Genetic variability of Tunga penetrans (Siphonaptera, Tungidae) sand fleas across South America and Africa

Abstract

Tunga penetrans is a widely distributed sand flea, infecting men and domestic animals. It originated in South America, but it is now also endemic of Sub-Saharan Africa due to a recent accidental introduction. Previous genetic analyses indicated a very limited variability in the Ecuadorian populations; on the other hand, samples from Madagascar resulted to be genetically isolated. To better examine the genetic variability of T. penetrans, a wider sampling was analysed for mitochondrial (cytochrome oxidase II) and nuclear (ribosomal internal transcribed spacer [ITS] 2) DNA sequences. The mitochondrial marker confirms the low genetic variability, with few haplotypes characterizing the majority of individuals from different populations. Haplotype distribution is in agreement with a recent colonization of Africa and with a rapid spreading across this continent. Moreover, a consistent gene flow between the Pacific and Atlantic South American populations emerges, possibly due to human and/or animal cross-Andean dispersal. On the other hand, the ITS2 marker depicts a sharply diverging pattern with samples collected in Ecuador unequivocally distinguished from the Brazilian and African ones. On the whole, taking into account also the molecular features of the marker used, data here presented are better interpreted in the light of a high dispersal ability of T. penetrans, probably reducing the phylogeographic signal.

Repetitive sequences in the ITS1 region of the ribosomal DNA of Tunga penetrans and other flea species (Insecta, Siphonaptera)

“…All samples show no significant morphological differences. Comparable results have been obtained by Luchetti et al (2007) concerning a low variability of the ITS2 sequence within the populations. Despite the high dispersal ability of the sand fleas, they described a diverging ITS2 sequence pattern with samples collected in Ecuador distinguished from the Brazilian and African ones.…”

“…Additional markers frequently used are the cytochrome oxydase I, II and 16S rDNA mitochondrial genes. Some investigations of various flea species using molecular markers have been made and showed significant species specific sequence variations (Luchetti et al 2005(Luchetti et al , 2007Vobis et al 2005).…”

Ctenocephalides felis and Ctenocephalides canis: introgressive hybridization?

“…This result disagrees with that of Luchetti et al . () who found two genotypic groups (Atlantic and Pacific) in Tunga penetrans . Nevertheless, the peculiar evolutionary dynamics of ITS2, which is a repeated sequence embodied of rDNA, is well‐known.…”

Sand flea (Tunga spp.) infections in humans and domestic animals: state of the art

“…By contrast, samples from Madagascar were genetically isolated and differentiated from South American specimens (Luchetti et al ., 2005b). Therefore, the genetic variability of T. penetrans was examined through analysis of the COII mitochondrial gene and the ribosomal ITS2 nuclear region of a wider taxon sampling, which included eight populations from South America, from Ecuador to Brazil, and four African samples, from Zaire to Madagascar (Luchetti et al ., 2007). The mitochondrial marker confirmed a low genetic variability, with few haplotypes characterizing the majority of individuals from different populations.…”

“…The same sector's pattern within a pie indicates the same haplotype; the amplitude of each pie's sector is proportional to the frequency of the corresponding haplotype in the given population. The schematic tree indicates the phylogenetic relationships between Tunga populations as resulted from ITS2 nuclear markers analyses (black lines; Luchetti et al ., 2005c, 2007) and ITS1 (grey lines; Gamerschlag et al ., 2008).…”