Geology imprinting on biology: examples?

I’ve heard the story about migrating monarch butterflies pulling a couple quick turns during the middle of their flight across Lake Superior to – well, fly around a mountain on that pathway that used to be there.

If that’s true, are there any other examples out there where lifeforms exhibit odd behavior as a clue to a long past geological reality?


What happened to the mountain?


This is something that I never really paid attention to in the past but has cropped up recently. I was at a conference where one of the speakers gave an overview of the 14 natural land divisions in my state (IL, US). It was interesting but I didn’t really give it further thought until I noticed that there was a Bumble Bee species that had very few observations in one of the divisions: Bombus rufocinctus is not recorded often at all in Wisconsin Driftless Area in any of the four states (IL, WI, MN, IA) that contain Driftless. The Driftless area is basically a region that was pretty much unaffected by any of the glacial advances.

Another example is Xylocopa virginica. Few if any records in the Driftless area, and east of that is the Rock River Hill Country, even there the observations are scare and are all along the border of the next division: Northeastern Moraine where they are common (and where I am). The Moraine was heavily influenced by the glaciers.

What I find very interesting about this is both of those species are generalist pollinators and I would think that agricultural and urban changes and the spread of introduced plants would make land divisions less impactful as range barriers.

I realize that by using iNat data I am potentially ignoring the possibility observer inconsistency (Northeastern Moraine has a much higher human population than the other 2 divisions), but the Bumble Bee also shows a similar range in Bumble Bees of North America. Would love to read more about this if anyone knows about papers I can read.


This conclusion seems so surprising that we should be able to find the research paper behind it. It evidently also seemed a little dubious to people on Reddit who pointed out that erosion typically happens on a much slower timescale than would be needed for Monarchs to have imprinted a now-eroded mountain in their inherited route maps.

Other commenters suggested that the scale and recency of the last major glaciation in North America might make it possible for a migration-blocking mountain to be demolished within the last 50,000 years. Then again, if Monarchs previously migrated around a mountain that was destroyed by the advance of glaciation, where exactly were they migrating to and from at a time when everything north of Chicago was covered by the Laurentide Ice Sheet?

A web search turned up several articles from 2013 or later that summarize the claim. This one appears to be the first of them:

That article references Annie Dillard’s 1974 book Pilgrim at Tinker Creek and an article from The Journal of Experimental Biology via a broken url. It seemed that I might be getting close to the actual research behind the claim. A bit of tinkering suggests the article in question is this one:

“Monarch butterfly orientation: missing pieces of a magnificent puzzle”
Lincoln P. Brower, The Journal of Experimental Biology 199, 93–103 (1996)

Great, except that Brower’s paper doesn’t mention anything about a dogleg in Monarchs’ route as they migrate over Lake Superior. The migration data reported in the paper is much more coarse in scale, and Brower’s big idea is a hypothesis that a daily shift of 1 degree in flying direction could explain Monarchs’ ability to complete a migration cycle over multiple generations.

I’m still looking for the actual source of this nugget of supposed knowledge, but I think it has to have surfaced some time between 1996 and 2013.


I have been reading A World on the Wing by Scott Wiedensaul. His chapter on Kirtland’s Warbler seems to be something like what you are asking.

Kirtland’s Warbler historically nested in only a few counties in the “mitten” of Michigan, in Jack Pine thickets of a certain age range (they have only recently expanded into Wisconsin). They winter on only some of the Bahamas. This unusual range seems to be a relic of the last glaciation: sea levels were lower, so the Bahamas were larger; meanwhile, the Jack Pine ecosystem was in the Southeast. It was a fairly short migration then. As the glacier melted, and the Jack Pine ecosystem gradually shifted to the Upper Midwest, the warblers migrated increasingly far to reach their familiar nesting habitat, while remaining imprinted on the Bahamas (shrinking as sea level rose) for the winter.

Another example is earthworms, which are considered to be introduced and invasive in places that were glaciated during the last ice age. They didn’t naturally expand into those areas after the glacier melted.


You may be familiar with “California ring species”, Salamanders (Ensatina eschscholtzii and its subspecies) being one of the best examples but there are many species that follow this pattern.

If you’re not familiar you should definitely look it up but basically species that are found in the Sierra and coastal ranges of CA have subspecies that are closely related as you move up the Sierra and across to the coast, because there is pretty much contiguous habitat. In SoCal the Mojave desert creates a break in the ring that (generally) prevents the southern CA populations from meeting up with the Sierra populations, so despite being geographically close the populations are (generally) genetically distant.

My favorite example of this is in trapdoor spiders. They follow this pattern really closely because they are big clunky spiders that generally don’t disperse very far. But there is an odd exception were a species in the coastal range near Monterey is most closely related to a species near Yosemite instead of being most closely related to it’s nearest coastal range neighbor. But there is evidence of an ancient river that used to cut through the central valley of CA that lines up well with these two species, suggesting that the river may have dispersed the spiders across the valley and deposited them near the coast which would explain why the evolutionary tree for this group of species doesn’t perfectly follow “the ring”.


I have a very strong suspicion that the migration of Globe Skimmer Dragonflies (Pantala flavescens) from India to Africa, and back again, a route seemingly unfeasible to have come about considering the distances and lack of fresh water available, originated when India and Africa were far closer together.

