Tag Archives: connectivity

Bad Neighbors

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The disruption of a keystone interaction erodes pollination and seed dispersal networks, Vitali et al., 2021 Ecology. https://doi.org/10.1002/ecy.3547

Image credit: Ennio Nasi, CC BY 4.0

The Crux

Ecological communities are incredibly complex networks, made up of interactions between the species that reside in them. To properly understand how these interactions shape a community, researchers have to employ a variety of analytical methods and modelling approaches. This was something that I had to learn to appreciate in my work, because I always thought that studying ecology would involve a lot of time outdoors working with animals. While that does happen (and I spent months outside during my PhD), most of the ecological research I’m familiar with centers on math and statistics.

Using math and statistics to model ecological communities helps us to break down how various organisms are connected with one another. For example, keystone species are organisms that are connected to so many others within a given ecosystem such that any change to their populations will have consequences for the entire community. Understanding the processes that affect these keystone individuals (and all of the organisms linked to them) is vital to predicting how processes such as climate change and invasive species will affect natural communities in the future.

Today’s authors investigated how disruption of an important species interaction affected pollination and seed dispersal networks in Patagonia. A hummingbird species (Sephanoides sephaniodes) is the main pollinator for a mistletoe species (Tristerix corym-bosus), while the mistletoe provides the hummingbird with nectar in the winter. The colocolo opossum (Dromiciops gliroides) is a small marsupial that is vital for the mistletoe, as mistletoe seeds must pass through the opossum’s gut to trigger their germination. Additionally, the opossums defecate many seeds on branches in a “necklace” arrangement, which likely helps the mistletoe to parasitize their plant hosts. These three species are tightly connected to one another, and any reduction in abundance for one species may affect the other two, and even destroy the entire food web.

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On Dispersal, Connectivity and the Will of the Fish

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Image Credit: Dennis Jarvis, CC BY-SA 2.0, Image Cropped

Integrating dispersal along freshwater systems in species distribution models (2020) Perrin et. al., Diversity & Distributions, https://doi.org/10.1111/ddi.13112

The Crux

Trying to figure out where a species can comfortably live is one thing, but figuring out which habitats they can actually access is another. I like to think most marsupials would do quite well in South America or Africa, but the fact is that they’re not dispersing across the Atlantic or Pacific anytime soon. However a Species Distribution Model (a statistical model that can be used to predict the likelihood of a species being found somewhere) often requires a more nuanced approach than “big ocean separating these two habitats”.

To integrate a species’ ability to actually access an area into a Species Distributions Model (SDM), we often use the concept of connectivity. Often, this means simply measuring the distance between two populations. But sometimes a species ability to disperse might not reflect something as simple as how far it needs to go. A perfectly good habitat might be only 100 metres away, but cut off by a raging great cliff. Or a road.

In this study, we wanted to see whether we could relate connectivity parameters used in an SDM to the actual ability of the species to disperse.

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On Fish Dispersal and the Perpetual Evil of the Duck

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Image Credit: Norbert Nagel, CC BY-SA 3.0, Image Credit

Woe betide my fishy ancestors, for I am come here today to vent my grievances at a paper so dastardly it has cast a tepid patina of anxiety on a LOT of the structured squabbling my colleagues and I call ‘research’.

Actually, I shouldn’t vent too harshly on the sarcopterygiites, those ancient lobe-finned ancestors of ours and their close cousins the regular fish. Birds, as always, are the main culprit here. An abhorrent series of mutations that messed up a perfectly good reptile.

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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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How Does Our Interpretation Of Urbanisation Affect How Damaging It Is?

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Increased urbanisation may have a negative effect on the richness of moth species like this Vine’s Rustic, but it depends on what scale we consider richness (Image Credit: Patrick Clement, CC BY 2.0, Image Cropped)

Urbanization drives cross-taxon declines in abundance and diversity at multiple spatial scales (2019) Piano et al., Global Change Biology, https://doi.org/10.1111/gcb.14934

The Crux

You would think that the effect of building a whole lot of stuff on something’s habitat would have a negative effect on just about anything. But building a whole lot of human stuff (maybe let’s retain a modicum of science-ness and call it urbanisation) hasn’t always been shown to be necessarily bad for species. There are a lot of studies out there which show that urbanisation is can be a negative for biodiversity (which makes sense, since for starters it generally breaks up habitat patches and introduces a whole lot more pollutants). But there are also studies showing that urbanisation can increase biodiversity.

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Frivillig vern sin rolle i naturvern

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Image Credit: Endre Grüner Ofstad, CC BY-SA 2.0, Image Cropped

Guest post by Endre Grüner Ofstad.

