Tag Archives: extinction

We’re In The Sixth Mass Extinction Event

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Image Credit: Bernard Dupont, CC BY-SA 2.0, Image Cropped

The urgency behind the most recent IPCC report has thankfully garnered it a lot of attention worldwide*. It’s a report that was very frank in its desperation for people to take this threat as seriously as possible. Yet both this report and the one that hit us in February also made mention of one other key factor that has been swept under the rug – the ability of functioning ecosystems to both mediate and mitigate the impact of climate change.

Alongside a wealth of other benefits we gain from biodiversity, ecosystems play vital roles in helping us withstand the rigours of climate change. Wetlands and rivers protect us from increased flooding. Forests help mitigate extreme heat waves. Peatlands, mires, and permafrost are all crucial carbon sinks. Yet as species disappear, these ecosystems deteriorate, as pieces of the complicated web that they’re made up of disappear. It’s why the concept of mass extinction is so frightening.

But what is mass extinction? We often hear about the concept of a mass extinction, and the question of whether we’re currently in the sixth mass extinction is constantly thrown around. So let’s have a quick look at exactly what extinction itself means, what a mass extinction is, and why it’s increasingly obvious that we’re in one.

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Good News In Case Environmental Anxiety Has You Down

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Image Credit: Peter Trimming, CC BY 2.0, Image Cropped

With the constant deluge of environmental disasters and newly endangered or extinct species, it’s sometimes easy to think there is only ever bad news when it comes to nature. But there is good news lurking out there, and it’s a source of hope, inspiration and action for many. So let’s have a look at some success stories from the past month.

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Wilderness: A Place of Untouched Ecological Processes

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Image Credit: European Wilderness Society, CC BY 4.0, Image Cropped

What comes to your mind when you think of Wilderness? Maybe it is a dense rainforest filled with a cacophony of bird calls, or plain filled with lagre grazing animals and free-roaming carnivores? They certainly qualify, but by definition, Wilderness is any area that hasn’t (or has only slightly) been modified by human activity in the past. This means that Wilderness areas can be incredibly diverse, from the aforementioned tropical forest to a murky swamp. These areas represent nature in its purest form, with the absence of human interventions allowing for dynamic, open-ended natural processes. These processes not only create marvelous landscapes and offer refuge for species, but also provide many benefits for humans.

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The How and Why of Climate-Mediated Extinction

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Image Credit: Dreamy Pixel, CC BY 4.0

Recent responses to climate change reveal the drivers of species extinction and survival (2020) Román-Palacios & Wiens, PNAS, https:/doi/10.1073/pnas.1913007117

The Crux

We tend to think of climate change as bad, and despite the fact that some organisms will benefit from it, many others won’t. A big part of why we consider it bad is that species are predicted to be lost at an alarming rate, with some estimates as high as 54% of all organisms going extinct. An issue with these predictions is that they tend to assume that species will track their preferred temperature and precipitation conditions, but this eliminates any ability of organisms to adapt to their new normal over time.

Today’s authors wanted to use data from previous studies to estimate how species adapt (or don’t) to climate change. Although previous work has shown that climate change is detrimental for many species, this study aimed to learn if it was due to changes in the overall temperature, changes in the extremes (i.e. how hot the hottest day is), or was it the sheer speed of change that did organisms in. Read more

Worrying Trends in North America’s Bird Populations

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Birds like this American tree sparrow are declining rapidly, shows a study which looks at huge declines in North American bird populations

Birds like this American tree sparrow are declining rapidly, shows a study which looks at huge declines in North American bird populations (Image Credit: Ryan Hodnett, CC BY-SA 4.0, Image Cropped)

Decline of the North American avifauna (2019) Rosenberg et al., Science, DOI: 10.1126/science.aaw1313

The Crux

When we talk about species loss, we generally focus on extinctions. Too often, when we start to rally around a species, it’s because there are a particularly low number of that species left. In many cases, they’ve often crossed a threshold, from which it’s impossible to pull them back from the brink of extinction.

Often this draws attention away from non-threatened species. Often that’s fine – they’re non-threatened right? But downward population trajectories in these species can still damage ecosystems by lessening the impact of their ecological function, lead to local (if not total) extinctions, and of course, leading them to eventually be threatened.

This week’s authors wanted to look at bird population declines in America, but from the perspective of total abundance, as opposed to a more species-specific view.

