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1. Climatic niche comparisons of eastern North American and eastern Asian disjunct plant genera

   https://doi.org/10.1111/geb.13504  

   Melton, Anthony E. ; Clinton, Matthew H. ; Wasoff, Donald N. ; Lu, Limin ; Hu, Haihua ; Chen, Zhiduan ; Ma, Keping ; Soltis, Douglas E. ; Soltis, Pamela S. ( April 2022 , Global Ecology and Biogeography)

   While the floras of eastern Asia (EA) and eastern North America (ENA) share numerous genera, they have drastically different species richness. Despite an overall similarity in the quality of their temperate climates, the climate of EA is more spatially heterogeneous than that of ENA. Spatial environmental heterogeneity has been found to play a key role in influencing species richness in some regions. Here, we tested the following hypotheses: (a) EA species will occupy larger climatic niches than their ENA congeners, (b) congeners of EA‐ENA disjunct genera will occupy statistically equivalent climatic niches, and (c) congeners of EA‐ENA disjunct genera will occupy more similar climatic niches than expected by their respective physiographic context.

   North America and Asia.

   Present.

   Seed plants.

   Predictions generated by ecological niche models (ENMs) were compared for 88 species across 31 EA‐ENA disjunct genera. ENM predictions were assessed for geographic and ecological breadth. Tests for niche equivalency and similarity were performed for congeneric species pairs to determine if species of disjunct genera have experienced niche conservatism or divergence.

   EA species tend to occupy greater amounts of climatic niche space than their close relatives in ENA. Over two‐thirds of the conducted niche comparisons show that EA‐ENA congeners either occupy equivalent climatic niche space within these broader climatic regimes or occupy non‐equivalent niches that are as similar as expected given their physiographic contexts.

   EA species tend to occupy larger climatic niches, and congeners of EA‐ENA disjunct genera tend to occupy equivalent/similar niche space within their respective distributions, with differences in occupied niches possibly due to their respective physiographic contexts, highlighting how niche‐neutral processes and niche conservatism may affect the distributions of disjunct species.

    

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2. Phylogenomics, biogeography, and evolution of morphology and ecological niche of the eastern Asian–eastern North American Nyssa (Nyssaceae)

   https://doi.org/10.1111/jse.12599  

   Zhou, Wenbin ; Xiang, Qiu‐Yun ; Wen, Jun ( June 2020 , Journal of Systematics and Evolution)

   Nyssa(Nyssaceae, Cornales) represents a classical example of the well‐known eastern Asian–eastern North American floristic disjunction. The genus consists of three species in eastern Asia, four species in eastern North America, and one species in Central America. Species of the genus are ecologically important trees in eastern North American and eastern Asian forests. The distribution of living species and a rich fossil record of the genus make it an excellent model for understanding the origin and evolution of the eastern Asian–eastern North American floristic disjunction. However, despite the small number of species, relationships within the genus have remained unclear and have not been elucidated using a molecular approach. Here, we integrate data from 48 nuclear genes, fossils, morphology, and ecological niche to resolve species relationships, elucidate its biogeographical history, and investigate the evolution of morphology and ecological niches, aiming at a better understanding of the well‐known EA–ENA floristic disjunction. Results showed that the Central American (CAM)Nyssa talamancanawas sister to the remaining species, which were divided among three, rapidly diversified subclades. Estimated divergence times and biogeographical history suggested thatNyssahad an ancestral range in Eurasia and western North America in the late Paleocene. The rapid diversification occurred in the early Eocene, followed by multiple dispersals between and within the Erasian and North American continents. The genus experienced two major episodes of extinction in the early Oligocene and end of Neogene, respectively. The Central AmericanN. talamancanarepresents a relic lineage of the boreotropical flora in the Paleocene/Eocene boundary that once diversified in western North America. The results supported the importance of both the North Atlantic land bridge and the Bering land bridge (BLB) for the Paleogene dispersals ofNyssaand the Neogene dispersals, respectively, as well as the role of Central America as refugia of the Paleogene flora. The total‐evidence‐based dated phylogeny suggested that the pattern of macroevolution ofNyssacoincided with paleoclimatic changes. We found a number of evolutionary changes in morphology (including wood anatomy and leaf traits) and ecological niches (precipitation and temperature) between the EA–ENA disjunct, supporting the ecological selection driving trait evolutions after geographic isolation. We also demonstrated challenges in phylogenomic studies of lineages with rapid diversification histories. The concatenation of gene data can lead to inference of strongly supported relationships incongruent with the species tree. However, conflicts in gene genealogies did not seem to impose a strong effect on divergence time dating in our case. Furthermore, we demonstrated that rapid diversification events may not be recovered in the divergence time dating analysis using BEAST if critical fossil constraints of the relevant nodes are not available. Our study provides an example of complex bidirectional exchanges of plants between Eurasia and North America in the Paleogene, but “out of Asia” migrations in the Neogene, to explain the present disjunct distribution ofNyssain EA and ENA.

