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opencc-zeroAug 2022View details →

The functional role and diversity of soil nematodes are stronger at high elevation in the lesser Himalayan mountain ranges

Soil nematodes are a foremost component of terrestrial biodiversity, they display the whole gamut of trophic guilds and life strategies, and by their activity, affect major ecosystem process, such as organic matter degradation and carbon cycling. Based on nematodes' functional types, nematode community indices have been developed, and can be used to link variation in nematodes community composition and ecosystem processes. Yet, the use of these indices has been mainly restricted to anthropogenic stresses. In this study, we propose to expand the use of nematodes' derived ecological indices in order to link soil and climate properties with soil food webs, and ecosystem processes that all vary along steep elevation gradients. For this purpose, we explored how elevation affects the trophic and functional diversity of nematode communities sampled every 300 m, from about 1000 m to 3700 m above sea level, across four transects in the lesser Himalayan range of Jammu and Kashmir. We found that (1) the trophic and functional diversity of nematodes increases with elevation; (2) differences in nematodes communities generate habitat-specific functional diversity; (3) the maturity index (MI), increases with elevation, while the enrichment index decreases, indicating less mature and less productive ecosystems, enhanced fungal-based energy flow, and a predominant role of nematodes in generating carbon influxes at high elevation sites. We thus confirm that the functional contribution of soil nematodes to belowground ecosystem processes, including carbon and energy flow, is stronger at high elevation. Overall, this study highlights the central importance of nematodes in sustaining soil ecosystems and brings insights into their functional role, particularly in alpine and arctic soils.

opencc-zeroNov 2021View details →

Vertical niche and elevation range size in tropical ants: implications for climate resilience

Aim: We propose that forest trees create a vertical dimension for ecological niche variation that generates different regimes of climatic exposure, which in turn drives species elevation distributions. We test this hypothesis by statistically modelling the vertical and elevation distributions and microclimate exposure of rainforest ants. Location: Wet Tropics Bioregion, Australia Methods: We conducted 60 ground-to-canopy surveys to determine the vertical (tree) and elevation distributions, and microclimate exposure of ants (101 species) at 15 sites along four mountain ranges. We statistically modelled elevation range size as a function of ant species' vertical niche breadth and exposure to temperature variance for 55 species found at two or more trees. Results: We found a positive association between vertical niche and elevation range of ant species: for every 3 m increase in vertical niche breadth our models predict a ~150% increase in mean elevation range size. Temperature variance increased with vertical height along the arboreal gradient and ant species exposure to temperature variance explained some of the variation in elevation range size. Main Conclusions: We demonstrate that arboreal ants have broader elevation ranges than ground-dwelling ants and are likely to have increased resilience to climatic variance. The capacity of species to expand their niche by climbing trees could influence their ability to persist over broader elevation ranges. We propose that wherever vertical layering exists - from oceans to forest ecosystems - vertical niche breadth is a potential mechanism driving macrogeographic distribution patterns and resilience to climate change.

opencc-zeroSep 2021View details →

Seasonal variation in community composition and distributional ranges of birds along a subtropical elevation gradient in China

Aim Seasonal variation in community composition and species distributional ranges along elevational gradients remain poorly known but are essential to inform conservation. In this study, we aim to understand how species richness, community composition, and elevational ranges of montane birds change between the breeding and the non-breeding season. Location The east slope of the southern Gaoligong Mountains, Yunnan, southwestern China, elevational range: 700 - 3400 m a.s.l.; latitudinal range: 24°56´- 26°09´ N. Methods We compared bird species richness and community composition in nine 300-m elevational bands in the breeding (April - May) and non-breeding (December - January) seasons. We also calculated seasonal elevational shifts of 97 species with sufficient data recorded in both seasons and assessed how species' traits influenced these shifts. Results Species richness declined in high and low elevations between the breeding and non-breeding season. The temporal beta diversity shift from the breeding to the non-breeding season was mainly caused by species losses rather than species gains in high- and low- elevation communities. Communities in middle elevations showed a contrasting pattern, with seasonal composition change resulting mainly from species gains. We also found that species' seasonal distribution shifts were mainly associated with breeding elevation and diet. Notably, high- and middle-elevation breeders and insectivores significantly shifted their elevational ranges downslope in the non-breeding season. In addition, species that participate in mixed-species flocks and that rely on forests also showed significant downslope shifts in the non-breeding season. Main Conclusions These results show complex patterns of the interconnectedness of bird communities along the elevational gradient. Keeping forests at middle elevations intact appears especially important as they are used in winter by species that breed at both high and middle elevations. Furthermore, our results suggested conservation actions maintaining connectedness in low and middle elevations are urgently needed to conserve regional biodiversity and highlight the importance of seasonality in montane ecosystem research.

