Article

Diversity of breeding habits in Lamprologine cichlids in Lake Tanganyika

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Abstract

The utilization of microhabitats, mating systems and parental care of 12 cohabiting cichlid fishes in the tribe Lamprologini were investigated at Pemba, NW Lake Tanganyika. From differences in the number of females with whom one male simultaneously mated and the male's contribution to parental care, these fishes were categorized into temporarily haremic species (Altolamprologus compressiceps, Lamprologus lemairii, Neolamprologus fasciatus, Lepidiolamprologus profundicola), permanently haremic speices (Neolamprologus furcifer, N. modestus, N. savoryi) and mono/bigamous species (Lepidiolamprologus attenuatus, L. elongatus, Neolamprologus toae, N. tretocephalus, N. brichardi). Each species has a specific selectivity of breeding sites. The egg size and reproductive output of temporarily haremic species, which correspond to "hole brooders' using rock holes, were large and their sexual dimorphism in size was great compared to the other species. The selectivity of breeding sites of each species may have profoundly influenced the evolution of its reproductive characteristics, mating system and parental care. Coexistence is discussed from the viewpoint of partitioning of breeding sites. -from Author

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... We are not aware of any evidence of spatial sexual segregation in cichlid fish (Barlow 2000) and we assumed that randomly captured specimens were representative of the population. We also complemented our data with SL measures for both sexes obtained from the published literature (e.g., Erlandsson and Ribbink 1997;Gashagaza 1991; see online Supplementary material). SSD estimated from our data was concordant with SSD estimated from data in the literature for 11 of 16 species. ...
... The Lamprologini tribe of Tanganyikan cichlids provides a nice example of how the environment can influence sexual selection and parental investment patterns (Emlen and Oring 1977). Species in this tribe have been categorized as permanently or temporarily haremic, bigamous, or monogamous (Gashagaza 1991). Males generally defend territories with suitable spawning sites (although in L. attenuatus the territories are not clearly defined), however the difference lies in the number of spawning sites within a male's territory. ...
... In some species (e.g., Altolamprologus compressiceps, Neolamprologus fasciatus and N. furcifer) males defend territories with several spawning sites, the mating system is polygynous and males provide no parental care. At the other extreme in monogamous species such as Neolamprlogus toae and N. tretocephalus males defend territories with a single spawning site and the pairbond can be long lasting with some pairs observed to spawn again following independence of their brood (Gashagaza 1991). Within this continuum of variation are L. attenuatus, L. elongatus, and N. brichardi, in which the territories of some males include only one spawning site whereas those of other males include two sites and there is a high prevalence of bigamy. ...
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Despite a massive research effort, our understanding of why, in most vertebrates, males compete for mates and females care for offspring remains incomplete. Two alternative hypotheses have been proposed to explain the direction of causality between parental care and sexual selection. Traditionally, sexual selection has been explained as a consequence of relative parental investment, where the sex investing less will compete for the sex investing more. However, a more recent model suggests that parental care patterns result from sexual selection acting on one sex favoring mating competition and lower parental investment. Using species-level comparative analyses on Tanganyikan cichlid fishes we tested these alternative hypotheses employing a proxy of sexual selection based on mating system, sexual dichromatism, and dimorphism data. First, while controlling for female reproductive investment, we found that species with intense sexual selection were associated with female-only care whereas species with moderate sexual selection were associated with biparental care. Second, using contingency analyses, we found that, contrary to the traditional view, evolutionary changes in parental care type are dependent on the intensity of sexual selection. Hence, our results support the hypothesis that sexual selection determines parental care patterns in Tanganyikan cichlid fishes.
... ARTs are widespread in the Lake Tanganyika substratebrooding cichlid tribe Lamprologini (Sefc 2011), and they have been found in males of the piscivorous cichlid Lamprologus lemairii. This fish is polygynous and displays maternal guarding (Kuwamura 1986;Gashagaza 1991). A territorial male defends a large territory against conspecific males that includes 2-4 separated rock holes (i.e., nests), each of which is defended by a female (Kuwamura 1986;Gashagaza 1991). ...
... This fish is polygynous and displays maternal guarding (Kuwamura 1986;Gashagaza 1991). A territorial male defends a large territory against conspecific males that includes 2-4 separated rock holes (i.e., nests), each of which is defended by a female (Kuwamura 1986;Gashagaza 1991). Intense male-male competition takes place for the holes (Gashagaza 1991), and territorial males are aggressive toward the approach of other males during mating. ...
... A territorial male defends a large territory against conspecific males that includes 2-4 separated rock holes (i.e., nests), each of which is defended by a female (Kuwamura 1986;Gashagaza 1991). Intense male-male competition takes place for the holes (Gashagaza 1991), and territorial males are aggressive toward the approach of other males during mating. In the Uvira (3°36′S, 29°10′E) population, the size distribution of mature males is bimodal (Gashagaza 1991), suggesting that sneakers are present. ...
