Welcome to the third lesson of our What Is Nature? series.

Biodiversity is the fabric of life! It is interwoven into every aspect of life. It is how and why life on Earth thrives. Without biodiversity, life as we know it would not be able to exist.

Let’s start with a quick overview of one of the Earth’s four vital subsystems, the biosphere. The biosphere is a global ecosystem made up of living organisms (biota) and the nonliving (abiotic) factors that provide them with energy and nutrients. Its components include the other four vital “spheres” or subsystems, the atmosphere (air), lithosphere (land), and hydrosphere (water).

Activities in the biosphere influence the chemical composition and natural processes of the atmosphere, lithosphere, and hydrosphere. Here’s a quick example: Plants take carbon dioxide from the atmosphere, nutrients from the lithosphere, and water from the hydrosphere as a part of photosynthesis so they can create their own energy source. Plants release oxygen back into the atmosphere, which supports all living creatures, and water vapor which helps form clouds that reflect solar radiation. This process also stores carbon in the soil as well as within the plants themselves. 

The biosphere provides the necessary environmental conditions for survival. Living organisms are required to adapt to the environment of the biosphere. The biosphere is home to biodiversity within ecosystems while providing reliable sources of food on Earth.

Greater biodiversity in ecosystems, species, and individuals leads to greater stability. For example, species with high genetic diversity and many populations that are adapted to a wide variety of conditions are more likely to be able to weather disturbances, disease, and climate change.

In this lesson, you will learn about:

  • Earth’s Living Organisms and Their Roles
  • Genetic Diversity
  • Species Diversity
  • Ecosystem Diversity
  • Biodiversity Hotspots


The word “biodiversity” is short for biological diversity; bio means life, and diversity means varietyIt is a way to describe the variety of living organisms and the diverse interactions they have with other organisms and their environment. These organisms are the many types of plants, fungi, algae, animals, and bacteria. The environment they are found in varies in scale. It can include ALL the organisms found on Earth or the organisms found, on a smaller scale, in a pond habitat or forest ecosystem. (We covered this in our first lesson How Nature Works). 

The biodiversity of ecosystems found on Earth today comes from more than 4.5 billion years of evolution, during which species have adapted their behavior to survive the presence of other species and environmental changes and, over time, physically evolved into new species. From the birth of the first single-celled organism, bacteria and land-based plants evolved and changed our atmosphere into an oxygen-rich ecosystem where insects, reptiles, birds, and mammals—including humans—evolved into existence.

Not only have living organisms adapted and evolved to the environments they live in, but they have adapted to the presence of other species that share their habitat. (See Lesson 2, Pollinators, about how pollinators and plants adapt and evolve in response to each other, making them more efficient pollinators and better at reproduction.)

Biodiversity is essential to life as we know it, but did you know that we are currently experiencing Earth’s sixth mass extinction event? The difference between this one and the other five, such as the one that caused the extinction of the dinosaurs, is that human activity is the core reason for the decline in species and their population sizes!

The International Union for Conservation of Nature (IUCN) Red List of Threatened Species tracks global species populations. Their report, An Assessment of Endangered Primates, dated June 21, 2021, reveals that almost 70% of all non-human primates across the globe are Critically Endangered, Endangered, Threatened, or Vulnerable to extinction. To understand more about these conservation statuses, visit The Alphabet Soup of Conservation.

Since human activity is causing this decline, we also have the power to prevent it. That is why, in this lesson, we are going to learn how biodiversity supports a healthy ecosystem and is essential in supporting human life. 

The natural world is changing. And we are totally dependent on that world. It provides our food, water, and air. It is the most precious thing we have and we need to defend it.

Copyright © New England Primate Conservancy 2023. You may freely use, copy and share these Learning Activities for educational purposes. 
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