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Brains Over Brawn

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Image Credit: Kevin Pluck, CC BY 2.0, Image Cropped

Brain expansion in early hominins predicts carnivore extinctions in East Africa (2020) Faurby et al, Ecology Letters, https://doi.org/10.1111/ele.13451

The Crux

We’ve covered humans and their harmful effects many times here on Ecology for the Masses (see my recent breakdown from last month). Despite all of the colorful examples of our current effects on the wildlife of our planet, a significant amount of research has implicated Homo sapiens as the driver of the extinction of some of the megafauna of the prehistoric world, events that happens millions of years ago. Another possibility is that we as organisms (hominins, not Homo sapiens specifically) have been impacting other species for a very, very long time.

Today, East Africa is home to the most diverse group of large carnivores on the planet (though it is still less diverse than what was once seen in North America and Eurasia). Millions of years ago East Africa had an even more diverse assemblage of large carnivores, including bears, dogs, giant otters, and saber-toothed cats. The change in climate since that time may have caused the decline in large carnivore diversity, but another explanation is the rise of early hominins (our ancestors). Using fossil data, the authors of today’s paper wanted to figure out if it was indeed early hominins that drove many large carnivores extinct.

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What Being Functionally Extinct Means, Why Koalas Aren’t, and Why Things Are Still Pretty Dire

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Image Credit: Swallowtail Grass Seeds, Public Domain Mark 1.0, Image Cropped

There has been a lot of recent (and well deserved) press surrounding the bush fires in Australia. Because of these fires countless animal and plant life has been lost, and the most visible example of that are the koalas. You probably saw the video of a woman running into a burning area to save a koala from the fire*. Unfortunately, most of the koalas didn’t have people around to save them and over 1,000 are estimated to have died. Because of this a group has claimed that koalas are now “functionally extinct”, and the press has run with this claim. While it is unfortunate that this misinformation spread so quickly and so widely, the good news is that koalas are in fact NOT functionally extinct. Great! But what does being “functionally extinct” mean? 

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Outdoor Cats are a Problem

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Outdoor cats are a contentious issue for cat-owners, cat-lovers, and those that are concerned about the environment. Like it or not, Fluffy is doing a LOT of damage (Image credit: Cat Outside in Sweden-148884.jpg by Jonatan Svensson Glad, CC BY-SA 4.0, Image Cropped).

I hate to be the bearer of bad news, but domestic cats are bad for the environment. Sure, we as a species have adopted and incorporated them into our society (I live with two, myself), but that doesn’t mean we aren’t responsible for them and their actions.

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Simulating the Evolution of Life in South America

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Image Credit: johnno49, Pixabay licence, Image Cropped

Modeling the ecology and evolution of biodiversity: Biogeographical cradles, museums, and graves (2018) Rangel et al., Science, 244, DOI: 10.1126/science.aar5452

The Crux

Understanding the processes which drive biodiversity worldwide is never more crucial than now, in a world where biodiversity is shrinking rapidly. Biogeography, the study of species distributions, has come a long way, but there are still a lot of problems that need solving, including improving our understanding of the interactions between factors like climate change, dispersal abilities, fragmentation and species competition, to name a few.

This paper attempted to analyse some of the effects of those factors in concert, by producing a simulation of the evolutionary process in the world’s most biologically diverse continent, South America.

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Restoring Biodiversity Through Species Interactions

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When species like this toucanet are lost, the interactions that they are a part of are lost too. So how can we restore them? (Image Credit: Jairmoreirafotografia, CC BY-SA 4.0, Image Cropped)

Estimating interaction credit for trophic rewilding in tropical forests (2018) Marjakangas, E.-L. et al., Philosophical Transactions of the Royal Society of Biology, 373, https://dx.doi/10.1098/rstb.2017.0435

The Crux

We have reviewed more than enough papers on biodiversity loss to entitle us to skip the whole “losing species is bad” spiel (see here, here and here). But what we haven’t talked about is that when some species are lost, specific interactions that those species participate in disappear from an ecosystem. Those interactions range from the minute to the crucial. One such crucial example is that of seed dispersal, whereby specific plants rely on specific animals to disperse their seeds, thus maximising biodiversity in other parts of the forest and creating a positive feedback loop.

Naturally, conservationists will want to reintroduce animals to propagate some of these reactions. But as is always the case in conservation, maximising return is absolutely essential when you’re faced with limited resources and a lot of ground to cover. Today’s authors wanted to develop a system for maximising the effect of species reintroduction.

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