Biology subjects

Larcombe, M. J.

Publications and source records attributed to Larcombe, M. J..

3 recordsLinked to original sources

bioRxiv2023

Winners and losers under past and future climate change

Understanding the historical and physiological context of species vulnerabilities to climate change is a crucial step in predicting "winners" and "losers" under climate change. However, few studies have compared the magnitude and mechanisms of extant species responses to climate change in both the past and the future. By combining temporally contrasting range and niche projections, we show that range shifts in the next 50 years will need to be more extreme than in the past 6000 years to track climate niches in a large plant radiation. A new subset of physiological niche traits, particularly temperature and radiation tolerance, will be strong filters of range occupancy under anthropogenic compared with Holocene climate change. In the absence of migration, temperature niche shifts tracking the magnitude of climate change will also be required for many species to maintain their present ranges. Where range shifts occur, our results suggest that communities will be restructured differently in different habitats, with widespread range contraction in the mountains and potential latitudinal range expansion in the lowlands. Our study adds to a growing body of evidence that despite the threats posed by climate change to many species, not all species will experience unmitigated loss, and that it may be possible to predict which species are most at risk based on physiological and geographical traits.

ecology↗

bioRxiv2022

Different factors drive community assembly of rare and common ectomycorrhizal fungi

1.Understanding what drives community assembly processes and how communities respond to environmental gradients are fundamental goals in community ecology. Ectomycorrhizal fungi support major forest systems across the globe, but the diversity, distribution and environmental controls affecting ectomycorrhizal community composition are unknown in many regions, particularly in the southern hemisphere. Here we investigate the assembly of ectomycorrhizal fungal communities based on eDNA samples from 81 Nothofagus forests across New Zealands South Island. We apply zeta diversity analysis and multi-site generalised dissimilarity modelling (MS-GDM) to investigate assembly patterns and quantify the effects of 43 biotic and environmental variables on community turnover. The zeta diversity MS-GDM framework differentiates between the environmental factors driving turnover of rare and common species, so provides a more complete picture of community dynamics than traditional beta diversity analyses. Results showed that community assembly was dominated by deterministic rather than stochastic processes. Soil variables were important drivers across the full range of rare, intermediate and common species. Ground cover variables, forest patch size and rainfall had greater effects on turnover of rare species, whereas temperature variables and host tree size had greater effects on common species turnover. Applying these methods for the first time to fungi demonstrates that there are distinct differences in the ecological processes affecting different aspects of the ectomycorrhizal community, which has important implications for understanding the functional effects of community responses to environmental change.

ecology↗

bioRxiv2018

The dimensions of species diversity

Diversification processes underpin the patterns of species diversity that fascinate biologists. Two competing hypotheses disagree about the effect of competition on these processes. The bounded hypothesis suggests that species diversity is limited (bounded) by competition between species for finite niche space, while the unbounded hypothesis proposes that evolution and ecological opportunity associated with speciation, render competition unimportant. We use phylogenetically structured niche modelling, to show that processes consistent with both these diversification models have driven species accumulation in conifers. In agreement with the bounded hypothesis, niche competition constrained diversification, and in line with the unbounded hypothesis, niche evolution and partitioning promoted diversification. We then analyse niche traits to show that these diversification enhancing and inhibiting processes can occur simultaneously on different niche dimensions. Together these results suggests a new hypothesis for lineage diversification based on the multi-dimensional nature of ecological niches that accommodates both bounded and unbounded diversification processes.

evolutionary biology↗