Immigration allows population persistence and maintains genetic diversity despite an attempted experimental extinction

Widespread fragmentation and degradation of habitats make organisms increasingly vulnerable to declines in population. Immigration is a key process potentially affecting the rescue and persistence of populations in the face of such pressures. Field research addressing severe demographic declines in the context of immigration among interconnected local populations is limited due to difficulties in detecting such demographic events and the need for long-term monitoring of populations. In a 17-subpopulation metapopulation of the butterfly, Parnassius smintheus, all adults observed in two adjacent patches were removed over eight consecutive generations. Despite this severe and long-term reduction in survival and reproduction, the targeted populations did not go extinct. Here, we use genetic data to assess the role of immigration versus in situ reproduction in allowing the persistence of these populations. We genotyped 471 samples collected from the targeted populations throughout the remova..., The Jumpingpound Ridge metapopulation occurs within a network of 17 patches of alpine meadow habitat ranging in size from 0.2 ha to 22.7 ha. This system has been the subject of long-term population monitoring and genetic sample collection since 1995, with mark-recapture performed during the annual flight season to monitor population size and movement. The removal experiment on patches P and Q was conducted from 2001 to 2008 to investigate the effects of severe and continuous population reduction in patches P and Q on the population dynamics in surrounding, neighbouring patches . Through the course of the experiment, patches P and Q were surveyed every one to three days during the flight season each year, and all observed butterflies were captured by hand netting and removed from the site. In total, 4,830 butterflies were removed from P and Q over the eight-year period. The removed individuals were labelled with the date and location of capture, and then stored, dried, and pinned in a co..., , ***Parnassius smintheus*** **(Rocky Mountain Apollo) Removal Experiment SNP (Single Nucleotide Polymorphism) Genotype Data**

This dataset consists of three sheets: 01-08 PQ Removal, 05 Surrounding Populations, and 08 Surrounding Populations, each containing SNP (single nucleotide polymorphism) genotype data of *Parnassius smintheus* (Rocky Mountain Apollo), collected from a metapopulation system of this alpine butterfly in Jumpingpound Ridge, Kananaskis, Alberta, Canada (50° 57'N, 114° 54'W), consisting of 17 alpine meadow habitat patches (Please refer to Figure 1 of [https://doi.org/10.1098/rsos.240557](https://doi.org/10.1098/rsos.240557) for the map of Jumpingpound Ridge including the name and location of each habitat patch).

This population system has been researched since 1995, with population monitoring and genetic sampling being conducted during the summer flight season annually. From 2001 to 2008, all adult individuals found in two adjacent patches, P and Q, were removed annua...