Parasite intensity drives fetal development and sex allocation in a wild ungulate

Altres ajuts: Natural Sciences and Engineering Research Council of Canada 316189-2012-RGPIN. Beringian Coevolution Project (BCP), National Science Foundation DEB 0196095 i 0415668An understanding of the mechanisms influencing prenatal characteristics is fundamental to comprehend the role of ecological and evolutionary processes behind survival and reproductive success in animals. Although the negative influence of parasites on host fitness is undisputable, we know very little about how parasitic infection in reproductive females might influence prenatal factors such as fetal development and sex allocation. Using an archival collection of Dall's sheep (Ovis dalli dalli), a capital breeder that depends on its body reserves to overcome the arctic winter, we investigated the direct and indirect impacts of the parasite community on fetal development and sex allocation. Using partial least squares modelling, we observed a negative effect of parasite community on fetal development, driven primarily by the nematode Marshallagia marshalli. Principal component analysis demonstrated that mothers with low parasite burden and in good body condition were more likely to have female versus male fetuses. This association was primarily driven by the indirect effect of M. marshalli on ewe body condition. Refining our knowledge of the direct and indirect impact that parasite communities can have on reproduction in mammals is critical for understanding the effects of infectious diseases on wildlife populations. This can be particularly relevant for species living in ecosystems sensitive to the effects of global climate change

Deep amplicon sequencing highlights low intra-host genetic variability of Echinococcus multilocularis and high prevalence of the European-type haplotypes in coyotes and red foxes in Alberta, Canada

Echinococcus multilocularis (Em) is a zoonotic parasite considered a global emergent pathogen. Recent findings indicate that the parasite is expanding its range in North America (NA) and that European-type (EU) haplotypes are circulating in western Canada. However, genetic analyses are usually conducted only on a few parasites out of thousands of individuals within each definitive host, likely underestimating the prevalence of less common haplotypes. Moreover, mixed infections with several mtDNA haplotypes in the same host have been reported, but their relative abundance within the host was never estimated. We aimed to 1) estimate the frequency of co-infections of different Em haplotypes in coyotes (Canis latrans) and red foxes (Vulpes vulpes) of western Canada and their relative abundance within the definitive hosts, 2) detect less prevalent haplotypes by sampling a larger proportion of the parasite subpopulation per host, and 3) investigate differences in the distribution of Em haplotypes in these main definitive hosts; foxes and coyotes. We extracted DNA from ~10% of the worm subpopulation per host (20 foxes and 47 coyotes) and used deep amplicon sequencing (NGS technology) on four loci, targeting the most polymorphic regions from the mitochondrial genes cox1 (814 bp), nad1 (344 bp), and cob (387 bp). We detected the presence of mixed infections with multiple Em haplotypes and with different Echinococcus species including E. granulosus s.l. genotypes G8/G10, low intraspecific diversity of Em, and a higher abundance of the EU-type haplotypes in both hosts. Our results suggest a population expansion of the European over the North American strain in Alberta and a limited distribution of some European-type haplotypes. Our findings indicate that deep amplicon sequencing represents a valuable tool to characterize Em in multiple hosts, to assess the current distribution and possible origins of the European strain in North America. The potential use of next-generation sequencing technologies is particularly important to understand the patterns of geographic expansion of this parasite

It’s a small world for parasites: evidence supporting the North American invasion of European Echinococcus multilocularis

Echinococcus multilocularis (Em), the causative agent of human alveolar echinococcosis (AE), is present in the Holarctic region as several genetic variants deemed to have differential infectivity and pathogenicity. An unprecedented outbreak of human AE cases in Western Canada infected with a European-like strain circulating in wild hosts warranted assessment of whether this strain was derived from a recent invasion or was endemic but undetected. Using nuclear and mitochondrial markers, we investigated the genetic diversity of Em in wild coyotes and red foxes from Western Canada, compared the genetic variants identified to global isolates, and assessed spatial distribution to infer possible invasion dynamics. Genetic variants from Western Canada were closely related to the original European clade, with lesser genetic diversity than that expected for a long-established strain and spatial genetic discontinuities within the study area, supporting the hypothesis of a relatively recent invasion with various founder events

