Intragenus F1-hybrids of African weakly electric fish (Mormyridae: Campylomormyrus tamandua ♂ × C. compressirostris ♀) are fertile

• Published in: Journal of Comparative Physiology 2020-07, Vol.206 (4), p.571-585
• Main Authors: Korniienko, Yevheniia, Nguyen, Linh, Baumgartner, Stephanie, Vater, Marianne, Tiedemann, Ralph, Kirschbaum, Frank
• Format: Article
• Language: English
• Subjects: Animal Physiology; Animals; Biomedical and Life Sciences; Breeding; Campylomormyrus tamandua; Eggs; Electric Fish - classification; Electric Fish - physiology; Electric instruments; Electric Organ - cytology; Electric Organ - physiology; Electric organs; Embryogenesis; Embryonic growth stage; Female; Fertility; Fertilization; Fish; Fish eggs; Hatching; Hybridization; Hybridization, Genetic; Hybrids; Larvae; Life Sciences; Male; Mormyridae; Neurosciences; Organs; Original Paper; Sexual maturity; Speciation; Survival; Zoology
• ISSN: 0340-7594; 1432-1351
• DOI: 10.1007/s00359-020-01425-7

Hybridization is widespread in fish and constitutes an important mechanism in fish speciation. There is, however, little knowledge about hybridization in mormyrids. F1-interspecies hybrids between Campylomormyrus tamandua ♂  ×  C. compressirostris ♀ were investigated concerning: (1) fertility; (2) survival of F2-fish and (3) new gene combinations in the F2-generation concerning the structure of the electric organ and features of the electric organ discharge. These F1-hybrids achieved sexual maturity at about 12–13.5 cm total length. A breeding group comprising six males and 13 females spawned 28 times naturally proving these F1-fish to be fertile. On average 228 eggs were spawned, the average fertilization rate was 47.8%. Eggs started to hatch 70–72 h after fertilization, average hatching rate was 95.6%. Average mortality rate during embryonic development amounted to 2.3%. Average malformation rate during the free embryonic stage was 27.7%. Exogenous feeding started on day 11. In total, we raised 353 normally developed larvae all of which died consecutively, the oldest specimen reaching an age of 5 months. During survival, the activities of the larval and adult electric organs were recorded and the structure of the adult electric organ was investigated histologically.