Tag Archives: climate

A role for biotic interactions in limiting species’ range limits

Biotic interactions are more often important at species’ warm versus cool range edges (2021) Paquette & Hargreaves, Ecology Letters, https://doi.org/10.1111/ele.13864

Image credit: Malonecr7, CC BY-SA 3.0, via Wikimedia Commons, image cropped

The Crux

In the natural world, most organisms are limited by the environment as to where they can live. While this can be as drastic as a whale being limited to the ocean and humans being limited to the land, there are also more subtle limitations. That is, black and grizzly bears live in temperate environments, but polar bears are inhabit the arctic where it is MUCH colder. Due to the limitations imposed by the environment, black and grizzly bears cannot live further north.

Historically, most studies have focused on abiotic variables (i.e., non-living), like temperature and precipitation, as there is a clear role for the climate in determining where and when a species can live. However, biotic variables (i.e., living) like predation or competition can also play a role in defining the limits of a species range, though this has proven more difficult to test than abiotic factors, as many tests of biotic variables produce species-specific results. Charles Darwin proposed a framework in 1859 that the importance of biotic interactions would vary predictably with latitude and elevation. That is, at cooler, high-altitude locations abiotic interactions would be more important, while biotic interactions would be more important at warmer, low-altitude locations. Although a number of studies have attempted to test the three predictions (see Did You Know? ) derived from this framework, the results are contradictory and come from data testing different predictions using different data. Today’s authors sought to test all three predictions at once in order to resolve these contradictory results.

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Polar bears are the poster child of the Arctic, and under serious threat thanks climate change and the reduction of the polar ice caps. But one person’s loss is another one’s gain, and due to warming temperatures case grizzly bears are able to move further north as the icy conditions (and soft, blubbery seals – the preferred food source for polar bears) recede. This means that grizzlies and polar bears are more likely to come into contact with each other and (interestingly) are able to hybridise and produce a pizzly (or grolar) bear.

Interestingly, and unlike most hybrids, pizzly bears are quite robust (having traits of both parents mean they are likely able to exploit the habitats and food sources of both species) and able to produce viable offspring as shown in a study from 2017 that used genetic analysis to determine ancestry. They found some polar-grizzly hybrids to be 75:25 grizzly:polar bear, which means that one parent (in this case the mother) was a polar-grizzly hybrid to begin with.

As the likelihood of grizzlies and polars coming into contact with each other increases, we expect the number of hybrids in the population to increase as well. This won’t be the first time that these two species interbreed but it does still pose an interesting question of how we view ‘species’, as well as how we would approach hybrids in terms of conservation. Are we okay with polar-grizzly hybrids? Do we see them as a new species or simply an unwanted side effect of species range shifts? Do we view the northward-moving grizzlies as invasive?

Read more: Recent Hybridization between a Polar Bear and Grizzly Bears in the Canadian Arctic

Tanya Strydom is a PhD candidate at the Université de Montréal, mostly focusing on how we can use machine learning and artificial intelligence in ecology. Current research interests include (but are not limited to) predicting ecological networks, the role species traits and scale in ecological networks, general computer (and maths) geekiness, and a (seemingly) ever growing list of side projects. Tweets (sometimes related to actual science) can be found @TanyaS_08.

Mussel Mass

Facilitation alters climate change risk on rocky shores (2022) Jurgens et al. 2022, Ecology, https://doi.org/10.1002/ecy.3596

Image credit: Paul Asman and Jill Lenoble, CC BY 2.0, Image Cropped

The Crux

Climate change has a marked effect on the environment, and in most cases will be (and already is) devastating to natural systems. However, some areas (and the organisms within them) are less vulnerable to harm than others. Biogenic habitats, or habitats created by a given species which reduce physical stress for other species that live in them (more in Did You Know?), are predicted to reduce the harmful effects of climate change. In particular, they can reduce heat and desiccation.

There have been an abundance of studies on the positive effects of biogenic habitats, but little has been done to explore if these habitats can provide protection against climate change. Today’s authors utilized a marine system to understand how biogenic habitats respond to climate change, allowing for predictions of what will happen to these systems.

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Zoochory (the dispersal of seeds by animals) is pretty important for a lot of plant species. Many plants have evolved to depend on it, and it allows them to get their seeds from A to B, especially over long distances. When plants no longer have their animal buddies to move their seeds around, they aren’t going to be going anywhere fast.