opencc-zeroJan 2023View details →

Staying in situ or shifting range under ongoing climate change: A case of an endemic herb in the Himalaya-Hengduan Mountains across elevational gradients

Aim: How species respond to ongoing climate change has been a hot research topic, especially with the controversy in shifting range (movement) or persisting in local habitat (in situ) as the primary response. Assessing the relative roles of range shifts, phenotypic plasticity and genetic adaptation helps us predict the evolutionary fate of species. We aim to explore the evolutionary strategies of plants under climate change from a keystone herb in alpine ecosystems, Mirabilis himalaica, along its elevational gradient. Location: Himalaya-Hengduan Mountains, China. Methods: We combined evidence from population genomics and ecological data in both space and time to investigate the state of "staying" or "moving". We identified migration events by assessing historical and contemporary gene flow, and changes in species distribution. Morphological variation was compared by measuring five traits using specimen data. Moreover, we explored climate-driven genetic variation and local selection regimes acting on populations in the alpine landscape along an elevational gradient. Results: Our results argue that staying in situ by morphological variation and local genetic evolution rather than range shifting plays an important role in M. himalaica response to climate change. We first found trace evidence of upward or climatic-driven shifting along an elevational gradient, although asymmetric gene flow was restricted within microenvironments of mid-elevational populations. Furthermore, morphological variation comparisons revealed clinal variation, as resource allocation showed a declining pattern in vegetative growth but increased reproductive growth with increasing elevation. Outlier tests and environment association analyses indicated adaptative loci primarily related to thermal-driven selection and continuous adaptations to high elevation in the Himalaya-Hengduan Mountains. Main conclusions: Our findings show M. himalaica may persist in local habitats rather than shifting range under climate change, exhibiting a low risk of genomic vulnerability in current habitats. This study has important implications for improving our understanding of the evolutionary response in alpine plants to climate change.

opencc-by-4.0Feb 2023View details →

Data and code for: Red-listed plants are contracting their elevational range faster than common plants in the European Alps

Dataset of the publication Geppert C., Bertolli A., Prosser F., Marini L., (2023): Red-listed plants are contracting their elevational range faster than common plants in the European Alps. PNAS. Contacts: costanza.geppert@unipd.it - lorenzo.marini@unipd.it. This data repository consists of plant records collected in the Trento Province from 1990 to 2019, species' elevational range shifts, ecological traits, hotspots' files and R script.  Description of the dataset: please see ReadMe.docx containing information on each file and instructions for use.

Fig. 2 in Explaining mammalian abundance and elevational range size with body mass and niche characteristics

Fig. 2.—Relationship between ABD (mean abundance) and ER (elevational range size) of small mammals along the (a) Wolong, (b) Luoji, (c) Gongga, (d) Baima Snow, and (e) Sejila gradients. ABD and ER were log10(x + 1) transformed. Open circles indicate individual species (n value represents the number of species), and the best fitted line as calculated by linear regression analysis (not accounting for the effects of phylogeny) is shown.

