Scientists' warning to humanity on insect extinctions

A review of the relation between species traits and extinction risk

Biological records are one of the most important sources of data for a large number of research areas. For example, their application has made valuable contributions to climate change ecology, where they are used to monitor species range shifts; to conservation ecology, where they are used to assess species' Red List status; and to biogeography, where they are used to highlight hotspots of biodiversity. A major benefit of biological records is the large spatial extent of the coverage combined with the fine spatial precision of the data: this combination is essential for any ecologist hoping to address large-scale questions about biodiversity and environmental change. Because most biological records are collected by a vast pool of volunteer recorders, studies utilizing biological records have the advantage of large-scale long-term data that it would otherwise be unfeasibly expensive to collect. We review the application of biological records by focussing on four key areas of biodiversity research: biogeography, trend assessments, climate change ecology, and conservation biology. We showcase the diversity of insights that biological records have delivered, which in turn illustrates the contribution of the voluntary recording community to our understanding of biodiversity science.

Beyond maps: a review of the applications of biological records

Here, we determine annual estimates of occupancy and species trends for 5,293 UK bryophytes, lichens, and invertebrates, providing national scale information on UK biodiversity change for 31 taxonomic groups for the time period 1970 to 2015. The dataset was produced through the application of a Bayesian occupancy modelling framework to species occurrence records supplied by 29 national recording schemes or societies (n = 24,118,549 records). In the UK, annual measures of species status from fine scale data (e.g. 1 × 1 km) had previously been limited to a few taxa for which structured monitoring data are available, mainly birds, butterflies, bats and a subset of moth species. By using an occupancy modelling framework designed for use with relatively low recording intensity data, we have been able to estimate species trends and generate annual estimates of occupancy for taxa where annual trend estimates and status were previously limited or unknown at this scale. These data broaden our knowledge of UK biodiversity and can be used to investigate variation in and drivers of biodiversity change. Machine-accessible metadata file describing the reported data: https://doi.org/10.6084/m9.figshare.9977426

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Annual estimates of occupancy for bryophytes, lichens and invertebrates in the UK, 1970–2015

Despite claims of an insect decline worldwide, our understanding of extinction risk in insects is incomplete. Using bionomic data of all odonate (603 dragonflies and damselflies) North American species, we assessed (i) regional extinction risk and whether this is related to local extirpation; (ii) whether these two patterns are similar altitudinally and latitudinally; and (iii) the areas of conservation concern. We used geographic range size as a predictor of regional extinction risk and body size, thermal limits and habitat association as predictors of local extirpation. We found that (i) greater regional extinction risk is related to narrow thermal limits, lotic habitat use and large body size (this in damselflies but not dragonflies); (ii) southern species are more climate tolerant but with more limited geographic range size than northern species; and (iii) two priority areas for odonate conservation are the cold temperate to sub-boreal northeastern USA and the transversal neo-volcanic system. Our approach can be used to estimate insect extinction risk as it compensates for the lack of abundance data.

https://royalsocietypublishing.org/doi/pdf/10.1098/rspb.2019.2645

Why do bugs perish? Range size and local vulnerability traits as surrogates of Odonata extinction risk.

A major challenge in ecology is understanding why certain species persist, while others decline, in response to environmental change. Trait-based comparative analyses are useful in this regard as they can help identify the key drivers of decline, and highlight traits that promote resistance to change. Despite their popularity trait-based comparative analyses tend to focus on explaining variation in range shift and extinction risk, seldom being applied to actual measures of species decline. Furthermore they have tended to be taxonomically restricted to birds, mammals, plants and butterflies. Here we utilise a novel approach to estimate occurrence trends for the Odonata in Britain and Ireland, and examine trait correlates of these trends using a recently available trait dataset. We found the dragonfly fauna in Britain and Ireland has undergone considerable change between 1980 and 2012, with 22 and 53% of species declining and increasing, respectively. Distribution region, habitat specialism and range size were the key traits associated with these trends, where habitat generalists that occupy southern Britain tend to have increased in comparison to the declining narrow-ranged specialist species. In combination with previous evidence, we conclude that the lower trend estimates for the narrow-ranged specialists could be a sign of biotic homogenization with ecological specialists being replaced by warm-adapted generalists.

Dave Smallshire

Papers

Trait correlates of distribution trends in the Odonata of Britain and Ireland.

Trait correlates of distribution trends in the Odonata of Britain and Ireland: Southern species benefit from climate warming