Category Archives: Paper of the Week

Measuring the Popularity of North American Birds

The largest owl in North America, the Snowy Owl. New research shows that this individuals size may help with his popularity among us humans, but his lack of colour might not (Image Credit: USFWS Mountain-Prairie, CC BY 2.0, Image Cropped)

Characterizing the cultural niches of North American birds (2019) Schuetz & Johnston, PNAS, https://doi.org/10.1073/pnas.1820670116

The Crux

For all our attempts to maintain objectivity in science, often the reality is that the more people value a bird species, the more likely our conservation efforts are to be successful through public support. As such, figuring out which birds are popular, and where, could give us some crucial information on where we’ll need to fight hardest to help species persist, and where our efforts at science communication could use some work.

This week we look at a novel paper that tries to assess which types of North American birds are popular with the public, and whether that popularity is confined only to their home states, or whether it is shown in surrounding areas as well.

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The Varying Roles of Indigenous, Government, and Private Protected Areas in Conservation

The Gawler Ranges, an area of Indigenous protected land in South Australia (Image Credit: Korkut Tas, CC BY-SA 3.0, Image Cropped)

Differences among protected area governance types matter for conserving vegetation communities at-risk of loss and fragmentation (2020) Archibald et al., Biological Conservation, 247, https://doi.org/10.1016/j.biocon.2020.108533

The Crux

The designation of Protected Areas (PAs) has been a key tool in the fight to retain biodiversity and restore ecosystems globally. Designating a region as protected goes a long way to ensuring the survival of a wide rage of species, both locally and on much larger scales. In recent decades, private PAs have been growing in number, and on top of that, 7.8 million squared kilometres worldwide are now registered as Indigenous PAs. As a result, conservation goals are often formed with all three types of protected area in mind.

There has been ample research showing that all three types of PA have been effective in conserving wildlife and habitat types. But all three have different characteristics, both in governance and allocation. Today’s authors wanted to find out whether they protected different types of habitat, and what that could mean for conservation policy going forward.

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Where the Wild Things Are

Urban aliens and threatened near-naturals: Land-cover affects the species richness of alien- and threatened species in an urban- rural setting (2020), Petersen et al., Scientific Reports, https://doi.org/10.1038/s41598-020-65459-2

The Crux

Land-use changes (in particular, urbanisation and everything related to it) have huge effects on biodiversity patterns – some habitats can support populations of many different species, others cannot. This seems intuitive on a large scale (think a rainforest vs. a large, industrialised city) and on a small scale (a small patch of concrete vs. a patch of soil in a forest), but what about on a medium scale, more relevant to management organisations? How different species of plants, animals and fungi are distributed in space on such a meso-scale is far more relevant to everyday management, compared to say a global distribution, or the organisation of a 10 x 10 metre quadrant.

Today’s authors (myself and my current supervisors) looked at how species richness changes with land-cover on a municipality scale. We also looked at whether these patterns differ if one considers the total number of species, threatened- or alien ones, and whether animals, plants and fungi react to concrete vs. forests in the same way.

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Radar vs. Optical: Optimising Satellite Use in Land Cover Classification

An optical image of Kliuchevskoi volcano on the left, with a radar image on the left (Image credit: Michigan Tech Volcanology, Image Cropped)

Improving the accuracy of land cover classification in cloud persistent areas using optical and radar satellite image time series (2020), Lopes et al., Methods in Ecology and Evolution, https://doi.org/10.1111/2041-210X.13359

The Crux

Most ecologist has at some point run across or used a land cover map in their career. Whether it’s used for figuring out the canopy diversity of a forest, or figuring out which habitat a species is using, land cover maps are incredibly useful tools for everyone from conservationists to architects. But have you ever wondered how they are produced?

Until recently, land cover maps were created using either images from optical satellites or images from radar satellites with a coarse to medium spatial resolution (check out the Did You Know Section for more details, or the image above for an example). Combined with classification algorithms, land cover maps can be created automatically. That makes it sound simple, but the final output depends greatly on the quality and amount of images you use for the classification. Since 2014, the Copernicus Programme has made satellite imaginary freely available at high spatial and temporal spatial resolution. Due to this, optical and radar images can be combined more efficiently to produce land cover classification maps with enhanced accuracy. This is especially useful in tropical and boreal areas, as optical images often don’t show the entire landscape due to persistent cloud over.

