LB 20-203 - Intraspecific variation in mating systems in the convict cichlid (Amatitlania nigrofasciata)

Background/Question/Methods:

In animals, there are several mating systems and each mating system can increase reproductive success depending on selection pressures. Choosing the most successful mating system increases fitness; thus, acts as a driving force of evolution. The evolution of monogamy and biparental care occurs when there is high predation pressure on the offspring. Although there are multiple mating systems observed across species, it is uncommon to observe intraspecific variation in mating systems. For the last 50 years, convict cichlid fish have been used as a model species for monogamy. Recently, it has been suggested that a part of the population is socially monogamous. However, no research has compared the genetics of parents to their offspring to determine if one or both sexes are engaging in extra-pair mating. We hypothesize that any mixed-heritage broods would be the result of males having the extra pair matings. In 2018, morphometrics, behavioral data, and tissue samples were collected from 35 mated pairs and their brood found in Rio Cabuyo at Lomas Barbudal Biological Reserve, Costa Rica. Microsatellite fragment analysis was performed in four different loci to determine the paternity/maternity of each offspring.

Results/Conclusions:

Early results show that 87.5% of families had social monogamy, and 12.5% exhibited genetic monogamy. Surprisingly, 59.4% of the families exhibited adoption and only 9.4% of the families analyzed had both genetic monogamy and no adoption. Female-only extra-pair copulation was observed in 5 pairs, male-only extra-pair copulation was observed in 2 pairs, and both male and female extra-pair copulation was observed in 21 pairs. These results are preliminary but demonstrate social monogamy and adoption occur in convict cichlids. Furthermore, our hypothesis that males would be the ones exhibiting extra-pair matings is rejected because there was evidence that both males and females exhibit extra-pair matings. Further research will need to be done to illuminate the causes behind adoption and social monogamy.