Tests of evolutionary and genetic rescue using flour beetles, Tribolium castaneum, experimentally evolved to thermal conditions

Lewis, Rebecca ORCID: https://orcid.org/0000-0003-4739-0280, Pointer, Michael D. ORCID: https://orcid.org/0000-0002-7926-330X, Friend, Lucy, Gage, Matthew J. G. and Spurgin, Lewis G. (2024) Tests of evolutionary and genetic rescue using flour beetles, Tribolium castaneum, experimentally evolved to thermal conditions. Ecology and Evolution, 14 (5). ISSN 2045-7758

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Abstract

Small, isolated populations are often characterised by low levels of genetic diversity. This can result in inbreeding depression and reduced capacity to adapt to changes in the environment, and therefore higher risk of extinction. However, sometimes these populations can be rescued if allowed to increase in size or if migrants enter, bringing in new allelic variation and thus increasing genetic diversity. This study uses experimental manipulation of population size and migration to quantify their effects on fitness in a challenging environment to better understand genetic rescue. Using small, replicated populations of Tribolium castaneum experimentally evolved to different temperature regimes we tested genetic and demographic rescue, by performing large-scale manipulations of population size and migration and examining fitness consequences over multiple generations. We measured fitness in high temperature (38°C) thermal lines maintained at their usual ‘small’ population size of N = 100 individuals, and with ‘large’ scaled up duplicates containing N≈10,000 individuals. We compared these large lines with and without migration (m = 0.1) for 10 generations. Additionally, we assessed the effects of outcrossing at an individual level, by comparing fitness of hybrid (thermal line × stock) offspring with within-line crosses. We found that, at the population level, a rapid increase in the number of individuals in the population resulted in reduced fitness (represented by reproductive output and survival through heatwave conditions), regardless of migration. However, at an individual level, the hybrid offspring of migrants with native individuals generally demonstrated increased longevity in high temperature conditions compared with individuals from thermal selection lines. Overall, these populations showed no evidence that demographic manipulations led to genetic or evolutionary rescue. Following the effects of migration in individuals over several generations may be the next step in unravelling these conflicting results. We discuss these findings in the context of conservation intervention.

Item Type:	Article
Additional Information:	Data availability statement: The data to support the findings of this study are available in Dryad https://datadryad.org/stash/share/oF9PqTY8SIdNse-UDcpcG-AyG9_xmJJ68nqK6ZU4WEg. Funding information: This research was supported by a UEA-funded PhD studentship to RL, a Biotechnology and Biological Sciences Research Council (BBSRC) studentship to MDP (BB/M011216/1) through the Norwich Research Park Doctoral Training Partnership and a BBSRC Future Leader fellowship to LGS (BB/N011759/1).
Faculty \ School:	Faculty of Science > School of Biological Sciences
UEA Research Groups:	Faculty of Science > Research Groups > Biosciences Teaching and Education Research
Depositing User:	LivePure Connector
Date Deposited:	01 Nov 2024 09:30
Last Modified:	03 Nov 2024 07:31
URI:	https://ueaeprints.uea.ac.uk/id/eprint/97408
DOI:	10.1002/ece3.11313

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