Genetic rescue despite outbreeding depression

Genetic rescue despite outbreeding depression | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Genetic rescue despite outbreeding depression Benjamin M. Fitzpatrick This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7837307/v1 This work is licensed under a CC BY 4.0 License Status: Under Revision Version 1 posted 10 You are reading this latest preprint version Abstract Loss of adaptive capacity and risk of inbreeding depression in small populations have been cited as causes of extinction for decades. Population viability and evolutionary potential can be restored by augmenting small populations with genetically diverse immigrants – genetic rescue. However, conservationists are often hesitant to attempt genetic augmentation owing to concerns that introduced alleles could cause outbreeding depression or displacement of locally advantageous alleles. This concern has caused conservation geneticists to recommend against genetic augmentation when presented with any evidence of outbreeding depression. However, population genetics theory demonstrates that genetic rescue is possible despite outbreeding depression if recombination and natural selection can proceed efficiently. Here I present a few simple models combining population genetics and density-dependent population dynamics to illustrate how extinction can be prevented by genetic rescue, even when immigrants and F1 offspring have low fitness. The theory is not new, but its implications are underappreciated. The specters of outbreeding depression and genetic swamping are probably overestimated. An additional, unexpected result is that a single large translocation can result in less genetic swamping than a smaller translocation followed by multiple generations of assisted gene flow. When possible, genetic augmentation and its fitness consequences should be experimentally investigated when population declines are caused or exacerbated by genetic problems. The main challenge in practice is to manage the risk of extinction during the transitional period in which low-fitness genotypes are common in an augmented population. However, this is also the main challenge for managing declining populations without genetic augmentation. Genetics inbreeding outbreeding fitness natural selection population viability Full Text Additional Declarations No competing interests reported. Supplementary Files SimulationCode.pdf Cite Share Download PDF Status: Under Revision Version 1 posted Editorial decision: Revision requested 03 May, 2026 Reviews received at journal 09 Dec, 2025 Reviews received at journal 07 Dec, 2025 Reviewers agreed at journal 16 Nov, 2025 Reviewers agreed at journal 14 Nov, 2025 Reviewers agreed at journal 13 Nov, 2025 Reviewers invited by journal 10 Nov, 2025 Editor assigned by journal 14 Oct, 2025 Submission checks completed at journal 14 Oct, 2025 First submitted to journal 11 Oct, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7837307","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":545702524,"identity":"6f8165bc-e0c8-4f03-91d8-edb348227025","order_by":0,"name":"Benjamin M. Fitzpatrick","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAuklEQVRIie3OIQ+CUBDA8WNsj4Jmk36F92ZgTD/MUaBgJbJnIWGHb8FHgLGRHJkGdgOR4uZjJoPj0Qz3367db3cAFPWHcTUjAuwBGHxGgxgZIhyBrSKA4Elt4li3Sj6mOCj6BGGM6mXipq0nEdmlaFhpZK0G4V3oDIi2IpY0N4kO6Z9CXdkFfCYvLdLZM+HI1WOmoUPcNFTER5E3PlZpGywTx7qL63SOD9u6EcMUnZbJV+XKfYqiKOpXbwV2PHGU3gHyAAAAAElFTkSuQmCC","orcid":"","institution":"University of Tennessee at Knoxville","correspondingAuthor":true,"prefix":"","firstName":"Benjamin","middleName":"M.","lastName":"Fitzpatrick","suffix":""}],"badges":[],"createdAt":"2025-10-11 20:23:10","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7837307/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7837307/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":96343262,"identity":"4c91b0af-4629-4f50-9416-45bbb6a64a4a","added_by":"auto","created_at":"2025-11-20 05:12:54","extension":"docx","order_by":0,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":521774,"visible":true,"origin":"","legend":"","description":"","filename":"geneticrescuedespiteoutbreedingdepression.docx","url":"https://assets-eu.researchsquare.com/files/rs-7837307/v1/542c6bf37e470c07e8e0db51.docx"},{"id":96343261,"identity":"29659ca3-a95b-488a-942e-887430fed944","added_by":"auto","created_at":"2025-11-20 05:12:54","extension":"json","order_by":1,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":3649,"visible":true,"origin":"","legend":"","description":"","filename":"7404a02977674ed9ba6ab06d43914e7a.json","url":"https://assets-eu.researchsquare.com/files/rs-7837307/v1/9862709ae758e0dd849db8f0.json"},{"id":96366157,"identity":"5a95450c-f894-4e8b-940a-36b0c4fd0296","added_by":"auto","created_at":"2025-11-20 10:11:15","extension":"pdf","order_by":2,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":345234,"visible":true,"origin":"","legend":"","description":"","filename":"SimulationCode.