Cocos nucifera--only one species?

[Mandrew968]

During the last SFPS general meeting, we were fortunate to have Dr. Carl Lewis( co-author of Genrea Palmarum II) as our guest speaker. He took us on a slide show through the South Pacific--one of the highlights was his rediscovery of the palm known as Heterospathe glauca(the real one, not barfodii). After seeing his photos of the palm in habitat I was eager to ask him questions about the palm. One of the questions was in reference to the trunk and 'crownshaft', to which he replied, "I'm a taxonomist. All I care about is the floral aspects--I don't look at the rest of the palm..." This was a little shocking to me because I couldn't fathom just rediscovering a palm and not studying EVERY part of the plant...

Later on, while walking through the 'U' campus, I was looking up at the coconut palms and remembered what Dr. Lewis had mentioned. This thought brought me to a question I thought I might raise here on Palmtalk: If floral aspects of a palm are so instrumental in determining a species, then why is the spicata form of Cocos not its own species? I am very aware of all the different cultivars of coconut palms and as I understand it, taxonimists consider them all to be Cocos nucifera. However, the spicate inflorescence and infructescence of the spicata variety is very distinct and taxonomically worth noting, I think. Can anyone tell me why this form is not its own species if floral aspects hold so much taxonomical weight? Is this just something that taxonomists have not gotten to yet? Anyone else have anything to add? I didn't use the term 'red spicata' because there are also green forms with the spicate flower structure...

[Zeeth]

This is a very good question! It seems interesting and not unlikely that the spicate inflorescence is enough to give a different species (or at least subspecies). I suspect though that because the coconut is often considered domesticated, it's harder to make the split without looking at DNA.

[Mandrew968]

This is a very good question! It seems interesting and not unlikely that the spicate inflorescence is enough to give a different species (or at least subspecies). I suspect though that because the coconut is often considered domesticated, it's harder to make the split without looking at DNA.

Keith, first off, thank you for responding. As for your mention of DNA--taxonimists have made many species classifications without the use of DNA. I see no reason why they would need such a tool, now...

[Zeeth]

This is a very good question! It seems interesting and not unlikely that the spicate inflorescence is enough to give a different species (or at least subspecies). I suspect though that because the coconut is often considered domesticated, it's harder to make the split without looking at DNA.

Keith, first off, thank you for responding. As for your mention of DNA--taxonimists have made many species classifications without the use of DNA. I see no reason why they would need such a tool, now...

You are correct, but what I'm saying is that, if my understanding is correct, domesticated plants and animals can often have characteristics that would imply a much further separation taxonomically than is actually the case. As an example, I'm sure that if dogs were a wild species but existed as they currently do, the greyhound would probably be considered a different species (or at least subspecies) than a St. Bernard. Even here, dogs and wolves used to be considered different species, but DNA evidence didn't support this. Also, with plants I'd say it's probably more difficult, because interspecific and intergenic hybrids are much more common, so it might be harder to justify that spicata isn't separate solely because it hybridizes. That's why I think it'd take DNA to determine for sure how far spicata is from the rest of coconuts. If the trait occurs because of one base pair substitution, it's just a regular coconut, but it might be a huge difference that justifies a new species.

PS: now that I think about it, I'm not sure that the term subspecies is used with plants even though I keep saying it.

[Mandrew968]

I think I understand your point(dogs and wolves are not considered different species??? This is news to me--different latin names, right?)... as far as cultivation is concerned, I am not sure the spicate floral structure was bred into coconuts--never heard of that(but I don't know). I have heard coconut size, palm height and disease resistance have been reasons for genetic manipulation but I couldn't see a reason to breed for a spicate floral structure--this would ultimately mean smaller and less coconuts which is not good for a coconut business... it could very well be true that the spicata coconut was bred to be florally distinct, but for what reason I have no idea.

[doranakandawatta]

.... I am not good with identifying tropical palms.... IPS Director

Let's hope about Cocos nucifera spicata!

[Zeeth]

I think I understand your point(dogs and wolves are not considered different species??? This is news to me--different latin names, right?)... as far as cultivation is concerned, I am not sure the spicate floral structure was bred into coconuts--never heard of that(but I don't know). I have heard coconut size, palm height and disease resistance have been reasons for genetic manipulation but I couldn't see a reason to breed for a spicate floral structure--this would ultimately mean smaller and less coconuts which is not good for a coconut business... it could very well be true that the spicata coconut was bred to be florally distinct, but for what reason I have no idea.

