Well I guess this is another flaw of classification. Species is defined as “Species are groups of actually or potentially interbreeding populations that are reproductively isolated from other such groups” (Futuyma, 1998). The reproductive isolation can be genetic, or it can be simply geographical or habitual. There is no criteria that says two distinct species cannot interbreed, even though some species can and others cannot. For example dogs, wolves, and coyotes can all interbreed, but within the Felidae genus there are cat species that cannot interbreed.
What I was saying is that humans are the only living member of the Homo family. Homo sapiens exist as a single species because to some degree their is no limitation on our interbreeding. Sure there are many cultural norms and customs that have discouraged inter-racial, inter-class, inter-ethinicity breeding, but it has not stopped these things. I would argue (along with some evolutionary biologists) that the fact that homo sapiens exist in one giant gene pool is pretty unique among animals given the wide amount of territory that we populate.
The reproductive isolation can be genetic, or it can be simply geographical or habitual.
This is probably not relevant to our point, but Futuyma (2005) Evolution p356 defines reproductive isolation as “reduction or prevention of gene flow between populations by genetically determined differences between them”—i.e. it’s not enough that they are geographically separated.
homo sapiens exist in one giant gene pool
This just seems to be a claim that the population size of our species is quite large. There are other species of mammal with large populations. Again, the relevance of any of this to sex-determination is rather doubtful.
It should be pointed out here that biological genuses, families, orders, and so on do not exist. If you discover a new continent full of organisms not previously known, there is no observation you can make to decide whether two of their species are, or are not, members of the same genus. It would be a wrong question. Every classification above the species level exists solely for the convenience of biologists talking about the organisms they are studying. Even at the species level, where we can talk about interbreeding populations, multiple definitions are possible and edge cases exist (sometimes so large as to make the very idea of a tree of descent moot).
The higher-level classifications may (but do not always) correspond to subtrees of the evolutionary history, but their ranking into genuses, orders, subfamilies, and so on in the 40-odd different levels available in current taxonomical practice is a product of human convenience, nothing more.
So the statement that some genus includes only one species is not a statement of biology. It is a statement about biologists.
None of the things you mention are likely to affect the sex determination system.
The only what?
Well I guess this is another flaw of classification. Species is defined as “Species are groups of actually or potentially interbreeding populations that are reproductively isolated from other such groups” (Futuyma, 1998). The reproductive isolation can be genetic, or it can be simply geographical or habitual. There is no criteria that says two distinct species cannot interbreed, even though some species can and others cannot. For example dogs, wolves, and coyotes can all interbreed, but within the Felidae genus there are cat species that cannot interbreed.
What I was saying is that humans are the only living member of the Homo family. Homo sapiens exist as a single species because to some degree their is no limitation on our interbreeding. Sure there are many cultural norms and customs that have discouraged inter-racial, inter-class, inter-ethinicity breeding, but it has not stopped these things. I would argue (along with some evolutionary biologists) that the fact that homo sapiens exist in one giant gene pool is pretty unique among animals given the wide amount of territory that we populate.
So was the claim “Humans are the only single species mammal” simply a claim that humans are the only mammal with their own genus? That’s certainly not true, see http://en.wikipedia.org/wiki/Category:Monotypic_mammal_genera
This is probably not relevant to our point, but Futuyma (2005) Evolution p356 defines reproductive isolation as “reduction or prevention of gene flow between populations by genetically determined differences between them”—i.e. it’s not enough that they are geographically separated.
This just seems to be a claim that the population size of our species is quite large. There are other species of mammal with large populations. Again, the relevance of any of this to sex-determination is rather doubtful.
It should be pointed out here that biological genuses, families, orders, and so on do not exist. If you discover a new continent full of organisms not previously known, there is no observation you can make to decide whether two of their species are, or are not, members of the same genus. It would be a wrong question. Every classification above the species level exists solely for the convenience of biologists talking about the organisms they are studying. Even at the species level, where we can talk about interbreeding populations, multiple definitions are possible and edge cases exist (sometimes so large as to make the very idea of a tree of descent moot).
The higher-level classifications may (but do not always) correspond to subtrees of the evolutionary history, but their ranking into genuses, orders, subfamilies, and so on in the 40-odd different levels available in current taxonomical practice is a product of human convenience, nothing more.
So the statement that some genus includes only one species is not a statement of biology. It is a statement about biologists.
Yes, this is true of course.
And whoever mentions cladistics first wins the thread. Ready, set...