Abstract
Mating system variability is known to exist between and within species, often due to environmental influences. An open question is whether, vice versa, similar environmental conditions entail congruent mating behavior, for example in terms of multiple paternity, in species or populations sharing largely comparable breeding modes. This study employed microsatellite markers to investigate the incidence of multiple paternity in Cyprichromis coloratus and Cyprichromis leptosoma, two sympatric, closely related, mouthbrooding Lake Tanganyika cichlids with similar ecological and behavioral characteristics including the formation of open-water schools. Mouthbrooding females of both species were collected from the same mixed-species breeding school at the same time, minimizing environmental variation during courtship and mating. In C.coloratus, four of 12 broods had more than one sire, with a mean of 1.33 reconstructed sires per brood. C.leptosoma exhibited multiple paternity in 18 of 22 broods, with a mean of 2.59 or 2.86 reconstructed sires per brood according to the programs gerud and colony, respectively. In addition, two broods were found to contain offspring transplanted from another brood. There was no significant difference in brood size between species, but mean sire number did differ significantly. Hence, substantial similarity in reproductive behavior along with shared environmental conditions during courtship and spawning did not lead to equal rates of polyandry or sneaking in the two species.
Highlights
Multiple paternity of broods, clutches, and litters is a taxonomically widespread phenomenon (e.g., Pearse and Avise 2001; Avise et al 2011; Coleman and Jones 2011; Taylor et al 2014)
This study employed microsatellite markers to investigate the incidence of multiple paternity in Cyprichromis coloratus and Cyprichromis leptosoma, two sympatric, closely related, mouthbrooding Lake Tanganyika cichlids with similar ecological and behavioral characteristics including the formation of open-water schools
The sole deviation from Hardy–Weinberg equilibrium occurred at locus Ppun9 in C. coloratus (Table 1), but because observed heterozygosity at this locus was slightly greater than expected heterozygosity (Ho = 0.943 and He = 0.936) and GENEPOP indicated no significant heterozygote deficit (H-W exact test for heterozygote deficiency, P = 0.56), it is unlikely that null alleles would interfere with the paternity analysis
Summary
Clutches, and litters is a taxonomically widespread phenomenon (e.g., Pearse and Avise 2001; Avise et al 2011; Coleman and Jones 2011; Taylor et al 2014). The school from which samples were taken for the genetic parentage analysis in this study comprised both brooding and nonbrooding females as well as mature males of C. leptosoma, C. coloratus and Paracyprichromis brieni, which were segregated by species, sex and breeding status within the school Both C. coloratus and C. leptosoma exhibit male polymorphism with respect to fin coloration, sexual dimorphism (colorful males, drab females) and an unusual mating strategy: males establish three-dimensional territories in the water column several meters above rocky substrate into which they attempt to attract conspecific females (Konings 1998; Takahashi and Hori 2006). Given that variation in mating behavior often correlates with environmental variation, the sharing of a common environment during courtship and spawning predicts congruent patterns of multiple paternity in the two species
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