4 replies to this topic

[mattknepley]

The post that follows contains two parts. First, the text of an email forwarded to the Desert Fishes Council's listserve. After the copy of the email is citation material and abstract of a paper proposing a new timeline for Devil's Hole Pupfish evolution. The webpage listed in the citation does not appear to be activated yet. I removed email addresses from the forward. Anyone interested in this preprint who can't find it elsewhere can pm me and I'll email them a copy of the 10 page pdf.


Begin forwarded message:

From: Bruce Turner
Subject: PRSB article "preprint"
Date: January 16, 2016 at 8:50:24 PM PST
To: David Duvernell , "Robert K. Liu"
Dear Dave, Bob and Phil,

Attached to this note is a "preprint" (actually a pdf of page proofs) of an article by Chris Martin, Jacob Crawford, myself, and Lee Simons that will published in the Proceedings of the Royal Society; the online version will appear very shortly, and I will send you a link to it when it is available. There is no need for professional confidentiality at this point, so feel free to share this file with whomever you feel may be interested.

I think it likely that this article will generate some controversy in the fields of fish conservation genetics, and evolutionary genetics in general. It does present a virtually total reappraisal of the ages and extents of geographic isolation and genetic differentiation of the Death Valley pupfish populations. More pointedly, it tends to overthrow the basic assumptions (and research paradigms) about the system that almost all biologists (myself included) have all been making since the time of Carl Hubbs and Robert R. Miller. It will certainly prove unsettling to most workers in the field, and I doubt that it will go long unchallenged. The next few years should be very interesting indeed.

The article will inevitably generate some attention in the public news media. Chris is as sensitive as I am to the possibility that some individuals and government agencies might (mistakenly) view our data as a rationale for relaxing conservation efforts and/or permitting the extirpation of some of the pupfish populations. I want to assure you that Chris will make every effort to contradict and correct this negative and nihilistic view of our data in conversations with the media. Since I am not the senior author, I doubt that very much media attention will be directed at me, but, to the extent that I am queried, I will do the same.

Best regards to you all.
Bruce



Cite this article: Martin CH, Crawford JE,
Turner BJ, Simons LH. 2016 Diabolical survival
in Death Valley: recent pupfish colonization,
gene flow and genetic assimilation in the
smallest species range on earth. Proc. R. Soc. B
20152334.
http://dx.doi.org/10.../rspb.2015.2334


One of the most endangered vertebrates, the Devils Hole pupfish Cyprinodon
diabolis, survives in a nearly impossible environment: a narrow subterranean
fissure in the hottest desert on earth, Death Valley. This species became a
conservation icon after a landmark 1976 US Supreme Court case affirming
federal groundwater rights to its unique habitat. However, one outstanding
question about this species remains unresolved: how long has diabolis persisted
in this hellish environment? We used next-generation sequencing of
over 13 000 loci to infer the demographic history of pupfishes in Death
Valley. Instead of relicts isolated 2 3 Myr throughout repeated flooding of Q1
the entire region by inland seas as currently believed, we present evidence
for frequent gene flow among Death Valley pupfish species and divergence
after the most recent flooding 13 kyr. We estimate that Devils Hole was
colonized by pupfish between 105 and 830 years ago, followed by genetic
assimilation of pelvic fin loss and recent gene flow into neighbouring
spring systems. Our results provide a new perspective on an iconic endangered
species using the latest population genomic methods and support
an emerging consensus that timescales for speciation are overestimated in
many groups of rapidly evolving species.

[Isaac Szabo]

Interesting! That's such a big difference. Is this the first time genetics have been used to try to estimate the age of the population?

[fundulus]

It's a much more comprehensive analysis with better technology, certainly. The small size, oversized head and lost pelvic fins in many wild-type diabolis aren't so much the result of genetic change as they are the result of living in a marginal environment with higher water temperature and limited food. If you keep other pupfish species from that area in equivalent conditions, they also will grow in to a similar phenotype as diabolis. The diabolis kept in various refugia stop looking like their ancestor in a few generations because they're kept in cooler water and are better fed. There's also genetic drift, but it's a peculiar blend of genetic and environment influences. Turner has been working with this group since he was a doctoral student at UCLA and I'm glad he's back with them.

[gerald]

I wonder why does it takes a few generations for the body morphology changes to occur (in either direction)?  if the stunted body form is due to high temp and poor diet, I'd expect it to show up in the 1st generation.

 

... they are the result of living in a marginal environment with higher water temperature and limited food. If you keep other pupfish species from that area in equivalent conditions, they also will grow in to a similar phenotype as diabolis. The diabolis kept in various refugia stop looking like their ancestor in a few generations because they're kept in cooler water and are better fed. ....

[fundulus]

I agree as to expectations. I'd guess there's some epigenetics involved.