7 ms·

The definition of what constitutes a species is a human construct. Two bird populations living in the same locale but divided by a mountain range therefore not

by greazy 6mo ago

The definition of what constitutes a species is a human construct. Two bird populations living in the same locale but divided by a mountain range therefore not naturally breeding with each other would classify as a different species, even if they could breed with each other. So your question is hard to answer.

nelox 6mo ago
I’ve often dreamt of breeding with that mythical bird far, far away.
- greazy 6mo ago
  If you do cross the barrier, you could successfully mate with that mythical bird!
deleted 6mo ago
[deleted]
John7878781 6mo ago
> Two bird populations living in the same locale but divided by a mountain range therefore not naturally breeding with each other would classify as a different species, even if they could breed with each other. Really? I thought the requirements for species classification were: (1) must be able to reproduce and (2) offspring must be fertile. Is it less objective than that?
- Archelaos 6mo ago
  Polar bears can have furtile offspring with grizzly/brown bears. See: https://en.wikipedia.org/wiki/Grizzly%E2%80%93polar_bear_hybrid https://en.wikipedia.org/wiki/Grizzly%E2%80%93polar_bear_hyb...
  - rolph 6mo ago
    the reproductive incompatability, is based on physiological range. in general, there are multi organizational levels of reproductive incompatability. in this case, the geographic distance, orogenic blockade, and ecological confounds of arctic conditions preclude easy mingling of U.arctos x U. maritimus.
- whycombinetor 6mo ago
  Interfertility is not an equivalence relation, does not form equivalence classes https://en.wikipedia.org/wiki/Ring_species https://en.wikipedia.org/wiki/Ring_species
- rcxdude 6mo ago
  There are a lot of subtleties. Ring species are a particularly fun one: you can have a population that live around some natural obstacle (like a large body of water) where individuals can breed successfully with individuals near to them but not with ones further way (like directly across the barrier), in a continuum of variation.
  - lemonberry 6mo ago
    "Ring species are a particularly fun one" This is really interesting, thank you. I've never heard of "ring species" before.
- joshuahedlund 6mo ago
  Sometimes it’s hard to objectively tell whether two animals don’t appear to reproduce because they are unable genetically, or technically able still but behaviorally unwilling in normal natural circumstances, or we don’t know but we just haven’t observed it for that particular combo, etc
- bluebarbet 6mo ago
  Thought experiment. Three populations, A, B, and C, divided geographically along a line. Individuals from group A can breed successfully with those from B but not with those from C. Individuals from group C can breed successfully with those from B but not A. How many species are there? This is why the term "species" can never be entirely objective. I remember the eureka moment I had when I finally understood this (admittedly somewhat simple) point.
  - naasking 6mo ago
    It can even be more subtle, it's entirely possible that some rare members of A can C breed, and some members of C and B would not be able to breed. The "fertility" relation can only be decided between two individuals, not groups. Group-level fertility is a statistical average of individual fertility. That said, I don't think that means that "species" is entirely subjective or meaningless.
  - lukan 6mo ago
    Is that based on a real example or hypothetical?
    - usrnm 6mo ago
      https://en.wikipedia.org/wiki/Ring_species https://en.wikipedia.org/wiki/Ring_species
  - afpx 6mo ago
    Even within one species, not every individual can successfully breed with every other.
- jayGlow 6mo ago
  if I'm not mistaken some human populations have neanderthal DNA which indicates that humans had reproduced with them and created fertile offspring. outside of that example there are a ton of species that can produce viable offspring like dogs, wolves and coyotes.
stainablesteel 6mo ago
my understanding of what classifies something as being a part of the same species is the fact that they can make children that are viable to have children themselves horses and donkeys can breed to make mules, but the mules usually cant reproduce, this is the same with tigons and ligers but sometimes the females are viable so if they can produce children that can produce children, they're the same species. where this line is blurred, so is the species line. geographical barriers have nothing to do with it.
- Vaphell 6mo ago
  > my understanding of what classifies something as being a part of the same species is the fact that they can make children that are viable to have children themselves things are a bit more complicated than that, because having fertile offspring is not a transitive property. Ring species: population A can mate with B, B with C, C with D, and D with E, but A and E cannot mate, even though they are part of the same continuous chain. Ensatina eschscholtzii salamanders in California exhibit this non-transitive behavior. Populations at the ends of the coastal ranges can interbreed with their neighboring populations, but where they meet in the south, the "ends" of the ring do not interbreed.
- rolph 6mo ago
  if you consider that geographic barrier is an environment of immediate lethality, or infecundity, that is physiological incompatability, and would be a speciation. if you consider that geographic barrier, simply precludes, interaction between individuals, then you will have founder effect, thus one population will be genetically decended from a sample of the larger population. https://en.wikipedia.org/wiki/Founder_effect https://en.wikipedia.org/wiki/Founder_effect
