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opencc-zeroSep 2020View details →

Life history genomic regions explain differences in Atlantic salmon marine diet specialization

Abstract 1. Animals employ various foraging strategies along their ontogeny to acquire energy, and with varying degree of efficiencies, to support growth, maturation and subsequent reproduction events. Individuals that can efficiently acquire energy early are more likely to mature at an earlier age, as a result of faster energy gain which can fuel maturation and reproduction. 2. We aimed to test the hypothesis that heritable resource acquisition variation that co-varies with efficiency along the ontogeny would influence maturation timing of individuals. 3. To test this hypothesis, we utilized Atlantic salmon as a model which exhibit a simple, hence trackable, genetic control of maturation age. We then monitored the variation in diet acquisition (quantified as stomach fullness and composition) of individuals with different ages, and linked it with genomic regions (haploblocks) that were previously identified to be associated with age-at-maturity. 4. Consistent with the hypothesis, we demonstrated that one of the life history genomic regions tested six(6) was indeed associated with age-dependent differences in stomach fullness. Prey composition was marginally linked to six(6), and suggestively (but non-significantly) to vgll3 genomic regions. We further showed Atlantic salmon switched to the so-called "feast and famine" strategy along the ontogeny, where older age groups exhibited heavier stomach content, but that came at the expense of running on empty more often. 5. These results suggest genetic variation underlying resource utilization may explain the genetic basis of age structure in Atlantic salmon. Given that ontogenetic diet has a genetic component and the strong spatial diversity associated with these genomic regions, we predict populations with diverse maturation age will have diverse evolutionary responses to future changes in marine food-web structures. 28-Jul-2020

opencc-zeroSep 2020View details →

Data from: Experimental migration upward in elevation is associated with strong selection on life history traits

One of the strongest biological impacts of climate change has been the movement of species poleward and upward in elevation. Yet, what is not clear, is the extent to which the spatial distribution of locally adapted lineages and ecologically important traits may also shift with continued climate change. Here, we take advantage of a transplant experiment mimicking up-slope seed dispersal for a suite of ecologically-diverse populations of yellow monkeyflower (Mimulus guttatus sensu lato) into a high-elevation common garden during an extreme drought period in the Sierra Nevada mountains, California, USA. We use a demographic approach to quantify fitness and test for selection on life history traits in local vs. lower-elevation populations and in normal vs. drought years to test the potential for up-slope migration and phenotypic selection to alter the distribution of key life history traits in montane environments. We find that lower-elevation populations tend to outperform local populations, confirming the potential for up-slope migration. Although selection generally favored some local montane traits, including larger flowers and larger stem size at flowering, drought conditions tended to select for earlier flowering typical of lower elevation genotypes. Taken together, this suggests that monkeyflower lineages moving upward in elevation could experience selection for novel trait combinations, particularly under warmer and drier conditions that are predicted to occur with continued climate change.

opencc-zeroSep 2020View details →

Data from: Demography, life history trade-offs, and the gastrointestinal virome of wild chimpanzees

In humans, senescence increases susceptibility to viral infection. However, comparative data on viral infection in free-living non-human primates—even in our closest living relatives, chimpanzees and bonobos (Pan troglodytes and P. paniscus)—are relatively scarce, thereby constraining an evolutionary understanding of age-related patterns of viral infection. We investigated a population of wild eastern chimpanzees (P. t. schweinfurthii), using metagenomics to characterize viromes (full viral communities) in the feces of 42 sexually mature chimpanzees (22 males, 20 females) from the Kanyawara and Ngogo communities in Kibale National Park, Uganda. We identified 12 viruses from at least four families with genomes of both single-stranded RNA and single-stranded DNA. Although fecal viromes of both sexes varied with chimpanzee age, viral richness increased with age in males but not in females. This effect was largely due to three viruses, salivirus, porprismacovirus, and chimpanzee stool-associated RNA virus (chisavirus), which occurred more frequently in samples from older males. This finding is consistent with the hypothesis that selection on males for early-life reproduction compromises investment in somatic maintenance, which has delayed consequences for health later in life, in this case reflected in viral infection and/or shedding. Fecal viromes may be useful for studying processes related to the divergent reproductive strategies of males and females, aging, and sex differences in longevity.

opencc-zeroOct 2020View details →

Data from: Invasive lumbricid earthworms in North America – different life-histories but common dispersal?

