Continental Biodiversity Research Articles

Quantifying Heatwaves’ Contemporary Association with Continental Biodiversity

In recent years, extreme high temperature events have created great threat to humanity and socio-economy. However, a comprehensive evaluation on the degrees to which ecosystems are affected by heatwaves is yet to be fully resolved and becomes a hot-spot in climate and ecological research. This study aims to quantify the relationship between global heatwave occurrence and environmental indicators such as continental biodiversity quantified by the Living Planet Index, thereby generating a way to understand the extent to which future heatwaves may impact the planet. Analyzing global meteorological data from the last 43 years (1980-2022), heatwave definition is standardized to daily maximum temperatures over the 90th percentile (threshold), with a consecutive occurrence of at least three days, in the 1981-2010 climatological period. A significantly strong, negative correlation (coefficient of determination=0.766) between the occurrence of the standardized heatwave and continental biodiversity is established through Pearson correlation analysis and linear regression, followed by Student-t test. This research provides the scientific community a better comprehension to the variability of heatwaves during the past decades over global continental regions. Through diagnosing the heatwave-biodiversity relationship and the underlying mechanism of how extreme temperature events impact ecosystems, this research will shed light on a better solution to alleviate the impact of heatwaves on biodiversity, or better, to alleviate global warming purposefully.

END-PERMIAN BURNOUT: THE ROLE OF PERMIAN–TRIASSIC WILDFIRES IN EXTINCTION, CARBON CYCLING, AND ENVIRONMENTAL CHANGE IN EASTERN GONDWANA

ABSTRACTWildfire has been implicated as a potential driver of deforestation and continental biodiversity loss during the end-Permian extinction event (EPE; ∼ 252 Ma). However, it cannot be established whether wildfire activity was anomalous during the EPE without valid pre- and post-EPE baselines. Here, we assess the changes in wildfire activity in the high-latitude lowlands of eastern Gondwana by presenting new long-term, quantitative late Permian (Lopingian) to Early Triassic records of dispersed fossil charcoal and inertinite from sediments of the Sydney Basin, eastern Australia. We also document little-transported fossil charcoal occurrences in middle to late Permian (Guadalupian to Lopingian) permineralized peats of the Lambert Graben, East Antarctica, and Sydney and Bowen basins, eastern Australia, indicating that even vegetation of consistently moist high-latitude settings was prone to regular fire events. Our records show that wildfires were consistently prevalent through the Lopingian, but the EPE demonstrates a clear spike in activity. The relatively low charcoal and inertinite baseline for the Early Triassic is likely due in part to the lower vegetation density, which would have limited fire spread. We review the evidence for middle Permian to Lower Triassic charcoal in the geosphere, and the impacts of wildfires on sedimentation processes and the evolution of landscapes. Moreover, we assess the evidence of continental extinction drivers during the EPE within eastern Australia, and critically evaluate the role of wildfires as a cause and consequence of ecosystem collapse. The initial intensification of the fire regime during the EPE likely played a role in the initial loss of wetland carbon sinks, and contributed to increased greenhouse gas emissions and land and freshwater ecosystem changes. However, we conclude that elevated wildfire frequency was a short-lived phenomenon; recurrent wildfire events were unlikely to be the direct cause of the subsequent long-term absence of peat-forming wetland vegetation, and the associated ‘coal gap' of the Early Triassic.

Niche shifts after island colonization spurred adaptive diversification and speciation in a cosmopolitan bird clade.

Islands have long been recognized as key contributors to biodiversity because they facilitate geographic isolation and ecological divergence from mainland ancestors. However, island colonization has traditionally been considered an evolutionary dead-end process, and its consequences for continental biodiversity remain understudied. Here, we use the evolutionary radiation of Columbiformes (i.e. pigeons and doves) to examine if ecological niche shifts on islands shaped biological diversification and community composition on continents. We show that the colonization of islands by continental, terrestrial-foraging lineages led to the exploitation of a new ecological niche (i.e. arboreal foraging). This transition towards arboreal foraging was associated with evolutionary adaptation towards a new morphological optimum. In addition, arboreal-foraging lineages of islands experienced an increase in speciation rates, which was associated with successful range expansions to other islands as well as back colonization of continents. Our results provide empirical evidence that diversification on continents can only be fully understood when studying the diversification processes that took place on islands, challenging the view of islands as mere sinks of evolutionary diversity.

