Species extinction is both a key process throughout the history of life and a pressing concern in the conservation of present-day biodiversity. These two facets have largely been studied by separate ...communities using different approaches. This article illustrates with examples some of the ways that considering the evolutionary relationships among species—phylogenies—has helped the study of both past and present species extinction. The focus is on three topics: extinction rates and severities, phylogenetic nonrandomness of extinction, and the testing of hypotheses relating extinction-proneness to attributes of organisms or species. Phylogenetic and taxic approaches to extinction have not fully fused, largely because of the difficulties of relating discrete taxa to the underlying continuity of phylogeny. Phylogeny must be considered in comparative tests of hypotheses about extinction, but care must be taken to avoid overcorrecting for phylogenetic nonindependence among taxa.
The strength of phylogenetic signal in extinction risk can give insight into the mechanisms behind species' declines. Nevertheless, no existing measure of phylogenetic pattern in a binary trait, such ...as extinction-risk status, measures signal strength in a way that can be compared among data sets. We developed a new measure for phylogenetic signal of binary traits, D, which simulations show gives robust results with data sets of more than 50 species, even when the proportion of threatened species is low. We applied D to the red-list status of British birds and the world's mammals and found that the threat status for both groups exhibited moderately strong phylogenetic clumping. We also tested the hypothesis that the phylogenetic pattern of species threatened by harvesting will be more strongly clumped than for those species threatened by either habitat loss or invasive species because the life-history traits mediating the effects of harvesting show strong evolutionary pattern. For mammals, our results supported our hypothesis; there was significant but weaker phylogenetic signal in the risk caused by the other two drivers (habitat loss and invasive species). We conclude that D is likely to be a useful measure of the strength of phylogenetic pattern in many binary traits.
Protected areas are widely considered essential for biodiversity conservation. However, few global studies have demonstrated that protection benefits a broad range of species. Here, using a new ...global biodiversity database with unprecedented geographic and taxonomic coverage, we compare four biodiversity measures at sites sampled in multiple land uses inside and outside protected areas. Globally, species richness is 10.6% higher and abundance 14.5% higher in samples taken inside protected areas compared with samples taken outside, but neither rarefaction-based richness nor endemicity differ significantly. Importantly, we show that the positive effects of protection are mostly attributable to differences in land use between protected and unprotected sites. Nonetheless, even within some human-dominated land uses, species richness and abundance are higher in protected sites. Our results reinforce the global importance of protected areas but suggest that protection does not consistently benefit species with small ranges or increase the variety of ecological niches.
Land use and related pressures have reduced local terrestrial biodiversity, but it is unclear how the magnitude of change relates to the recently proposed planetary boundary ("safe limit"). We ...estimate that land use and related pressures have already reduced local biodiversity intactness–the average proportion of natural biodiversity remaining in local ecosystems–beyond its recently proposed planetary boundary across 58.1% of the world's land surface, where 71.4% of the human population live. Biodiversity intactness within most biomes (especially grassland biomes), most biodiversity hotspots, and even some wilderness areas is inferred to be beyond the boundary. Such widespread transgression of safe limits suggests that biodiversity loss, if unchecked, will undermine efforts toward long-term sustainable development.
The island rule: made to be broken? Meiri, Shai; Cooper, Natalie; Purvis, Andy
Proceedings of the Royal Society. B, Biological sciences,
01/2008, Letnik:
275, Številka:
1631
Journal Article
Recenzirano
Odprti dostop
The island rule is a hypothesis whereby small mammals evolve larger size on islands while large insular mammals dwarf. The rule is believed to emanate from small mammals growing larger to control ...more resources and enhance metabolic efficiency, while large mammals evolve smaller size to reduce resource requirements and increase reproductive output. We show that there is no evidence for the existence of the island rule when phylogenetic comparative methods are applied to a large, high-quality dataset. Rather, there are just a few clade-specific patterns: carnivores; heteromyid rodents; and artiodactyls typically evolve smaller size on islands whereas murid rodents usually grow larger. The island rule is probably an artefact of comparing distantly related groups showing clade-specific responses to insularity. Instead of a rule, size evolution on islands is likely to be governed by the biotic and abiotic characteristics of different islands, the biology of the species in question and contingency.
