AIM: Endemic species are hypothesized to particularly occur in areas with relatively stable climates during the Quaternary glacial‐interglacial oscillations (orbitally forced species' range dynamics ...hypothesis). This hypothesis has received support in global studies and studies from regions highly affected by glaciations. Here, we test its applicability to Chinese endemic species, thereby testing it in a region that was relatively mildly affected by glaciations. LOCATION: China. METHODS: We tested for associations between endemic species richness and Quaternary climate change, current climate and topography. Changes in mean annual temperature (MAT) and annual precipitation (MAP) between the Last Glacial Maximum and present were used to describe Quaternary climate change. We used simultaneous autoregressive (SAR) models to account for spatial autocorrelation in predictors, and Random Forest modelling to deal with non‐linear relationships and better handle multicollinearity among predictor variables. To get a deeper understanding of the mechanisms involved we also performed analyses based on growth‐form (woody versus herbaceous plants) and species age (palaeo‐ and neoendemics). RESULTS: Single‐predictor SAR models showed that glacial‐interglacial MAT velocity always has higher explanatory power than current climate (with a pseudo r² difference of 0.581–0.604 between the best palaeoclimate and current climate predictors for models for all endemic plants). Model selection on multivariate SAR models (based on Akaike weights) and Random Forest modelling (based on correlations between predicted and observed species richness) always included at least one variable representing Quaternary climate change as well as one or more current climate variables. Quaternary climate‐change variables were generally of similar strength to the current climate predictors. Notably, the summed Akaike weight across all models in the relevant model set was always 1 for glacial‐interglacial MAT velocity. There were no clear differences with respect to growth forms or species age in the estimated importance of Quaternary climate change. MAIN CONCLUSIONS: The consistent association between long‐term climatic stability and high plant endemism in China provides strong evidence for the importance of Quaternary glacial‐interglacial climate changes in shaping the distribution of endemic species, even in regions relatively mildly affected by glaciations. Hence, even moderate climate changes may have strong, long‐term effects on species diversity patterns.
Acantholeberis smirnovi Paggi & Herrera-Martinez, 2020 (Cladocera: Acantholeberidae) was recently described from Andean habitats in South America. The presence of a population on the eastern coast of ...the continent brought the hypothesis of a new Neotropical species different from A. smirnovi. This hypothesis was confirmed from morphological, ecological and biogeographic evidence. Acantholeberis accolismaris Sousa, Elmoor-Loureiro & Álvarez-Silva sp. nov. differs from A. smirnovi in the morphology of the head, the valves and the limbs (especially the second and third limbs). Species of Acantholeberis are adapted to live in acid water bodies, with A. accolismaris sp. nov. presenting the same ecological requirements. However, the new species is adapted to live in temporary ponds near the Atlantic Ocean in Brazil in altitudes ranging between 4 and 15 meters above sea level. Considering that Acantholeberidae is an ancient taxon with a pre-Mesozoic origin, geological and environmental changes may have been relevant to speciation and to the observed biogeographic pattern of species of Acantholeberis in Neotropics.
The Equilibrium Theory of Island Biogeography postulates that larger and closer islands support higher biodiversity through the dynamic balance of colonization and extinction processes. The negative ...diversity–isolation (i.e. the distance to the mainland) relationship is derived based on the assumption that the mainland is the only source pool for island biotas. However, nearby islands could also act as species sources for focal islands via a source effect. In this study, we move a further step and hypothesize that nearby islands may reduce bird colonizers of the focal island and diminish its biodiversity, resulting in a negative target effect.
To test our hypothesis, we assessed the effects of island area and isolation (metrics considering both the mainland and nearby islands) on taxonomic (i.e. species richness), functional and phylogenetic diversity of terrestrial breeding birds on 42 islands in the largest archipelago of China, the Zhoushan Archipelago. Furthermore, we compared the predictive power of the distance to the large island under a set of relative area thresholds and the relative area of nearby islands on species richness under a set of distance thresholds to explore the role of nearby islands as a source and/or target island.
We found that island area had a positive effect on species richness, phylogenetic diversity and functional diversity, while the distance to the mainland had a negative effect only on species richness. Species richness on the focal island increased with increasing distance to the nearest larger island, indicating the negative target effect. Furthermore, the negative target effect depended on the area of nearby islands relative to the area of the focal island.
Our finding of the negative target effect suggests islands located between the mainland and the focal island can be not only sources or stepping stones, but also colonization targets. This result demonstrates the importance of considering multiple geographical attributes of islands in island biogeographic studies, especially the characteristics related to source and/or target effects.
