Early-life adversity predicts performance and fitness in a wild social carnivore

1. Studies on humans indicate that encountering multiple sources of adversity in childhood increases the risk of poor long-term health and premature death. Far less is known about cumulative effects of adversity during early life in wildlife. 2. Focusing on the spotted hyena Crocuta crocuta, a social mammal with small litters, extensive maternal care, slow development and access to resources determined by social rank, we determined the contribution of ecological, maternal, social and demographic factors during early life on performance and fitness, and tested whether the impact of early-life adversity is cumulative. 3. Using longitudinal data from 666 female hyenas in the Serengeti National Park, we determined the early growth rate, survival to adulthood, age at first reproduction (AFR), lifetime reproductive success (LRS) and longevity. We fitted multivariate models in which we tested the effects of environmental factors on these performance measures. We then constructed a cumulative adversity index and fitted models to test the effect of this index on each performance measure. Finally, the value of cumulative adversity models was tested by comparing them to multivariate and single-effect models in which the effect of each environmental factor was considered separately. 4. High maternal rank decreased the AFR of daughters. Singleton and dominant cubs had higher growth rate than subordinate cubs, and singletons also had a higher survival chance to adulthood than subordinates. Daughters of prime age mothers had a higher growth rate, longevity and LRS. Little and heavy rainfall decreased survival to adulthood. Increasing numbers of lactating female clan members decreased growth rate, survival to adulthood and LRS. Cumulative adversity negatively affected short-term performance and LRS. Multivariate models outperformed cumulative adversity and single-effect models for all measures except for AFR and longevity, for which single-effect models performed better. 5. Our results suggest that in some wildlife populations the combination of specific conditions in early life may matter more than the accumulation of adverse conditions as such

Does recolonization of wolves affect moose browsing damage on young Scots pine?

Ungulates frequently cause damage to human livelihoods, such as agriculture, livestock or forestry. In Sweden, forestry is the dominating land use and is a very important source of income. Moose (Alces alces) browsing commonly causes damage to young forest stands, mainly Scots pine (Punts sylvestris). Factors known to affect the level of moose browsing damage are moose density, forage availability, site productivity, tree species composition, snow depth, and infrastructure. One hypothesis is that the recent recolonization of wolves (Canis lupus) in Sweden may lead to a decrease in browsing damage levels, through an effect of wolf predation on moose density or moose behaviour. We used data from annual moose browsing damage surveys, long-term wolf monitoring, moose harvest statistics, habitat composition, snow depth, and road network to investigate the effect of wolf recolonization on moose browsing damage on Scots pine. Contrary to predicted, wolf territory establishment and duration showed an increase in the level of moose damage on young Scots pine. But, the effect size was small and it is questionable if it can be considered as biologically relevant. Overall, other factors were more important than wolves in explaining browsing damage on pine by moose. Presence and cover of deciduous species increased the occurrence of moose browsing damage on pine but reduced the level of damage. Decreasing snow depth and increasing road density both resulted in a lower level of damage. We suggest that the strong human impact on all trophic levels on the Swedish forest ecosystem through harvest and intense forestry practices is likely to override wolves' effects on density and behaviour of moose, as well as their potential effects on preferred browsing species for moose

Climate change does not decouple interactions between a central-place-foraging predator and its migratory prey

Little is known about potential cascading effects of climate change on the ability of predators to exploit mobile aggregations of prey with a spatiotemporal distribution largely determined by climatic conditions. If predators employ central-place foraging when rearing offspring, the ability of parents to locate sufficient prey could be reduced by climate change. In the Serengeti National Park, Tanzania, migratory species dominate mammalian herbivore biomass. These migratory herds exploit nutrient-rich vegetation on the southern plains in the rainy season and surface water in the northwest in the dry season. Female spotted hyenas Crocuta crocuta breed throughout the year and use long-distance central-place-foraging “commuting trips” to migratory herds to fuel lactation for ≥12 months. Changes in rainfall patterns that alter prey movements may decrease the ability of mothers to locate profitable foraging areas and thus increase their overall commuting effort, particularly for high-ranking females that have priority of access to food resources within their clan territory and thus less commuting experience. In hyena clan territories, this may be reflected by a decrease in migratory herd presence and a decrease in the presence of lactating females, as maternal den presence represents the opposite of commuting effort. We investigated the strength of the relationship between rainfall volume, migratory herd presence in three hyena clan territories, and the responses of lactating females to this climate/prey relationship in terms of maternal den presence, using an observation-based dataset spanning three decades. The probability of migratory herd presence in hyena clan territories increased with the amount of rainfall 2 months earlier, and maternal den presence increased with migratory herd presence. Rainfall volume substantially increased over 30 years, whereas the presence of migratory herds in hyena clans and the strength of the relationship between rainfall and migratory herd presence decreased. Hyenas thus adjusted well to the climate change-induced decreased the presence of migratory herds in their territories, since maternal den presence did not decrease over 30 years and still matched periods of high prey abundance, irrespective of female social status. These results suggest a high plasticity in the response of this keystone predator to environmental variability

