OCBIL theory: towards an integrated understanding of the evolution, ecology and conservation of biodiversity on old, climatically buffered, infertile landscapes

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    Abstract

    OCBIL theory aims to develop an integratedseries of hypotheses explaining the evolution andecology of, and best conservation practices for, biotaon very old, climatically buffered, infertile landscapes(OCBILs). Conventional theory for ecology and evolutionaryand conservation biology has developed primarilyfrom data on species and communities fromyoung, often disturbed, fertile landscapes (YODFELs),mainly in the Northern Hemisphere. OCBILs are rare,but are prominent in the Southwest Australian FloristicRegion, South Africa’s Greater Cape, and Venezuela’sPantepui Highlands. They may have been more commonglobally before Pleistocene glaciations. Based onthe premise that natural selection has favoured limiteddispersability of sedentary organisms, OCBILs shouldhave elevated persistence of lineages (GondwananHeritage Hypothesis) and long-lived individuals(Ultimate Self Hypothesis), high numbers of localisedrare endemics and strongly differentiated populationsystems. To counter such natural fragmentation andinbreeding due to small population size, ecological,cytogenetic and genetic mechanisms selecting for theretention of heterozygosity should feature (the JamesEffect). The climatic stability of OCBILs should beparalleled by persistence of adjacent semi-arid areas,conducive to speciation (Semiarid Cradle Hypothesis).Special nutritional and other biological traits associatedwith coping with infertile lands should be evident,accentuated in plants, for example, through waterforagingstrategies, symbioses, carnivory, pollinationand parasitism. The uniquely flat landscapes of southwesternAustralia have had prolonged presence of salinelakes along palaeoriver systems favouring evolution ofaccentuated tolerance to salinity. Lastly, unusual resiliencesand vulnerabilities might be evident amongOCBIL organisms, such as enhanced abilities to persistin small fragmented populations but great susceptibilityto major soil disturbances. In those places where it ismost pertinent, OCBIL theory hopefully lays a foundationfor future research and for better informedconservation management.
    Original languageEnglish
    Pages (from-to)49-86
    JournalPlant and Soil
    Volume322
    Issue number1/2
    Publication statusPublished - 2009

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