Tag Archives: invasive

Incompetent Invaders Dilute Parasites and Alter Disease Dynamics

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Guest post by Paula Tierney

Invasive freshwater fish (Leuciscus leuciscus) acts as a sink for a parasite of native brown trout Salmo trutta (2020) Tierney et al. Biological Invasions. https://doi.org/10.1007/s10530-020-02253-1

The Crux

From house cats to cane toads, invasive species are one of the biggest threats worldwide to native plants and wildlife, second only to habitat destruction. There are a few different definitions of an invasive species, but two consistent tenets are a) that they are a living organism spreading and forming new populations outside of their native range and b) causing some kind of damage to the native ecosystem, economy or human health. As humans move around the globe with increasing ease (these last two months aside), the spreading of invasive species is increasingly common in our globalised world.

The spread of invasive species creates new ecological interactions between native and invasive species that can impact how our native ecosystems function, including disease dynamics. One key set of interactions that can be completely changed by the introduction of the invader are that of parasites and their hosts. If development and transmission of native parasites is different in invasive hosts compared to their usual native hosts, the parasite dynamics of the whole system can be altered.

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Introduced Species Might Restore Ecological Functions Lost During The Ice Age

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Image Credit: hbieser, Pixabay Licence, Image Cropped

Introduced herbivores restore Late Pleistocene ecological functions (2020) Lundgren et al., PNAS, https://doi.org/10.1073/pnas.1915769117

The Crux

The fauna of the Pleistocene (also known as the Ice Age) was not that dissimilar to the communities of animals which inhabit our planet now. However, many more large land mammals inhabited all kinds of ecosystems. By the end of the Pleistocene, many of them were extinct, mainly due to climate change impacts (glaciers got larger and restricted their ragne) and prehistoric human impacts like over-hunting, habitat alteration, and introduction of new diseases. The decline of large-bodied herbivores in the Late Pleistocene (LP from here on) led to many ecological changes including reduced nutrient cycling and dispersal, reduced primary productivity, increased wildfire frequency and intensity, and altered vegetation structure. These changes have become our norm.

Scientists usually study species introduction under the premise that they are ecologically novel. However, the introduction of large herbivores has been found to drive changes in the environment, potentially restoring or introducing novel ecological functions similar to pre-extinction Late Pleistocene conditions. This week’s researchers wanted to investigate what sort of role introduced mammals played in restoring ecological interactions by investigating their functional similarity with LP species.

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The 2020 Oikos Write-Up: Ecology in the Anthropocene

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My lord Iceland is gorgeous. There could not have been a better setting for the 2020 Nordic Oikos Society’s Annual Meeting. Driving through deserts of snow that ring of the kind of quiet isolation you’d expect from a town in a depressing British murder mystery was a wonderful experience.

As was the conference itself, of course. So let’s recap some of my highlights from this year’s meeting, titled ‘Ecology in the Anthropocene’.

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Biological Invasions & The Witcher

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Image Credit: The Witcher, 2020

Science and movies often don’t go well together*. It’s no-one’s fault. Science can often be boring and riddled with uncertainties, and movies and TV require plot advancement and definitive results.

But you know what’s a scientific fact? That Henry Cavill’s chin can cut diamond, and if you thrust him into a cosplay outift he probably already had at home and send him out to slaughter a bunch of CGI monsters you’ll get something that is at the very least mildly enjoyable. And if you’re an invasion ecologist who runs a podcast looking at the ecology of movie monsters, mildly enjoyable monsters are enough to dedicate a blog post to.

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Water-Based Recreation Can Promote Non-Native Introductions

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Image Credit: Manfred Antranias Zimmer, Pixabay licence, Image Cropped

Invasion of freshwater ecosystems is promoted by network connectivity to hotspots of human activity (2019) Chapman et al., Global Ecology and Biogeography, https://doi.org/10.1111/geb.13051

The Crux

The spread of invasive species throughout freshwater ecosystems is a topic we’ve looked at before on Ecology for the Masses. In a previous paper breakdown we talked about how recreational is heavily responsible for the presence of non-native fish at a European scale.

Our paper this week takes a more local approach. Can we predict the presence of non-native birds, invertebrates and fish by looking at the presence of human activity, and where that human activity is present?

