Characterization of 17 Novel Polymorphic Microsatellite Loci in the Mammal Chewing Louse<i>Geomydoecus ewingi</i>(Insecta: Phthiraptera) for Population Genetic Analyses

Nessner, Caitlin; Andersen, John J.; Renshaw, Mark A.; Giresi, Melissa; Light, Jessica E.

doi:10.1645/13-415.1

Cited by 6 publications

(9 citation statements)

References 38 publications

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“…The process of population expansion has not, however, had any apparent effect on infrapopulation F IS , which is near zero for every infrapopulation of lice tested here (Table ). This finding is somewhat surprising given the tendency towards inbreeding of parasite populations (Nadler, ; Nessner et al, ), and it suggests that chewing louse infrapopulations are large enough at initial host colonization and mobile enough on a single host to avoid substantial inbreeding even in the face of population expansion into a new area.…”

Section: Discussionmentioning

confidence: 99%

Loss of genetic diversity, recovery and allele surfing in a colonizing parasite, Geomydoecus aurei

Demastes

Hafner

et al. 2019

Molecular Ecology

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Understanding the genetic consequences of changes in species distributions has wide‐ranging implications for predicting future outcomes of climate change, for protecting threatened or endangered populations and for understanding the history that has led to current genetic patterns within species. Herein, we examine the genetic consequences of range expansion over a 25‐year period in a parasite (Geomydoecus aurei) that is in the process of expanding its geographic range via invasion of a novel host. By sampling the genetics of 1,935 G. aurei lice taken from 64 host individuals collected over this time period using 12 microsatellite markers, we test hypotheses concerning linear spatial expansion, genetic recovery time and allele surfing. We find evidence of decreasing allelic richness (AR) with increasing distance from the source population, supporting a linear, stepping stone model of spatial expansion that emphasizes the effects of repeated bottleneck events during colonization. We provide evidence of post‐bottleneck genetic recovery, with average AR of infrapopulations increasing about 30% over the 225‐generation span of time observed directly in this study. Our estimates of recovery rate suggest, however, that recovery has plateaued and that this population may not reach genetic diversity levels of the source population without further immigration from the source population. Finally, we employ a grid‐based sampling scheme in the region of ongoing population expansion and provide empirical evidence for the power of allele surfing to impart genetic structure on a population, even under conditions of selective neutrality and in a place that lacks strong barriers to gene flow.

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Section: Discussionmentioning

confidence: 99%

Loss of genetic diversity, recovery and allele surfing in a colonizing parasite, Geomydoecus aurei

Demastes

Hafner

et al. 2019

Molecular Ecology

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“…Nessner et al . () found that 24–35% of the microsatellite loci they developed for G. ewingi , another chewing louse of pocket gophers, departed from Hardy–Weinberg expectations with substantial homozygote excess and high F IS values. However, because microsatellite loci are prone to null alleles, and because sample sizes were small in keeping with their purpose of primer development, it is not clear whether inbreeding will prove typical of that species of chewing louse when a greater number of infrapopulations are examined or whether many of the loci examined exhibit null alleles.…”

Section: Discussionmentioning

confidence: 99%

“…Nessner et al . () described a suite of microsatellite loci for Geomydoecus ewingi , chewing lice of the pocket gopher, Geomys breviceps , in Texas. Because the intent of that study was to describe microsatellite loci, population‐level parameters were only reported for a small number of lice from a small number of hosts, and a more thorough investigation of population genetics is warranted.…”

Section: Introductionmentioning

confidence: 99%

Host behaviour drives parasite genetics at multiple geographic scales: population genetics of the chewing louse,Thomomydoecus minor