Article
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To examine how territorial males counter reproductive parasites, we examined the paternity of broods guarded by territorial males using 5 microsatellite loci and factors that determine siring success in a wild population of the Lake Tanganyika cichlid Lamprologus lemairii. Females enter rock holes (nests) and spawn inside, and territorial males release milt over the nest openings. Sneakers attempt to dart into the nests, but territorial males often interrupt the attempt. The body size of territorial males (territorial defense ability) and the size of nest opening (the ability to prevent sneakers from nest intrusions) are predicted to be factors that affect paternity at the premating stage, whereas milt quality traits are factors that affect paternity at the postmating stage. Parentage analyses of 477 offspring revealed that most clutches have few or no cuckolders, and territorial males sired >80% of eggs in 7 of the 10 analyzed clutches. Larger territorial males that spawned in nests with narrower openings had greater siring success. In contrast, none of the milt traits affected the siring success. These suggest that territorial male L. lemairii adopt premating strategies whereby they effectively prevent reproductive parasitism. © 2014 © The American Genetic Association 2014. All rights reserved. For permissions, please e-mail: journals. [email protected] /* */
... In substrate breeders, brood care is carried out by both parents or by the female alone or with the assistance of helpers, and resource distribution and brood care requirements often determine whether or not individuals—usually males—can have more than one mating partner at a time. Harem breeders with little, if any, paternal brood care include the lamprologines Lepidiolamprologus profundicola, L. lemairii, Altolamprologus compressiceps, Neolamprologus furcifer, N. mondabu, and N. modestus [19, 24, 32, 34, 43, 44] . In contrast, exclusive monogamy and biparental guarding were observed in Neolamprologus tretocephalus [24, 43, 44], Boulengerochromis microlepis [45], and Variabilichromis moorii [35, 46, 47]. ...
... Harem breeders with little, if any, paternal brood care include the lamprologines Lepidiolamprologus profundicola, L. lemairii, Altolamprologus compressiceps, Neolamprologus furcifer, N. mondabu, and N. modestus [19, 24, 32, 34, 43, 44] . In contrast, exclusive monogamy and biparental guarding were observed in Neolamprologus tretocephalus [24, 43, 44], Boulengerochromis microlepis [45], and Variabilichromis moorii [35, 46, 47]. Males of several predominantly monogamous lamprologine species (Lepidiolamprologus elongatus, L. attenuatus, and Neolamprologus toae [22, 32, 44, 48]) sometimes breed with two and occasionally more females when adjacent breeding sites are available [24]. ...
... In contrast, exclusive monogamy and biparental guarding were observed in Neolamprologus tretocephalus [24, 43, 44], Boulengerochromis microlepis [45], and Variabilichromis moorii [35, 46, 47]. Males of several predominantly monogamous lamprologine species (Lepidiolamprologus elongatus, L. attenuatus, and Neolamprologus toae [22, 32, 44, 48]) sometimes breed with two and occasionally more females when adjacent breeding sites are available [24]. Parental roles are often divided between the sexes, with the smaller partner, which is in many species the female, remaining closer to the fry and providing direct brood care and the larger partner defending the peripheral parts of the territory (or the adjacent breeding sites) against intruders [19, 35, 43, 46,484950; but see [47]. ...
Article
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Cichlid fishes of Lake Tanganyika display a variety of mating and parental care behaviors, including polygamous and monogamous mouthbrooding and substrate breeding, cooperative breeding, as well as various alternative reproductive tactics such as sneaking and piracy. Moreover, reproductive behaviors sometimes vary within species both in space and in time. Here, I survey reports on mating and parenting behaviors of Lake Tanganyika cichlid species and address the evolution of mating and parental care patterns and sexual dimorphism. Notes on measures of sexual selection intensity and the difficulties of defining mating systems and estimating selection intensities at species level conclude the essay.
... Tanganyikan substrate brooders spawn synchronously during the second quarter of the lunar cycle (Nakai et al., 1990: Rossiter, 1991Gashagaza, 1991), thus enabling parent fishes to protect their eggs and young from predation more effectively on bright nights. However, this explanation cannot be applied to C./eptosoma, broods remaining in the mother's buccal cavity for about I month. ...
... In the study area, L. projhndicola lays eggs on the side of a rock on day 10,4 (• SD, n=ll) of the lunar cycle and protect their brood for two weeks (Watanabe, 2000;Nakai et ah, 1990;Gashagaza, 1991). Juvenile C. lepwsoma use the breeding territory ofL. ...