Impact of Pleistocene Eustatic Fluctuations on Evolutionary Dynamics in Southeast Asian Biodiversity Hotspots.

Pleistocene climatic fluctuations (PCF) are frequently highlighted as important evolutionary engines that triggered cycles of biome expansion and contraction. Although there is ample evidence of the impact of PCF on biodiversity of continental biomes, the consequences in insular systems depend on the geology of the islands and the ecology of the taxa inhabiting them. The idiosyncratic aspects of insular systems are exemplified by the islands of the Sunda Shelf in Southeast Asia (Sundaland), where PCF-induced eustatic fluctuations had complex interactions with the geology of the region, resulting in high species diversity and endemism. Emergent land in Southeast Asia varied drastically with sea-level fluctuations during the Pleistocene. Climate-induced fluctuations in sea level caused temporary connections between insular and continental biodiversity hotspots in Southeast Asia. These exposed lands likely had freshwater drainage systems that extended between modern islands: the Paleoriver Hypothesis. Built upon the assumption that aquatic organisms are among the most suitable models to trace ancient river boundaries and fluctuations of landmass coverage, the present study aims to examine the evolutionary consequences of PCF on the dispersal of freshwater biodiversity in Southeast Asia. Time-calibrated phylogenies of DNA-delimited species were inferred for six species-rich freshwater fish genera in Southeast Asia (Clarias, Channa, Glyptothorax, Hemirhamphodon, Dermogenys, Nomorhamphus). The results highlight rampant cryptic diversity and the temporal localization of most speciation events during the Pleistocene, with 88% of speciation events occurring during this period. Diversification analyses indicate that sea-level-dependent diversification models poorly account for species proliferation patterns for all clades excepting Channa. Ancestral area estimations point to Borneo as the most likely origin for most lineages, with two waves of dispersal to Sumatra and Java during the last 5 myr. Speciation events are more frequently associated with boundaries of the paleoriver watersheds, with 60%, than islands boundaries, with 40%. In total, one-third of speciation events are inferred to have occurred within paleorivers on a single island, suggesting that habitat heterogeneity and factors other than allopatry between islands substantially affected diversification of Sundaland fishes. Our results suggest that species proliferation in Sundaland is not wholly reliant on Pleistocene sea-level fluctuations isolating populations on different islands. [Dispersal; diversification; eustatic fluctuations; freshwater fishes; insular systems; Milankovitch cycles; paleoenvironments; vicariance.].

Dissecting biodiversity in a global hotspot: Uneven dynamics of immigration and diversification within the Cape Floristic Region of South Africa

AbstractAimFragmented distributions should show immigration and diversification dynamics consistent with the predictions of island biogeography theory. We test whether this applies to the fragmented Cape fynbos vegetation.LocationSouthern Africa, Cape Floristic Region (CFR).TaxonAngiosperms, Restionaceae (restios).MethodsWe used a large occurrence dataset and environmental layers to characterize an existing regionalization and the intervals between the regions ecologically and spatially. We extended the available phylogeny for restios and inferred their historical biogeography using models implemented in BioGeoBEARS. We then measured the relative contribution of immigration and in situ speciation to the species richness of each region within the CFR. We used standard statistical methods to test the predictions of the island biogeography theory.ResultsThe area and environmental heterogeneity of the seven regions of the CFR are positively correlated with in situ speciation rate. Furthermore, more isolated areas, and areas colonized more recently, have proportionally higher immigration rates, and more central and older areas proportionally higher in situ speciation rates.Main conclusionsThe variation in immigration and diversification dynamics among the regions within the CFR is extensive and consistent with the archipelago model of island biography theory. This dynamic may contribute significantly to the diversity of the Cape flora. Such a model could be generally useful for understanding the generation and maintenance of diversity in biodiversity hotspots, and may even scale up to explain continental biodiversity.

Targeted capture to assess neutral genomic variation in the narrow-leaf hopbush across a continental biodiversity refugium

The Adelaide geosyncline, a mountainous region in central southern Australia, is purported to be an important continental refugium for Mediterranean and semi-arid Australian biota, yet few population genetic studies have been conducted to test this theory. Here, we focus on a plant species distributed widely throughout the region, the narrow-leaf hopbush, Dodonaea viscosa ssp. angustissima, and examine its genetic diversity and population structure. We used a hybrid-capture target enrichment technique to selectively sequence over 700 genes from 89 individuals across 17 sampling locations. We compared 815 single nucleotide polymorphisms among individuals and populations to investigate population genetic structure. Three distinct genetic clusters were identified; a Flinders/Gammon ranges cluster, an Eastern cluster, and a Kangaroo Island cluster. Higher genetic diversity was identified in the Flinders/Gammon Ranges cluster, indicating that this area is likely to have acted as a refugium during past climate oscillations. We discuss these findings and consider the historical range dynamics of these populations. We also provide methodological considerations for population genomics studies that aim to use novel genomic approaches (such as target capture methods) on non-model systems. The application of our findings to restoration of this species across the region are also considered.

Politics, emotion, and ideology: the reality of reserve selection for nature conservation in Australia

ABSTRACT Australia's system of conservation reserves is inadequate to conserve continental biodiversity. Reserves are small, isolated, and unrepresentative of continental ecosystems to the extent that entire groups of organisms, such as nomadic and migratory birds, are poorly conserved. The reasons for the inadequacy of the reserve system are historical and embedded in politics, emotion, and ideology. To illustrate these ideas, I describe my experiences in dealing with the politics, emotion, and ideology of reserve selection and management from the late 1960's to the early 1990's in New South Wales first as a member of the Scientific Committee advising the Minister of Lands and then as a member of the New South Wales National Parks Advisory Council. An emphasis on pristine landscapes and wildness compromised recommendations for the development of the New South Wales' reserve system. My account of events as I experienced them may be of interest to persons tracing the history of reserve selection in Austral...

Approximate Bayesian Computation Reveals the Crucial Role of Oceanic Islands for the Assembly of Continental Biodiversity.

The perceived low levels of genetic diversity, poor interspecific competitive and defensive ability, and loss of dispersal capacities of insular lineages have driven the view that oceanic islands are evolutionary dead ends. Focusing on the Atlantic bryophyte flora distributed across the archipelagos of the Azores, Madeira, the Canary Islands, Western Europe, and northwestern Africa, we used an integrative approach with species distribution modeling and population genetic analyses based on approximate Bayesian computation to determine whether this view applies to organisms with inherent high dispersal capacities. Genetic diversity was found to be higher in island than in continental populations, contributing to mounting evidence that, contrary to theoretical expectations, island populations are not necessarily genetically depauperate. Patterns of genetic variation among island and continental populations consistently fitted those simulated under a scenario of de novo foundation of continental populations from insular ancestors better than those expected if islands would represent a sink or a refugium of continental biodiversity. We, suggest that the northeastern Atlantic archipelagos have played a key role as a stepping stone for transoceanic migrants. Our results challenge the traditional notion that oceanic islands are the end of the colonization road and illustrate the significant role of oceanic islands as reservoirs of novel biodiversity for the assembly of continental floras.

The plights of African resources patenting through the lenses of the World Trade Organisation: an assessment of South Africa's rooibos tea's labyrith journey.

