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

John Grehan calabar.john at gmail.com
Mon Dec 21 15:06:45 CST 2020


Hi Ken. See below

 They say: "Our estimates indicate that divergence between the clades
comprising New World and Old World aplocheiloids occurred during the
Eocene, about 50 Mya, much more recent than the Gondwanan fragmentation
scenario assumed in previous studies."

So they say. But what is the evidence? Ken, all you ever seem to do is post
assertions, never specifying the evidence.

 The molecular evidence in 2017 supports my theory.

What is the molecular evidence?

Cheers,

John Grehan



On Mon, Dec 21, 2020 at 3:40 PM Kenneth Kinman via Taxacom <
taxacom at mailman.nhm.ku.edu> wrote:

> Hi All,
>       Rivulidae (a.k.a. Cynolebiini) are New World killifish once thought
> to have arisen in the Cretaceous before South America fully separated from
> Africa.  However, molecular evidence in 2017 indicates they arose in the
> Eocene.   They say: "Our estimates indicate that divergence between the
> clades comprising New World and Old World aplocheiloids occurred during the
> Eocene, about 50 Mya, much more recent than the Gondwanan fragmentation
> scenario assumed in previous studies. This estimation is nearly synchronous
> to estimated splits involving other South American and African vertebrate
> clades, which have been explained by transoceanic dispersal through an
> ancient Atlantic island chain during the Palaeogene."
>       This makes me quite happy since I brought up this possibility back
> in 2014, in a post here on Taxacom entitled: transoceanic "rafting" fish
> (great candidate).
>       The early branching genus Kryptolebias just happens to be a great
> candidate for a fish that could disperse on a raft of vegetation from
> Africa to South America:   (1) It's not only very tolerant of salt water,
> but also and more importantly (2) it can survive out of water for weeks at
> a time (66 days in one case).  (3) And guess where Kryptolebias marmoratus
> spends much of its time while out of the water----in logs and cavities of
> trees (which would be the main structural components of a large
> transoceanic raft).
>          Those are the three things I thought of offhand which pointed to
> possible trans-Atlantic dispersal.  But then I began wondering about yet
> another strange thing about Kryptolebias fish.  They often exhibit various
> types of hermaphroditism, and even its most extreme form
> (self-fertilization, which is apparently absent in vertebrates except for
> Kryptolebias).  So just a few of these fish (or even a single individual)
> could have established a population on another continent.   The molecular
> evidence in 2017 supports my theory.
> https://www.sciencedirect.com/science/article/abs/pii/S1055790317300386?casa_token=ONKSbcnOLNEAAAAA:roWXxXgD1F0NqnWh9fozphZ4BbyAngOtCQwxXkyr552h7rNz1M366R2yniah-HK5hDFbRaaV
>
>                                   ------------------Ken
>
>
> ----------------------------------------------------------------------------------------------------------------------------
>
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