Aim Lumbricid earthworms are invasive across northern North America, causing notable changes in forest ecosystems. During their range expansion, they encountered harsher climatic conditions compared to their native ranges in short time (~400 years). This study investigated if (1) dispersal barriers, (2) climatic selection, or (3) anthropogenic activities, i.e. fishing bait disposal, structure the dispersal of free-living earthworm populations. Location North America, forest habitats along former Wisconsinan glaciation line Taxon Lumbricus terrestris, L. rubellus Methods Lumbricus terrestris and L. rubellus co-occur in the same habitats but differ in ecology and use as fishing bait. Both species were sampled in five transects ranging from the east to the west coast of northern North America, including major dispersal barriers, three different climate zones, and bait shops near sampling locations. Genetic diversity and structure were compared between the two species, and the presence of free-living bait shop genotypes was assessed using four markers (COI, 16S rDNA, 12S rDNA, H3). Results Populations of both species were genetically diverse with some geographic structure, which was more pronounced in L. terrestris than in L. rubellus. Common haplotypes were present in all regions, but locally restricted haplotypes also occurred. Further, two distinct genetic clades of L. terrestris co-occurred only in the two most distant transects (Alberta and Minnesota). Genotypes identical to bait individuals were omnipresent in field populations of L. terrestris. Main conclusions Genetic diversity was high in both species, and invasive populations represented a genetic subset of European earthworms. Geographic and climatic dispersal barriers affected the less mobile species, L. rubellus, resulting in differences in genetic structure between the two species. Our results indicate common long-distance dispersal vectors and vectors affecting only L. terrestris. The roles of climate and anthropogenic activities are discussed, providing additional explanations of dispersal and new insights into establishment of invasive earthworm populations. Keywords biological invasion, colonisation, genetic clades, agriculture, climate, dispersal barriers

opencc-zeroDec 2019View details →

Parasite infestation influences life-history but not boldness behavior in placental live-bearing fish

Parasites can negatively affect the reproductive success of hosts. Placental species may be particularly susceptible, because parasite-induced stress during pregnancy could potentially influence embryo development. Here we examine the consequences of a trematode infestation (black spot disease, BSD) for fetal development and adult behavior in 19 natural populations of the placental live-bearing fish species Poeciliopsis retropinna (Poeciliidae) in Costa Rica. First, we observed substantial variation in parasite infestation among populations which correlated with a number of local environmental conditions (elevation, river width, depth, and flow velocity). Furthermore, we observed substantial variation in parasite infestation among females within populations associated with maternal age and size. We found that the infestation rate significantly influenced embryonic development, with more heavily parasitized females producing smaller and worse-conditioned offspring at birth, possibly because a costly immune response during pregnancy limits, either directly or indirectly, nourishment to developing embryos. Finally, a behavioral experiment in the field showed that the infestation rate did not affect an individual's boldness. Our study indicates that in placental live-bearing fish parasite infestation leads to reduced embryo provisioning during pregnancy, resulting in a smaller offspring size and quality at birth potentially with negative implications for offspring fitness.

opencc-zeroOct 2020View details →

Spatial connectedness imposes local- and metapopulation-level selection on life history through feedbacks on demography

Dispersal evolution impacts the fluxes of individuals and hence, connectivity in metapopulations. Connectivity is therefore decoupled from the structural connectedness of the patches within the spatial network. Because of demographic feedbacks, local selection also drives the evolution of other life history traits. We investigated how different levels of connectedness affect trait evolution in experimental metapopulations of the two-spotted spider mite. We separated local- and metapopulation-level selection and linked trait divergence to population dynamics.

