Quantitative criteria for species delimitation TOBIAS, JOSEPH A.; SEDDON, NATHALIE; SPOTTISWOODE, CLAIRE N. ...
Ibis (London, England),
October 2010, Letnik:
152, Številka:
4
Journal Article
Recenzirano
Species are the fundamental units of biology, ecology and conservation, and progress in these fields is therefore hampered by widespread taxonomic bias and uncertainty. Numerous operational ...techniques based on molecular or phenotypic data have been designed to overcome this problem, yet existing procedures remain subjective or inconsistent, particularly when applying the biological species concept. We address this issue by developing quantitative methods for a classic technique in systematic zoology, namely the use of divergence between undisputed sympatric species as a yardstick for assessing the taxonomic status of allopatric forms. We calculated mean levels of differentiation in multiple phenotypic characters – including biometrics, plumage and voice – for 58 sympatric or parapatric species‐pairs from 29 avian families. We then used estimates of mean divergence to develop criteria for species delimitation based on data‐driven thresholds. Preliminary tests show that these criteria result in relatively few changes to avian taxonomy in Europe, yet are capable of extensive reassignment of species limits in poorly known tropical regions. While we recognize that species limits are in many cases inherently arbitrary, we argue that our system can be applied to the global avifauna to deliver taxonomic decisions with a high level of objectivity, consistency and transparency.
World governments have committed to halting human-induced extinctions and safeguarding important sites for biodiversity by 2020, but the financial costs of meeting these targets are largely unknown. ...We estimate the cost of reducing the extinction risk of all globally threatened bird species (by > 1 International Union for Conservation of Nature Red List category) to be U.S. $0.875 to $1.23 billion annually over the next decade, of which 12% is currently funded. Incorporating threatened nonavian species increases this total to U.S. $3.41 to $4.76 billion annually. We estimate that protecting and effectively managing all terrestrial sites of global avian conservation significance (11,731 Important Bird Areas) would cost U.S. $ 65.1 billion annually. Adding sites for other taxa increases this to U.S. $76.1 billion annually. Meeting these targets will require conservation funding to increase by at least an order of magnitude.
Protected areas (PAs) are a cornerstone of conservation efforts and now cover nearly 13% of the world's land surface, with the world's governments committed to expand this to 17%. However, as ...biodiversity continues to decline, the effectiveness of PAs in reducing the extinction risk of species remains largely untested. We analyzed PA coverage and trends in species' extinction risk at globally significant sites for conserving birds (10,993 Important Bird Areas, IBAs) and highly threatened vertebrates and conifers (588 Alliance for Zero Extinction sites, AZEs) (referred to collectively hereafter as 'important sites'). Species occurring in important sites with greater PA coverage experienced smaller increases in extinction risk over recent decades: the increase was half as large for bird species with>50% of the IBAs at which they occur completely covered by PAs, and a third lower for birds, mammals and amphibians restricted to protected AZEs (compared with unprotected or partially protected sites). Globally, half of the important sites for biodiversity conservation remain unprotected (49% of IBAs, 51% of AZEs). While PA coverage of important sites has increased over time, the proportion of PA area covering important sites, as opposed to less important land, has declined (by 0.45-1.14% annually since 1950 for IBAs and 0.79-1.49% annually for AZEs). Thus, while appropriately located PAs may slow the rate at which species are driven towards extinction, recent PA network expansion has under-represented important sites. We conclude that better targeted expansion of PA networks would help to improve biodiversity trends.
There is an emerging consensus that protected areas are key in reducing adverse land-cover change, but their efficacy remains difficult to quantify. Many previous assessments of protected area ...effectiveness have compared changes between sets of protected and unprotected sites that differ systematically in other potentially confounding respects (e.g. altitude, accessibility), have considered only forest loss or changes at single sites, or have analysed changes derived from land-cover data of low spatial resolution. We assessed the effectiveness of protection in reducing land-cover change in Important Bird Areas (IBAs) across Africa using a dedicated visual interpretation of higher resolution satellite imagery. We compared rates of change in natural land-cover over a c. 20-year period from around 1990 at a large number of points across 45 protected IBAs to those from 48 unprotected IBAs. A matching algorithm was used to select sample points to control for potentially confounding differences between protected and unprotected IBAs. The rate of loss of natural land-cover at sample points within protected IBAs was just 42% of that at matched points in unprotected IBAs. Conversion was especially marked in forests, but protection reduced rates of forest loss by a similar relative amount. Rates of conversion increased from the centre to the edges of both protected and unprotected IBAs, but rates of loss in 20-km buffer zones surrounding protected IBAs and unprotected IBAs were similar, with no evidence of displacement of conversion from within protected areas to their immediate surrounds (leakage).