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Don’t Compete If You Don’t Want to Get Eat(en)

Image Credit: Judy Gallagher, CC BY 2.0, Image Cropped

Predators weaken prey intraspecific competition through phenotypic selection (2020) Siepielski, Hasik et al., Ecology Letters, https://doi.org/10.1111/ele.13491

The Crux

We are all familiar with predator-prey relationships in nature, those in which one organism (a predator) kills and consumes another (the prey). Besides these direct effects on prey via consumption, predators can also impose indirect effects on their prey. An indirect effect is one in which the predator changes some aspect of the prey, such as their behavior or the way that they look, but these changes are brought about just by the predator being around. These predator-mediated effects are known to affect the relationships between prey organisms themselves, such as how prey organisms compete with one another, whether its for food, mates, or other resources.

Predators are known to affect how active their prey are, and this selection on activity results in a trade-off between how much prey can grow and their risk of predation. Being more active can allow you to find and eat more food, but that also means that a potential predator is more likely to see you. Today’s paper used larval damselflies and their fish predators to study how selection of fish on their damselfly prey based on the damselfly activity rates affected competition between the damselflies.

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On Moose Who Reproduce: To Use Or Not To Use

Guest post by Endre Grüner Ofstad

Opposing fitness consequences of habitat use in a harvested moose population (2019) Ofstad, Markussen at al., Journal of Animal Ecology, https://doi.org/10.1111/1365-2656.13221

The Crux

At the heart of our understanding of animal behaviour is Optimal Foraging Theory. It’s related to the core concepts of population ecology, and essentially asks which life history trait a species is more concerned with – survival or reproduction. For instance, often for a herbivore, the areas where they will find the most food is also the area where the most predators will be lurking. This presents them with two options – eat lots, reproduce a lot, and die young, or eat less, reproduce less (at least per year) and live longer.

On a species level we can compare mice and elephants. Yet these differences also occur within species and populations. Some individuals are more prone to high-risk strategies, while others prefer the low-risk strategy. Which strategy is the best will depend on the prevailing environment. For instance, a situation with few predators (or hunters) will favour the more risk-prone strategy, while a strong presence of predators will favour the risk-averse strategy. Populations who experience environmental variations are expected to have a composition of strategies that varies accordingly. 

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Using eDNA to Avoid Being Eaten on the Job

Image Credit: pxfuel, CC0 1.0, Image Cropped

Monitoring the silver carp invasion in Africa: a case study using environmental DNA (eDNA) in dangerous watersheds (2020) Crookes et al., NeoBiota, http://doi.org/10.3897/neobiota.56.47475

The Crux

One thing the last two months have taught us all is that testing for a problem is crucial. The earlier you catch a problem, the more of a chance you have to stop that problem spreading. Coronavirus is one example, invasive species is another. Detecting an invader arriving early on means you can potentially remove it before it has become properly established, saving millions of dollars down the line.

But often testing isn’t practical. Take freshwater environments. Sometimes a river may be hard to get to. Sometimes it may be infested with crocodiles and hippos. Makes regular testing methods like electrofishing or gillnetting a bit tricky.

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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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Protection from Two Enemies with One Defense

Image Credit: Connor Long, CC BY-NC-SA 3.0, Image Cropped

Of poisons and parasites—the defensive role of tetrodotoxin against infections in newts (2018) Johnson et al., Journal of Animal Ecology, https://doi.org/10.1111/1365-2656.12816

The Crux

Many organisms in nature produce powerful (and sometimes deadly) toxic substances, often taken as evidence that prey evolved chemical defenses against predators. Interestingly, these chemical defenses are deadly not only to predators, but also to parasites. This complementary defense, in addition to the ubiquity of parasites themselves, indicate that parasites may have had a hand in the evolution of host toxicity.

One particularly potent toxin found in the animal kingdom is tetrodotoxin (TTX). It can cause paralysis, difficulty with breathing, and even death in some cases. Newts in the genus Taricha are notorious for having high concentrations of TTX in their skin and eggs, and this has long been thought to have evolved as a defense against predators. In particular, Taricha newts and garter snakes (Thamnopholis spp.) are a classic example of arms-race dynamics (see Did You Know). Despite this relationship, newt toxicity and snake resistance to the toxin don’t always match up perfectly in nature, suggesting that other factors may influence newt toxicitiy. The goal of today’s study was to study parasitic infection and compare it to variation in toxicity among two newt species, the rough-skinned newt (T. granulosa) and the California newt (T. torosa).

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