Project R-13801

"With a pinch of salt: habitat variability promoting plasticity and hampering diversification in a hostparasite system?" (Research)

Species diversity is unevenly spread: some lineages are highly species-rich, others are not. Though speciation research focuses on the former, understanding why lineages fail to diverge is crucial too. Parasites typically speciate faster than hosts, especially large and long-lived hosts, and become more species-rich. Our research team found that all African lates perches, some of the largest freshwater fishes, host only a single monogenean flatworm: Dolicirroplectanum lacustre, infecting gills. Similarly, only one species, D. penangi is known from Indo-Pacific Lates calcarifer. We will investigate this pattern to reveal phenotypic and genomic mechanisms underlying failure to diverge in this parasitic lineage. We hypothesise that variability of a wide range of inland and coastal water habitats, amplified by constraints imposed by the host gills, forces Dolicirroplectanum into phenotypic plasticity and prevents diversification. We will investigate the morphological, physiological and genomic variability of the parasites in light of these aspects of their host populations. Our comprehensive sample design, based on historical collections, includes the related but more species-rich parasite Laticola infecting Indo-Pacific L. calcarifer for comparison of speciation patterns. Understanding an unexpected lack of diversification by integrating morphological, physiological and genomic diversity of hosts and their less species-rich parasites is a novel approach to study speciation.

01 October 2023 - 30 September 2027