The influence of abiotic processes, competition and predation on the community structure of rodents and shrews.
Year: 2012
Type: dissertation
Abstract: Predation and abiotic processes rather than competition should influence the community structure \nof rodents and shrews with life histories characterised by high fecundity, short longevity and \nunstable populations. I investigated the influence of abiotic processes, predation and competition \non three parameters of community structure (species composition, phenotypic and phylogenetic \nniches) of rodents and shrews at Mkhuze and Kube Yini, two game reserves in KwaZulu-Natal, \nSouth Africa, using null models and multivariate analyses. Rodents and shrews were sampled \nbetween 2007 and 2009. Sample-based rarefaction curves indicated that rodent species richness \nwas higher at Mkhuze than at Kube Yini, while shrew species richness was identical at both \nreserves. Species richness estimators indicated that estimates of species richness were fairly \naccurate, hence strengthening the results from my null model analyses. \nI found evidence that immigration and extinction operating at a regional scale influenced rodent \nspecies composition. Moreover, habitat filtering operating at a local scale influenced rodent and \nshrew species composition. These processes produced nested assemblages: species present at \nspecies-poor sites were subsets of species present at species-rich sites. Habitat filtering also \ninfluenced the phenotypic niche of rodents and shrews: sympatric species showed similar \nphenotypic adaptations (phenotypic niches were underdispersed), probably in response to similar \nfood requirements. Furthermore, shrew phenotypic traits showed a convergent evolution, and local \nassemblages comprised distantly related species (phylogenetic evenness), suggesting the influence \nof habitat filtering on the phylogenetic niche structure of shrews. \nPredation influenced shrew phenotypes. Bullae and ears were underdispersed and larger than \nexpected by chance, probably to reduce predation risk through increased hearing sensitivity. In \ncontrast, I found no evidence that predation influenced the rodent phenotypic niche. \nCompetition influenced the phenotypic niches of rodents and shrews in species-rich assemblages \n(phenotypic niches were overdispersed). In these assemblages, the coexistence of species was \nfacilitated by dietary and microhabitat partitioning. Competition also influenced the phylogenetic \nniche of rodents: phenotypic traits showed a convergent evolution, and local assemblages \ncomprised closely related species (phylogenetic clustering). \nIn conclusion, both abiotic and biotic processes influenced different parameters of the community \nstructure of rodents and shrews. However, despite similar life-history traits, the community \nstructure of local assemblages differed between rodents and shrews. Comparing patterns and \nprocesses of community structure across taxa would help find general trends of community \norganisation.
Author: Gwenaelle. Delcros
Language: English
Subfield: Ecology
Field: Environmental Science
Domain: Physical Sciences
SDG: Life on land
Open Access status: green
OpenAlex ID: W1604755702