Yup! There are currently 39 official subspecies of Canis lupus, one of which is Canis lupus familiaris (dog)!

As for the spicate structure, I have heard that it's a popular cultivar in some areas because the nuts can be knocked down more easily by throwing stuff at them, so you don't need to climb the palm to access the fruit.

[empireo22]

http://culturesheet.org/_media/photographs:plant_photography:arecaceae:cocos:treeheaded_cocos.jpg?cache=

tongatapu, Tonga

[Toby]

Nature can be extremely confusing and taxonomists have achieved a great deal to sort it and make it easier to understand for us, but they certainly have not figured out all of its workings. DNA is a tool, like plain observation and comparison of a plants reproductive organs so far, to better understand how different plants are related, nothing more, no magic involved. The reason taxonomists look at the flowers is because they are thought to be less prone to drastic changes through environmental factors (take human selection in dogs: despite thousands of years of efforts, they can all still multiply successfully). Domesticated plants like the coconut are particularly prone to developing sports like the "spicata" form. The rule is though, that in order to constitute a new species, a population of plants must have at least 3-4 clear and distinct differences to another population, and no intermediate forms, to be considered a separate species. I do disagree with Carl Lewis on the floral aspects. This is how taxonomists are trained, but there are plenty of other features of a plant that are imortant for differentiation, one just has to develop an eye for them, and amateurs often have more patience for this than the professionals.

Best, TOBY

[sarasota alex]

Andrew Henderson has a chapter titled "Species concept" in his taxonomic studies. Here it is from "The revision of Geonoma":

In this study the Phylogenetic Species Concept (PSC) is used. Under this concept, species are defined as: "the

smallest aggregation of populations.... diagnosable by a unique combination of character states in comparable

individuals" (Nixon & Wheeler 1990). Individual specimens are considered comparable because all are

fertile. The terms character and trait are used in the sense of the PSC. Characters are qualitative variables the

same states of which are found in all comparable individuals within a terminal lineage (i.e., species); traits are

qualitative variables with more than one state found within species (although some species may have only one

state of a given trait). The PSC is chosen here because it has an explicit definition, theoretical background and

discovery operation, as described below. This is discussed in more detail in Henderson (2005a; see also

Henderson 2004 and 2005b).

Two operational modifications are necessary in order to apply the PSC. According to Davis & Nixon

(1992), phylogenetic species are delimited by successive rounds of aggregation of local populations, based on

analysis of characters and traits. Because palm specimens are seldom collected on a population basis and

because there is no a priori method of placing specimens in populations and consequently distinguishing a

priori between characters and traits, all specimens (i.e., treating specimens as populations) and all qualitative

variables (i.e., traits and characters) were used in the analysis (see below).

A second modification of the PSC involves subspecific variation. Some groups of specimens with unique

combinations of qualitative character states (i.e., species) may vary internally in trait state distributions and

quantitative variables, and may occur in disjunct geographic areas. Based on these criteria subgroups may be

recognizable. Luckow (1995), in her discussion of the PSC, stated that “groups of populations that differ not

by fixed characters, but by differences in mean values, would be recognized as subspecies or varieties [under

the PSC].” A slightly modified version of this is followed here. If subgroups can be delimited by traits (i.e.,

with unique combinations of trait states) and/or by geographic disjunctions, and these subgroups are

supported by analysis of quantitative variables (see below), then a phylogenetic subspecies concept is applied.

In summary, the PSC is applied to groups of specimens with unique combinations of qualitative character

states, and a PSC subspecies concept is applied to subgroups that can be delimited by analysis of traits,

geography and quantitative variables.

Species delimited under the PSC are testable hypotheses (Wheeler & Platnick 2000). This testing depends

on distinguishing characters from traits, i.e., the test is that characters are not traits and traits are not

characters. In the first case, a supposed character may turn out to be distributed as a trait. Such a

misinterpretation would give an overestimation of the number of species. In the latter case, a supposed trait

may be distributed as a character, giving an underestimation of the number of species.

[sgvcns]

For me it is the idea of lumping or splitting.

Some taxonomists are happy for small variations to delineate species.

