Environmental Plots: Extinction

On to another one of my environmental plots.
This one ties in to a lot of other posts - some i've written, and some I haven't.

Extinction.
When a species disappears completely.
There is also Extirpation, where a species disappears from one area, but still exists somewhere else.
And a species can be extinct in the wild, but still exist in captivity.
There are a couple other levels too. There may be so few of a species left that they can no longer fulfill their biological role, as predators or scavengers or whatever they happen to do.
Or there may be so few animals left that there is no way their population could ever recover. Or even if they do begin to pick up their nnumbers, their gene pool may be so small that it puts the entire populaton at rsk of disease or disaster.

There are a number of things that can contrbute to the extinction of a species.
Habitat destruction. When we cut down or build over their homeland, the animals/plants no longer have anywhere to live or look for food. This is one of the biggest causes of extinction.
Overharvesting. When we hunt and kill/capture too many of a species, we can drive them to extinction. An excellent example is the passenger pigeon. Long ago, there were so many of these birds that flocks of them would darken the sky from horizon to horizon. But people were so intent on hunting them that there are none left.
Invasive species. When species are brought from a distant land, they may not have any predators in their new home (I'll have a whole post abotu invasive species). Some invasive species are able to out-compete more fragile native species. They'll eat all the food, or eat the species themselves. The California red-legged from is one such species that is put at risk from a tough outsider (a bull frog).
Pollution. Chemicals and air pollution can put species at risk. For example, when a highway runs near sensitive grasslands, like the serpentine grasslands in California, the exhaust from the cars can actually change the composition of the soil and make it harder for the native plants to grow in the rare soil type that they evolved to use. Also, trash can choke animals that eat it (sea turttles swallowing plastic bags, thinking that they're jellyfish). And toxins can kill animals too.
Climate change is a newer threat. Climate change causes the ice caps to melt earlier and freeze later. Which is very bad for animals like polar bears, who need the ice to hunt for food. But climate change can also warm certain areas, and allow diseases and fungi to spread to places that they haven't been before. This is very dangerous to amphibians, who are vulnerable to hese sorts of things because they can absorb bad stuff through their skin.

What can extinction cause?
Well, first of all, we are causing an entire species to disappear, which is terrible and beyond anything our species has the right to do.
But also, what if those speciees could be useful to us? There are many plants in the rainforests that have gone extinct before we even knew they existed. What if some of those plants had important medicinal qualities that could have helped with terrible diseases?
But even more important has to do with the niche that the species fills: their role in the environment. Every creature does something to keep the ecosystem in balance. And some species are incredibly important to their ecosystem. These important creatures are called keystone species. For example, the sea otter. Otters eat sea urchins. But when too many otters were hunted for their fur, the sea urchins didn't have that predator to keep their numbers in check. So the sea urchins ate the bases of the kelp that made up the kelp forests. Big hunks of the kelpforest dimply drifted away, making large areas of that habitat completely disappear. All because one species started to go into decline.
When wolves were hunted out of North America, that top predator was no longer there to keep deer and so many other animals in check. And because of the larger numbers of prey animals, many areas actually changed drastically because of the many deer eating more foliage, and more beacvers building more dams and flooding more land.
When a species disappears, is can potentially have disastrous effects on the areas it used to live in. And that is not a risk worth taking.
In the words of John Muir, "When we try to pick out anything by itself, we find it hitched to everything else in the Universe."
Everything is connected. The more you unbalance the delicate system of the planet, the worse things could end up.

It's not always the big impressive animals that are important. Remember, tiny fish, bugs, and ever flowers also need to be preserved.
Even so, hundreds of species are going extinct today. Humans are now the cause of a massive extinction - and there have only been a handful of those in the history of the planet. For example, the comet that wiped out the dinosaurs.
We are now causing as much damage as that.

Who else has used this idea?
A manga called Cat Paradise. In this series, the gods of extinct animals came back to try to take revenge on the humans that caused their speciesto disappear.
Jurassic Park looked at what might happen if a species that had been extinct for many ages appeared into a new, different world.
In Star Trek 4: The Voyage Home, humpback whales are extinct in the future. But humpback whales had friends on a distant planet. And when the whales stopped communicating, these aliens came to investigate, nearly destroying Earth in the process. Captain Kirk and his crew have to go back in time to bring a pair of humpback whales to the future, to save the planet and save the species.
In the anime Wolf's Rain, many speces have gone extinct, such as the elephant. Most people think that wolves are extinct too. But wolves have learned to disguise themselves as humans, in order to survive.
In the book Oryx and Crake, the members of a secret organiation all had code names of animals that were extinct.

How can you use this idea in a story?
Maybe an important species goes extinct. It could send an area into chaos. Or perhaps the people living there had a very important use for that species. What are they going to do now that it's gone? Did the species provide wool? Or was it a medicinal plant?
Or what if a species that is starting to go extinct starts to fight back?
What if humans were in danger of going extinct?