[Taxacom] [taxacom] Fw: Re: Phylogenetic classification?
Stephen Thorpe
s.thorpe at auckland.ac.nz
Sat Aug 1 21:58:22 CDT 2009
Hi Michael,
> Why aren't species relevant to a discussion of speciation mechanisms?!
> The species are putatively monophyletic groups
* No, this goes back to the previous taxacom discussion on
"paraphyletic species" - I think it is a confusion to apply
monophyletic/paraphyletic concepts to species, only GROUPS OF SPECIES.
* The fact that particular species may have insular distributions is
irrelevant to the discussion of speciation, because it is too easily
explained by other factors. For example, the fact that the giant
flightless weevil Anagotus turbotti has an insular distribution
(today) is easily explained by extinction on the mainland - it is
hardly a coincidence that the only giant flightless weevils surviving
in N.Z. today are either (1) on rat-free offshore islands, or (2) in
the middle of speargrass clumps on the mainland, which no sensible rat
would attempt to go near! A. turbotti is almost identical to A.
stephenensis, today confined to Stephens Island, but with subfossil
remains known from the mainland.
* Some island endemics certainly didn't have a formerly more
widespread distribution, as there is no reason why they should have
become extinct on the mainland - they are genuine (single island
group) primary endemics, probably evolved from a small founder
population of a mainland sister species. Example, the small flightless
stag beetle, Paralissotes triregius, on the Three Kings. There is an
almost identical species surviving in Te Paki, and other close
relatives elsewhere in Northland. A published record of a new species
of Paralissotes on the Poor Knights, allegedly closest to P.
triregius, has been shown to be bogus. It is P. mangonuiensis, which
also occurs on the Northland mainland, and without a phylogenetic
analysis, it was a purely subjective call that it is closest to P.
triregius.
* Anyway, I'm not sure where this discussion is going! It started from
someone's comment about "paraphyletic species". I said that paraphyly
is probably wrongly applied to species, and suggested that speciation
may well normally happen by way of rapid evolution of small
populations that become isolated by vicariant or dispersal events. I
gave an example of the Three Kings Islands, suggesting that many of
its endemics are clearly derived from mainland forms. OK, so that
DETAIL could be wrong if either (1) the whole northeastern island arc
was a continuous (or semicontinuous) landmass at some stage; or (2)
due to "island hopping", there are insular monophyletic species
groups, so Three Kings taxa could be closer to Poor Knights taxa, than
to mainland taxa. Nevertheless, both possibilities are consistent with
my point about "paraphyletic species". I assume you are not suggesting
that a monophyletic group could somehow evolve "in concert" on
unconnected islands, without gene flow between the islands!!!
Stephen
Quoting Michael Heads <michael.heads at yahoo.com>:
> Hi Steve,
>
> Why aren't species relevant to a discussion of speciation
> mechanisms?! The species are putatively monophyletic groups -
> they're the specimens you've put into one pile. Taxonomists don't
> usually think their species are simply the result of unrelated but
> convergent populations. For lots of intraspecific phylogenies see,
> e.g., any issue of Mol. Ecol.
>
> I can't think of any higher level insect taxa endemic to
> the north-east islands - you're the beetle man! I've relied on
> distributions of single species in this area simply because
> there are very few inter-specific phylogenies available. (There are
> countless papers describing new species, but many are single island
> endemics that don't tell you anything about biogeographic
> relationships). You could also have a look at landsnails:
> Delouagapia from Three Kings may be closest to Solomons taxa, not
> mainland NZ ones, Delos striata of Three Kings may be closest to
> Vanuatu ones, not the mainland NZ ones (which are closer
> to Tasmanian taxa).
>
> The usual story is that all the taxa endemic to the fringing
> offshore islands were formerly on the mainland but went extinct
> there. This doesn't explain the widespread mainland endemics
> that aren't on the offshore islands (but may have sisters endemic
> there).
>
> Michael
>
>
> Wellington, New Zealand.
>
> My papers on biogeography are at: http://tiny.cc/RiUE0
>
> --- On Sun, 8/2/09, Stephen Thorpe <s.thorpe at auckland.ac.nz> wrote:
>
>
> From: Stephen Thorpe <s.thorpe at auckland.ac.nz>
> Subject: Re: [Taxacom] Fw: Re: Phylogenetic classification?
> To: taxacom at mailman.nhm.ku.edu
> Date: Sunday, August 2, 2009, 12:04 PM
>
>
> Well, Michael, I haven't time to trawl through your publications
> looking for examples, so could you please cite some examples of
> putatively monophyletic groups endemic to the northeastern North
> Island arc of offshore islands (Three Kings down to say the Aldermans,
> or something)? Preferably, invertebrates, rather than plants. If you
> are correct, there ought to be examples of both. I note that there are
> several SPECIES with distributions like this, but that is hardly
> relevant to a discussion on speciation mechanisms. Examples of such
> species include the plant Meryta sinclairi (Three Kings, Poor Knights,
> Hen), and the giant weevil Anagotus turbotti (Three Kings, Poor
> Knights, Chickens). I also note two more possible explanations for
> such patterns:
> (1) dispersal by seabirds, which seem to prefer to breed on small
> islands (even in pre-rat times?). This can account both for plant
> distributions (through seed dispersal via birds), and invertebrates
> which live in bird nests and could be transported on the body of a bird;
> (2) the insular invertebrate faunas of New Zealand are in general
> better known than the mainland fauna - everybody wants to go there on
> field trips, and higher population densities on confined islands make
> finding species easier. Hence there is a greater chance of mainland
> sister species being overlooked.
