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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.

We examined the floristics of granitoid inselbergs in the hitherto poorly documented south-eastern region of the Southwest Australian Floristic Region (SWAFR) and adjacent Great Western Woodlands, addressing several hypotheses of OCBIL (old, climatically buffered, infertile landscapes) theory. We found exceptional taxon richness (1550 taxa on 89 inselbergs, with 58 well-sampled inselbergs and 1493 taxa chosen for detailed analyses). Granite inselberg endemism declined towards the arid inland, although taxon richness did not. OCBILs are likely to be found up to 500 km inland, not ~300 km as previously hypothesized. Hybrids were extremely rare on the 58 inselbergs analysed, whereas rare species, including singletons, were abundant. Conversely, exotic weeds were less common than in the whole SWAFR flora (8.2% vs 12.8%). Granite plant communities were distributed in bands parallel to the south coast, approximating the general transition from the Esperance and Boylya Floristic Districts across the SWAFR boundary north into the Arid Zone’s Great Western Woodlands. Positive correlations were found between several plant life forms and inselberg area. There was a decrease from the coast inland for most life forms, except for annual and graminoid herbs that increased in taxa inland. Thus, inselberg floristics exemplify the coast-to-inland OCBIL transition in this global biodiversity hotspot.

OCBIL theory was introduced as a contribution towards understanding the evolution, ecology and conservation of the biological and cultural diversity of old, climatically buffered, infertile landscapes (OCBILs), especially in the Southern Hemisphere. The theory addresses some of the most intransigent environmental and cultural trends of our time – the ongoing decline of biodiversity and cultural diversity of First Nations. Here we reflect on OCBILs, the origins of the theory, and its principal hypotheses in biological, anthropological and conservation applications. The discovery that threatened plant species are concentrated in the Southwest Australian Floristic Region (SWAFR) on infertile, phosphorous-impoverished uplands within 500 km of the coast formed the foundational framework for OCBIL theory and led to the development of testable hypotheses that a growing literature is addressing. Currently, OCBILs are recognized in 15 Global Biodiversity Hotspots and eight other regions. The SWAFR, Greater Cape Floristic Region of South Africa and South America’s campos rupestres (montane grasslands) are those regions that have most comprehensively been investigated in the context of OCBIL theory. We summarize 12 evolutionary, ecological and cultural hypotheses and ten conservation-management hypotheses being investigated as recent contributions to the OCBIL literature.

OCBIL theory is a multi-hypothesis formulation aimed towards an understanding of the evolution, ecology and conservation of biological and cultural diversity on old, climatically buffered, infertile landscapes (OCBILs). OCBILs have been in existence contemporaneously with rainforest since Gondwanan times. Such landscapes are common in areas of eucalypt species richness embraced by Australia’s two Global Biodiversity Hotspots, the Southwest Australian Floristic Region and the Forests of East Australia. Here, I summarize evidence pertaining to the eucalypts in the context of a recent reformulation of OCBIL theory into 12 evolutionary, ecological and cultural hypotheses and ten conservation management hypotheses. A compelling argument emerges for a new interpretation of the eucalypts evolving out of the OCBILs, rather than out of the rainforests as traditionally interpreted. This calls for a significant reinterpretation of best conservation management of the eucalypts. For example, traditional ideas on application of fire in eucalypt communities regarded as well adapted to this disturbance need to give way to a more nuanced and cautious view. This review of eucalypts seen as evolving out of the OCBILs helps in understanding the group from several new perspectives. Interpretation of other sedentary plant and animal groups as out of the OCBILs is commended for further study.

The flora of the Southwest Australian Floristic Region (SWAFR) is characterized by remarkable richness, endemism, spatial turnover and numbers of threatened taxa. Increasingly, evolutionary history is recognized as contributing to SWAFR biogeographical patterns, culminating in the theory of old, climatically buffered, infertile landscapes (OCBILs) [and their counterpoint: young, often disturbed, fertile landscapes (YODFELs)]. For the SWAFR, we: (1) developed a spatially explicit distribution of OCBILs and YODFELs; (2) analysed the spatial distribution of Threatened and Priority (Data Deficient) flora; and (3) tested the hypotheses that Threatened and Priority flora will be most strongly represented in OCBILs and will have small geographical ranges. We found that OCBILs and YODFELs dominated spatially distinct portions of the SWAFR. Threatened and Priority flora were not uniformly or randomly distributed and were more strongly characterized by narrow-range endemics than the non-Threatened flora. The occurrence of Threatened and Priority flora was positively correlated with the age of surface exposure of landscape features and unique geological features of limited extent (if not YODFELs). The concentration of Threatened flora in OCBILs provides the opportunity to improve conservation management through investigations of how plant traits favoured by evolution in OCBILs might increase or decrease the susceptibility of the flora to anthropogenic threats.