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Ecology at its Most Hectic: The 2019 BES Write-Up

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I am completely exhausted as I write this. I’ve just flown back into Norway after spending the week in Belfast at the British Ecological Society’s annual meeting. And whilst I do love attending conferences, after any mental onslaught of information it’s probably a good idea to take a day or two off to relax and let it soak in.

But before I run off on holidays to do that, let’s have a look at some of the most noteworthy points from BES 2019. I’ll touch on the words of some of the plenary speakers, the general atmosphere and I will try MY ABSOLUTE HARDEST not to talk about British politics.

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Fishing for Invaders

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Image Credit: California Department of Fish and Wildlife, CC BY 2.0, Image Cropped

Angling as a source of non-native freshwater fish: a European review (2019) Carpio, De Miguel, Oteros, Hillstrom & Tortosa, Biological Invasions, doi.org/10.1007/s10530-019-02042-5

The Crux

People love fishing. It’s an intrinsic part of some people’s lives, whether as a livelihood or a past-time. People who have grown up fishing often have specific species that they enjoy fishing for. Nothing wrong with that.

Yet people’s desire to go after one fish species will often lead them to move that species around. This can happen on a small scale, with people moving a species from one lake to another slightly closer to their homes. Or it can happen on a massive one, with a species being transported to new continents.

This has shaped entire freshwater communities in modern-day Europe, where 195 species now reside that have no natural range in the continent. Most of these have been introduced since the nineteenth century, which is around the time that fishing became a popular recreational activity. This week’s authors wanted to find out what the role of recreational fishing was in shaping the make-up of today’s invasive freshwater fish populations in Europe.

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Climate Change: Don’t Forget About the Plants!

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When we think of global warming, we tend to be a bit selfish and think of how it affects us in our daily lives, but the warming temperatures on our planet have the potential to affect the base of all of our food webs, plants (Image Credit: Matt Lavin, CC BY-SA 2.0).

Phenology in a warming world: differences between native and non-native plant species (2019) Zettlemoyer et al., Ecology Letters, https://dx.doi.org/10.1111/ele.13290

The Crux

The timing of life-history events (such as births, growing seasons, or reproductive period) is called “phenology”, and this aspect of an organism’s life is particularly sensitive to climate change. So much so that changes in the phenology of certain processes are often used as an indicator of climate change and how it affects a given organism.

We’ve talked about the effects of rising temperatures in animals here on Ecology for the Masses, but there is a lot of evidence in the scientific literature for climate change causing a multitude of different changes in the phenology of various plants. Not only does the direction of the change differ (some organisms experience delays in certain events, others have earlier starts), but the size, or magnitude, of the change also differs. The authors of today’s study wanted to examine these changes in the context of an invasive plant species and how it may be able to outcompete a native plant.
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Killing 2 Million Cats: When Broad Targets Aren’t Enough

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Image Credit: Joey Doll, CC BY 2.0, Image Cropped

Conservation or politics? Australia’s target to kill 2 million cats (2019) Doherty et al., Conservation Letters, https://doi.org/10.1111/conl.12633

The Crux

We’ve talked a lot lately about competition between causes on Ecology for the Masses. Often when extra attention is given to one cause over another equally valid cause, it’s a product of social trends coinciding at the right time, sudden events capturing the public interest (think the Notre Dame fire) or a particularly effective marketing campaign. But sometimes a cause or a conservation target can be used to deliberately distract the public from another cause, and it’s a potential example of this that we’re looking at today.

Australia has long had an issue with cats. They’ve decimated populations of native species, playing a large hand in the extinction of many species found nowhere else. So it makes sense that part of Australia’s first Threatened Species Strategy would be to minimise the impact of cat populations on local wildlife. The strategy included a target of 2 million cats being killed between 2015 and 2020. Whilst this might sound like a reasonable goal, this paper argues that the actual scientific evidence supporting the target is pretty weak, and goes into some alternatives and motives.

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Biodiverse Gardens: Where Doing Less is More

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Kiftsgate Court Garden: The Wild Garden 1. An example of a “wild garden” in the UK, where the plants have been left to grow (Image Credit: Michael Garlick, CC BY-SA 2.0, Image Cropped)

How do you make your garden more biodiversity-friendly? During my time at the  Futurum exhibition at The Big Challenge Science Festival, I spent a lot of time talking to people who expressed a desire to be manage their gardens for more plants and animals, but were unsure where to start. So I’ve compiled a brief guide on what to do, and it’s your lucky day – it involves not doing anything.

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