matt-attack 6mo ago
Seems to me, that we divide other animals based on some of the most minor of phenotypic expressions. The slight coloration of a bird’s crest, shape of some lizard’s nose. Yet with Homo sapiens we seem to be allergic to the idea that our drastic swings in physical attributes could possibly qualify as a different species (we obviously call them “races”). But they plainly diverged from each other due to geographic and reproductive isolation and adaptation to environments. Which is precisely what causes species to diverge into new ones. Are we supposed to pretend that Africans DONT have black skin due an adaptation to their environment? Do other animals get divided into races? I know dogs have “breeds” and we don’t consider those species. But I don’t hear about “races” in other animals.
- pegasus 6mo ago
  > Seems to me, that we divide other animals based on some of the most minor of phenotypic expressions It might seem like that to you, but you'd be wrong. Taxonomy prioritizes genetic distance and reproductive isolation over superficial visual traits that humans happen to find striking. While phenotypic variations like skin color or facial structure are highly visible, they represent a microscopic fraction of the overall genome and do not indicate the deep divergence required to define a new species. And from a genetic standpoint, Homo sapiens is remarkably homogeneous. Two humans from opposite sides of the planet are generally more genetically similar to each other than two chimpanzees from the same patch of forest. Traits like skin color (an adaptation for UV protection) or nose shape (an adaptation for humidity/temperature) are rapid evolutionary adjustments. They change quickly on an evolutionary timescale without requiring a fundamental split in the species' lineage. In contrast to other animals, because humans never stopped breeding with one another, we never had the chance to "drift" far enough apart to become different species. Geographic distance in humans has historically acted as a filter, not a wall. So there's your answer. Because of this unique genetic homogeneity (and not because of some imagined woke censorship), speaking of human subspecies would be scientifically mistaken.
  - like_any_other 6mo ago
    > Taxonomy prioritizes genetic distance [..] Two humans from opposite sides of the planet are generally more genetically similar to each other than two chimpanzees from the same patch of forest. Do you have a source? I've tried looking in the past, but couldn't find good "genetic distance" metrics that could be compared between humans and other species.
pegasus 6mo ago
> The definition of what constitutes a species is a human construct That makes it sound like the boundaries between species are arbitrary, but they are not. Sure, there are corner cases where things become debatable, but those are the rare exceptions, not the rule. > Two bird populations living in the same locale but divided by a mountain range therefore not naturally breeding with each other would classify as a different species, even if they could breed with each other. This is only the case if the separation has been there long enough for the two groups to develop distinct genetic markers or physical traits (like the beak shape or plumage mentioned in the original comment). The deeper reason they are classified as different species it that they are de-facto on different evolutionary trajectories. Which doesn't happen for human populations because historically, whatever obstacle divide us, we find a way to get around it.
rolph 6mo ago
"The definition of what constitutes a species is a human construct." speciation is reproductive incompatability. geographic isolation is more like founder effect than speciation.
- matt-attack 6mo ago
  That sounds like bunk. Has someone really tried to get every suspiciously similar but distinct species to mate? If I go and get these two to mate are they really going to delete one of the species: https://en.wikipedia.org/wiki/Altamira_oriole https://en.wikipedia.org/wiki/Altamira_oriole https://en.wikipedia.org/wiki/Baltimore_oriole https://en.wikipedia.org/wiki/Baltimore_oriole Just Think it logically there are millions and millions of animal species alone. The number of combinations is astronomical. Did someone really try out each combination? It’s silly. Of course not.
  - rolph 6mo ago
    perhaps you could explain why there is more than one type of organism on this planet.
- glerk 6mo ago
  > speciation is reproductive incompatability This is not necessarily true, even under a very strict definition of reproductive compatibility (offspring is itself not sterile, which excludes mules or ligers). For example, feral dogs, wolves and coyotes regularly mate and produce 100% viable offspring. You could argue that these are not really different species, but they are usually classified as such.
  - rolph 6mo ago
    "For example, feral dogs, wolves and coyotes regularly mate and produce 100% viable offspring" citation required. "You could argue that these are not really different species, but they are usually classified as such." you could argue, but i not, me. reproductive compatability means wild type organisms not artificially coerced. there are tiers of incompatability, biochemical, physiological, anatomical, behavioral, geophysical, geographical. incompatability on any of those levels, drives speciation. once again speciation is not about artificial [anthropogenic] induction of reproductive function, it is about wild type incompatability. no you cant argue. but your forgiven for not having the knowledge, and being fed half knowledge out of brevity. evolution is real, speciation is real, saying let it be so, and it will manifest itself, is not real. oh by the way, we are a species of primate, not dust, and rib bones.