With an uptick in human induced extinctions and the general movement of animals in response to climate change (who at least have the option to pack up their things and move to where the grass is greener), a lot of plants could end up getting left behind. This means that not only are they losing out on the normal dispersal processes but they’re also missing out on a potential ride to more suitable areas as their habitat conditions begin to decline – a bit of a double whammy really.

Read More: The effects of defaunation on plants’ capacity to track climate change

Tanya Strydom is a PhD student at the Université de Montréal, mostly focusing on how we can use machine learning and artificial intelligence in ecology. Current research interests include (but are not limited to) predicting ecological networks, the role species traits and scale in ecological networks, general computer (and maths) geekiness, and a (seemingly) ever growing list of side projects. Tweets (sometimes related to actual science) can be found @TanyaS_08.

Getting The Most Out Of A Jigsaw Ecosystem

Image Credit: Mainaksinghabarma, CC BY-SA 4.0, Image Cropped

Increasing cover of natural areas at smaller scales can improve the provision of biodiversity and ecosystem services in agroecological mosaic landscapes (2022) Rosenfield et al., Journal of Environmental Management, https://doi.org/10.1016/j.jenvman.2021.114248

The Crux

While nature documentaries insist on portraying the natural world as entirely separate from human life, the fact is that ‘natural’ areas exist side by side with, and often within a mosaic of, human and semi-human (think agricultural or grazed) ecosystems. These natural ecosystems provide a wide array of services – they hold biodiversity, suck carbon in from the atmosphere, maintain clean water, and even regulate local temperatures.

With a growing global population, maintaining these ecosystems unfortunately isn’t as simple as leaving the natural world alone. Development needs to be planned with these ecosystems in mind, and choosing exactly where to leave them intact is tricky. Scale is a big problem here – does leaving one big patch of forest untouched give the same benefits as leaving many smaller patches dotted throughout a landscape? That’s what today’s researchers were trying to answer.

What They Did

Today’s researchers studied a large region in south-west Ontario, Canada. The region contained a number of different ecosystems, which they broke into natural, agricultural, and urban areas. They selected regions across the different areas to test for different indicators of ecosystem services:

  • Biodiversity – in this case the abundance and species richness of different plant species
  • Carbon storage – in this case measured by the mass of trees above ground throughout the regions
  • Local climate regulation – the ability of an ecosystem to regulate local temperatures
  • Water quality – checking the concentration of different minerals in local water sources

They then compared these to the percentage of these regions which were covered by natural, agricultural, or urban areas.

Did You Know: Cultural Landscapes

Large agricultural clearance often creates fragmented landscapes and damages population which depends on large, connected landscapes. Yet at a small scale, very localised grazing often create small patches that break up the usual landscape and can sometimes increase species richness on a larger scale. It’s a phenomenon that has often led the idea of ‘cultural landscapes’ being deemed necessary for a healthy landscape. Yet often these landscapes are a fairly recent phenomenon, and not really representative of the ‘natural state’ of an ecosystem. Furthermore, they may increase species richness on a small scale, but if they expand too much those effects start to be outweighed by their fragmenting effects.

What They Found

The most notable patterns came with an increase in natural land cover. Where there were higher proportion of natural land, biodiversity increased and local temperature decreased at all spatial scales. Aboveground carbon and water quality also increased with increasing natural land, though only at smaller scales.

Increasing urban land area led to lower biodiversity and higher temperatures across all scales, while the only pronounced effect an increase in agricultural land had was to decrease local temperatures.


Obviously a high level of plant species richness does not necessarily translate to high species richness of other organisms like fungi and animals. Species richness itself can be misleading, as high abundances of one particular species and small abundances of others will give the same value as a more even spread across the region. However, a more intensive survey would have increased the workload tenfold, and I understand why the authors went for plant diversity, which generally can be a good indicator for more comprehensive estimates.

So What

While there are many who argue for the positive influence of agricultural areas on the environment, this study suggests that natural ecosystems are by far the most important contributors to important ecosystem services. The fact that this was even more pronounced on smaller spatial scales means that a mosaic-like spread of natural areas throughout a landscape is beneficial, rather than isolated patches of forest dotted throughout larger areas.