opencc-zeroNov 2020View details →

Seasonal time constraints shape life history, physiology and behaviour independently, and decouple a behavioural syndrome in a damselfly

The integration of traits into 'syndromes' has been suggested as a useful framework to advance insights in trait responses to environmental stressors. Yet, how stressors shape the consistency ('repeatability') of traits and their covariation at the individual level remains debated. We studied how seasonal time constraints shape trait repeatability and integration of life-history, behavioural, and physiological traits along a fast-slow continuum, using the 'pace-of-life syndrome' as a framework. We manipulated the photoperiod during the larval development of the damselfly Ischnura elegans, generating a time-relaxed early, a control, and a time-constrained late group. The photoperiod treatment did not seem to affect the voltinism of the larvae. As predicted, late-period larvae accelerated development and growth, yet this acceleration was no longer detectable for growth and metabolic rate during the final instar, possibly due to costs of the initial life-history acceleration. This warrants caution when inferring a species' pace-of-life based on a specific developmental stage. The late-period larvae were as predicted more active (only during the later stages of the final instar) and bolder than the control larvae, but not different from the early-period larvae. Most studies on time constraints only compared late and control animals, thereby potentially wrongly concluding adaptive responses to time constraints. Activity, boldness, and body mass were repeatable, while growth and metabolic rates were not. Notably, repeatabilities did not change under time constraints. There was no support for an overall trait integration in a pace-of-life syndrome, yet activity and boldness covaried positively as expected. Importantly, this 'behavioural syndrome' was decoupled in the late-period larvae, which might be adaptive to enhance energy acquisition to fuel the accelerated development rate. Our results suggest that besides the predicted plastic acceleration of life-history, plastic changes in behavioural trait integration may also be an important but overlooked adaptive aspect of responding to time constraints.

opencc-zeroNov 2020View details →

A large wild salmon stock shows genetic and life history differentiation within, but not between, rivers

Anadromous salmonid fishes frequently exhibit strong geographic population structuring. However, population genetic differentiation of Atlantic salmon (Salmo salar) at fine geographic scales differs across equivalent spatial extents in different regions. So far, fine-scale genetic differentiation has not been assessed in rivers of the Baltic Sea, a region that contains an evolutionarily distinct Atlantic salmon lineage. Thus, Baltic salmon are currently managed on the river level, without focus on potential genetic structure and diversity within rivers. Here, we used microsatellites to characterize the genetic structure of wild juvenile salmon sampled throughout the interconnected, northern Baltic Tornio and Kalix Rivers. We found genetic differentiation within the two rivers, but not between them: salmon in the upper reaches differed from individuals in the lower reaches, regardless of river system. Further, examining smolts migrating from the river to the sea and adults returning from the sea to spawn, we found an association between the genetic structure and seasonal migration timing. Out-migrating smolts genetically assigned to upper river reaches were older and tended to reach the sea later in the season than smolts from the lower reaches. In contrast, mature adults originating from the upper reaches returned to the river early in the season. Our observation of genetic population structuring between downstream and upstream reaches of the large Tornio and Kalix rivers, and its association with migration timing, implies that careful temporal management of the northern Baltic fisheries would help to preserve the diversity and sustainability of the wild salmon stocks of these rivers.

Novel digital assessment technique used to describe peanut nodulation life history

Biological nitrogen fixation (BNF) in legume root nodules is an important source of N globally. Typically, the quantification of BNF is an estimate of N fixation through techniques such as an acetylene reduction assay or isotopic signatures. However, these methods have large logistical limitations, and do not allow for assessments of the nodule morphology or the nodulation process itself, knowledge that is important to fully understand the BNF process. To provide an updated method of nodulation assessments, peanut (Arachis hypogaea L.) nodules were sampled from a two-year field trial and quantified using scanned images of excised nodules, allowing digital assessment of nodule number and size. Further, a digital color analysis method was developed to assess internal nodule color (a known proxy for nodule BNF activity and senescence). To apply and validate the new method, peanut nodulation trait data was used for an exploration of the relationship between nodulation traits, plant physiological processes, and nitrogen status in the plant, followed by a nodulation life history analysis. The nodulation assessment method was validated by strong correlation with measures of peanut tissue N, biomass, photosynthetic function, and yield. Nodulation life history data suggest novel findings regarding differences in the development of nodules between taproots and lateral roots, contrary to the previous understanding of peanut nodulation life history. This new nodulation assessment method can provide further insight into the BNF process by allowing the collection of detailed data in a relatively simplified manner in field conditions. This dataset represents the nodulation and other variable data collected for this study.