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7837307/v1/4e9f4483cae0fe0ecb63d49c.pdf"},{"id":96366981,"identity":"63086bba-f52c-4d75-9fb0-218b0cfff4bd","added_by":"auto","created_at":"2025-11-20 10:12:04","extension":"xml","order_by":3,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":106145,"visible":true,"origin":"","legend":"","description":"","filename":"7404a02977674ed9ba6ab06d43914e7a1enriched.xml","url":"https://assets-eu.researchsquare.com/files/rs-7837307/v1/3ba5c8a857f3fb900df70bf3.xml"},{"id":96366989,"identity":"b481ac54-9ba2-445a-9c88-8939f4046d70","added_by":"auto","created_at":"2025-11-20 10:12:05","extension":"png","order_by":4,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":53447,"visible":true,"origin":"","legend":"","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-7837307/v1/392a22b687b6c7efc2e3090a.png"},{"id":96367363,"identity":"b34c07af-3b3b-4c31-a479-515c1e931381","added_by":"auto","created_at":"2025-11-20 10:12:38","extension":"emf","order_by":5,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":585972,"visible":true,"origin":"","legend":"","description":"","filename":"floatimage2.emf","url":"https://assets-eu.researchsquare.com/files/rs-7837307/v1/e5c3902b0287ddff715304b0.emf"},{"id":96366354,"identity":"45da3513-3dd1-4c9b-b87d-3bc922fabb7f","added_by":"auto","created_at":"2025-11-20 10:11:24","extension":"png","order_by":6,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":63760,"visible":true,"origin":"","legend":"","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-7837307/v1/e806ee738387d98268ce8b67.png"},{"id":96366140,"identity":"3a9c2261-b486-4f52-ad0d-84ab7824787b","added_by":"auto","created_at":"2025-11-20 10:11:14","extension":"emf","order_by":7,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":913200,"visible":true,"origin":"","legend":"","description":"","filename":"floatimage4.emf","url":"https://assets-eu.researchsquare.com/files/rs-7837307/v1/32b7944d60317887fb06b620.emf"},{"id":96366523,"identity":"b32bf772-fff2-4720-bb3a-7b9f33e06011","added_by":"auto","created_at":"2025-11-20 10:11:31","extension":"png","order_by":8,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":68575,"visible":true,"origin":"","legend":"","description":"","filename":"floatimage5.png","url":"https://assets-eu.researchsquare.com/files/rs-7837307/v1/e7230199e5e68a515a931bba.png"},{"id":96343276,"identity":"e0773c34-9da9-4453-a75c-4ff3e566edd9","added_by":"auto","created_at":"2025-11-20 05:12:55","extension":"emf","order_by":9,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":296968,"visible":true,"origin":"","legend":"","description":"","filename":"floatimage6.emf","url":"https://assets-eu.researchsquare.com/files/rs-7837307/v1/0035ca9a21816a3f8b45b468.emf"},{"id":96343267,"identity":"03a445c6-c8ca-4639-a1f1-2f6bc1d94253","added_by":"auto","created_at":"2025-11-20 05:12:55","extension":"png","order_by":10,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":26705,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-7837307/v1/ab8075ccc52e7f51abc1f695.png"},{"id":96366091,"identity":"cd79b4a3-ff1c-40bc-9bdd-0e891c847b14","added_by":"auto","created_at":"2025-11-20 10:11:10","extension":"png","order_by":11,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":4292,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-7837307/v1/7141bdfc9c7a852d751c5892.png"},{"id":96343271,"identity":"c06f762a-52c7-4443-a4bb-e8787fc47eb1","added_by":"auto","created_at":"2025-11-20 05:12:55","extension":"png","order_by":12,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":29395,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-7837307/v1/d386a47b889aa651181cb20c.png"},{"id":96343264,"identity":"469d9296-f7fc-4b85-8178-f45cad115215","added_by":"auto","created_at":"2025-11-20 05:12:55","extension":"png","order_by":13,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":18303,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-7837307/v1/2f3578ff81dd89613a5b1745.png"},{"id":96367638,"identity":"b14b71c7-55ed-4f3d-a4c8-5f96800fa8f0","added_by":"auto","created_at":"2025-11-20 10:13:45","extension":"png","order_by":14,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":31869,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage5.png","url":"https://assets-eu.researchsquare.com/files/rs-7837307/v1/03a8940ecb98d20798b62ef3.png"},{"id":96366649,"identity":"45dcd46b-ca1d-4f54-a17d-86fee404b56d","added_by":"auto","created_at":"2025-11-20 10:11:39","extension":"png","order_by":15,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":5891,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage6.png","url":"https://assets-eu.researchsquare.com/files/rs-7837307/v1/d5bd3cb9755072590d8e390f.png"},{"id":96343273,"identity":"77a05918-d5f9-42d2-965d-2516159f12e8","added_by":"auto","created_at":"2025-11-20 05:12:55","extension":"xml","order_by":16,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":105482,"visible":true,"origin":"","legend":"","description":"","filename":"7404a02977674ed9ba6ab06d43914e7a1structuring.xml","url":"https://assets-eu.researchsquare.com/files/rs-7837307/v1/15aedd4ca9f94932855ab833.xml"},{"id":96367369,"identity":"915e810a-c8e3-49c2-b62a-9a73585dc1fc","added_by":"auto","created_at":"2025-11-20 10:12:38","extension":"html","order_by":17,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":113542,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-7837307/v1/ee4151bc90061c7cef1b0ade.html"},{"id":96369558,"identity":"972e6922-bb3a-4fc0-88c1-9386fad5219a","added_by":"auto","created_at":"2025-11-20 10:21:17","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":583953,"visible":true,"origin":"","legend":"","description":"","filename":"geneticrescuedespiteoutbreedingdepression.