Energetikk i sesongmessige miljøer: reinsdyr som fokusart

How endothermic animals manage and allocate energy to critical processes (maintenance, reproduction, thermoregulation and activity) can determine their success and survival. The balance in energy expenditure related to these processes can also influence their ability to respond to disturbances in their environment. In seasonal environments, the predictable annual changes in resources (food, nutrients and water) have led to a large range of adaptations in animals, including seasonal adjustments in energy expenditure, body temperature and activity levels. The aim of my thesis is to evaluate the relative importance of central drivers of energy expenditure under different seasonal and reproductive contexts in reindeer. Reindeer provide an excellent example of a highly adapted species to the seasonal changes in food availability, temperature and light conditions of the Arctic and sub-Arctic regions. Studying the interplay between energy expenditure, environmental variation and physiological states in this species can shed light on how non-hibernating animals balance energy expenditure in seasonal environments. My thesis consists of three papers. The data collected comes from two different reindeer populations, in Svalbard (Svalbard reindeer, Papers I and II) and in Northern Finland (domestic reindeer, Paper III). In both systems I use two common methods for measuring energetics in free-living animals, the doubly labelled water (DLW) method to quantify daily energy expenditure (DEE) over a given time period (1-2 weeks), and the heart rate method, in which heart rate serves as an indicator of energy expenditure over longer time periods (>1 month). In all three papers, I use biologgers to monitor behaviour (activity levels) and physiology (subcutaneous body temperature; Tsc) in relation to DEE (Papers I and III) or heart rate (Papers II and III). The role of body mass for winter energetics and fasting endurance (how long animals can survive on their internal body reserves) is the main focus of Paper I. In Paper II, I explored determinants of heart rate to identify constraints on energy management strategies within summer and winter. Finally, in Paper III, I investigate drivers of energy expenditure during peak lactation in domestic reindeer and their physiological and behavioural responses to extreme warm weather. In winter, the most important determinant for energy expenditure was fat-free body mass (likely reflecting maintenance requirements), and to a lesser extent Tsc and activity levels (Paper I). Lactating females have overall higher energy demands (respiration + energy exported through milk), but lactation was not a driver of seasonal variation in energy expenditure, as there were only small differences in energy expenditure (respiration) between lactating and non-lactating females within summer (Papers II and III). Adaptations to seasonality in their environment has resulted in summer and winter phenotypes, in which there is likely less room for additional variation in energy expenditure (Paper II). Yet this variation appears to be greater in summer, when food is abundant (Papers II and III), than in winter, when food is scarce. Monitoring animal behaviour and physiology with the use of biologgers allow us to study energetics in free-living animals, and models of mammalian energetics can be important tools for predicting responses to climate change. For instance, I show that reindeer do not elevate heart rates in response to hot environmental conditions, which suggests that other mechanisms are involved to alleviate heat stress (Paper III). I also show that both activity and Tsc are important components of energy expenditure, but adjustments in either of these are not as important as the size of autumn fat stores (Paper I), which can influence survival in warm and icy winters. The findings from my thesis demonstrate that the relative contribution of body mass and body composition, temperature (ambient and body), reproduction and activity as drivers of energy expenditure depended on seasonal, individual and reproductive contexts. Future research should therefore consider how individual variation, thermoregulation and body mass can be incorporated into models to predict long-term fitness consequences of different strategies for energy management.Endoterme (varmblodige) dyrs overlevelsesevne påvirkes i stor grad av hvordan dyra tilpasser sitt energiforbruk i forhold til viktige prosesser som overlevelse, reproduksjon, regulering av kroppstemperatur og aktivitetsnivå. Balansen i energiforbruk mellom disse prosessene vil også påvirke dyras evne til å respondere på forstyrrelser i miljøet. Mange arter har utviklet tilpasninger til forutsigbare sesongmessige endringene i tilgang på ressurser som mat, næringsstoffer og vann. Slike tilpasninger kan være endringer i energiforbruk, kroppstemperatur og aktivitetsnivå. Målet for denne avhandlingen er å vurdere det relative bidraget av prosessene som påvirker energiforbruk hos reinsdyr i forskjellige sesonger og under forskjellige stadier av reproduksjon. Reinsdyr er et ypperlig eksempel på en art som er godt tilpasset sesongvariasjonene i mattilgang, temperatur og lysforhold i Arktis og sub-arktiske strøk. Å studere samspillet mellom energiforbruk og endringer i både miljøet og fysiologiske tilstander kan hjelpe oss med å forstå hvordan dyr kan balansere energiforbruket sitt i sesongmessige miljø. Denne avhandlingen består av tre artikler. Innsamlet data kommer fra to forskjellige studiesystemer, på Svalbard (Svalbardrein, artikkel I og II) og i Nord-Finland (tamrein, artikkel III). I begge systemene bruker jeg to vanlige metoder for å måle energetikk i frittlevende dyr. Dette er dobbeltmerket vannmetoden for å måle daglig energiforbruk over en gitt tidsperiode (1-2 uker), og hjertefrekvensmetoden, der dyrets puls fungerer som en indikator på energiforbruk over lengre tidsperioder (> 1 måned). I alle artiklene bruker jeg biologgere til å overvåke atferd (aktivitetsnivå) og fysiologi (subkutan kroppstemperatur; Tsc) i forhold til daglig energiforbruk (artikler I og III) eller hjertefrekvens (artikler II og III). Fokuset i artikkel I er hvordan kroppsvekt og kroppssammensetning (fett og fettfri masse) påvirker energiforbruket om vinteren, og hvor lenge reinsdyr kan overleve på sine indre kroppsreserver. I artikkel II utforsker jeg hva som påvirker hjertefrekvens for å identifisere strategier og begrensninger av energiforbruk og -balanse sommer og vinter. I artikkel III undersøker jeg hva som påvirker energiforbruket hos lakterende tamrein når melkeproduksjonen er høyest, videre også dyras fysiologiske og atferdsmessige reaksjoner på ekstremt høye temperaturer (varmebølge). Om vinteren var det dyras fettfrie kroppsmasse som hadde størst påvirkning på energiforbruket, som sannsynligvis gjenspeiler vedlikeholdskrav, etterfulgt av Tsc og aktivitetsnivå (artikkel I). Simler som diet hadde høyere energibehov (respirasjon + energi eksportert i melka), men laktasjon i seg selv var ikke pådriveren for sesongmessige variasjoner i energiforbruk (respirasjon), da det bare var små forskjeller mellom simler med kalv (diende) og uten kalv om sommeren (artikler II og III). Overvåking av dyrs atferd og fysiologi ved bruk av biologgere tillater oss å studere energetikk hos frittlevende dyr. Modellering av energetikk kan være viktige verktøy for å forutsi pattedyrs responser til klimaendringer. Jeg viser for eksempel at reinsdyr ikke øker hjertefrekvensen når det er varmt om sommeren, noe som antyder at andre fysiologiske mekanismer er involvert for å lindre dyras varmestress (artikkel III). Økende temperaturer i Arktis er en utfordring som vil bli større med klimaendringene. Jeg viser også at både aktivitet og Tsc er viktige komponenter i reinsdyrs energiforbruk. Dyras nedjustering av disse er derimot ikke like viktig som størrelsen på deres indre fettlagre (artikkel I), for å overleve milde og isete vintre. Resultatene fra min forskning viser at det relative bidraget av kroppsvekt og kroppssammensetning, temperatur (omgivelses- og kropps-), reproduksjon og aktivitet som påvirkere av energiforbruk avhenger av sesongmessige, individuelle og reproduktive sammenhenger. Fremtidig forskning bør derfor vurdere hvordan individuell variasjon, termoregulering og kroppsvekt kan innarbeides i modeller for å forutsi langsiktige konsekvenser av variasjoner i energiforbruk