Mécanismes moléculaires de la réponse des plantes aux radiations ionisantes. Exploration du rôle des glucosinolates dans la réponse antioxydante.

Terrestrial organisms are exposed to low doses of ionising radiation from natural or anthropogenic sources. The major effects of the radiations are due to DNA deterioration and water radiolysis which generates an oxidative stress by free radical production. Plants constitute good models to study the effects of ionising radiations and the search of antioxidant molecules because of their important secondary metabolism. Thus this thesis, funded by the Brittany region, characterized the physiological and molecular response of the model plant Arabidopsis thaliana to low (10 Gy) and moderate (40 Gy) doses of ionising radiation, and was therefore interested in glucosinolates, characteristic compounds of the Brassicaceae family. The global proteomic and transcriptomic studies carried out on this model revealed (1) a common response for both doses dealing with the activation of DNA repair mechanisms, cell cycle regulation and protection of cellular structures ; (2) an adjustment of the energetic metabolism and an activation of secondary compounds biosynthesis (i.e. glucosinolates and flavonoids) after the 10 Gy dose ; (3) an induction of enzymatic control of ROS, the regulation of cellular components recycling and of programmed cell death after the 40 Gy dose. The potential antioxidative role of glucosinolates was then explored. The in vitro antioxidative power of some glucosinolates and their derivative products were demonstrated. Their modulating effects against irradiation-induced damages were then tested in vivo by simple experimental approaches. The importance of the glucosinolate level to give a positive or negative effect was demonstrated.Les organismes terrestres sont exposés à des faibles doses de radiations ionisantes d'origine naturelle ou anthropique. Les effets majeurs de ces rayonnements sont dus aux dommages sur l'ADN et à la radiolyse de l'eau qui génère un stress oxydant via la production de radicaux libres. De part leur métabolisme secondaire développé, les végétaux sont utilisés pour l'étude des effets des radiations ionisantes et pour la recherche de molécules antioxydantes. Cette thèse financée par la région Bretagne a donc caractérisé la réponse physiologique et moléculaire de la plante modèle Arabidopsis thaliana à des doses faibles (10 Gy) à modérées (40 Gy) de radiations ionisantes, ainsi que le rôle des glucosinolates, composés caractéristiques de la famille des Brassicaceae. Deux études globales en protéomique et en transcriptomique ont révélée : (1) une réponse commune aux deux doses concernant les mécanismes de réparation de l'ADN, la régulation du cycle cellulaire et la protection des structures cellulaires ; (2) Un ajustement du métabolisme énergétique et une activation des voies métaboliques secondaires (i.e. glucosinolates et flavonoïdes) après la dose 10 Gy ; (3) une induction du contrôle enzymatique des ROS, du recyclage des composés cellulaires et de la mort cellulaire programmée après la dose 40 Gy. Le rôle protecteur des glucosinolates a ensuite été exploré. La capacité antioxydante in vitro de certains d'entre eux et de leurs dérivés a été montrée. Leurs effets modulateurs par rapport à l'irradiation ont été testés in vivo sur des marqueurs physiologiques de croissance. L'importance de la teneur en glucosinolates pour avoir un effet positif ou négatif a été mise en évidence

Frühe Lebensbedingungen und ihre langfristigen Folgen bei Tüpfelhyänen (Crocuta crocuta)

