Tag Archives: dispersal

Simulating the Evolution of Life in South America

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: Ian Frank, CC BY 2.0)

Guest post by Thomas Haaland

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)

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)

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)

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)

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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Between a Dam and a Hard Place

Dams like this change the flow regimes of rivers, and prevent some species from accessing their spawning grounds, lowering population viability. But is removing them completely danger-free? (

Dams like this change the flow regimes of rivers, and prevent some species from accessing their spawning grounds, lowering population viability. But is removing them completely danger-free? (Image Credit: pxhere, CC0)

Anybody who has ever studied freshwater ecosystems will end up having to study dams at some point. And they’ll no doubt learn that dams are the enemy. They fragment ecosystems. They cut fish off from their spawning grounds. They change flow regimes. So it makes sense that the recent trend of dam removal across Europe and the world in general would please ecologists. But there’s a problem with dam removal, and it comes in the form of invasive species.

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