Lousy big guys: Lepidophthirus macrorhini infesting seals from Antarctica

Herrera

Sweet

et al. 2019

Systematic Entomology

Self Cite

Lice are considered a model system for studying the process of cospeciation because they are obligate and permanent parasites and are often highly host‐specific. Among lice, species in the family Echinophthiriidae Enderlein (Anoplura) are unique in that they infest mammalian hosts with an amphibious lifestyle, i.e. pinnipeds and the river otter. There is evidence that the ancestor of this group infested the terrestrial ancestor of pinnipeds, which suggests these parasites coevolved with their hosts during the transition to marine environments. However, there has been no previous study investigating the phylogenetic relationships among sucking lice parasitizing seals and sea lions. To uncover the evolutionary history of these parasites, we obtained genomic data for Antarctophthirus microchir Trouessart and Neumann (from two hosts), Antarctophthirus carlinii Leonardi et al., Antarctophthirus lobodontis Enderlein, Antarctophthirus ogmorhini Enderlein, Lepidophthirus macrorhini Enderlein, and Proechinophthirus fluctus Ferris. From genomic sequence reads, we assembled > 1000 nuclear genes and used these data to infer a phylogenetic tree for these lice. We also used the assembled genes in combination with read‐mapping to estimate heterozygosity and effective population size from individual lice. Our analysis supports the monophyly of lice from pinnipeds and uncovers phylogenetic relationships within the group. Surprisingly, we found that A. carlinii, A. lobodontis, and A. ogmorhini have very little genetic divergence among them, whereas the divergence between different geographic representatives of A. microchir indicate that they are possibly different species. Nevertheless, our phylogeny of Echinophthiriidae suggests that these lice have consistently codiverged with their hosts with minimal host switching. Population genomic metrics indicate that louse effective population size is linked to host demographics, which further highlights the close association between pinnipeds and their lice.

Section: Methodsmentioning

confidence: 99%

Phylogenomic analysis of seal lice reveals codivergence with their hosts

Herrera

Sweet

et al. 2019

Systematic Entomology

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“…The only evidence available suggesting that they do, comes from the finding in Antarctica of lice-infested adult seals. Given that infestation usually takes place as pups, lice on those adult seals have probably been living on their hosts for several months or years (Leonardi et al, 2018). Although suggestive, this is not definitive evidence that lice were already present when seals came ashore.…”

Section: Introductionmentioning

confidence: 93%

Under pressure: the extraordinary survival of seal lice in the depth of the sea

Journal of Experimental Biology

Crespo

Soto

et al. 2020

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Lice from pinnipeds – sea lions, seals and walruses – are the only insects capable of surviving marine dives. Throughout their evolutionary history, they have adapted to tolerate hypoxia, high salinity, low temperature and, in particular, to tolerate conditions of high hydrostatic pressure. To understand the limits of the capacity of lice to survive during host deep dives, we conducted a series of controlled experiments in the laboratory. We collected lice from elephant seals and submitted the different life stages to high pressure conditions. Lice were first exposed to one of four hydrostatic pressures: 30, 80, 150 or 200 kg cm−2. They were then exposed a second time to higher or lower hydrostatic pressure conditions to test for the impact of the first experience, which could either be deleterious or trigger physiological adaption, allowing them a better tolerance to high pressure. We found that lice from elephant seals can tolerate hydrostatic pressures higher than 200 kg cm−2 (close to 200 atm), which is equivalent to 2000 m depth. Adults exhibited lower recovery times than nymphs after immersion at high hydrostatic pressure. Our findings show that lice have developed unique adaptations to endure extreme marine conditions. We discuss these extreme performances in relation to the morphological characteristics and physiological responses to diving in these insects.

“…In a previous study, we found that on average almost 60% of the elephant seals from 25 de Mayo/King George Island were infested with lice (Leonardi et al ., 2018). Both the prevalence and the mean intensity are higher in pups and juveniles than adults (Leonardi et al ., 2018). The high presence of this lice species on elephant seals has also an epidemiological significance.…”

Section: Figmentioning

confidence: 99%

“…Lepidophthirus macrorhini Enderlein infests southern elephant seals during their entire life cycle (Murray & Nicholls, 1965). In a previous study, we found that on average almost 60% of the elephant seals from 25 de Mayo/King George Island were infested with lice (Leonardi et al ., 2018). Both the prevalence and the mean intensity are higher in pups and juveniles than adults (Leonardi et al ., 2018).…”

Section: Figmentioning

confidence: 99%

I've got you under my skin: inflammatory response to elephant seal's lice

Krmpotic²,

Barbeito

et al. 2021

Medical Vet Entomology

Seals (Phocidae) undergo an annual cycle of moulting that implies hair regeneration, and in the case of southern elephant seals, it also involves the superficial strata of the epidermis. Therefore, surviving the moulting period is crucial for their obligate and permanent ectoparasites. Throughout evolutionary time, sucking lice (Echinophtiriidae) have developed morphological, behavioural and ecological adaptations to cope with the amphibious lifestyle of their hosts. Lepidophthirus macrorhini, the Southern elephant seal louse species, faces the additional challenge of surviving attached to the host during the moulting period. Since lice live on the skin, L. macrorhini has developed a unique survival strategy by piercing the skin of their host, thus keeping them protected from moulting. During fieldwork in Patagonia and Antarctica, skin samples with lice within were collected for histological analysis to assess whether these parasites caused damage to the host. Lice generate an inflammatory process in the host's dermis, and these lesions could alter the normal chemical and mechanical protective properties of the skin facilitating secondary infections. Further studies that analyse the potential pathogens in those skin lesions are necessary to properly assess the real impact of ectoparasites on their host health.