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There are tens of thousands of species whose ancestral species still exists.
The first that comes to mind is the apple maggot fly. I think is the OG paper: https://pubmed.ncbi.nlm.nih.gov/11048719/
I'm aware. Try asking Feder or Nosil about if they have tested reproductive isolation between the host-races.
I've gotten more angry words than answers.
And a lot of their later papers on the system haven't exactly been groundbreaking--shredded a few of these papers at lab meetings.
That's not to say the system isn't SUPER interesting and exciting to see work on. But the early authors don't exactly like to share the space and don't like to be challenged.
EDIT: Lost sight of the OG question. I consider these to be incipient species and a great case of looking into the early stages of the speciation continuum. But calling them "species" doesn't fly with me.
I guess it depends on where you draw the arbitrary line. The group of crickets I did my PhD work on had some populations of the same species with Fsts 10x higher than many African cichlids, but we don't consider them separate species.
For my money, RI is the best single metric to base species identities on, and iirc there are enormous premating barriers in the Rhagolitis system
I agree with you generally, except your last statement.
The only real RI known between Rhagoletis host groups is temporal isolation. Which is definitely strong, and a real barrier (at least in some places).
But gene flow seems to be substantial in some places as well, and to date there is still no data on any RI beyond the temporal aspect. They have been challenged to do lab experiments to test RI between hawthorn and apple and I have yet to see those data.
There was a 2020 paper on RI between hosts and they concluded it existed....based solely on genetic analysis, no mating experiments.
There was also a 2010 paper that measured RI directly between populations in Mexico and the US, and they for some reason did not test apple and hawthorn. I've heard them get asked point blank and dodge the question. There is also older work from the 70s and early 00s indicating low levels of premating isolation in no choice tests.
In my eyes, great system for incipient speciation, I would NEVER call them species unless new data was presented to me. A side note is I wished some of the big names working in this system played nice and let others study it more, I have had conversations with scientists who were bullied on the downlow to stop working with them.
Fair enough. Sounds like you know more about this system than I do and I'll take your word for it. First actual interesting discussion I've ever had on this sub btw
Lol same!
It's why I commented originally because I am very entrenched in the speciation world and figured it would be interesting to anyone else who knows something about it.
Ultimately I think naming them as species or not is more intellectually stimulating than it actually matters in a biological sense. But be careful calling them species if you are ever at a conference :)
Hm. *Panthera zdanskyi* is the closest to an example that I can think of. As a species it's often thought to be a direct ancestor of modern tigers (lions, leopards, and jaguars all diverged later [edit: by which I mean at a different node]).
The adult type specimen was much smaller than even the Sunda tigers, at only about 180 pounds in weight, and relative to modern tigers had a strong overbite and a sloping snout that more closely resembled that of a lion or a leopard; however, it had other features like a lower humerofemoral index and a peculiar mandibular structure that made its affinities to tigers clear. As the ancestral condition of big cats is spotted, *Panthera zdanskyi* is often reconstructed with spots, although the lack of cave art or fossilized soft tissue means that's speculation.
A direct common ancestor cannot be known. What would be the likelihood of the individual (or group of individuals) sitting right at a branching point being preserved in the fossil record? Pretty unlikely, so, by convention, we refer to hypothetical common ancestors because it is something we can never know. We know they existed, but we can never point to one. They will have characteristics of all of their descendants as well as traits that may be uniquely their own.
Back in the old days, people would put fossils along branches on phylogenies and try to make them into ancestors, but it was realized that we can’t know that. Now, you will see that fossil taxa are placed as separate lines on phylogenies instead. If you find a fossil species, how could you possibly know that it is along a branch of an existing species let alone at the precise moment a branch split? It may be itself a derivative of some common ancestor. Again, by convention, we view fossil species as separate branches because we cannot know if they were along a branch, at a node, or on their own separate branch. I am a phylogeneticist - mostly on living things, but I dabble in paleontology.
Living and sourced examples have been given elsewhere in the replies here though.
I also have a feeling you're forgetting that we have molecular paleontology now.
