Wednesday, June 17, 2015

Would dinosaurs be invasive?

In the first Jurassic Park movie, long-extinct dinosaurs and plants were brought back to life and were "contained" in a zoo/park for amusement of tourists.  As with most species intentionally introduced by scientists, there were several worst-case scenario contingency plans... which all failed.  In fact, in all of the movies, someone has a plan to move the dinosaurs off of the island for one reason or another and no one seems to take into account that they may escape and become invasive species.

Species which are introduced into a new ecosystem have the potential to become invasive. Some of the qualities that define an invasive species are:
  • non-native to the ecosystem in question
  • no enemies or pests to keep the population in check
  • successfully reproducing and surviving in new habitat
  • competes with native species for food, space, water, etc.
  • causes ecological, economical, or human health harm

Accidental introduction of larger animals into a new area is a little more rare and a population may have difficulty establishing.  They have to have a large enough starting population, are repeatedly introduced, or are naturally able to withstand any negative effects of inbreeding depression.  In the case of the dinosaurs seen in the movies, the likelihood of someone accidentally transporting a number of eggs, juveniles, or adults would be limited to the shipping containers and boats.  This kind of transmission of invasive animals is already an issue with the brown tree snake on Guam and some of the surrounding islands.  Every shipment is inspected to ensure that snake-free islands aren't accidentally infested when receiving goods from an infested island.  

brown tree snake (Boiga irregularis) by Gordon Rodda, U.S. Geological Survey,

In the original Jurassic Park, only one plant is mentioned to being brought back from extinction, but I doubt that it is the only one.  Scientists can tell from fossilized teeth what a particular dinosaur generally ate; carnivores have sharp serrated teeth for piercing and tearing flesh, herbivores have blunt teeth for stripping and grinding plants material, and omnivores have a mixture of teeth for tearing/piercing and grinding.  They can also evaluate fossilized digestive organs and coprolites for bones, plant pollen, and any other material that they may have eaten which survived digestion or were preserved before digestion could happen.  While some of the plant eating dinosaurs could potentially survive on living relatives of the plants that were around when they were still walking the Earth, they must have had to bring back some plants which are necessary to survival or to thrive. A dinosaur that is sickly because it is missing vital nutrients would likely draw activists rather than a paying crowd.  

Unlike the Jurassic Park franchise, moving invasive plants around is not limited to greedy employees, naive businessmen, misguided colleagues, or exploitative military officers.  Not only would there be the chance of employees intentionally or accidentally spreading plant propagules (seeds, roots, rhizomes, spores [ferns], etc.) off of the island, but anyone with a home garden may be tempted to snap off a plant tip to try to root it at home.  Problems already exist with potentially invasive plants moving all over the world, intentionally and accidentally.  There is much that we don't know about long-extinct plants, not only if they are a human/animal health concern, but also how they interact with the ecosystem that they were a part of and the ecosystems that they may be able to invade.  The U.S. and Europe already have to contend with giant hogweed, a nasty invasive plant from central Asia.

giant hogweed (Heracleum mantegazzianum) by Terry English, USDA APHIS PPQ,

giant hogweed (Heracleum mantegazzianum) by Thomas B. Denholm, New Jersey Department of Agriculture,

giant hogweed (Heracleum mantegazzianum) by Thomas B. Denholm, New Jersey Department of Agriculture,
Notice anything interesting about all of those images?  Everyone is wearing gloves to handle the plants.  The sap in the plant is phototoxic, meaning that if you come in contact with the sap and that area is exposed to light, you can suffer burns and blisters.  Other plants have allelopathic properties which inhibits other plant species from growing around them.  So, future extinct-plant-resurrecting scientists, for the sake of our ecosystems, keep it in the lab/greenhouse and away from the curious eyes of gardeners for now.