Going, Gone: NSF-Backed Research Probes Role of Luck in Extinction

 

Global forces, such as habitat loss, pollution or disease, often play the villain in extinction, implacably wiping species from the earth.

But in some cases, extinction could be due to plain bad luck. The vanished animal or plant might have simply built its home in the wrong place at the wrong time–the path of a typhoon or the site of the next Amazon warehouse.

Davidson College Biology Professor Kevin G. Smith and his research students aim to find out more about just what role random chance plays in extinction.

The National Science Foundation (NSF) has awarded Smith a prestigious Career Award of $770,000 to determine when happenstance is as big a factor in extinguishing a species as some of the more familiar explanations.

Current headlines indicate Smith and his team of Davidson research students need to hurry.

The Center for Biological Diversity estimates the normal rate of extinction at one to five species per year. Recent studies reveal that the Earth is losing plant and animal species at the rate of dozens per day.

"It wouldn't be ethical right now not to speak in this strong language to call attention to the severity of the problem," Gerardo Ceballos, a researcher at the Universidad Nacional Autónoma de México in Mexico City, recently told the New York Times about his study published this year, showing that mass extinctions may be closer than scientists have thought.

In addition to answering urgent scientific questions, Smith's NSF Career Award takes a long view as well: It specifically calls for the integration of research and education with the aim of developing tomorrow's scientists.

Smith's five-year project, "An undergraduate-intensive research program in experimental conservation biology," integrates all aspects of the scientific process for his students, from devising and running experiments through analyzing the data to publishing peer-reviewed results.

As a liberal arts college, Davidson adds even more value to the science itself. In fact, the liberal arts perspective is the main reason Smith left a successful research and administrative career track at a large university to come to Davidson in 2014.

"In some ways it takes a liberal arts perspective to study extinction," Smith said. "Why should we care that a species is disappearing from the earth? Not only does this idea of ‘humane instincts' in Davidson's statement of purpose help us understand the question better, but Davidson students will have the skills to do something about it."

For their experiments, Smith and company are building controlled ecosystems in grow-bag "forests" of goldenrod and in livestock-tank "lakes" of water in the Davidson College Ecological Preserve adjacent to campus and The Farm at Davidson.

Then they start killing.

They create miniature "extinction" (or local "extirpation") events and try to see what evolutionary bad luck looks like.

Smith has been studying the question since, early in his own studies of zoology, ecology and evolutionary biology, he read David M. Raup's Extinction: Bad Genes of Bad Luck?

Karen Lips, a biologist at the University of Maryland, has worked with Smith.

"Kevin's use of experimental approaches to understanding the randomness of extinction provides a controlled and statistically robust approach to studying extinction," she said. "Paleontologists have debated the relative influence of bad luck on extinction processes, and Kevin's real-time approach to studying this process on an ecological time scale is extremely relevant in our rapidly changing world."

Dodos, Spiders and Wolves

Despite disappearing 350 years ago, the dodo bird is among the best known extinct animals. It died off because it couldn't fly, or perhaps because Dutch sailors were hungry or maybe even because of a typhoon.

All of those factors may have played a role, but some are coincidental events and others are actual causes. Smith is trying to distinguish the two.

One influence on the Dodo's fate was that it lived only on the Indian Ocean island of Mauritius, a lush paradise about the size of Davidson College's home county of Mecklenburg.

Smith wondered, if he could travel back in time and establish 16th century Dodo bird colonies on the coasts of Africa, India and Australia, whether restaurants might be serving their eggs as a delicacy today.

He can't replicate a large-scale extinction, like the dodo, but by scaling down to a micro level, he can determine what rigorous scientific research is able to tell us about bad evolutionary "luck"–past, present and especially future.

In early June, green lynx spiders signaled the good health of the self-contained ecosystems that Smith and his research assistant Ryan Almeida '18 established last summer on several acres of meadow in the preserve–terrestrial ones flourish in 20 grow bags and aquatic ones in 20 cattle stock tanks.

"In the beginning, our philosophy was ‘If you build it, they will come,'" said Almeida.

Now the abundance of the green lynx spiders, a type of predatory arthropods, are like the proliferation of wolves at Yellowstone, Smith said.

"That the Yellowstone ecosystem is able to support wolves tells you that Yellowstone is doing pretty well," Smith said. "The green lynx makes me feel the same way about our little insect forests."

Almeida has already counted more than 60 insect species who have moved into these milkweed and goldenrod forests: Melanoplus grasshopper nymphs and Tramea carolina dragonflies, Monarch butterflies and jumping spiders, all the way down to tiny bugs barely visible to the naked eye.

Thirty yards up a slight rise toward the edge of the woods, the luck of the evolutionary draw is already visibly at work in two 65-gallon aquatic tanks.

The water in one is still and placid, its bright green algae flourishing in the late spring sun; the other is clearer, and teeming with tadpoles. Yet these widely divergent ecosystems started under identical conditions, side by side.

"Sometimes random chance matters," Smith said, peering at the tadpoles in one tank, then the algae in the other. "Tree frogs picked this habitat and they didn't pick that habitat."

The Hammer Drops

Smith's NSF Career Award funding will expand this terrain of possibilities, literally and figuratively.

First, Smith and Almeida will add more of each kind of the environments, enlarging some, planting some in the ground, adding more species to others. They will also add more students to the mix during the five-year run of the NSF grant.

"Biodiversity begets diversity," Smith said. "We're seeing biodiversity building on itself, which means that we're going to be able to ask more nuanced and interesting questions about extinction."

Then they will fell three-quarters of some of their mini-forests to study habitat loss. Or they might raise the temperature of some environments with heat-absorptive black tarps and water jugs to simulate climate change. They will implement controlled burns, introduce invasive species and otherwise mimic real-world events.

"Here, we can have a species that goes ‘extinct' over and over again," said Smith. "We can remove the effect of a really warm year or habitat loss, or the rarity of a species, or we can focus in on those effects."

"If we can't understand why certain species are going extinct, we can't predict future extinctions and prevent future extinctions, which ultimately is in our best interests," said Smith.

Almeida is hopeful that this vein of research will open up new possibilities to heal damaged ecosystems and prevent irreparable damage to the Earth.

"I'm an optimist," he said. "I can't deny the reality of global climate change and biodiversity loss, but I'm hopeful we're going to come together and really make some amazing strides in this field."

 

John Syme

josyme@davidson.edu

704-894-2130