Geographic patterns and environmental correlates of phylogenetic relatedness and diversity for freshwater fish assemblages in North America

The tropical niche conservatism hypothesis suggests that most groups should be most phylogenetically clustered in cold, dry environments. This idea has been well-tested in plants and some animal groups, but not for fishes. We assess the geographic patterns of freshwater fish phylogenetic structure and investigate the relationships between these patterns and environmental variables across North America and within two biogeographic realms. Phylogenetic relatedness and diversity of 360 freshwater fish assemblages across North America were quantified with three metrics based on a well-dated phylogeny, and were related to 15 environmental variables using correlation and regression analyses. Geographically, the data were analyzed for North America as well as for separate biogeographic realms. We found that cold temperatures are the strongest determinant of phylogenetic clustering overall. However, in the arid west, clustering is most pronounced in the driest regions. In eastern North America, phylogenetic clustering increases at higher latitudes, while the reverse is true in western North America. The strongest phylogenetic clustering for freshwater fish assemblages on the continent is found in the most arid, rather than the coldest, climate in North America. Our results highlight that patterns of phylogenetic structure of freshwater fishes in North America are driven by both ecological and evolutionary processes that differ regionally.     

Phylogenetic niche conservatism, phylogenetic signal and the relationship between phylogenetic relatedness and ecological similarity among species

Ecologists are increasingly adopting an evolutionary perspective, and in recent years, the idea that closely related species are ecologically similar has become widespread. In this regard, phylogenetic signal must be distinguished from phylogenetic niche conservatism. Phylogenetic niche conservatism results when closely related species are more ecologically similar that would be expected based on their phylogenetic relationships; its occurrence suggests that some process is constraining divergence among closely related species. In contrast, phylogenetic signal refers to the situation in which ecological similarity between species is related to phylogenetic relatedness; this is the expected outcome of Brownian motion divergence and thus is necessary, but not sufficient, evidence for the existence of phylogenetic niche conservatism. Although many workers consider phylogenetic niche conservatism to be common, a review of case studies indicates that ecological and phylogenetic similarities often are not related. Consequently, ecologists should not assume that phylogenetic niche conservatism exists, but rather should empirically examine the extent to which it occurs.     

Global phylogenetic structure of the hyperdiverse ant genus Pheidole reveals the repeated evolution of macroecological patterns

Adaptive radiations are of particular interest owing to what they reveal about the ecological and evolutionary regulation of biodiversity. This applies to localized island radiations such as Darwin''s finches, and also to rapid radiations occurring on a global scale. Here we analyse the macroevolution and macroecology of Pheidole, a famously hyperdiverse and ecologically dominant ant genus. We generate and analyse four novel datasets: (i) a robust global phylogeny including 285 Pheidole species, (ii) a global database on regional Pheidole richness in 365 political areas summarizing over 97 000 individual records from more than 6500 studies, (iii) a global database of Pheidole richness from 3796 local communities and (iv) a database of Pheidole body sizes across species. Analysis of the potential climate drivers of richness revealed that the patterns are statistically very similar across different biogeographic regions, with both regional and local richness associated with the same coefficients of temperature and precipitation. This similarity occurs even though phylogenetic analysis shows that Pheidole reached dominance in communities through serial localized radiations into different biomes within different continents and islands. Pheidole body size distributions have likewise converged across geographical regions. We propose these cases of convergence indicate that the global radiation of Pheidole is structured by deterministic factors regulating diversification and diversity.     

Climatic correlates of phylogenetic relatedness of woody angiosperms in forest communities along a tropical elevational gradient in South America

Aims This study assesses the relationship between phylogenetic relatedness of angiosperm tree species and climatic variables in local forests distributed along a tropical elevational gradient in South America. In particular, this paper addresses two questions: Is phylogenetic relatedness of plant species in communities related to temperature variables more strongly than to water variables for tropical elevational gradients? Is phylogenetic relatedness of plant species in communities driven by extreme climatic conditions (e.g. minimum temperature (MT) and water deficit) more strongly than by climatic seasonal variability (e.g. temperature seasonality and precipitation seasonality)?Methods I used a set of 34 angiosperm woody plant assemblages along an elevational gradient in the Andes within less than 5 degrees of the equator. Phylogenetic relatedness was quantified as net relatedness index (NRI) and nearest taxon index (NTI) and was related to major climatic variables. Correlation analysis and structure equation modeling approach were used to assess the relationships between phylogenetic relatedness and climatic variables.Important findings Phylogenetic relatedness of angiosperm woody species in the local forest communities is more strongly associated with temperature-related variables than with water-related variables, is positively correlated with mean annual temperature (MAT) and MT, and is related with extreme cold temperature more strongly than with seasonal temperature variability. NTI was related with elevation, MAT and MT more strongly than was NRI. Niche convergence, rather than niche conservatism, has played a primary role in driving community assembly in local forests along the tropical elevational gradient examined. Negative correlations of phylogenetic relatedness with elevation and higher correlations of phylogenetic relatedness with elevation and temperature for NTI than for NRI indicate that evolution of cold tolerance at high elevations in tropical regions primarily occurred at recent (terminal) phylogenetic nodes widely distributed among major clades.     