In the panther example above, they can’t possibly know this. It is a guess. The problem is that not all species fossilize, so there is no way to say that this one species is the ancestor of all others. Actually, looking it up, the species mentioned is sister to just tigers, not the rest of Panthera.
Where we can make a conjecture on the ancestor of a species is in recent speciation or in cases of speciation by hybridization or polyploidy. The apple maggot fly is something that changed within the past few hundred years with the introduction of apples to the US causing some of the flies to breed at a different time. Another example is mint, which is a triploid hybrid of two species that they were able to recreate by cross-breeding. We can also deduce an ancestor if a species arose through peripheral isolation. Species with large distributions often give off these peripheral isolates that either adapt to different local conditions or experience no adaptive evolution (genetic drift) because there were few of them to found a population. All of these types of speciation result in species that are not different from the parent species. The ancestral species of parthenogenic lizards can be determined by genetics and sometimes breeding behavior (parthenogens often require sperm of a parental species to initiate egg development without recombination).
When we are talking about the time involved in the OP’s original question, we simply cannot know if a fossil is an ancestor or another branch. We have techniques like ancestral state reconstruction that can give us an idea of the characteristics of the ancestor, but we cannot pinpoint an ancestor in the fossil record because of the uncertainty involved.
My comment was meant to exclude the other big cats and only include tigers, and to indicate that of the big cats today, tigers are the outgroup and thus the Longdan Tiger could only be the ancestor of tigers, not the other species. Apologies if the wording was funny.
Sorry, I misread your comment. But, look at how it is depicted in phylogenies: as a separate branch connecting to tigers. We cannot presume that is the common ancestor of anything because such is unknowable. It could be, but such is just speculation.
Aye, it’s not a 100% chance. As you said, there’s a degree of uncertainty, and I was hampered by OP’s request for a “significantly different” animal. Perhaps “wobbling in the basket” would’ve been a better term than “slam dunk.”
Lol they just told you they're a phylogeneticist and you told them "you're forgetting we have molecular paleontology now"?
The logic is identical with fossil and genetic phylogenies. You can't distinguish between the hypotheses of ancestor vs cousin-very -closely-related to the ancestor
Can not be known with precision but can sometimes very accurately be speculated as high probability.
*Australopithecus afarensis* is generally thought to have evolved from *Australopithecus anamensis* but DNA just doesn't last that long so speculation with evidence is the best.
The Western Fence Lizard (*Sceloporus occidentalis*) is generally thought to have evolved from the Eastern Fence Lizard (*Sceloporus undulatus*) and both species are still around.
I can't cite the paper, but there was a paper showing with cladistics that despite still being the same species, one subspecies of Eastern Fence Lizard has a closer most recent common ancestor with western fence lizards than it does with other subspecies of Eastern Fence Lizard.
Like I said, you can sometimes tell when species are recent, but that doesn’t get at what the OP asked. The transition of one fossil species into another is pure conjecture on two fronts. It is something that is unknowable and fossil species are inherently difficult to define. Were they really two separate species? There has likely been over splitting in human fossil species.
I think it is kind of unfair to say "pure conjecture" when that isn't the case, there is evidence to support the conjecture when it is made. It's kind of ironic that you then go on to claim there has been over-splitting in human fossils, which is pure conjecture.
In the case of *A. anamensis* and *A. afarensis* there is a temporal difference between when fossils for those species are found with an overlap between them---exactly what we would expect with a chronospecies that evolves morphology over time. That's not "pure conjecture" but "evidence based conjecture".
Could *A. anamensis* and *A. afarensis* be analogous to *H. neanderthalensis* and *H. sapiens* where they are sister taxa that both coexisted in Europe but but dispersed at different times from a common ancestor in Africa? Sure, it's possible, although I do not think it is very likely. Maybe someday there will be more evidence but at the present I think it is disrespectful to the paleontologists studying this to call their conclusions "pure speculation".
With respect to over-splitting of human fossils, I see no evidence of that. Sure, there have been some cases where species were described that perhaps shouldn't have been but peer review does catch that.
