Snakes Might Play a Role as Ecosystem Engineers
In a balanced ecosystem, every organism has a particular role and in general, snakes have played both the role of predator and prey. They have held a fairly comfortable place somewhere in the middle of the food chain with no real known interaction with the foundations of their ecosystem. This assumption has been shaken up by a study that was published in 2018 that presents evidence that snakes may fill the ecosystem engineer role in addition to the role of mid-level predator in the food chain.
Ecosystem engineers are organisms that have a major impact on their physical habitat, and consequently the ecosystem as a whole. The creatures may create, modify, maintain or destroy their habitat and their presence is often followed by the creation of a diverse community. A common example of an ecosystem engineer is the beaver because they build their dams that block the flow of a waterway and the result is a pond that provides a brand new habitat for a number of other species from waterfowl to bears. Of course, the researchers are not suggesting that snakes affecting their own habitats as dramatically as beavers, but they may play a role in seed dispersal.
The scientists that published the study (Randall S. Reiserer, Gordon W. Schuett, and Harry W. Greene) looked at the contents of the digestive tracts of 50 preserved rattlesnakes available in the Museum of Vertebrate Zoology, University of California at Berkeley. These specimens had been originally wild-collected in the deserts of Arizona and California then preserved and stored for use in research. In 45 of the 50 specimens, the researchers found the remains of rodents and a total of 971 relatively undamaged seeds. The seeds that we specifically found in large intestines showed signs that they had begun to germinate, or had begun to grow. But how did those seeds get in the snakes’ digestive tracts if they are obligate carnivores and only eat meat?
The answer to the question of where the seeds come from can be found with the rodents that make up the bulk of their diet. Rodents tend to feed on seeds and have specialized cheek pouches that allow them to store more seeds to be transported to a safe location. Sometimes a rodent with seeds in those handy dandy cheek pouches becomes dinner to a hungry snake because snakes swallow their prey whole and lack the capability of breaking down plant matter, the seeds end up relatively unharmed as they pass through the digestive tract. Since the seeds pass through the digestive system relatively unharmed, they have the opportunity to grow into a brand new plant possibly far from where they were originally harvested by the original rodent. This roundabout process allows plant species to spread into new corners of the habitat.
While interpreting the information gained through the study, the researchers found evidence that it may even be beneficial for seeds to end up inside the digestive system of a snake. The specific evidence is in the form of germinating seeds mentioned earlier. The snakes in the study are specifically from the desert ecosystem where many plants produce chemicals that stop their seeds from geminating until certain conditions are met, like enough rainfall to leech away the chemicals or exposure to fire. The study suggests that the time spent in the snake digestive system allows for the leeching away of those chemicals and the germination of the seeds, which could possibly take years under different circumstances.
I am fascinated by the implications of this study that snakes play a more major role in the ecosystem, however, it appears that more research into the subject has yet to be conducted. While accelerating the germination of seeds is beneficial to an ecosystem and helps to maintain the flora in the habitat, I am doubtful that snakes should really be labeled ecosystem engineers. I think that more research needs to be done before the label is applied so that scientific language remains clear and well defined. I genuinely hope that this line of study is continued and I look forward to reading future studies that explore the secret lives of snakes.
References:
https://news.cornell.edu/stories/2018/02/snakes-act-ecosystem-engineers-seed-dispersal
https://royalsocietypublishing.org/doi/full/10.1098/rspb.2017.2755
