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opencc-zeroNov 2022View details →

Experimental reduction of haemosporidian infection affects maternal reproductive investment, parental behaviour, and offspring condition

When hosts have a long coevolutionary history with their parasites, fitness costs of chronic infection have often been assumed to be negligible. Yet, experimental manipulation of infections sometimes reveals effects of parasites on their hosts, particularly during reproduction. Whether these effects translate into fitness costs remains unclear. Here, we present the results of an experimental study conducted in a free-ranging population of red-winged blackbirds (Agelaius phoeniceus) naturally experiencing a high prevalence of haemosporidian infections, with > 95% of breeding adults infected with parasites from one or more haemosporidian genus. To assess effects of infection during reproduction, we manipulated adult red-winged blackbird females' parasite burden by administering an anti-haemosporidian medication before onset of egg-laying. Experimental reduction of infection resulted in significant benefits to mothers and their offspring. Medicated females laid heavier clutches, invested more in incubation and provisioning behaviour, and produced more fledglings than control females. Nestlings of medicated females had higher haematocrit, higher blood glucose, and lower reactive oxygen metabolites than nestlings of control females. Overall, our results provide evidence that, even in a species with a long history of high prevalence of infection, parasites can lead to decreased maternal investment and offspring quality, substantially reducing fitness.

publicNov 2022View details →

Experimental reduction of haemosporidian infection affects maternal reproductive investment, parental behaviour, and offspring condition

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publicMar 2021View details →

Split sex ratio due to maternal condition

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publicOct 2024View details →

Data from: Productive foraging grounds enhance maternal condition and offspring quality in a capital breeding species

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Data from: Transgenerational effects in an ecological context: conditioning of adult sea urchins to upwelling conditions alters maternal provisioning and progeny phenotype

Transgenerational plasticity occurs when the conditions experienced by the parental generation influences the phenotype of their progeny. This may in turn affect progeny performance and physiological tolerance, providing a means by which organisms cope with rapid environmental change. We conditioned adult purple sea urchins, Strongylocentrotus purpuratus, to combined pCO⁠2 and temperature conditions reflective of in situ conditions of their natural habitat, the benthos in kelp forests of nearshore California, and then assessed the performance of their progeny raised under different pCO⁠2 levels. Adults were conditioned during gametogenesis to treatments that reflected static non-upwelling (~650 μatm pCO⁠2, ~17°C) and upwelling (~1300 μatm pCO⁠2, ~13°C) conditions. Following approximately 4 months of conditioning, the adults were spawned and embryos were raised under low pCO⁠2 (~450 μatm pCO⁠2) or high pCO⁠2 (~1050 μatm pCO⁠2) treatments to determine if differential maternal conditioning impacted the progeny response to a single abiotic stressor: pCO⁠2. We examined the size, protein content, and lipid content of eggs from both sets of conditioned female urchins. Offspring were sampled at four stages of early development: hatched blastula, gastrula, prism, and echinopluteus. This resulted in four sets of offspring: (1) progeny from non-upwelling-conditioned mothers raised under low pCO⁠2, (2) progeny from non-upwelling-conditioned mothers raised under high pCO⁠2, (3) progeny from upwelling-conditioned mothers raised under low pCO⁠2, and (4) progeny from upwelling-conditioned mothers raised under high pCO⁠2. We then assessed the effects of maternal conditioning along with the effects of developmental pCO⁠2 levels on body size of the progeny. Our results showed that differential maternal conditioning had no impact on average egg size, although non-upwelling females produced eggs that were more variable in size. Maternal conditioning did not affect protein content but did have a modest impact on egg lipid content. Developing embryos whose mothers were conditioned to simulated upwelling conditions (~1300 μatm pCO⁠2, ~13°C) were greater in body size, although this effect was no longer evident at the echinopluteus larval stage. Although maternal conditioning affected offspring body size, the pCO⁠2 levels under which the embryos were raised did not. Overall, this laboratory study provides insight into how transgenerational effects may function in nature. The impacts of parental environmental history on progeny phenotype during early development have important implications regarding recruitment success and population-level effects.

opencc-zeroApr 2024View details →

Maternal investment and early thermal conditions affect performance and antipredator responses