    

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3. Passerine sister clade comparisons reveal variable macroevolutionary outcomes of interhemispheric dispersal

   https://doi.org/10.1093/jeb/voad001  

   Imfeld, Tyler S. ; Barker, F. Keith ( December 2023 , Journal of Evolutionary Biology)

   Dispersal events offer a unique window into macroevolutionary processes, especially with respect to the effects of competition on diversification. Empirical studies testing alternative predictions of competitive effects are often limited in either geographic or phylogenetic scale. Here, we tested some of these hypotheses by comparing an assemblage of 16 oscine passerine clades, representing independent dispersal events into the Western Hemisphere, to their sister clades in the Eastern Hemisphere. We also compared the diversity of this assemblage of clades to an older, incumbent passerine clade in the Western Hemisphere, the suboscines. Specifically, we tested for ecological opportunity and incumbency-mediated constraints by analysis of clade-specific morphological disparities and rates of evolution relative to dispersal history. While there was no consistent outcome of oscine dispersal and macroevolution in the Western Hemisphere relative to their Eastern Hemisphere sister groups, most clades supported a role for ecological opportunity or incumbency effects, and such effects were better explained by differences in species accumulation than by differences in rates of trait evolution or colonization timing. This general pattern was not evident when comparing the entire oscine assemblage of the Western Hemisphere to the incumbent suboscine radiation; oscines and suboscines occupy comparable regions of functional trait diversity and, despite higher rates of trait evolution in oscines, these observations were consistent with simulated null expectations. This result suggests that oscine and suboscine assemblages may have evolved in relative isolation for a significant fraction of their history.

    

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4. Global biogeography and diversification of a group of brown seaweeds (Phaeophyceae) driven by clade‐specific evolutionary processes

   https://doi.org/10.1111/jbi.14047  

   Vieira, Christophe ; Steen, Frédérique ; D’hondt, Sofie ; Bafort, Quinten ; Tyberghein, Lennert ; Fernandez‐García, Cindy ; Wysor, Brian ; Tronholm, Ana ; Mattio, Lydiane ; Payri, Claude ; et al ( January 2021 , Journal of Biogeography)

   Historical processes that shaped current diversity patterns of seaweeds remain poorly understood. Using Dictyotales, a globally distributed order of brown seaweeds as a model, we test if historical biogeographical and diversification patterns are comparable across clades. Dictyotales contain some 22 genera, three of which,Dictyota,LobophoraandPadina, are exceptionally diverse. Specifically, we test whether the evolutionary processes that shaped the latitudinal diversity patterns in these clades are in line with the tropical conservatism, out‐of‐the‐tropics or diversification rate hypotheses.

   Global coastal benthic marine environments.

   Dictyotales (Phaeophyceae).

   Species diversity was inferred using DNA‐based species delineation, addressing cryptic diversity and circumventing taxonomic problems. A six‐gene time‐calibrated phylogeny, distribution data of 3,755 specimens and probabilistic modelling of geographical range evolution were used to infer historical biogeographical patterns. The phylogeny was tested against different trait‐dependent models to compare diversification rates for different geographical units as well as different thermal affinities.

   Our results indicate that Dictyotales originated in the Middle Jurassic and reach a current peak of species diversity in the Central Indo‐Pacific. Ancestral range estimation points to a southern hemisphere origin of Dictyotales corresponding to the tropical southern Tethys Sea. Our results demonstrate that diversification rates were generally higher in tropical regions, but increased diversification rates in different clades are driven by different processes. Our results suggest that three major clades underwent a major diversification burst in the early Cenozoic, withDictyotaandPadinaexpanding their distribution into temperate regions whileLobophoraretained a predominantly tropical niche.

   Our results are consistent with both the tropical conservatism hypothesis, in which clades originate and remain in the tropics (Lobophora), and the out‐of‐the‐tropics scenario, where taxa originate and expand towards the temperate regions while preserving their presence in the tropics (Dictyota,Padina).

    

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5. Future Changes of the Eddy Moisture Convergence in Winter Over Coastal Lands in Eastern North America and East Asia

   https://doi.org/10.1029/2022JD037149  

   Liang, Wengui ; Zhang, Minghua ( August 2022 , Journal of Geophysical Research: Atmospheres)

   Previous studies have shown that increasing moisture convergence by transient eddies will cause winter precipitation increase in the future over the coastal lands in Eastern North America (ENA) and East Asia (EA). Using moisture budget and composite analyses, we investigate the physical processes responsible for the change of eddy moisture convergence and compare them between the two regions. We find that in addition to the “wet get wetter and dry get drier” (“WWDD”) thermodynamic effect, changes in eddy moisture advection cause enhanced eddy moisture convergence north of 30°N and divergence to the south, with magnitudes comparable to the “WWDD” effect in these regions. The north‐south dipole pattern is reflected in the precipitation change of drying over the southern coastal lands in the future climate. It is caused by enhanced downgradient eddy moisture transport in the north and upgradient eddy moisture transport in the south, which is explained by the locations of the maximum magnitude of eddy relative humidity in conjunction with increase of mean saturation specific humidity. The eddy dynamic intensities associated with extreme precipitation events are found to increase in the future, contributing to the increase of eddy moisture convergence, but it plays a secondary role. The strong similarities of the underlying processes of eddy moisture change between ENA and EA suggest robust response of the spatially varying role of eddies in impacting future change of regional precipitation in ENA and EA.

    

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