The conditions that individuals experience in early life, i.e. the period from conception to reproductive maturity, can have important consequences on their short and long-term performance and Darwinian fitness. In social mammals, the early-life environment can be defined in terms of ecological, maternal, social or demographic conditions. Little is known about the relative contribution of each type of environment on performance throughout life, whether multiple sources of adversity encountered early in life have a cumulative effect on performance measures, and whether particularly favourable conditions in early life may have a protective effect against the process of senescence, which corresponds to the decline in survival and reproductive probabilities with age. The purpose of this thesis was to provide a more comprehensive overview of how early-life environmental conditions can affect the behaviour (chapter 1), the short and long-term performance and fitness (chapter 2), and the senescence process (chapter 3) of spotted hyenas (Crocuta crocuta). This thesis used longitudinal data on individually known free-ranging spotted hyenas in three clans, obtained from a long-term research project in the Serengeti National Park, Tanzania. I focused specifically on females as they are philopatric and monitored from birth to death. In chapter 1, I found that the presence of migratory herds in spotted hyena clan territories increased with the amount of rainfall two months earlier, and that maternal den presence increased with the presence of migratory herds. I also found that despite the considerable increase in rainfall over the last 30 years, which has reduced the presence of migratory herds in spotted hyena clans, spotted hyenas have coped well with this climate change-induced effect, as maternal den presence has not decreased over the same period and still matched periods of high prey abundance in clan territories. The results of this first chapter thus show a high plasticity in the behavioural response of spotted hyenas to environmental variability and climate change. In chapter 2, I found that the ecological, maternal, social and demographic conditions experienced during early-life have different contributions on early growth rate, survival to adulthood, age at first reproduction (AFR), lifetime reproductive success (LRS) and longevity. I discovered, in particular, that daughters of prime-age mothers had higher growth rates, longevity and LRS than daughters of young or old mothers, that low or heavy rainfall decreased survival to adulthood and that a high number of lactating females in the clan in early life decreased growth rate, longevity and LRS. I show that cumulative adversity had a negative effect on short-term performance and LRS but that multivariate models outperformed cumulative adversity models. These results give a more complete picture of what constitutes favourable (silver-spoon) and adverse conditions for spotted hyena cubs in the Serengeti. In chapter 3, I focused on a key type of early life environment, as revealed by the results of my second chapter, maternal age at birth, to test whether daughters of prime-age mothers, who 14 benefited from a silver-spoon effect, also showed delayed senescence. Consistent with this idea, I found that silver-spooned daughters not only had higher probabilities of survival and reproduction at all ages and a longer reproductive lifespan, but also enjoyed a slower rate of reproductive senescence than daughters of young and old mothers. I also found that maternal age influenced the survival to adulthood of their grand-offspring. The results of this chapter have therefore revealed intergenerational effects of maternal age on fitness across three generations and indicate that prime-maternal age is associated with slower rates of actuarial and reproductive senescence, demonstrating that the silver-spoon effect can persist into late life. The results of my thesis provide new insights into how a wide range of factors during early life, including climatic factors such as rainfall, shape the life trajectories and performance of female spotted hyenas, including processes that occur in late life, as well as in the next generation.Die Bedingungen, die Individuen im frühen Leben, d.h. in der Zeit von der Empfängnis bis zur Geschlechtsreife, erfahren, können erhebliche Auswirkungen auf ihre kurz- und langfristigen Leistungen und ihre darwinistische Fitness haben. Bei sozialen Säugetieren kann das frühe Lebensumfeld durch ökologische, mütterliche, soziale oder demografische Bedingungen definiert werden. Es ist