[Taxacom] fossil potato relative

Thu Jun 14 20:17:17 CDT 2018

Which illustrates well why to treat all molecular divergence estimates as
minimums. That way at least one is not skewing history to fit and not so
critical if fossils are missed (which one would hope that a proper effort
was made in that regard).

John Grehan

On Thu, Jun 14, 2018 at 9:03 PM, Scott Thomson <scott.thomson321 at gmail.com>
wrote:

> I have to say also I find the reliance on molecular dates in recent times
> disturbing. I have seen dates for groups of 23 mya, 35 mya, and 52 mya (3
> separate published papers) on a group that had an actual fossil, a good
> one, that was well dated to over 100 mya. I also find the assumptions of
> molecular dates to be rather daring ones and a bit disturbing when I
> realise that in many cases the fossils used to calibrate such tests are
> obtained by obtaining info from a quick perusal of Fossilworks. I take
> molecular dates with a grain of salt.
>
> Cheers Scott
>
> On Thu, Jun 14, 2018 at 8:54 PM, John Grehan <calabar.john at gmail.com>
> wrote:
>
> > Probably just being polite :)
> >
> > Here is what they said in their article. Note the first sentence in
> > particular.
> >
> > "Our results reinforce the emerging pattern
> > wherein numerous fossil plant taxa from Gondwanan
> > Patagonia and Antarctica are substantially
> > older than their corresponding molecular
> > dates (26, 27), demonstrating Gondwanan history
> > for groups conjectured to have post-Gondwanan
> > origins under entirely different paleogeographic
> > and paleoclimatic scenarios. Likewise, the derived
> > position of the newly identified fossil species
> > shows that the origins and diversification
> > of Solanaceae must have taken place at a much
> > earlier time than previously thought, considerably
> > before final Gondwanan breakup. Other
> > regions of Gondwana are also likely to have
> > played prominent roles in Solanaceae evolution,
> > especially Antarctica, which has produced
> > other important asterid fossils (27). Moreover,
> > the newly identified fossils directly help to
> > resolve temporal inconsistencies between the
> > evolutionary timing of Solanaceae and its herbivores
> > and mutualists (28). The large fossil
> > berry strongly implicates trophic associations
> > with animals, as seen in extant Physalis (29).
> > Today, Physalis inhabits South, Central, and
> > North America, and Mexico is its center of diversity
> > (2). Thus, the fossils establish a rare link
> > to extant New World floras from late-Gondwanan
> > Patagonian assemblages, whose living relatives
> > are mostly concentrated in the Old World tropics
> > and subtropics."
> >
> > On Thu, Jun 14, 2018 at 8:21 PM, David Campbell <pleuronaia at gmail.com>
> > wrote:
> >
> > > "The fossils underpin the need for researchers to be careful"
> > >
> > > Why not conclude "the fossils show that the molecular clock dates were
> > > wrong"?  Calibration, calculation, and interpretation of molecular
> clocks
> > > all have serious problems - why use them?
> > >
> > > On Thu, Jun 14, 2018 at 1:52 PM, John Grehan <calabar.john at gmail.com>
> > > wrote:
> > >
> > > > Not making any judgement about this one, but notice comment on
> > molecular
> > > > clocks at the end.
> > > >
> > > > John Grehan
> > > >
> > > > http://www.iflscience.com/plants-and-animals/
> 52millionyearold-fossil-
> > > > relative-to-the-potato-discovered-in-patagonia/
> > > >
> > > > Despite becoming ubiquitous in almost every corner of the world,
> > > > surprisingly little is known about the deep evolutionary history of
> the
> > > > group of plants that gave rise to potatoes, tomatoes, and tobacco.
> > > > Now, researchers
> > > > have found
> > > > <http://phys.org/news/2017-01-south-american-fossil-
> > > > tomatillos-nightshades.html>
> > > >  just how far back these organisms go, with the discovery of a fossil
> > > > relative that dates back to 52 million years ago, tens of millions of
> > > years
> > > > older than previously thought.
> > > >
> > > > The fossil belongs to a fragile berry of a plant known as a
> tomatillo,
> > or
> > > > ground cherry. They form fruit that is often surrounded by a thin,
> > papery
> > > > lantern, making it difficult for them to be fossilized
> > > > <http://www.bbc.co.uk/news/science-environment-38511034>. Members of
> > the
> > > > *Physalis* genus, they form a small branch of the nightshade family,
> > > which
> > > > in turn includes many commercially important crops, from potatoes
> > > > and petunias to chillies and aubergines.
> > > >
> > > > The only fossil fruits ever found from this family of almost 2,000
> > > species
> > > > of plants, the two specimens were discovered in a fossilized
> rainforest
> > > > that once grew across Patagonia in South America. With a lack of
> > > available
> > > > fossils for this group of plants, researchers have had to rely on
> > > molecular
> > > > dates for when the nightshade plants first evolved, and had settled
> on
> > > the
> > > > figure of around 35 to 51 million years old, while the tomatillo was
> > > > thought to be a relative newcomer at only 10 million years old.
> > > >
> > > > This new discovery, however, completely changes this. The fossils,
> > dating
> > > > to 52 million years ago, show that the ground cherries are actually a
> > > > relatively ancient branch of the nightshade family. “We exhaustively
> > > > analyzed every detail of these fossils in comparison with all
> potential
> > > > living relatives and there is no question that they represent the
> > world's
> > > > first physalis fossils and the first fossil fruits of the nightshade
> > > > family,” says
> > > > <http://phys.org/news/2017-01-south-american-fossil-
> > > > tomatillos-nightshades.html>
> > > >  Professor Peter Wilf, from Pennsylvania State University.
> > > >
> > > > The fossils underpin the need for researchers to be careful when
> > deducing
> > > > an organism's evolutionary age solely from molecular clocks.
> > > > _______________________________________________
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> > > >
> > > > Nurturing Nuance while Assaulting Ambiguity for 31 Some Years,
> > 1987-2018.
> > > >
> > >
> > >
> > >
> > > --
> > > Dr. David Campbell
> > > Associate Professor, Geology
> > > Department of Natural Sciences
> > > Box 7270
> > > Gardner-Webb University
> > > Boiling Springs NC 28017
> > > _______________________________________________
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> > >
> > > Nurturing Nuance while Assaulting Ambiguity for 31 Some Years,
> 1987-2018.
> > >
> > _______________________________________________
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> > Nurturing Nuance while Assaulting Ambiguity for 31 Some Years, 1987-2018.
> >
>
>
>
> --
> Scott Thomson
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> Nurturing Nuance while Assaulting Ambiguity for 31 Some Years, 1987-2018.
>