The incremental distances the landmasses would have moved apart by annually would make little difference on a short temporal scale, but on a geologically relevant scale this could easily lead to the very long migration routes we see today.

Pantala flavescens appears to have diverged around 125 million years ago. 110 million years ago India was just off the coast of Africa and still joined with Madagascar. That’s some 15 million years after the estimated species divergence dates and would have been a short distance for either the current species, or their ancestors (if they’ve significantly changed over time) to migrate.

I very much think that this migration path is a direct result of continental drift being written into species behaviors.

Similarly, mite harvestmen (a tiny relative of the larger ‘daddy long-legs’ harvestmen’ do not disperse well, so they’ve been usd to track continental drift. Turns out that the ones native to Florida are more closely related to the ones in West Africa than to the others in North America.

This is because Florida is a chunk of Africa that was ripped away one of the times the Atlantic opened, and the piece of land that became Florida carried some mite harvestmen with it.


In the Inselbergs of the southern Free State province in South Africa, the cappings of some of these formations consist of sandstone rock which around 700+ million years ago, underwent extreme chemical and structural volatility owing to ancient granitic intrusions which stopped mere 100’s of meters below the earths surface. This resulted in a mountain surface which was covered in subtle pinnacles and hollows which when moist, serve as the perfect environment for the growth of mosses and bryophytes. On these mountains, you can find a species of frog which is otherwise very common in the rest of the landscapes in South Africa, but the particular populations on these mountains have adapted to use the tiny grottos and gaps between the moss growth and tuberculated stone as optimal hiding places from their normal predators, to such an extent that when you follow the call of the frog to the exact spot, you may be standing directly above the frog without even knowing it

I wager that if the frogs in this population were removed from this habitat and placed in a standard montane grassland nearby, they would all be picked off by predators within days as their behavioural machinery cannot adapt to the absence of these uniquely crafted hiding spots

A very fascinating example then on how geology can influence vegetation, and in so doing, influence the behaviour of small insectivores

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Thanks. I tried to find hard proof too, but no luck. Might just be part of vintage disinformation born of a poetic ‘flight of fancy’.

But that is not to discredit other possible geo-echo evidence out there, as some of these other stories suggest.


Florida is built on a tiny chunk of african plate but would it have really had any land on it? To my knowledge liveable land only really began to form on it during the Oligocene-Miocene when enough limestone piled up
Cyphophthalmi are like, really chronically understudied like most tiny dirt bugs so I’d probably imagine they might have instead come via island hopping one way or another via south america, because I’d imagine there might be some more weird gondwanan relicts in north america if what became florida actually carried enough land if any

You can look up Dr Giribet’s work on the subject. Researching mite harvestmen has been a major focus of his work. According his his findings they’re most closely related to west African species, not to anything else in the Americas, and their dispersal is so slow that island hopping doesn’t appear to be a good option in any event.

It’s certainly the case that for much of the time what’s now Florida, and part of southern Georgia, was mostly underwater, with perhaps only a few very small islands making up the area, so, assuming that Dr Girbet is correct, it would have been a small initial population.

One of the issues with other species that are found with close relatives on both sides of the Atlantic is that they all tend to have a much better ability to disperse, and often are more tolerant to a wider variety of habitats, complicating the over-all dispersal timing picture for them.

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I always thought it was so cool that when you trace the phylogeny of Hawaiian endemic Drosophila, they trace back to ancestors that lived on islands that are eroded away and underwater now.


He died (again) fighting the Hound.


This is more of an interesting distributional observation relating to geology, but in Northern Virginia and adjacent US states there are 2 common species of skinks, the five-lined skink and the broadhead skink. The broadhead skink is much more common in certain geological regions, especially the Triassic Lowlands and Upper Piedmont regions. In some areas it is the only skink species present. In many other areas the five-lined skink is the only skink species present.

Here’s the regions I’m referring to:

Here’s a map of broadhead skink observations:

And here’s a map of five-lined skink observations:


2376 notifications! I thought I had it bad when it hit 300 once.


The Cypress Hills in S. Canada also have species that were left from the Glaciation. It’s quite fascinating, really. I have also read about the area you mention as well.
Donald Lafontaine (1982) (Paywall - I photocopied a copy when I was leaving Ag. Can in the mid 1980’s) believes that there are several disjoint populations of Euxoa spp. isolated by the glaciation.
I don’t know of any specific organisms that migrate and avoid specific ‘obstacles’, but it’s a fascinating idea!
BTW, Google Scholar is a good source to look up articles on arcane items of scientific interest! Bee name plus Driftless area may throw up some interesting papers.


I wrote a piece for Bay Nature about the mysterious Santa Clara County population of red-bellied newts (Taricha rivularis). It’s a species that seems to always return to the same breeding spot year after year, and it’s interesting that this population (which I’m pretty sure was introduced somehow, although there’s no smoking gun) is able to breed fine in the area.

Interestingly the Santa Cruz Mountains are also home some other disjunct salamander populations.


Here’s a link to the paper that avoids the paywall.

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Someone must have mislabeled the file. The description is " Lafontaine, J. D. (1982). BIOGEOGRAPHY OF THE GENUS EUXOA (LEPIDOPTERA: NOCTUIDAE) IN NORTH AMERICA", but the actual article is the pesticide paper. Odd.

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