Global patterns in the phylogenetic structure of island mammal assemblages

Assemblage-level phylogenies carry the signature of ecological and evolutionary processes, which may provide useful information on modes of assemblage formation. We present a global-scale analysis of the emergent phylogenetic properties of mammal assemblages on islands, in which we compared the structure of 595 island assemblages with null models constructed under four alternative definitions of regional source pools. Although most assemblages had a structure indistinguishable from random samples, for some mammal taxa, up to 40% of island assemblages were phylogenetically overdispersed. This suggests that in at least some cases, the processes that shape island faunas are not independent of phylogeny. Furthermore, measures of phylogenetic structure were associated in some cases with island geographical features (size, maximum elevation and habitat diversity). Our results suggest that part of the signal of assemblage formation processes is detectable in the phylogenies of contemporary island mammal faunas, though much is obscured by the complexity of these processes.     

Ecological niche models of invasive seaweeds

Ecological niche models (ENMs) are commonly used to calculate habitat suitability from species’ occurrence and macroecological data. In invasive species biology, ENMs can be applied to anticipate whether invasive species are likely to establish in an area, to identify critical routes and arrival points, to build risk maps and to predict the extent of potential spread following an introduction. Most studies using ENMs focus on terrestrial organisms and applications in the marine realm are still relatively rare. Here, we review some common methods to build ENMs and their application in seaweed invasion biology. We summarize methods and concepts involved in the development of niche models, show examples of how they have been applied in studies on algae and discuss the application of ENMs in invasive algae research and to predict effects of climate change on seaweed distributions.     

Contrasting patterns of phylogenetic assemblage structure along the elevational gradient for major hummingbird clades

Aim We evaluated the hypothesis that, given niche conservatism, relatedness of co‐occurring hummingbird species of a given clade will increase at greater distances from the elevation where it originated. We also used prior knowledge of flight biomechanics and feeding specialization of hummingbird species (family Trochilidae) to evaluate which environmental variables were important predictors of changes in phylogenetic structure for each hummingbird clade. Location Ecuador. Methods We compiled species lists for 189 local hummingbird assemblages across major environmental gradients in Ecuador from a variety of published and non‐published sources. For the entire family and each of the major hummingbird clades (hermits, emeralds, mangoes, coquettes and brilliants) we quantified the phylogenetic structure of each assemblage using the net relatedness index (NRI). This index calculates the standardized mean of all possible pairwise phylogenetic distances between co‐occurring species. We related NRI for each clade to elevation, precipitation and vegetation‐related variables using generalized additive models. Results Our findings support the prediction of an increase in the co‐occurrence of close relatives away from the elevation of origin at the family level and for assemblages of mangoes and brilliants. The opposite pattern was found for assemblages of coquettes and emeralds. For the hermits, variation in phylogenetic structure was not explained by elevation. Clades with high levels of feeding specialization (hermits and brilliants) always included a vegetation‐related variable as an important predictor of change in phylogenetic structure. Main conclusions We found no overall support for the conservatism and zone of origin hypotheses. Knowledge of each clade’s natural history proved useful for predicting which environmental variables correlated with phylogenetic structure of local assemblages. Clades with the same elevation of origin appear to have radiated along the elevational gradient in association with different environmental factors.     