Others look at overall variation as a range of form in a species.

Historically we have many palm forms described as new species.

I don't think it helps that most taxonomists work off dried specimens and are not involved in field work.

Personally I favour lumping as a way forward.

Look at how many palms have entire leaf/clumping variations to see how easy it is to split forms off as species.

[empireo22]

Take Archontophoenix spp. there are many different species in that genus though they do not vary greatly.

Keith brings up a good point that most are just cultivars created by man.

I cant see why spicata should be its own species maybe someone can explain the difference in spicata?

[edric]

All that said, here is the link to the genus page, and it's three infraspecific taxa (var. or subspecies), Ed

http://www.palmpedia.net/wiki/Category:COCOS

[Mandrew968]

Nature can be extremely confusing and taxonomists have achieved a great deal to sort it and make it easier to understand for us, but they certainly have not figured out all of its workings. DNA is a tool, like plain observation and comparison of a plants reproductive organs so far, to better understand how different plants are related, nothing more, no magic involved. The reason taxonomists look at the flowers is because they are thought to be less prone to drastic changes through environmental factors (take human selection in dogs: despite thousands of years of efforts, they can all still multiply successfully). Domesticated plants like the coconut are particularly prone to developing sports like the "spicata" form. The rule is though, that in order to constitute a new species, a population of plants must have at least 3-4 clear and distinct differences to another population, and no intermediate forms, to be considered a separate species. I do disagree with Carl Lewis on the floral aspects. This is how taxonomists are trained, but there are plenty of other features of a plant that are imortant for differentiation, one just has to develop an eye for them, and amateurs often have more patience for this than the professionals.

Best, TOBY

Thank you for your knowledgable response and valued opinion. Cocos nucifera as a species is quite complex--all of the different varieties as well as the vast amount of time it has been cultivated clearly obfuscate its origins. I am not even sure if the debate as to whether the coconut palm is old world or new world, has been settled. I have heard the spicata form is not new world, but I am far from certain.

[Mandrew968]

Alex, what can I say... I read that twice--from ecology and evolution of palms right? I have the book--dense read.. Yes I understand there must be 3 distinct traits for a species to be recognized. But what constitutes a trait? Fruit size? Fruit shape? Petiole color? Floral structure? Overall palm height? These are just some of the differences I know coconuts to exhibit--can anyone think of any other noteworthy differences?

[Mantis sp.]

old but interesting! I thought the same. Cocos has been poorly studied.

[Alberto]

For me it is the idea of lumping or splitting.

Some taxonomists are happy for small variations to delineate species.

Others look at overall variation as a range of form in a species.

Historically we have many palm forms described as new species.

I don't think it helps that most taxonomists work off dried specimens and are not involved in field work.

Personally I favour lumping as a way forward.

Look at how many palms have entire leaf/clumping variations to see how easy it is to split forms off as species.

I disagree. Lumping species (or varieties or subspecies) to a single one will not help to preserve the diversity. Why protect a little specific "different" population of animal or plant that is well represented in other places???

[tank]

For me it is the idea of lumping or splitting.

Some taxonomists are happy for small variations to delineate species.

Others look at overall variation as a range of form in a species.

Historically we have many palm forms described as new species.

I don't think it helps that most taxonomists work off dried specimens and are not involved in field work.

Personally I favour lumping as a way forward.

Look at how many palms have entire leaf/clumping variations to see how easy it is to split forms off as species.

I disagree. Lumping species (or varieties or subspecies) to a single one will not help to preserve the diversity. Why protect a little specific "different" population of animal or plant that is well represented in other places???

I agree with Alberto.

In the case of "entire leaf/clumping variations" example these are more often than not genetically unstable and are never used split a species into a separate species or subspecies. Something like Sabal "Lisa" would just be considered a mutant or possibly a cultivar (but I assume that if you crossed two Sabal "Lisa's" you'd get some percentage of the offspring that would have a normal leaf) although someone might want to help me on what defines a cultivar as far as genetic stability goes....

Good Wiki article on defining species. Very easy read on a rather complicated topic.

http://en.wikipedia.org/wiki/Species_problem

[_Keith]

Inexpensive DNA testing is going to spoil all of the fun for taxonomists. No more arguments, no more changing names back and forth. It's enough to drive a scientist to drinking, I tell ya.