by greazy 6mo ago

nelox 6mo ago

I’ve often dreamt of breeding with that mythical bird far, far away.

greazy 6mo ago
If you do cross the barrier, you could successfully mate with that mythical bird!

deleted 6mo ago

[deleted]

John7878781 6mo ago

> Two bird populations living in the same locale but divided by a mountain range therefore not naturally breeding with each other would classify as a different species, even if they could breed with each other. Really? I thought the requirements for species classification were: (1) must be able to reproduce and (2) offspring must be fertile. Is it less objective than that?

Archelaos 6mo ago
Polar bears can have furtile offspring with grizzly/brown bears. See: https://en.wikipedia.org/wiki/Grizzly%E2%80%93polar_bear_hybrid https://en.wikipedia.org/wiki/Grizzly%E2%80%93polar_bear_hyb...
- rolph 6mo ago
  the reproductive incompatability, is based on physiological range. in general, there are multi organizational levels of reproductive incompatability. in this case, the geographic distance, orogenic blockade, and ecological confounds of arctic conditions preclude easy mingling of U.arctos x U. maritimus.
whycombinetor 6mo ago
Interfertility is not an equivalence relation, does not form equivalence classes https://en.wikipedia.org/wiki/Ring_species https://en.wikipedia.org/wiki/Ring_species
rcxdude 6mo ago
There are a lot of subtleties. Ring species are a particularly fun one: you can have a population that live around some natural obstacle (like a large body of water) where individuals can breed successfully with individuals near to them but not with ones further way (like directly across the barrier), in a continuum of variation.
- lemonberry 6mo ago
  "Ring species are a particularly fun one" This is really interesting, thank you. I've never heard of "ring species" before.
joshuahedlund 6mo ago
Sometimes it’s hard to objectively tell whether two animals don’t appear to reproduce because they are unable genetically, or technically able still but behaviorally unwilling in normal natural circumstances, or we don’t know but we just haven’t observed it for that particular combo, etc
bluebarbet 6mo ago
Thought experiment. Three populations, A, B, and C, divided geographically along a line. Individuals from group A can breed successfully with those from B but not with those from C. Individuals from group C can breed successfully with those from B but not A. How many species are there? This is why the term "species" can never be entirely objective. I remember the eureka moment I had when I finally understood this (admittedly somewhat simple) point.
- naasking 6mo ago
  It can even be more subtle, it's entirely possible that some rare members of A can C breed, and some members of C and B would not be able to breed. The "fertility" relation can only be decided between two individuals, not groups. Group-level fertility is a statistical average of individual fertility. That said, I don't think that means that "species" is entirely subjective or meaningless.
- lukan 6mo ago
  Is that based on a real example or hypothetical?
  - usrnm 6mo ago
    https://en.wikipedia.org/wiki/Ring_species https://en.wikipedia.org/wiki/Ring_species
- afpx 6mo ago
  Even within one species, not every individual can successfully breed with every other.
jayGlow 6mo ago
if I'm not mistaken some human populations have neanderthal DNA which indicates that humans had reproduced with them and created fertile offspring. outside of that example there are a ton of species that can produce viable offspring like dogs, wolves and coyotes.

stainablesteel 6mo ago

my understanding of what classifies something as being a part of the same species is the fact that they can make children that are viable to have children themselves horses and donkeys can breed to make mules, but the mules usually cant reproduce, this is the same with tigons and ligers but sometimes the females are viable so if they can produce children that can produce children, they're the same species. where this line is blurred, so is the species line. geographical barriers have nothing to do with it.

Vaphell 6mo ago
> my understanding of what classifies something as being a part of the same species is the fact that they can make children that are viable to have children themselves things are a bit more complicated than that, because having fertile offspring is not a transitive property. Ring species: population A can mate with B, B with C, C with D, and D with E, but A and E cannot mate, even though they are part of the same continuous chain. Ensatina eschscholtzii salamanders in California exhibit this non-transitive behavior. Populations at the ends of the coastal ranges can interbreed with their neighboring populations, but where they meet in the south, the "ends" of the ring do not interbreed.
rolph 6mo ago
if you consider that geographic barrier is an environment of immediate lethality, or infecundity, that is physiological incompatability, and would be a speciation. if you consider that geographic barrier, simply precludes, interaction between individuals, then you will have founder effect, thus one population will be genetically decended from a sample of the larger population. https://en.wikipedia.org/wiki/Founder_effect https://en.wikipedia.org/wiki/Founder_effect

matt-attack 6mo ago

Seems to me, that we divide other animals based on some of the most minor of phenotypic expressions. The slight coloration of a bird’s crest, shape of some lizard’s nose. Yet with Homo sapiens we seem to be allergic to the idea that our drastic swings in physical attributes could possibly qualify as a different species (we obviously call them “races”). But they plainly diverged from each other due to geographic and reproductive isolation and adaptation to environments. Which is precisely what causes species to diverge into new ones. Are we supposed to pretend that Africans DONT have black skin due an adaptation to their environment? Do other animals get divided into races? I know dogs have “breeds” and we don’t consider those species. But I don’t hear about “races” in other animals.

