Tag Archives: dispersal

On Fish Dispersal and the Perpetual Evil of the Duck

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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The Hitchhiker’s Guide to the Herbivore

Image Credit: Jorg Hempel, CC BY-SA 2.0

Can plant traits predict seed dispersal probability via red deer guts, fur, and hooves? (2019) Petersen and Bruun, Ecology and Evolution, https://doi.org/10.1002/ece3.5512

The Crux

Large animals are key players in structuring both the physical structure and the species compositions of plant communities. They eat some plants, but not others, they trample vegetation, they deposit nutrients through feces. However, they can also affect plant communities by transporting seeds (a process called zoochory) – either by eating them and defecating later on or by acting as vehicles for seeds stuck in their fur or on their feet. As large plant eaters are found in most of the world, and several populations are actually increasing, a deeper insight into these processes could turn out to be of great importance.

Today’s authors (myself and former colleague Hans Henrik Bruun) looked at the transport of plant seeds by red deer in Denmark: whether the different kinds of seed dispersal are significantly different with regards to what species are transported, and if certain plant and seed traits can be used to predict whether a seed is more likely to be found on the outside or inside of a deer.

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Using eDNA to Monitor Fish Dispersal

Environmental DNA is a hot topic in biomonitoring. But what is it exactly, and how can it be used to monitor the dispersal of a reintroduced fish species? (Image credit: Gunnar Jacobs, CC BY-SA 2.0, Image Cropped).

Guest post by Christopher Hempel

Using environmental DNA to monitor the reintroduction success of the Rhine sculpin (Cottus rhenanus) in a restored stream (2019) Hempel et al., PeerJ, https://peerj.com/preprints/27574/

The Crux

The term “environmental DNA (eDNA)” is currently booming in molecular ecology. But what exactly is this technological marvel? Essentially, eDNA comprises all DNA released by organisms into their environment, and originates from mucus, scales, faeces, epidermal cells, saliva, urine, hair, feathers – basically anything an organism might get rid of during its life. The eDNA can be collected from the environment, extracted, and analyzed to detect species using molecular approaches. As this is a very sensitive and non-invasive approach, it is a very hot topic for biomonitoring.

eDNA can be collected from any animal (in theory), but aquatic organisms in particular have been shown to be good target individuals (as eDNA is easiest to handle in water samples). Consequently, there are many studies using eDNA to monitor the activity of fish, reaching from the presence of invasive species to the effects of aquaculture. Here, we applied eDNA analysis to monitor a reintroduced fish species, the Rhine sculpin. The sculpin’s poor swimming ability make it useful as a bioindicator of the passability of streams and rivers. We wanted to investigate the potential of using eDNA to monitor the dispersal of the species in a remediated stream on a fine spatial and temporal scale.

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Ecology of the GoT Dragons

Image Credit: Game of Thrones, 2019

Adam and Sam talk macroecology and that’s pretty much it. How small would these dragons be? It’s very anti-climactic. We’ll do a supplemental later. Also SPOILERS. Though as we were a week behind, there’s some stuff that is currently incorrect re: the current status of the GoT dragons. Spoilers.

04:02 – Everyone’s Favourite Dragons
13:15 – The Ecology of the Dragons
40:13 – Balerion the Big Boi vs. The US Military

And as usual, you can check out last week’s podcast on the physiology of these flappy flaps flaps below.

Simulating the Evolution of Life in South America

Image Credit: johnno49, Pixabay licence, Image Cropped

Modeling the ecology and evolution of biodiversity: Biogeographical cradles, museums, and graves (2018) Rangel et al., Science, 244, DOI: 10.1126/science.aar5452

The Crux

Understanding the processes which drive biodiversity worldwide is never more crucial than now, in a world where biodiversity is shrinking rapidly. Biogeography, the study of species distributions, has come a long way, but there are still a lot of problems that need solving, including improving our understanding of the interactions between factors like climate change, dispersal abilities, fragmentation and species competition, to name a few.

This paper attempted to analyse some of the effects of those factors in concert, by producing a simulation of the evolutionary process in the world’s most biologically diverse continent, South America.

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Are Animals Doing the Wrong Thing?

