Figure 6 from: Dierickx K, Hanssens M, Rusuwa B, Snoeks J (2018) Trematocranus pachychilus, a new endemic cichlid from Lake Malawi (Teleostei, Cichlidae). ZooKeys 743: 153-166. https://doi.org/10.3897/zookeys.743.22814

A new species of Trematocranus, T. pachychilus sp. n., is described from Lake Malawi. So far, it has only been found at Jafua Bay, Mozambique. It can easily be distinguished from T. labifer by its molariform pharyngeal dentition. A morphometric study, including 24 measurements and 15 counts, was done to compare the new species with T. microstoma and T. placodon. Trematocranus pachychilus is characterised by its thick lips. This species further differs from T. microstoma by its bicuspid (vs. unicuspid) outer oral teeth, wide (vs. small) pharyngeal bone, and its head shape. It resembles T. placodon, from which it can be distinguished by its straight to concave head profile (vs. rounded), less-developed pharyngeal bones (vs. hypertrophied), and the presence of small to minute teeth on the lateral parts of the dentigerous area on the lower pharyngeal bone. A key to the species of Trematocranus is provided

Asymmetric interspecific territorial competition over food resources amongst Lake Malawi cichlid fishes

The rock-dwelling cichlids in Lake Malawi comprise the most diverse freshwater fish community in the world. Individuals frequently interact with heterospecifics through feeding territoriality. Underwater observations and experiments were conducted to examine interspecific variation in the frequencies of territorial behaviour and its influence on the feeding habits of heterospecifics. Frequencies of chasing and fleeing associated with interspecific territoriality were remarkably different amongst 10 cichlid species. In addition, individual fish that attacked heterospecifics more frequently were attacked less often by them, suggesting that interspecific interactions amongst cichlid species are asymmetric. The experimental removal of territory owners belonging to the most aggressive species resulted in almost fivefold increase in feeding within territories, suggesting that territorial aggression preserves food resources for the territory holder and influences the feeding habits of other species, including those with some dietary dissimilarities. Additional information regarding asymmetric interspecific interactionswould improve understanding about how diverse cichlids within trophic groups manage to coexist.African Zoology 45(1): 24–31 (April 2010

Trematocranus pachychilus, a new endemic cichlid from Lake Malawi (Teleostei, Cichlidae)

A new species of Trematocranus, T. pachychilus sp. n., is described from Lake Malawi. So far, it has only been found at Jafua Bay, Mozambique. It can easily be distinguished from T. labifer by its molariform pharyngeal dentition. A morphometric study, including 24 measurements and 15 counts, was done to compare the new species with T. microstoma and T. placodon. Trematocranus pachychilus is characterised by its thick lips. This species further differs from T. microstoma by its bicuspid (vs. unicuspid) outer oral teeth, wide (vs. small) pharyngeal bone, and its head shape. It resembles T. placodon, from which it can be distinguished by its straight to concave head profile (vs. rounded), less-developed pharyngeal bones (vs. hypertrophied), and the presence of small to minute teeth on the lateral parts of the dentigerous area on the lower pharyngeal bone. A key to the species of Trematocranus is provided

Natural variation at a single gene generates sexual antagonism across fitness components in Drosophila

Mutations with conflicting fitness effects in males and females accumulate in sexual populations, reducing their adaptive capacity.1,2 Although quantitative genetic studies indicate that sexually antagonistic polymorphisms are common,3-5 their molecular basis and population genetic properties remain poorly understood.6,7 Here, we show in fruit flies how natural variation at a single gene generates sexual antagonism through phenotypic effects on cuticular hydrocarbon (CHC) traits that function as both mate signals and protectors against abiotic stress8 across a latitudinal gradient. Tropical populations of Drosophila serrata have polymorphic CHCs producing sexual antagonism through opposing but sex-limited effects on these two fitness-related functions. We dissected this polymorphism to a single fatty-acyl CoA reductase gene, DsFAR2-B, that is expressed in oenocyte cells where CHCs are synthesized. RNAi-mediated disruption of the DsFAR2-B ortholog in D. melanogaster oenocytes affected CHCs in a similar way to that seen in D. serrata. Population genomic analysis revealed that balancing selection likely operates at the DsFAR2-B locus in the wild. Our study provides insights into the genetic basis of sexual antagonism in nature and connects sexually varying antagonistic selection on phenotypes with balancing selection on genotypes that maintains molecular variation

Asymmetric interspecific territorial competition over food resources amongst lake malawi cichlid fishes

The rock-dwelling cichlids in Lake Malawi comprise the most diverse freshwater fish community in the world, Individuals frequently interact with heterospecifics through feeding territoriality. Underwater observations and experiments were conducted to examine interspecific variation in the frequencies of territorial behaviour and its influence on the feeding habits of heterospecifics. Frequencies of chasing and fleeing associated with interspecific territoriality were remarkably different amongst 10 cichlid species. In addition, individual fish that attacked heterospecifics more frequently were attacked less often by them, suggesting that interspecific interactions amongst cichlid species are asymmetric, The experimental removal of territory owners belonging to the most aggressive species resulted in almost fivefold increase in feeding within territories, suggesting that territorial aggression preserves food resources for the territory holder and influences the feeding habits of other species, including those with some dietary dissimilarities. Additional information regarding asymmetric interspecific interactions would improve understanding about how diverse cichlids within trophic groups manage to coexist