Geophytes are a considerable component of Southwest Australian flora and thus, unsurprisingly, feature heavily in the diets and culture of Noongar First Nations people of this old, climatically buffered, infertile landscape-dominated global biodiversity hotspot. Of ~650 geophyte species recorded in south-western Australia, 90 are known traditional Noongar foods. Despite the significant role of geophytes in Noongar traditional lives, there is little published knowledge of the ecological effects of harvesting geophytes. We measured and observed soil and plant outcomes of tuber harvest for two Noongar staple species of Platysace Bunge to test whether it improved soil conditions for plant growth and/or aided tuber availability, as suggested for other Australian Aboriginal root crops. Harvesting of Platysace deflexa led to increases in some soil nutrient levels and, unexpectedly, to an increase in bulk density. Platysace deflexa stem abundance was restored to the pre-harvest level within 1 year post-harvest, whereas tuber weight and volume were less than pre-harvest levels after 2 years. A post-harvest increase in the proportion of small tubers in crops suggests that harvest has a renewing and homogenizing effect on tubers. Site-based differences in post-harvest P. deflexa and Platysace trachymenioides quantity of tubers were consistent with preferential harvest of some populations by present-day Noongar families and their ancestors.

OCBIL theory provides a basis for understanding of the evolution and ecology of biota on old, climatically buffered, infertile landscapes (OCBILs) worldwide. Here, we test a genetic hypothesis presented in OCBIL theory that predicts highly differentiated intraspecific population systems on OCBILs vs. more limited differentiation on young, often disturbed, fertile landscapes (YODFELs). We examined patterns of genomic and morphological divergence in Banksia seminuda across OCBILs and YODFELs in south-western Australia. We also used these data to determine whether these OCBIL and YODFEL populations represent distinct subspecific lineages, a point of previous contention among taxonomists. As hypothesized, genomic analyses based on 3466 SNP loci revealed strong structuring within B. seminuda, with high differentiation across narrow geographic scales among OCBIL populations vs. lower differentiation across much larger geographic scales among YODFEL populations. In addition, genomic and morphological divergence was found between OCBIL and YODFEL populations, providing comprehensive quantitative evidence for two subspecies. These findings have taxonomic implications for the species and provide support for OCBIL theory and its insights into the evolution, ecology and conservation of biota on ancient landscapes.

Occurring across all southern hemisphere continents except Antarctica, old, climatically buffered, infertile landscapes (OCBILs) are centres of biological richness, often in biodiversity hotspots. Among a matrix of young, often disturbed, fertile landscapes (YODFELs), OCBILs are centres of endemism and diversity in the exceptionally rich flora of the south-west Australian global biodiversity hotspot, home to Noongar peoples for ≥ 48 000 years. We analysed contemporary traditional Noongar knowledge of adjacent OCBILs (e.g. granite outcrops) and YODFELs (e.g. creekline fringes) both at a single site and in two larger areas to test whether patterns of disturbance dictated by Noongar custom align with OCBIL theory. We found that Noongar traditional knowledge reflects a regime of concentrated YODFEL rather than OCBIL disturbance—a pattern which aligns with maximal biodiversity preservation. SIMPER testing found traditional Noongar OCBIL and YODFEL activities are 64–75% dissimilar, whereas Pearson’s chi-square tests revealed camping, burning, travelling through country and hunting as primarily YODFEL rather than OCBIL activities. We found that Noongar activities usually avoid OCBIL disturbance. This combined with high floristic diversity following enduring First Peoples’ presence, suggests that traditional Noongar knowledge is valuable and necessary for south-west Australian biodiversity conservation. Similar cultural investigations in other OCBIL-dominated global biodiversity hotspots may prove profitable.

High gene flow and a population structure corresponding to human rather than geographical drivers are likely to be genetic patterns of human-dispersed plant taxa. We examined variation in geographical structure and gene flow estimates based on three non-coding regions of plastid DNA in three south-west Australian members of the Platysace genus to identify whether a human influence on dispersion of utilized taxa was detectable. Edible tubers of Platysace deflexa and Platysace trachymenioides have been harvested historically by Noongar traditional owners, whereas Platysace effusa has no known cultural significance. We found differences between utilized and non-utilized taxa, particularly when considered against the generally complex phylogeographical patterning in south-west Australian plant taxa. Platysace effusa showed a pattern of high population divergence, low gene flow and multiple refugia, consistent with a long evolutionary history, past climatic oscillations and persistence in a highly fragmented landscape. In contrast, higher gene flow estimates, less divergence between populations and common haplotypes in P. deflexa and in P. trachymenioides over the south-eastern part of its range are consistent with anthropogenic influences. This study contributes to the understanding of human influences on south-west Australian plant taxa that have been present since the late Pleistocene, but to date have received little scientific attention.

