This episode, we’re stepping back to the golden age of natural history podcasting by resurrecting the format of the classic show Wild Ideas: The Podcast. Joining us on the trail is one of the OG hosts: the man himself, Gordon Maupin. It’s a 3-way team-up where each of us brings a heavy-hitting seasonal mystery to the table.
First, Steve unravels the rule-breaking world of the Ambystoma polyploid salamander complex, where unisexual lineages are mixing up DNA from different species and blurring the lines of what makes a species a species. Then, Gordon shrinks things down to look at the world of duckweed ecology, a group that includes the smallest flowering plants in the world. Finally, Bill turns our eyes to the skies over the marsh to pull back the curtain on dragonfly migration, looking into the recent science that shows some dragonfly species are multi-generational continental travelers (as well as badass predators).
Come listen in as Gordon and the guys answer the question, “What’s going on outside?” (Wild Ideas fans, that’s for you)
This episode was recorded at the Iroquois National Wildlife Refuge in Alabama, NY on May 13, 2026.
Episode Links
Check out the Iroquois National Wildlife Refige and their Bald Eagle Cam.
Here’s the New York Times article about 7 Podcasts About the Joys of Bird Watching that includes a mention of our show.
Episode Notes
Getting The Great Egret’s Latin Name Right
During a quick aside this episode, Gordon spotted a Great Egret and Steve tried to recall its scientific name, tentatively going with Erodea alba. He wasn't entirely wrong! The correct name is Ardea alba.
While alba means "white," Ardea is Latin for "heron." It also ties back to the ancient myth by everyone’s favorite Roman poet Ovid, who wrote about a bird rising directly from the ashes of the burned city of Ardea.
What’s the Deal With Axolotls?
We wondered if the axolotl is in the same genus as the Jefferson and blue spotted salamander (Ambystoma) and yes they are!
Species: A. mexicanum (Axolotl)
Unlike most members of Ambystomatidae—which typically metamorphose into terrestrial adults—the axolotl exhibits a trait called neoteny (or paedomorphosis). This is where an organism retains juvenile or larval traits into adulthood. Axolotls retains its aquatic, larval features (like its signature feathery external gills) into adulthood and spends its entire life in the water
Bill’s Hard Claim on ID’ing Jefferson Salamanders
Bill said there is no way we could tell if it was a Jefferson salamander: is that true? Bill was basically right if we’re talking about visually confirming a female-looking salamander in a blue-spotted/Jefferson overlap zone. Many unisexual individuals cannot be confidently identified by sight, and genetic testing is the clean answer. But during the breeding season, a male with a swollen cloaca is not part of the all-female unisexual lineage, so that can help narrow things down. So, a male in breeding condition can sometimes be identified much more confidently than a female/unisexual-looking animal, but you need to have serious knowledge about species location, morphology, and breeding-season characteristics.
The Jefferson Complex vs. the Bigger Unisexual Salamander Situation
During the episode, Bill had a “wait, what are we even talking about?” moment while Steve was explaining the huge all-female/unisexual Ambystoma salamander lineage.
Steve was talking about the big-picture version: a bizarre evolutionary group that can involve genomes from several mole salamander species, including Blue-spotted, Jefferson, Small-mouthed, Streamside, and Tiger Salamanders.
Bill, though, was thinking what we hear more about in the Northeast and Great Lakes region: the “Jefferson complex,” or the Blue-spotted/Jefferson Salamander mess. Around here, that usually means you can’t usually ID a Jefferson Salamanders or a Blue-spotted Salamander down to species because the sally in front of you may belong to the all-female, polyploid lineage that can’t be confidently sorted out just by looking at them.
So Bill’s question was basically: “Hold on. Is this identification nightmare only a Jefferson/Blue-spotted thing, or does it happen with the other species too?”
And the answer is: yep. It can happen with the others too.
The narrower Jefferson complex usually refers to the Blue-spotted/Jefferson part of the story, especially in places where those are the main overlapping species. But when scientists zoom out and include the other players (Small-mouthed, Streamside, and Eastern Tiger Salamanders) they usually refer to the whole thing as the unisexual Ambystoma lineage.
So the practical field takeaway is this: in places where these species overlap, a female-looking Ambystoma salamander may be impossible to identify with confidence by appearance alone. Even experts may only be making an educated guess unless they use genetic testing. Measuring red blood cell size can help estimate ploidy (basically, whether the animal has extra chromosome sets) but DNA testing is the real way to know which genomes are actually in there.
