Mating system variability in a mouthbrooding cichlid fish from a tropical lake

Abstract

Intraspecific variability in mating behaviour and disparities between social and reproductive behaviour add complexity to the description of animal mating systems. A previously published field study on a population of the maternally mouthbrooding cichlid fish Ctenochromis horei in the north of Lake Tanganyika suggested mate monopolization by the most dominant male. In the present study, genetic reconstructions of paternity in a population in the south of the lake provided no evidence for male mate monopolization, as none of the inferred sires had offspring in more than one brood. The ability to reconstruct sire genotypes from offspring alleles was confirmed by computer simulations. Multiple paternity occurred in several broods and was significantly more frequent in the sample taken in the rainy season than in the dry season sample (100% of broods vs. 14%, respectively; P = 0.005). The data suggest geographical and temporal variation in the mating behaviour of C. horei despite its continuous year-round reproduction, invariable brood care behaviour and habitat-specific distribution in the relatively constant and confined environment of a tropical lake. Moreover, our data show that inferences on the distribution of male reproductive success, if based on each geographical or temporal data set alone, would fail to describe the potential for sexual selection in this species.

Same school, different conduct: rates of multiple paternity vary within a mixed‐species breeding school of semi‐pelagic cichlid fish (Cyprichromisspp.)

“…2007; Mobley and Jones 2009; Sefc et al. 2009; Candolin and Vlieger 2013). However, the broods analyzed in this study were collected at the same time from the same school, and as both Cyprichromis species appear to synchronize their spawning with the lunar cycle (Watanabe 2000; Takahashi and Hori 2006), the ecological differences generally thought to produce such variability were not present.…”

“…The search was limited to reconstructed sires that had contributed at least six offspring to a brood because smaller offspring numbers are not sufficiently informative about the sire's genotype (Sefc et al. 2009). The presence of skewed paternal contributions in the colony results for each brood was assessed using skew calculator 2003 (https://www.eeb.ucla.edu/Faculty/Nonacs/PI.html) to calculate the binomial skew index B (Nonacs 2000) and its associated P ‐value using 10,000 simulations.…”

“…2012), and intraspecific geographic and temporal variation in reproductive behavior was inferred from field observations and genetic parentage (Rossiter 1995; Matsumoto and Kohda 1998; Sefc et al. 2009). The two mouthbrooding Cyprichromis species addressed in this study occur in multispecies schools of up to several thousand individuals, synchronize spawning by the lunar cycle (Watanabe 2000; Takahashi and Hori 2006) and therefore experience similar environmental conditions during courtship and spawning.…”

Mating and Parental Care in Lake Tanganyika's Cichlids

“…Mating generally occurs in the males' territories, which can be arranged in expanded leks, and polygamy is the norm in these species. Indeed, multiple paternity was demonstrated by genetic data in some of the broods of Ctenochromis horei with up to five sires per brood [85] and Simochromis pleurospilus with one or two sires per brood [86]. Multiple paternity can result from successful alternative male reproductive behavior such as sneaking or from deliberate polyandry when females visit several males for spawning [20].…”

“…Intrusions by neighboring territory owners and attempts of parasitic spawning may also cause a female to interrupt spawning with her current mate and perhaps later resume spawning with a different male, as observed in, for example, Gnathochromis pfefferi [92] and Ophthalmotilapia ventralis [93]. In contrast, females of another open-water spawner, Cyprichromis microlepidotus , were observed to spawn their entire clutch with one male [87], and several of the genetically analyzed broods of Ctenochromis horei (43%) [85] and Simochromis pleurospilus (65%) [86] were in fact sired by a single male each. Only one or two broods have so far been analyzed with respect to genetic relatedness in other polygamous maternal mouthbrooders (the Tropheini species Simochromis diagramma , Petrochromis fasciolatus , P. orthognathus, and Gnathochromis pfefferi ).…”