Human use of the land (for agriculture and settlements) has a substantial negative effect on biodiversity globally. However, not all species are adversely affected by land use, and indeed, some ...benefit from the creation of novel habitat. Geographically rare species may be more negatively affected by land use than widespread species, but data limitations have so far prevented global multi-clade assessments of land-use effects on narrow-ranged and widespread species. We analyse a large, global database to show consistent differences in assemblage composition. Compared with natural habitat, assemblages in disturbed habitats have more widespread species on average, especially in urban areas and the tropics. All else being equal, this result means that human land use is homogenizing assemblage composition across space. Disturbed habitats show both reduced abundances of narrow-ranged species and increased abundances of widespread species. Our results are very important for biodiversity conservation because narrow-ranged species are typically at higher risk of extinction than widespread species. Furthermore, the shift to more widespread species may also affect ecosystem functioning by reducing both the contribution of rare species and the diversity of species' responses to environmental changes among local assemblages.
Human land use has caused substantial declines in global species richness. Evidence from different taxonomic groups and geographic regions suggests that land use does not equally impact all organisms ...within terrestrial ecological communities, and that different functional groups of species may respond differently. In particular, we expect large carnivores to decline more in disturbed land uses than other animal groups.
We present the first global synthesis of responses to land use across functional groups using data from a wide set of animal species, including herbivores, omnivores, carnivores, fungivores and detritivores; and ranging in body mass from 2 × 10−6 g (an oribatid mite) to 3,825 kg (the African elephant).
We show that the abundance of large endotherms, small ectotherms, carnivores and fungivores (although in the last case, not significantly) are reduced disproportionately in human land uses compared with the abundance of other functional groups.
The results, suggesting that certain functional groups are consistently favoured over others in land used by humans, imply a substantial restructuring of ecological communities. Given that different functional groups make unique contributions to ecological processes, it is likely that there will be substantial impacts on the functioning of ecosystems.
A free Plain Language Summary can be found within the Supporting Information of this article.
A free Plain Language Summary can be found within the Supporting Information of this article.
Ecological change provokes speciation and extinction, but our knowledge of the interplay among the biotic and abiotic drivers of macroevolution remains limited. Using the unparalleled fossil record ...of Cenozoic macroperforate planktonic foraminifera, we demonstrate that macroevolutionary dynamics depend on the interaction between species' ecology and the changing climate. This interplay drives diversification but differs between speciation probability and extinction risk: Speciation was more strongly shaped by diversity dependence than by climate change, whereas the reverse was true for extinction. Crucially, no single ecology was optimal in all environments, and species with distinct ecologies had significantly different probabilities of speciation and extinction. The ensuing macroevolutionary dynamics depend fundamentally on the ecological structure of species' assemblages.
While the regional distribution of non-native species is increasingly well documented for some taxa, global analyses of non-native species in local assemblages are still missing. Here, we use a ...worldwide collection of assemblages from five taxa - ants, birds, mammals, spiders and vascular plants - to assess whether the incidence, frequency and proportions of naturalised non-native species depend on type and intensity of land use. In plants, assemblages of primary vegetation are least invaded. In the other taxa, primary vegetation is among the least invaded land-use types, but one or several other types have equally low levels of occurrence, frequency and proportions of non-native species. High land use intensity is associated with higher non-native incidence and frequency in primary vegetation, while intensity effects are inconsistent for other land-use types. These findings highlight the potential dual role of unused primary vegetation in preserving native biodiversity and in conferring resistance against biological invasions.
After the launch of the Global Assessment of the Intergovernmental Platform for Biodiversity and Ecosystem Services (IPBES) in May 2019, the message that 1 million species are threatened with ...extinction made headlines in news and social media across the world. These headlines also resulted in critical responses that questioned the credibility of this number and - by extension - the Global Assessment report and the institution of IPBES. In this article, we - as two authors of the Global Assessment - draw lessons from the GA about how to represent biodiversity in assessments and how biodiversity knowledge can inform effective and legitimate actions that contribute to conservation as well as equity, justice, and human well-being. Specifically, we highlight the inherent multiplicity of meanings and definitions of biodiversity to reflect on the limitations of using species richness and extinction as proxies for biodiversity and biodiversity loss. It is crucial to communicate clearly and in a balanced way that biodiversity loss is broader than species extinction, and how this broader loss of biodiversity jeopardises human wellbeing irrespective of whether species die out. Consequently, the post-2020 biodiversity framework will require multiple targets around not only species extinction but also broader biodiversity loss and human well-being.
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