Data from: Life-history dimensions indicate non-random assembly processes in tropical island tree communities

Community assembly processes on islands are often non-random. The mechanisms behind non-random assembly, however, are generally difficult to disentangle. Functional diversity in combination with a null model approach that accounts for differences in species richness among islands can be used to test for non-random assembly processes, but has been applied rarely to island communities. By linking functional diversity of trees on islands with a null model approach, we bridge this gap and test for the role of stochastic vs. non-random trait-mediated assembly processes in shaping communities by studying functional diversity-area relationships. We measured 11 plant functional traits linked to species dispersal and resource acquisition strategies of 57 tree species on 40 tropical islands. We grouped traits into four life-history dimensions representing (i) dispersal ability, (ii) growth strategy, (iii) light acquisition, and (iv) nutrient acquisition. To test for non-random assembly processes, we used null models that account for differences in species richness among the islands. Our results reveal contrasting responses of the four life-history dimensions to island area. The dispersal and the growth strategy dimensions were underdispersed on smaller islands, whereas the light acquisition dimension was overdispersed. The nutrient acquisition dimension did not deviate from null expectations. With increasing island area, shifts in the strength of non-random assembly processes increased the diversity of dispersal and acquisition strategies in island communities. Our results suggest that smaller islands may be more difficult to colonize and provide more limited niche space compared to larger islands, whose tree communities are likely determined by stochastic processes and higher niche diversity. Our null model approach highlights that analysing the functional diversity of different life-history dimensions provides a powerful framework to unravel community assembly processes on islands. These complex, non-random assembly processes are masked by measures of functional diversity that do not account for differences in species richness between islands.

Selection and plasticity both account for inter-annual variation in life-history phenology in an annual prairie legume

As the environment changes, so too must plant communities and populations if they are to persist. Life-history transitions and their timing are often the traits that are most responsive to changing environmental conditions. To compare the contributions of plasticity and natural selective response to variation in germination and flowering phenology, we performed a quantitative genetic study of phenotypic selection on Chamaecrista fasciculata (Fabaceae) across two consecutive years in a restored tallgrass prairie. The earliest dates of germination and flowering were recorded for two parental cohorts and one progeny cohort in an experimental garden. Environmental differences between years were the largest contributors to phenological variation in this population. In addition, there was substantial heritability for flowering time and statistically significant selection for advancement of flowering. Comparison between a progeny cohort its pre-selection parental cohort indicated a change in mean flowering time consistent with the direction of selection. Selection on germination time was weaker than that on flowering time, while environmental effects on germination time were stronger. The response to selection on flowering time was detectable when accounting for the effect of the environment on phenotypic differences, highlighting the importance of controlling for year-to-year environmental variation in quantitative genetic studies.

Fitness consequences of seasonally different life histories? A match-mismatch experiment