Joint effect of phylogenetic relatedness and trait selection on the elevational distribution of Rhododendron species

Congeneric species may coexist at fine spatial scales through niche differentiation, however, the magnitude to which the effects of functional traits and phylogenetic relatedness contribute to their distribution along elevational gradients remains understudied. To test the hypothesis that trait and elevational range overlap can affect local speciesʼ coexistence, we first compared phylogenetic relatedness and trait (including morphological traits and leaf elements) divergence among closely related species of Rhododendron L. on Yulong Mountain, China. We then assessed relationships between the overlap of multiple functional traits and the degree of elevational range overlap among species pairs in a phylogenetic context. We found that phylogeny was a good predictor for most functional traits, where closely related species showed higher trait similarity and occupied different elevational niches at our study site. Species pairs of R. subgen. Hymenanthes (Blume) K. Koch showed low elevational range overlap and some species pairs of R. subgen. Rhododendron showed obvious niche differentiation. Trait divergence is greater for species in R. subgen. Rhododendron, and it plays an important role between species pairs with low elevational range overlap. Trait convergent selection takes place between co-occurring closely related species that have high elevational range overlap, which share more functional trait space due to environmental filtering or ecological adaptation in more extreme habitats. Our results highlight the importance of evolutionary history and trait selection for species coexistence at fine ecological scales along environmental gradients.     

Phylogenetic turnover during subtropical forest succession across environmental and phylogenetic scales

Although spatial and temporal patterns of phylogenetic community structure during succession are inherently interlinked and assembly processes vary with environmental and phylogenetic scales, successional studies of community assembly have yet to integrate spatial and temporal components of community structure, while accounting for scaling issues. To gain insight into the processes that generate biodiversity after disturbance, we combine analyses of spatial and temporal phylogenetic turnover across phylogenetic scales, accounting for covariation with environmental differences. We compared phylogenetic turnover, at the species‐ and individual‐level, within and between five successional stages, representing woody plant communities in a subtropical forest chronosequence. We decomposed turnover at different phylogenetic depths and assessed its covariation with between‐plot abiotic differences. Phylogenetic turnover between stages was low relative to species turnover and was not explained by abiotic differences. However, within the late‐successional stages, there was high presence‐/absence‐based turnover (clustering) that occurred deep in the phylogeny and covaried with environmental differentiation. Our results support a deterministic model of community assembly where (i) phylogenetic composition is constrained through successional time, but (ii) toward late succession, species sorting into preferred habitats according to niche traits that are conserved deep in phylogeny, becomes increasingly important.     

Phylogenetic relatedness and plant invader success across two spatial scales

Aim  Successful invaders often possess similar ecological traits that contribute to success in new regions, and thus under niche conservatism, invader success should be phylogenetically clustered. We asked if the degree to which non-native plant species are phylogenetically related is a predictor of invasion success at two spatial scales.
Location  Australia – the whole continent and Royal National Park (south-eastern Australia).
Methods  We used non-native plant species occupancy in Royal National Park, as well as estimated continental occupancy of these species from herbarium records. We then estimated phylogenetic relationships using molecular data from three gene sequences available on GenBank ( matK , rbcL and ITS1 ). We tested for phylogenetic signals in occupancy using Blomberg's K .
Results  Whereas most non-native plants were relatively scarce, there was a strong phylogenetic signal for continental occupancy, driven by the clustering of successful species in Asteraceae, Caryophyllaceae, Poaceae and Solanaceae. However, we failed to detect a phylogenetic signal at the park scale.
Main Conclusions  Our results reveal that at a large spatial scale, invader success is phylogenetically clustered where ecological traits promoting success appear to be shared among close relatives, indicating that phylogenetic relationships can be useful predictors of invasion success at large spatial scales. At a smaller, landscape scale, there was no evidence of phylogenetic clustering of invasion success, and thus, relatedness plays a much reduced role in determining the relative success of invaders.     

华北区域环境梯度上阔叶林构建模式及分布成因

森林群落的构建即多样性维持机制是当今生态学研究的热点问题。然而, 当前群落构建和群落多样性的研究多在间接梯度上进行, 而在水、热等影响物种在区域内定植的关键且直接的环境梯度上研究群落构建和多样性模式则鲜有报道。结合环境因子, 基于物种组成和谱系方法探讨不同群落的分布成因, 有助于解释群落构建过程中的关键问题。该研究基于华北森林群落调查数据和环境数据, 涉及7个省市区的29个以壳斗科、桦木科为优势种的群落, 探讨了直接环境梯度上的群落构建和多样性模式, 同时用典范对应分析研究了不同群落分布的环境解释。结果发现, 相似的群落具有相似的生境偏好, 相似的生境条件会形成物种组成相同或相似的群落。环境热量主导了本区域的谱系关系, 在年平均气温较低的地区, 群落构建主要表现为生境过滤的模式。此外, 随着年降水量的增加, 生境过滤作用逐渐增加。在温度梯度上, 谱系多样性表现为钟形模式, 而降水量的增加能导致谱系多样性的增加。     