nur wenig darüber bekannt, welchen relativen Einfluss die einzelnen Umweltbedingungen auf die Leistung im Laufe des Lebens haben, ob mehrere Quellen von Widrigkeiten, die in der frühen Lebensphase auftreten, einen kumulativen Effekt auf die Leistung haben und ob besonders günstige Bedingungen in der frühen Lebensphase einen schützenden Effekt gegen den Prozess der Seneszenz haben können, der dem Rückgang der Überlebens- und Fortpflanzungswahrscheinlichkeit im Alter entspricht. Ziel dieser Arbeit war es, einen umfassenderen Überblick darüber zu geben, wie sich frühe Umweltbedingungen auf das Verhalten (Kapitel 1), die kurz- und langfristige Leistung und Fitness (Kapitel 2) und den Alterungsprozess (Kapitel 3) von Tüpfelhyänen (Crocuta crocuta) auswirken können. In dieser Arbeit wurden Longitudinaldaten über individuell bekannte freilebende Tüpfelhyänen in drei Clans verwendet, die im Rahmen eines Langzeitforschungsprojekts im Serengeti-Nationalpark in Tansania gewonnen wurden. Ich habe mich speziell auf die Weibchen konzentriert, da sie philopatrisch sind und von der Geburt bis zum Tod beobachtet werden. In Kapitel 1 stellte ich fest, dass die Anwesenheit wandernder Herden in den Gebieten von Tüpfelhyänen-Clans mit der Niederschlagsmenge zwei Monate zuvor zunahm und dass die Anwesenheit mütterlicher Höhlen mit der Anwesenheit wandernder Herden zunahm. Außerdem habe ich festgestellt, dass Tüpfelhyänen trotz der beträchtlichen Zunahme der Niederschläge in den letzten 30 Jahren, die die Anwesenheit wandernder Herden in Tüpfelhyänenclans verringert hat, gut mit dieser durch den Klimawandel bedingten Veränderung zurechtgekommen sind, da die Anwesenheit von Muttertieren in den Höhlen im gleichen Zeitraum nicht abgenommen hat und immer noch mit Zeiten hohen Beuteaufkommens in den Clanterritorien übereinstimmt. Die Ergebnisse dieses ersten Kapitels zeigen also eine hohe Plastizität in der Verhaltensreaktion von Tüpfelhyänen auf Umweltvariabilität und Klimawandel. In Kapitel 2 habe ich herausgefunden, dass die ökologischen, mütterlichen, sozialen und demografischen Bedingungen, die in der frühen Lebensphase herrschen, unterschiedliche Auswirkungen auf die frühe Wachstumsrate, das Überleben bis zum Erwachsenenalter, das Alter bei der ersten Reproduktion (AFR), den lebenslangen Reproduktionserfolg (LRS) und die Langlebigkeit haben. Ich entdeckte insbesondere, dass Töchter von Müttern im besten Alter höhere Wachstumsraten, Langlebigkeit und LRS aufwiesen als Töchter von jungen oder alten Müttern, dass geringe oder starke Regenfälle die Überlebensrate bis 16 zum Erwachsenenalter verringerten und dass eine hohe Anzahl säugender Weibchen im Clan in der frühen Lebensphase die Wachstumsrate, Langlebigkeit und LRS verringerte. Ich zeige, dass kumulative Widrigkeiten eine negative Auswirkung auf die kurzfristige Leistung und die LRS hatten, dass aber multivariate Modelle die kumulativen Widrigkeitsmodelle übertrafen. Diese Ergebnisse vermitteln ein vollständigeres Bild davon, was günstige (Silberlöffel) und ungünstige Bedingungen für Tüpfelhyänenjunge in der Serengeti ausmacht. In Kapitel 3 konzentrierte ich mich auf einen Schlüsseltyp des frühen Lebensumfelds, der sich aus den Ergebnissen meines zweiten Kapitels ergab: Das Alter der Mutter bei der Geburt. Dabei wurde untersucht, ob Töchter von Müttern im besten Alter, die von einem Silberlöffel-Effekt profitierten, auch eine verzögerte Seneszenz aufwiesen. In Übereinstimmung mit dieser Idee fand ich heraus, dass Töchter, die von einem Silberlöffel-Effekt profitierten, nicht nur eine höhere Überlebens- und Reproduktionswahrscheinlichkeit in jedem Alter und eine längere reproduktive Lebensdauer hatten, sondern auch eine langsamere reproduktive Seneszenz als Töchter von jungen und alten Müttern. Ich konnte feststellen, dass das Alter der Mutter das Überleben bis zum Erwachsenenalter ihrer Enkelkinder beeinflusst. Die Ergebnisse dieses Kapitels haben daher intergenerationalen Auswirkungen des mütterlichen Alters auf die Fitness über drei Generationen hinweg aufgezeigt und zeigen, dass das mütterliche Höchstalter mit einem längeren Überleben und langsamerer reproduktiver Seneszenz verbunden ist, was zeigt, dass der Silberlöffel-Effekt bis ins späte Leben andauern kann. Die Ergebnisse meiner Dissertation liefern neue Erkenntnisse darüber, wie eine breite Palette von Faktoren während des frühen Lebens, einschließlich klimatischer Faktoren wie Niederschlag, den Lebensverlauf und die Leistung weiblicher Tüpfelhyänen prägen, einschließlich der Prozesse, die im späten Leben und in der nächsten Generation auftreten

