Browsing by Author "Caruso, Tancredi"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Biotic interactions are an unexpected yet critical control on the complexity of an abiotically driven polar ecosystem
    Lee, Charles K.; Laughlin, Daniel C.; Bottos, Eric M.; Caruso, Tancredi; Joy, Kurt; Barrett, John E.; Brabyn, Lars; Nielsen, Uffe N.; Adams, Byron J.; Wall, Diana H.; Hopkins, David W.; Pointing, Stephen B.; McDonald, Ian R.; Cowan, Don A.; Banks, Jonathan C.; Stichbury, Glen A.; Jones, Irfon; Zawar-Reza, Peyman; Katurji, Marwan; Hogg, Ian D.; Sparrow, Ashley D.; Storey, Bryan C.; Green, T.G. Allan; Cary, S. Craig (Springer Nature, 2019-02-15)
    Abiotic and biotic factors control ecosystem biodiversity, but their relative contributions remain unclear. The ultraoligotrophic ecosystem of the Antarctic Dry Valleys, a simple yet highly heterogeneous ecosystem, is a natural laboratory well-suited for resolving the abiotic and biotic controls of community structure. We undertook a multidisciplinary investigation to capture ecologically relevant biotic and abiotic attributes of more than 500 sites in the Dry Valleys, encompassing observed landscape heterogeneities across more than 200 km2. Using richness of autotrophic and heterotrophic taxa as a proxy for functional complexity, we linked measured variables in a parsimonious yet comprehensive structural equation model that explained significant variations in biological complexity and identified landscape-scale and fine-scale abiotic factors as the primary drivers of diversity. However, the inclusion of linkages among functional groups was essential for constructing the best-fitting model. Our findings support the notion that biotic interactions make crucial contributions even in an extremely simple ecosystem.
  • Thumbnail Image
    Nematodes in a polar desert reveal the relative role of biotic interactions in the coexistence of soil animals
    Caruso, Tancredi; Hogg, Ian D.; Nielsen, Uffe N.; Bottos, Eric M.; Lee, Charles K.; Hopkins, David W.; Cary, S. Craig; Barrett, John E.; Green, T.G. Allan; Storey, Bryan C.; Wall, Diana H.; Adams, Byron J. (Springer Nature, 2019-02-15)
    Abiotic factors are major determinants of soil animal distributions and their dominant role is pronounced in extreme ecosystems, with biotic interactions seemingly playing a minor role. We modelled co-occurrence and distribution of the three nematode species that dominate the soil food web of the McMurdo Dry Valleys (Antarctica). Abiotic factors, other biotic groups, and autocorrelation all contributed to structuring nematode species distributions. However, after removing their effects, we found that the presence of the most abundant nematode species greatly, and negatively, affected the probability of detecting one of the other two species. We observed similar patterns in relative abundances for two out of three pairs of species. Harsh abiotic conditions alone are insufficient to explain contemporary nematode distributions whereas the role of negative biotic interactions has been largely underestimated in soil. The future challenge is to understand how the effects of global change on biotic interactions will alter species coexistence.