Is Duckweed the Smallest Flowering Plant?
Yes, but specifically one type of it. The world's smallest flowering plants belong to the genus Wolffia - Often referred to as "rootless duckweed" or "watermeal," they are the tiniest members of the duckweed family (Lemnaceae)
Individual Wolffia plants are usually less than 1 mm long, roughly the size of a pinhead or cornmeal, and the flowers are correspondingly microscopic.
Unlike standard duckweed (Lemna), Wolffia plants do not have roots and appear simply as tiny floating green spheres or oval seeds.
The plant produces the world's smallest flower, which forms in a tiny depression on the plant's top surface.
Because they are so small and have highly efficient asexual budding, they can easily cover a pond in dense mats before you ever notice an individual plant. Can be found across temperate and tropical regions of North, Central, and South America
Correction: Ed Yong’s An Immense World (UV, not Infrared)
During the episode, Bill mentioned Ed Yong’s phenomenal book, An Immense World, and noted that researchers are increasingly discovering how many animals can see in the infrared spectrum. His memory slipped slightly on this one! Yong actually discusses the growing scientific realization that many animals see in the ultraviolet (UV) spectrum, not infrared. (Though as you'll see below, dragonflies do have a few tricks up their sleeves on the other end of the spectrum).
Gordon's Question: Infrared Vision & Dragonfly Mating
Bill’s misremembering of what was in An Immense World was prompted by Gordon asking a fantastic question during the recording: Can dragonflies see in the infrared spectrum, and if they can, are they using it to navigate during migration?
First, a quick clarification: when most of us hear “infrared,” we immediately picture thermal imaging — animals glowing in the dark, Predator vision, that whole thing. That is not what we’re talking about here. Dragonflies do not appear to see heat signatures.
What they may be able to see is near-infrared — light just beyond the deepest red wavelengths visible to humans. Near-infrared is not heat vision. It is more like an invisible extension of red.
According to a recent study published in January 2026 by researchers in Osaka, Japan, some dragonfly species have visual pigments that are sensitive to extremely long red wavelengths, possibly reaching into the near-infrared edge of the spectrum. That alone is pretty wild. But the discovery also highlights a striking example of parallel evolution between insects and primates. Millions of years ago, the ancestors of humans and other primates evolved molecular changes that helped produce red-sensitive vision. This new research suggests that some dragonflies may have independently evolved a similar molecular tuning mechanism for detecting red light. However, while primate red vision operates within the visible spectrum, some dragonflies appear to have pushed that sensitivity even farther, toward the boundary between deep red and near-infrared.
So what are they doing with this ability? Probably not navigating migration, at least as far as we know.
The better-supported idea is that this long-wavelength vision helps dragonflies identify mates quickly in flight. Male and female dragonflies can reflect red and near-infrared light differently, especially against green vegetation. So for an animal making split-second decisions while zipping around at high speed, that extra visual contrast could be a big deal.
So to answer Gordon’s question, dragonflies may be seeing farther into the red/near-infrared edge of the spectrum than we can, but based on what researchers currently know, they’re probably using that ability for rapid sex recognition, not long-distance navigation. It’s more of a high-speed dragonfly dating filter than infrared GPS.
The Missing Piece: Visual Cues and "Leading Lines" in Migration
One big element Bill neglected to mention in covering how dragonfies navigate during migration is the VISUAL piece – that they also use what they’re seeing! That is a crucial piece of the puzzle.
Dragonflies are also extremely visual animals. Those huge compound eyes are not just for decoration. So, what they’re seeing is likely a key piece in their migration toolbox.
Migrating dragonflies are often observed moving along major landscape features: coastlines, mountain ridges, river valleys, and other long, continuous edges. Biologists sometimes refer to these kinds of features as leading lines, because they can help guide or funnel migrating animals across the landscape.
That doesn’t mean a dragonfly is looking down and thinking, “Ah yes, the Susquehanna River. I’ll take this south.” But these landscape features can still matter in several ways.
Coastlines can keep migrants from drifting too far over open water, which is risky for an insect that eventually needs to land, rest, and feed.
Mountain ridges and long hillsides can create useful air currents and updrafts, allowing dragonflies to ride favorable winds and conserve energy.