Just as developing states are blessed with natural resources capable of transforming their economies into a positive direction, the imposed World Trade Organisation's (WTO) mores continue to relegate them to the status of underdevelopment. The consequences of this on investment, trade and finance in Third World States (TWSs), especially Africa, are disarticulation of the economy, exploitation, disinvestment, unemployment, political instability and unavailability of relevant technology to move TWSs forward, among others. This gives rise to the politics behind Rooibos (Aspalathus linearis) patenting (a medicinal plant found only in South Africa) by various multinational corporations (MNCs). This study adopted political economy approach with emphasis on both primary and secondary sources of data collection using content analysis. There is need to adhere strictly to the issues of intellectual property rights (IPRs), geographical indications (GIs), prior informed consent (PIC), and access and sharing benefits (ASB). These have not been observed by the western states because of their economic of neo-imperialism to the disadvantage of developing states. This paper recommends that there is need for a regional regime such as African Regional Intellectual Property Organisation (ARIPO), on indigenous knowledge (IK) to patent the continental biodiversity resources.

Possible origin of stagnation and variability of earth's biodiversity.

The magnitude and variability of Earth's biodiversity have puzzled scientists ever since paleontologic fossil databases became available. We identify and study a model of interdependent species where both endogenous and exogenous impacts determine the nonstationary extinction dynamics. The framework provides an explanation for the qualitative difference of marine and continental biodiversity growth. In particular, the stagnation of marine biodiversity may result from a global transition from an imbalanced to a balanced state of the species dependency network. The predictions of our framework are in agreement with paleontologic databases.

Diversity dynamics of Miocene mammals in relation to the history of tectonism and climate

Continental biodiversity gradients result not only from ecological processes, but also from evolutionary and geohistorical processes involving biotic turnover in landscape and climatic history over millions of years. Here, we investigate the evolutionary and historical contributions to the gradient of increasing species richness with topographic complexity. We analysed a dataset of 418 fossil rodent species from western North America spanning 25 to 5 Ma. We compared diversification histories between tectonically active (Intermontane West) and quiescent (Great Plains) regions. Although diversification histories differed between the two regions, species richness, origination rate and extinction rate per million years were not systematically different over the 20 Myr interval. In the tectonically active region, the greatest increase in originations coincided with a Middle Miocene episode of intensified tectonic activity and global warming. During subsequent global cooling, species richness declined in the montane region and increased on the Great Plains. These results suggest that interactions between tectonic activity and climate change stimulate diversification in mammals. The elevational diversity gradient characteristic of modern mammalian faunas was not a persistent feature over geologic time. Rather, the Miocene rodent record suggests that the elevational diversity gradient is a transient feature arising during particular episodes of Earth's history.

Priorities for Improving the Scientific Foundation of Conservation Policy in North America

The Society for Conservation Biology (SCB) can enhance conservation of biodiversity in North America by increasing its engagement in public policy. Toward this end, the North America Section of SCB is establishing partnerships with other professional organizations in order to speak more powerfully to decision makers and taking other actions--such as increasing interaction with chapters--geared to engage members more substantively in science-policy issues. Additionally, the section is developing a North American Biodiversity Blueprint, which spans the continental United States and Canada and is informed by natural and social science. This blueprint is intended to clarify the policy challenges for protecting continental biodiversity, to foster bilateral collaboration to resolve common problems, and to suggest rational alternative policies and practices that are more likely than current practices to sustain North America's natural heritage. Conservation scientists and practitioners can play a key role by drawing policy makers' attention to ultimate, as well as proximate, causes of biodiversity decline and to the ecological and economic consequences of not addressing these threats.

Demonstration of a satellite-based index to monitor habitat at continental-scales

