Challenges And Possibilities

Reply from Doug Markle regarding an attempt to quantify the prospect of meaningfully pure alvordensis genome remaining in ***** Creek.

—–Original Message—–

From: Kortum of Discovery
Sent: Monday, February 28, 2011 11:51 AM
To: ‘Markle, Douglas F – FW’
Cc: ‘Shannon Hurn’
Subject: Attempt to Quantify Potential for Pure Alvord Genome

Thanks Doug, for the detailed reply and the clarification of some of the (many) complications that the (sorting of the) genetics of these trout present.   I believe that you have landed on the equivalent premise that Dr. Behnke expressed when he affirmed the presence of Alvord phenotypes in ***** in 2006 (though you outlined the reasons to arrive at that conclusion in further detail).

If/when a “selective breeding” program is achieved for the Alvord phenotypes in ***** Creek; it certainly should be one for the textbooks.  Perhaps nature lovers and native trout enthusiasts would appreciate the effort all the more—since these trout seem to have been “targeted victims” of hybridization in multiple situations . . .

The Alvords, though strong in many unique respects, do seem frail in other considerations. I hope and expect that you’re right; that the “genetic refresh” from the other cutthroat strains may in some ways strengthen the overall survival prospects for these trout.

Thanks again for the input.

Respectfully,

David and Carmela Kortum

—–Original Message—–

From: Markle, Douglas F – FW
Sent: Monday, February 28, 2011 9:08 AM
To: Kortum of Discovery
Cc: Shannon Hurn
Subject: Attempt to Quantify Potential for Pure Alvord Genome

David,

You need to make a lot of simplifying assumptions to begin that process. I know you understand that, but the problems with them are many, and the primary one is that we do not know the rate of introgression per year, other than it was between 0 and 100%; further, it probably varied over time. But to your larger point, I’d be looking for congruence of phenotype with one or more genetic markers and I’d be looking in those east slope Steens streams as well as *****. There are just too many possibilities for what you might find to predict an outcome and a hybrid swarm is as likely as anything. The other “solution” is simply to do the “breeder” route, stick some in a hatchery, or stream, and select for phenotypes you want. That will likely get you something that is inbred, but the whole concept of “purity” is based on inbreeding. Again we simply don’t know what was there “in the beginning” – whenever you want to define that point in time. Zoogeographically, at some point in time, a common ancestor gave rise to Willow Whitehorse and Alvord trouts. If there was separation of that ancestor and two distinct “forms” evolved, we cannot predict if there was complete lineage sorting. For example, suppose the ancestor had individuals with 100 spots, 75 spots, 50 spots and 25 spots (i.e., it was polymorphic). When isolated, one population might drift, or be selected for, 100 spots while the other goes towards 25 spots. If lineage sorting is not complete, each population might still have individuals with every spotting pattern – the ancestral polymorphic condition – even though the population as a whole is mostly either 100 or 25. You can substitute allele for spots and the story is the same. Basically, with this scenario, when you find a 100 spot fish in the 25 spot population it is not evidence of hybridization – it is ancestral polymorphism with incomplete lineage sorting. Now suppose you know that someone has been dumping fish from one place to another and when you find a 100 spot fish in the 25 spot population, you think it is from the 100 spot population. But you might be wrong. The solution is the highly variable microsats which, if you set it up properly and if the dumping was recent,  will tell you if that 100 spot fish is or is not part of the 25 spot population. If the ***** fish are all part of an interbreeding group, you’d never get anything “pure”. Maybe the solution, if there is a hybrid swarm, is the ‘breeder’ route to move the most Alvord-like fish back and cull their non-Alvord progeny. Over time you might select for the Alvord phenotype even though genetically it has some other lineages in it. One objective, I think, is to have something that can survive the conditions in the basin. The genetic mixing could potentially help that outcome – just trying to be the glass-half-full guy.

Doug

Douglas F. Markle, Dept. Fisheries & Wildlife, 104 Nash Hall, Oregon State University, Corvallis, OR 97331-3803

Doug Markle | Professor of Fisheries | OSU Department of Fish and Wildlife

Introgression in Fishes

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About kortumofdiscovery

Kortum of Discovery (a slight play on Lewis & Clark's Corps of Discovery) is a family team that is Affirming the Exceptional Beauty of Nature, one Adventure at a Time. With a focus toward rare and endangered species in the Great Basin and American west: discoveries, unique methodologies, and many “tall tales to tell” are continually being shared around the campfire!
This entry was posted in ***** Creek Sampling, Fisheries Biology and Genetics, Observations, Progress - Reply - Response - Status. Bookmark the permalink.

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