Timing and Fitness Consequences of Introgression in Speciation

Timing and Fitness Consequences of Introgression in Speciation | Authorea try { document.documentElement.classList.add('js'); } catch (e) { } var _gaq = _gaq || []; _gaq.push(['_setAccount', 'G-8VDV14Y67G']); _gaq.push(['_trackPageview']); (function() { var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true; ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s); })(); Skip to main content Preprints Collections Wiley Open Research IET Open Research Ecological Society of Japan All Collections About About Authorea FAQs Contact Us Quick Search anywhere Search for preprint articles, keywords, etc. Search Search ADVANCED SEARCH SCROLL This is a preprint and has not been peer reviewed. Data may be preliminary. 29 January 2025 V1 Latest version Share on Timing and Fitness Consequences of Introgression in Speciation Author : Ryo Yamaguchi 0000-0003-3545-7513 [email protected] Authors Info & Affiliations https://doi.org/10.22541/au.173813779.95267399/v1 626 views 151 downloads Contents Abstract Supplementary Material Information & Authors Metrics & Citations View Options References Figures Tables Media Share Abstract During adaptation, gene flow can either accelerate or impede species divergence, sparking intense debate about how introgression shapes speciation. Although introgression is widely recognized for introducing genetic novelty, the precise conditions under which it promotes or suppresses reproductive isolation remain unclear, particularly when environmental differences and population dynamics vary. Here, using Fisher's geometric model, we examine how the timing and magnitude of migration influence adaptation and reproductive barriers in both mutation-order and ecological speciation scenarios. We show that early-phase or constant gene flow can facilitate evolutionary rescue for populations adapting to a shared optimum, whereas late-phase migration often delays final adaptation due to the introgression of large-effect mutations in initially isolated populations. In mutation-order speciation, parallel adaptation often reduces hybrid breakdown, whereas, in ecological speciation, alleles beneficial in one environment can be maladaptive in the other. Under both scenarios, early or continuous gene flow promotes allele sharing that eases adaptation but undermines reproductive isolation. We also find that intermediate levels of parental divergence can maximize the success of hybrid lineages, offering insights into when homoploid hybrid speciation may arise. Overall, this study clarifies how gene flow timing modulates the balance between adaptive introgression and isolating barriers. By integrating demography with fitness landscapes, we provide a theoretical framework to interpret genomic patterns of introgression and understand when it accelerates or hinders speciation. Supplementary Material File (manuscript.docx) Download 324.88 KB Information & Authors Information Version history V1 Version 1 29 January 2025 Copyright This work is licensed under a Non Exclusive No Reuse License. Keywords evolutionary rescue fisher’s geometric model gene flow hybridization postzygotic isolation Authors Affiliations Ryo Yamaguchi 0000-0003-3545-7513 [email protected] Hokkaido University View all articles by this author Metrics & Citations Metrics Article Usage 626 views 151 downloads .FvxKWukQNSOunydq8rnd { width: 100px; } Citations Download citation Ryo Yamaguchi. Timing and Fitness Consequences of Introgression in Speciation. Authorea . 29 January 2025. DOI: https://doi.org/10.22541/au.173813779.95267399/v1 If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download. For more information or tips please see 'Downloading to a citation manager' in the Help menu . Format Please select one from the list RIS (ProCite, Reference Manager) EndNote BibTex Medlars RefWorks Direct import Tips for downloading citations document.getElementById('citMgrHelpLink').addEventListener('click', function() { popupHelp(this.href); return false; }); $(".js__slcInclude").on("change", function(e){ if ($(this).val() == 'refworks') $('#direct').prop("checked", false); $('#direct').prop("disabled", ($(this).val() == 'refworks')); }); View Options View options PDF View PDF Figures Tables Media Share Share Share article link Copy Link Copied! Copying failed. 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