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9 results for “Tropical niche conservatism”

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dryad36/100

Data from: Marine latitudinal diversity gradients, niche conservatism, and out of the tropics and Arctic: climatic sensitivity of small organisms

<ul> <li>Aim</li> </ul> The latitudinal diversity gradient (LDG) is a consequence of evolutionary and ecological mechanisms acting over long history, and thus is best investigated with organisms that have rich fossil records. However, combined neontological-paleontological investigations are mostly limited to large, shelled invertebrates, which keeps our mechanistic understanding of LDGs in its infancy. This paper aims to describe the modern meiobenthic ostracod LDG and to explore the possible controlling factors and the evolutionary mechanisms of this large-scale biodiversity pattern. <ul> <li>Location</li> </ul> Present-day Western North Atlantic <ul> <li>Taxon</li> </ul> Ostracoda <ul> <li>Methods</li> </ul> We compiled census data from ostracods living in shallow marine environments of the western North Atlantic Ocean. Using these data, we documented the marine LDG with multiple metrics of alpha, beta (nestedness and turnover), and gamma diversity, and we tested whether macroecological patterns could be governed by different environmental factors, including temperature, salinity, dissolved oxygen, pH and primary productivity. We also explored the geologic age distribution of ostracod genera to investigate the evolutionary mechanisms underpinning the LDG. <ul> <li>Results</li> </ul> Our results show that temperature and climatic niche conservatism are important in setting LDGs of these small, poorly-dispersing organisms. We also found evidence for some dispersal-driven spatial dynamics in the ostracod LDG. Compared to patterns observed in marine bivalves, however, dispersal dynamics were weaker and they were bi-directional, rather than following the "out-of-the-tropics" model. <ul> <li>Main Conclusions</li> </ul> Our detailed analyses revealed that meiobenthic organisms, which comprise two-thirds of marine diversity, do not always follow the same rules as larger, better-studied organisms. Our findings suggest that the under-studied majority of biodiversity may be more sensitive to climate than are well-studied, large organisms. This implies that the impacts of ongoing Anthropocene climatic change on marine ecosystems may be much more serious than presently thought.

opencc-zeroDec 2020View details →

dryad36/100

Tropical niche conservatism explains the Eocene migration from India to Southeast Asia in Ochyroceratid spiders

Biological migrations between India and Southeast (SE) Asia provide an ideal system for exploring the effects of geology and climate on species ranges. Geologists have confirmed that the direct collision between India and Eurasia occurred in the Early Eocene, but most migrations occurred between the Indian subcontinent and SE Asia rather than the former and the southern margin of Eurasia. To explain this seemingly paradoxical disconnect between the routes of plate movement and biological migration, we studied the evolutionary history of the tropical spider family Ochyroceratidae based on 101 globally distributed species. We infer a robust dated phylogeny using both transcriptomic data and a dataset of classical markers and relate these to biogeographic and climatic analyses. Our results indicate that the monophyly of Ochyroceratidae is strongly supported, and the divergence times suggest a Cretaceous Gondwanan origin of the family. Reconstructed biogeographic histories support a dispersal event from the Indian subcontinent to islands of SE Asia 55–38 million years ago. Climatic analyses and the fossil record reveal that ochyroceratids are characterized by a high degree of tropical niche conservatism, and that the ancestor of the Indian and SE Asian clades originated in very warm, wet environments. Early Eocene tropical, perhumid climates in India and SE Asia may have facilitated ochyroceratid migration, whereas the dry or seasonal climate extending from the eastern coast of China to Central Asia may have acted as a barrier, preventing dispersal. Our analyses suggest that climate plays a more important role than geology in biological migration from the Indian subcontinent to SE Asia, providing new insights into the Indian–Asian biogeographic link.

opencc-zeroFeb 2020View details →

dryad36/100

Niche conservatism limits the distribution of Medicago in the tropics

The increase in species number from poles to the equator is one of the most fundamental patterns in ecology. Although several hypotheses have been proposed, there is a lack of consensus on the mechanisms underlying this pattern. While most hypotheses provide plausible explanation for high tropical diversity of tropical clades, it is unclear if similar mechanisms drive the diversity of extra-tropical clades. Here, we investigated the environmental drivers influencing the diversity pattern of a Mediterranean plant genus Medicago and dissect their effects across continents and biomes. We compiled a comprehensive dataset on the distribution of all Medicago species and mapped their distribution at the spatial resolution of 100 × 100 km2. We used generalized linear models to quantify the relative effects of environmental factors on the richness patterns of Medicago and its two life forms. Next, using geographically weighted regression, we explored the variation in richness-environment relationship across latitude. We found that Quaternary climate change and environmental energy were important explanatory variables, and their effects were consistent at global, continental and biome scales. However, we found contrasting effect of environmental energy in temperate and tropical regions, with species richness increasing with energy in the temperate and decreasing in the tropics. We also found strong affinity of Medicago species to its ancestral Mediterranean climatic niche. Our results suggest that the spatial variation in Medicago richness patterns may be strongly influenced by heat tolerance as opposed to the tropical clades that depend upon cold tolerance. This dependency on heat tolerance can be attributed to strong niche conservatism exhibited by Medicago species. Our findings provide new insights into the richness-energy hypothesis and suggest that high environmental energy may not necessarily yield high species diversity but may also lower species diversity, especially of extra-tropical clades towards the tropics.

opencc-zeroMay 2022View details →

dryad36/100