Abstract
BackgroundNumerous studies have investigated cospeciation between parasites and their hosts, but there have been few studies concerning parasitoids and insect hosts. The high diversity and host specialization observed in Anicetus species suggest that speciation and adaptive radiation might take place with species diversification in scale insect hosts. Here we examined the evolutionary history of the association between Anicetus species and their scale insect hosts via distance-based and tree-based methods.ResultsA total of 94 Anicetus individuals (nine parasitoid species) and 113 scale insect individuals (seven host species) from 14 provinces in China were collected in the present study. DNA sequence data from a mitochondrial gene (COI) and a nuclear ribosomal gene (28S D2 region) were used to reconstruct the phylogenies of Anicetus species and their hosts. The distance-based analysis showed a significant fit between Anicetus species and their hosts, but tree-based analyses suggested that this significant signal could be observed only when the cost of host-switching was high, indicating the presence of parasite sorting on related host species.ConclusionsThis study, based on extensive rearing of parasitoids and species identification, provides strong evidence for a prevalence of sorting events and high host specificity in the genus Anicetus, offering insights into the diversification process of Anicetus species parasitizing scale insects.
Highlights
Numerous studies have investigated cospeciation between parasites and their hosts, but there have been few studies concerning parasitoids and insect hosts
In the last two decades, several methods were developed to assess the level of cospeciation in symbiotic associations [8], and the availability of programs such as TreeMap [9], TreeFitter [10,11] and ParaFit [12] has led to an increased level of accuracy in host-parasite cospeciation studies [13,14,15]
This test compared the summed lengths of most-parsimonious trees computed from each dataset to the lengths of trees generated from random partitions of the combined sequences of both genes [52], and calculated the probability of obtaining a random tree similar or shorter to the length of observed summed tree
Summary
Numerous studies have investigated cospeciation between parasites and their hosts, but there have been few studies concerning parasitoids and insect hosts. In the last two decades, several methods were developed to assess the level of cospeciation in symbiotic associations [8], and the availability of programs such as TreeMap [9], TreeFitter [10,11] and ParaFit [12] has led to an increased level of accuracy in host-parasite cospeciation studies [13,14,15]. These software search for an optimal evolutionary scenario for the association between hosts and their symbionts (for example, parasites). Cophylogeny between parasitoids and their insect hosts has been rarely investigated, with the few previous studies focusing on Lepidoptera-parasitoids systems [31,32]
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