scholarly journals The expression of virulence for a mixed-mode transmitted parasite in a diapausing host

Parasitology ◽  
2014 ◽  
Vol 141 (8) ◽  
pp. 1097-1107 ◽  
Author(s):  
ELHAM SHEIKH-JABBARI ◽  
MATTHEW D. HALL ◽  
FRIDA BEN-AMI ◽  
DIETER EBERT
Keyword(s):  
Hatching Success ◽  
Life Stage ◽  
Horizontal Transmission ◽  
Resting Eggs ◽  
Life Stages ◽  
Infected Female ◽  
Population Prevalence ◽  
High Virulence ◽  
Host Life ◽  
Adaptive Nature

SUMMARYMany parasites survive harsh periods together with their hosts. Without the possibility of horizontal transmission during host diapause, parasite persistence depends entirely on host survival. We therefore hypothesize that a parasite should be avirulent during its host's diapausing stage. In contrast, the parasite may express higher virulence, i.e. parasite-induced fitness reduction of the host, during host life stages with good opportunities for horizontal transmission. Here we study the effects of a vertically and horizontally transmitted microsporidium parasite, Hamiltosporidium tvaerminnensis, on the quantity and survival of resting eggs of its host Daphnia magna. We find that the parasite did not affect egg volume, hatching success and time to hatching of the Daphnia's resting eggs, although it did strongly reduce the number of resting eggs produced by infected females, revealing high virulence during the non-diapause phase of the host's life cycle. These results also explain another aspect of this system – namely the strong decline in natural population prevalence across diapause. This decline is not caused by mortality in infected resting stages, as was previously hypothesized, but because infected female hosts produce lower rates of resting eggs. Together, these results help explain the epidemiological dynamics of a microsporidian disease and highlight the adaptive nature of life stage-dependent parasite virulence.

scholarly journals Abundance, placement and sexual identity of the epizoic barnacle Chelonibia testudinaria relative to the size and species of host turtles in Mabul Island, Malaysia

2020 ◽  
Vol 100 (8) ◽  
pp. 1299-1309
Author(s):  
Kah Kheng Lim ◽  
Muhammad Ali Syed Hussein ◽  
Pushpa Palaniappan
Keyword(s):  
Sea Turtles ◽  
Life Stage ◽  
Chelonia Mydas ◽  
Life Stages ◽  
Adult Males ◽  
Shell Size ◽  
Marine Fauna ◽  
Eretmochelys Imbricata ◽  
Acorn Barnacle ◽  
Host Life

AbstractSea turtles are partners in commensal relationships with a variety of epibionts, including barnacles. The acorn barnacle Chelonibia testudinaria is one species commonly found associated with sea turtles and other marine fauna throughout temperate to tropical waters including the Indo-Pacific. We conducted a study to assess the occurrence of this barnacle, relative to host life stage and species in a mixed foraging population of green (Chelonia mydas) and hawksbill (Eretmochelys imbricata) turtles (juvenile, sub-adult, adults (female and male)) in Mabul Island, Sabah, Malaysia (Celebes Sea). Expecting similar relative abundance by life stage, we found instead a significant effect between the combined dependent variables (abundance and size of barnacles) and the life stages of sea turtles in Mabul after controlling for the covariates of size and species of sea turtles (F(8, 428) = 5.77, P < 0.001, Pillai = 0.19). Among green turtles with barnacles, though adult males had larger barnacles compared with the female turtles, the mean barnacle abundance on adult females (43.4 individuals ± 5.19 SD) was higher than all other life stages. Most of the barnacles (85.6%; N = 1931) were found on the plastron of the sea turtles. The highest number of barnacle reacquisition was found among the juvenile turtles. In assessing the complemental males of the barnacles, we found they were consistently attached to the shells of the larger of the hermaphrodites from each region of the host's body despite average shell-size differences with each region.

‘And all my children?’