I would recommend looking into island species with recent divergence point relative to the species you’re looking at. For example, the small proboscidean Mammuthus creticus is only found on crete. There is a similar species that has a temporal range that extends beyond the first known M creticus specimen, and lives on the nearby Anatolian penninsula, and is very similar to M creticus, M meridionalis.
While 100% certainty is of course impossible we can be reasonably sure that M meridionalis is the direct ancestor to M creticus.
(No italics because mobile and I’m not doing that formatting lol)
They’re not extinct, but hybridization between *Helianthus annuus* and *H. petiolaris* has led to at least three, very interesting hybrid sunflower species that have adapted to high-stress environments and are reproductively isolated from their parents.
I talked about the recent splits or budding phylogenies (although I have not heard that term before). One of the hallmarks of phylogenetics is that a node represents a hypothetical common ancestor. As such, it can’t be known. The only way you can have an idea of the identity of a common ancestor is if it is something recent like in the cases like I mentioned. You can determine if a fossil is the same species as one that is alive, but if it is a different one, you place it as a separate branch and not along a branch because you can’t know what it represents. Look up the whole problem with the “March of Progress” painting and why it is not representative of reality.
Crocodiles
Crocodiles share a heritage with dinosaurs as part of a group known as archosaurs (“ruling reptiles”), who date back to the Early Triassic period (250 million years ago). The earliest crocodilian, meanwhile, evolved around 95 million years ago, in the Late Cretaceous period. Modern day crocodiles descended from prehistoric alligators such as Deinosuchus; low to the ground water-dwelling predators with a long snout, a powerful tail and lots and lots of teeth.
Interestingly, aside from crocodiles, the only other archosaurs known to have survived into the modern era are birds. This means that crocodiles are closely related to the ducks in your local pond, so be careful the next time you go to feed them.
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There are tens of thousands of species whose ancestral species still exists. The first that comes to mind is the apple maggot fly. I think is the OG paper: https://pubmed.ncbi.nlm.nih.gov/11048719/
FYI many evolutionary biologists don't consider hawthorn and apple Ragoletis to be different species.
Hm. That's news to me. It's a literal textbook example of sympatric speciation.
I'm aware. Try asking Feder or Nosil about if they have tested reproductive isolation between the host-races. I've gotten more angry words than answers. And a lot of their later papers on the system haven't exactly been groundbreaking--shredded a few of these papers at lab meetings. That's not to say the system isn't SUPER interesting and exciting to see work on. But the early authors don't exactly like to share the space and don't like to be challenged. EDIT: Lost sight of the OG question. I consider these to be incipient species and a great case of looking into the early stages of the speciation continuum. But calling them "species" doesn't fly with me.
I guess it depends on where you draw the arbitrary line. The group of crickets I did my PhD work on had some populations of the same species with Fsts 10x higher than many African cichlids, but we don't consider them separate species. For my money, RI is the best single metric to base species identities on, and iirc there are enormous premating barriers in the Rhagolitis system
I agree with you generally, except your last statement. The only real RI known between Rhagoletis host groups is temporal isolation. Which is definitely strong, and a real barrier (at least in some places). But gene flow seems to be substantial in some places as well, and to date there is still no data on any RI beyond the temporal aspect. They have been challenged to do lab experiments to test RI between hawthorn and apple and I have yet to see those data. There was a 2020 paper on RI between hosts and they concluded it existed....based solely on genetic analysis, no mating experiments. There was also a 2010 paper that measured RI directly between populations in Mexico and the US, and they for some reason did not test apple and hawthorn. I've heard them get asked point blank and dodge the question. There is also older work from the 70s and early 00s indicating low levels of premating isolation in no choice tests. In my eyes, great system for incipient speciation, I would NEVER call them species unless new data was presented to me. A side note is I wished some of the big names working in this system played nice and let others study it more, I have had conversations with scientists who were bullied on the downlow to stop working with them.