Exposure to increased temperatures during early development can lead to phenotypic plasticity in morphology, physiology, and behaviour across a range of ectothermic animals. In addition, maternal effects are known to be important contributors to phenotypic variation in offspring. Whether the two factors interact to shape offspring morphology and behaviour has been barely explored. This is critical since climate change is expected to impact both incubation temperature and maternal resource allocation and stress levels. Using a fully factorial design, and Bayesian multivariate mixed models, we explored how the manipulation of early thermal environment and yolk-quantity in eggs affected the morphology, performance and antipredator behaviour of two sympatric Australian skink species (Lampropholis delicata and L. guichenoti). We found that juveniles from the hot treatment were larger than those on the cold treatment in L. guichenoti but not L. delicata. Using repeated behavioural measures for individual lizards, we found an interaction between incubation temperature and maternal investment in performance, with running speed being affected in a species-specific way by the treatment. We predicted that changes in performance should influence antipredator responses. In support of this prediction, we found that maternal investment impacted antipredator behaviour, with animals from the yolk-reduced and cold treatment resuming activity faster after a simulated predatory attack in L. delicata. However, the prediction was not supported in L. guichenoti. Our results highlight the importance of exploring the multifaceted role that environments play across generations to understand how different anthropogenic factors will impact wildlife in the future.

publicMay 2019View details →

Data from: Transgenerational effects in an ecological context: conditioning of adult sea urchins to upwelling conditions alters maternal provisioning and progeny phenotype

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publicApr 2024View details →

Maternal investment and early thermal conditions affect performance and antipredator responses

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Data from: Maternal effects obscure condition-dependent sex allocation in changing environments

Climate change increases environmental fluctuations which thereby impact population demography. Species with temperature-dependent sex determination may experience more extreme sex ratio skews, but this has not been considered in species with chromosomally-determined sex. However, anticipatory maternal effects cause lifelong physiological changes impacting sex ratios. Here we show, in mice, that more sons were born to mothers in good condition when their breeding environment matched their gestational environment, consistent with theoretical predictions, but mothers in mismatched environments have no condition sex-ratio relationship. Thus, the predicted effect of condition on sex ratio was obscured by maternal effects when the environment changed. This may explain extreme or unexpected sex ratio skews in reintroduced or translocated populations, and sex ratio skews may become more common and less predictable with accelerating environmental change.

opencc-zeroDec 2015View details →

Data from: Altered natal dispersal at the range periphery: the role of behavior, resources, and maternal condition

Natal dispersal outcomes are an interplay between environmental conditions and individual phenotypes. Peripheral, isolated populations may experience altered environmental conditions and natal dispersal patterns that differ from populations in contiguous landscapes. We document nonphilopatric, sex-biased natal dispersal in an endangered small mammal, the Mt. Graham red squirrel (Tamiasciurus hudsonicus grahamensis), restricted to a single mountain. Other North American red squirrel populations are shown to have sex-unbiased, philopatric natal dispersal. We ask what environmental and intrinsic factors may be driving this atypical natal dispersal pattern. We test for the influence of proximate factors and ultimate drivers of natal dispersal: habitat fragmentation, local population density, individual behavior traits, inbreeding avoidance, competition for mates, and competition for resources, allowing us to better understand altered natal dispersal patterns at the periphery of a species' range. A juvenile squirrel's body condition and its mother's mass in spring (a reflection of her intrinsic quality and territory quality) contribute to individual behavioral tendencies for movement and exploration. Resources, behavior, and body condition have the strongest influence on natal dispersal distance, but affect males and females differently. Male natal dispersal distance is positively influenced by its mother's spring body mass and individual tendency for movement; female natal dispersal distance is negatively influenced by its mother's spring body mass and positively influenced by individual tendency for movement. An apparent feedback between environmental variables and subsequent juvenile behavioral state contributes to an altered natal dispersal pattern in a peripheral population, highlighting the importance of studying ecological processes at the both range center and periphery of species' distributions.

