Ecological studies on crater lakes in West Cameroon Fishes of Barombi Mbo

Trewavas, Ethelwynn; Green, J.; Corbet, Sarah A.

doi:10.1111/j.1469-7998.1972.tb01722.x

Cited by 84 publications

(101 citation statements)

References 17 publications

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“…This gene is otherwise known to be used exclusively during the larval period in Nile tilapia (Spady et al, ). Similarly, we detected expression of the UV‐sensitive SWS1 opsin (expressed in larvae of Nile tilapia; Spady et al, ) in one species, S. steinbachi , an algae/debris feeder and the most herbivorous species from the lake (Baldo et al, ; Trewavas et al, ; and personal observation of higher plant feeding). The link between herbivory and SWS1 expression is in agreement with the observations of O'Quin et al () in Malawi cichlids, where algae scrapers (together with zooplanktivores) have increased expression levels of SWS1.…”

Section: Discussionmentioning

confidence: 56%

“…Tissue samples were collected in crater lake Barombi Mbo (coordinate: 9°22′E, 4°38′N; Trewavas et al, ), South‐West Cameroon, between 2013 and 2018 (research permit numbers: 0000047,49/MINRESI/B00/C00/C10/nye, 0000116,117/MINRESI/B00/C00/C10/C14, 000002‐3/MINRESI/B00/C00/C10/C11, 0000032,48‐50/MINRESI/B00/C00/C10/C12). Between 8 and 16 individuals per each of all 11 cichlid species were collected using gill nets and selective capturing by snorkelling in the shallow‐water zone, and with gill nets and minnow traps for the deeper zone.…”

Section: Methodsmentioning

confidence: 99%

“…Here, we examine molecular adaptations in the opsin gene repertoire of the cichlid species assemblage from crater Lake Barombi Mbo in Cameroon (West Africa) in relation to the environment and the trophic ecology of the species, and with a particular focus on adaptations towards deep‐water habitats with limited light penetration. Crater lake Barombi Mbo has a diameter of only 2.5 km but is more than 110 m deep (Trewavas, Green, & Corbet, ; Figure a) and hosts eleven endemic species of cichlid fishes ( Konia dikume , K. eisentrauti , Myaka myaka , Pungu maclareni , Sarotherodon steinbachi , S. lohbergeri , S. linnellii , S. caroli , Stomatepia mariae , St. mongo and St. pindu ; Figure c), which probably arose in situ following a colonization event no earlier than 1 million years ago (Cornen, Bande, Giresse, & Maley, ; Richards, Poelstra, & Martin, ; Schliewen & Klee, ). During this time frame, the species have diversified with respect to ecology, as documented by their trophic niche specialization (Baldo et al, ), as well as with respect to their water depth preference (Trewavas et al, ).…”

Section: Introductionmentioning

confidence: 99%

“…Crater lake Barombi Mbo has a diameter of only 2.5 km but is more than 110 m deep (Trewavas, Green, & Corbet, ; Figure a) and hosts eleven endemic species of cichlid fishes ( Konia dikume , K. eisentrauti , Myaka myaka , Pungu maclareni , Sarotherodon steinbachi , S. lohbergeri , S. linnellii , S. caroli , Stomatepia mariae , St. mongo and St. pindu ; Figure c), which probably arose in situ following a colonization event no earlier than 1 million years ago (Cornen, Bande, Giresse, & Maley, ; Richards, Poelstra, & Martin, ; Schliewen & Klee, ). During this time frame, the species have diversified with respect to ecology, as documented by their trophic niche specialization (Baldo et al, ), as well as with respect to their water depth preference (Trewavas et al, ). While nine out of the eleven Barombi Mbo cichlid species are commonly and syntopically found in the shallow littoral zone of the crater lake, two species have colonized the deep‐water zone: (a) K. dikume is an obligatory deep‐water specialist that inhabits the zone at around 20 m of depth (Trewavas et al, ); and (b) M. myaka is a seasonal deep‐water species that occurs in the deep‐water habitat during the dry season (November–April), yet migrates into the shallow littoral zone for spawning during the peak of the rainy season (June–August) (Trewavas et al, ).…”