pegasus 6mo ago
> Seems to me, that we divide other animals based on some of the most minor of phenotypic expressions It might seem like that to you, but you'd be wrong. Taxonomy prioritizes genetic distance and reproductive isolation over superficial visual traits that humans happen to find striking. While phenotypic variations like skin color or facial structure are highly visible, they represent a microscopic fraction of the overall genome and do not indicate the deep divergence required to define a new species. And from a genetic standpoint, Homo sapiens is remarkably homogeneous. Two humans from opposite sides of the planet are generally more genetically similar to each other than two chimpanzees from the same patch of forest. Traits like skin color (an adaptation for UV protection) or nose shape (an adaptation for humidity/temperature) are rapid evolutionary adjustments. They change quickly on an evolutionary timescale without requiring a fundamental split in the species' lineage. In contrast to other animals, because humans never stopped breeding with one another, we never had the chance to "drift" far enough apart to become different species. Geographic distance in humans has historically acted as a filter, not a wall. So there's your answer. Because of this unique genetic homogeneity (and not because of some imagined woke censorship), speaking of human subspecies would be scientifically mistaken.
- like_any_other 6mo ago
  > Taxonomy prioritizes genetic distance [..] Two humans from opposite sides of the planet are generally more genetically similar to each other than two chimpanzees from the same patch of forest. Do you have a source? I've tried looking in the past, but couldn't find good "genetic distance" metrics that could be compared between humans and other species.

pegasus 6mo ago

> The definition of what constitutes a species is a human construct That makes it sound like the boundaries between species are arbitrary, but they are not. Sure, there are corner cases where things become debatable, but those are the rare exceptions, not the rule. > Two bird populations living in the same locale but divided by a mountain range therefore not naturally breeding with each other would classify as a different species, even if they could breed with each other. This is only the case if the separation has been there long enough for the two groups to develop distinct genetic markers or physical traits (like the beak shape or plumage mentioned in the original comment). The deeper reason they are classified as different species it that they are de-facto on different evolutionary trajectories. Which doesn't happen for human populations because historically, whatever obstacle divide us, we find a way to get around it.

rolph 6mo ago

"The definition of what constitutes a species is a human construct." speciation is reproductive incompatability. geographic isolation is more like founder effect than speciation.

matt-attack 6mo ago
That sounds like bunk. Has someone really tried to get every suspiciously similar but distinct species to mate? If I go and get these two to mate are they really going to delete one of the species: https://en.wikipedia.org/wiki/Altamira_oriole https://en.wikipedia.org/wiki/Altamira_oriole https://en.wikipedia.org/wiki/Baltimore_oriole https://en.wikipedia.org/wiki/Baltimore_oriole Just Think it logically there are millions and millions of animal species alone. The number of combinations is astronomical. Did someone really try out each combination? It’s silly. Of course not.
- rolph 6mo ago
  perhaps you could explain why there is more than one type of organism on this planet.
glerk 6mo ago
> speciation is reproductive incompatability This is not necessarily true, even under a very strict definition of reproductive compatibility (offspring is itself not sterile, which excludes mules or ligers). For example, feral dogs, wolves and coyotes regularly mate and produce 100% viable offspring. You could argue that these are not really different species, but they are usually classified as such.
- rolph 6mo ago
  "For example, feral dogs, wolves and coyotes regularly mate and produce 100% viable offspring" citation required. "You could argue that these are not really different species, but they are usually classified as such." you could argue, but i not, me. reproductive compatability means wild type organisms not artificially coerced. there are tiers of incompatability, biochemical, physiological, anatomical, behavioral, geophysical, geographical. incompatability on any of those levels, drives speciation. once again speciation is not about artificial [anthropogenic] induction of reproductive function, it is about wild type incompatability. no you cant argue. but your forgiven for not having the knowledge, and being fed half knowledge out of brevity. evolution is real, speciation is real, saying let it be so, and it will manifest itself, is not real. oh by the way, we are a species of primate, not dust, and rib bones.