Table S1. F2 Spawning decisions of F2 hybrid femalesTable S1 contains a summary of the spawning decisions of all F2 hybrid females, including their IDs, brood numbers and fathers. 1-32 is the experimental round and each round may include more than one spawning decision per female. 0 = spawning decision with P. sp. "pundamilia-like" 1 = spawning decision with P. sp. "nyererei-like" out = female isolated in a tank with a male of the non-preferred species in = female re-introduced into the experiment out = female isolated in a tank with a male of the non-preferred species in = female re-inroduced into the experimentSvensson_et_al_Table_S1_CVS.csv

 Table S2. Spawning decisions of wild type females and F1 femalesTable S2 contains a summary of the spawning decisions of all wild type females and F1 hybrid females 1-32 is the experimental round and each round may include more than one spawning decision per female. Species: p = P. sp. "pundamilia like" n = P. sp. "nyererei-like" pn = F1 hybrid between female P. sp. "pundamilia like" and male P. sp. "nyererei-like" np = F1 hybrid between female P. sp. "nyererei-like" and male P. sp. "pundamilia like" 0 = spawning decision with P. sp. "pundamilia-like" 1 = spawning decision with P. sp. "nyererei-like"Svensson_et_al_Table_S2_CVS.csv

 Table S3. Males used in the spawning experiment: Microsatellite genotypes and experimental roundMales used in the spawning experiment. ID is the identification code. IDs starting with m were lab bred males. All others males were wild caught. Spec is the species. 1&2-30-32 are the experimental rounds. The numbers are the experimental rounds and the positions of the compartments. 11 is the first round and the first compartment, 12 is the first round and the second compartment etc. 21 is the second round and the first compartment, 22 is the second round and the second compartment etc. Ppun7-Ppun32 are the microsatellite genotypes of the males (in bp)Svensson_et_al_Table_S3_CVS.csv

 Table S4. Raw data and paternal analysesTable S4 includes microsatellite raw data of the offspring of the F2 females (q1-35 and 1-286), the wild type females (p and n) and the F1 hybrid females (pn and np), as well as the paternity analyses. ID (Blank): The ID of the female used in Table S1-2, Brood No: The numer of the brood, Prefix: The prefix in the PIT-tag number, Suffix: The suffix in the PIT-tag number, SL (mm): Standard length (mm), TL (mm): Total lenght (mm), Weight (g), No fry: Number of fry in the brood, Date stripped, No broods, Experimental round: Experimental round in Table S1-2, (Blank), Mother: Result of maternal analyses (same as ID if left blank), Father: Result of the paternity analyses, Ppun7a: Microsatellite lengt in base pairs (bp), Ppun7b: Microsatellite lengt in base pairs (bp), Ppun5a: Microsatellite lengt in base pairs (bp), Ppun5b: Microsatellite lengt in base pairs (bp), Ppun21a: Microsatellite lengt in base pairs (bp), Ppun21b: Microsatellite lengt in base pairs (bp), Ppun17a: Microsatellite lengt in base pairs (bp), Ppun17b: Microsatellite lengt in base pairs (bp), Ppun32a: Microsatellite lengt in base pairs (bp), Ppun32b: Microsatellite lengt in base pairs (bp).Svensson_et_al_Table_S4.xlsx

The genetic architecture of mate preferences is likely to affect significant evolutionary processes, including speciation and hybridization. Here, we investigate laboratory hybrids between a pair of sympatric Lake Victoria cichlid fish species that appear to have recently evolved from a hybrid population between similar predecessor species. The species demonstrate strong assortative mating in the laboratory, associated with divergent male breeding coloration (red dorsum versus blue). We show in a common garden experiment, using DNA-based paternity testing, that the strong female mate preferences among males of the two species are fully recovered in a large fraction of their F2 hybrid generation. Individual hybrid females often demonstrated consistent preferences in multiple mate choice trials (more than or equal to five) across a year or more. This result suggests that female mate preference is influenced by relatively few major genes or genomic regions. These preferences were not changed by experience of a successful spawning event with a male of the non-preferred species in a no-choice single-male trial. We found no evidence for imprinting in the F2 hybrids, although the F1 hybrid females may have been imprinted on their mothers. We discuss this nearly Mendelian inheritance of consistent innate mate preferences in the context of speciation theory.