2018 ◽  
Author(s):  
Charlotte Scott
Keyword(s):  
Early Modern ◽  
Life Stage ◽  
Early Modern Period ◽  
Life Stages ◽  
Cultural Imagination ◽  
Modern Period

Beginning with an exploration of the role of the child in the cultural imagination, Chapter 1 establishes the formative and revealing ways in which societies identify themselves in relation to how they treat their children. Focusing on Shakespeare and the early modern period, Chapter 1 sets out to determine the emotional, symbolic, and political registers through which children are depicted and discussed. Attending to the different life stages and representations of the child on stage, this chapter sets out the terms of the book’s enquiry: what role do children play in Shakespeare’s plays; how do we recognize them as such—age, status, parental dynamic—and what are the effects of their presence? This chapter focuses on how the early moderns understood the child, as a symbolic figure, a life stage, a form of obligation, a profound bond, and an image of servitude.

scholarly journals Variación en la abundancia de árboles maderables por efecto de borde en un bosque tropical subcaducifolio

2019 ◽  
Vol 97 (1) ◽  
pp. 35 ◽  
Author(s):  
Víctor Abraham Vargas-Vázquez ◽  
Crystian Sadiel Venegas-Barrera ◽  
Arturo Mora-Olivo ◽  
José Guadalupe Martínez-Ávalos ◽  
Eduardo Alanís-Rodríguez ◽  
...  
Keyword(s):  
Edge Effect ◽  
Environmental Conditions ◽  
Life Stage ◽  
Life Stages ◽  
Cedrela Odorata ◽  
Economic Implications ◽  
Bursera Simaruba ◽  
Environmental Requirements ◽  
Guazuma Ulmifolia ◽  
Favorable Conditions

<p><strong>Background: </strong>The edge effect differentially affects the species in their life stages. We analyzed the environmental conditions associated with the abundance by life stage of four species of timber trees on the edge of a subdeciduous tropical forest.<strong></strong></p><p><strong>Hypothesis:</strong> The edges have higher light incidence and temperature, favorable conditions for the seedlings, so it is expected that the edge will have more abundance of seedlings with respect to the forest interior.</p><p><strong>Species under study:</strong> <em>Bursera simaruba</em> (L.) Sarg.<em>, Cedrela odorata</em> L.<em>, Guazuma ulmifolia </em>Lam.<em>, Lysiloma divaricatum </em>(Jacq.) J.F. Macbr.</p><p><strong>Study site and dates:</strong> Reserva de la Biosfera "El Cielo" (Tamaulipas), Mexico. January-December 2016.</p><p><strong>Methods: </strong>The abundance by life stages and environmental conditions were quantified within the gradient. These variables were correlated, in addition the requirements between stages were contrasted and they were associated with the identified environments.</p><p><strong>Results:</strong> <em>Guazuma ulmifolia</em> showed a negative response to the edge effect, while <em>Cedrela</em> <em>odorata</em> responded positively. The environmental requirements differed between the first life stages and adults. The abundance of the seedlings was associated to conditions of higher light incidence.</p><strong>Conclusions:</strong> Environmental requirements differentially affect each life stage. The abundance of seedlings increases in conditions of higher light incidence, but not in the rest of the stages, except in <em>C. odorata</em>. The loss of cover and the consequent formation of borders can lead to a reduction in the abundance of these species, with economic implications.

scholarly journals Bile acid production is life-stage and sex-dependent and affected by primer pheromones in the sea lamprey

2021 ◽  
pp. jeb.229476
Author(s):  
Yu-Wen Chung-Davidson ◽  
Ugo Bussy ◽  
Skye D. Fissette ◽  
Anne M. Scott ◽  
Weiming Li
Keyword(s):  
Bile Salt ◽  
Bile Salts ◽  
Life Stage ◽  
Sea Lamprey ◽  
Life Stages ◽  
Pheromone Production ◽  
Primer Pheromone ◽  
Petromyzonol Sulfate ◽  
Sea Lampreys ◽  
Primer Pheromones