An important initial step in the conservation and sustainable management of the Earth's biodiversity is to implement systems to both identify and subsequently monitor components of biological diversity, along with developing a better understanding of the processes that significantly threaten their conservation or sustainable use. Key factors in both species diversity and richness are related to environmental heterogeneity which is driven by temporal and spatial variation in the biological, physical, and chemical features of the environment. These environmental characteristics are manifest through the condition and change in vegetation productivity (considered as an integrated response of vegetation to climate and soil conditions). Earth observation is uniquely capable of synoptically covering large areas of the planet in a repeatable, and cost effective manner, and is a well-established technology for detecting terrestrial vegetation productivity. A recently developed dynamic habitat index (DHI), based on satellite observations of the fraction of radiation absorbed by the canopy (fPAR), has been shown to effectively cluster remotely sensed observations into a range of habitat regimes which in turn have been related to breeding bird surveys in the Canadian Province of Ontario and across the conterminous United States. With evidence that the index is well correlated with species diversity, we consider, in this subsequent paper, whether such an index is a suitable candidate as a continental index to characterize and subsequently monitor habitat conditions. To do so, we first utilise available fPAR data available from 2000 to 2005 over North America, and apply the index. Using information on continental terrestrial ecozones and their ecological distinctiveness, we then compare and contrast the index and utilize trajectory analysis to assess what changes have occurred in the index over the 6-year time period and possible implications for continental biodiversity. The potential application of the index is the discussed.

Molecular biogeography: towards an integrated framework for conserving pan-African biodiversity.

BackgroundBiogeographic models partition ecologically similar species assemblages into discrete ecoregions. However, the history, relationship and interactions between these regions and their assemblages have rarely been explored.Methodology/Principal FindingsHere we develop a taxon-based approach that explicitly utilises molecular information to compare ecoregion history and status, which we exemplify using a continentally distributed mammalian species: the African bushbuck (Tragelaphus scriptus). We reveal unprecedented levels of genetic diversity and structure in this species and show that ecoregion biogeographic history better explains the distribution of molecular variation than phenotypic similarity or geography. We extend these data to explore ecoregion connectivity, identify core habitats and infer ecological affinities from them.Conclusions/SignificanceThis analysis defines 28 key biogeographic regions for sub-Saharan Africa, and provides a valuable framework for the incorporation of genetic and biogeographic information into a more widely applicable model for the conservation of continental biodiversity.

Conservation Challenge of Dispersive Fauna

The six papers in this theme issue of Pacific Conservation Biology were presented at a symposium organized by the WildCountry Science Council (see Recher 2003 for an account of WildCountry) at the Adelaide meeting of the Ecological Society of Australia in 2004. The symposium theme of ?dispersive fauna? is central to the philosophy and principles of WildCountry. The WildCountry philosophy is based on the argument that the long-term conservation of continental biodiversity is not possible with a system of spatially static conservation reserves by itself. Reserves form the core of WildCountry, but cannot fully sample continental biodiversity, nor allow for the full range of movements characteristic of the biota unless the total area set aside from development far exceeds what society would see as economically or politically acceptable. Because of these limits, a static and spatially limited reserve system cannot meet the challenge of ensuring the evolutionary viability of populations and species. A challenge that becomes increasingly difficult and urgent to resolve in the face of accelerating climate change and the loss and modification of habitat through land clearing, pastoralism, changed fire regimes, and the spread of weeds and feral animals among a myriad of environmental changes driven by human endeavour across the landscape. In my view, probably greater than 50% of the continent is the absolute minimum for a fixed system of reserves to meet the needs of biodiversity conservation, but see Archer (2002) who suggests a minimum of 20% may be required simply to meet the most basic evolutionary criteria.

Diversification of a large genus in a continental biodiversity hotspot: Temporal and spatial origin of Muraltia (Polygalaceae) in the Cape of South Africa

Phylogenetic relationships in the largely South African genus Muraltia (Polygalaceae) are assessed based on DNA sequence data (nuclear ribosomal ITS, plastid atpB–rbcL spacer, trnL intron, and trnL–F spacer) for 73 of the 117 currently recognized species in the genus. The previously recognised subgenus Muraltia is monophyletic, but the South African endemic genus Nylandtia is embedded in Muraltia subgenus Psiloclada. Subgenus Muraltia is found to be sister to subgenus Psiloclada. Estimates show the beginning of diversification of the two subgenera in the early Miocene ( Psiloclada, 19.3 ± 3.4 Ma; Muraltia, 21.0 ± 3.5 Ma) pre-dating the establishment of the Benguela current (intermittent in the middle to late Oligocene and markedly intensifying in the late Miocene), and summer-dry climate in the Cape region. However, the later increase in species numbers is contemporaneous with these climatic phenomena. Results of dispersal-vicariance analyses indicate that major clades in Muraltia diversified from the southwestern and northwestern Cape, where most of the species are found today.