Climatic niche evolution in turtles is characterized by phylogenetic conservatism for both aquatic and terrestrial species

Understanding how the climatic niche of species evolved has been a topic of high interest in current theoretical and applied macroecological studies. However, little is known regarding how species traits might influence climatic niche evolution. Here, we evaluated patterns of climatic niche evolution in turtles (tortoises and freshwater turtles) and whether species habitat (terrestrial or aquatic) influences these patterns. We used phylogenetic, climatic and distribution data for 261 species to estimate their climatic niches. Then, we compared whether niche overlap between sister species was higher than between random species pairs and evaluated whether niche optima and rates varied between aquatic and terrestrial species. Sister species had higher values of niche overlap than random species pairs, suggesting phylogenetic climatic niche conservatism in turtles. The climatic niche evolution of the group followed an Ornstein–Uhlenbeck model with different optimum values for aquatic and terrestrial species, but we did not find consistent evidence of differences in their rates of climatic niche evolution. We conclude that phylogenetic climatic niche conservatism occurs among turtle species. Furthermore, terrestrial and aquatic species occupy different climatic niches but these seem to have evolved at similar evolutionary rates, reinforcing the importance of habitat in understanding species climatic niches and their evolution.     

Global patterns of amphibian phylogenetic diversity

Aim Phylogenetic diversity can provide insight into how evolutionary processes may have shaped contemporary patterns of species richness. Here, we aim to test for the influence of phylogenetic history on global patterns of amphibian species richness, and to identify areas where macroevolutionary processes such as diversification and dispersal have left strong signatures on contemporary species richness. Location Global; equal‐area grid cells of approximately 10,000 km². Methods We generated an amphibian global supertree (6111 species) and repeated analyses with the largest available molecular phylogeny (2792 species). We combined each tree with global species distributions to map four indices of phylogenetic diversity. To investigate congruence between global spatial patterns of amphibian species richness and phylogenetic diversity, we selected Faith’s phylogenetic diversity (PD) index and the total taxonomic distinctness (TTD) index, because we found that the variance of the other two indices we examined (average taxonomic distinctness and mean root distance) strongly depended on species richness. We then identified regions with unusually high or low phylogenetic diversity given the underlying level of species richness by using the residuals from the global relationship of species richness and phylogenetic diversity. Results Phylogenetic diversity as measured by either Faith’s PD or TTD was strongly correlated with species richness globally, while the other two indices showed very different patterns. When either Faith’s PD or TTD was tested against species richness, residuals were strongly spatially structured. Areas with unusually low phylogenetic diversity for their associated species richness were mostly on islands, indicating large radiations of few lineages that have successfully colonized these archipelagos. Areas with unusually high phylogenetic diversity were located around biogeographic contact zones in Central America and southern China, and seem to have experienced high immigration or in situ diversification rates, combined with local persistence of old lineages. Main conclusions We show spatial structure in the residuals of the relationship between species richness and phylogenetic diversity, which together with the positive relationship itself indicates strong signatures of evolutionary history on contemporary global patterns of amphibian species richness. Areas with unusually low and high phylogenetic diversity for their associated richness demonstrate the importance of biogeographic barriers to dispersal, colonization and diversification processes.     

Evolutionary constraints on regional faunas: whom, but not how many

The latitudinal diversity gradient has been hypothesized to reflect past evolutionary dynamics driven by climatic niche conservation during cladogenesis, i.e. the tropical conservatism hypothesis. Here we show that the species diversity of treefrogs (Hylidae) across the western hemisphere is actually independent of evolutionary niche dynamics. We evaluated three key predictions of the tropical conservatism hypothesis that relate to the relationships between climate, species richness and the phylogenetic structure of regional treefrog faunas across the continental Americas. Species composition was dependent on the inability of some lineages to evolve cold tolerance, but the actual number of species in a region was strongly predicted by precipitation, not temperature. Moreover, phylogenetic structure was independent of precipitation. Thus, species in low-richness areas were no more closely related than species in highly diverse regions. These results provide no support for the tropical conservatism hypothesis. Instead, they show that regional species composition and richness are constrained by different climatic components, demonstrating that global biodiversity gradients can be independent of niche stasis during cladogenesis.