Mother's occupation and sex ratio at birth

<p>Abstract</p> <p>Background</p> <p>Many women are working outside of the home, occupying a multitude of jobs with varying degrees of responsibilities and levels of psychological stress. We investigated whether different job types in women are associated with child sex at birth, with the hypothesis that women in job types, which are categorized as "high psychological stress" jobs, would be more likely to give birth to a daughter than a son, as females are less vulnerable to unfavourable conditions during conception, pregnancy and after parturition, and are less costly to carry to term.</p> <p>Methods</p> <p>We investigated the effects of mother's age, maternal and paternal job type (and associated psychological stress levels) and paternal income on sex ratio at birth. Our analyses were based on 16,384 incidences of birth from a six-year (2000 to 2005 inclusive) childbirth dataset from Addenbrooke's Hospital in Cambridge, UK. We obtained a restricted data set from Addenbrooke's hospital with: maternal age, maternal and paternal occupations, and whether or not the child was first-born.</p> <p>Results</p> <p>Women in job types that were categorized as "high stress" were more likely to give birth to daughters, whereas women in job types that were categorized as "low stress" had equal sex ratios or a slight male bias in offspring. We also investigated whether maternal age, and her partner's income could be associated with reversed offspring sex ratio. We found no association between mother's age, her partner's job stress category or partner income on child sex. However, there was an important interaction between job stress category and partner income in some of the analyses. Partner income appears to attenuate the association between maternal job stress and sex ratios at moderate-income levels, and reverse it at high-income levels.</p> <p>Conclusions</p> <p>To our knowledge this is the first report on the association between women's job type stress categories and offspring sex ratio in humans, and the potential mitigating effect of their partners' income.</p

Distribution, Population Size, and Structure of Himalayan Grey goral \u3cem\u3eNaemorhedus goral bedfordi\u3c/em\u3e (Cetartiodactyla: Bovidae) in Pakistan

Himalayan grey goral (Naemorhedus goral bedfordi) is a Red List (Near Threatened) member of Caprinae endemic to Asia, occupying the south-facing slopes of the Himalaya Mountains. The species is listed as Vulnerable on the National Pakistan Red List, but the distribution and abundance of the species within the nation is poorly known. We conducted a national census of Himalayan grey goral in Pakistan during 2002 – 2004, with the objective of documenting the geographic locations of populations, estimating population size, and describing group sizes and sex ratios. We conducted a direct count census in 98 sites distributed over the 4839 km2 of suitable grey goral habitat. We counted 172 unique grey goral individuals: 143 adults and 29 subadults. We estimated a minimum of 370 – 1017 grey goral in Pakistan distributed in seven isolated populations. The adult sex ratio was female-biased nearly 2:1, and the mean size of social groups was 1.72 ± 0.11 SE individuals. Our data support the National Red List status of Himalayan grey goral as Vulnerable, because no subpopulation probably contains \u3e 1000 individuals. We are unable to account for the sex ratio bias. Social group size is comparable with contemporary observations from India, but much lower than that reported a century ago. A national population viability analysis is needed for this species

Parasite removal improves reproductive success of female North American red squirrels (Tamiasciurus hudsonicus).

In order to evaluate potential reproductive costs associated with parasitism, we experimentally removed ectoparasites from reproductive female North American red squirrels (Tamiasciurus hudsonicus). Body mass and overwinter survival of mothers, days to juvenile emergence, juvenile survival from birth to emergence, and body mass of juveniles at emergence were all compared to those of untreated (control) animals. Ectoparasite removal did not affect the body mass of mothers throughout the lactation period and overwinter survival of mothers did not differ between treatments and controls. Likewise, there was no effect of treatment on the number of days to juvenile emergence. However, treated mothers raised offspring that were significantly heavier (11%) than controls at emergence. Juveniles from treated mothers were also 24% more likely to survive from birth to emergence. Our results indicate that ectoparasites impose costs on the reproductive success of female red squirrels and that ectoparasites have the potential to influence red squirrel life-histories and population dynamics