摘要
岛屿生物地理学平衡理论 (Equilibrium Theory of Island Biogeography) 提出的迁入‐灭绝动态平衡 (colonization‐extinction dynamic) 认为面积更大、隔离度更低的岛屿生物多样性将会更高。大陆通常被认为是岛屿生物的主要源, 因此存在着负的物种数‐大陆距离关系。然而主岛 (focal island) 邻近的其他岛屿同样可能是潜在的物种源 (colonization source)。本研究进一步假设, 邻近岛屿既可以是源, 也可以是拓殖目标 (colonization target)。因此, 邻近岛屿可能吸引主岛的潜在拓殖种群, 降低目标岛屿的迁入率, 进而减少其生物多样性, 我们将其称之为负目标效应 (negative target effect)。
为了验证这一假设, 我们在中国最大的群岛 (浙江舟山群岛), 选取了面积和隔离度尽可能多样的42个岛屿开展鸟类物种调查, 并评估了各个岛屿地理属性 (包括岛屿面积、大陆距离和邻近岛屿相关的隔离度指标) 对鸟类的物种丰富度、功能多样性和系统发育多样性的影响。此外, 我们还比较了不同相对面积阈值下最近大岛距离和不同距离阈值下周边岛屿相对面积对物种丰富度的预测能力, 以探讨邻近岛屿作为源或目标时对岛屿物种丰富度的影响。
研究发现, 岛屿面积对物种丰富度、系统发育多样性和功能多样性有正影响, 而大陆距离只对物种丰富度有负影响。岛屿鸟类丰富度随着与最近大岛距离的增加而增加, 说明邻近岛屿表现出了负目标效应, 而非源效应。我们发现负目标效应受到邻近岛屿相对面积的影响。
负目标效应的发现表明邻近岛屿不仅仅可以作为物种源或是踏脚石 (stepping stone), 也可能是拓殖目标。这说明在岛屿生物地理学研究中考虑多重岛屿地理属性具有重要意义, 特别是那些有关源效应或目标效应的岛屿属性。
Nearby large islands can attract bird species from a focal island and diminish the focal island's biodiversity. We define this phenomenon as the negative target effect, a complement to the (positive) target effect that is widely used in island biogeography.
Abstract
Natricine snakes are geographically widespread, species rich (with ~250 extant species) and both morphologically and ecologically diverse. We present a multilocus DNA sequence phylogeny for ...249 natricine specimens representing 189 named species, including 69 specimens and 21 species not previously sampled. Our inferred Bayesian and maximum likelihood trees form the basis for evaluations of genus-level classification, historical biogeography, lineage diversification, and dietary, habit and reproductive-mode diversity and evolution, although several, mostly deeper, relationships remain poorly resolved. The optimal trees support natricine origins in Asia, with dispersals to Australo-Melanesia, sub-Saharan Africa (including Seychelles Archipelago, excluding Aldabra), Europe and North Africa and into North and Central America. Viviparity appears to have evolved independently three times in Natricinae but was not significantly associated with an aquatic habit. We found limited associations between habit and diet categories. We propose generic reallocations for four natricine species and highlight other points of uncertainty in natricine classification.
Squamates first appeared in Europe in the Middle Jurassic. They were lizards that already included some crown-group members. Faunas of the Late Jurassic and Early Cretaceous were more or less a ...continuation of the Middle Jurassic assemblage. The early Late Cretaceous was characterised by a peculiar fauna of marine pythonomorphs, while terrestrial forms were rare. In the subsequent levels of the Late Cretaceous, marine forms were mainly mosasaurids; terrestrial assemblages heralding modern ones began to take form during the Campanian–Maastrichtian. The Cretaceous–Tertiary event did not strongly affect squamates in Europe. After poor Paleocene faunas, a big wave of dispersals reached Europe during a marked rise in temperature at the beginning of the Eocene (MP 7). The Eocene fauna was rich, diverse and of tropical type. In western Europe, a sharp extinction event (‘Grande Coupure’) eliminated most squamates at the end of the Eocene, but its impact in central and eastern Europe is unknown. The Oligocene fauna was transitional between the ‘old’ Eocene and the modern Miocene faunas. By the late early Miocene (MN 3–MN 4), the fauna markedly changed when an important wave of dispersals entered Europe during a climatic optimum. From the late middle Miocene onward, the temperature has dropped. As a consequence, faunas became less rich and regionalisation occurred. Numerous extinctions and withdrawals took place during the late Pliocene and early Pleistocene, leaving an impoverished fauna in Europe.
Aim
Understanding the factors driving the diversity of alien and native species on islands is crucial for predicting the spread of alien species and for proposing management practices to protect the ...unique native biodiversity that often occurs in insular ecosystems. The main objective of this study was to evaluate whether native and alien plant species respond similarly to natural biogeographic and human‐related drivers.
Location
Lesser Antilles, Caribbean.
Methods
We compiled a dataset with the verified status of native and alien plant species occurring on 15 islands across the Lesser Antilles. We assessed the relationship of native and alien plant species richness and identified the biogeographic and socio‐economic variables that best explain the diversity patterns of both alien and native species on these islands by combining correlation analysis and generalized linear models.