Fat storage influences fasting endurance more than body size in an ungulate

The fasting endurance hypothesis (FEH) predicts strong selection for large body size in mammals living in environments where food supply is interrupted over prolonged periods of time. The Arctic is a highly seasonal and food restricted environment, but contrary to predictions from the FEH, empirical evidence shows that Arctic mammals are often smaller than their temperate conspecifics. Intraspecific studies integrating physiology and behaviour of different‐sized individuals, may shed light on this paradox. We tested the FEH in free‐living Svalbard reindeer (Rangifer tarandus platyrhynchus). We measured daily energy expenditure (DEE), subcutaneous body temperature (Tsc) and activity levels during the late winter in 14 adult females with body masses ranging from 46.3 to 57.8 kg. Winter energy expenditure (WEE) and fasting endurance (FE) were modelled dynamically by combining these data with body composition measurements of culled individuals at the onset of winter (14 years, n = 140) and variation in activity level throughout winter (10 years, n = 70). Mean DEE was 6.3±0.7 MJ day−1. Lean mass, Tsc and activity had significantly positive effects on DEE. Across all 140 individuals, mean FE was 85±17 days (range 48–137 days). In contrast to the predictions of the FEH, the dominant factor affecting FE was initial fat mass, while body mass and FE were not correlated. Furthermore, lean mass and fat mass were not correlated. FE was on average 80% (45 days) longer in fat than lean individuals of the same size. Reducing activity levels by ~16% or Tsc by ~5% increased FE by 7%, and 4%, respectively. Our results fail to support the FEH. Rather, we demonstrate that (i) the size of fat reserves can be independent of lean mass and body size within a species, (ii) ecological and environmental variation influence FE via their effects on body composition, and (iii) physiological and behavioural adjustments can improve FE within individuals. Altogether, our results suggest that there is a selection in Svalbard reindeer to accumulate body fat, rather than to grow structurally large. he Arctic, activity, biologging, daily energy expenditure, doubly labelled water, intraspecific scaling, subcutaneous body temperature, Svalbard reindeer to accumulate body fat, rather than to grow structurally large. </ol

The oxidative debt of fasting : evidence for short to medium-term costs of advanced fasting in adult king penguins

