Welcome back to Nature League. This month, we're going to explore the concept of biodiversity, including why we do and should care about it.

[Intro]

Biodiversity is definitely a buzzword nowadays, and you've most likely come across it in the news or pop culture because we're losing so much of it on the species level. But, let's back up a second. I said "species level," because there are actually several accepted ways to think about biodiversity. The species level definition goes something like "the variety of species in an ecological community." But, species level biodiversity doesn't quite tell the whole story.

We can also think of biodiversity on the genetic level, which determines the evolutionary potential of all of those species. But, genes are tiny, right? And what about something bigger? Well, biodiversity can also be considered on the ecosystem level. So, a much more realistic view of the diversity of life on Earth is one that spans all the way from genes to ecosystems.

In addition to levels of biodiversity, we can also think about dimensions of biodiversity. Biologist use some odd terms for the three main dimensions, so let's break these down. The first dimension of biodiversity is the taxonomic, or classification, dimension of biodiversity. This is really just how many different species exist and where they are. But, this dimension doesn't really capture anything about these species; it's simply just how many there are.

What's more informative is the history of the species in an area, and how related they are. Like, it's one thing to say that there are 5 humans in a space, and another thing to say that there a 5 siblings in a space. One seems more diverse than the other. And, this is where the phylogenetic dimension comes in. Phylogenetics is a technical term for the history and relationships among species throughout time. So, the phylogenetic dimension of biodiversity is basically considering how unique something is evolutionarily, or how long a certain species has existed since diverging from a common ancestor.

Take my tuatara friend back here. This species is the only remaining member of an order of reptiles that lived during the age of dinosaurs, and all except the tuatara went extinct about 60 million years ago. So, this species represents a critical piece of phylogenetic biodiversity.

Functional biodiversity is exactly what it sound like- what are the ecological functions of the species in this area? This dimension is all about the jobs, or niches, of each species. So, if a certain region has species that do a ton of different ecological jobs and fill many, many ecological niches, we'd say the region is high in functional biodiversity.

I think the most interesting thing about biodiversity isn't its definition or level or dimension, but rather its value and use. Like, why do we, or should we, care about its existence? For the rest of this lesson plan, I'd like to explore three types of uses of biodiversity: direct use, indirect use, and non-use.

Direct use consists of provisioning services. Basically, organisms and their parts and products are used directly for human benefit; think food, building materials, paper products, medicine, etcetera. Indirect use consists of regulating and supporting services. These services are ones that don't directly use an organism, but rather use something the organism regulates or contributes to. Example include things like climate regulation, flood protection, and water filtration.

So, what about non-use? This one is my favorite. It turns out there are lots of ways we "use" biodiversity without actually using it at all. These kinds of services are cultural, aesthetic, and even spiritual. Non-use values of biodiversity are intrinsic or inherent. It's a philosophical concept, and can be described as something having value on its own, independent of its value to anyone or anything else. The concept is easier to understand with some examples. These non-use values include existence value, bequest value, and potential value. 

Let's look at existence value first. Existence value is the value of knowing something exists even if you never use it or see it. So, like, I personally value snow leopards being alive even though I don't eat them, or use them for clothing, or benefit from them affecting the climate, or interact with them. I just like knowing that they exist.

Bequest value is another example of a non-use value in biodiversity. This is the value of knowing something will exist for future generations; express something like "I value sharks being alive so that my grandchildren can enjoy them." 

And, then there's potential value, which is exactly what it sounds like. This is valuing biodiversity because it might come in handy to use in the future. When that time comes, the value changes from non-use to use; but, while it's hypothetical, it's technically non-use.

So, biodiversity has a lot of different uses, and the ways in which we personally rank the importance of those uses comes down to values. Some scientists argue that biodiversity might make ecosystems more stable and resilient, but this is incredibly hard to measure and quantify. Whatever your values are, there's something for everyone to love about the incredible diversity of life on Earth.

We've just scratched the surface of this complex but fascinating topic, and I challenge you to discover even more uses and values of biodiversity in your own life.

Thanks for watching this month's lesson plan here on Nature League. We'll see you next week for a field trip, where we'll explore biodiversity right here in an urban environment. 

[Outro]