Article
Lunar reproductive cycles have rarely been documented in freshwater fishes (Schwanck, 1987; Nakai et al., 1990), although common among marine reef fishes (Robertson et al., 1990). Several hypotheses for lunar synchronous spawning have been proposed, based on the effects of the tidal regime on planktonic egg dispersal or hatching from adult habitats (Robertson et al., 1990). However, these hypotheses cannot be applied to fishes inhabiting freshwater bodies, where the lunar cycle never causes tidal fluctuations. However, some authors have proposed several explanations for the adaptive significance of lunar cyclic reproductive activity in freshwater fishes, based on the effects of moonlight. (1) Moonlight provides a cue for pairs to spawn at the same time (Schwanck, 1987). (2) Spawning prior to a full moon enhances the effectiveness of nocturnal parental care of the brood (Schwanck, 1987; Nakai et al., 1990; Rossiter, 1991). (3) Dispersal of young during the fourth quarter of the lunar cycle and the new moon improves the survival of young dispersing under the cover of darkness (Nakai et al., 1990). Cichlid fishes that dominate the coastal fish communities in Lake Tanganyika have two well-developed patterns of parental care, substrate brooding and mouthbrooding (Coulter, 1991; Keenleyside, 1991). In this lake, about one third of the cichlid species are substrate brooders and the remainder mouthbrooders (Poll, 1986). Lunar cyclic spawning has been reported in some substrate brooders, but never in mouthbrooders. However, the spawning activity of a mouthbrooding cichlid, Cyprichromis leptosoma, in fact follows the lunar cycle at the southern end of the lake. I examined whether or not any of the three explanations for lunar spawning synchroneity are applicable to this species, and herein propose an alternative explanation that considers interspecific relationships between juvenile C. leptosoma and substrate brooding species cohabiting the area.
... The ability to swim at high speeds is also associated with brood-guarding patterns. Lamprologini fishes are substrate brooders who deposit, and care for, eggs in nests (Nagoshi, 1983;Gashagaza et al., 1991;Sato, 1994;Rossiter, 1995;Sato and Gashagaza, 1997;Kuwamura, 1997;Sefc, 2011). Females of Ac, Nf and Lc, which all have hard and large scales, close-off the nest entrance with their bodies when brood-predators approach, thus effectively guarding their eggs and small fry with yolk inside nests. ...
... These fry disperse after yolk-absorption; thus, the females do not guard the young from brood predators after they disperse outside of the nests (Kuwamura, 1986(Kuwamura, , 1997Kohda personal observation). In contrast, Le and La deposit eggs in open nests, and young are guarded near the nests for 2 months or more until they are independent (Nagoshi, 1983;Nakai et al., 1990;Nakano and Nagoshi, 1990;Gashagaza, 1991). During the guarding of young located outside of nests, parents attack approaching predators over long distances and at high speed. ...
Article
Many cichlid species in the shallow-shore of Lake Tanganyika suffer damage from attacks by the scale-eater Perissodus microlepis. Many prey fish engage in warning behaviors to this predator. It has been hypothesized that, if prey fish have difficulty employing such behavioral tactics, morphological defenses against scale-eating, such as hard scales, will evolve. The shrimp-eating cichlids, Altolamprologus compressiceps (Ac) and Neolamprologus fasciatus (Nf), exhibit hunting behaviors in which they remain motionless for up to 10 seconds while aiming at prey, when they are vulnerable to scale-eating predators; thus, these fish have likely evolved morphological defenses against "scale-attacks". We tested this hypothesis in Ac and Nf, as well as three other predatory fish, Lamprologus callipterus, Lepidiolamprologus elongatus and Lep. attenuatus, that are not motionless for such a long time. Under natural conditions, Ac and Nf were rarely attacked, while the other three species were attacked frequently. When freshly killed specimens of these five species were displayed underwater in the presence of P. microlepis, Ac was rarely attacked, while Nf and the three other species were attacked frequently. Among the five fish species, the force required to tear off scales was highest for Ac, and this force was negatively correlated with the frequency of attacks on the displayed fish. These results support the hypothesis that the hard scales of Ac function as an anti-scale-attack measure, although it remains unclear why free-swimming Nf were rarely attacked while aiming at prey, despite the fact that the force required to tear off its scales was not large.
... Both sexes of adult N. mondabu (.60 mm standard length [SL]) defend territories against same-sex rivals and food competitors [27]. Males are polygynous and their territories encompass 1-6 female territories [27,28]. Spawning takes place in a burrow that the female digs under a rock within her territory. ...
... Females spawn 140 eggs on average, but the survival rate is considerably low among Lake Tanganyika cichlids [29]. Males pay no regard to their offspring while periodically visiting female territories [27,28]. ...
Article
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Fish demonstrate the greatest variety of parental care strategies within the animal kingdom. Fish parents seldom provision food for offspring, with some exceptions predominantly found in substrate-brooding Central American cichlids and mouth-brooding African cichlids. Here, we provide the first evidence of food provisioning in a substrate-brooding African cichlid Neolamprologus mondabu. This fish is a maternal substrate-brooding cichlid endemic to Lake Tanganyika, and feeds on benthic animals using unique techniques-individuals typically feed on the surface of sandy substrates, but also expose prey by digging up substrates with vigorous wriggling of their body and fins. Young also feed on benthos on the substrate surface, but only using the first technique. We observed that feeding induced by digging accounted for 30% of total feeding bouts in adult females, demonstrating that digging is an important foraging tactic. However, parental females fed less frequently after digging than non-parental females, although both females stayed in pits created by digging for approximately 30 s. Instead, young gathered in the pit and fed intensively, suggesting that parental females provision food for young by means of digging. We tested this hypothesis by comparing the feeding frequency of young before and after digging that was simulated by hand, and observed that young doubled their feeding frequency after the simulated digging. This suggests that parental females engage in digging to uncover food items that are otherwise unavailable to young, and provision food for them at the expense of their own foraging. This behavior was similar to what has been observed in Central American cichlids.