Mécanismes moléculaires de la réponse des plantes aux radiations ionisantes. Exploration du rôle des glucosinolates dans la réponse antioxydante.

Terrestrial organisms are exposed to low doses of ionising radiation from natural or anthropogenic sources. The major effects of the radiations are due to DNA deterioration and water radiolysis which generates an oxidative stress by free radical production. Plants constitute good models to study the effects of ionising radiations and the search of antioxidant molecules because of their important secondary metabolism. Thus this thesis, funded by the Brittany region, characterized the physiological and molecular response of the model plant Arabidopsis thaliana to low (10 Gy) and moderate (40 Gy) doses of ionising radiation, and was therefore interested in glucosinolates, characteristic compounds of the Brassicaceae family. The global proteomic and transcriptomic studies carried out on this model revealed (1) a common response for both doses dealing with the activation of DNA repair mechanisms, cell cycle regulation and protection of cellular structures ; (2) an adjustment of the energetic metabolism and an activation of secondary compounds biosynthesis (i.e. glucosinolates and flavonoids) after the 10 Gy dose ; (3) an induction of enzymatic control of ROS, the regulation of cellular components recycling and of programmed cell death after the 40 Gy dose. The potential antioxidative role of glucosinolates was then explored. The in vitro antioxidative power of some glucosinolates and their derivative products were demonstrated. Their modulating effects against irradiation-induced damages were then tested in vivo by simple experimental approaches. The importance of the glucosinolate level to give a positive or negative effect was demonstrated.Les organismes terrestres sont exposés à des faibles doses de radiations ionisantes d'origine naturelle ou anthropique. Les effets majeurs de ces rayonnements sont dus aux dommages sur l'ADN et à la radiolyse de l'eau qui génère un stress oxydant via la production de radicaux libres. De part leur métabolisme secondaire développé, les végétaux sont utilisés pour l'étude des effets des radiations ionisantes et pour la recherche de molécules antioxydantes. Cette thèse financée par la région Bretagne a donc caractérisé la réponse physiologique et moléculaire de la plante modèle Arabidopsis thaliana à des doses faibles (10 Gy) à modérées (40 Gy) de radiations ionisantes, ainsi que le rôle des glucosinolates, composés caractéristiques de la famille des Brassicaceae. Deux études globales en protéomique et en transcriptomique ont révélée : (1) une réponse commune aux deux doses concernant les mécanismes de réparation de l'ADN, la régulation du cycle cellulaire et la protection des structures cellulaires ; (2) Un ajustement du métabolisme énergétique et une activation des voies métaboliques secondaires (i.e. glucosinolates et flavonoïdes) après la dose 10 Gy ; (3) une induction du contrôle enzymatique des ROS, du recyclage des composés cellulaires et de la mort cellulaire programmée après la dose 40 Gy. Le rôle protecteur des glucosinolates a ensuite été exploré. La capacité antioxydante in vitro de certains d'entre eux et de leurs dérivés a été montrée. Leurs effets modulateurs par rapport à l'irradiation ont été testés in vivo sur des marqueurs physiologiques de croissance. L'importance de la teneur en glucosinolates pour avoir un effet positif ou négatif a été mise en évidence

Détection du stress oxydant induit par des faibles doses d'irradiations ionisantes sur modèle végétal. Marqueurs d'exposition et modulation de la radiosensibilité par les glucosinolates.

