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Comment by daveslash | Hacker News Reader

I don't believe it. Very interesting read, and I don't doubt that the plants all originated from the same species . However, I'm not convinced that they are still the same species; can one assert that we have, through artificial selection, induced speciation? I believe this is more likely.

I will admit that the definition of "species" is subject to debate. The general definition to which I subscribe requires that two individuals are able to mate, produce offspring, and that can then mate and produce offspring of its own. A major shortcoming with this definition, however, is that it does not address Ring Species. http://en.wikipedia.org/wiki/Ring_species

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I'm not convinced that they are still the same species; can one assert that we have, through artificial selection, induced speciation?

One word: "dogs".

(Are you skeptical that chihuahuas and huskies are the same species? Some dog breeds are incapable of mating successfully without artificial insemination, or reproducing effectively -- think of a great dane foetus gestating in a female chihuahua -- but within a small single-digit number of generations they can produce hybridised "mutts" that are interfertile. Similarly, the brassicae are pretty much the same thing.)

It has been suggested that we consider dogs to be separate species. I completely agree with that, but without human intervention, wouldn't breeds that can't reproduce naturally (great dane & chihuahua) most likely lead to separate species given enough time? http://www.scientificamerican.com/article/an-immodest-propos...

I don't understand why you don't believe it. It's quite wide-spread knowledge, and a quick check doesn't show any signs that it's a wide-spread urban legend.

I noticed that your understanding of 'species' doesn't consider obligate parthenogenesis. There are, for example, some 50 species of lizard that only reproduce parthenogenetically. Under your definition, these are not a species because there is no mating. I submit that that is a much more critical shortcoming than a ring species.

Perhaps your objection is more based on a lack of knowledge than anything else?

I submit that you're probably correct about my lack of understanding. I'm really not sure what a species is, not scientifically - and some googling suggests there is debate in the scientific community. How would you define species?

I don't define species because I don't need to. As you found, it's an unresolved topic. For my daily life, the reproductive compatibility definition you mentioned is a reasonable approximation. (I usually think of it as having the additional proviso "or the parents are compatible", since some individuals are infertile.)

Quoting now from Stephen J. Gould (1992):

> I do not say that these criteria are free from exceptions; nature is nothing if not a domain of exceptions, where an example against any clean generality can always be found. Some distinct populations of plants, for example, can and frequently do interbreed with others that ought to be separate species by all other standards. (This is why the classification of certain groups--the rhododendrons, for example--is such a mess.) But the criteria work in the vast majority of cases, including humans.

Since then we've learned a lot more about bacteria, which employ horizontal gene transfer. This completely breaks the traditional model.

Our own human cells can also pull off some odd tricks. See http://en.wikipedia.org/wiki/HeLa#New_species_proposal for one proposal for why HeLa cells should be considered its own species. (Note also the mention of special rules for an independent unicellular asexually reproducing species.)

I don't think that it is really a 'debate'. There are different species concepts that are used depending on the needs of the situation (http://en.wikipedia.org/wiki/Species#Other_species_concepts). A single definition cannot be found for less divergent groups because speciation is really a continuous process. Also the mechanisms and course of the process differs between taxonomic groups and, in some cases, may never be 'complete'. The case of horizontal gene transfer mentioned below occurs in eukaryotes as well (http://en.wikipedia.org/wiki/Horizontal_gene_transfer#Eukary...).

Using your own definition for species, you're supporting the claim that they are all the same species. They have produced "offspring."

Can you cross pollinate cauliflower and broccoli (outside of genetic engineering)? I honestly cannot say with certainty, but I tend to doubt it. If you can, I would think same species; if you can't, I'd think separate. My supporting evidence is non-scientific and anecdotal - having a garden for 15 years with both plants in close proximity I would have thought if cross pollination had been possible it would have happened in that time frame.

Yes. http://en.wikipedia.org/wiki/Broccoflower

Google is your friend.

FWIW, an awful lot of seed growing involves preventing unwanted crosses, but unless you were saving seeds from your garden you might overlook this.

Thank you. From the wiki page, I can't tell if that's Broccoflower is the result of cross-pollination as would happen naturally or the result of direct human intervention - I also can't tell if the seeds from Broccoflower are viable - I'll Google around more and learn :-)

As for overlooking - you're right, I did and should have thought of that before commenting. After a few attempts at saving seeds it became obvious to me that buying them each season was preferable.

"I don't believe it." Most people here are talking about technicalities of the definition of species, etc.

But what I'll mention to you is: Have you not noticed how similar the taste is between some of these mentioned items?

Yes, they do taste similar, and I absolutely believe that they are all derived from the same species - but I'm not convinced that they are still the same species.

Biologists and botanists have a way to avoid any confusion. For them, they belong to the same genus, but not to the same species.

Good point, and I suppose they really are: http://www.dailymail.co.uk/femail/food/article-1244520/The-f...

The word 'believe' has no place in a scientific debate. Either you know or you don't know. What you believe does not enter into it, that means you need to do more research or read up on the research that has already been done.

That's nonsense. There are lots of parts of science where someone could reasonably say "I believe it's this, but I'll change my mind if future science changes my mind".

An example of where this is useful is around Neanderthals. "Did they have language?", "Did they have burial with ceremony?" are questions where it's fine to have belief on the current evidence because there's not enough data to know the answer.

This is incorrect. There are many scientific hypotheses that are widely believed to be true, such as P!=NP or global warming. To say that "we don't know", or "it's equally probable that..." would be extremely misleading. And you'd be hard pressed to find a scientist who doesn't believe in one outcome or the other.

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