Reducing the rate of alien species introductions is a major conservation aim. However, accurately quantifying the rate at which species are introduced into new regions remains a challenge due to the confounding effect of observation efforts on discovery records. Despite the recognition of this issue, most analyses are still based on raw discovery records, leading to biased inferences. In this study, we evaluate different models for estimating introduction rates, including new models that use auxiliary data on observation effort, and identify their strengths and weaknesses.
We compare four models: (1) a naïve model which assumes perfect detection; (2) a model proposed by Solow and Costello (the S&C model); (3) constant detection model: a modified version of the S&C model with constant detection probabilities and (4) a novel sampling proxy model: a model that uses external data on observation effort. We simulate discovery records of varying lengths, introduction rates and temporal patterns of detection probabilities to explore scenarios under which these models accurately estimate underlying introduction rates. (5) We also include code to perform a model based on Belmaker using independent data on the number of native species.
We found that the length of the discovery records and the annual number of recorded species play a crucial role in the performance of all models. Under simulated scenarios of high detection, the naïve model is usually the best-performing model, but it falls short when detection is low. Moreover, we find that in simulations which most likely mimic most real-world cases (i.e. non-monotonic probability of detection), incorporating external data on observation effort using the sampling proxy model, substantially improve estimates. This highlights the importance of considering observation effort when estimating introduction rates of alien species. To facilitate the use of these models, we provide a decision workflow and a dedicated R package (‘alien’).
Global change factors, such as warming, heatwaves, droughts and land-use changes, are intensifying fire regimes (defined here as increasing frequency or severity of fires) in many ecosystems worldwide. A large body of local-scale research has shown that such intensified fire regimes can greatly impact on ecosystem structure and function through altering plant communities. Here, we aim to find general patterns of plant responses to intensified fire regimes across climates, habitats and fire regimes at the global scale.
Worldwide.
Studies published 1962–2023.
Woody plants, herbs and bryophytes.
We carried out a global systematic review and meta-analysis of the response of plant abundance, diversity and fitness to increased fire frequency or severity. To assess the context dependency of those responses, we tested the effect of the following variables: fire regime component (fire frequency or severity), time since the last fire, fire type (wildfire or prescribed fire), historical fire regime type (surface or crown fire), plant life form (woody plant, herb or bryophyte), habitat type and climate.
Intensified fire regimes reduced overall plant abundance (Hedges' d = −0.24), diversity (d = −0.27), and fitness (d = −0.69). Generally, adverse effects of intensified fire regimes on plants were stronger due to increased severity than frequency, in wildfires compared to prescribed fires, and at shorter times since fire. Adverse effects were also stronger for woody plants than for herbs, and in conifer and mixed forests than in open ecosystems (e.g. grasslands and shrublands).
Intensified fire regimes can substantially alter plant communities in many ecosystems worldwide. Plant responses are influenced by the specific fire regime component that is changing and by the biotic and abiotic conditions.
Understanding how extinction has occurred in the recent past is crucial to unravel its main drivers as well as to implement effective conservation practices to minimize global biodiversity loss. It has long been hypothesized that extinction risk is not randomly distributed among traits of species. However, the actual traits making species more prone to extinction may have been overlooked because already extinct species are often not considered in comparative analyses of extinction risk. We characterized the drivers of extinction in a cosmopolitan bird clade, including Holocene and contemporary extinctions potentially related to human impacts and provided evidence of an ‘extinction selectivity’ in species traits.
Global.
Anthropocene.
Columbiformes clade, pigeons and doves.
We constructed a new phylogenetic hypothesis of the Columbiformes, a cosmopolitan bird clade consisting of 33 recently extinct and 351 extant species. Then, we integrated data on geography, behaviour and morphology to reveal the drivers of extinction risk. We used phylogenetic generalized least square models to test the effect of geography, behaviour and morphology in the risk of extinction and identified differences in the drivers of extinction when including versus excluding recently extinct species.
Our analysis revealed that Columbiformes endemic to islands with ground-foraging habits, weak flying abilities, migratory behaviour and larger body sizes are more vulnerable to extinction. Our results also show that excluding recently extinct species identifies extinction drivers different from those when including recently extinct species.
Only by accurately identifying the traits that increase extinction risk we can develop targeted conservation measures that promote the long-term persistence of threatened species. Extinction selectivity has important implications for the conservation of biological communities and ultimately ecosystem functioning, considering the critical role Columbiformes often play as seed dispersers.
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：