Section: Introductionmentioning

confidence: 99%

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Evolution of the visual sensory system in cichlid fishes from crater lake Barombi Mbo in Cameroon

et al. 2019

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In deep‐water animals, the visual sensory system is often challenged by the dim‐light environment. Here, we focus on the molecular mechanisms involved in rapid deep‐water adaptations. We examined visual system evolution in a small‐scale yet phenotypically and ecologically diverse adaptive radiation, the species flock of cichlid fishes in deep crater lake Barombi Mbo in Cameroon, West Africa. We show that rapid adaptations of the visual system to the novel deep‐water habitat primarily occurred at the level of gene expression changes rather than through nucleotide mutations, which is compatible with the young age of the radiation. Based on retinal bulk RNA sequencing of all eleven species, we found that the opsin gene expression pattern was substantially different for the deep‐water species. The nine shallow‐water species feature an opsin palette dominated by the red‐sensitive (LWS) opsin, whereas the two unrelated deep‐water species lack expression of LWS and the violet‐sensitive (SWS2B) opsin, thereby shifting the cone sensitivity to the centre of the light spectrum. Deep‐water species further predominantly express the green‐sensitive RH2Aα over RH2Aβ. We identified one amino acid substitution in the RH2Aα opsin specific to the deep‐water species. We finally performed a comparative gene expression analysis in retinal tissue of deep‐ vs. shallow‐water species. We thus identified 46 differentially expressed genes, many of which are associated with functions in vision, hypoxia management or circadian clock regulation, with some of them being associated with human eye diseases.

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Section: Discussionmentioning

confidence: 56%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Evolution of the visual sensory system in cichlid fishes from crater lake Barombi Mbo in Cameroon

et al. 2019

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“…These co-authors therefore suggested that such data be expressed in percentage live weights. The high representation of the tilapias could be attributed to their high reproductive potential (Trewavas et al, 1972;Hepher and Pruginin, 1981) coupled with practice of parental care in that family (Beveridges and McAndrew, 2000).…”

Section: Discussionmentioning

confidence: 99%

A survey of fish species diversity and abundance in the White Volta at Nawuni, Northern Region, Ghana

Obodai¹,

Laweh²

2009

International Journal of Biological and Chemical Sciences

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The study was conducted in the White Volta River at Nawuni to identify the fishing gears used by the fishermen, assess fish species composition and their relative abundance. The results indicated that fishing gears such as gill nets, traps and hook-and-line were used. Most of the net mesh sizes used by the fishermen did not conform to those legally permitted by the Fisheries Department for inland capture fisheries. Forty-three (43) fish species belonging to seventeen (17) families were identified. The family Mochokidae had the highest species representation (7). Cichlidae were the most relatively abundant family (40%) with Sarotherodon galilaeus, scoring the greatest percentage frequency (29%). It is recommended that the use of 5.0 cm mesh size gill net should be encouraged to increase catch on a sustainable basis. Also S. galilaeus is recommended as the best species for culture based on the results of the study. It is concluded that fishing gears of mesh sizes lower than the recommended ones were used by the fishermen, and that the White Volta is rich in fish species diversity.

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Don't throw out the sympatric speciation with the crater lake water: fine-scale investigation of introgression provides equivocal support for causal role of secondary gene flow in one of the clearest examples of sympatric speciation

2018

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Genomic data has revealed complex histories of colonization and repeated gene flow previously unrecognized in some of the most celebrated examples of sympatric speciation and radiation. However, much of the evidence for secondary gene flow into these radiations comes from summary statistics calculated from sparse genomic sampling without knowledge of which specific genomic regions introgressed. This tells us little about how gene flow potentially influenced sympatric diversification. Here, we investigated whole genomes of Barombi Mbo crater lake cichlids for fine‐scale patterns of introgression with neighboring riverine cichlid populations. We found evidence of secondary gene flow into the radiation scattered across <0.24% of the genome; however, from our analyses, it is not clear if the functional diversity in these regions contributed to the ecological, sexual, and morphological diversity found in the lake. Unlike similar studies, we found no obvious candidate genes for adaptive introgression and we cannot rule out that secondary gene flow was predominantly neutral with respect to the diversification process. We also found evidence for differential assortment of ancestral polymorphisms found in riverine populations between sympatric sister species, suggesting the presence of an ancestral hybrid swarm. Although the history of gene flow and colonization is more complicated than previously assumed, the lack of compelling evidence for secondary gene flow's role in species diversification suggests that we should not yet rule out one of the most celebrated examples of sympatric speciation in nature without a more thorough investigation of the timing and functional role of each introgressed region.

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Ecological studies on crater lakes in West Cameroon Fishes of Barombi Mbo

Cited by 84 publications

References 17 publications

Evolution of the visual sensory system in cichlid fishes from crater lake Barombi Mbo in Cameroon

Evolution of the visual sensory system in cichlid fishes from crater lake Barombi Mbo in Cameroon

A survey of fish species diversity and abundance in the White Volta at Nawuni, Northern Region, Ghana

Don't throw out the sympatric speciation with the crater lake water: fine-scale investigation of introgression provides equivocal support for causal role of secondary gene flow in one of the clearest examples of sympatric speciation

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