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> Convergent evolution is a thing, it occurs, but it's generally considered super-rare. Not anymore - though it depends on what precisely you mean by convergen

> Convergent evolution is a thing, it occurs, but it's generally considered super-rare. Not anymore - though it depends on what precisely you mean by convergence, of course. I highly recommend the new book Improbable Destinies by Jonathan Losos[0] [0]https://www.amazon.com/Improbable-Destinies-Chance-Future-Evolution/dp/0399184929 https://www.amazon.com/Improbable-Destinies-Chance-Future-Ev...

dekhn 8y ago
By convergence, I mean in the sense that two independent organisms that did not share a historical character trait (in this case, a specific homologous gene) independently evolved an identical trait (a gene with provably no homology, but identical function) through the process of natural selection, with no information sharing via horizontal gene duplication. This was argued out a while ago with stick insects that lost and then regained the ability to fly (several independent subspecies did this). A lot of people thought it meant the stick insects "completely lost all the genes associated with wing formation" and then "gained an entirely new set of genes that caused wing formation", but folks in the evo devo world believe- and I agree- that the insect never lost anything except a few regulatory domains that managed the expression of pre-existing components that are depended upon by multiple other subsystems (IE, wings are composed of basis proteins that are used for many body parts). My interest is in molecular evolution, not full character traits, because those phenotypes are incredibly complex and IMHO beyond our current level of sophistication in analysis.
- joshuahedlund 8y ago
  > By convergence, I mean in the sense that two independent organisms that did not share a historical character trait (in this case, a specific homologous gene) independently evolved an identical trait (a gene with provably no homology, but identical function) through the process of natural selection, with no information sharing via horizontal gene duplication. I'm no expert and could be wrong but I think this is what Losos is referring to in his book. For example, "New and Old World porcupines do not share a common evolutionary heritage… The two lineages have independently evolved their quills from different, unquilled rodent species." Dozens of stuff like this. He goes into more detail with tropical island anoles, his field of expertise, and orients the whole discussion around Stephen Jay Gould and Simon Conway Morris's competing views on the overall paradigm of convergence. See this NPR interview for a quick summary[0]. A key quote (which I'm not discerning enough to tell if it challenges your claims or if your claims are actually already in response to these claims): "the flood of molecular DNA data that has come forth in the last two decades or so has in many cases revised our understanding about how species are related to each other. And it has revealed that many species that we thought were similar because they're closely related, that they're not closely related and that their similarity is the result of convergent evolution." https://www.npr.org/2017/09/07/549250035/biologist-jonathan-losos-explores-convergent-evolution-in-improbable-destinies https://www.npr.org/2017/09/07/549250035/biologist-jonathan-...
  - dekhn 8y ago
    Sure, I'm not going to complain about things like quills being an example of convergent evolution. those two porcupines aren't the same species- they were ad-hoc clustered together based on phenotypic similarity. But if you investigated, you'd seen huge differences in the sets of genes required to grow quills. There's nothing surprising or interesting about that- spike shapes are common in nature and probably fall out of basic genetic evo-devo rules naturally.

dekhn 8y ago

By convergence, I mean in the sense that two independent organisms that did not share a historical character trait (in this case, a specific homologous gene) independently evolved an identical trait (a gene with provably no homology, but identical function) through the process of natural selection, with no information sharing via horizontal gene duplication. This was argued out a while ago with stick insects that lost and then regained the ability to fly (several independent subspecies did this). A lot of people thought it meant the stick insects "completely lost all the genes associated with wing formation" and then "gained an entirely new set of genes that caused wing formation", but folks in the evo devo world believe- and I agree- that the insect never lost anything except a few regulatory domains that managed the expression of pre-existing components that are depended upon by multiple other subsystems (IE, wings are composed of basis proteins that are used for many body parts). My interest is in molecular evolution, not full character traits, because those phenotypes are incredibly complex and IMHO beyond our current level of sophistication in analysis.

joshuahedlund 8y ago
> By convergence, I mean in the sense that two independent organisms that did not share a historical character trait (in this case, a specific homologous gene) independently evolved an identical trait (a gene with provably no homology, but identical function) through the process of natural selection, with no information sharing via horizontal gene duplication. I'm no expert and could be wrong but I think this is what Losos is referring to in his book. For example, "New and Old World porcupines do not share a common evolutionary heritage… The two lineages have independently evolved their quills from different, unquilled rodent species." Dozens of stuff like this. He goes into more detail with tropical island anoles, his field of expertise, and orients the whole discussion around Stephen Jay Gould and Simon Conway Morris's competing views on the overall paradigm of convergence. See this NPR interview for a quick summary[0]. A key quote (which I'm not discerning enough to tell if it challenges your claims or if your claims are actually already in response to these claims): "the flood of molecular DNA data that has come forth in the last two decades or so has in many cases revised our understanding about how species are related to each other. And it has revealed that many species that we thought were similar because they're closely related, that they're not closely related and that their similarity is the result of convergent evolution." https://www.npr.org/2017/09/07/549250035/biologist-jonathan-losos-explores-convergent-evolution-in-improbable-destinies https://www.npr.org/2017/09/07/549250035/biologist-jonathan-...
- dekhn 8y ago
  Sure, I'm not going to complain about things like quills being an example of convergent evolution. those two porcupines aren't the same species- they were ad-hoc clustered together based on phenotypic similarity. But if you investigated, you'd seen huge differences in the sets of genes required to grow quills. There's nothing surprising or interesting about that- spike shapes are common in nature and probably fall out of basic genetic evo-devo rules naturally.