... This number of species corresponds to about 35% of all the cichlid species in the lake (Poll 1986). The morphological, behavioral, and ecological diversity of this group is extremely high (Hori 1983(Hori , 1987(Hori , 1997Nagoshi 1983;Kuwamura 1986;Brichard 1989, p. 325;Barlow 1991;Coulter 1991a;Gashagaza 1991;Keenleyside 1991;Yamaoka 1991, and Poll (1986) was the first to propose assignment of these species to a single taxonomic unit, the Lamprologini. This assignment was supported by a subsequent morphological study by cladistic analysis (Stiassny 1991). ...
Article
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Short interspersed repetitive elements (SINEs) have been shown to be excellent markers of molecular phylogeny, since the integration of a SINE at a particular position in a genome can be considered an unambiguous derived homologous character. In the present study, we isolated a new family of SINEs from cichlids in Lake Tanganyika, whose speciation and diversification have been regarded as prime examples of explosive adaptive radiation. Members of this new SINE family, which we named the AFC family, are about 320 bp in length, and each has a tRNA-related region in its 5' region, as do most of the members of SINE families reported to date. A dot blot hybridization experiment showed that this family is distributed extensively in the genomes of cichlids in Africa, with estimated copy numbers of 2 x 10(3)-2 x 10(4) per haploid genome. Our investigations of the patterns of insertion of members of this family at six orthologous loci demonstrated clearly that four previously identified tribes, namely, the Lamprologini, Ectodini, Tropheini, and Perissodini, each form a monophyletic group. These results provide a basis for the elucidation of the phylogenetic framework of the cichlid fishes in Lake Tanganyika.
... Tactic choice is strictly related to body size (Ota and Kohda 2005). The third species, Lepidiolamprologus elongatus, is a piscivore (Hori et al. 1983), breeding in monogamous pairs (Gashagaza 1991). Pairs vigorously defend eggs and young at their breeding site against conspecific and heterospecific intruders (Ochi and Yanagisawa 1998). ...
Article
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The behaviour of animals towards their mirror image (“mirror test”) is routinely used as a proxy to measure aggression levels, especially in fish. The lack of evidence for visual self-recognition in fish supports this method. However, recent work points towards different hormonal and gene expression responses when fish are exposed either to conspecific opponents or to their mirror image, urging for validation of this widespread method. Here, we test the predictive value of mirror tests in three sympatric cichlid species from Lake Tanganyika: the cooperative breeder Neolamprologus pulcher, the polygamous shell brooder Telmatochromis vittatus and the monogamous, biparental piscivore Lepidiolamprologus elongatus. In particular, we compare differences in restrained and overt aggression levels for individuals of each species when confronted with a mirror or a live conspecific. The three species differed in response to the two contest situations. While in N. pulcher both aggressive responses were correlated between the mirror test and the live opponent fight, there was no such relationship in T. vittatus and L. elongatus. Thus, the mirror test appears to be a suitable surrogate for intraspecific aggression in N. pulcher, while aggression against a mirror image has limited predictive value for intraspecific aggression in the other two species. These results underline the importance of validating the mirror test’s predictive value in a study species before drawing conclusions from mirror tests about aggressiveness under natural, social conditions.
... While it is difficult to assess the number of spawned eggs as well as the spawning interval directly in the field due to the small and cryptic breeding shelters, dissection of adult females revealed small numbers of matured eggs with various stages of immature eggs in the ovaries (HT, unpublished data). Even when considering that N. obscurus is a small cichlid species, such egg numbers are exceptionally low compared to other fishes of the same tribe (range from 10 to > 1500, Yanagisawa 1987;Gashagaza 1991). An explanation for such low egg numbers might be that in this highly philopatric species competition for food, space or hierarchy between subordinates, but also between subordinates and breeders, is assumed to be high (Tanaka et al. 2018b). ...