Results
The final dataset comprises a total of 2,438 plant species with 1,825 native species and 613 alien species. For the 15 islands analysed, native and alien species richness is strongly and positively correlated, but different variables explained their diversity patterns. We found that biogeographic drivers such as island area, elevation and distance to the mainland best explain patterns of native species richness. On the other hand, alien species richness was well predicted by a combination of geographic and socio‐economic variables, with per capita gross domestic product (GDP) and island area having the strongest effect. Species composition of alien floras is also significantly influenced by the historical colonial identity of these islands.
Main conclusions
While native species are clearly associated with biogeographic variables, alien species are strongly influenced by variables related to human activities and therefore anthropogenic disturbance processes. Modification of natural areas by human activities can result in high alien species richness even on islands with high native species richness.
Paramecium (Ciliophora, Oligohymenophorea) is a good model to study ciliate biogeography. Extensive sampling mainly in northern hemisphere has led to 16 valid morphological species description thus ...far. However, a majority of hard-to-reach regions, including South East Asia, are underinvestigated. Our study combined traditional morphological and molecular approaches to reveal the biodiversity of Paramecium in Thailand from more than 110 samples collected in 10 provinces. Representatives of seven morphological species were identified from our collection, including the rare species, such as P. gigas and P. jenningsi. Additionally, we detected five different sibling species of the P. aurelia complex, described a new cryptic species P. hiwatashii n. sp. phylogenetically related to P. caudatum, and discovered a potentially new genetic species of the P. bursaria species complex. We also documented a variety of bacterial cytoplasmic symbionts from at least nine monoclonal cultures of Paramecium.
Abstract
Aim
There has been growing interest in non‐cave subterranean habitats and their influence on the evolution of troglomorphic (i.e. ‘subterranean adapted’) species. Studies on the ...diversification of aquatic subterranean organisms in these habitats generally support the ‘subterranean island’ hypothesis, whereby isolated subterranean refuges lead to patterns of short‐range endemism. However, their terrestrial counterparts have received less attention. We aimed to elucidate the applicability of the ‘subterranean island’ hypothesis to terrestrial subterranean fauna through genetic analyses of two widespread troglomorphic cockroach species. To investigate the influence of subterranean biogeography, we also analysed a closely related species that inhabits ‘classic’ cave environments to represent a contrasting biogeographic comparison.
Location
Pilbara region, Western Australia, and the Chillagoe‐Mungana Caves, Queensland (Australia).
Taxa
Cave cockroach species:
Nocticola cockingi
,
Nocticola quartermainei
and
Nocticola australiensis.
Methods
We used DArTseq to generate genome‐wide SNPs in 78 samples, and Sanger sequencing to generate 16S mtDNA data. We then applied various population genomic analyses to characterize the distribution of genetic diversity within the three study species.
Results
We identified distinct genetic clusters within the two Pilbara species; however, there appeared to be a notable lack of discernible population differentiation across large parts of their range (>135 km), opposing the subterranean island hypothesis. The highest level of population differentiation in the three study species was between the two caves in Queensland, ~3 km apart.
Main Conclusions
The Pilbara subterranean habitat appeared to be conducive to gene flow across relatively large distances, contrasting high levels of endemism observed in other subterranean taxa within the region. The disparate patterns of gene flow among the Pilbara and Queensland study species emphasize the significance of differing subterranean habitats on patterns of dispersal and vicariance. These inferences will inform conservation genetic management of these species, and may help elucidate the evolutionary paradox of widespread subterranean fauna.
The geographic distributions of marine species are changing rapidly, with leading range edges following climate poleward, deeper, and in other directions and trailing range edges often contracting in ...similar directions. These shifts have their roots in fine-scale interactions between organisms and their environment-including mosaics and gradients of temperature and oxygen-mediated by physiology, behavior, evolution, dispersal, and species interactions. These shifts reassemble food webs and can have dramatic consequences. Compared with species on land, marine species are more sensitive to changing climate but have a greater capacity for colonization. These differences suggest that species cope with climate change at different spatial scales in the two realms and that range shifts across wide spatial scales are a key mechanism at sea. Additional research is needed to understand how processes interact to promote or constrain range shifts, how the dominant responses vary among species, and how the emergent communities of the future ocean will function.
Pennatulaceans (Octocorallia: Pennatulacea) are among the most dominant octocoral species living in soft bottom communities. Some of them are cosmopolitan and have been recorded in all seas and ...oceans of the world, from shallow waters up to about 6260 m deep. In the present study, we try to find answers to questions about the biogeographical distribution of sea pens including most recently described species. We also evaluate the diversity and faunistic affinities among pennatulaceans of the world’s oceans, and determine the degree of faunistic isolation of the Mediterranean Sea from the Atlantic. Finally, we return to the old debate about the hypothetical oldest diversification center of sea pen lineages.
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