Search records. The number of hits returned for each combination of search terms for each database (Web of Science (WoS), SCOPUS and JSTOR) in the two years searches were undertaken. WOS: Phrase Inbreeding terms Search years 2010 2013 "In*breeding coefficient$" "Cost$ of in*breeding" (Depression SAME in*bre*) (Depression SAME fitness) (inbred SAME mating*) NOT (("Quantitative trait loc*")OR(QTL*)) (inbred SAME (offspring OR progeny)) Selfed SAME out* "Optimal outcrossing" OR "Outcrossing distance" "Benefit* of dispersal" "Cost* of dispersal" ("Natal dispersal" AND (inbred OR in*breeding OR heterosis OR self* OR fitness)) (Philopatr* AND (inbred OR in*breeding OR heterosis OR self* OR fitness)) (Heterosis AND in*breeding) 1160 70 3482 422 249 561 237 23 30 80 268 283 9 1365 808 933 899 81 2 12 32 117 389 143 451 131 SCOPUS: Phrase Inbreeding terms Search years 2010 2013 TITLE-ABS-KEY("In*breeding coefficient") TITLE-ABS-KEY("Cost of in*breeding") TITLE-ABS-KEY(Depression W/5 in*bre*) TITLE-ABS-KEY(Depression W/5 fitness) TITLE-ABS-KEY("Genetic load") TITLE-ABS-KEY((inbred W/5 mating*) AND NOT (("Quantitative trait loc*")OR(QTL*))) TITLE-ABS-KEY((inbred W/5 offspring) OR (inbred W/5 progeny)) TITLE-ABS-KEY(Selfed W/5 out*) TITLE-ABS-KEY("Optimal outcrossing" OR "Outcrossing distance") TITLE-ABS-KEY("Benefit* of dispersal") TITLE-ABS-KEY("Cost* of dispersal") TITLE-ABS-KEY(("Natal dispersal" AND (inbred OR in*breeding OR heterosis OR self* OR fitness))) TITLE-ABS-KEY((Philopatr* AND (inbred OR in*breeding OR heterosis OR self* OR fitness))) TITLE-ABS-KEY(Heterosis AND in*breeding) 1325 67 2645 689 790 228 416 30 905 493 190 25 24 75 140 130 37 2 13 31 51 259 96 411 122 JSTOR: 204 62 Phrase Inbreeding terms Search years 2010 2013 "Inbreeding coefficient" OR "inbreeding coefficients" "Cost of inbreeding" OR "costs of inbreeding" "Depression inbred"~5 OR "Depression inbreeding"~5 "Depression fitness"~5 "Genetic load" ("inbred mating"~5 OR "inbred matings"~5) NOT ("Quantitative trait locus" OR "Quantitative trait loci" OR QTL*) 1495 332 3670 638 1427 301 342 91 802 126 198 37 ("inbred offspring"~5 OR "inbred progeny"~5) "Selfed outcross"~5 OR "Selfed outcrossed"~5 OR "Selfed outcrossing"~5 OR "Selfed outcrosser"~5 OR "Selfed outcrossers"~5 OR "Selfed outcrosses"~5 "Optimal outcrossing" OR "Outcrossing distance" 536 711 93 0 373 0 "Benefit of dispersal" OR "Benefits of dispersal" "Cost of dispersal" OR "Costs of dispersal" ("Natal dispersal" AND (inbred OR in*breeding OR heterosis OR self* OR fitness)) (Philopatr* AND (inbred OR in*breeding OR heterosis OR self* OR fitness)) (Heterosis AND (inbreeding OR "in-breeding")) 139 376 1206 44 128 334 2793 542 1356 150 List of articles used in the sensitivity analyses to refine search strategy. 1. Ala-Honkola O, Uddstrom A, Pauli BD, Lindstrom K: Strong inbreeding depression in male mating behaviour in a poeciliid fish. Journal of Evolutionary Biology 2009, 22:1396-1406. 2. Frommen JG, Luz C, Mazzi D, Bakker TCM: Inbreeding depression affects fertilization success and survival but not breeding coloration in threespine sticklebacks. Behaviour 2008, 145:425-441. 3. Mooney EH, McGraw JB: Effects of self-pollination and outcrossing with cultivated plants in small natural populations of American ginseng, Panax quinquefolius (Araliaceae). American Journal of Botany 2007, 94:1677-1687. 4. Fox CW, Scheibly KL, Smith BP, Wallin WG: Inbreeding depression in two seed-feeding beetles, Callosobruchus maculatus and Stator limbatus (Coleoptera : Chrysomelidae). Bulletin of Entomological Research 2007, 97:49-54. 5. Jamieson IG, Tracy LN, Fletcher D, Armstrong DP: Moderate inbreeding depression in a reintroduced population of North Island robins. Animal Conservation 2007, 10:95-102. 6. Mustajarvi K, Siikamaki P, Akerberg A: Inbreeding depression in perennial Lychnis viscaria (Caryophyllaceae): effects of population mating history and nutrient availability. American Journal of Botany 2005, 92:1853-1861. 7. Carr DE, Murphy JF, Eubanks MD: The susceptibility and response of inbred and outbred Mimulus guttatus to infection by Cucumber mosaic virus. Evolutionary Ecology 2003, 17:85-103. Kruuk LEB, Sheldon BC, Merila J: Severe inbreeding depression in collared flycatchers (Ficedula albicollis). Proceedings of the Royal Society of London Series B-Biological Sciences 2002, 269:15811589. Haag CR, Hottinger JW, Riek M, Ebert D: Strong inbreeding depression in a Daphnia metapopulation. Evolution 2002, 56:518-526. 8. 9. 10. Jarne P, Perdieu MA, Pernot AF, Delay B, David P: The influence of self-fertilization and grouping on fitness attributes in the freshwater snail Physa acuta: population and individual inbreeding depression. Journal of Evolutionary Biology 2000, 13:645-655. 11. Alberts SC, Altmann J: Balancing costs and opportunities - dispersal in male baboons. American Naturalist 1995, 145:279-306. 12. Ashman TL: The relative importance of inbreeding and maternal sex in determining progeny fitness in Sidalcea-oregana ssp spicata, a gynodioecious plant. Evolution 1992, 46:1862-1874. 13. Gibbs HL, Grant PR: Inbreeding in Darwin's Medium Ground Finches (Geospiza fortis). Evolution 1989, 43:1273-1284. 14. 15. Hoogland JL: Levels of inbreeding among prairie dogs. American Naturalist 1992, 139:591-602. Madsen T, Stille B, Shine R: Inbreeding depression in an isolated population of adders Vipera berus. Biological Conservation 1996, 75:113-118.