“More Than Meets the Eye”: Cryptic Diversity and Contrasting Patterns of Host-Specificity in Feather Mites Inhabiting Seabirds

Abstract

Feather mites are useful models for studying speciation due to their high diversity and strong degree of host specialization. However, studies to date have focused on the evolution of higher-level mite taxa while much hidden diversity likely occurs at the level of host genera and species. In this study, we examined the diversity and evolution of feather mites infesting six sympatric seabird species from six genera, breeding in the Cape Verde archipelago. We report 32 feather mite morphospecies categorized into 10 genera and three families, of which nine correspond to new, undescribed species. Molecular data corroborated morphological species descriptions, except for two morphologically-cryptic, but genetically distinct mite lineages related to Zachvatkinia oceanodromae and Laminalloptes simplex. Using these communities, we then applied a co-structure approach to test the contribution of ectosymbiont and host factors in driving feather mite evolution. Most seabird species hosted specific and unique feather mite species, even under sympatric conditions, and in general, feather mite species exhibited strong host-driven genetic structure. However, patterns of genetic differentiation were variable. That is, some mite species are more generalist than others and mite lineages/haplotypes can be shared by related seabird species. Interestingly, host-specific mites (e.g., Zachvatkinia spp.) tend to display much higher intra-specific diversity compared to more generalist mites (e.g., Microspalax and Plicatalloptes spp.). We discuss ectosymbiont and host life-history traits that might generate these patterns, such as host dispersal and breeding behavior and/or mite spatial and trophic specialization. Our findings highlight both the vast and largely unrecognized diversity of avian feather mites on seabirds, and the intrinsic complexity of the ecological processes underlying the evolution of these ectosymbionts.

Patterns of intraspecific morphological variability in soil mites reflect their dispersal ability

“…Unfortunately, non-phoretic females of S. acarorum were not available from different geographic locations to test whether their morphological pattern mirrors that of their phoretic conspecifics. Similar host-associated adaptive pressures have also been reported for other ectosymbionts such as feather mites (Stefan et al 2018 ).…”

Cryptic diversity within thePoecilochirus carabimite species complex phoretic onNicrophorus buryingbeetles: phylogeny, biogeography, and host specificity

“…Indeed, a relationship between genetic divergence and host specificity has also been reported from other parasites, such as the honey bee parasite Varroa (Beaurepaire et al, 2015) and Macrocheles species that are associated with Nicrophorus beetles (Knee, 2017). Genetic clustering driven by host adaptation is also found in feather mites that are phoretic on seabirds (Stefan et al, 2018). Host specificity is often seen as a species-level trait.…”

Parasites of seabirds: A survey of effects and ecological implications

“…Commonly harvested birds such as Common Eiders and murres have experienced pathogenicity, mortality, and even annual colony collapse due to increased parasitism (Gaston et al, 2002;Gaston and Elliott, 2013;Kristjánsson et al, 2016;Lovvorn et al, 2009). Anthropogenic activities such as overfishing and oceanic pollution are also evolving factors contributing to reduced health in seabirds (Braune et al, 2006;Sydeman et al, 2017). The long-term impacts of these changes can contribute to increased, additive mortality caused by parasites in seabird colonies.…”

“…A study by Stefan et al (2015) determined that a single bird can play host to multiple species of mites (Microspalax brevipes and Zachvatkinia ovate) due to resource partitioning and spatial segregation among the species. Indeed, a more recent study found up to eight different mite species exploiting Cape Verde Shearwaters (Calonectris edwardsii) and Bulwer's Petrels (Bulweria bulwerii; Stefan et al, 2018). However, the effects of mites on wild seabirds are largely unknown.…”

“…However, the effects of mites on wild seabirds are largely unknown. Studies on miteseabird interactions have focused on the phylogeny and co-evolution of mites and their hosts, rather than the impact of mite infestation itself (Choe and Kim, 1987;Coulson et al, 2009aCoulson et al, , 2009bStefan et al, 2018).…”