The great tit (Parus major) needs to gain more than 10 % of its body weight in pure fat every evening, in order to survive a cold winter night (Image Credit: Frank Vassen, CC BY 2.0, Image Cropped)

Short-term insurance versus long-term bet-hedging strategies as adaptations to variable environments (2019). Haaland, T.R. et al., Evolution, 73, 145-157.

The Crux

Why do animals behave the way they do? Behavioral ecology is a field of research trying to explain the ecological rationale of animal decision making. But quite often, it turns out the animals are doing the ‘wrong’ thing. Why don’t all animals make the same choice, when there clearly is a best option? Why do animals consistently do too little or too much of something?

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Restoring Biodiversity Through Species Interactions

When species like this toucanet are lost, the interactions that they are a part of are lost too. So how can we restore them? (Image Credit: Jairmoreirafotografia, CC BY-SA 4.0, Image Cropped)

Estimating interaction credit for trophic rewilding in tropical forests (2018) Marjakangas, E.-L. et al., Philosophical Transactions of the Royal Society of Biology, 373, https://dx.doi/10.1098/rstb.2017.0435

The Crux

We have reviewed more than enough papers on biodiversity loss to entitle us to skip the whole “losing species is bad” spiel (see here, here and here). But what we haven’t talked about is that when some species are lost, specific interactions that those species participate in disappear from an ecosystem. Those interactions range from the minute to the crucial. One such crucial example is that of seed dispersal, whereby specific plants rely on specific animals to disperse their seeds, thus maximising biodiversity in other parts of the forest and creating a positive feedback loop.

Naturally, conservationists will want to reintroduce animals to propagate some of these reactions. But as is always the case in conservation, maximising return is absolutely essential when you’re faced with limited resources and a lot of ground to cover. Today’s authors wanted to develop a system for maximising the effect of species reintroduction.

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The Effects of City Life On a Species’ Body

Species like the anole exist in natural and urban environments. So how does where they live affect their body shape? (Image Credit: RobinSings, CC BY-SA 4.0, Image Cropped)

Linking locomotor performance to morphological shifts in urban lizards (2018) Winchell, K. et al., Proceedings of the Royal Society of Biological Sciences, 285, http://dx.doi.org/10.1098/rspb.2018.0229

The Crux

We know that human construction leads to displacement of many species, regardless of the ecosystem. But just because we put up a city, doesn’t mean that all the species that lived there go disappear. Some stay and adapt to their new surroundings. Understanding how certain types of organism respond to new environments is important when considering our impact on a species.

Today’s paper looks at the response of lizards, in this case anoles, to living in the city. The authors wanted to find out, among other things, whether individuals of the selected species showed different locomotive abilities on natural and man-made surfaces based on whether or not they came from the city or the forest, and whether these corresponded to morphological differences.

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Shannon McCauley: The Rise of Community Ecology

"...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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Snakes Spreading Seeds

The sidewinder rattlesnake, one of many snakes that inadvertently transports seeds by swallowing small herbivores

The sidewinder rattlesnake, one of many snakes that inadvertently transports seeds by swallowing small herbivores (Image Credit: Brian Gratwicke, CC BY 2.0, Image Cropped)

Seed ingestion and germination in rattlesnakes: overlooked agents of rescue and secondary dispersal (2018) Reiserer et al., Proceedings of the Royal Society B: Biological Sciences, DOI:10.1098/rspb.2017.2755

The Crux

Plants depend on outside forces to disperse their seeds away from the parent plant, and the most common way is via a process called zoochory, where animals spread the seeds. This can be due to seeds being stuck onto the fur of an animal, animals taking and storing the seeds in a different location, or when an animal eats the fruit and later defecates the seeds.

One indirect way in which seeds are dispersed is when a predator, such as a coyote, raptor, or bobcat, consumes an animal (like a mouse) that had seeds in its stomach or cheek pouches. Rattlesnakes commonly consume small rodents that carry seeds in cheek pouches, and though these snakes are known to eat these seed-carrying animals, their own role in seed dispersal remains largely unknown. In order to learn more, the researchers in this study dissected museum specimens to search for secondarily-consumed seeds.

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