One of the challenges of ecology is that its data take time to exist. If you want to study the offspring of some yeast cells you poked somehow, just take a long lunch break and they’ll be waiting for you in about 80 minutes. Go away for a full day and you’ll come back to the 18th generation of baby yeast cells. (That’s not to say yeast studies are easy, their time investments just come in different forms.) If you want to look over the same number of generations of a larger, longer-lived mammal, you need a longer data history.
So imagine if you had 55 years of data about wolves and moose on a small island. And now imagine if the wolf population was in trouble–small and inbred. Would you sit by and let the wolves die out, or would you try to throw them a life vest? And in either case, how does the value of your data change?
Those are some of the questions being asked on Isle Royale, a small island 15 miles into Lake Superior. But they’re also being asked of you.
In the 1960s, a guy named Bob Paine picked a small stretch of rocky beach in Washington state and evicted its sea stars, crowbarring them off the rocks and throwing them back into the ocean. Within a year, the beach’s demographics had changed dramatically: barnacles and then mussels replaced algae and limpets. Species richness, or the number of different species present, hadn’t gone down by the number of sea stars–it had halved.
Paine realized the reason behind the shift was that without the sea stars around to eat barnacles and mussels, their populations skyrocketed, and their demand for algae and limpets increased, causing those populations to crash. He called the three-step chain a “trophic cascade”; the sea stars at the top that shaped the chain he called an “apex predator.”
I’m fascinated by the relationships between species, particularly when you bring evolution into the picture. So I was pleased to meet a collection of birds like this charmer living along the southern coast of Brazil, courtesy of a recent Science article and its resulting coverage, and I wanted to share the acquaintance with all of you.
But first, let’s take a step back, this being lunch time, to…fruit!