[Taxacom] It is possible to describe a new species?
hin175 at free.fr
Fri Dec 30 22:19:10 CST 2016
in addition, Antonio said that the genetic loci were maybe not well adapted.
Morphological differences can be due to plasticity or natural random variation around the mean value in different populations. Moreover, if they are pines surrounded by rain forest, I would suppose they are kind of "remnant' patches, thus probably experiencing a lot of genetic drift or ecological selection (both _can_ lead to speciation).
Talking about pines, their evolutionary (and speciation) rate seems to be very low, meaning (among other) that populations geographically or temporally isolated since a long time will still be able to hybridize.
Without knowing the data, and because (as you said) Pines are well-studied, I think (in my humble opinion) you should get more robust data before describing it as a new species :
- find loci (several, from chloroplast, nucleus and mitochondria) that discriminate each species (taking in account the coalescence theory, including Incomplete Lineage Sorting) to show clearly that there is some genetic split between the two populations (Ideally, population genetics methods could give you more informative data, i.e. using microsatellites or anonymous loci) and that this difference is similar to what is found in other pairs of species in pines (or at least conifers). You can find a lot of markers already used in pines, maybe even on your species...
- 22 years of phenology records is nice, but how the climate varied during this time (and also on longer period) in the area ? Was the phenology somehow sensitive to the climate variation ? Were some years so different that the phenology moved for one or the two species ? If the phenology is the key for the speciation of these populations, you need extensive data and explanation
- How the morphological differences are distributed in the two populations ? do you have a gap between the too populations, or is there some overlap? Did you observed some "mixed" or weird individuals (phenology A but morphology B) ?
- Why these two populations were consider as one species before ? What did you see that other scientists missed ? As Richard highlighted, why competent taxonomist said it was one species ?
Of course, you have the data, and you were in the field, not us, but your study would be far more robust with answers to these questions.
I would be glad there is a new Pinus species on earth, but if it's just a new useless synonym, it will be.... useless.
Good luck, Damien
On 31/12/2016 05:31, Richard Pyle wrote:
> Hi Antonio,
>> On the other hand, the definition of
>> species is clear: If there are no crosses are different species. This is a
>> situation that exceeds my knowledge, my experience.
> Unfortunately, the definition of a species is not so clear. Even in the context of the biological species concept (which you refer to), it presumes there is an opportunity to cross before one can assert that they don't cross (and therefore should be considered distinct species). For example, in species that occur on islands (separated by physical space), there may be two populations on different islands that are very similar to each other (morphologically & genetically). Because of the spatial separation, they don't cross with each other, because they don't have opportunity to cross with each other. But just because they are physically unable to cross, doesn't mean we automatically consider them to be distinct species. Generally, they are considered distinct species only when there are consistent differences (morphological or genetic) between them. Such differences presumably accumulated over many generations without any crosses between them (via evolution), and therefore represent distinctions that biologists recognize through naming them as distinct species.
> The example you gave seems to be very analogous, except instead of spatial barriers to crossing, the barrier is temporal. Like the populations on separate islands, simply the existence of a (potential) barrier is generally not used to justify assigning distinct species names to each population. Instead, it's generally best to document morphological or genetic differences (as an indication of divergent evolution) between individuals of the two populations, and using those differences as the main justification for regarding them as distinct species.
> Since the time of Linnaeus (and further supported by Darwin and others), the de-facto definition for a species is that "a species is what a competent taxonomist or community of taxonomists says it is". In answer to your question about whether to describe a new tree species to recognize them as distinct, I think the question you need to answer is "Would the morphological differences between the two forms, absent any detectable genetic differences, be sufficient to treat them as distinct species if they were separated geographically, rather than by time of pollination?" Or, more generally, "Would labelling these two forms with distinct species names increase the effectiveness of communication among biologists, or would doing so add more confusion?"
> Neither of these questions has a "correct" answer.
> Richard L. Pyle, PhD
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