Protected areas and the regional planning imperative in North America: integrating nature conservation and sustainable development

Regional planning is imperative if North America has any hope of retaining continental biodiversity and environmentally, socially, and economically sustainable development.Protected Areas and the Regional Planning Imperative in North Americas is a timely collection of essays presents new protected area theory, method, and practice as an explicit part of regional planning. With a North American focus, these essays consider the history of ecology, policy, and planning of protected areas in the context of the fundamental need for a linkage with ongoing regional planning. Protected areas and regional planning must be pursued, not as separate, but rather as interrelated activities if both are to achieve their place in decision-making in North America. With Contributions By: Natalie Ban Heather Black Scott Brennan Kenneth W. Cox Bruce A.B. Currie-Alder Gustavo Danemann J.C.Day Ileana Espejel Exequiel M. Ezcurra Graham Forbes BillFreedman Noel Aron Fuentes Steve Gatewood David Gauthier Christopher Gosselin Hans Hermann Jurgen Hoth Marvin O. Jensen Sabine Jessen Patrick Lawrence James Loucky Roberto Martinez Kevin McNamee John C. Miles J.G. Nelson Lina Ojeda Revah Alejando Robles Lucy Sportza Carlos Israel Vazquez Ella Vazquez-Dominquez Ed Wiken Christopher E. Williams Stephen Woodley

Opportunities for the future

IN the last issue, David Paton wrote about water rationing in Australia's largest cities and lost opportunities. The opportunities Australia passed by were those which would have avoided the need for water rationing, protected the continent's river systems from degradation, conserved continental biodiversity and contributed importantly to achieving an ecologically sustainable economy. Had Australians been prepared to work together, the opportunities missed could have been taken up at no great cost to either society or individuals. Indeed, the environmental and social benefits generated would have more than compensated for any imagined losses in productivity and income.

The past, future and present of biodiversity conservation in Australia

Australia has a poor record for biodiversity conservation. Government and community priorities promote growth and resource exploitation over conservation and ecologically sustainable land and water use. Programmes to protect biodiversity are inadequate, poorly funded, and inappropriate. Consequently, Australia has a large extinction debt and the 21st Century will see massive losses of continental biodiversity. Because birds are well known, these trends are already evident among Australia's avifauna and illustrate the magnitude of the problems facing biodiversity conservation in 21st Century Australia. Only by ending land clearing, limiting population growth, and adopting scientifically based land and water management and conservation practices can these trends be reversed. This is unlikely, as Australia's largely urban population is ill-informed, while the scientific community is marginalized and the agenda of green groups perpetuates the status quo.

Biodiversity on land and in the sea

AbstractLife on land today is as much as 25 times as diverse as life in the sea. Paradoxically, this extraordinarily high level of continental biodiversity has been achieved in a shorter time and it occupies a much smaller area of the Earth's surface than does marine biodiversity. Raw palaeontological data suggest very different models for the diversification of life on land and in the sea. The well‐studied marine fossil record appears to show evidence for an equilibrium model of diversification, with phases of rapid radiation, followed by plateaux that may indicate times of equilibrium diversity. The continental fossil record shows exponential diversification from the Silurian to the present. These differences appear to be real: the continental fossil record is unlikely to be so poor that all evidence for a high initial equilibrial diversity has been lost. In addition, it is not clear that the apparently equilibrial marine model is correct, since it is founded on studies at familial level. At species level, a logistic family‐level curve probably breaks down to an exponential. The rocketing diversification rates of flowering plants, insects, and other land life are evidently hugely different from the more sluggish rates of diversification of life in the sea, perhaps as a result of greater endemism and habitat complexity on land. Copyright © 2001 John Wiley & Sons, Ltd.