Pheromonal bile salts are important for sea lampreys (Petromyzon marinus Linnaeus) to complete their life cycle. The synthesis and release of a releaser/primer pheromone 3-keto petromyzonol sulfate (3kPZS) by spermiating males have been well characterized. 3kPZS evokes sexual behaviors in ovulatory females, induces immediate 3kPZS release in spermiating males, and elicits neuroendocrine responses in prespawning adults. Another primer pheromone released by spermiating males, 3-keto allocholic acid (3kACA), antagonizes the neuroendocrine effects of 3kPZS in prespermiating males. However, the effects of 3kACA and 3kPZS on pheromone production in prespawning adults is unclear. To understand the foundation of pheromone production, we examined sea lamprey bile salt levels at different life stages. To investigate the priming effects of 3kACA and 3kPZS, we exposed prespawning adults with vehicle or synthetic 3kACA or 3kPZS. We hypothesized that endogenous bile salt levels were life-stage and sex-dependent, and differentially affected by 3kACA and 3kPZS in prespawning adults. Using ultra-performance liquid chromatography tandem mass spectrometry, we found that sea lampreys contained distinct mixtures of bile salts in the liver and plasma at different life stages. Males usually contained higher amounts of bile salts than females. Petromyzonamine disulfate was the most abundant C27 bile salt and petromyzonol sulfate was the most abundant C24 bile salt. Waterborne 3kACA and 3kPZS exerted differential effects on bile salt production in the liver and gill, their circulation and clearance in the plasma, and their release into water. We conclude that bile salt levels are life-stage and sex-dependent and differentially affected by primer pheromones.

scholarly journals What wild dogs want: habitat selection differs across life stages and orders of selection in a wide-ranging carnivore

BMC Zoology ◽  
2020 ◽  
Vol 5 (1) ◽  
Author(s):  
Helen M. K. O’Neill ◽  
Sarah M. Durant ◽  
Rosie Woodroffe
Keyword(s):  
Habitat Selection ◽  
Human Population ◽  
Life Stage ◽  
Selection Function ◽  
Order Selection ◽  
Life Stages ◽  
Population Densities ◽  
Selection For ◽  
Wild Dogs ◽  
Selection Of

Abstract Background Habitat loss is a key threat to the survival of many species. Habitat selection studies provide key information for conservation initiatives by identifying important habitat and anthropogenic characteristics influencing the distribution of threatened species in changing landscapes. However, assumptions about the homogeneity of individual choices on habitat, regardless of life stage, are likely to result in inaccurate assessment of conservation priorities. This study addresses a knowledge gap in how animals at different life stages diverge in how they select habitat and anthropogenic features, using a free-ranging population of African wild dogs living in a human-dominated landscape in Kenya as a case study. Using GPS collar data to develop resource selection function and step selection function models, this study investigated differences between second order (selection of home range across a landscape) and third order (selection of habitat within the home range) habitat selection across four life history stages when resource requirements may vary: resident-non-denning, resident-heavily-pregnant, resident-denning and dispersing. Results Wild dogs showed strong second order selection for areas with low human population densities and areas close to rivers and roads. More rugged areas were also generally selected, as were areas with lower percentage tree cover. The strength of selection for habitat variables varied significantly between life stages; for example, dispersal groups were more tolerant of higher human population densities, whereas denning and pregnant packs were least tolerant of such areas. Conclusions Habitat selection patterns varied between individuals at different life stages and at different orders of selection. These analyses showed that denning packs and dispersal groups, the two pivotal life stages which drive wild dog population dynamics, exhibited different habitat selection to resident-non-breeding packs. Dispersal groups were relatively tolerant of higher human population densities whereas denning packs preferred rugged, remote areas. Evaluating different orders of selection was important as the above trends may not be detectable at all levels of selection for all habitat characteristics. Our analyses demonstrate that when life stage information is included in analyses across different orders of selection, it improves our understanding of how animals use their landscapes, thus providing important insights to aid conservation planning.