The Fifth World Parks Congress in Durban, South Africa, announced in September 2003 that the global network of protected areas now covers 11.5% of the planet's land surface. This surpasses the 10% ...target proposed a decade earlier, at the Caracas Congress, for 9 out of 14 major terrestrial biomes. Such uniform targets based on percentage of area have become deeply embedded into national and international conservation planning. Although politically expedient, the scientific basis and conservation value of these targets have been questioned. In practice, however, little is known of how to set appropriate targets, or of the extent to which the current global protected area network fulfils its goal of protecting biodiversity. Here, we combine five global data sets on the distribution of species and protected areas to provide the first global gap analysis assessing the effectiveness of protected areas in representing species diversity. We show that the global network is far from complete, and demonstrate the inadequacy of uniform-that is, 'one size fits all'-conservation targets.
Knowledge products comprise assessments of authoritative information supported by standards, governance, quality control, data, tools, and capacity building mechanisms. Considerable resources are ...dedicated to developing and maintaining knowledge products for biodiversity conservation, and they are widely used to inform policy and advise decision makers and practitioners. However, the financial cost of delivering this information is largely undocumented. We evaluated the costs and funding sources for developing and maintaining four global biodiversity and conservation knowledge products: The IUCN Red List of Threatened Species, the IUCN Red List of Ecosystems, Protected Planet, and the World Database of Key Biodiversity Areas. These are secondary data sets, built on primary data collected by extensive networks of expert contributors worldwide. We estimate that US$160 million (range: US$116-204 million), plus 293 person-years of volunteer time (range: 278-308 person-years) valued at US$ 14 million (range US$12-16 million), were invested in these four knowledge products between 1979 and 2013. More than half of this financing was provided through philanthropy, and nearly three-quarters was spent on personnel costs. The estimated annual cost of maintaining data and platforms for three of these knowledge products (excluding the IUCN Red List of Ecosystems for which annual costs were not possible to estimate for 2013) is US$6.5 million in total (range: US$6.2-6.7 million). We estimated that an additional US$114 million will be needed to reach pre-defined baselines of data coverage for all the four knowledge products, and that once achieved, annual maintenance costs will be approximately US$12 million. These costs are much lower than those to maintain many other, similarly important, global knowledge products. Ensuring that biodiversity and conservation knowledge products are sufficiently up to date, comprehensive and accurate is fundamental to inform decision-making for biodiversity conservation and sustainable development. Thus, the development and implementation of plans for sustainable long-term financing for them is critical.
World governments have committed to increase the global protected areas coverage by 2020, but the effectiveness of this commitment for protecting biodiversity depends on where new protected areas are ...located. Threshold‐ and complementarity‐based approaches have been independently used to identify important sites for biodiversity. We brought together these approaches by performing a complementarity‐based analysis of irreplaceability in important bird and biodiversity areas (IBAs), which are sites identified using a threshold‐based approach. We determined whether irreplaceability values are higher inside than outside IBAs and whether any observed difference depends on known characteristics of the IBAs. We focused on 3 regions with comprehensive IBA inventories and bird distribution atlases: Australia, southern Africa, and Europe. Irreplaceability values were significantly higher inside than outside IBAs, although differences were much smaller in Europe than elsewhere. Higher irreplaceability values in IBAs were associated with the presence and number of restricted‐range species; number of criteria under which the site was identified; and mean geographic range size of the species for which the site was identified (trigger species). In addition, IBAs were characterized by higher irreplaceability values when using proportional species representation targets, rather than fixed targets. There were broadly comparable results when measuring irreplaceability for trigger species and when considering all bird species, which indicates a good surrogacy effect of the former. Recently, the International Union for Conservation of Nature has convened a consultation to consolidate global standards for the identification of key biodiversity areas (KBAs), building from existing approaches such as IBAs. Our results informed this consultation, and in particular a proposed irreplaceability criterion that will allow the new KBA standard to draw on the strengths of both threshold‐ and complementarity‐based approaches.