Privately protected areas provide key opportunities for the regional persistence of large‐ and medium‐sized mammals (2018) Clements et al., Journal of Applied Ecology, 56(3), https://doi.org/10.1111/1365-2664.13300

Det Essensielle

Da mennesker slo seg ned i nye områder, bosatte de seg som regel i de mest produktive og artsrike områdene. I dag, mange år senere, er disse områdene fortsatt produktive og i private hender. I dag, derimot, blir flere og flere arter utrydningstruet og vi iverksetter tiltak for å redusere tapet av arter. Et av disse tiltakene er verneområder. Verneområder er områder som er satt til side for å sikre tilstedeværelse av gitte arter eller naturtyper ved å begrense høsting eller annen menneskelig innflytelse. Utfordringen er at dette ofte er kostbart da disse artsrike områdene ofte overlapper med områder som har viktige jordbruk- eller andre naturressursinteresser. Dette resulterer i at vernede områder ofte blir lagt til økonomisk marginale og/eller statseide områder. For å kontre dette kan en inkludere områder tilbudt frivillig av grunneiere. Spørsmålet blir da, hva er verneverdien av de områdene som blir tilbudt? Dette er spørsmålet som Clements og medforfatterne spør seg når jobber med Cape Floraregion i Sør-Afrika .

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The Role of Private Property in Conservation

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Image Credit: Endre Grüner Ofstad,CC BY-SA 2.0, Image Cropped

Guest post by Endre Grüner Ofstad. Norwegian version available here.

Privately protected areas provide key opportunities for the regional persistence of large‐ and medium‐sized mammals (2018) Clements et al., Journal of Applied Ecology, 56(3), https://doi.org/10.1111/1365-2664.13300

The Crux

When humans settle down in new areas, they usually settled in the most productive and species-rich areas. Now, years later, these productive areas are usually still productive, but often still in private hands. However, today more and more species are facing extinction, and many would be helped by the protection of these areas. Protected areas are areas that are set aside to ensure the viability of certain species by limiting human exploitation of the local natural resources. However, this might be costly, and these hot-spot areas likely overlap with agricultural or other natural resource exploitations, with the result that protected areas are often located to economical marginal and state-owned lands. To counter this, one might include lands offered voluntarily by private owners. But are the lands they’re offering of any conservation value?

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Keep Your Eyes Open

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Image Credit: ulleo, Pixabay licence, Image Cropped

Natural selection favors a larger eye in response to increased competition in natural populations of a vertebrate (2019) Beston & Walsh, Functional Ecology, doi: 10.1111/1365-2435.13334

The Crux

Studying the evolution of traits in response to selection pressure often helps us understand why species look and act the way they do. Selection pressure can include the need to find food before other members of your species, or the need to escape predation.

But what happens when improving your ability to obtain resources also means you’re more vulnerable to predation? Which will win out? This paper looks at a small species of freshwater fish, Rivulus hartii, and determines which of the two pressures contributes most to the evolution of the size of their eye.

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Shannon McCauley: The Rise of Community Ecology

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"...there’s been huge growth in what we can do, but I think there’s been some loss in understanding the behavioural base of biology." (Image Credit: Shannon McCauley)

Image Credit: Shannon McCauley, CC BY-SA 2.0, Image Cropped

Community ecology is one of the more recent ecological disciplines, and has enjoyed a rise in popularity in the last decade. Yet it’s often been criticised as a little obscure, and has had difficulties integrating with other branches of ecology like evolution and population dynamics.

With this in mind, I sat down with Doctor Shannon McCauley of the University of Toronto during her recent visit to the University of Arkansas. Shannon is a community ecologist at the University of Toronto-Mississauga who uses dragonflies and other aquatic insects to answer questions about dispersal, community connectivity, and the effects of climate change. We attempted to put a little more context behind community ecology, and highlighted its relevance in the coming years.

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When the Food Comes to You

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A young orca from the southern population chasing its dinner. (Image Credit: JC Winkler, CC BY 2.0, Image Cropped)

Long-distance migration of prey synchronizes demographic rates of top predators across broad spatial scales (2016) Ward et al, Ecosphere, DOI: https://doi.org/10.1002/ecs2.1276

The Crux

Populations that experience some kind of connection are classified as “meta-populations”, as they are all interconnected in some way and can influence one another. Although these populations may be geographically and reproductively isolated, meaning that they are in different places and the organisms from the different populations don’t breed with one another, certain environmental factors may cause these populations to grow or shrink in similar ways.

The key to understanding how this synchrony between the varying populations happens is understanding what connects them. Killer whale (orca) populations in the northeast Pacific Ocean inhabit three distinct areas, with orcas from the northern and southern populations never coming into contact with one another. They do, however, feed on the same salmon populations that migrate from where the southern population lives to the where the northern lives. The authors wanted to find out if this connection via a food source could result in the demographic rates of these distant populations syncing up.

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