Ocbil Theory as a Potential Unifying Framework for Investigating Narrow Endemism in Mediterranean Climate Regions

OCBIL theory addresses the ecology, evolution, and conservation of biodiversity and cultural diversity on old climatically buffered infertile landscapes, which are especially prominent in southwest Australia and the Greater Cape Region of South Africa. Here, as a contribution to general theory on endemism, a few case studies are briefly discussed to ascertain the relevance of hypotheses in OCBIL theory to understanding narrow endemism in Mediterranean climate regions. Two new conservation management hypotheses are also introduced-minimising disturbance of OCBILS and conserving cross-culturally to achieve best outcomes. Case studies of endemics in southwest Australia (e.g., Eucalyptus caesia, Anigozanthos, Cephalotaceae, Daspypogonaceae) and South Africa (Moraea, Conophytum) and more limited evidence for the Mediterranean Region conform to OCBIL theory predictions. Narrow endemics, concentrated in OCBILs, have diverse origins that embrace major hypotheses of OCBIL theory such as prolonged persistence and diversification in refugia, limited dispersal, coping with inbreeding in small disjunct population systems (the James Effect), special adaptations to nutrient-deficient soils, and special vulnerabilities (e.g., to soil disturbance and removal). Minimising disturbance to OCBILs is recommended as the primary conservation strategy. OCBIL theory has a potentially significant role to play in advancing understanding of narrow endemism of plants in Mediterranean climate regions and elsewhere.

OCBIL theory: a new science for old ecosystems

This paper is an introduction to the special issue of the Biological Journal of the Linnean Society entitled OCBIL theory: a new science for old ecosystems. Firstly, we elaborate on the origins and development of OCBIL theory, which argues that landscape age, climatic buffering and soil fertility are key environmental dimensions shaping ecological and evolutionary processes across different scales. We then consider the 21 contributions made in this special issue in terms of cutting edge advances in the Southern Hemisphere that test, explore and apply aspects of OCBIL theory at the end of its first decade of formal publication. More attempts at refutation are urged, as untested aspects remain controversial. Lastly, a concluding discussion is offered on promising new lines of enquiry to develop the theory further and ensure its global application to pressing conservation issues facing biological and cultural diversity. Although OCBILs are absent or rare in much of the postglacial and periglacial Northern Hemisphere, we demonstrate, in south-west Europe and North America, starting with California, that they are likely to be found, thus extending the implications and applications of OCBIL theory in new directions. We also propose that, in many ways, Noongar Aboriginal cosmology from south-west Australia has developed sophisticated insights about ancient uplands that are precursors to key ideas in OCBIL theory.

Interactions between the introduced European honey bee and native bees in urban areas varies by year, habitat type and native bee guild

European honey bees have been introduced across the globe and may compete with native bees for floral resources. Compounding effects of urbanization and introduced species on native bees are, however, unclear. Here, we investigated how honey bee abundance and foraging patterns related to those of native bee abundance and diversity in residential gardens and native vegetation remnants for 2 years in urbanized areas of the Southwest Australian biodiversity hotspot and assessed how niche overlap influenced these relationships. Honey bees did not overtly suppress native bee abundance; however, complex relationships emerged when analysing these relationships according to body size, time of day and floral resource levels. Native bee richness was positively correlated with overall honeybee abundance in the first year, but negatively correlated in the second year, and varied with body size. Native bees that had higher resource overlap with honey bees were negatively associated with honey bee abundance, and resource overlap between honey bees and native bees was higher in residential gardens. Relationships with honey bees varied between native bee taxa, reflecting adaptations to different flora, plus specialization. Thus, competition with introduced bees varies by species and location, mediated by dietary breadth and overlap and by other life-history traits of individual bee species.