EARTH’S LIVING ORGANISMS AND THEIR ROLES
Let’s begin by looking at the estimated number of living organisms on our planet and the important roles they perform to support the cycle of life and the sustainability of Earth’s ecosystems:
That’s more than 4 million species that have been described, not including bacteria. That may seem like a lot, but every species has a purpose in its ecosystems. Some species may perform the same role as others but in different environments or in different way.
Animals include birds, invertebrates, insects, mammals, reptiles, amphibians, and fish, which support other organisms in their ecosystem through seed dispersal, pollination, being a food source, regulating population sizes, decomposing organic matter, and recycling nutrients to name a few.
Plants & algae, called photosynthetic autotrophs (they create their own energy through photosynthesis), create consumable energy and oxygen, which supports the existence of every living animal as well as some bacteria and fungi species.
Fungi are like an ecosystem’s digestive tract; they decompose and recycle nutrients and organic matter into forms plants can utilize. They form an underground network that connects plants, transferring nutrients from one plant to another and storing carbon underground that plants pull from the atmosphere during photosynthesis.
Bacteria exist almost everywhere on the planet and fulfill a wide range of ecosystem roles in a multitude of ways. They can be producers in the depths of the ocean, where they use naturally occurring chemicals to create energy, or closer to the surface and on land, where they photosynthesize similarly to plants and algae. They decompose organic matter and continue the cycle of carbon and nutrients into forms that plants can use. They also fix nitrogen, which is a vital ingredient for energy production and storage in plants.
When it comes to ecosystems, the need for such diversity in species that perform a certain role is important. Some species may perform a role alongside others that collectively provide the full service to the ecosystem, while others perform the whole service but in different types of ecosystems or at different trophic levels. All parts must be supported to ensure ecosystem resilience and health.
Now that we understand that ecosystems need a diversity of species to keep them healthy, how does diversity develop? To ensure that we support the existence of biodiversity, we must learn how it evolves into existence. What are the driving forces behind biodiversity?
Ecologists have identified three driving forces behind biodiversity which occur at different levels, all of which support each other: