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Background: The population history of Plasmodium simium, which causes malaria in sylvatic Neotropical monkeys and humans along the Atlantic Coast of Brazil, remains disputed. Genetically diverse P vivax populations from various sources, including the lineages that founded the species P simium, are thought to have arrived in the Americas in separate migratory waves.Methods: We use population genomic approaches to investigate the origin and evolution of P simium.Results: We find a minimal genome-level differentiation between P simium and present-day New World P vivax isolates, consistent with their common geographic origin and subsequent divergence on this continent. The meagre genetic diversity in P simium samples from humans and monkeys implies a recent transfer from humans to non-human primates - a unique example of malaria as a reverse zoonosis of public health significance. Likely genomic signatures of P simium adaptation to new hosts include the deletion of >40% of a key erythrocyte invasion ligand, PvRBP2a, which may have favored more efficient simian host cell infection.Conclusions: New World P vivax lineages that switched from humans to platyrrhine monkeys founded the P simium population that infects nonhuman primates and feeds sustained human malaria transmission in the outskirts of major cities. [ABSTRACT FROM AUTHOR]

Background: Anopheles (Kerteszia) cruzii (Diptera: Culicidae) is a primary vector of human and simian malaria parasites in southern and southeastern Brazil. Earlier studies using chromosome inversions, isoenzymes and a number of molecular markers have suggested that An. cruzii is a species complex. Results: In this study, a multilocus approach using six loci, three circadian clock genes and three encoding ribosomal proteins, was carried out to investigate in more detail the genetic differentiation between the An. cruzii populations from Florianópolis-Santa Catarina (southern Brazil) and Itatiaia-Rio de Janeiro States (southeastern Brazil). The analyses were performed first comparing Florianópolis and Itatiaia, and then comparing the two putative sympatric incipient species from Itatiaia (Itatiaia A and Itatiaia B). The analysis revealed high FST values between Florianópolis and Itatiaia (considering Itatiaia A and B together) and also between the sympatric Itatiaia A and Itatiaia B, irrespective of their function. Also, using the IM program, no strong indication of migration was found between Florianópolis and Itatiaia (considering Itatiaia A and B together) using all loci together, but between Itatiaia A and Itatiaia B, the results show evidence of migration only in the direction of Itatiaia B. Conclusions: The results of the multilocus analysis indicate that Florianópolis and Itatiaia represent different species of the An. cruzii complex that diverged around 0.6 Mya, and also that the Itatiaia sample is composed of two sympatric incipient species A and B, which diverged around 0.2 Mya. Asymmetric introgression was found between the latter two species despite strong divergence in some loci. [ABSTRACT FROM AUTHOR]

Background: Anopheles cruzii is the primary human Plasmodium vector in southern and southeastern Brazil. The distribution of this mosquito follows the coast of the Brazilian Atlantic Forest. Previous studies indicated that An. cruzii is a complex of cryptic species. Results: A multilocus approach using six loci, three circadian clock genes and three encoding ribosomal proteins, was implemented to investigate in more detail the genetic differentiation between the An. cruzii populations from Santa Catarina (southern Brazil) and Bahia States (northeastern Brazil) that represent two sibling species. The analysis revealed very high FST values and fixed differences between the two An. cruzii sibling species in all loci, irrespective of their function. An Isolation with Migration model was fit to the data using the IM program. The results reveal no migration in either direction and allowed a rough estimate of the divergence time between the two sibling species. Conclusions: Population genetics analysis of An. cruzii samples from two Brazilian localities using a multilocus approach confirmed that they represent two different sibling species in this complex. The results suggest that the two species have not exchanged migrants since their separation and that they possibly diverged between 1.1 and 3.6 million years ago, a period of intense climatic changes. [ABSTRACT FROM AUTHOR]

Background: Anopheles cruzii (Diptera: Culicidae) has long been known as a vector of human and simian malaria parasites in southern and south-eastern Brazil. Previous studies have provided evidence that An. cruzii is a species complex, but the status of the different populations and the number of sibling species remains unclear. A recent analysis of the genetic differentiation of the timeless gene among An. cruzii populations from south and south-east Brazil has suggested that the population from Itatiaia, Rio de Janeiro State (south-east Brazil), is in a process of incipient speciation. Methods: A ∼180 bp fragment of cpr, a gene encoding the NADPH-cytochrome P450 reductase, an enzyme involved in metabolic insecticide resistance and odorant clearance in insects, was used in this study as a molecular marker to analyse the divergence between five An. cruzii populations from south and south-east Brazil. Results: Analysis of the genetic differentiation in the cpr gene revealed very high FST values and fixed differences between Itatiaia and the other four populations studied (Florianópolis, Cananéia, Juquitiba and Santa Teresa). In addition, the data also provided preliminary evidence that seems to indicate the occurrence of two sympatric sibling species in Itatiaia. Conclusions: Population genetics analysis of An. cruzii samples from different localities using a fragment of the cpr gene suggests that the Itatiaia sample represents at least one new sibling species in this complex. [ABSTRACT FROM AUTHOR]

Background: Anopheles (Kerteszia) cruzii was the most important vector of human malaria in southern Brazil between 1930-1960. Nowadays it is still considered an important Plasmodium spp. vector in southern and south-eastern Brazil, incriminated for oligosymptomatic malaria. Previous studies based on the analysis of X chromosome banding patterns and inversion frequencies in An. cruzii populations from these areas have suggested the occurrence of three sibling species. In contrast, two genetically distinct groups among An. cruzii populations from south/south-east and north-east Brazil have been revealed by isoenzyme analysis. Therefore, An. cruzii remains unclear. Methods: In this study, a partial sequence of the timeless gene (~400 bp), a locus involved in the control of circadian rhythms, was used as a molecular marker to assess the genetic differentiation between An. cruzii populations from six geographically distinct areas of Brazil. Results: The timeless gene revealed that An. cruzii from Itaparica Island, Bahia State (north-east Brazil), constitutes a highly differentiated group compared with the other five populations from south and south-east Brazil. In addition, significant genetic differences were also observed among some of the latter populations. Conclusion: Analysis of the genetic differentiation in the timeless gene among An. cruzii populations from different areas of Brazil indicated that this malaria vector is a complex of at least two cryptic species. The data also suggest that further work might support the occurrence of other siblings within this complex in Brazil. [ABSTRACT FROM AUTHOR]

Plasmodium simium, a malaria parasite that infects platyrrhine monkeys and humans in the New World, is nearly identical to Plasmodium vivax. Recent genomic comparative analyses of these sister species have identified elevated divergence in a gene that may underlie P. simium adaptation to non-human primates during its gradual speciation process., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2021 Elsevier Ltd. All rights reserved.)