These are important notes for environmental planners, who need to be considering exactly where agricultural areas (and further urban encroachment) should lie in the future. Ecosystems provide us with a host of tangible benefits, and we need to preserve these, not to mention the bevy of species that exist within them.

Dr. Sam Perrin is a freshwater ecologist who completed his PhD at the Norwegian University of Science and Technology and will quite happily go for long walks in the forest in order to skip work and say he “got lost”. You can read more about his research and the rest of the Ecology for the Masses writers here, see more of his work at Ecology for the Masses here, or follow him on Twitter here.

Don’t Look Up Isn’t A Perfect Climate Change Film. The Lord of the Rings Is.

Come on Frodo, drop those fossil fuel subsidies (Image Credit: The Lord of the Rings: The Return of the King, New Line Cinema, 2003)

Regardless of your opinions on it, Don’t Look Up got people talking. The latest in a line of apocalyptic climate movies, will this be the one to effect change? I think we need more climate movies, but ones that are powerful, that stick with you after the Twitter hashtags vanish, films that embed themselves in our cultural consciousness. Maybe one like…

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Giving A Voice To The High Seas

A hydrozoan jellyfish (Crossoto sp.) observed during the NOAA Deepwater Exploration of the Marianas expedition in 2016 and filmed at a depth of around 3700m. (Image Credit: NOAA Ocean Exploration & Research, CC BY-SA 2.0, Image cropped)

With the publication of the new IPCC climate report, I am once again asking myself: What can I do to mitigate the problems that our world is facing? Climate breakdown, pollution, loss of wildlife… our planet suffers from humans’ greed, selfishness and destructive exploitation. It seems almost impossible for one to have any influence or power for change. Global and political action is the only way to tackle the drastic and life-defining challenges that we and future generations will be confronted with. 

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Good News In Case Watching the Ocean Burn Got You Depressed

Image Credit: U.S. Fish and Wildlife Service Headquarters, CC BY 2.0, Image Cropped

It’s been an awful week for the environment. If you’ve missed some of the news from the past four or five days, congratulations. But since climate-related depression is a very real thing, and there ARE always some success stories out there regarding the climate and our planet’s biodiversity, I thought I’d take this chance to share some positive stories from around the world.

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Crossing the River Between Fishers and Fish Science

"We need the next generation of scientists to be at the coalface, communicating good scientific information."

This article was first published in late 2018 (Image Credit: Mallee Catchment Management Authority, CC BY-SA 4.0, Image Cropped)

When a food source provides almost half a planet with protein, you can expect the people who deliver that food source to play an important role in society. Fishing is no exception. Any country that has a marine or freshwater ecosystem in close proximity will have a fishing community, and that community can play a variety of roles, from something as simple as putting food on people’s tables to campaigning heavily to keep your country from joining the EU.

So it makes sense that fishers should have access to good fish science, at every level. If you’re a multi-million-dollar corporation, you need to know how fish stocks will respond to certain catch levels over a sustained period. If you’re a local or specialised fishing community, you need to know how available your catch will be in five years given temperature increases. And if you’re one person on a boat in a river, you might want to know how best to treat an over- or under-sized fish to ensure it survives being released.

It follows, then, that there should be open communication between fish scientists and fishers. At this year’s Australian Society of Fish Biology conference, I asked a variety of delegates a simple question: Is there open communication?

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Extreme Climate Events: Is There A Silver Lining?

Image Credit: Wikipedia Commons, CC BY-SA 3.0, Image Cropped

The silver lining of extreme events (2018) Coleman & Wernberg, Trends in Ecology and Evolution, https://doi.org/10.1016/j.tree.2020.08.013

The Crux

We here at Ecology for the Masses recognize the harm of climate change and the danger that it poses to countless species the world over. Part of climate change involves extreme climate events such as floods, droughts, unusual cold spells, or cyclones, all of which can be devastating to natural systems. By and large these events are seen as negative, and rightfully so! But today’s paper offers another perspective on extreme climate events: their potential for driving evolution towards increased resilience.

Now, I’m not saying that these extreme climate events are good. I dislike them just as much as the next person with a shred of concern about the natural world. That being said, the authors raise some interesting points about the evidence that exists for these events being a positive force for evolution and adaptation. As such, I want to touch on a few of those points, address some issues with this ‘silver lining’, and talk about what it means going forward.