et al. 2015

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Pocket gophers and their symbiotic chewing lice form a host-parasite assemblage known for a high degree of cophylogeny, thought to be driven by life history parameters of both host and parasite that make host switching difficult. However, little work to date has focused on determining whether these life histories actually impact louse populations at the very fine scale of louse infrapopulations (individuals on a single host) at the same or at nearby host localities. We used microsatellite and mtDNA sequence data to make comparisons of chewing-louse (Thomomydoecus minor) population subdivision over time and over geographic space where there are different potential amounts of host interaction surrounding a zone of contact between two hybridizing pocket-gopher subspecies. We found that chewing lice had high levels of population isolation consistent with a paucity of horizontal transmission even at the very fine geographic scale of a single alfalfa field. We also found marked genetic discontinuity in louse populations corresponding with host subspecies and little, if any, admixture in the louse genetic groups even though the lice are closely related. The correlation of louse infrapopulation differentiation with host interaction at multiple scales, including across a discontinuity in pocket-gopher habitat, suggests that host behaviour is the primary driver of parasite genetics. This observation makes sense in light of the life histories of both chewing lice and pocket gophers and provides a powerful explanation for the well-documented pattern of parallel cladogenesis in pocket gophers and chewing lice.

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“…Transmission of lice among hosts appears to require host-to-host contact (Timm, 1983), and the ability of a chewing louse to colonize new hosts is greatly limited by the louse's poor dispersal ability combined with the solitary nature of its host (Demastes et al, 2012;Harper, Spradling, Demastes, & Calhoun, 2015;Nadler, Hafner, Hafner, & Hafner, 1990;Nessner, Andersen, Renshaw, Giresi, & Light, 2014). As such, most colonization is from mother to offspring (Rust, 1974).…”

Section: Pocket Gophers Chewing Lice and History Of The San Acacimentioning

confidence: 99%

“…They are wingless insects that feed on skin detritus, and they spend their entire lives on their host and are highly host‐specific (Demastes, Hafner, Hafner, & Spradling, ; Marshall, ; Murray, ). Transmission of lice among hosts appears to require host‐to‐host contact (Timm, ), and the ability of a chewing louse to colonize new hosts is greatly limited by the louse's poor dispersal ability combined with the solitary nature of its host (Demastes et al, ; Harper, Spradling, Demastes, & Calhoun, ; Nadler, Hafner, Hafner, & Hafner, ; Nessner, Andersen, Renshaw, Giresi, & Light, ). As such, most colonization is from mother to offspring (Rust, ).…”

Section: Introductionmentioning

confidence: 99%

Temporal and spatial dynamics of competitive parapatry in chewing lice

Hafner

Spradling

et al. 2019

Ecology and Evolution

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We synthesize observations from 1979 to 2016 of a contact zone involving two subspecies of pocket gophers ( Thomomys bottae connectens and T. b. opulentus ) and their respective chewing lice ( Geomydoecus aurei and G. centralis ) along the Río Grande Valley in New Mexico, U.S.A., to test predictions about the dynamics of the zone. Historically, the natural flood cycle of the Rio Grande prevented contact between the two subspecies of pocket gophers. Flood control measures completed in the 1930s permitted contact, thus establishing the hybrid zone between the pocket gophers and the contact zone between their lice (without hybridization). Since that time, the pocket gopher hybrid zone has stabilized, whereas the northern chewing louse species has replaced the southern louse species at a consistent rate of ~150 m/year. The 0.2–0.8 width of the replacement zone has remained constant, reflecting the constant rate of chewing louse species turnover on a single gopher and within a local pocket gopher population. In contrast, the full width of the replacement zone (northernmost G. centralis to southernmost G. aurei ) has increased annually. By employing a variety of metrics of the species replacement zone, we are better able to understand the dynamics of interactions between and among the chewing lice and their pocket gopher hosts. This research provides an opportunity to observe active species replacement and resulting distributional shifts in a parasitic organism in its natural setting.

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Characterization of 17 Novel Polymorphic Microsatellite Loci in the Mammal Chewing LouseGeomydoecus ewingi(Insecta: Phthiraptera) for Population Genetic Analyses

Cited by 6 publications

References 38 publications

Loss of genetic diversity, recovery and allele surfing in a colonizing parasite, Geomydoecus aurei

Loss of genetic diversity, recovery and allele surfing in a colonizing parasite, Geomydoecus aurei

Host behaviour drives parasite genetics at multiple geographic scales: population genetics of the chewing louse,Thomomydoecus minor

Temporal and spatial dynamics of competitive parapatry in chewing lice

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