Abstract
Two endemic sardines in Lake Tanganyika, Limnothrissa miodon and Stolothrissa tanganicae, are important components of the lake’s total annual fishery harvest. These two species along with four endemic Lates species represent the dominant species in Lake Tanganyika’s pelagic fish community, in contrast to the complex pelagic communities in nearby Lake Malawi and Victoria. We use reduced representation genomic sequencing methods to gain a better understanding of possible genetic structure among and within populations of Lake Tanganyika’s sardines. Samples were collected along the Tanzanian, Congolese, and Zambian shores, as well as from nearby Lake Kivu, where Limnothrissa was introduced in 1959. Our results reveal unexpected cryptic differentiation within both Stolothrissa and Limnothrissa. We resolve this genetic structure to be due to the presence of large sex-specific regions in the genomes of both species, but involving different polymorphic sites in each species. Additionally, we find a large segregating inversion in Limnothrissa. We find all inversion karyotypes throughout the lake, but the frequencies vary along a north-south gradient within Lake Tanganyika, and differ substantially in the introduced Lake Kivu population. Little to no spatial genetic structure exists outside the inversion, even over the hundreds of kilometres covered by our sampling. These genetic analyses show that Lake Tanganyika’s sardines have dynamically evolving genomes, and the analyses here represent a key first step in understanding the genetic structure of the Lake Tanganyika pelagic sardines.
Footnotes
We have corrected a typo in one of the authors' names.
