[Taxacom] Oceanic dispersal vs. vicariance
Kenneth Kinman
kinman at hotmail.com
Sun Jun 17 21:24:12 CDT 2018
Hi Jason,
I agree. Your description "instead it all ends in a series of zingers written in scripted, telegraphic style" would pretty much describe my views of John's polemics in particular. Especially when his zingers involve creationists or Hitler Thus my reluctance to respond to most of his e-mails. I think I will now answer Michael's post instead.
------------------- Ken
________________________________
From: Taxacom <taxacom-bounces at mailman.nhm.ku.edu> on behalf of JF Mate <aphodiinaemate at gmail.com>
Sent: Sunday, June 17, 2018 8:41 PM
To: Taxacom
Subject: Re: [Taxacom] Oceanic dispersal vs. vicariance
John, Michael, this isn´t going anywhere. I was waiting for a hint of
proper debate but instead it all ends in a series of "zingers" written
in scripted, telegraphic style. I have not seen any ideas presented by
either one of you that aren´t encapsulated and operationalized in a
superior manner in cladistic biogeography or evolutionary
biogeography, sans the unproven axiomatic mania that dispersal doesn´t
occur. In fact, you don´t seem to to agree on a definition of
dispersal or if it even occurs (Michael says he doesn´t question
"slight" dispersal, but you say otherwise). To move the debate towards
some clear definition of dispersal, I would point to present day,
observable examples such as Inachis io crossing from Europe to NA or
Danaus plexippus going the other way. To me these are clear, working
examples of dispersal, some successful (D. plexippus) others, like
Inachis io, failing time after time. Neither is a slight jump Please
think about this carefully before replying.
In regards to the dung beetle fauna of Madagascar, we first have to
consider the fossil evidence. The oldest known Scarabaeinae fossil is
of unknown affinity (Prionocephale deplanate, U Cretaceous; Krell,
2007). Between this assumed Scarabaeinae fossil and clearly
identifiable ones we have to jump to the Palaeocene-Miocene, where we
find ichnofossils (brood balls). This in itself is interesting because
they are the sort of easily preserved structures we should expect to
commonly find (actually common in paleosols in SA), but we don´t in
older deposits, so we must assume that they were either uncommon or
nonexistent. This doesn´t mean that Scarabaeinae were not found then
but that lineages that build deep nests with brood balls evolved after
the K-T. These lineages are also found in Madagascar nowadays
(Helictopleurus, Onthophagus, Scarabaeus) so their presence there is
difficult to reconcile with a purely vicariant model, even without
considering the phylogenetic evidence which have them evolving in the
Palaeocene.
The Malagasy genera endemic genera (except Onthophagus) that have been
studied yield the following date estimates:
Arachnodes, Epilissus & Apterepilissus 79-49my
Nanos & Apotolamprus 24-15my (Wirta, Helena. (2018). Dung beetle
radiations in Madagascar. )
Epactoides 30-19my
Helictopleurus 37-23 (doi.org/10.1016/j.ympev.2008.03.010)
Scarabaeus 24-15my
Onthophagus: >3 colonizations (age of entire Onthophagini lineage, Palaeocene)
doi:10.3390/insects2020112
doi.org/10.1111/j.1096-0031.2006.00139.
The Aphodiiinae presents more complex biogeography. The oldest fossil
(a generalized "aegialid-like" genus from the Lower Cretaceous,
Cretaegialia) suggests a window that may enable some of the lineages
to be Gondwanan. However, the "coprophilous" Aphodiini are generally
assumed to be Laurasian in origin (incorrectly in my opinion but we
have to refer to the published studies). This in itself, plus their
assumed recent origin ( <60my; DOI: 10.1016/j.ympev.2003.10.019; the
oldest fossil evidence is Miocene.), makes it almost impossible for
the lineage to have been present in Madgascar before its split from
Gondwana.
At the level of the subgenera that exist in Madagascar, most of them
are shared with Africa, even down to species:
Nonendemic subgenera: Aganocrossus (1 nonendemic sp); Blackburneus (2
nonendemic sp); Koshantschikovius (4 endemic sp); Paradidactylia (1
endemic sp); Pleuraphodius (1 endemic sp, 1 nonendemic sp);
Pharaphodius (1 nonendemic sp, 2 endemic sp); Pseudopharaphodius (1
nonendemic sp); Labarrus (2 nonendemic sp; 1 tramp; 1 endemic sp);
Mesontoplatys (2 nonendemic sp); Neocalaphodius (1 nonendemic sp);
Nialaphodius (2 nonendemic sp).
Endemic Malagasy subgenera: Madagaphodius (1 sp); Neoemadiellus (8 sp).
Bordat, Paulian & Pittino 1990
The other Aphodiinae tribes have varying degrees of endemicity that
suggest vicariance for some (e.g. Saprosites, Aulonocneminae/i) or
dispersal for others (Rhyparini). I believe the above examples are
sufficient to illustrate the point.
