Cryptic speciation in the Acari: a function of species lifestyles or our ability to separate species?

Abstract

There are approximately 55,000 described Acari species, accounting for almost half of all known Arachnida species, but total estimated Acari diversity is reckoned to be far greater. One important source of currently hidden Acari diversity is cryptic speciation, which poses challenges to taxonomists documenting biodiversity assessment as well as to researchers in medicine and agriculture. In this review, we revisit the subject of biodiversity in the Acari and investigate what is currently known about cryptic species within this group. Based on a thorough literature search, we show that the probability of occurrence of cryptic species is mainly related to the number of attempts made to detect them. The use of, both, DNA tools and bioassays significantly increased the probability of cryptic species detection. We did not confirm the generally-accepted idea that species lifestyle (i.e. free-living vs. symbiotic) affects the number of cryptic species. To increase detection of cryptic lineages and to understand the processes leading to cryptic speciation in Acari, integrative approaches including multivariate morphometrics, molecular tools, crossing, ecological assays, intensive sampling, and experimental evolution are recommended. We conclude that there is a demonstrable need for future investigations focusing on potentially hidden mite and tick species and addressing evolutionary mechanisms behind cryptic speciation within Acari.

DNA barcodes expose unexpected diversity in Canadian mites

“…Morphology‐based surveys have substantially underestimated mite diversity by neglecting cryptic taxa (Skoracka, Magalhães, Rector, & Kuczyński, ). By comparison, our BIN analysis provides a comprehensive assessment of the fauna by highlighting lineages where cryptic diversity prevails.…”

Incomplete species recognition entails few costs in spider mites, despite first-male precedence

“…Whether costs will be low in other spider mite species is unknown, but one could speculate that they may be higher in species that are more closely related to each other and hence produce hybrids. Indeed, many examples of cryptic speciation exist in mites, among which isolation is not complete (Skoracka et al 2015). In such cases, mating with a heterospecific may modify the future receptivity of females, especially in the case of first-male precedence.…”

Cryptic diversity within grass-associated Abacarus species complex (Acariformes: Eriophyidae), with the description of a new species, Abacarus plumiger n. sp.

“…In consequence, cryptic lineages or species evolve and their occurrence, being often overlooked, contributes to the underestimation of species richness (Gerhardt 2005;Stuart et al 2006;Bickford et al 2007;Pfenninger and Schwenk 2007;Ceballos and Ehrlich 2009;Wan et al 2014) and although cryptic species are widespread and common, the magnitude of cryptic diversity remains unknown (Bickford et al 2007;Pfenninger and Schwenk 2007;Stork 2018). Recognition of the extent of hidden diversity within any taxonomic group is essential to assess its overall diversity and to understand the complexity of its ecological interactions and evolutionary histories (Bickford et al 2007;Skoracka et al 2015). Furthermore, evaluation of cryptic diversity is of special importance for conservation biology, as well as for research on parasites and agricultural pests (Liu et al 2012;Poulin 2014).…”

“…Furthermore, increased access to molecular biology techniques had led to the development of barcoding procedures, which allowed fast species delimitation and discrimination on the genetic basis. As a result, many species that were initially described with traditional morphology-based methods as single taxonomic units, were later revealed to be complexes of cryptic species (Knowlton 1993;Funk et al 2012;Skoracka et al 2015). However, many of them, before correct identification with aid of genetic methods, had been suspected to be species complexes on the basis of their biological and ecological features (Henry and Wells 2010;Nygren et al 2010;Skoracka and Dabert 2010).…”