Site conservation is among the most effective means to reduce global biodiversity loss. Therefore, it is critical to identify those sites where unique biodiversity must be conserved immediately. To ...this end, the concept of key biodiversity areas (KBAs) has been developed, seeking to identify and, ultimately, ensure that networks of globally important sites are safeguarded. This methodology builds up from the identification of species conservation targets (through the IUCN Red List) and nests within larger-scale conservation approaches. Sites are selected using standardized, globally applicable, threshold-based criteria, driven by the distribution and population of species that require site-level conservation. The criteria address the two key issues for setting site conservation priorities: vulnerability and irreplaceability. We also propose quantitative thresholds for the identification of KBAs meeting each criterion, based on a review of existing approaches and ecological theory to date. However, these thresholds require extensive testing, especially in aquatic systems.
Networks of sites of high importance for conservation of biological diversity are a cornerstone of current conservation strategies but are fixed in space and time. As climate change progresses, ...substantial shifts in species' ranges may transform the ecological community that can be supported at a given site. Thus, some species in an existing network may not be protected in the future or may be protected only if they can move to sites that in future provide suitable conditions. We developed an approach to determine appropriate climate-change adaptation strategies for individual sites within a network that was based on projections of future changes in the relative proportions of emigrants (species for which a site becomes climatically unsuitable), colonists (species for which a site becomes climatically suitable), and persistent species (species able to remain within a site despite the climatic change). Our approach also identifies key regions where additions to a network could enhance its future effectiveness. Using the sub-Saharan African Important Bird Area (IBA) network as a case study, we found that appropriate conservation strategies for individual sites varied widely across sub-Saharan Africa, and key regions where new sites could help increase network robustness varied in space and time. Although these results highlight the potential difficulties within any planning framework that seeks to address climate-change adaptation needs, they demonstrate that such planning frameworks are necessary, if current conservation strategies are to be adapted effectively, and feasible, if applied judiciously. Las redes de sitios de gran importancia para la conservación de la diversidad biológica son una piedra angular de las estrategias actuales de conservación pero están fijas en espacio y tiempo. A medida que el cambio climático progresa, cambios sustanciales en los rangos de distribución de las especies pueden transformar la comunidad ecológica que puede ser soportada en un sitio determinado. Por lo tanto, algunas especies en una red existente pueden no ser protegidas en el futuro o pueden ser protegidas solo si se mueven a sitios que proporcionen condiciones adecuadas en el futuro. Desarrollamos un método para determinar las estrategias de adaptación al cambio climático para sitios individuales dentro de una red que se basó en las proyecciones de cambios futuros en las proporciones relativas de emigrantes (especies para las que un sitio se vuelve inadecuado climáticamente), colonizadoras (especies para las que un sitio se vuelve adecuado climáticamente) y especies persistentes (especies capaces de permanecer en un sitio no obstante el cambio climático). Nuestro método también identifica regiones clave donde adiciones a una red podrían reforzar su efectividad en el futuro. Utilizando la red del Área de Importancia para las Aves sub-Sahariana como un caso de estudio, encontramos que las estrategias de conservación apropiadas para sitios individuales variaron ampliamente en África sub-Sahariana, y regiones clave donde nuevos sitios podrían ayudar a incrementar la robustez de la red variaron en espacio y tiempo. Aunque estos resultados resaltan las dificultades potenciales de cualquier marco de planificación que busque abordar las necesidades de adaptación al cambio climático, demuestran que tales marcos de planificación son necesarios, para que las estrategias de conservación actuales sean adaptadas efectivamente, y sean factibles, si son aplicadas juiciosamente.
PDF