Best
Jason
On 12 June 2018 at 23:09, Michael Heads <m.j.heads at gmail.com> wrote:
> Jason,
> You write: ''... it seems that we can all more or less agree that timing is
> the key difference between both mechanisms, and in that context patterns in
> themselves can´t distinguish either mechanism, so they are not informative
> in this specific instance and we can dispense with tracks
> and other such pattern searching'.
>
> Of course, you are free to ignore distributions if you like. But here is
> what the author of the most cited bbiogeographic work had to say:
>
> "To do science is to search for repeated patterns, not simply to accumulate
> facts, and to do the science of geographical ecology is to search for
> patterns of plant and animal life that can be put on a map". (MacArthur,
> 1972: 1).
>
> On Wed, Jun 13, 2018 at 8:21 AM, JF Mate <aphodiinaemate at gmail.com> wrote:
>>
>> Sorry to all for dropping off the map. In particular apologies to Ken
>> for leaving him steadfastly defending the fort on his own. Anyway, it
>> seems that we can all more or less agree that timing is the key
>> difference between both mechanisms, and in that context patterns in
>> themselves can´t distinguish either mechanism, so they are not
>> informative in this specific instance and we can dispense with tracks
>> and other such pattern searching.
>>
>> So when you claim that “... much of the opposition on timing comes
>> from rejection of tectonic correlations that are earlier than the
>> (minimum) molecular estimates.” you are mistaken. The problem is that
>> if the timing is not in agreement with the tectonic evidence then
>> vicariance can no longer be a contender for the time being. This is
>> not a rejection of vicariance but a simple observation that the
>> evidence available just isn´t´t in agreement and dispersal must be
>> considered as likely.
>>
>> Saying that “To me this is about as feeble as it gets with
>> biogeography - that dispersal occurred more than once but left no
>> evidence. But it happened more than once for sure.” is semantic
>> footplay posing as scientific rigour. There are limitations and these
>> have always been acknowledged by molecular taxonomists from the
>> beginning, but not to be used as an underhanded, semantic mallet to
>> clobber dissent. And therein lies the issue I have with you and
>> Michael. Nobody is questioning vicariance, you question dispersal. So
>> really, we only need one example of dispersal to invalidate your
>> epistemological building and that is pushing you to make semantics
>> your arena with such choice examples as “I do not complain about
>> molecular estimates of divergence, I only complain about minimums
>> being misrepresentated as actual or maximal. There is a difference!”
>> or “It only involves the Big Lie about molecular estimates.” Quacks
>> like a duck and all that.
>>
>> You also try to distract the argument by introducing other groups that
>> were not part of the initial discussion. Neither vicariance nor
>> dispersal are on trial here. They are both generally accepted
>> mechanisms (except by you two it seems) and the only question
>> originally posed was, which had a hand in the Platyrrhini, so let´s go
>> back to the Platyrrhini. The available evidence, the research on this
>> topic, is pretty much in agreement with Ken´s assertion. What do you
>> bring to the table to refute this. Claiming that “One can only assert
>> otherwise by the Große Lüge that fossil calibrated molecular estimates
>> are not minimums.” is pure semantics. The burden of proof is with you
>> providing fossil evidence or a new dataset that, when calibrated,
>> contradicts the previous studies.
>>
>> Ken also mentions the Malagasy fauna as having recent elements that
>> precede its split from Gondwana, and he is correct in this regard as
>> well. There are truly ancient lineages that are vicariant but much
>> more recent ones that cannot have arrived by means other than
>> dispersal (e.g. The dung beetle fauna is a combination). That is my
>> bit of evidence. If you can provide counterfactual evidence that can
>> be profitably discussed then that would be great. Semantics not so
>> much.
>>
>> Have a good one.
>>
>> On 11 June 2018 at 05:26, John Grehan <calabar.john at gmail.com> wrote:
>> > Hi Ken,
>> >
>> > My comments below.
>> >
>> > “ I've been reading a variety of papers on the debate (beginning about
>> > 2005) between Alan de Queiroz (and others) on the one hand and Michael
>> > Heads (and others, incl. John Grehan) on the other. I have come to the
>> > conclusion that both sides represent polar opposites in the debate
>> > between
>> > oceanic dispersal and vicariance. The truth is probably somewhere in
>> > between, meaning that both sides are right about some cases, but wrong
>> > in
>> > others. Not at all surprising. “
>> >
>> >
>> >
>> > There is no evidence that the ‘truth’ is ‘probably’ somewhere inbetween.
>> >
>> >
>> >
>> > “ Perhaps the strongest case for a large number of oceanic dispersals is
>> > probably from the African mainland to Madagascar. “
>> >
>> >
>> >
>> > What is the purported evidence?
>> >
>> >
>> >
>> > “but there is apparently evidence that some of those dispersals were
>> > along
>> > island chains that no longer exist.”
>> >
>> >
>> >
>> > What is the purported evidence?
>> >
>> >
>> >
>> > “Whether such islands existed or not,”
>> >
>> >
>> >
>> > Then there is no actual evidence?