Article
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In cooperatively breeding animals, individuals other than breeders assist in raising young. While it is generally assumed that such helpers increase the reproductive success of breeders, positive effects can be cryptic and difficult to detect. Furthermore, measuring the effect of helpers in the wild is often difficult because multiple factors such as breeder’s individual quality or experience may affect their reproductive success. Thus far, best examples for fitness benefits of helpers come from a small number of long-term data sets in cooperatively breeding birds and mammals. In contrast, little is known about helpers’ effect on the reproductive success of other cooperatively breeding taxa, e.g., fishes. Here, we investigated the effect of helpers in the cooperatively breeding cichlid Neolamprologus obscurus. We analyzed field data collected during three years to elucidate the effect of helpers on reproductive success of breeders, while considering differences in the quality of breeders and size of their territories. As proxy for reproductive success, we measured the number of juveniles in the respective territory. Our results show that the number of juveniles increased with the number of helpers, while neither breeders’ quality nor the size of the territories had a significant effect. These findings increase our understanding of the beneficial effects of helpers in cooperatively breeding fishes, helping us to understand the evolution of such complex social system in general. Significance statement In cooperatively breeding animals, individuals other than breeders assist in raising young. An increased reproductive success of breeders is the ultimate measure of benefits caused by helpers. However, such relationship is rarely demonstrated in cooperatively breeding fishes. We show that the number of helpers positively correlates with the reproductive success of breeders in the cooperatively breeding cichlid Neolamprologus obscurus. Our results contribute to the understanding of the evolution of cooperative breeding animals.
... However, if ecological conditions change, e.g. if predation pressure is reduced or remating opportunities increase, monogamy can become destabilized and one partner, usually the male, may desert their mate and the young (Barlow 1974, Keenleyside 1983, Keenleyside 1985, Townshend & Wootton 1985, Wisenden 1994. A number of biparental species have been reported to be facultatively polygamous (Kuwamura 1986, Gashagaza 1991, Wisenden 1994, presumably made possible by the division of labour between the parents. In general, females tend to provide direct brood care, guarding and tending the fertilized eggs and newly hatched young, while males defend the periphery of the territory (Barlow 1974, Smith-Grayton & Keenleyside 1978, Dupuis & Keenleyside 1982, Mrowka 1982, Itzkowitz 1984, Itzkowitz 1985, Townshend &Wootton 1985, Rogers 1988, Lavery & Keenleyside 1990, Barlow 1991, Lavery & Reebs 1994, Annett et al. 1999. ...
Article
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One of the most widely accepted explanations for monogamy is the need for biparental care. However, the occurrence of monogamy combined with biparental care is extremely rare in oral incubating (mouthbrooding) cichlid fishes. Few studies have been performed on cichlid species that exhibit this behaviour, and therefore the ecological factors that favour monogamy in these cases remain obscure. Here we present new information on the natural history and reproductive biology of Eretmodus cyanostictus (Boulenger 1898), a monogamous biparental mouthbrooder from Lake Tanganyika. The populations studied consisted of territorial pairs and a male-biased non-territorial population of smaller 'floater' individuals. We present the first detailed description of spawning in this species, show that breeding does not appear to be synchronised within the population, and provide evidence that parental care is costly. We discuss the implications of this information for our understanding of monogamy.
... Indeed, in substrate guarding Tanganyikan cichlids, the availability of suitable spawning sites within a male's territory determines the degree of polygyny. Polygynous males defend territories where several females lay their eggs and care for the brood alone, whereas monogamous males defend territories with a single spawning female and provide some parental care (Gashagaza, 1991). Such interactions between ecology and sexual selection might explain why mating system presented higher disparity indices, but not stronger selection, under an OU model, than did naturally selected traits. ...
Article
Theory suggests that sexual traits evolve faster than ecological characters. However, characteristics of a species niche may also influence evolution of sexual traits. Hence, a pending question is whether ecological characters and sexual traits present similar tempo and mode of evolution during periods of rapid ecological divergence, such as adaptive radiation. Here, we use recently developed phylogenetic comparative methods to analyse the temporal dynamics of evolution for ecological and sexual traits in Tanganyikan cichlids. Our results indicate that whereas disparity in ecological characters was concentrated early in the radiation, disparity in sexual traits remained high throughout the radiation. Thus, closely related Tanganyikan cichlids presented higher disparity in sexual traits than ecological characters. Sexual traits were also under stronger selection than ecological characters. In sum, our results suggest that ecological characters and sexual traits present distinct evolutionary patterns, and that sexual traits can evolve faster than ecological characters, even during adaptive radiation.
... Twelve feeding guilds were present, and resource partitioning within guilds was accomplished via different foraging methods. Keen competition takes place for breeding sites, which are a critical resource (Gashagaza 1991). ...
Chapter
THE STRUCTURE OF LAKE FISH COMMUNITIESINTERACTIONS WITHIN FISH COMMUNITIESFISH COMMUNITIES AND ENVIRONMENTAL CHANGEFISH PRODUCTION AND FISHERIES YIELD
... Only females provide parental care for their broods for c. 70 days (Nagoshi, 1985;Takemon & Nakanishi, 1998). Males encompass one to six female territories in their territories, and hold harems (Gashagaza, 1991). ...
