by Lawrence Joe
Models we learn about in the classroom, such as evolution, are very useful in helping us organize how things behave in this complicated world. They help us notice patterns and make predictions and organize and guide us in the direction of the truths we are looking for. But, in the real world, they work in much more complex and often less clear cut or straightforward ways.
When I watched Anthony Lapsansky’s talk on lesser-known transitions in diving birds, I was reminded of this. Anyone who’s ever read any sort of biology textbook ever will know about the idea of form and function. The physical and chemical make-up of an organism is always paired with completing a specific task which (theoretically) increases fitness. And so, as we look out into the real world, this is a useful idea to consider when trying to understand why the natural world exists as it does. But, yet again, it gets even more complicated than that.
As Mr. Lapsansky states in the introduction to his talk, very rarely is there ever simply one function for every form. More often, multiple functions are paired with a single form.
“Multifunctionality is almost certainly the norm rather than the exception to the rule.” he states.
This is also the case in Lapsansky’s choice of case organism: diving birds. Diving birds are a good choice in studying multifunctionality for many reasons, but perhaps the most significant is that the big multifunctionality that they exhibit is completely physical. They have to effectively navigate through two different types of fluids, air and water, with the same body plan. “The laws of physics don’t change with the individual or the age or the relative abundance of resources or mates”, and therefore it’s much easier to understand the sort of tradeoffs that comes with this multifunctionality. Water is also a very harsh environment for a creature that relies on lungs.
“In exploiting an environment in which an animal cannot continually survive – the ramifications of being inefficient are perhaps more tangible than in any other behavior”. Lapsansky tells us.
Combine this with the diversity of species that exist and the different strategies that exist among diving birds for locomotion, and we have a good avenue for exploring what sort of evolutionary trade-offs may exist. The surprising thing is exactly what sort of morphological differences there are.
In this study, Lapsansky specifically studies the wings of diving birds. And the difference is wing size, but not because they are being used differently in water as both wing divers and foot divers have smaller wings, or because they’re used differently in air in the wide-open environment that they inhabit, but because it reduces the amount of air trapped inside the wings that slows them down burns extra energy as they try to dive.
“…buoyancy constitutes one of the major costs if not THE major cost to diving in a bird”. he says.
Now this is not for sure, nothing is, but it is interesting for several reasons. First, it is a unifying difference across many different iterations of evolved avian diving, and secondly it has nothing to do with how they’re being used necessarily. Rather it is simply a product of the wings being present. But as is always the case, it’s important to note that this is only one suggested hypothesis for an observed pattern that is consistent with this data and that we cannot know why it actually is the case.
And this is one reason why science is so amazing
. Because the answer could have nothing to do with the ways that we think it is, but it also is exactly the reasons that make the most sense. A complex, demanding system, and maybe the answer is just so simple. So, even though the world is a complicated place, there can still be very simple solutions to it.
Lapsansky was awarded the DCB Oral Presentation—Mimi A. R. Koehl award- Anthony Lapsansky for 2021 ,he has work in progress with ICB on his talk for SICB, & he had a co authored paper of Lapsansky’s was also cited in 2019’s Multifunctional Structures and Multistructural Functions: Integration in the Evolution of Biomechanical Systems by Farina et al https://doi.org/10.1093/icb/icz095
connect with Anthony via
https://lapsansky.org/resume/ & @PhysicksofLife on Twitter
Blogger Lawrence Joe, was part of SICB’s 2021 high school initiative encouraging up and coming science communicators
ICB free read on related topic
Secondary Evolution of Aquatic Propulsion in Higher Vertebrates: Validation and Prospect
by Frank E. Fish
“Re-invasion of the aquatic environment by terrestrial vertebrates resulted in the evolution of species expressing a suite of adaptations for high-performance swimming. Examination of swimming by secondarily aquatic vertebrates provides opportunities to understand potential selection pressures and mechanical constraints, which may have directed the evolution of these aquatic species…”