Kilford, H. | bioRxiv Science

bioRxiv2024

Estimating the rate of sexual reproduction and the inbreeding rate in Leishmania

Many eukaryotic species undergo sexual reproduction facultatively, either in response to stress or in particular environments. For the remainder of their life cycle they reproduce by mitosis. This facultative sex may be rare, which alters features of their evolutionary dynamics. Both the frequency of sex and the degree of inbreeding have been challenging to estimate from genome-scale polymorphism data. Here, we describe a method to estimate both these parameters based on the Moran model of heterozygous sites. We apply this method to population genomic data from Leishmania parasitic protozoans from the Leishmania donovani species complex, showing that these parasites undergo sexual reproduction approximately once per 10,000 generations and that populations vary considerably in the extent of their inbreeding.

genetics↗

bioRxiv2021

Multiple targets of balancing selection in Leishmania donovani complex parasites

The Leishmania donovani species complex are the causative agents of visceral leishmaniasis, which cause 20-40,000 fatalities a year. Here, we conduct a screen for balancing selection in this species complex. We used 387 publicly-available L. donovani and L. infantum genomes, and sequence 93 isolates of L. infantum from Brazil to describe the global diversity of this species complex. We identify five genetically-distinct populations that are sufficiently represented by genomic data to search for signatures of selection. We find that signals of balancing selection are generally not shared between populations, consistent with transient adaptive events, rather than long-term balancing selection. We then apply multiple diversity metrics to identify candidate genes with robust signatures of balancing selection, identifying a curated set of 19 genes with robust signatures. These include zeta toxin, nodulin-like and flagellum attachment proteins. This study highlights the extent of genetic divergence between L. donovani complex parasites and provides genes for further study.

evolutionary biology↗