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Genetic rescue – ameliorating inbreeding depression and restoring genetic diversity of inbred populations through gene flow - is valuable in wildlife conservation. Empirically validated recommendations for genetic rescue supported by evolutionary genetics theory advise maximizing genetic diversity in target populations. Instead, recent papers based on genomic studies of island foxes, Isle Royal wolves, and simulation modeling claim it would be preferable to minimize introduction of harmful variation by avoiding genetic rescue altogether or by selecting partially-inbred sources presumed to have fewer harmful alleles. We examined the assertions and evidence underlying these new recommendations. The claim that long-term persistence of a few small inbred populations invalidates the small population paradigm commits the survivorship fallacy by ignoring population extinctions through inbreeding. The claim that island foxes show no inbreeding depression conflicts with elevated levels of putatively harmful alleles, low fecundity, and island-specific disease susceptibilities. The claim that the history of Isle Royale wolves represents likely outcomes of genetic rescues using immigrants from larger source populations is invalid: the unplanned addition of a single male to an inbred population capped at ~25 individuals does not represent sound genetic rescue. The simulations in Robinson et al. (2018, 2019) and Kyriazis et al. (2019 pre-print) apply several unrealistic assumptions and parameter distributions that disfavor large, outbred sources for genetic rescue. Accordingly, the simulations' conclusions conflict profoundly with those of >120 meta-analysed real datasets, and do not overturn current empirically validated recommendations to maximize genetic diversity in the target population. • Inbreeding and loss of gene diversity are unavoidable in small isolated populations and increase extinction risks • Such populations can be often be rescued by gene flow from another population (genetic rescue) • Gene flow from genetically diverse populations is better at reversing genetic erosion than that from small populations • Proposals to minimize introduction of harmful variation are based on unrealistic simulations that contradict real-life outcomes • Maximizing genetic diversity in the target population is the best current strategy to improve fitness and ability to evolve [ABSTRACT FROM AUTHOR]

Disease epidemics have caused extensive damage to tropical coral reefs and to the reef-building corals themselves, yet nothing is known about the abilities of the coral host to resist disease infection. Understanding the potential for natural disease resistance in corals is critically important, especially in the Caribbean where the two ecologically dominant shallow water corals, Acropora cervicornis and A. palmata, have suffered an unprecedented mass die-off due to White Band Disease (WBD), and are now listed as threatened under the US Threatened Species Act and as critically endangered under the IUCN Red List criteria. Here we examine the potential for natural resistance to WBD in the staghorn coral Acropora cervicornis by combining microsatellite genotype information with in situ transmission assays and field monitoring of WBD on tagged genotypes. We show that six percent of staghorn coral genotypes (3 out of 49) are resistant to WBD. This natural resistance to WBD in staghorn corals represents the first evidence of host disease resistance in scleractinian corals and demonstrates that staghorn corals have an innate ability to resist WBD infection. These resistant staghorn coral genotypes may explain why pockets of Acropora have been able to survive the WBD epidemic. Understanding disease resistance in these corals may be the critical link to restoring populations of these once dominant corals throughout their range. [ABSTRACT FROM AUTHOR]