Article
In species with alternative reproductive tactics (ARTs), males employing different tactics usually have different appearance. The clearest difference is body size: bourgeois males that monopolize access to females are larger than sneaker males that steal fertilizations from them. Sneakers are also known to be often dull in colour compared with bourgeois males and rather resemble females. However, this typical colour pattern is unlikely in the Lake Tanganyika cichlid Neolamprologus mondabu: we observed sneaking by two distinctive colour morphs, namely, black (which is apparently conspicuous against the background) and white (which is apparently background-matching). Because breeding females are black, this observation indicates that one type of sneakers contrasts female appearance. In this study, we conducted field studies to determine the expression of body colour in relation to ARTs in this fish. Body colour was dependent on size, but not sex and maturation, with black individuals being larger than white ones. Together with the presence of intermediate grey colour expressed by intermediate-sized individuals, this fish could ontogenetically changes their body colour from white to black. Both sexes of black individuals occupied feeding territories, but white individuals were non-territorial, indicating that the black body signals the possession of a feeding territory. Sexually active females were invariably black, whereas sexually active males were both black and white in colour. Few of the largest black males held harems, which included several female territories, whereas the remaining males were bachelors with no female territories. These bachelor males invested more in testes than harem males, suggesting that bachelors employ sneaking tactics, which is corroborated by our sneaking observations. To our knowledge, this is the first study showing that sneakers are entirely dissimilar to females in appearance. Herein, we discuss why sneakers are dichromatic in relation to their life histories.
... Two factors which are unique in social and reproductive features in J. ornatus may be relevant to this question. First, although they show bi-parental care, the cost of parental care is likely to be lower than other bi-parental cichlids; J. ornatus breed in rock crevices, and their fry is the benthic type, which is considered to be more easily defended by parents from fry predators than the vertical type distribution of fry (Kuwamura, 1986b; Yanagisawa, 1987; Gashagaza, 1991). Second, the large fish of both sexes (>80 mm TL) often becomes the harem master and may obtain greater reproductive success thereafter (Awata, unpubl. ...
Article
Parental roles and the amount of care in bi-parental fish have been assumed to be determined by sex. We studied the parental behaviour in a substrate brooding cichlid Julidochromis ornatus (40-90 mm in total length) in which both parents participate in care of eggs and young. In the study population, ca 80% of paired females were larger than their partners and pairs mated assortatively for size. Males spent more time with their offspring in female-largest pairs, whereas the opposite was found for male-largest pairs. These differences in the amount of care were more conspicuous when differences in body size were greater, whereas similar sized pairs shared parental tasks. These results suggest that the amount of parental care is largely affected by the relative size within pairs independent of sex in J. ornatus. However, the frequencies of defensive behaviours were not different in both female-largest and male-largest pairs. This indicates that parental roles would not completely change as the change of the body size difference within pairs. The larger parents were socially dominant over the partners regardless of sex, and observations of aggressive behaviours within pairs suggest that the larger fish are likely to make the partners perform parental care. Higher frequencies of aggressive encounters were observed in the similar-sized pairs than in the different-sized ones. Higher costs associated with frequent aggressive behaviours in the similar-sized pairs may be related to their small brood size, and may be partly responsible for the size-assortative mating with sexual size difference in this fish. 1) Corresponding author's e-mail address: awata@sci.osaka-cu.ac.jp 2) We are grateful to the late Leonard M. Mwape, Reuben Shapola and the staff of Lake Tanganyika Research Unit for assistance in the field. We also wish to thank Murray Itzkowitz, Karen D. Crow and an anonymous referee for their helpful comments that greatly improved the manuscript.
... On the contrary, a species' ecological niche can influence the mating system and secondary sexual signals which may develop [53]. The Lamprologini tribe of Tanganyikan cichlids provides a nice example of this since species have been categorized as permanently or temporarily haremic, bigamous, or monogamous and the mating system and degree of sexual size dimorphism appear to be related to the number of suitable spawning sites within a male's territory [54]. However, we did not find any signal for sexual selection leading to sexual size dimorphism in cerebellum volume, suggesting that the effect is similar in both sexes. ...
Article
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Analyses of the macroevolutionary correlates of brain structure volumes allow pinpointing of selective pressures influencing specific structures. Here we use a multiple regression framework, including phylogenetic information, to analyze brain structure evolution in 43 Tanganyikan cichlid species. We analyzed the effect of ecological and sexually selected traits for species averages, the effect of ecological traits for each sex separately and the influence of sexual selection on structure dimorphism. Our results indicate that both ecological and sexually selected traits have influenced brain structure evolution. The patterns observed in males and females generally followed those observed at the species level. Interestingly, our results suggest that strong sexual selection is associated with reduced structure volumes, since all correlations between sexually selected traits and structure volumes were negative and the only statistically significant association between sexual selection and structure dimorphism was also negative. Finally, we previously found that monoparental female care was associated with increased brain size. However, here cerebellum and hypothalamus volumes, after controlling for brain size, associated negatively with female-only care. Thus, in accord with the mosaic model of brain evolution, brain structure volumes may not respond proportionately to changes in brain size. Indeed selection favoring larger brains can simultaneously lead to a reduction in relative structure volumes.
