The Good News About Lizards
Tiny lizards inspired biologist Thor Hanson to write a book: Hurricane Lizards and Plastic Squid: The Fraught and Fascinating Biology of Climate Change. I heard him speak in yet another fascinating Alan Alda Clear&Vivid podcast.
Hanson’s book, Alda says, is about “the ways plants and animals are responding as we humans are messing with their lives.”
“Hurricane Lizards”? The name speaks to the work of evolutionary biologist Colin Donihue and colleagues in the Turks and Caicos islands in the Caribbean.
As Hanson relates, Donihue and his team were studying and measuring lizards in 2017 when they had to leave the islands because of hurricanes Irma and Maria. They returned weeks later to see what impact the storms had had on the species (Anolis scriptus).
What did the survivors possess, they wondered, that enabled them to hang on while being belted by hurricane winds? The studies of this species that they’d done just prior to the hurricanes enabled them to compare characteristics of the survivors with those that had presumably been swept away.
Donihue’s team created an experiment with what was probably not a tried-and-true piece of scientific equipment: a commercial leaf blower.
I’ll eliminate the element of suspense and state at the outset that those scientists stressed no lizards were harmed during their research. (I’m not sure how they know that because it sounds like these little guys went for a harrowing ride.)
With a number of lizards clinging to a stick comparable to their natural environs, the researchers directed strong winds at them with the leaf blower.
As the researchers turned up the wind, the lizards raced to the other side of the stick. They held on with their sticky toe pads—larger toe pads than those on the lizards the team had measured before the hurricanes.
They also had longer front legs that helped them stay on the stick as the toe pads slipped, and shorter back legs that flapped like sails.
When they could no longer hold on, they dropped into a net the researchers had positioned below them. They were then released (presumably without therapy…).
These lizards had actually benefited from an evolutionary process enabling them to withstand unusually devastating winds. The researchers’ findings, they stated in Nature, provide nothing less than the first evidence of a species rapidly undergoing natural selection.
This is “directional selection,” Hanson says. Donihue and colleagues had “measured survival of the fittest in action.”
(If you’d like more information about these findings, Donihue has published an interesting article here. He noted that “the change in these traits was in the same direction for the lizard populations on both of the islands we sampled, suggesting that this remarkable pattern wasn’t just a fluke, hurricanes can consistently induce natural selection on populations in their path.”)
Hanson points out similar evidence of adaptability among trees, specifically oak trees. Large data sets from the US government have documented something that conjures up an extraordinary visual in my anthropomorphic imagination: trees move several kilometers each decade—even faster than some species of birds.
These movements are aided by birds: blue jays carry acorns long distances to areas where the climate is more hospitable. Then the little acorns start on their trajectory to become great oaks.
The Bad News About Lizards…And Time Mismatching
Discussing findings from the work of evolutionary biologist Barry Sinervo, Hanson speaks of desert lizards that spend part of their time during the long sunny days hiding under rocks to keep their body temperature stable.
But as the climate has warmed, the daily hours behind the rocks have increased. That means fewer hours to forage for food, which leads to less energy for reproduction. The result: some lizards aren’t breeding, a major disruption to the species.
We’re also now seeing “time mismatching” among species that depend upon each other, Hanson notes.
Flowers, reacting to the sun’s warmth, open at the time they’re ready for pollination. But the bees—“the most important pollinators”—living in the cooler ground–are on the “old schedule;” when they emerge, they miss that optimum time.
“The breakdowns of ecological relationships are one of the more subtle but critical aspects” of climate change, Hanson warns, and “will have tremendous consequences.”
The Potential for Human Survival
“Plasticity is the inherent genetic capacity to adapt,” Hanson says reassuringly. “Homo sapiens have a lot of it.”
With the benefit of technology, we have been expanding both our comfort and our ability to live in more and more places.
But, he says, our creature comforts, the technology we rely on, and our abundance of food all depend on high energy consumption. So the lifestyles that we currently enjoy may have to change. (I note here that I assume he’s referring to the lifestyles that are actually available to a relatively small percentage of the earth’s population—listeners to this podcast, for example.}
Thus, assuming humans survive, what life will look like is an “open question.”
Any Rays of Hope Here?
Hanson sounds like a lively, genial, upbeat guy. Remember, those tiny adaptable lizards inspired him. And the plastic squid in his book title? He didn’t discuss them in this podcast. I initially thought he might be referring to marine life that had somehow used the dreadful plastic pollution to its advantage.
When I first googled “plastic squid,” all the references were to the lures used for fishing. Wrong plastic squid.
Looking further, I realized that Hanson is referring to the squid’s ability to change–its plasticity. (Turns out these are big nasty critters–fierce predators that have even attacked scuba divers.)
Here he is describing what was learned about that plasticity after it was thought the squid had disappeared from an area completely, migrating to cooler waters:
“When the waters got warm, they responded to that heat stress by maturing in half the time, by eating different foods, by growing half as long, and by growing only half as large. So much so that …the hooks were too big to catch these small squid that were all around. Even when a fisher would haul one of these small ones up, they would think, ’Oh, it’s the juvenile or maybe another species,’ and just throw it back. But it was the plasticity of the Humboldt squid that allowed them to make a quick pivot.”
Hanson seems to have wittily reversed the common usage of “plastic squid.” Instead of a human-made item that people use to “fool” fish, he’s discussing a squid’s ability to “fool” people who fish.
I think I’ve been lured into reading his book.
Hanson likes to use the term “global weirding”: the strange and dramatic climate swings many of us are seeing quite often. His hope is that as we witness this weirding first-hand with greater frequency, we’ll finally be motivated to address the issue with the urgency it deserves—first as individuals, and then as a society.
Scientists are learning from those little lizards, he says, by adapting to our new reality. That includes focusing on how to “worry smarter”: to point the way to better allocations for research, conservation, and policy toward the ecosystems that need them the most—right now.
What Can We Individuals Do?
“Everything you can,” he says, urging us to think about how we drive, shop, mow our lawns, light our homes, dry our laundry.
When we take such steps, Hanson believes, we “feel a little better and want to do more.” The resulting “positive feedback loop” has the “cumulative power…we need to change policy.”
What do you think? Are we up to this challenge as the clock ticks away?