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Rick:</div>
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Very nice example. This idea that a population may be a mixture of distinct, and genetically-determined, strategies/phenotypes (and thus multi-locus polymorphisms) has long been discussed in the evolution literature, and whether this could lead to reproductive
isolation (typically by pre-zygotic mating isolation and subsequent genetic divergence). The major issue is that when the trait is determined by a number of genes, the required alleles must be transmitted in a correlated fashion (the "supergene" concept,
e.g. reduced recombination via the genes locked in a chromosomal inversion--a key early hypothesis for the evolution of mimicry). With unlinked loci, the favorable gene combinations are randomized and must be sorted out via selection, at a cost to the population.</div>
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I enclosed (even though it may not make it through the list-serve filter) the current draft chapter on marker-based mapping (from the in-progress revision of Lynch and Walsh 1998). A lot of now known about the genetics of speciation in Drosophila, and it is
reviewed on pages 7-11. Basically, much is driven by incompatibilities between the X and Y that arise following divergence.</div>
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<div class="PlainText"> Cheers from down-under</div>
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<div class="PlainText">bruce </div>
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<div class="PlainText"> <br>
Bruce Walsh<br>
Professor, Ecology and Evolutionary Biology<br>
Professor, Public Health<br>
Professor, BIO5 Institute<br>
Professor, Plant Sciences<br>
Adjunct Professor, Animal and Comparative Biomedical Sciences<br>
Adjunct Professor, Molecular and Cellular Biology<br>
Member, Graduate Committees on Applied Math, Insect Sciences, Genetics, Statistics<br>
University of Arizona</div>
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<div class="PlainText">Evolution and Selection of Quantitative Traits (Oxford 2018)</div>
<div class="PlainText"><a href="https://global.oup.com/academic/product/evolution-and-selection-of-quantitative-traits-9780198830870" class="OWAAutoLink">https://global.oup.com/academic/product/evolution-and-selection-of-quantitative-traits-9780198830870</a> <br>
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<div class="PlainText"><a href="https://www.amazon.com/gp/product/0198830874" class="OWAAutoLink">https://www.amazon.com/gp/product/0198830874</a><br>
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<div class="PlainText">Genetics and Analysis of Quantitative Traits (Sinauer <Oxford> 1998)<br>
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<div class="PlainText"><a href="https://global.oup.com/academic/product/genetics-and-analysis-of-quantitative-traits-9780878934812" class="OWAAutoLink">https://global.oup.com/academic/product/genetics-and-analysis-of-quantitative-traits-9780878934812</a></div>
<div class="PlainText"><a href="https://www.amazon.com/Genetics-Analysis-Quantitative-Traits-Michael/dp/0878934812" class="OWAAutoLink">https://www.amazon.com/Genetics-Analysis-Quantitative-Traits-Michael/dp/0878934812</a><br>
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Google Scholar</div>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> rcech@nyc.rr.com <rcech@nyc.rr.com><br>
<b>Sent:</b> Sunday, May 29, 2022 2:06 PM<br>
<b>To:</b> Walsh, Bruce - (jbwalsh) <jbwalsh@arizona.edu>; leps-l@mailman.yale.edu <leps-l@mailman.yale.edu><br>
<b>Subject:</b> [EXT]RE: [Leps-l] Monarchs - subspecies, genetics and migration</font>
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<p class="x_MsoNormal">Heartily agree. But does it need to be distance separation? Imagine a population of anteaters w/half-inch claws on average (but with randomly variable claw length), that were used to surviving on grubs at ½” down in a log. If another
set of invasive grubs arrived that lived exclusively at ¾” down, then anteaters with randomly long claws (>= ¾”) could get at those new grubs and might diverge sympatrically, even while co-existing with other anteaters who still could feed on their customary,
shallower-living prey. (This equilibrium might or might not be affected by the new feeding style, depending mainly on whether the long-clawed version tore the crud out of the grub logs to get at their new prey). Things like this are not unheard-of in nature.</p>
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<p class="x_MsoNormal">Just a thought</p>
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<p class="x_MsoNormal">Good discussion,</p>
<p class="x_MsoNormal">Rick</p>
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<p class="x_MsoNormal"><b>From:</b> Leps-l <leps-l-bounces@mailman.yale.edu> <b>On Behalf Of
</b>Walsh, Bruce - (jbwalsh)<br>
<b>Sent:</b> Sunday, May 29, 2022 3:17 AM<br>
<b>To:</b> leps-l@mailman.yale.edu<br>
<b>Subject:</b> [Leps-l] Monarchs - subspecies, genetics and migration</p>
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<p class="x_MsoNormal"><span style="font-size:12.0pt; color:black">I've followed this thread for a little while and have avoided commenting on it. In large part, because it started when I was in Nairobi, and had low band-width. Now my travels have now taken
me to Hobart, with its higher bandwidth! Alas, no collecting/watching in either location, work-related (teaching and on an advisory committee).</span></p>
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<p class="x_MsoNormal"><span style="font-size:12.0pt; color:black">From a genetics standpoint, the issue can be clearly framed in terms of gene exchange. In a classic paper, Sewall Wright (one of the founders of population genetics) noted that a single exchange
of an individual between populations per generation is about all that is needed to keep two neutral subpopulations from diverging (more formally, 4Nm >> 1, where m is the exchange rate and N the population size). So the issue becomes: "is there something
about the migrationing population that results in a drastic reduction in gene exchange with the non-migration population". Unless there is differential mate choice when they come into contact (which they will do each year), don't think the case can be made.</span></p>
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<p class="x_MsoNormal"><span style="font-size:12.0pt; color:black">cheers</span></p>
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<br>
Bruce Walsh<br>
Professor, Ecology and Evolutionary Biology<br>
Professor, Public Health<br>
Professor, BIO5 Institute<br>
Professor, Plant Sciences<br>
Adjunct Professor, Animal and Comparative Biomedical Sciences<br>
Adjunct Professor, Molecular and Cellular Biology<br>
Member, Graduate Committees on Applied Math, Insect Sciences, Genetics, Statistics<br>
University of Arizona</span></p>
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<p class="x_MsoNormal"><span style="font-size:10.0pt; color:black">Evolution and Selection of Quantitative Traits (Oxford 2018)</span></p>
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<p class="x_MsoNormal"><span style="font-size:10.0pt; color:black"><a href="https://global.oup.com/academic/product/evolution-and-selection-of-quantitative-traits-9780198830870">https://global.oup.com/academic/product/evolution-and-selection-of-quantitative-traits-9780198830870</a> </span></p>
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<p class="x_MsoNormal"><span style="font-size:10.0pt; color:black"><a href="https://www.amazon.com/gp/product/0198830874">https://www.amazon.com/gp/product/0198830874</a></span></p>
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<p class="x_MsoNormal"><span style="font-size:10.0pt; color:black">Genetics and Analysis of Quantitative Traits (Sinauer <Oxford> 1998)</span></p>
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<p class="x_MsoNormal"><span style="font-size:10.0pt; color:black"><a href="https://global.oup.com/academic/product/genetics-and-analysis-of-quantitative-traits-9780878934812">https://global.oup.com/academic/product/genetics-and-analysis-of-quantitative-traits-9780878934812</a></span></p>
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<p class="x_MsoNormal"><span style="font-size:10.0pt; color:black"><a href="https://www.amazon.com/Genetics-Analysis-Quantitative-Traits-Michael/dp/0878934812">https://www.amazon.com/Genetics-Analysis-Quantitative-Traits-Michael/dp/0878934812</a></span></p>
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<p class="x_MsoNormal"><span style="font-size:10.0pt; color:black">Google Scholar</span></p>
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