River corridors can provide both a visual pathway and good stopover habitat, with water, vegetation, and plenty of small flying insects to eat when they need to refuel.
The overall migration story for dragonflies probably isn’t “dragonflies have one magic compass.” It’s more like they are combining a bunch of cues at once: the visual structure of the landscape below them, as well as the elements covered during the episode.
Steve's Questions: Resident vs. Migratory Green Darners & The Thermal Genetic Switch
During the episode, Steve asked two really good questions about Common Green Darners: if some are migratory and some are resident, how do they know which group to mate with? And could temperature be the thing that nudges a young darner down one path or the other?
The first answer is surprisingly simple: they probably don’t know, and they probably don’t care.
For a long time, researchers assumed these groups were reproductively isolated, believing residents emerged and died before the migratory cohort reached adulthood, but modern research has overturned this idea. According to a comprehensive review by Michael L. May and John H. Matthews, adult flight periods absolutely overlap in mid-summer, and genetic testing reveals zero genetic differentiation between the groups. The entire continental population belongs to a single, randomly mating gene pool.
So when a Common Green Darner is ready to mate, it is probably not checking whether the other darner is from the “resident” or “migratory” team. It is just mating with another mature Common Green Darner in the same airspace. Very romantic. Very dragonfly.
Steve’s second question gets at something even more interesting: what makes one generation migrate while another stays put?
This is where temperature, day length, and seasonal timing seem to matter a lot. A Green Darner nymph developing in warm water during long summer days may be pushed toward faster development. That can produce adults that emerge, feed heavily, build up energy reserves, and migrate south in late summer or fall.
But if nymphs are developing as temperatures drop and days get shorter, their development can slow down. Instead of rushing to become adults, they may overwinter as aquatic nymphs and emerge the following year. Those individuals can then become part of the resident breeding population in northern ponds.
So Steve’s instinct was basically right: environmental conditions appear to play a huge role in shaping whether a darner develops quickly and migrates, or slows down and overwinters.
The only thing to be careful about is the phrase “genetic switch.” There probably are changes in gene expression involved. Temperature and day length can absolutely affect how insects develop, but in Common Green Darners, we should probably think of it less as a single switch being flipped and more as a whole developmental pathway being shaped by the environment.
The short version: migratory and resident Green Darners are not separate species or rival dragonfly factions. They appear to be part of one big, mixed population whose life cycle can play out in different ways depending on timing, temperature, and local conditions.
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Works Cited
Hallworth, M. T., Marra, P. P., McFarland, K. P., Zahendra, S., & Studds, C. E. (2018). Tracking dragons: stable isotopes reveal the annual cycle of a long-distance migratory insect. Biology Letters, 14(12), 20180741. doi: 10.1098/rsbl.2018.0741.
Hu, G., Lim, K. S., Horvitz, N., Clark, S. J., Reynolds, D. R., Sapir, N., & Chapman, J. W. (2016). Mass seasonal bioflows of high-flying insect migrants. Science, 354(6319), 1584–1587. doi: 10.1126/science.aah4379.
Knight, S. M., Pitman, G. M., Flockhart, D. T. T., & Norris, D. R. (2019). Radio-tracking reveals how wind and temperature influence the pace of daytime insect migration. Biology Letters, 15(6), 20190327. doi: 10.1098/rsbl.2019.0327.
Lancaster, L. T., Dudaniec, R. Y., Chauhan, P., Wellenreuther, M., Svensson, E. I., & Hansson, B. (2016). Gene expression under thermal stress varies across a geographic range expansion front. Molecular Ecology, 25(5), 1141–1156. doi: 10.1111/mec.13548.
May, M. L. (2013). A critical overview of progress in studies of migration of dragonflies (Odonata: Anisoptera), with emphasis on North America. Journal of Insect Conservation, 17(1), 1–15.
May, M. L., & Matthews, J. H. (2008). Migration in Odonata: a case study of Anax junius. In A. Córdoba-Aguilar (Ed.), Dragonflies and Damselflies: Model Organisms for Ecological and Evolutionary Research (pp. 63–77). Oxford University Press.
Sato, R., Terakita, A., & Koyanagi, M. (2026). Dragonfly red opsins share a common tuning mechanism with mammalian red opsins and further enhancement of near-infrared sensitivity. Cellular and Molecular Life Sciences.
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Yong, E. (2022). An Immense World: How Animal Senses Reveal the Hidden Realms Around Us. Random House.