To survive and reproduce successfully, animals have to find the optimal time of breeding. Species living in non-tropical environments often adjust their reproduction plastically according to seasonal changes of the environment. Information about the prevailing season can be transmitted in utero, leading to adaptation of the offspring to the prevailing season. After birth, animals acquire additional personal information about the environment which allows them to adjust their reproductive investment. Here, we tested in a full-factorial match-mismatch experiment the influence of reproductive adjustments according to maternal and personal information. We bred wild cavies (Cavia aperea), a precocial rodent, either into increasing (spring) or decreasing (autumn) photoperiod and subsequently, after weaning, transferred female offspring to the matching or mismatching season. We measured growth, specific metabolic rate (sRMR) and reproductive events across six months. Although sRMR was elevated for females primed for good (spring) conditions when transferred to the mismatching autumn condition, we found no maternal effects on reproduction. Females adjusted their reproductive decisions according to the season they personally experienced, thereby implying a potentially high level of plasticity. Females reproducing in spring started reproduction earlier with a lower reproductive effort than females reproducing in autumn but ultimately, the two groups did not differ in survival, growth or reproduction. These data suggest important developmental plasticity, highlight the use of personal information acquired after weaning over early information provided until weaning and point out the potential value of multiple cues such as food abundance and quality and temperature besides photoperiod.

Data from: An identification of invariants in life history traits of amphibians and reptiles

While many morphological, physiological, and ecological characteristics of organisms scale with body size, some do not change under size transformation. They are called invariant. A recent study recommended five criteria for identifying invariant traits. These are based on that a trait exhibits a unimodal central tendency and varies over a limited range with body mass (type I), or that it does not vary systematically with body mass (type II). We methodologically improved these criteria and then applied them to life history traits of amphibians, Anura, Caudata (eleven traits), and reptiles (eight traits). The numbers of invariant traits identified by criteria differed across amphibian orders and between amphibians and reptiles. Reproductive output (maximum number of reproductive events per year), incubation time, length of larval period, and metamorphosis size were type I and II invariant across amphibians. In both amphibian orders, reproductive output and metamorphosis size were type I and II invariant. In Anura, incubation time and length of larval period and in Caudata, incubation time were further type II invariant. In reptiles, however, only number of clutches per year was invariant (type II). All these differences could reflect that in reptiles body size and in amphibians, Anura, and Caudata metamorphosis (neotenic species go not through it) and the trend towards independence of egg and larval development from water additionally constrained life history evolution. We further demonstrate that all invariance criteria worked for amphibian and reptilian life history traits, although we corroborated some known and identified new limitations to their application.

Life history evolution, species differences and phenotypic plasticity in hemiparasitic eyebrights (Euphrasia)

Premise of the study: Species delimitation in parasitic organisms is challenging as traits used in the identification of species are often plastic and vary depending on the host. Here, we use species from a recent radiation of generalist hemiparasitic Euphrasia to investigate trait variation and trait plasticity. We test whether Euphrasia species show reliable trait differences, investigate whether these differences correspond to life history trade-offs between growth and reproduction, and quantify plasticity in response to host species. Methods: We perform common garden experiments to evaluate trait differences between eleven Euphrasia taxa grown on a common host, document phenotypic plasticity when a single Euphrasia species is grown on eight different hosts, and relate our observations to trait differences recorded in the wild. Key results: Euphrasia exhibit variation in life history strategies; some individuals transition rapidly to flower at the expense of early season growth, while others invest in vegetative growth and delay flowering. Life history differences are present between some species, though many related taxa lack clear-cut trait differences. Species differences are further blurred by phenotypic plasticity—many traits are plastic and change with host type or between environments. Conclusions: Phenotypic plasticity in response to host and environment confounds species delimitation in Euphrasia. When grown in a common garden environment it is possible to identify some morphologically distinct taxa, though others represent morphologically similar shallow segregates. Trait differences present between some species and populations demonstrates the rapid evolution of distinct life history strategies in response to local ecological conditions.

Age-related reproductive performance of the Adélie Penguin, a long-lived seabird exhibiting similar outcomes regardless of individual life-history strategy