scholarly journals Survey of bacteria associated with western corn rootworm life stages reveals no difference between insects reared in different soils

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Dalton C. Ludwick ◽  
Aaron C. Ericsson ◽  
Lisa N. Meihls ◽  
Michelle L. J. Gregory ◽  
Deborah L. Finke ◽  
...  
Keyword(s):  
Pest Management ◽  
Life Stage ◽  
Management Strategies ◽  
Diabrotica Virgifera Virgifera ◽  
Western Corn Rootworm ◽  
16S Rrna Genes ◽  
Rrna Genes ◽  
Corn Rootworm ◽  
Life Stages ◽  
Different Soils

Abstract Western corn rootworm (Diabrotica virgifera virgifera LeConte) is a serious pest of maize (Zea mays L.) in North America and parts of Europe. With most of its life cycle spent in the soil feeding on maize root tissues, this insect is likely to encounter and interact with a wide range of soil and rhizosphere microbes. Our knowledge of the role of microbes in pest management and plant health remains woefully incomplete, yet that knowledge could play an important role in effective pest management strategies. For this study, insects were reared on maize in soils from different locations. Insects from two different laboratory colonies (a diapausing and a non-diapausing colony) were sampled at each life stage to determine the possible core bacteriome. Additionally, soil was sampled at each life stage and resulting bacteria were identified to determine the possible contribution of soil to the rootworm bacteriome, if any. We analyzed the V4 hypervariable region of bacterial 16S rRNA genes with Illumina MiSeq to survey the different species of bacteria associated with the insects and the soils. The bacterial community associated with insects was significantly different from that in the soil. Some differences appear to exist between insects from non-diapausing and diapausing colonies while no significant differences in community composition existed between the insects reared on different soils. Despite differences in the bacteria present in immature stages and in male and female adults, there is a possible core bacteriome of approximately 16 operational taxonomic units (i.e., present across all life stages). This research may provide insights into Bt resistance development, improved nutrition in artificial rearing systems, and new management strategies.

scholarly journals Effects of Life Stage, Site, and Species on the Dragonfly Gut Microbiome

2020 ◽  
Vol 8 (2) ◽  
pp. 183 ◽  
Author(s):  
Sarah Nobles ◽  
Colin R. Jackson
Keyword(s):  
Gut Microbiome ◽  
Host Species ◽  
Life Stage ◽  
Rrna Gene ◽  
Life Stages ◽  
Aquatic Habitats ◽  
Surrounding Environment ◽  
Different Levels ◽  
Generation Sequencing ◽  
Bacterial 16S Rrna Gene

Insects that undergo metamorphosis from juveniles to adults provide an intriguing opportunity to examine the effects of life stage, species, and the environment on their gut microbiome. In this study, we surveyed the gut microbiomes of 13 species of dragonfly collected from five different locations subject to different levels of human impact. Juveniles were collected as nymphs from aquatic habitats while airborne adults were caught at the same locations. The gut microbiome was characterized by next generation sequencing of the bacterial 16S rRNA gene. Life stage was an important factor, with the gut microbiomes of dragonfly nymphs differing from those of adult dragonflies. Gut microbiomes of nymphs were influenced by sample site and, to a lesser extent, host species. Neither sample location nor host species had a strong effect on the gut microbiome of dragonfly adults. Regardless of life stage, gut microbiomes were dominated by members of the Proteobacteria, with members of the Bacteroidetes (especially in adults), Firmicutes, and Acidobacteria (especially in nymphs) also being proportionally abundant. These results demonstrate that different life stages of metamorphosing insects can harbor very different gut microbiomes and differ in how this microbiome is influenced by the surrounding environment.

scholarly journals Thermal performance curves reveal shifts in optima, limits and breadth in early life

