Cartoon guide to biodiversity loss LXIII

26 10 2020

The sixth set of biodiversity cartoons for 2020. See full stock of previous ‘Cartoon guide to biodiversity loss’ compendia here.

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Spread of harmful species despite early warnings

12 10 2020

The goal of developing an alien-species warning system is to remove the species locally and to allow others enough time to take actions that prevent further spread.

For the green iguana (Iguana iguana) however, its > 50-year spread around the globe continues as we show in our latest study by using citizen-science data. We demonstrate how pet owners and recreational parks have facilitated the green iguana’s spread to mainland Asia, and project its potential future Asian range in the absence of immediate actions.

Do you know how best to deal with an invasive species? Avoid them in the first place.

There is broad agreement among scientists and conservation practitioners that the first line of defense against invasive species is prevention. Once established, invasive species can cause agricultural damage, compete with native species for space, become predators, or carry with them and introduce new diseases. We’ve seen this time and again, with some infamous examples including zebra mussels in the Great Lakes of North America (1), cane toads in Australia (2), and Asian tiger mosquitoes around the world (3). 

To stop the list of invasive species from growing, it is important to detect spreading and newly arriving species early, ideally before they become established. Early detection is especially evident for green iguanas, given their high rates of population growth (females can lay up to 70 eggs), although detectability can be particularly challenging in forested spaces.

Two green iguanas reported on iNaturalist in Jurong Bird Park, Singapore. Free-roaming green iguanas could escape the limits of parks and become a source of new populations throughout Asia. Picture Credit: user pseudomonasry. Used under a Creative Commons licence.

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Grand Challenges in Global Biodiversity Threats

8 10 2020

Last week I mentioned that the new journal Frontiers in Conservation Science is now open for business. As promised, I wrote a short article outlining our vision for the Global Biodiversity Threats section of the journal. It’s open-access, of course, so I’m also copying here on

Most conservation research and its applications tend to happen most frequently at reasonably fine spatial and temporal scales — for example, mesocosm experiments, single-species population viability analyses, recovery plans, patch-level restoration approaches, site-specific biodiversity surveys, et cetera. Yet, at the other end of the scale spectrum, there have been many overviews of biodiversity loss and degradation, accompanied by the development of multinational policy recommendations to encourage more sustainable decision making at lower levels of sovereign governance (e.g., national, subnational).

Yet truly global research in conservation science is fact comparatively rare, as poignantly demonstrated by the debates surrounding the evidence for and measurement of planetary tipping points (Barnosky et al., 2012; Brook et al., 2013; Lenton, 2013). Apart from the planetary scale of human-driven disruption to Earth’s climate system (Lenton, 2011), both scientific evidence and policy levers tend to be applied most often at finer, more tractable research and administrative scales. But as the massive ecological footprint of humanity has grown exponentially over the last century (, robust, truly global-scale evidence of our damage to the biosphere is now starting to emerge (Díaz et al., 2019). Consequently, our responses to these planet-wide phenomena must also become more global in scope.

Conservation scientists are adept at chronicling patterns and trends — from the thousands of vertebrate surveys indicating an average reduction of 68% in the numbers of individuals in populations since the 1970s (WWF, 2020), to global estimates of modern extinction rates (Ceballos and Ehrlich, 2002; Pimm et al., 2014; Ceballos et al., 2015; Ceballos et al., 2017), future models of co-extinction cascades (Strona and Bradshaw, 2018), the negative consequences of invasive species across the planet (Simberloff et al., 2013; Diagne et al., 2020), discussions surrounding the evidence for the collapse of insect populations (Goulson, 2019; Komonen et al., 2019; Sánchez-Bayo and Wyckhuys, 2019; Cardoso et al., 2020; Crossley et al., 2020), the threats to soil biodiversity (Orgiazzi et al., 2016), and the ubiquity of plastic pollution (Beaumont et al., 2019) and other toxic substances (Cribb, 2014), to name only some of the major themes in global conservation. 

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