Patterns of ectoparasitism in North American red squirrels (Tamiasciurus hudsonicus): Sex-biases, seasonality, age, and effects on male body condition

Within many species, males are often more heavily parasitised than females. Several hypotheses have been proposed to explain this phenomenon, including immunocompetence handicaps, sexual size dimorphism and behavioural differences. Here we set out to test the latter two hypotheses and make inferences about the former by assessing patterns of ectoparasitism across various life-history stages in a population of North American red squirrels (Tamiasciurus hudsonicus). We also conducted an ectoparasite removal experiment to investigate the effects of ectoparasites on male body condition. We found that males were more intensely parasitized than females, but only during the mating period. There was no difference in ectoparasite intensity between male and female juveniles at birth or at emergence, suggesting that ectoparasites do not exploit male red squirrels for longer-range natal dispersal. Male red squirrels in our population were slightly heavier than females, however we did not find any evidence that this dimorphism drives male-biased ectoparasitism. Finally, we could not detect an effect of ectoparasite removal on male body mass. Our results lend support to the hypothesis that ectoparasites exploit their male hosts for transmission and that male red squirrels are important for the transmission dynamics of ectoparasites in this population; however, the mechanisms (i.e., immunocompetence, testosterone) are not known

Effects of intrinsic and extrinsic factors on ruminating, grazing, and bedding time in bighorn sheep (Ovis canadensis).

Rumination is the repeated process of regurgitation of a food bolus, followed by chewing, swallowing, and regurgitation, which enhance nutrient assimilation. Time spent in lateral recumbency (i.e., bedded, lying) has often been used as a proxy for time spent ruminating due to difficulties of observing detailed rumination behavior in the field. The actual proportion of time spent ruminating, or other activities, will in turn be affected by the age and sex of an individual but also with changes in food quality. We studied the effects of intrinsic and extrinsic factors on time spent ruminating, bedding, proportion of bedding time spent ruminating, and grazing of individually marked bighorn sheep (Ovis canadensis). Our results show that bighorn sheep spent more time ruminating and less time grazing in summer and autumn. Overall, females spent less time ruminating, and more time grazing than males. Bighorn sheep decreased their time spent ruminating with increasing acid detergent fiber (ADF) content in the forage. Age influenced the time spent grazing, bedded and proportion of bedded time spent ruminating. Older sheep not only increased their bedding time but also their time spent bedded without ruminating compared to younger individuals. The proportion of time spent grazing was also affected by age, with a decrease in the proportion of time spent grazing with increasing age. Our results suggest that these four behaviors are plastic and variable. We thus conclude that bedding time does not reflect time spent ruminating but that the latter is affected by both intrinsic and extrinsic factors

Seasonal and annual estimates of small mammals, overall and infected intermediate hosts (IHs) of <i>Echinococcus multilocularis</i> ingested by individual coyotes in Calgary, AB, Canada, between June 2012 and June 2013.

<p>^a Small mammals reported as susceptible hosts for <i>E</i>. <i>multilocularis</i> in North America [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0121646#pone.0121646.ref025" target="_blank">25</a>].</p><p>^b Daily defecation rate of coyotes (0.79 scats/day) [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0121646#pone.0121646.ref015" target="_blank">15</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0121646#pone.0121646.ref045" target="_blank">45</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0121646#pone.0121646.ref046" target="_blank">46</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0121646#pone.0121646.ref050" target="_blank">50</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0121646#pone.0121646.ref051" target="_blank">51</a>].</p><p>^c Seasonal prevalence (95% CI) of <i>E</i>. <i>multilocularis</i> in intermediate hosts in the study area [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0121646#pone.0121646.ref044" target="_blank">44</a>].\</p><p>Seasonal and annual estimates of small mammals, overall and infected intermediate hosts (IHs) of <i>Echinococcus multilocularis</i> ingested by individual coyotes in Calgary, AB, Canada, between June 2012 and June 2013.</p