>> >
>> >
>> >
>> > “the debate between the two sides seems to be largely centered on
>> > molecular
>> > estimates of divergence (about which Grehan seems to repeatedly complain
>> > ad
>> > nauseum). “
>> >
>> >
>> >
>> > That comes across as a misrepresentation (unintentional I am sure). I do
>> > not complain about molecular estimates of divergence, I only complain
>> > about
>> > minimums being misrepresentated as actual or maximal. There is a
>> > difference!
>> >
>> >
>> >
>> > “Therefore, my increasing reluctance to respond to his continued
>> > "baiting".
>> >
>> >
>> >
>> > ????
>> >
>> >
>> >
>> > “ If he wants evidence, there is lots of evidence in the literature from
>> > many authors (many who seem to be somewhat more objective than Alan de
>> > Queiroz). “
>> >
>> >
>> >
>> > Then state what is the purported evidence. No good just saying so.
>> >
>> >
>> >
>> > “The case for oceanic dispersal from Australia (including Tasmania) to
>> > New
>> > Zealand is admittedly even more controversial. That controversy not
>> > only
>> > involves molecular estimates of divergence,”
>> >
>> >
>> > It only involves the Big Lie about molecular estimates.
>> >
>> >
>> >
>> > “but also whether or not New Zealand was completely submerged at some
>> > time
>> > in the mid Cenozoic.”
>> >
>> >
>> >
>> > This never had legs to begin with and has been generally buried by
>> > geologists and even orthodox biogeographers.
>> >
>> >
>> >
>> > “ Therefore, I am playing devil's advocate in suggesting how one or two
>> > species of Nothofagus could have rafted from Tasmania to New Zealand in
>> > the
>> > middle of the Cenozoic. Maybe they did and maybe they didn't, but both
>> > possibilities should be kept in mind. “
>> >
>> > If there is evidence for rafting then sure, consider it.
>> >
>> >
>> >
>> > “Given the long-standing debate between Alan de Queiroz and Michael
>> > Heads,
>> > I find the Nothofagus case the most challenging (even though some
>> > earlier
>> > Nothofagus dispersals seem likely to have been due to vicariance over
>> > land
>> > in Gondwana).”
>> >
>> >
>> >
>> > Nothofagus is not a ‘Gondwana’ group.
>> >
>> >
>> >
>> > “Nothofagus distribution could be due to a combination of both
>> > vicariance
>> > and some cases of more recent oceanic dispersal.”
>> >
>> > Or not. But panbiogeography shows clearly that such a combination does
>> > not
>> > have to be invented.
>> >
>> >
>> > John Grehan
>> >
>> >
>> > On Sun, Jun 10, 2018 at 10:25 PM, Kenneth Kinman <kinman at hotmail.com>
>> > wrote:
>> >
>> >> Hi all,
>> >>
>> >> I've been reading a variety of papers on the debate (beginning
>> >> about 2005) between Alan de Queiroz (and others) on the one hand and
>> >> Michael Heads (and others, incl. John Grehan) on the other. I have
>> >> come to
>> >> the conclusion that both sides represent polar opposites in the debate
>> >> between oceanic dispersal and vicariance. The truth is probably
>> >> somewhere
>> >> in between, meaning that both sides are right about some cases, but
>> >> wrong
>> >> in others. Not at all surprising.
>> >>
>> >> Perhaps the strongest case for a large number of oceanic
>> >> dispersals
>> >> is probably from the African mainland to Madagascar. And the case for
>> >> numerous oceanic dispersals between the African mainland and South
>> >> America
>> >> (when they were closer together) is more controversial, but there is
>> >> apparently evidence that some of those dispersals were along island
>> >> chains
>> >> that no longer exist. Whether such islands existed or not, the debate
>> >> between the two sides seems to be largely centered on molecular
>> >> estimates
>> >> of divergence (about which Grehan seems to repeatedly complain ad
>> >> nauseum). Therefore, my increasing reluctance to respond to his
>> >> continued
>> >> "baiting". If he wants evidence, there is lots of evidence in the
>> >> literature from many authors (many who seem to be somewhat more
>> >> objective
>> >> than Alan de Queiroz).
>> >>
>> >> The case for oceanic dispersal from Australia (including
>> >> Tasmania)
>> >> to New Zealand is admittedly even more controversial. That controversy
>> >> not
>> >> only involves molecular estimates of divergence, but also whether or
>> >> not
>> >> New Zealand was completely submerged at some time in the mid Cenozoic.
>> >> Therefore, I am playing devil's advocate in suggesting how one or two
>> >> species of Nothofagus could have rafted from Tasmania to New Zealand in
>> >> the
>> >> middle of the Cenozoic. Maybe they did and maybe they didn't, but both
>> >> possibilities should be kept in mind. Given the long-standing debate
>> >> between Alan de Queiroz and Michael Heads, I find the Nothofagus case
>> >> the
>> >> most challenging (even though some earlier Nothofagus dispersals seem
>> >> likely to have been due to vicariance over land in Gondwana).
>> >> Nothofagus
>> >> distribution could be due to a combination of both vicariance and some
>> >> cases of more recent oceanic dispersal.
>> >>
>> >> ------------------Ken
>> >>
>> >>
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