Here's another story in our series on citizen science in California, our way of celebrating Citizen Science Day on April 16.
By now the story has become something of a local legend. It goes something like this: Brian Brown, entomology curator at the Natural History Museum in Los Angeles, bet a museum donor that he could find a new species, entirely unknown to science, just about anywhere.
It sounds like an audacious claim until you realize that there are perhaps as many as 8.7 billion species that exist, right now, on planet Earth. Of those, most are animals. Then there are more than a quarter million plant species, and nearly two thirds of a million kinds of fungi. The rest are critters like protozoans and algae. We are members of a staggeringly large biological family tree, exceedingly difficult to comprehend in its vastness.
Think of every animal you know about. All the bumblebees and dragonflies, every type of fox and antelope, lizard and pigeon, bluebird and mountain lion, coyote and koala. Then add all the zebras and giraffes and lions and crocodiles, plus each type of whale and sea lion, all the shrimps and clams, sea stars and lake bass, frogs and jellyfish. There are flowers and trees and ferns and kelp, tiny parasitic plants that live only inside other plants, and even tinier organisms that feed only on those parasitic plants.
After you account for every single species we know about, you're left with just 1.2 million. According to one estimate, some 86 percent of terrestrial species remain entirely unknown, plus another 91 percent of marine critters. Given all that, it seems as if Brown would actually have to try hard not to discover a new species every time he turned over another rock or fallen tree branch.
The museum donor accepted Brown's bet, so he set up a malaise trap in her Brentwood backyard. The malaise trap, named by its inventor, Swedish entomologist Rene Malaise, is quite simple. It looks something like a tent. Insects fly in and get funneled towards the top. Unable to escape, they fall into a jar filled with alcohol where they stay fresh (slightly pickled, perhaps) until a researcher retrieves them and inspects his or her entomological bounty.
All sorts of critters wind up in a malaise trap: flies, bees, butterflies, moths, leafhoppers, and even spiders. But Brown is an expert on a certain family of flies called phorids, so he focused only on those, ignoring all the rest. The very first one he inspected turned out to be a previously undescribed species, entirely new to the scientific establishment. (The second and third phorids he examined, by the way, were the first North American records of those species, one of which hailed from Europe and one from Africa.)
He'd won the bet, but the discovery sparked a grander idea. What if he could deploy an array of malaise traps, all over the city? He could use the bugs that collect inside of those jars as a means of understanding the relationship between biodiversity and urbanization.
Los Angeles is something of an odd city. It's one of just two megacities in the world, cities with more than 10 million people, that are also home to large cats. (Mumbai has leopards; we have mountain lions.) Manicured lawns and glass-covered skyscrapers are in some places a stone's throw away from undeveloped chaparral. We sit in one of the world's few biodiversity hotspots, an honorific given to areas with lots of native species found there and nowhere else on the planet (also known as endemic) but with serious habitat loss. The "California Floristic Province," as it is called, is biologically diverse but under extreme threat.
We have a decent idea of how urbanization impacts the most charismatic of our non-human neighbors. Highways can create metaphorical islands in the middle of the city, green patches surrounded by a sea of cement, like Griffith Park. Bobcats living on opposite sides of the 101 remain genetically isolated and risk inbreeding because of it. Just about every dead mammal that gets a necropsy shows evidence of rat poison in its system. Over the last 100 years, Griffith Park lost ten of its butterfly species. But what about the overlooked critters, the phorid flies of the world?
Brown and his colleagues unleashed thirty malaise traps unto the city. Twenty-seven of them were the backyards of citizen scientists, plus another in the museum's nature garden, one in a community garden, and a third at an elementary school. The project was called BioSCAN, which stands for "Biodiversity Science: City And Nature."
In addition to discovering important scientific information about the link between biodiversity and urban development, Brown, along with Emily Hartop and Lisa Gonzalez, would go on to discover and describe 30 species of phorid flies entirely new to science. They're in the process of publishing information on yet another dozen new species. (The best way to identify a new phorid species? Look at its genitals under a microscope, an anatomical detail about which Hartop has perhaps become one of the world's leading experts.)
And now the project has expanded. During the first phase of BioSCAN, the researchers focused on a small swath of land from the urban core near downtown north to the mountains. Now, in phase II, the researchers have enlisted the help of seventeen citizen scientist households on a transect from the Santa Monica coast all the way east to the deserts of San Bernardino County. BioSCAN Phase II is part of a broader museum effort known as the "Super+ Project." In addition to hosting a malaise trap in their yards, these heroic folks survey their yards twice each month for reptiles and amphibians, snails and slugs, squirrels and spiders.
"It's interesting that after going through all 43,000 phorid flies, we had 42 [new] species, and now within the first couple of samples from just this one site," Brown says, pointing at a map of the Super+ sites, "we already have six more new species." That site also happens to be Brown's own house, and it's located just a few miles from the cluster of Phase I homes. "It shows you that [biodiversity] can change quite a bit, even over a small distance."
It could be hypothesized that more biodiversity occurs closer to the mountains or the coast with less diversity in more densely populated, highly developed parts of the city. But it's not yet apparent just what might drive such a pattern, if it exists at all.
"We've tried to associate the biodiversity that we've found with some of the urbanization factors," like amount of hardscape nearby, distance from roads, proximity to a water source, and so on," explains Brown. "And there hasn't been any strong association that we've found yet."
But if there's one lesson that has been learned from BioSCAN thus far it's that there are lots of things that homeowners can do to make their own yards more biodiverse, like landscaping with a variety of species, especially native trees, or by providing a bit of moisture.
Then there are more creative methods for boosting your backyard biodiversity, which may be less advisable. "Why do you have so many coffin flies in your backyard," Brown recalls asking one BioSCAN host, who lives near the LA River. "It was a guy that buried his pets in his backyard."