High Levels of Genetic Differentiation between Ugandan Glossina fuscipes fuscipes Populations Separated by Lake Kyoga

The two types of sleeping sickness in West and East Africa are markedly distinct, require different treatments, and are caused by different parasites. The only country where both parasites are present is Uganda, where they are separated by a narrow 160 km disease-free belt. Because there is no restriction on the movement of humans and animals between the two disease zones, this separation is puzzling. We asked whether this disjunct distribution can be explained by variation within the tsetse fly that is largely responsible for transmitting both diseases in Uganda, Glossina fuscipes fuscipes. We therefore examined whether this tsetse subspecies is genetically uniform across Uganda. Our results indicate that G. f. fusicipes is not genetically different between the two disease zones, but there are clear genetic differences between northern and southern populations, which are separated by Lake Kyoga. Therefore, it is unlikely that variation in the tsetse fly determines the distribution of the two parasites. This implies that the two diseases may fuse in the near future, which would greatly complicate diagnosis and treatment of sleeping sickness in any potential area of overlap

Multiple evolutionary origins of Trypanosoma evansi in Kenya

Trypanosoma evansi is the parasite causing surra, a form of trypanosomiasis in camels and other livestock, and a serious economic burden in Kenya and many other parts of the world. Trypanosoma evansi transmission can be sustained mechanically by tabanid and Stomoxys biting flies, whereas the closely related African trypanosomes T. brucei brucei and T. b. rhodesiense require cyclical development in tsetse flies (genus Glossina) for transmission. In this study, we investigated the evolutionary origins of T. evansi. We used 15 polymorphic microsatellites to quantify levels and patterns of genetic diversity among 41 T. evansi isolates and 66 isolates of T. b. brucei (n = 51) and T. b. rhodesiense (n = 15), including many from Kenya, a region where T. evansi may have evolved from T. brucei. We found that T. evansi strains belong to at least two distinct T. brucei genetic units and contain genetic diversity that is similar to that in T. brucei strains. Results indicated that the 41 T. evansi isolates originated from multiple T. brucei strains from different genetic backgrounds, implying independent origins of T. evansi from T. brucei strains. This surprising finding further suggested that the acquisition of the ability of T. evansi to be transmitted mechanically, and thus the ability to escape the obligate link with the African tsetse fly vector, has occurred repeatedly. These findings, if confirmed, have epidemiological implications, as T. brucei strains from different genetic backgrounds can become either causative agents of a dangerous, cosmopolitan livestock disease or of a lethal human disease, like for T. b. rhodesiense

Data from: Multiple evolutionary origins of Trypanosoma evansi in Kenya

Trypanosoma evansi is the parasite causing surra, a form of trypanosomiasis in camels and other livestock, and a serious economic burden in Kenya and many other parts of the world. Trypanosoma evansi transmission can be sustained mechanically by tabanid and Stomoxys biting flies, whereas the closely related African trypanosomes T. brucei brucei and T. b. rhodesiense require cyclical development in tsetse flies (genus Glossina) for transmission. In this study, we investigated the evolutionary origins of T. evansi. We used 15 polymorphic microsatellites to quantify levels and patterns of genetic diversity among 41 T. evansi isolates and 66 isolates of T. b. brucei (n = 51) and T. b. rhodesiense (n = 15), including many from Kenya, a region where T. evansi may have evolved from T. brucei. We found that T. evansi strains belong to at least two distinct T. brucei genetic units and contain genetic diversity that is similar to that in T. brucei strains. Results indicated that the 41 T. evansi isolates originated from multiple T. brucei strains from different genetic backgrounds, implying independent origins of T. evansi from T. brucei strains. This surprising finding further suggested that the acquisition of the ability of T. evansi to be transmitted mechanically, and thus the ability to escape the obligate link with the African tsetse fly vector, has occurred repeatedly. These findings, if confirmed, have epidemiological implications, as T. brucei strains from different genetic backgrounds can become either causative agents of a dangerous, cosmopolitan livestock disease or of a lethal human disease, like for T. b. rhodesiense

Data from: Genetic rediscovery of an ‘extinct’ Galápagos giant tortoise species

Genes from recently extinct species can live on in the genomes of extant individuals of mixed ancestry. Recently, Poulakakis et al. detected genetic signatures of the giant Galápagos tortoise once endemic to Floreana Island (Chelonoidis elephantopus) within eleven hybrid individuals of otherwise pure C. becki on Volcano Wolf, Isabela Island. Movement of tortoises among islands by pirate and whaling ships was not uncommon during the 1800’s, representing a likely mechanism by which individuals from Floreana were translocated to northern Isabela, despite being presumed extinct soon after Charles Darwin’s historic voyage to the Galápagos Islands in 1835. These eleven hybrid individuals with C. elephantopus ancestry were thought to be the last genetic vestiges of a unique evolutionary lineage in the wild. Here we report that reproductively mature purebred tortoises of the recently ‘extinct’ C. elephantopus from Floreana Island are very likely still alive today, as identified and tracked through the genetic footprints’ left in the genomes of very recent hybrid offspring on Volcano Wolf, Isabela Island. If found, these purebred C. elephantopus individuals could constitute core founders of a captive breeding program directed towards resurrecting this species

The genetic legacy of Lonesome George survives: Giant tortoises with Pinta Island ancestry identified in Galápagos

The death of Lonesome George, the last known purebred individual of Chelonoidis abingdoni native to Pinta Island, marked the extinction of one of 10 surviving giant tortoise species from the Galápagos Archipelago. Using a DNA reference dataset including historical C. abingdoni and >1600 living Volcano Wolf tortoise samples, a site on Isabela Island known to harbor hybrid tortoises, we discovered 17 individuals with ancestry in C. abingdoni. These animals belong to various hybrid categories, including possible first generation hybrids, and represent multiple, unrelated individuals. Their ages and relative abundance suggest that additional hybrids and conceivably purebred C. abingdoni individuals still occur on Volcano Wolf. Spatial analyses suggest locations where additional individuals with C. abingdoni ancestry are most likely to be recovered, consistent with historical records of human movement of tortoises. These results provide an opportunity for species recovery of Pinta Island tortoises using individuals with C. abingdoni ancestry

The genetic legacy of Lonesome George survives: Giant tortoises with Pinta Island ancestry identified in Galápagos

The death of Lonesome George, the last known purebred individual of Chelonoidis abingdoni native to Pinta Island, marked the extinction of one of 10 surviving giant tortoise species from the Galápagos Archipelago. Using a DNA reference dataset including historical C. abingdoni and >1600 living Volcano Wolf tortoise samples, a site on Isabela Island known to harbor hybrid tortoises, we discovered 17 individuals with ancestry in C. abingdoni. These animals belong to various hybrid categories, including possible first generation hybrids, and represent multiple, unrelated individuals. Their ages and relative abundance suggest that additional hybrids and conceivably purebred C. abingdoni individuals still occur on Volcano Wolf. Spatial analyses suggest locations where additional individuals with C. abingdoni ancestry are most likely to be recovered, consistent with historical records of human movement of tortoises. These results provide an opportunity for species recovery of Pinta Island tortoises using individuals with C. abingdoni ancestry

Kamidi et al. 2017 genotypes_GENEPOP

GENEPOP format. Populations according to STRUCTURE results K=7 as described in Kamidi et al. 2017