[Taxacom] Molecular evidence (in 2017) supports my 2014 theory about rafting killifish

[Scott Monks]

Hello all;     One of the things about Biology that is the most fascinating
is that "Things are not ALWAYS the same''--I'll explain.       In Chemistry
and Physics there are many laws and rules (things that ALWAYS are ture,
with no exceptions; i.e., E=m*(c squared), as far as we know, this is
ALWAYS true), but in Biology we have few, if any, rules or laws.  On the
other hand, we have many "principles" and "theories" (things that we can
generally expect to be true but which have few to many exceptions); i.e.,
Darwin's "theory" of evolution, which is, despite all the evidence in
its favor, not a "rule".
     Fahrenholz' so-called "rule" probably should have been called
"Fahrenholz' principle".  Yes, we should expect that manu, maybe the
majority, of cases of speciation of obligate parasites (or obligate
herbivores, etc.) are cases of co-speciation (when the host speciates its
parasites also speciate, maybe with a time lag).  However, this is not a
100% hard and fast "rule".  There are many cases of host-switching,
extinction, and missing-the-boat, etc., and, in some cases, failure of the
parasite to speciate--that is why it is not a "rule".
     For a more detailed discussion of the many types of events of host and
parasite evolution, I suggest the book: Clayton, D. H., and J. Moore.
 1997.  Host-parasite evolution: general principles and avian models.  In
Vol.  (eds.).  Oxford University Press, New York, 473 p.
     A random article on bird lice that I just happened to have at hand is: de
Moya, R. S., J. M. Allen, A. D. Sweet, K. K. O. Walden, R. L. Palma, V. S.
Smith, S. L. Cameron, M. P. Valim, T. D. Galloway, J. D. Weckstein, and K.
P. Johnson.  2019.  Extensive host-switching of avian feather lice
following the Cretaceous-Paleogene mass extinction event.  Communications
Biology 2:445. Additional information on this article is below.

     My doctoral professor once remarked that a good biologist must not be
looking for biological systems that fit the patterns of all the other
systems--they add nothing new to science and actually are boring.  He went
on to say that I should be looking for systems that do NOT fit the
patterns, that these are the interesting ones and the ones worthy of
further study to find out why they don't fit the known patterns.  This was
one of the many important things he taught me.

     This might not be lending much to this discussion, but it definitely
is pertinent to remember that, no matter which side of an argument we take,
we must strive to be flexible, and not think that everything, every thing,
fits the same pattern, that there, in Biology, are always exceptions to any
so-called rule....although these rules/principles are always a good place
to start and provide a testable null hypothesis.
DOI: 10.1038/s42003-019-0689-7Abstract: Nearly all lineages of birds host
parasitic feather lice. Based on recent phylogenomic studies, the three
major lineages of modern birds diverged from each other before the
Cretaceous-Paleogene (K-Pg) mass extinction event. In contrast, studies of
the phylogeny of feather lice on birds, indicate that these parasites
diversified largely after this event. However, these studies were unable to
reconstruct the ancestral avian host lineage for feather lice. Here we use
genome sequences of a broad diversity of lice to reconstruct a phylogeny
based on 1,075 genes. By comparing this louse evolutionary tree to the
avian host tree, we show that feather lice began diversifying on the common
ancestor of waterfowl and landfowl, then radiated onto other avian lineages
by extensive host-switching. Dating analyses and cophylogenetic comparisons
revealed that two of three lineages of birds that diverged before the K-Pg
boundary acquired their feather lice after this event via host-switching.

On Sat, Jan 2, 2021 at 11:39 PM Roland Bergman-Sun via Taxacom <
taxacom at mailman.nhm.ku.edu> wrote:

> And still, annoyingly, animals move and seeds are dispersed, even over
> long distances. Who could imagine that this ever would have an effect
> on anything?
>
> As fascinating as these interminable reruns are, I can't help but
> notice the parallel between this and Fahrenholz' rule.
>
> Fahrenholz' rule states that ectoparasitic animals that do not have a
> free-living stage are bound definitely to their hosts, and thus will
> speciate in parallel to these. Stated differently, it predicts that
> dispersal from one host to another is of no practical or evolutionary
> importance, and that vicariance on a single host lineage is the
> exclusive mechanism that dominates louse evolution. This results in
> the famous "Parasite phylogeny should mirror host phylogeny", which
> inevitably lead to the idea that *any* louse species found on a novel
> host species must represent a new species; if on a new host family or
> host order, it may represent a new louse genus. Morphology was
> speedily disregarded by the maxim "It is methodologically more correct
> to say that we don't know the morphological differences than to state
> that there are none" (Eichler, 1942 I think). Multitudes of species
> were then described based on host associations (or with the regular
> phrase "Species X is well separated from other species by characters
> of the head", with no details or detailed illustrations). This
> artificial host specificity was subsequently taken as evidence for
> Fahrenholz' rule, in an excellent example of circular reasoning.
> .....
>


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Correo/ Mail

Dr. Scott Monks
Universidad Autónoma del Estado de Hidalgo (UAEH)
Centro de Investigaciones Biológicas (CIB)
Apdo. Postal 1-10
Pachuca, C.P. 42001
Hidalgo, México.


Mensajería/ Courier

Universidad Autónoma del Estado de Hidalgo (UAEH)
Centro de Investigaciones Biológicas (CIB)
Ciudad Universitaria, Carretera Pachuca-Tulancingo Km. 4.5 S/n
Pachuca  C.P. 42184
Hidalgo, México

[Tel 01(771)717-2000 Ext. 6658, 6640]
[Fax 01(771)717-2112]

pagina / web page
http://www.uaeh.edu.mx/investigacion/biologia/investigadores/monks_sheets.htm

correo electrónico / email
<smonks at uaeh.edu.mx> y <scottmonks at hotmail.com>
<monks.scott at gmail.com>
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