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Age at first reproduction in wolves: different patterns of density dependence for females and males

Age at first reproduction constitutes a key life-history trait in animals and is evolutionarily shaped by fitness benefits and costs of delayed versus early reproduction. The understanding of how intrinsic and extrinsic changes affects age at first reproduction is crucial for conservation and management of threatened species because of its demographic effects on population growth and generation time. For a period of 40 years in the Scandinavian wolf (Canis lupus) population, including the recolonization phase, we estimated age at first successful reproduction (pup survival to at least three weeks of age) and examined how the variation among individuals was explained by sex, population size (from 1 to 74 packs), primiparous or multiparous origin, reproductive experience of the partner and inbreeding. Median age at first reproduction was 3 years for females (n = 60) and 2 years for males (n = 74), and ranged between 1 and 8-10 years of age (n = 297). Female age at first reproduction decreased with increasing population size, and increased with higher levels of inbreeding. The probability for males to reproduce later first decreased, reaching its minimum when the number of territories approached 40-60, and then increased with increasing population size. Inbreeding for males and reproductive experience of parents and partners for both sexes had overall weak effects on age at first reproduction. These results allow for more accurate parameter estimates when modelling population dynamics for management and conservation of small and vulnerable wolf populations, and show how humans through legal harvest and illegal hunting influence an important life-history trait like age at first reproduction

Mécanismes moléculaires de la réponse d Arabidopsis thaliana aux radiations ionisantes (exploration du rôle des glucosinolates dans la réponse antioxydante)

Les organismes terrestres sont exposés à des faibles doses de radiations ionisantes d origine naturelle ou anthropique. Les effets majeurs de ces rayonnements sont dus aux dommages sur l ADN et à la radiolyse de l eau qui génère un stress oxydant via la production de radicaux libres. De part leur métabolisme secondaire développé, les végétaux sont utilisés pour l étude des effets des radiations ionisantes et pour la recherche de molécules antioxydantes. Cette thèse financée par la région Bretagne a donc caractérisé la réponse physiologique et moléculaire de la plante modèle Arabidopsis thaliana à des doses faibles (10 Gy) à modérées (40 Gy) de radiations ionisantes, ainsi que le rôle des glucosinolates, composés caractéristiques de la famille des Brassicaceae. Deux études globales en protéomique et en transcriptomique ont révélée: (1) une réponse commune aux deux doses concernant les mécanismes de réparation de l ADN, la régulation du cycle cellulaire et la protection des structures cellulaires; (2) Un ajustement du métabolisme énergétique et une activation des voies métaboliques secondaires (i.e. glucosinolates et flavonoïdes) après la dose 10 Gy ; (3) une induction du contrôle enzymatique des ROS, du recyclage des composés cellulaires et de la mort cellulaire programmée après la dose 40 Gy. Le rôle protecteur des glucosinolates a ensuite été exploré. La capacité antioxydante in vitro de certains d entre eux et de leurs dérivés a été montrée. Leurs effets modulateurs par rapport à l irradiation ont été testés in vivo sur des marqueurs physiologiques de croissance. L importance de la teneur en glucosinolates pour avoir un effet positif ou négatif a été mise en évidence.Terrestrial organisms are exposed to low doses of ionising radiation from natural or anthropogenic sources. The major effects of the radiations are due to DNA deterioration and water radiolysis which generates an oxidative stress by free radical production. Plants constitute good models to study the effects of ionising radiations and the search of antioxidant molecules because of their important secondary metabolism. Thus this thesis, funded by the Brittany region, characterized the physiological and molecular response of the model plant Arabidopsis thaliana to low (10 Gy) and moderate (40 Gy) doses of ionising radiation, and was therefore interested in glucosinolates, characteristic compounds of the Brassicaceae family. The global proteomic and transcriptomic studies carried out on this model revealed (1) a common response for both doses dealing with the activation of DNA repair mechanisms, cell cycle regulation and protection of cellular structures ; (2) an adjustment of the energetic metabolism and an activation of secondary compounds biosynthesis (i.e. glucosinolates and flavonoids) after the 10 Gy dose ; (3) an induction of enzymatic control of ROS, the regulation of cellular components recycling and of programmed cell death after the 40 Gy dose. The potential antioxidative role of glucosinolates was then explored. The in vitro antioxidative power of some glucosinolates and their derivative products were demonstrated. Their modulating effects against irradiation-induced damages were then tested in vivo by simple experimental approaches. The importance of the glucosinolate level to give a positive or negative effect was demonstrated.RENNES1-BU Sciences Philo (352382102) / SudocSudocFranceF

Modulation par les glucosinolates de la réponse aux faibles doses de radiations ionisantes chez Arabidopsis thaliana.

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