Data from: Benefits of extra food to reproduction depend on maternal condition

The amount of food resources available to upper-level consumers can show marked variations in time and space, potentially resulting in food limitation. The availability of food resources during reproduction is a key factor modulating variation in reproductive success and life-history trade-offs, including patterns of resource allocation to reproduction vs. self-maintenance, ultimately impacting on population dynamics. Food provisioning experiments constitute a popular approach to assess the importance of food limitation for vertebrate reproduction. In this study of a mesopredatory avian species, the lesser kestrel (Falco naumanni), we provided extra food to breeding individuals from egg laying to early nestling rearing. Extra food did not significantly affect adult body condition or oxidative status. However, it increased the allocation of resources to flight feathers moult and induced females to lay heavier eggs. Concomitantly, it alleviated the costs of laying heavier eggs for females in poor body condition, and reduced their chances of nest desertion (implying complete reproductive failure). Extra food provisioning improved early nestling growth (body mass and feather development). Moreover, extra food significantly reduced the negative effects of ectoparasites on nestling body mass, while fostering forearm (a flight apparatus trait) growth among highly parasitized nestlings. Our results indicate that lesser kestrels invested the extra food mainly to improve current reproduction, suggesting that population growth in this species can be limited by food availability during the breeding season. In addition, extra food provisioning reduced the costs of the moult-breeding overlap and affected early growth trade-offs by mitigating detrimental ectoparasite effects on growth and enhancing development of the flight apparatus with high levels of parasitism. Importantly, our findings suggest that maternal condition is a major trait modulating the benefits of extra food to reproduction, whereby such benefits mostly accrue to low-quality females with poor body condition.

Data from: Variation in offspring development is driven more by weather and maternal condition than predation risk

1. Variation in offspring development is expected to be driven by constraints on resource allocation between growth and maintenance (e.g., thermoregulation). Rapid post-natal development decreases predation risk, while inclement weather likely prolongs development. For taxa with parental care, parental behaviour may buffer offspring against some extrinsic drivers. 2. Using a 7-year dataset from an alpine population of horned lark Eremophila alpestris, a ground-nesting songbird in northern British Columbia, Canada, we investigated multiple potential drivers of variation in incubation and nestling development duration. 3. Using path analysis, we evaluated the direct effects of weather, predation risk, and parental care on offspring development, as well as, indirect developmental 'carry-over' effects of conditions during incubation on the nestling period. 4. Nestling period duration varied by nearly 100% (7–13 days) and incubation duration by 40% (10–14 days). Cold ambient temperatures late in the nestling period prolonged development by 1 day for every 2 days below 10°C; particularly when combined with heavy precipitation. Rapid nestling development was associated with high predation risk, and prolonging development incurred a nest survival cost (–2.3%/day). Females in good condition created nest environments that promoted rapid nestling development periods (average = 8–9 days) compared to poor condition females during harsh, early-season conditions (10–11 days), indicating buffering capabilities against environmental constraints. Incubation duration was only weakly correlated with fledging age (r = –0.21) suggesting minimal developmental carry-over effects. 5. Given high nest predation risk, immediate fitness benefits can be derived by overcoming environmental constraints and reducing development time. While predation risk was influential, inclement weather and maternal condition had stronger effects on within-population variation in development time. We highlight the importance of addressing multiple drivers of variation in key life-history traits and provide context for understanding life-history theory under changing environmental conditions.

FIG. 2 in Maternal Body Size and Condition Predict Measures of Reproductive Success and Future Reproductive Allocation in Territorial Eastern Red-Backed Salamanders

FIG. 2. The regression of number of surviving offspring (at 185 d posthatching) on (A) maternal body size (SVL in mm) and (B) maternal condition (residuals of the regression of maternal mass, mm, on maternal body size, SVL in mm).

FIG. 3 in Maternal Body Size and Condition Predict Measures of Reproductive Success and Future Reproductive Allocation in Territorial Eastern Red-Backed Salamanders

FIG. 3. The body size of siblings that did and did not survive to 185 d after hatching. Each point represents the mean SVL of siblings from a single female that did or did not survive. The diagonal line represents the hypothetical situation in which the body size of siblings that did and did not survive are equal.

FIG. 1 in Maternal Body Size and Condition Predict Measures of Reproductive Success and Future Reproductive Allocation in Territorial Eastern Red-Backed Salamanders

FIG. 1. The regression of (A) clutch size (number of eggs) and of (B) mean juvenile size (measured as mean snout–vent length, SVL, in mm per clutch) on maternal body size (SVL in mm).

FIG. 4 in Maternal Body Size and Condition Predict Measures of Reproductive Success and Future Reproductive Allocation in Territorial Eastern Red-Backed Salamanders

FIG. 4. The regression of number of developing oocytes (visible through the body wall) produced by females on (A) maternal body size (SVL in mm) and (B) maternal condition (residuals of the regression of maternal mass, mm, on maternal body size, SVL in mm).

publicMar 2019View details →

Data from: Maternal effects obscure condition-dependent sex allocation in changing environments

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publicJan 2020View details →

Data from: Benefits of extra food to reproduction depend on maternal condition

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