Rapid plant diversification: Planning for an evolutionary future

Abstract

Systematic conservation planning is a branch of conservation biology that seeks to identify spatially explicit options for the preservation of biodiversity. Alternative systems of conservation areas are predictions about effective ways of promoting the persistence of biodiversity; therefore, they should consider not only biodiversity pattern but also the ecological and evolutionary processes that maintain and generate species. Most research and application, however, has focused on pattern representation only. This paper outlines the development of a conservation system designed to preserve biodiversity pattern and process in the context of a rapidly changing environment. The study area is the Cape Floristic Region (CFR), a biodiversity hotspot of global significance, located in southwestern Africa. This region has experienced rapid (post-Pliocene) ecological diversification of many plant lineages; there are numerous genera with large clusters of closely related species (flocks) that have subdivided habitats at a very fine scale. The challenge is to design conservation systems that will preserve both the pattern of large numbers of species and various natural processes, including the potential for lineage turnover. We outline an approach for designing a system of conservation areas to incorporate the spatial components of the evolutionary processes that maintain and generate biodiversity in the CFR. We discuss the difficulty of assessing the requirements for pattern versus process representation in the face of ongoing threats to biodiversity, the difficulty of testing the predictions of alternative conservation systems, and the widespread need in conservation planning to incorporate and set targets for the spatial components (or surrogates) of processes.T here are numerous pleas in the literature for integrated systems of conservation areas that will maintain disturbance regimes, migratory corridors, habitat diversity, landscape connectivity, evolutionary templates, and other spatial features necessary for the maintenance of evolutionary processes (1-4). There has been some debate as to whether priority should be given to areas supporting ancestral taxa with evolutionary potential (5, 6) or those representing evolutionary fronts of currently speciating taxa (7-10). Recently, Moritz and coworkers (11) have used comparative phylogeography to identify areas that encompass both the adaptive and historical components of genetic diversity of vertebrates in the rainforests of northeastern Australia. However, there have been no studies that attempt to identify the spatial components of a wide spectrum of evolutionary processes or to set explicit targets for their protection in particular regions.If we are to plan for an evolutionary future, then evolutionary processes-those that maintain genetic diversity and promote diversification-must be explicitly considered, and represented, in the conservation plan (1,11,12). This is not a trivial issue. There are very few places in the world, in particular in its endemic-rich and ...

Global patterns and determinants of vascular plant diversity

“…We find that translated into species numbers, the Cape flora has more than twice as many species (on average 655 species per Ϸ12,100 km 2 grid cell more; maximum: 1,637) per unit area than expected given its contemporary environment and topography, confirming, from a global perspective, its outstanding richness (44). The potential causes of the unique plant diversity of the Cape region are still debated and include climatic shifts from summer to winter rains starting in the Oligocene, pollinator specialization, mesoscale habitat specialization, and fire regimes, giving rise to an enormous diversification in some clades (45,45). Crucially, we find that many regional differences in species richness that have classically been attributed to historical factors can also be predicted by contemporary differences in the environment.…”

Monophyly and relationships of the tribe Exaceae (Gentianaceae) inferred from nuclear ribosomal and chloroplast DNA sequences

“…The phylogeny of this genus is still unknown, so the place of origin of Sebaea can not be suggested yet. Examples showed that the species richness in the Cape flora probably resulted from rapid and recent (7-8 MY) diversification (Cowling and Pressey, 2001;Richardson et al, 2001b). This might also be the case for Sebaea.…”

The current biodiversity extinction event: Scenarios for mitigation and recovery

“…This is critical to identifying corridors or ''landscape linkages'' that facilitate the continuity among the less damaged habitats and help secure biological processes critical to functioning ecosystems (37). The approach is well exemplified in protocols established by Cowling et al (38) for maintenance of viable ecological and evolutionary processes in the Cape Floristic Region, a remarkable area containing 12,000 plant species, 80% of which are endemic.…”