Tag Archives: species

Incompetent Invaders Dilute Parasites and Alter Disease Dynamics

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

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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Fighting Climate Change While Maintaining Biodiversity: Can It Be Done?

Mapping co-benefits for carbon storage and biodiversity to inform conservation policy and action (2019) Soto-Navarro et al., Philosophical Transactions of the Royal Society B, https://doi.org/10.1098/rstb.2019.0128

The Crux

With the world under so many anthropogenic pressures simultaneously, trying to come up with management solutions for different issues can be a problem. Climate change and biodiversity are a great example. Storing carbon is a great way to reduce the effects of climate change, and increasing the range of forests worldwide is a great way to increase carbon storage. Yet the sort of forests that store carbon most efficiently are often poor at promoting biodiversity. They are largely made up of very similar trees, while forests that include brush, scrubs, and other layers often store less carbon, but house more biodiverse communities.

As such, finding areas that are prime specimens for a) storing carbon and b) biodiversity conservation are incredibly important, so that managers at every level (from park rangers right up to the Intergovernmental Panel on Climate Change) can know where interests overlap, and adjust plans accordingly.

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Bringing Wild Mammals to the Classroom: The MammalWeb Program

Image Credit: Lazy Daisie, CC BY-SA 3.0, Image Cropped

There’s a certain age you hit when you just can’t name your third favourite mammal anymore. I often quietly pray that the day my kid stops asking weird questions about animal snot never comes, but I know it’s probably not far off. That eagerness to learn at a young age, especially about animals, is what ecologist Sammy Mason has managed to tap into over the last two years of her PhD.

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Investigating the Small Island Effect

Image Credit: Dmitry Teslya, CC BY 2.0, Image Cropped

Species-area relationships on small islands differ among plant growth forms (2020) Schrader et al., Global Ecology and Biogeography, https://doi.org/10.1111/geb.13056

The Crux

We’ve talked a lot about Island Biogeography Theory (IBT) in the last couple of weeks. One of the key tenets, established way back in the 60s, is that as an island’s area decreases, its species richness tends to as well. Yet since IBT was conceptualised, there have been a number of amendments made to it. The Small Island Effect (SIE) is one of them.

SIE essentially means that below a certain threshold (called a ‘breakpoint’), species stop obeying that species richness to area relationship. This week’s researchers wanted to test whether that breakpoint was different between species groups, and whether the species area relationship changed below that breakpoint, or simply disappeared.

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Should We Conserve Hybrids?

Image Credit: Carol M. Highsmith, CC BY 2.0, Image Cropped

The ultimate goal of species conservation is to preserve a species’ existence in the natural world. To effectively do this, we must know the extent of “species” that we want to conserve. That may sound simple, but the concept of hybridisation can blur the lines of where one species begins and another ends beyond recognition.

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Bigger is Not Always Better in Habitat Conservation

Whilst Island Biogeography Theory originally led many to believe that larger, more connected patches of habitat are more important for species conservation, new research suggests that overlooking smaller patches could be dangerous (Image Credit: LuxTonnerre, CC BY 2.0, Image Cropped)

Global synthesis of conservation studies reveals the importance of small habitat patches for biodiversity (2019) Wintle et al., PNAS, https://doi.org/10.1073/pnas.1813051115

The Crux

Human land use over the past millenia has divided species habitats into smaller and smaller patches – a practice which often leaves conservationists with the tough choice of which remaining patches they should focus their efforts on. Traditional practice has seen the prioritisation of large patches that are well connected to other, with this preference often meaning that smaller more isolated patches are neglected, and often cleared.

This week’s paper authors wanted to check whether this was really the best way of doing things, by looking at the relative conservation value of a variety of habitat patches.

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