2020 ◽  
Vol 223 (22) ◽  
pp. jeb233254
Author(s):  
Adriana P. Rebolledo ◽  
Carla M. Sgrò ◽  
Keyne Monro
Keyword(s):  
Embryo Development ◽  
Thermal Performance ◽  
Early Life ◽  
Thermal Sensitivity ◽  
Life Stage ◽  
Life Stages ◽  
Parametric Bootstrapping ◽  
Performance Curves ◽  
Survival And Reproduction ◽  
Mixed Modelling

ABSTRACTUnderstanding thermal performance at life stages that limit persistence is necessary to predict responses to climate change, especially for ectotherms whose fitness (survival and reproduction) depends on environmental temperature. Ectotherms often undergo stage-specific changes in size, complexity and duration that are predicted to modify thermal performance. Yet performance is mostly explored for adults, while performance at earlier stages that typically limit persistence remains poorly understood. Here, we experimentally isolate thermal performance curves at fertilization, embryo development and larval development stages in an aquatic ectotherm whose early planktonic stages (gametes, embryos and larvae) govern adult abundances and dynamics. Unlike previous studies based on short-term exposures, responses with unclear links to fitness or proxies in lieu of explicit curve descriptors (thermal optima, limits and breadth), we measured performance as successful completion of each stage after exposure throughout, and at temperatures that explicitly capture curve descriptors at all stages. Formal comparisons of descriptors using a combination of generalized linear mixed modelling and parametric bootstrapping reveal important differences among life stages. Thermal performance differs significantly from fertilization to embryo development (with thermal optimum declining by ∼2°C, thermal limits shifting inwards by ∼8–10°C and thermal breadth narrowing by ∼10°C), while performance declines independently of temperature thereafter. Our comparisons show that thermal performance at one life stage can misrepresent performance at others, and point to gains in complexity during embryogenesis, rather than subsequent gains in size or duration of exposure, as a key driver of thermal sensitivity in early life.

scholarly journals Reducing bias in population and landscape genetic inferences: the effects of sampling related individuals and multiple life stages

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e1813 ◽  
Author(s):  
William Peterman ◽  
Emily R. Brocato ◽  
Raymond D. Semlitsch ◽  
Lori S. Eggert
Keyword(s):  
Best Practice ◽  
Isolation By Distance ◽  
Life Stage ◽  
Population Sample ◽  
Life Stages ◽  
Effective Population ◽  
Data Set ◽  
Sibling Pairs ◽  
Population Sizes ◽  
Landscape Genetic

In population or landscape genetics studies, an unbiased sampling scheme is essential for generating accurate results, but logistics may lead to deviations from the sample design. Such deviations may come in the form of sampling multiple life stages. Presently, it is largely unknown what effect sampling different life stages can have on population or landscape genetic inference, or how mixing life stages can affect the parameters being measured. Additionally, the removal of siblings from a data set is considered best-practice, but direct comparisons of inferences made with and without siblings are limited. In this study, we sampled embryos, larvae, and adultAmbystoma maculatumfrom five ponds in Missouri, and analyzed them at 15 microsatellite loci. We calculated allelic richness, heterozygosity and effective population sizes for each life stage at each pond and tested for genetic differentiation (FSTandDC) and isolation-by-distance (IBD) among ponds. We tested for differences in each of these measures between life stages, and in a pooled population of all life stages. All calculations were done with and without sibling pairs to assess the effect of sibling removal. We also assessed the effect of reducing the number of microsatellites used to make inference. No statistically significant differences were found among ponds or life stages for any of the population genetic measures, but patterns of IBD differed among life stages. There was significant IBD when using adult samples, but tests using embryos, larvae, or a combination of the three life stages were not significant. We found that increasing the ratio of larval or embryo samples in the analysis of genetic distance weakened the IBD relationship, and when usingDC, the IBD was no longer significant when larvae and embryos exceeded 60% of the population sample. Further, power to detect an IBD relationship was reduced when fewer microsatellites were used in the analysis.

Sign in / Sign up

Export Citation Format

Share Document