Fig. 4 in Explaining mammalian abundance and elevational range size with body mass and niche characteristics

Fig. 4.—Scatterplots illustrating the relationships between NP (niche position) and ABD (mean abundance, a–e) and ER (elevational range size, f–j) of small mammals along the Wolong, Luoji, Gongga, Baima Snow, and Sejila gradients. All the three variables were log10(x + 1) transformed. Open circles indicate individual species, and the best fitted line as calculated by linear regression analysis (not accounting for the effects of phylogeny) is shown.

Fig. 1 in Explaining mammalian abundance and elevational range size with body mass and niche characteristics

Fig. 1.—Alternative path models used in phylogenetic path analysis to assess the relationships among body mass (MASS), niche breadth (NB), niche position (NP) on mean abundance (ABD) and elevation range size (ER) of species. The hypothesized relationships among variables are described via regression formulas shown at the top of each model and depicted by the direction of the arrows.

Fig. 3 in Explaining mammalian abundance and elevational range size with body mass and niche characteristics

Fig. 3.—Scatterplots illustrating the relationships between MASS (body mass) and ABD (mean abundance, a–e) and ER (elevational range size, f–j) of small mammals along the Wolong, Luoji, Gongga, Baima Snow, and Sejila gradients. All the three variables were log10(x + 1) transformed. Open circles indicate individual species, and the best fitted line as calculated by linear regression analysis (not accounting for the effects of phylogeny) is shown.

Fig. 5 in Explaining mammalian abundance and elevational range size with body mass and niche characteristics

Fig. 5.—Scatterplots illustrating the relationships between NB (niche breadth) and ABD (mean abundance, a–e) and ER (elevational range size, f–j) of small mammals along the Wolong, Luoji, Gongga, Baima Snow, and Sejila gradients. All the three variables were log10(x + 1) transformed. Open circles indicate individual species, and the best fitted line as calculated by linear regression analysis (not accounting for the effects of phylogeny) is shown.

Fig. 6 in Explaining mammalian abundance and elevational range size with body mass and niche characteristics

Fig. 6.—Best supported model from phylogenetic path analysis along the five gradients. Arrows represent the effects of MASS (body mass), NP (niche position), and NB (niche breadth) on ABD (mean abundance) and ER (elevational range size), and values aside are standardized regression coefficients. Red arrows indicate positive effects and blue arrows indicate negative effects. See the results of all six candidate models for each gradient in Supplementary Data SD7.

opencc-zeroAug 2023View details →

Osmanthus plastid genome sequence for: Plastid genomes reveal evolutionary shifts in elevational range and flowering time of Osmanthus (Oleaceae)

Species of Osmanthus are economically important ornamental trees, yet information regarding their plastid genomes (plastomes) has rarely been reported, thus hindering taxonomic and evolutionary studies of this small but enigmatic genus. Here, we performed comparative genomics and evolutionary analyses on plastomes of 16 of the 28 currently accepted species, with 11 plastomes newly sequenced. Phylogenetic studies identified four main lineages within the genus that are here designated: 'Caucasian Osmanthus' (corresponding to O. decorus), 'Siphosmanthus' (corresponding to O. sect. Siphosmanthus), 'O. serrulatus + O. yunnanensis', and 'Core Osmanthus' (corresponding to O. sect. Osmanthus + O. sect. Linocieroides). Molecular clock analysis suggested that Osmanthus split from its sister clade c. 15.83 Ma. The estimated crown ages of the lineages were the following: genus Osmanthus at 12.66 Ma; 'Siphosmanthus' clade at 5.85 Ma; 'O. serrulatus + O. yunnanensis' at 4.89 Ma; 'Core Osmanthus' clade at 6.2 Ma. Ancestral state reconstructions and trait mapping showed that ancestors of Osmanthus were spring-flowering and originated at lower elevations. Phylogenetic principal component analysis clearly distinguished spring-flowering species from autumn-flowering species, suggesting that flowering time differentiation is related to the difference in ecological niches. Nucleotide substitution rates of 80 common genes showed a slow evolutionary pace and low nucleotide variations, all genes being subjected to purifying selection.