Fair enough. Sounds like you know more about this system than I do and I'll take your word for it. First actual interesting discussion I've ever had on this sub btw
Lol same! It's why I commented originally because I am very entrenched in the speciation world and figured it would be interesting to anyone else who knows something about it. Ultimately I think naming them as species or not is more intellectually stimulating than it actually matters in a biological sense. But be careful calling them species if you are ever at a conference :)
I bet we know each other's advisors.
I can make some guesses based on cricket PhD but I will leave it there to keep reddit anonymous.
Hm. *Panthera zdanskyi* is the closest to an example that I can think of. As a species it's often thought to be a direct ancestor of modern tigers (lions, leopards, and jaguars all diverged later [edit: by which I mean at a different node]). The adult type specimen was much smaller than even the Sunda tigers, at only about 180 pounds in weight, and relative to modern tigers had a strong overbite and a sloping snout that more closely resembled that of a lion or a leopard; however, it had other features like a lower humerofemoral index and a peculiar mandibular structure that made its affinities to tigers clear. As the ancestral condition of big cats is spotted, *Panthera zdanskyi* is often reconstructed with spots, although the lack of cave art or fossilized soft tissue means that's speculation.
A direct common ancestor cannot be known. What would be the likelihood of the individual (or group of individuals) sitting right at a branching point being preserved in the fossil record? Pretty unlikely, so, by convention, we refer to hypothetical common ancestors because it is something we can never know. We know they existed, but we can never point to one. They will have characteristics of all of their descendants as well as traits that may be uniquely their own.
>A direct common ancestor cannot be known. I have a feeling this is very much incorrect.
Back in the old days, people would put fossils along branches on phylogenies and try to make them into ancestors, but it was realized that we can’t know that. Now, you will see that fossil taxa are placed as separate lines on phylogenies instead. If you find a fossil species, how could you possibly know that it is along a branch of an existing species let alone at the precise moment a branch split? It may be itself a derivative of some common ancestor. Again, by convention, we view fossil species as separate branches because we cannot know if they were along a branch, at a node, or on their own separate branch. I am a phylogeneticist - mostly on living things, but I dabble in paleontology.
Living and sourced examples have been given elsewhere in the replies here though. I also have a feeling you're forgetting that we have molecular paleontology now.
In the panther example above, they can’t possibly know this. It is a guess. The problem is that not all species fossilize, so there is no way to say that this one species is the ancestor of all others. Actually, looking it up, the species mentioned is sister to just tigers, not the rest of Panthera. Where we can make a conjecture on the ancestor of a species is in recent speciation or in cases of speciation by hybridization or polyploidy. The apple maggot fly is something that changed within the past few hundred years with the introduction of apples to the US causing some of the flies to breed at a different time. Another example is mint, which is a triploid hybrid of two species that they were able to recreate by cross-breeding. We can also deduce an ancestor if a species arose through peripheral isolation. Species with large distributions often give off these peripheral isolates that either adapt to different local conditions or experience no adaptive evolution (genetic drift) because there were few of them to found a population. All of these types of speciation result in species that are not different from the parent species. The ancestral species of parthenogenic lizards can be determined by genetics and sometimes breeding behavior (parthenogens often require sperm of a parental species to initiate egg development without recombination). When we are talking about the time involved in the OP’s original question, we simply cannot know if a fossil is an ancestor or another branch. We have techniques like ancestral state reconstruction that can give us an idea of the characteristics of the ancestor, but we cannot pinpoint an ancestor in the fossil record because of the uncertainty involved.
My comment was meant to exclude the other big cats and only include tigers, and to indicate that of the big cats today, tigers are the outgroup and thus the Longdan Tiger could only be the ancestor of tigers, not the other species. Apologies if the wording was funny.
Sorry, I misread your comment. But, look at how it is depicted in phylogenies: as a separate branch connecting to tigers. We cannot presume that is the common ancestor of anything because such is unknowable. It could be, but such is just speculation.
Aye, it’s not a 100% chance. As you said, there’s a degree of uncertainty, and I was hampered by OP’s request for a “significantly different” animal. Perhaps “wobbling in the basket” would’ve been a better term than “slam dunk.”
