Tag Archives: seed

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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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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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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