Differential exposure and susceptibility to threats based on evolutionary history: how OCBIL theory informs flora conservation

Abstract

Abstract Optimal conservation approaches have been proposed to differ for biota with contrasting evolutionary histories. Natural selection filters the distribution of plant traits over evolutionary time, with the current expression of traits mediating susceptibility to contemporary and often novel threats. We use old, climatically buffered, infertile landscape (OCBIL) theory to compile predictions regarding differences in exposure and susceptibility to key threats between OCBIL and young, often disturbed, fertile landscape (YODFEL) flora. Based on literature and existing data from the Southwest Australian Floristic Region (SWAFR), we evaluate evidence in support of our predictions, finding strong theoretical and empirical support for the proposition that exposure and/or impact of many threats differs between OCBILs and YODFELs. OCBILs have more exposure to land clearance from mining, whereas many YODFELs have greater exposure to land clearance from agriculture, and urban and industrial land uses, and greater overall levels of habitat loss and fragmentation. OCBIL flora are more susceptible to pathogens and extremes of fire interval than YODFEL flora, but conversely may have a greater capacity to persist in smaller populations if small populations featured in the evolutionary history of the species prior to anthropogenic fragmentation, and have substantial resistance to weed invasion. We argue that consideration of evolutionary history has an important role in informing conservation management.