... Male parental care is usually limited to guarding the offspring during its free-swimming stage. This marked division of labor has been described for several substrate-brooding cichlids (Baerends and Baerends Van Roon 1950;Baerends 1984;Kuwamura 1986;Gashagaza 199 1; reviewed in Barlow 199 1;Keenleyside 199 1;Stiassny and Gestner 1992). While most cichlid lineages are relatively uniform in terms of their breeding behavior, the Lamprologini evolved a high diversity from ancestral to highly derived patterns of parental care such as breeding in gastropod shells, polygyny, or the recruitment of the offspring as helpers for parental care (table 3 ) . ...
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Lake Tanganyika harbors the oldest, morphologically and behaviorally most diverse flock of cichlid species. While the cichlids in Lakes Malawi and Victoria breed their eggs exclusively by buccal incubation (termed "mouthbrooding"), the Tanganyikan cichlid fauna comprise mouthbrooding and substrate-spawning lineages (fish spawn on rocks, and never orally incubate eggs or wrigglers). The substrate-spawning tribe Lamprologini appears to occupy a key position that might allow one to elucidate the origin of the Tanganyika flock, because five riverine (therefore nonendemic) species from the Zaire River system have been assigned to this tribe, in addition to the lake's endemic species, which make up almost 50% of all 171 species known from this lake (Poll 1986). From 16 species (18 individuals) of the tribe Lamprologini, a 402-bp segment of the mitochondrial cytochrome b gene was sequenced, and, from 25 lamprologine species (35 individuals), sequences from the mitochondrial control region were obtained. To place the Lamprologini into a larger phylogenetic framework, orthologous sequences were obtained from eight nonlamprologine Tanganyikan cichlid species (13 individuals). The Lamprologini are monophyletic, and a clade of six Tanganyikan lineages of mouthbrooders, representing five tribes (Poll 1986), appears to be their sister group. Comparisons of sequence divergences of the control region indicate that the Lamprologini may be older than the endemic Tanganyikan tribe Ectodini, and short basal branches might suggest a rapid formation of lineages at an early stage of the Tanganyika radiation. It is interesting that three analyzed riverine members of the tribe form a monophyletic group; however, they are not the most ancestral branch of the Lamprologini. This might indicate that they are derived from an endemic lamprologine ancestor that left Lake Tanganyika by entering the Zaire River system. These riverine species may not have seeded the Tanganyikan radiation, as currently thought, but may have recently recolonized the river after a long period of isolation, as soon as the lake was connected to the Zaire River again about 2 Mya. Neolamprologus moorii, endemic to Lake Tanganyika, appears to represent the most basal clade of the Lamprologini. Complex breeding behavior, involving the usage of gastropod shells and associated with dwarfism, is likely to have evolved in parallel in several lineages among the Lamprologini. The tribe Lamprologini may be in need of revision, since several genera appear to be polyphyletic.
... Information on clutch size, egg size and body size were collected for as many of the 1400 species within the 222 genera of cichlids as possible. These data originated from Axelrod & Burgess (1988), Brichard (1989), Cichocki (1976), Conkel (1993), Gashagaza (1991), Keenleyside (1991), Kawanabe et al. (1997), Konings (1990), Kullander & Nijseen (1989), Linke & Staeck (1994, 1996a, Loiselle (1985), Lowe-McConnell (1955, 1959, Richter (1989), Trewavas et al. (1972), Trewavas (1983) and Stawikowski & Werner (1998). Most data on egg sizes originated from Coleman (2002) within Fishbase 2002 (Froese & Pauly, 2002). ...
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The negative relationship between offspring number and offspring size provides a classic example of the role of trade-offs in life history theory. However, the evolutionary transitions in egg size and clutch size that have produced this negative relationship are still largely unknown. Since body size may affect both of these traits, it would be helpful to understand how evolutionary changes in body size may have facilitated or constrained shifts in clutch and egg size. By using comparative methods with a database of life histories and a phylogeny of 222 genera of cichlid fishes, we investigated the order of evolutionary transitions in these traits in relation to each other. We found that the ancestral large-bodied cichlids first increased egg size, followed by a decrease in both body size and clutch size resulting in the common current combination of a small-bodied cichlid with a small clutch of large eggs. Furthermore, lineages that deviated from the negative relationship between clutch and egg size underwent different transitions in these traits according to their body size (large bodied genera have moved towards the large clutch/small egg end of the continuum and small bodied genera towards the small clutch/large egg end of the continuum) to reach the negative relationship between clutch size and egg size. Our results show that body size is highly important in shaping the negative relationship between clutch size and egg size.
... For 25 species we found data on all four key characters. These data originated from Axelrod & Burgess (1988), Brichard (1989), Cichocki (1976, Conkel (1993), Gashagaza (1991), Keenleyside (1991), Kawanabe et al. (1997), Konings (1990), Kullander & Nijseen (1989), Linke & Staeck (1994, 1996a, Loiselle (1985), Lowe- McConnell (1955McConnell ( , 1959McConnell ( , 1969, Richter (1989), Trewavas et al. (1972), Trewavas (1983), Stawikowski & Werner (1998). Most data on egg sizes originated from Coleman (2002) within Fishbase 2002 (Froese & Pauly, 2002). ...