>
> Stephen
>
>
> Quoting Michael Heads <michael.heads at yahoo.com>:
>
>>
>>
>>
>> From: Michael Heads <michael.heads at yahoo.com>
>> Subject: Re: [Taxacom] Phylogenetic classification?
>> To: "Stephen Thorpe" <s.thorpe at auckland.ac.nz>
>> Date: Saturday, August 1, 2009, 10:24 PM
>>
>>
>>
>>
>>
>>
>>
>> Dear Steve,
>>
>> Explanation 1 doesn't account for the offshore island group being a
>> monophyletic clade. Explanations 2 and 3 don't work for the general
>> case where there is a sister taxon on the mainland.
>>
>> Other possible explanations include faulty taxonomy in every example
>> (!), chance dispersal in the eye of storms ('given enough time even
>> the most unlikely events become inevitable') etc. But these are
>> all ad hoc arguments to explain away what is a normal type of
>> 'fringing island' pattern seen in many countries, e.g. the ABC
>> islands, Margarita etc. off northern Venezuela; the Moluccas,
>> Geelvink Bay islands, and the Bismarcks off northern New Guinea;
>> Mentawei islands off southern Sumatra; Japan - Taiwan etc. These all
>> correlate very nicely with major fault zones.
>>
>> Michael
>>
>> Wellington, New Zealand.
>>
>> My papers on biogeography are at: http://tiny.cc/RiUE0
>>
>> --- On Sat, 8/1/09, Stephen Thorpe <s.thorpe at auckland.ac.nz> wrote:
>>
>>
>> From: Stephen Thorpe <s.thorpe at auckland.ac.nz>
>> Subject: Re: [Taxacom] Phylogenetic classification?
>> To: taxacom at mailman.nhm.ku.edu
>> Date: Saturday, August 1, 2009, 9:51 PM
>>
>>
>> Dear Michael and World,
>>
>> Firstly, I was being neutral between vicariance and dispersal
>> theories. If we take the Three Kings as an example again, the small
>> populations that became isolated and evolved into new species may have
>> got there either by vicariance or dispersal.
>>
>> Secondly, it is not at all clear that Three Kings endemics are "often
>> closer phylogenetically" to those on other eastern islands like the
>> Poor Knights. Three factors which may contribute to the illusion of
>> this are:
>> (1) convergent evolution to similar insular environments
>> (2) extinction from the mainland (due to rats, forest clearance, etc.)
>> (3) translocation between islands by Maori (eg. the Meryta
>> sinclairi example)
>>
>> Stephen
>>
>>
>> Quoting Michael Heads <michael.heads at yahoo.com>:
>>
>>> Dear Steve et al.,
>>>
>>> This is what you'd expect based on Mayr's (1942) ideas that we were
>>> all brought up with. But after looking very hard for many decades,
>>> the geneticists now say there is little evidence for founder effect
>>> speciation. As for biogeography, the patterns in the New Guinea
>>> offshore islands that Mayr based his ideas on can be explained more
>>> efficiently by tectonic (strike slip) movements than by chance
>>> dispersal (see my New Guinea papers in J. Biogeogr. 2001 and 2002).
>>>
>>> The Three Kings endemics are often closest phylogenetically not to
>>> the mainland species that are closest geographically, but to
>>> sisters on offshore islands much further south (Poor Knights, Hen &
>>> Chickens, Chathams). The arrangement thus involves two parallel
>>> arcs, a mainland one and an offshore fringing islands one, and it
>>> seems very unlikely that e.g. the Poor Knights species dispersed to
>>> the Three Kings. This suggests that the outer arc may have been
>>> accreted to the inner one. See my New Caledonia paper (J. Biogeogr.
>>> 35: 2153. 2008) for notes on the Loyalties - Three Kings Ridge
>>> (probably a Cretaceous structure) and its accretion to New
>>> Caledonia/New Zealand from an origin further out to sea.
>>>
>>> Michael Heads
>>>
>>> Wellington, New Zealand.
>>>
>>> My papers on biogeography are at: http://tiny.cc/RiUE0
>>>
>>> --- On Sat, 8/1/09, Stephen Thorpe <s.thorpe at auckland.ac.nz> wrote:
>>>
>>>
>>> From: Stephen Thorpe <s.thorpe at auckland.ac.nz>
>>> Subject: Re: [Taxacom] Phylogenetic classification?
