Molecular biologist.
It’s mostly a matter of what we don’t know. Paleontological evidence certainly shows that horseshoe crabs didn’t change much in their appearance. However, we just don’t know to what extent other aspects of their biology are as conserved. Therefore, it is just unscientific to say that horseshoe crabs are ‘living fossils’ or that they didn’t evolve for millions of years. They may have, they may not have
I would have to assume there’s some ecological pressure they’re either experiencing or shielded from. If they’re under environmental pressure, they are either exceptionally developed to endure environmental changes or they’re adapting to the environment in ways that don’t reflect in their physiology. If they’ve just found a niche biome where the ecological conditions are fairly static, and they’re well suited to the environment, what changes would you see other than some generic genetic drift?
It makes sense. I just wasn’t sure how likely it would be for species to evolve in significant ways over a long time without obvious changes to the shape of their fossils. Difficult to spot evolution happens a lot, apparently:
Cryptic, or sibling, species are discrete species that are difficult, or sometimes impossible, to distinguish morphologically and thus have been incorrectly classified as a single taxon. Cryptic species are found from the poles to the Equator and in all major terrestrial and aquatic taxonomic groups [2, 3]. For example, a recent meta-analysis yielded 2,207 articles reporting cryptic species in all metazoan phyla and classes, including 996 new species in insects, 267 in mammals, 151 in fishes and 94 in birds [2].
Yeah exactly. I’m not a biologist but I am aware that horseshoe crabs are harvested for their blood and its unique properties. How much evolution (in the last 450MY) have they undergone in terms of their immune system and other microbiological processes? We may never know but I think it’s quite a stretch to assume “none!”
Absence of paleontological evidence of change in appearance does not mean evolutionary stagnation
Doesn’t it? It doesn’t seem obvious either way. Are you an actual paleontologist, or just guessing?
Molecular biologist.
It’s mostly a matter of what we don’t know. Paleontological evidence certainly shows that horseshoe crabs didn’t change much in their appearance. However, we just don’t know to what extent other aspects of their biology are as conserved. Therefore, it is just unscientific to say that horseshoe crabs are ‘living fossils’ or that they didn’t evolve for millions of years. They may have, they may not have
I would have to assume there’s some ecological pressure they’re either experiencing or shielded from. If they’re under environmental pressure, they are either exceptionally developed to endure environmental changes or they’re adapting to the environment in ways that don’t reflect in their physiology. If they’ve just found a niche biome where the ecological conditions are fairly static, and they’re well suited to the environment, what changes would you see other than some generic genetic drift?
I came to mention the same. Static phenotype ≠ static genotype.
If anyone else is struggling, this reasonably basic article helped me https://sciencenotes.org/genotype-vs-phenotype-definitions-and-examples/
Much obliged ! I was just thinking these strings of letters kinda looked like words
Honestly, I’m pretty sure they post any old brain rot here and then have an AI fabricate supporting articles online just to mess with us…
Sorry! We’re both biologists, we get nerdy.
No I love it - that’s why we’re here.
I learned something today and hope to gently explain it to my degenerating/conservative father (but let’s not get into that kettle of fustercluck!)
Makes me wonder, would epigenetic speciation be possible?
It makes sense. I just wasn’t sure how likely it would be for species to evolve in significant ways over a long time without obvious changes to the shape of their fossils. Difficult to spot evolution happens a lot, apparently:
Yeah exactly. I’m not a biologist but I am aware that horseshoe crabs are harvested for their blood and its unique properties. How much evolution (in the last 450MY) have they undergone in terms of their immune system and other microbiological processes? We may never know but I think it’s quite a stretch to assume “none!”
One minute earth just did a great video about that https://youtube.com/watch?v=_skYZFmr0Lg