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Empirical links between egg size and duration of parental care in fishes have generated a considerable amount of theory concerning life history evolution. However, to date, this link has not been investigated in relation to other important life-history traits such as clutch size and body size, or while controlling for shared ancestry between species. We provide the first phylogenetically based tests using a database with information on egg size, clutch size, body size and care duration in cichlid fishes (Cichlidae). Multiple regression analyses, based on independent contrasts on both the species and the genus level, showed that clutch size is the variable most closely related to duration of care. This pattern appeared to be driven by post-hatch care relationships. Our results show that, contrary to expectation, there is no positive link between egg size and care duration in Cichlidae. Instead, greater reproductive output through increased clutch size investment appears to have coevolved with greater care of offspring. We suggest that re-evaluation of the generality of current models of the evolution of egg size under parental care in fishes is needed.
... Moreover, a number of studies have investigated the choice of spawning sites in relation to substrate types (Gashagaza, 1991;Leman, 1993) which may include factors such as dissolved oxygen concentration (Peterson and Quinn, 1996) and supply of ground water (Curry and Noakes, 1995). Many of these studies have speculated that selection of certain spawning sites results in higher reproductive success, though few have substantiated this with evidence. ...
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We collected schools of young, guarded by parents, of six common cichlid species to investigate the frequency and origin of interspecific brood-mixing. The main host species were a piscivore Lepidiolamprologus elongatus and a scale-eater Perissodus microlepis; more than half of their schools included heterospecific young, accounting for 20–40% of the total young. Most of the foreign young belonged to four biparental mouth-brooders whose parents have a habit of carrying their young in their mouths. Many of these young were smaller than the largest young brooded by their own parents. We concluded that adoption of young before independence results from farming-out, a behavior by which parents actively transfer their young to foster parents.
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Cichlid fishes (Perciformes: Teleostei) found in the lakes of Africa have served as model systems for the study of evolution. The enormous number of species (1000 in Lake Malawi alone), the great diversity of trophic adaptations and behaviors, and the extreme rapidity of their divergence (<50,000 y for some faunas) single out these organisms as examples of evolution in progress. Because these fishes are confined to discrete lacustrine environments and their origination is bounded by geological features, these groups provide models with which to study evolution. We review theoretical studies and empirical research on the cichlid fau-nas of Africa to provide a synthetic overview of current knowledge of the evolu-tionary processes at work in this group. This view provides the critical information needed to formulate and test hypotheses that may permit discrimination among the diverse theories and models that have been advanced to explain the evolution of these fishes.
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Interspecific competition for spawning sites between two gobiid fishes, Bathygobius fuscus and Eviota abax, was studied on a rocky shore. Large males (LM: 55–80?mm in standard length: SL) and small males (SM: 34–52?mm SL) of B. fuscus acted as nest holders and sneakers, respectively, in the early spawning season (July). The sympatric male E. abax (22–33?mm SL) was smaller than SM B. fuscus, and synchronically used rocky holes much smaller than those of LM B. fuscus. In this season, aggressions between the two species were rarely observed. In late season (August), as the number of the LM decreased, the SM converted their tactics to nest holding, occupying nests of a sizes similar to those of E. abax. Eviota abax males were dispossessed by SM and shifted their nest sites to cavities between cobbles and sandy bottom, which might be poorer nest sites than rocky holes.
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The zooplanktivorous cichlid Microdontochromis sp. formed large stationary schools in midwater consisting of mouthbrooding and nonbrooding individuals. Early young smaller than 6.0 mm in standard length were mouthbrooded solely by females, but large young, up to 17.4 mm, were mouthbrooded by both females and males. Mouthbrooding fish took food as actively as nonbrooding fish to nourish the young and themselves. Eggs were 1.9 mm in maximum diameter, among the smallest known for mouthbrooding cichlid fishes. Young which ate food within the parent's buccal cavity showed a 10-fold increase in dry weight during the mouthbrooding period. Data suggested that parents finally farmed out their young into broods of other cichlid fishes.
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This chapter focuses on the cichlid fauna of Lake Tanganyika, the least studied of the African Great Lakes. It places particular emphasis on the faunas of the rocky shore habitats, and explores the great species diversity that may have arisen. The chapter describes the evolutionary scenarios within the lake and the biology of these fishes. Several of the more parsimonious explanations as to how the extant species diversity is maintained are considered, and examples of resource partitioning among coexisting species along a variety of resources axes, the most likely mechanism of coexistence, are given. It also illustrates several examples of the diversity of feeding and breeding habits seen both within groups and within species. Moreover, the cichlids of Lake Tanganyika offer splendid, perhaps unique, opportunities for studies of ecology, behavior and evolution, yet there is a paucity of quantitative information concerning the ecology and evolution of its species flocks, such that our present level of knowledge is insufficient on which to form comprehensive theories regarding factors structuring these communities.
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