It is important that young people realize that cooperative / mutualistic relationships abound in the worlds around – and within – us. So much emphasis tends to be placed upon the competitive, sometimes brutal interactions that are sometimes found in food chains. Yet, just as vital are the symbiotic, coevolved relationships. Fine examples of this include the partnerships that exist between most Northeastern forest trees and various kinds of mycorrhizal fungi. The various fungi ferry minerals (and other materials) into the trees’ root. sIn exchange, the plants supply the fungi with sugars they’ve formed during photosynthesis. Similarly, we could cite the mutually beneficial relationships that are at play between leguminous plants and the bacteria who live within their roots (in sheltering, coevolved nodules). In this case, the bacteria receive food and protection as they transform nitrogen compounds into a form that the plants can actually absorb and use. Other examples of mutually beneficial relationships would be those between the many types of bacteria who inhabit the digestive systems of most animals. These little single celled beings provide all sorts of services (including in some cases, the provision of vitamins) in exchange for the protection and food that they find within the animals’ guts. Pollination partnerships between flowering plants and a wide range of pollinators are both amazing and often obvious. They are typically the products of millions of years of intricate coevolution. Dispersal partnerships between animals and plants are also wonderfully ingenious and result in the production of all sort of delicious and beautiful fruits. A more indirect but still essential type of cooperation exists between various creatures whose prey species are also busy eating other creatures. This is difficult to describe abstractly but easy to understand if we just focus on particular situations. For instance, a Chickadee foraging for insect eggs and insect larvae on a blooming Shadbush is an essential helper to that plant. Without the Chickadee’s work limiting the number of insect predators, the plant’s ability to grow and produce fruit would be somewhat diminished. Similarly, the Bobcat who catches White Footed Mice in the forest helps protect tree saplings from the ravages of these small but mighty herbivores.. This type of mutually beneficial interaction between two different species separated by at least one level of the food web is summarized by the useful phrase “trophic cascade.” All of these mutualistic relationships are ubiquitous and essential to the functioning of biomes – not only in the Northeast Forestlands, but globally.
Here is a simple, introductory worksheet that reinforces students’ awareness of some of these partnerships. Encourage them to color the various creatures (time permitting) after they’ve drawn lines connecting those animals and plants who have partnerships. Older students can just write the name or number of the animal whose life activities benefit a particular plant – i.e., who has a relationship with the plant that enhances the survival of both parties in the ‘team.’
Following an actual field trip, readings, or discussions, this page can be completed as an individual or class project. Such a process, we hope, will enable young people to better appreciate the networks of reciprocity, as well as those of competition, that sustain healthy ecosystems.
Here is the PDF: Plant and Animal Partnerships EB