>>> To: taxacom at mailman.nhm.ku.edu
>>> Date: Saturday, August 1, 2009, 7:53 PM
>>>
>>>
>>> To expand a little on my former comment about paraphyletic species:
>>> Probably the concepts of 'monophyly', 'paraphyly', etc. are wrongly
>>> applied to species. GROUPS OF SPECIES are monophyletic or
>>> paraphyletic, not the species themselves. When we talk about
>>> decendants being included, we don't mean individuals decended from
>>> other individuals by parent-offspring relationships, we mean species
>>> decended from other species by speciation events. Even if we do
>>> somehow apply the concepts to species, there is no reason to "dislike"
>>> paraphyletic species in the same (Hennigian) way as for paraphyletic
>>> groups. For all we know, and I am convinced that this is true,
>>> probably most if not all cases of speciation renders a "parent
>>> species" "paraphyletic" in the sense we are talking about. I see
>>> abundant evidence for founder effect speciation! Just compare, say,
>>> the fauna of the Three Kings Islands with that of the adjacent New
>>> Zealand mainland. A small population of a widely distributed species
>>> becomes isolated on the islands, and evolves quickly (being a small
>>> population) into a distinct new species, while the mainland ones
>>> remain largely unchanged...
>>>
>>> Stephen
>>>
>>> Quoting Michael Heads <michael.heads at yahoo.com>:
>>>
>>>> Dear Ken et al.,
>>>>
>>>> In their book 'Speciation' (2004: 401) Coyne & Orr concluded that
>>>> ‘there is
>>>> little evidence for founder effect speciation’. Note that
>>>> these authors are not rabid
>>>> cladists or wacky vicariance biogeographers but
>>>> eminently respectable population
>>>> geneticists who can be taken seriously.
>>>>
>>>> Michael Heads
>>>>
>>>> Wellington, New Zealand.
>>>>
>>>> My papers on biogeography are at: http://tiny.cc/RiUE0
>>>>
>>>> --- On Sat, 8/1/09, Kenneth Kinman <kennethkinman at webtv.net> wrote:
>>>>
>>>>
>>>> From: Kenneth Kinman <kennethkinman at webtv.net>
>>>> Subject: [Taxacom] Phylogenetic classification?
>>>> To: taxacom at mailman.nhm.ku.edu
>>>> Date: Saturday, August 1, 2009, 2:45 PM
>>>>
>>>>
>>>>
>>>> Hi Richard,
>>>> Such an expectation by some cladists that
>>>> ancestor-daughter species "inexorably" become sister species seems to be
>>>> largely wishful thinking. This might tend to occur in cases where the
>>>> daughter species has a population that is not greatly smaller than the
>>>> population of the mother species. However, such an expectation seems
>>>> rather unlikely in frequent speciation where there some element of
>>>> "founder effect", especially when the mother species is highly
>>>> polytypic. This would be most evident in extreme cases where the founder
>>>> is a single pregnant female (such as for metazoans) or even a single
>>>> seed (for plants) which manages to survive in a new environment and is
>>>> reproductively isolated.
>>>> The paraphyly is even more evident when one adds the time
>>>> dimension and considers the earlier history of the mother species (which
>>>> would usually be broader both genetically and phenotypically) than it
>>>> was at the later time when it gave rise to its daughter species. If I
>>>> was a strict cladist, I would find it VERY disturbing to conceive of one
>>>> sister species having perhaps evolved a considerable period earlier than
>>>> its sister species. Given the lack or sparsity of a fossil record
>>>> (along the stem between nodes) leading to most such species pairs,
>>>> having no good evidence of relative age makes it even more problematic.
>>>> Extinction and a poor fossil record is truly a double-edged sword
>>>> that can make the recognition of clades both useful in the face of that
>>>> lack of information, but often only temporarily useful and subject to
>>>> destablizing challenges to that cladistic recognition when fossil
>>>> intermediates are eventually discovered. The trick is to occasionally
>>>> use paraphyly where cladistic assumptions seem likely to be overturned
>>>> by new information (fossil or otherwise). Paraphyletic speciation (and
>>>> paraphyly at higher taxonomic levels) is too common for strict cladism
>>>> to continue hoping that it won't cause them any major problems (and
>>>> classificatory unstability for us all). Stability and usefulness
>>>> require the occasional use of paraphyletic taxa at appropriate points in
>>>> the Tree of Life.
>>>> ---------Ken Kinman
>>>>
>>>> ----------------------------------------------
>>>> Richard Zander wrote:
>>>> As far as I can figure it out,
>>>> phylogeneticists expect a species that is paraphyletic (many exemplars
>>>> with a different species coming out of the middle of the lineage of
>>>> exemplars) to eventually become a sister group (reciprocally
>>>> monophyletic is the phrase). Therefore, a paraphyletic species should be
>>>> considered different from the autophyletic species because it will
>>>> inexorably become a sister group to it as exemplars get their act
>>>> together and homogenize their molecular data through recombination and
>>>> gene conversion and whatnot.
>>>>
>>>>
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>>>>
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