What Evidence Exists

Extreme climate events result in massive losses of organic life, local extinctions, and can drive range shifts. This is quite costly from not only an ecological point of view, but also a social and and an economic one. Due to these costs, a significant amount of effort and money has been dedicated to working on issues associated with these events. Interestingly enough, despite the negative connotations and costs associated with extreme climate events, there is emerging empirical evidence for a “benefit” in that they can cause non-random mortality (see Did You Know?), driving rapid evolution and adaptation.

Scientific theory has predicted that when extreme climate events occur in such a way that they select against weak individuals, but aren’t so extreme that “tougher” individuals cannot live, then these more tolerant and stronger individuals can persist in populations/areas undergoing extreme events. If these tougher individuals can pass on their genes, then a population can rapidly adapt to these extreme conditions. For example, a study showed that a severe cold snap selected for cold tolerance in green anoles (Anolis carolinensis), and similar work has shown that heatwaves selected for thermal tolerance in kelp. While plenty of the lizards/kelp didn’t have the proper traits to survive these extreme temperatures, some of them did. And because they passed on those genes to the next generation, the population is better-suited to survive future extreme temperatures.

Did You Know: Non-Random Mortality

Evolution is a fact of life, and the driving force behind the persistence of life on our planet. However, what you may not know is how evolution actually results in changes in a population/species over time. Individual organisms don’t evolve, species do. So how does that work? Well, it all has to do with how often certain individuals pass on their genes. “Survival of the fittest” refers to the biological concept of “fitness”, which is how good a given organism is at passing on its genes. So in order to be the most fit, you have to pass on the most genetic material, relative to other members of the population. This is where non-random mortality comes into play. Non-random mortality means that there is a pattern behind the death rates. Put into other words, the individuals that survived had something that the ones that died did not. This is how evolution works slowly over time, non-random mortality means that individuals with a given trait tend to die less often than those that don’t have that trait, which means that that trait gets passed on more often than others. Eventually, that trait will become the new normal for that population/species, and evolution has occurred.

What This Means

The potential for extreme events to select for resilience and drive rapid adaptation means that groups dedicated to conservation and preservation of species and ecosystems may be able to proactively anticipate future events. The authors highlight the difficulty inherent in studying non-model organisms for traits/genes that may promote persistence to future climate events, as it involves a LOT of background research to understand the mechanisms behind such persistence. However, to use the anoles from earlier as an example, there are better ways. If one was to go to an area that recently suffered a cold snap like those anoles did and collect the survivors, chances are that most of those survivors have the cold-tolerance trait. By selectively breeding/relocating those survivors conservation workers could prevent future die-offs due to cold snaps.

Problems With These Approaches

This all sounds great, right? No issue? Well, not quite. Just because a given trait may promote persistence to one stressor (the environment) does not mean that it promotes persistence to all others (like disease). Another issue with this silver-lining of adaptation and rapid evolution is the bottleneck effect: extreme events cause mass die-offs. Though the survivors may have a trait that allows them to persist in extreme events, the reduced population size of the survivors may result in such a marked decrease in genetic diversity that the population fails eventually anyway due to the issues associated with inbreeding.

The cheetah is an example of an organism that underwent a population bottleneck, and as such now suffers from very low levels of genetic diversity (Image credit: Ken Blum, CC BY-SA 3.0)

So What?

Extreme climate events are an unfortunate reality, and they are only predicted to get worse and become more frequent. Today’s paper offers a pleasant silver lining to that very grim reality, as it highlights the potential for these events to drive evolution and selection to extreme conditions. It may not be as good as not having these events in the first place, but the authors bring up an important point by drawing attention to the evidence that exists for populations adapting to these extreme conditions, many of which seem to be driven by human-induced climate change. I’ve recently re-read Michael Crichton’s Jurassic Park, and I can’t help but think of a quote from the character Dr. Ian Malcolm’s as I was reading this paper: “The planet has survived everything, in its time. It will certainly survive us”.

Adam Hasik is an evolutionary ecologist interested in the ecological and evolutionary dynamics of host-parasite interactions. You can read more about his research and his work for Ecology for the Masses here, see his personal website here, or follow him on Twitter here.

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