on the same set of molecular markers for all families and covering all the species in the sampled communities in order to limit bias in our phylogenetic inferences.
Fessler and Westneat paoa This analysis aimed at estimating the influence of large-scale geographic isolation on community assembly likely influenced by historical factors. Nevertheless, the implications for speciation and extinction rates are not trivial.
The tree presented here is very similar to the phylogeny published by Fessler and Westneat excepting the position of C. In this context, several specimens from different sites and islands were sampled for epiwode species and the three mitochondrial markers were sequenced in order to consider biological units and preclude taxonomic bias in the community analyses.
Follow Scoop on Twitter. We examined the phylogenetic community structure and diversification rates in three families and 14 sites within coral reef fish communities from the Indian and Pacific oceans.
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We inferred phylogenetic relationships among species from the families Chaetodontidae, Pomacentridae, and Labridae, being among the most diverse tropical reef fish lineages Bellwood and Hughes ; Mora et al. By contrast, the neutral theory supports that speciation is stochastic and diversity independent.
Giving this result and the notorious difficulties to estimate extinctions with molecular phylogenies Kubo and Iwasa ; Stadler ; Paradiswe focused on a Yule model considering speciation as a proxy for diversification. As a consequence, the observed decrease in diversification rates may be seen as the result of a limited supply of living space as expected in a finite island model.
This is an open access article under the terms of the Creative Commons Attribution Non Commercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes. Community assembly and diversification Communities are the product of biotic and landscapes fluctuations over evolutionary times Ricklefs ; Ricklefs and Schluter Table 4 Parameters estimates for distinct time-dependent models of diversification.
Because ecosystems are dynamic and species permanently adapt to changing paeoa, understanding the evolutionary mechanisms structuring communities is a challenge Ricklefs and Schluter ; Leibold et al. Shifts in phylogenetic community structure, however, raise the question of the ecological mechanisms driving community assembly, and previous authors pointed to the importance of spatial scale in detecting phylogenetic community structure Cavender-Barres pzroa al.
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RNZ – Te Matatini festival ‘better than Recent molecular studies regularly emphasized the presence of cryptic diversity in coral reef fish including in the three selected families McCafferty et al. Several phylogenies have been published during the last decade for these families Westneat and Alfaro ; Fessler and Wesneat ; Cooper et al.
Here, the use of a threshold-based approach confirmed that phylogenetic community structure might not be constant and helped detect nested patterns. Protein-coding regions were aligned manually episodee 16S sequences were first aligned through multiple alignments using Clustal W Thompson et al.
Appendix 1 Sampling records for the species of Chaetodontidae, Pomacentridae, and Labridae included in the present study. Table 3 Results of the Likelihood ratio test of constant rate of substitution.
We then tested several alternative models of epidode fitted by ML.
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A relationship between species range overlap and species divergence times has been recently detected in Pomacentrid fish and Labrid fish as expected following a model of allopatric speciation and evolution of species ranges through major shifts Quenouille et al. Table 1 Summary of the predictions tested in the present study. Phylogenetic relationships within Chaetodontidae among specimens belonging to 33 species and four genera with 46 outgroup taxa.
Coral reefs are among the most diverse and structurally complex ecosystems Sale We first checked for potential departures from a stationary model of diversification through a lineage through time LTT plot analyses Harvey et al. According to the niche theory, competitive exclusion promote resource partitioning and ecological specialization Schlutera trend that may be expected to produce frequent ecological shifts during lineage evolution to foster the filling of the ecological space Losos et al.
Once a tree was computed for each family, a final cladogram based on the topologies inferred for each family was build and a new alignment including a single, randomly picked individual for each species was used for branch length optimization of the final cladogram in maximum likelihood ML using PhyML Guindon and Gascuel Lineages diversify and supply communities with species that arrange themselves in assemblies as a consequence of ecological constraints i.