What the Hell is Biodiversity?
Slippery dicks, donkey dungs, yellow assessors, bloody bigeyes, bilbies, cuscuses, bandicoots and potoroos.* Scientists describe an ecosystem as biodiverse (i.e. it has biodiversity) if it includes lots of different types of animals and plants-the greater the variation, the greater the biodiversity. Simple enough, but that’s not really a satisfying answer, is it?
*(FYI: those first four critters are coral reef creatures and the last four are marsupials.)
To get to the bottom of this biodiversity business, we need to take a short trip down evolutionary lane. (This’ll be quick, I promise.) Life is one big competition, at least according to Darwin’s whole “survival of the fittest” theory. Every living organism-from the biggest blue whale down to the smallest virus-is constantly trying to win. Win what? Win the chance to pass their genes on to future generations-these winners get babies. Not an all-expenses paid vacation or million-dollar prize, just babies.
But to level the field in the great baby-making game of life, we need biodiversity. And to understand what baby making has to do with biodiversity, you need to understand that life is not like a box of chocolates. Life is like a game of dodgeball.
Imagine a dodgeball game with only one player on each side. (That would be a pretty crappy dodgeball game.) If one player has an obvious advantage (like a massive throwing arm and a “Dodgeball = Life” tattoo), he’ll probably win no matter how many times the two play each other. But if you add ten extra players to each side, it gets harder to predict which team will win-even with the über-player in the game. Now, give everyone a ball, get rid of the rules and the teams and yell “Every man for himself!” and who the hell knows who will come out on top.
The one-on-one game is an example of low biodiversity while the free-for-all game has the highest biodiversity. And with more players in the game and balls flying every which way, our big-armed, tattooed brute is more likely to get knocked on his ass than dominate the game.
As an ecosystem becomes less biodiverse (which happens as plants and animals go extinct), the amount of competition drops and that makes it easier for certain species (like the dodgeball-loving brute) to dominate. For example, the recent worldwide surge in jellyfish is due partly to increases in pollution and higher ocean temperatures, but biodiversity loss is the real culprit. By removing lots of big fish (top predators like tuna, sharks and swordfish), we’ve reduced the biodiversity of the ocean. And it just so happens that the fish we like to eat are some of the fish that like to eat jellies. Without predators to gobble them up, the jellies are going wild, floating into protected coves, getting entangled in fishermen’s nets and stinging unsuspecting skinny dippers.
Just as Darwin explained, the jellies are winning, and they are the ones getting to make more babies. And the more they sting skinny-dippers, the fewer babies those skinny-dippers will be making. And that, my friends, is the story of biodiversity.