Background and Aims In plants, the spatial and genetic distance between mates can influence reproductive success and offspring fitness. Negative fitness consequences associated with the extremes of inbreeding and outbreeding suggest that there will be an intermediate optimal outcrossing distance (OOD), the scale and drivers of which remain poorly understood. In the bird-pollinated Anigozanthos manglesii (Haemodoraceae) we tested (1) for the presence of within-population OOD, (2) over what scale it occurs, and (3) for OOD under biologically realistic scenarios of multi-donor deposition associated with pollination by nectar-feeding birds. Methods We measured the impact of mate distance (spatial and genetic) on seed set, fruit size, seed mass, seed viability and germination success following hand pollination from (1) single donors across 0 m (self), Key results Inter-mate distance had a significant impact on single-donor reproductive success, with selfed and nearest-neighbour ( Conclusions Collectively, single- and multi-donor pollinations indicated evidence for a near-neighbour OOD within A. manglesii. A survey of the literature suggests that within-population OOD may be more characteristic of plants pollinated by birds than those pollinated by insects.

†Background The issue of determining the most appropriate rank for each accepted taxon fuels ongoing controversy throughout systematics. The particularly marked escalation of such issues in modern Australian orchid systematics merits examination, not only because of wider implications in taxonomy but also because of direct effects on studies of comparative biology and conservation management. †Scope This paper briefly reviews the causes of recent taxonomic turmoil for Australian orchids and outlines new research opportunities and conservation implications arising from an improved understanding of their molecular phylogenetics. †Conclusions DNA sequencing and intensified field work have contributed towards a much improved understanding of Australian orchid systematics. Great progress has been made in discerning monophyletic groups or clades. Fresh interpretations of morphological evolution have been made possible by comparisons with the results of DNA analyses. Significant conceptual shifts from polymorphic species concepts to biological and phylogenetic concepts have also elevated the discovery and description of new species. Consequently, over the past decade, the number of Australian orchid species recognized by taxonomists has risen from approx. 900 to 1200. Similarly, the number of genera recognized by some taxonomists has increased from 110 to 192, resulting in 45% of Australian species/subspecies being assigned a new generic epithet since 2000. At higher taxonomic levels, much of the recent controversy in Australian orchid systematics reflects a divergence in views about where to split and assign formal names within unequivocally monophyletic groups. Differences regarding typification in the case of Caladenia have added additional confusion and complexity. However, new insights into and research opportunities concerning speciation processes in orchids have arisen from the wealth of new data and discrimination of species. Robustly supported molecular analyses of most clades enable comparative biological studies of Australian orchids to be conducted as never before. Outstanding subjects exist for exploring pollination by sexual deception and understanding the intricacies of mycorrhizal relationships and orchid conservation biology.

Granite outcrops represent an isolated island habitat and, in ancient landscapes, may harbour species with complex evolutionary histories. Phylogenetic analysis of these species may reveal the influences of evolutionary processes over long time frames. Phylogenetic relationships from chloroplast and nuclear genome analysis were investigated in Eucalyptus caesia, a bird-pollinated mallee endemic to granite outcrops in the South-western Australian Floristic Region. The results obtained revealed high population and haplotype divergence, suggesting restriction to the specific habitat of granite outcrops over long time frames with genetic drift as the most significant evolutionary force. The hypothesis of derivation of ssp. magna from ssp. caesia was not supported by the pattern of diversity in either the chloroplast or the nuclear genome and the two subspecies were not monophyletic. Eucalyptus caesia displays significant clonality yet little evidence of inbreeding depression, suggesting deleterious mutations causing inbreeding depression have been purged. © 2008 Department of Environment and Conservation. Journal compilation © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 93, 177–188.

A phylogenetic analysis of plastid DNA sequences from the trn L-F region corroborates the hypothesis that Haemodoraceae, a small monocotyledonous family centred in southwestern Australia, are monophyletic with relationships to Philydraceae, Pontederiaceae and Commelinaceae. It also supports the long-standing recognition of two subfamilies. In Conostylidoideae Tribonanthes falls in an isolated position, thus supporting its segregation as a recently recognized monogeneric tribe. Tribal status for Phlebocarya is not supported as this taxon is unexpectedly placed in Conostylideae as sister to Conostylis–Blancoa. Macropidia falls as sister to Anigozanthos . The DNA tree permits continued recognition of Macropidia and Blancoa as distinct genera, contrary to a recent morphological cladistic analysis. Haemodoroideae fall into two clades: ( Dilatris(Lachnanthes+Haemodorum )) and ( Xiphidium(Schiekia+Wachendorfia )). It is unlikely that Haemodoraceae are of Gondwanan origin, and the phylogenetic pattern indicates a largely relictual distribution with a recent radiation in Western Australia.