1. Age-related variation in reproductive performance in long-lived iteroparous vertebrate species is common, with performance being influenced by within-individual processes, such as improvement and senescence, in combination with among-individual processes, such as selective appearance and disappearance. Few studies of age-related reproductive performance have compared the role of these drivers within a metapopulation, subject to varying degrees of resource competition. 2. We accounted for within- and among-individuals changes among known-aged Adélie penguins (Pygoscelis adeliae) during 17 years (1997 to 2013), at three clustered colonies of disparate size, to understand patterns in age-related reproductive success during early and late adulthood. 3. Age at first reproduction (AFR) was lowest, and number of breeding attempts highest, at the largest colony. Regardless of AFR, success improved with early post-recruitment experience. For both oldest and youngest recruitment groups, peak performance occurred at the end of their reproductive lifespan indicating a possible cost of reproduction. Intermediate recruitment groups reached peak performance in their mid-reproductive lifespan and with intermediate breeding experience, before decreasing. Breeding success was lowest for the initial breeding attempt regardless of AFR, but we observed subsequent variation relative to recruitment age. Gaining experience by delaying recruitment positively influenced reproductive performance early in the reproductive lifespan, and was most evident for the youngest breeders. Oldest recruits had the highest initial and peak breeding success. Differences in AFR resulted in tradeoffs in reproductive lifespan or timing of senescence but not in the overall number of breeding attempts. 4. Patterns differed as a function of colony size, and thus competition for resources. Early life improvement in performance at the larger colonies was primarily due to within-individual factors and at the largest colony, AFR. Regardless of colony size late-life performance was positively related to the age at last reproduction, indicating selective disappearance of lower performing individuals. 5. These results highlight that different life-history strategies were equally successful, indicating that individuals can overcome potential tradeoffs associated with early- and late-life performance. These results have important implications for understanding the evolution of life-history strategies responsible for driving population change.

FIGURE 10 in Life histories of Paucispinigera Freeman, Paraborniella Freeman and Paratendipes Kieffer (Diptera: Chironomidae) with phylogenetic considerations

FIGURE 10. Paratendipes sinespina sp. n. Larva. A. Antenna (inset, apical segments); B. Mentum; C. Ventromental plate; D. Labrum-epipharynx; E. Mandible.

FIGURE 8 in Life histories of Paucispinigera Freeman, Paraborniella Freeman and Paratendipes Kieffer (Diptera: Chironomidae) with phylogenetic considerations

FIGURE 8. Paratendipes sinespina sp. n. male (except B). A. Wing; B. Thorax lateral (♀), C. Thorax lateral (♂); D. Foretibial apex; E. Inner spur and comb of hind tibia; F. Hypopygium, left side hypopygium, dorsal view; G. ventral view, right side (stylised); H–J. Superior volsella: H, dorsal, I. ventral, J. dorso-lateral view of apex; K. Median volsella.

FIGURE 6. Paraborniella tonnoiri Freeman, pupa. A in Life histories of Paucispinigera Freeman, Paraborniella Freeman and Paratendipes Kieffer (Diptera: Chironomidae) with phylogenetic considerations

FIGURE 6. Paraborniella tonnoiri Freeman, pupa. A. Cephalic area; B. Abdomen, tergites; C. Sternite IV; D. Posterior of VIII ('comb'). Larva: E. Anterior dorsal head; F. Antenna; G. Labrum; H. Mandible; I. Mentum and ventromental plates.

FIGURE 7. Paraborniella tonnoiri Freeman, larva. A in Life histories of Paucispinigera Freeman, Paraborniella Freeman and Paratendipes Kieffer (Diptera: Chironomidae) with phylogenetic considerations

FIGURE 7. Paraborniella tonnoiri Freeman, larva. A. Antenna (b. 'pouch' on segment 1, c. with flagellum); B. Labrum, epipharynx, mandible; C. Mentum and ventromental plate; D. Head, anterior body; E. Habitus.

FIGURE 3. Paucispinigera approximata Freeman, larva. A in Life histories of Paucispinigera Freeman, Paraborniella Freeman and Paratendipes Kieffer (Diptera: Chironomidae) with phylogenetic considerations

FIGURE 3. Paucispinigera approximata Freeman, larva. A. Habitus (ethanol-preserved); B. Anterior dorsal head; C. Antenna; D. Labrum-epipharynx; E. S setae, detail; F. Mandible; G. Mentum, ventromental plates, labrum-epipharynx; H. Dorsomentum, detail; I. Anterior body.