Divergent selection following speciation in two ectoparasitic honey bee mites

Abstract

31Multispecies host-parasite evolution is common, but how parasites evolve after speciating 32 remains poorly understood. Shared evolutionary history and physiology may propel species 33 along similar evolutionary trajectories whereas pursuing different strategies can reduce 34 competition. We test these scenarios in the economically important association between honey 35 bees and ectoparasitic mites by sequencing the genomes of the sister mite species Varroa 36 destructor and Varroa jacobsoni. These genomes were closely related, with 99.7% sequence 37 identity. Among the 9,628 orthologous genes, 4.8% showed signs of positive selection in at least 38 one species. Divergent selective trajectories were discovered in conserved chemosensory gene 39 families (IGR, SNMP), and Halloween genes (CYP) involved in moulting and reproduction. 40 However, there was little overlap in these gene sets and associated GO terms, indicating 41 different selective regimes operating on each of the parasites. Based on our findings, we 42 suggest that species-specific strategies may be needed to combat evolving parasite 43 communities. 45Interactions between hosts and parasites shape biodiversity by driving coevolutionary 46 arms races and by regulating populations over ecological timescales. Parasitism is a remarkably 47 109 41 and linking oogenesis initiation or failure to parasitic reduced metabolism and host defense 110 44,45 . 111Here, we ask how both mite species have arrived at this tolerance equilibrium in A. 112 ceranadid they follow similar or different evolutionary paths? On one hand, the two species 113 naturally occur in parapatry ( Figure 1B), which is expected to result from divergent local 114 adaptation with the distribution of different A. cerana lineages 46,47 . In actuality, what drives the 115 parapatric distribution is unclear. V. destructor, which was historically absent from Southeast 116 Asia, now occurs there on its novel host A. mellifera in sympatry with V. jacobsoni, which does 117 not parasitize A. mellifera in this region ( Figure 1C). Thus, it is possible that the current 118 geographical distribution resulted from secondary contact following allopatric speciation. This 119 view is further supported by the fact that both species have the genetic capacity to shift to A. 120 mellifera as a novel host, suggesting a level of physiological similarity. We tested these 121 alternative hypotheses (parallel vs. divergent evolution) by generating high-quality hybrid de 122 novo genome assembly of both species and examining them for signatures of adaptive 123 evolution. We also compared them to the recently published genome of a distantly related 124 ectoparasitic mite Tropilaelaps mercedesae, to see whether the patterns appear universal at 125 different timescales. 126 127 128 129 Figure 1: V. destructor and V. jacobsoni are morphologically similar sister species originally parasitizing 130 the eastern honey bee (A. cerana). These species were recognized upon the basis of quantitative 131 morphometric an...

A genome-wide screening for RNAi pathway proteins in Acari

“…Asterick (*) indicates species with fully annotated genomes whereas no Asterick indicates species with a partial annotated genomes. aFrom Cornman et al [83], bFrom Techer et al [84], cFrom Hoy et al [85], dFrom Dong et al [86], eFrom Miller et al [87], fFrom Grbić et al [88], gFrom Rider et al [89], hFrom Rider et al [90], iFrom Waldron et al [91].…”

Evolutionary emergence of Hairless as a novel component of the Notch signaling pathway

“…Species names are as follows: Smar ( Strigamia maritima ); Hsub ( Hydroschendyla submarina ) (Fernández et al, 2016); Agir ( Anopsobius giribeti ) (Fernández et al, 2016); Onosp ( Onomeris sp.) (Rodriguez et al, 2018); Slm ( Sigmoria latior munda ) (Rodriguez et al, 2018); Ptep ( Parasteatoda tepidariorum ); Hruf ( Hypochthonius rufulus ) (Bast et al, 2016); Ssca ( Sarcoptes scabiei ); Vjac ( Varroa jacobsoni ) (Techer et al, 2019); Iper ( Ixodes persulcatus ); Mmar ( Mesobuthus martensii ) (Cao et al, 2013); Lpol ( Limulus polyphemus ). We note that Maier (2019) has previously described the presence of the SBD-like element in the Strigamia maritima sequence.…”

“…Some exceptions to this pattern do exist. In the genomes of the mites Metaseiulus occidentalis (Supplementary file 4) and Varroa destructor (Techer et al, 2019), for example, the genes encoding S-CAP and MTA are far separated from each other.…”