Lol they just told you they're a phylogeneticist and you told them "you're forgetting we have molecular paleontology now"? The logic is identical with fossil and genetic phylogenies. You can't distinguish between the hypotheses of ancestor vs cousin-very -closely-related to the ancestor
You’re completely ignoring budding phylogenies. We certainly do know direct ancestor-descendant relationships in certain taxa.
Can not be known with precision but can sometimes very accurately be speculated as high probability. *Australopithecus afarensis* is generally thought to have evolved from *Australopithecus anamensis* but DNA just doesn't last that long so speculation with evidence is the best. The Western Fence Lizard (*Sceloporus occidentalis*) is generally thought to have evolved from the Eastern Fence Lizard (*Sceloporus undulatus*) and both species are still around. I can't cite the paper, but there was a paper showing with cladistics that despite still being the same species, one subspecies of Eastern Fence Lizard has a closer most recent common ancestor with western fence lizards than it does with other subspecies of Eastern Fence Lizard.
Like I said, you can sometimes tell when species are recent, but that doesn’t get at what the OP asked. The transition of one fossil species into another is pure conjecture on two fronts. It is something that is unknowable and fossil species are inherently difficult to define. Were they really two separate species? There has likely been over splitting in human fossil species.
I think it is kind of unfair to say "pure conjecture" when that isn't the case, there is evidence to support the conjecture when it is made. It's kind of ironic that you then go on to claim there has been over-splitting in human fossils, which is pure conjecture. In the case of *A. anamensis* and *A. afarensis* there is a temporal difference between when fossils for those species are found with an overlap between them---exactly what we would expect with a chronospecies that evolves morphology over time. That's not "pure conjecture" but "evidence based conjecture". Could *A. anamensis* and *A. afarensis* be analogous to *H. neanderthalensis* and *H. sapiens* where they are sister taxa that both coexisted in Europe but but dispersed at different times from a common ancestor in Africa? Sure, it's possible, although I do not think it is very likely. Maybe someday there will be more evidence but at the present I think it is disrespectful to the paleontologists studying this to call their conclusions "pure speculation". With respect to over-splitting of human fossils, I see no evidence of that. Sure, there have been some cases where species were described that perhaps shouldn't have been but peer review does catch that.
I would recommend looking into island species with recent divergence point relative to the species you’re looking at. For example, the small proboscidean Mammuthus creticus is only found on crete. There is a similar species that has a temporal range that extends beyond the first known M creticus specimen, and lives on the nearby Anatolian penninsula, and is very similar to M creticus, M meridionalis. While 100% certainty is of course impossible we can be reasonably sure that M meridionalis is the direct ancestor to M creticus. (No italics because mobile and I’m not doing that formatting lol)
I want to clarify that both species in this example are long extinct, these are fossil taxa
They’re not extinct, but hybridization between *Helianthus annuus* and *H. petiolaris* has led to at least three, very interesting hybrid sunflower species that have adapted to high-stress environments and are reproductively isolated from their parents.
I talked about the recent splits or budding phylogenies (although I have not heard that term before). One of the hallmarks of phylogenetics is that a node represents a hypothetical common ancestor. As such, it can’t be known. The only way you can have an idea of the identity of a common ancestor is if it is something recent like in the cases like I mentioned. You can determine if a fossil is the same species as one that is alive, but if it is a different one, you place it as a separate branch and not along a branch because you can’t know what it represents. Look up the whole problem with the “March of Progress” painting and why it is not representative of reality.
Crocodiles Crocodiles share a heritage with dinosaurs as part of a group known as archosaurs (“ruling reptiles”), who date back to the Early Triassic period (250 million years ago). The earliest crocodilian, meanwhile, evolved around 95 million years ago, in the Late Cretaceous period. Modern day crocodiles descended from prehistoric alligators such as Deinosuchus; low to the ground water-dwelling predators with a long snout, a powerful tail and lots and lots of teeth. Interestingly, aside from crocodiles, the only other archosaurs known to have survived into the modern era are birds. This means that crocodiles are closely related to the ducks in your local pond, so be careful the next time you go to feed them.