Genuine question. I was talking to someone recently and they asked me this and while I had some answers (mentioned below), I didn’t have confidence in my answers.
I know climate change is a threat to biodiversity and that it’s important to preserve it but I was never told why biodiversity is important. Is it to keep ecosystems in check (I feel like this is probably one of the most important reasons)? Is it to just give humans a bunch of species to look at and appreciate? Is it to ensure that if the human population died, some forms of life would remain that would be fit for whatever catastrophe affected human populations and keep life going?
Is it all of these things? Any other reasons?
Thank you!
In: Biology
Well, let’s roll it back a bit and think of just people. We’re all different. I’m more of a maths and science sort of person. People like me can study things and invent stuff that makes life easier or even possible. On the other hand, my wife is much more the artistic and emotional type. People like her make things which make life worthwhile, or help us deal with difficult situations. Humanity thrives with different types of people work together.
In a similar way, nature thrives when different species of plants and animals “work together,” each fulfilling different roles.
One of the often mentioned ones is the fragility of a monoculture ([the opposite of biodiversity](https://en.wikipedia.org/wiki/Monoculture), at least as far as farming goes). Problems include diseases spreading faster (biodiversity means microbes need to be biodiverse as well). The availability of food is also impacted; with plants, it means certain nutrients that are used in some plants but not others will be drained/built up faster than they can be replenished/drained with the soil.
Think of it this way:
If there were only humans and human’s solely survived on eating apples, everything is great, we farm enough apples to feed everyone and it’s good. There’s no other plants, we don’t need them, we have apples.
Suddenly, there’s a new disease or weather condition that wipes out all the apples. Now humans have nothing to eat and they all starve. If only there were some other plants around humans could have eaten instead.
Our food chain relies a lot on nature and other animals. Insects polinate a lot of our food, which we need for example. Large amounts of biodiversity helps keep all the existing eco systems and food chains in balance. The more diverse, the less impact one part of it being harmed has.
Going back to my original example. Instead of just eating apples, humans now survive on all kinds of foods, as we actually do. Now, a disease wipes out all the apples, people miss apples but humans survive because we have other food sources.
What appear to be inconsequential changes to environments almost always have huge unforeseen implications later down the line.
Preserving how things are prevent these disasters.
As a real example, overfishing of an area leads to a reduction in the large predatory fish. This theoretically would sort itself out in a matter of months, however:
In actuality this leads to a surge in smaller fish who eat plant life/plankton type species. This then causes a shortage of available food for the even smaller creatures who then have their numbers vastly reduced.
This then weirdly causes a huge surge in algae on the surface of the water as it is suddenly able to reproduce faster than it is being eaten.
The algae grows so thick that it blocks light and reduces oxygen levels in the water eventually causing an extinction event killing all aquatic life in the area. This will also affect land creatures and can continue causing issues elsewhere. This is called a Fish Kill and happens often enough that it has a name. The initial causes vary but something knocks the biodiversity out of balance and causes a cascading chain of events.
Disclaimer: this is one potential scenario and is not the case every time.
My answer for five year olds: every lifeform is like a thread in a fabric, the fabric being a forest, lake, meadow or the like. With species drastically declining in numbers or disappearing altogether, the fabric thins out and even gets wholes. At some point it can no longer function and falls apart completely.
Diversity brings strength. In plants, having a “monocrop” is extremely dangerous. Example #1 of this is the Irish potato famine. GMOs are bad because they lead to monocrops and while they aren’t susceptible to disease, heirloom varieties have different minerals and nutrients- they also support other animal/insect species. A keystone species is one where if they disappear, many many others follow. Think of it like bolts on a plane- if they keep falling off eventually the plane will crash. Diversity in animals is important because genetically we need variety to be strong. Think of dogs. Pure breeds suffer from many diseases and have weird personalities a lot of time due to inbreeding– the mut you get at the pound is likely to live long and have good genes.
Think about bio diversity in food terms.
You need to eat a balanced diet, right. Fruits, vegetables, protein, carbs, etc.
Well, what if for example we were to lose alllll biodiversity and the only food left in the world was lettuce, a lot of it, but just lettuce… humans wouldn’t be able to nourish themselves with just lettuce because we need all the vitamins, minerals, fibers, proteins, carbs, etc to survive. We would then die off and cease to exist.
Biodiversity like this happens on all different levels of life forms from plants to animals to bacteria and humans, etc. but as each level crumbles, it affects all those around it that rely on that as well and so on.
An example is how many cities in the US, when they were expanding in the 19th and 20th centuries, planted a huge number of American Elm trees because they liked the way they created tree lined streets. These trees were often the only tree planted in neighborhoods.
When the elm bark beetle came along and started spreading Dutch elm disease, many cities lost a large percentage of their tree canopy because the disease spread so easily. This leads to higher temperatures, increased cooling costs and a host of other health problems.
The lack of biodiversity among the trees planted made the problem worse than it needed to be.
These days new cities or neighborhoods with forward thinking planners will plant a good variety of trees to limit the impact of any one disease.
Look at bananas for example. Because of a loss of biodiversity in bananas, a single fungus is now threatening to their extinction. If there were multiple strains of bananas which weren’t t susceptible to the fungus still around, biodiversity, banana extinction wouldn’t be a serious concern.
>Is it to ensure that if the human population died, some forms of life would remain that would be fit for whatever catastrophe affected human populations and keep life going?
Everybody else has provided good answers on the main point so I will just expand a little on this: it would be virtually impossible to wipe out life on Earth.
We could set off every nuke ever made and we’d certainly wipe out a massive number of species but life would carry on. Radiation would pose a risk for decades, not to mention the effects on climate that would likely linger beyond this, but these effects would be extremely brief on a geological time scale and life would just start evolving again from whatever survived in the deepest nooks and crannies of the planets surface, oceans and even in the Earth’s crust.
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