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

Laura M Stefan,Sergey V Mironov,Elena Gómez-Díaz,Jacob González-Solís,Karen D Mccoy

doi:10.3389/fevo.2018.00097

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 ten 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 (eg., Zachvatkinia spp.) tend to display much higher intra-specific diversity compared to more generalist mites (eg., 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.

Highlights

By definition, parasites and symbionts depend almost entirely on their host for survival and transmission, and have evolved intricate adaptations to optimize their life cycle (de Meeûs et al, 1998; Criscione et al, 2005)
We explore the diversity and genetic structure of feather mite species inhabiting the community of procellariform seabirds of the Cape Verde Islands
We evaluated the partitioning of genetic variation within and between feather mite populations, using one-way analyses of molecular variance (AMOVA) in ARLEQUIN version 3.5 and determined significance using 10,000 permutations

Summary

Introduction

Parasites and symbionts depend almost entirely on their host for survival and transmission, and have evolved intricate adaptations to optimize their life cycle (de Meeûs et al, 1998; Criscione et al, 2005). Multiple host and parasite/symbiont life-history traits can influence the specificity of an interaction and the resulting population structure of the parasite/symbiont (i.e., dispersal and drift, host ecology and behavior, symbiont lifecycle complexity and demography) (Blouin et al, 1995; McCoy et al, 2003; Criscione and Blouin, 2004; Bruyndonckx et al, 2009; Mazé-Guilmo et al, 2016) This can lead to conflicting predictions on patterns of structure. Few studies have used this multispecies and multi-scale approach (but see Johnson et al, 2002; Rivera-Parra et al, 2015)

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