Female mouthbrooders in control of pre- and postmating sexual selection

Abstract

The fertilization mode determines which sex has greater control over the offspring's sires. With internal fertilization, females can strongly influence the chances of different males' ejaculates to fertilize their eggs by the postmating sexual selection process referred to as cryptic female choice. In contrast, when fertilization is external and multiple males compete in this process, the outcome of pre-and postmating sexual selection is largely determined by the competitive quality of males and their sperm. Intermediate modes of fertilization as found in mouthbrooding fishes might allow for a greater maternal influence on her offspring's sire. Here, we show that in the maternal mouthbrooder Ophthalmotilapia ventralis, females collect sperm from different males in their mouth, and males can successfully fertilize eggs even if the female did not lay eggs with them. In the field, 25 of 30 clutches had multiple sires, and the fertilization success was significantly biased toward particular males in most clutches. A mate choice experiment revealed that females prefer to spawn with males possessing strongly elongated pelvic fins, a conspicuous secondary sexual character of males in this cichlid. Additionally, the body length of males partly explained their success in sperm competition within the females' mouth, a factor without apparent influence on female choice of partners with which to lay eggs. Hence, successful sires are determined by a 2-step process that is largely under female control; females select which males to spawn with and from which males they collect additional ejaculates for the subsequent sperm competition in their mouth.

Bower‐building behaviour is associated with increased sperm longevity in Tanganyikan cichlids

“…Even in the NBBE species O. ventralis , which is closely related to BBE species within the tribe Ectodini, we observed female nuzzling behaviour to the yellow tips of the male's pelvic fins (Fig. S3; Haesler et al ., ). This behaviour supports the conclusion of a previous study that fertilization likely occurs in the females’ mouth in this species (Haesler et al ., ).…”

“…S3; Haesler et al ., ). This behaviour supports the conclusion of a previous study that fertilization likely occurs in the females’ mouth in this species (Haesler et al ., ).…”

“…We categorized 28 mouth‐brooding cichlids into four groups according to whether they built bowers or had egg‐spots or egg‐dummies (Table ): (1) bower‐building species with egg‐spots or egg‐dummies (BBE, two species), (2) bower‐building species with no egg‐spots or egg‐dummies (BBNE, seven species), (3) non‐bower‐building species with egg‐spots (NBBE, 11 species) and (4) non‐bower‐building species with no egg‐spots (NBBNE, eight species). Prior reports have shown that these cichlids have different mating systems (Table ; Ochi, ; Egger et al ., ; Schaedelin & Taborsky, ; Haesler et al ., ; Immler & Taborsky, ; Sefc et al ., ; Haesler et al ., ; Sefc et al ., ), suggesting that sperm competition levels also differ among mouth‐brooders with different mating systems.…”

“… 1: Kuwamura, ; 2: Schaedelin & Taborsky, ; 3: Immler & Taborsky, ; 4: Haesler et al ., ; 5: Haesler et al ., ; 6: Sefc et al ., ; 7: Egger et al ., ; 8: Sefc et al ., ; 9: Sefc et al ., ; 10: Ochi, . …”

“…Males have yellow egg-dummies on their pelvic fins, which may be used to induce the transfer of sperm to the female's mouth (Immler & Taborsky, 2009). Therefore, fertilization is likely to occur when females take the eggs into their buccal cavity (Haesler et al, 2011).…”