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7837307/v1_covered_c4e8315f-66d2-4808-9d8f-fe240d77fb3c.pdf"},{"id":96366988,"identity":"65ae677d-0b58-4e5f-a595-fb3c80bf2243","added_by":"auto","created_at":"2025-11-20 10:12:05","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":345234,"visible":true,"origin":"","legend":"","description":"","filename":"SimulationCode.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7837307/v1/5a70364d5e56b7b53df7f7d3.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Genetic rescue despite outbreeding depression","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"conservation-genetics","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"coge","sideBox":"Learn more about [Conservation Genetics](https://www.springer.com/journal/10592)","snPcode":"10592","submissionUrl":"https://submission.nature.com/new-submission/10592/3","title":"Conservation Genetics","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Genetics, inbreeding, outbreeding, fitness, natural selection, population viability","lastPublishedDoi":"10.21203/rs.3.rs-7837307/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7837307/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eLoss of adaptive capacity and risk of inbreeding depression in small populations have been cited as causes of extinction for decades. Population viability and evolutionary potential can be restored by augmenting small populations with genetically diverse immigrants \u0026ndash; genetic rescue. However, conservationists are often hesitant to attempt genetic augmentation owing to concerns that introduced alleles could cause outbreeding depression or displacement of locally advantageous alleles. This concern has caused conservation geneticists to recommend against genetic augmentation when presented with any evidence of outbreeding depression. However, population genetics theory demonstrates that genetic rescue is possible despite outbreeding depression if recombination and natural selection can proceed efficiently. Here I present a few simple models combining population genetics and density-dependent population dynamics to illustrate how extinction can be prevented by genetic rescue, even when immigrants and F1 offspring have low fitness. The theory is not new, but its implications are underappreciated. The specters of outbreeding depression and genetic swamping are probably overestimated. An additional, unexpected result is that a single large translocation can result in less genetic swamping than a smaller translocation followed by multiple generations of assisted gene flow. When possible, genetic augmentation and its fitness consequences should be experimentally investigated when population declines are caused or exacerbated by genetic problems. The main challenge in practice is to manage the risk of extinction during the transitional period in which low-fitness genotypes are common in an augmented population. However, this is also the main challenge for managing declining populations without genetic augmentation.\u003c/p\u003e","manuscriptTitle":"Genetic rescue despite outbreeding depression","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-11-20 05:12:50","doi":"10.21203/rs.3.rs-7837307/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-05-04T03:19:50+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-12-09T21:47:44+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-12-08T02:22:30+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"201060760493894044330855954897301571560","date":"2025-11-16T06:34:31+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"267123480278800907110941710935213819139","date":"2025-11-14T08:11:58+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"13536300668569409513610482673670537097","date":"2025-11-13T09:05:14+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-11-11T02:37:06+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-10-14T08:54:17+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-10-14T08:53:23+00:00","index":"","fulltext":""},{"type":"submitted","content":"Conservation Genetics","date":"2025-10-11T20:10:34+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"conservation-genetics","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"coge","sideBox":"Learn more about [Conservation Genetics](https://www.springer.com/journal/10592)","snPcode":"10592","submissionUrl":"https://submission.nature.com/new-submission/10592/3","title":"Conservation Genetics","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"51fb35ae-3d81-438a-9644-e156c569d556","owner":[],"postedDate":"November 20th, 2025","published":true,"recentEditorialEvents":[{"type":"decision","content":"Revision requested","date":"2026-05-04T03:19:50+00:00","index":"","fulltext":""}],"rejectedJournal":[],"revision":"","amendment":"","status":"in-revision","subjectAreas":[],"tags":[],"updatedAt":"2026-05-04T03:24:09+00:00","versionOfRecord":[],"versionCreatedAt":"2025-11-20 05:12:50","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7837307","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7837307","identity":"rs-7837307","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}