How does this behavior evolve? Shrinking your internal organs and going into a zombie state for a 9-day flight seems like it would require the coordination of dozens of separate processes, and making it only 95% of the way means drowning in the ocean. Evolution works through tiny incremental changes, but this flight sounds like an all-or-nothing scenario.
I wonder if this evolved while ocean levels were lower, and the physical distances between chunks of land were shorter. And what if there were more islands along the way at some point? Also I wonder what % of godwits do actually fail along the way. I suspect that many "elderly" birds aren't able to make the trip.
I guess that death along the way is a very strong influence on their evolution. The ones that reproduce are the ones that did make the journey and have adapted to it.
Not sure about migratory birds in particular. But being able to survive without food for long periods is clearly a good trait. It has evolved across plants and animals to a lesser or greater degree. That trait can team up with another. For example an animal that can dig can hybernate underground. An animal that can fly can journey to find food or a mate. It may start by flying a short distance across land and slowly build up the distance over successive generations. Then it could learn to follow the coast to find better food. Or develop abilities for navigation. Or an instinct to fly when the days get short and be less distracted by food. Slowly but surely the benefit of flying outweighs the benefit of staying at a food source. The travel gets longer and longer until it is crossing thousands of miles.
>Evolution works through tiny incremental changes, but this flight sounds like an all-or-nothing scenario.
I never confirmed one way or the other, but I'm fairly positive evolution operates by large sudden changes followed by incremental improvements/optimizations -- it's difficult to explain many "weird" traits through incremental improvements, because most of them would get stuck in local maxima's before achieving any real benefit over the prior state.
Like you can't evolve a third arm by slowly iterating towards it, from a lump to a stump to a limb to a functional limb; it'd be entirely a loss until it becomes fully functional. You have to grow a shitty yet complete third arm first, but not so shitty that it doesn't offer benefit, and then iteratively improve it into a pretty nice arm
I think that some traits have an unreasonably large effect on the species. And we attach greater significance to them after the fact which makes it seem like a big jump. For example some fish evolved to have stubby lobed fins. That gave them some local advantage. It is just coincidental that the same change lead to arms, legs and wings.
And these kind of big visible features need more than a few changes in DNA to happen. An arm needs to attach to something, have muscles and arteries and nerves. That can only evolve iteratively from something else. There is a reason that elephant trunks are also a nose.
> I never confirmed one way or the other, but I'm fairly positive evolution operates by large sudden changes followed by incremental improvements/optimizations
This is basically the theory of punctuated equilibrium as proposed by Stephen Jay Gould to the commonly held thought at the time of gradualism.
Yes, this should be impossible -- scientists have no idea how they do it:
"Current models say the birds should conk out after three or four days, yet they fly for more than a week. “We can’t explain the physiology that allows them to do this,” Dr. Guglielmo said. “We know what the energy costs should be from wind tunnel experiments, but when we try to use our models, the energy costs we know they used are much lower.” The birds use half or less of the energy expected."
“Are they going into a suspended animation state when they are doing these monster flights?” Dr. Guglielmo asked. “I don’t think they are in a normal physiological state when they are doing this,”
It reminds of that study recently that found dead troutcan still "swim" in water currents. Perhaps these birds have similarly incredible geometry that allow them to fly without exerting energy
Apparently they flap their wings for the entire trip.
Also: "Their internal organs undergo a “strategic restructuring” before departure. The gizzards, kidneys, livers and guts shrink to lighten the load for the trans-Pacific journey. Pectoral muscles grow before takeoff to support the constant flapping the trip requires."
"Other birds do stay aloft for long periods using a technique called “dynamic soaring,” while godwits power themselves by continuous flapping, which takes far more energy."
I'm really curious about the evolutionary path these birds may have taken to an adaptation that allows them to fly 8-10 days non-stop. A couple ideas, assuming that any change evolution can keep up with needs to be gradual/incremental:
Could they have been making this journey since the land masses in question were significantly closer together?
Could they have originally migrated between closer locations, but as weather warmed post-ice-age they slowly increased the length of migration between "temperate northern hemisphere" and "temperate southern hemisphere" climates?
Could sea level rises post-ice-age have covered over islands that were formerly stopping points, or pushed back shorelines that effectively increased the distance required?
Curious to hear what other ideas folks might have.
I just asked the same question -- it would be interesting to see how long ago these land masses were close enough together and the rate at which they moved apart over time.
If you count direct flights with stops (eg, it stops, but you stay on the plane), then the longest on an LCC is French Bee that'll take you from Paris to Papeete (Tahiti) via LA. Food not included on the Basic Fare, with a scheduled duration of 19:55 to fly 15,728 km.
There’s a Wikipedia article of longest flights that I’m pretty familiar with, and I looked through that seeing if I could find a LCC in the list because I was curious
> “The more I learn, the more amazing I find them,” said Theunis Piersma, a professor of global flyway ecology. “They are a total evolutionary success.”
Amazing animals indeed, but the latter is a strangely unscientific thing for any kind of biologist to be quoted saying.
I wonder if this is one of those journo-quotes:
Journo: "Would you say these birds are a total evolutionary success?"
Biologist: "Well, I wouldn't put it like that, but yes, they show an incredible adaptation ... <etc>"
Yeah, the idea that they are a total evolutionary success only makes sense if you start by assuming that they must be a total evolutionary success. It makes just as much sense to say they are a brilliant example of intelligent design.
The concept of 'total evolutionary success' doesn't really make any sense.
The species is not extinct, but so is every other extant species. Maybe gene frequency is your success measure? There aren't many of this species around. Some of its genes are found in all birds, so those are pretty successful, but small beans compared to ant or algae genes. All these things probably have some respiration or protein synthesis genes in common. Maybe the success is with respect to their ecological niche? They fly really far! But everything lives in its own niche, and is the same amount of alive in it....
Evolved things are not more or less successful, they just are.
I wonder if any small insects have learned to hitch a ride in the feathers of these birds in order to reach far away lands. I guess their lifespan wouldn’t allow for such a long journey unless perhaps they went into some kind of hibernation.