This research was funded by the French Polar Institute (IPEV–Research Program 119) and the French National Centre for Scientific Research (CNRS-INEE). We are especially grateful to Dominic L. Cram and one anonymous reviewer for helpful comments on the paper. Field logistic support was provided by Terres Australes et Antarctiques Françaises. QS was funded by a doctoral fellowship from the Ministère Français de l’Education Supérieur et de la Recherche.Peer reviewedPublisher PD

Geographic patterns of skull variation in two species of cavies of the genus microcavia (Rodentia, caviidae)

We study the geographical variation of the skull in the cavies Microcavia australis and M. maenas and its association with environmental variables. We tested four hypotheses previously proposed to explain the geographic patterns of morphological variation i) heat conservation; ii) heat dissipation; iii) primary productivity and iv) seasonality. We used 16 cranial measurements taken from 180 individuals. We analyzed the spatial variation in cranial morphology through Generalized Additive Models. Both species showed a north-south clinal gradient in skull size (increasing towards colder, less seasonal environments, with lower summer rainfalls in M. australis and towards warmer and seasonal environments in M. maenas). Microcavia australis presented greater ecomorphological variability than M. maenas, in agreement with its wider distribution and occurrence in more diverse environments. Also, the length of tympanic bullae in M. australis was larger towards its northern distributional range (associated to smaller skulls), and smaller to the south (associated to larger skulls). Overall, the distributional range of both species coincided with unproductive environments, where temperature represents a limiting factor and, together with rainfall, might determine the observed morphological patterns.Fil: D'hiriart, Sofia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Teta, Pablo Vicente. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Cueto, Gerardo Ruben. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; Argentin

Global patterns of body size evolution are driven by precipitation in legless amphibians

This is the author accepted manuscript. The final version is available from Wiley via the DOI in this recordBody size shapes ecological interactions across and within species, ultimately influencing the evolution of large-scale biodiversity patterns. Therefore, macroecological studies of body size provide a link between spatial variation in selection regimes and the evolution of animal assemblages through space. Multiple hypotheses have been formulated to explain the evolution of spatial gradients of animal body size, predominantly driven by thermal (Bergmann's rule), humidity (‘water conservation hypothesis’) and resource constraints (‘resource rule’, ‘seasonality rule’) on physiological homeostasis. However, while integrative tests of all four hypotheses combined are needed, the focus of such empirical efforts needs to move beyond the traditional endotherm–ectotherm dichotomy, to instead interrogate the role that variation in lifestyles within major lineages (e.g. classes) play in creating neglected scenarios of selection via analyses of largely overlooked environment–body size interactions. Here, we test all four rules above using a global database spanning 99% of modern species of an entire Order of legless, predominantly underground-dwelling amphibians (Gymnophiona, or caecilians). We found a consistent effect of increasing precipitation (and resource abundance) on body size reductions (supporting the water conservation hypothesis), while Bergmann's, the seasonality and resource rules are rejected. We argue that subterranean lifestyles minimize the effects of aboveground selection agents, making humidity a dominant selection pressure – aridity promotes larger body sizes that reduce risk of evaporative dehydration, while smaller sizes occur in wetter environments where dehydration constraints are relaxed. We discuss the links between these principles with the physiological constraints that may have influenced the tropically-restricted global radiation of caecilians.Natural Environment Research Council (NERC)O2National Lottery - Big Lottery Fun

Scaling of the risk landscape drives optimal life history strategies and the evolution of grazing

Consumers face numerous risks that can be minimized by incorporating different life-history strategies. How much and when a consumer adds to its energetic reserves or invests in reproduction are key behavioral and physiological adaptations that structure much of how organisms interact. Here we develop a theoretical framework that explicitly accounts for stochastic fluctuations of an individual consumer's energetic reserves while foraging and reproducing on a landscape with resources that range from uniformly distributed to highly clustered. First, we show that optimal life-history strategies vary in response to changes in the mean productivity of the resource landscape, where depleted environments promote reproduction at lower energetic states, greater investment in each reproduction event, and smaller litter sizes. We then show that if resource variance scales with body size due to landscape clustering, consumers that forage for clustered foods are susceptible to strong Allee effects, increasing extinction risk. Finally, we show that the proposed relationship between consumer body size, resource clustering, and Allee effect-induced population instability offers key ecological insights into the evolution of large-bodied grazing herbivores from small-bodied browsing ancestors.Comment: 9 pages, 5 figures, 3 Supplementary Appendices, 2 Supplementary Figure

Rensch’s and Bergmann’s Rules in Cis-Andean South-American Howler Monkeys (Mammalia: Alouatta)

Howler monkeys (genus Alouatta) are large folivorous primates living in South America. We tested for the application of both Rensch’s rule and Bergmann’s rule to body size variation in Alouatta. We found that Rensch’s rule does apply in howlers. In Alouatta, males exploit dominance rank competition, and take advantage from seasonal abundance of high nutritious fruit supply in their diet. This mating system and dietary charateristics suggest positive male selection for body size is responsible for Rensch’s rule. However, since folivory favors large body size in primates (to lower mass specific metabolic rate) and it is the primary dietary habitus in howlers, larger species do occur in the Amazon basin, originating a reversed Bergmann’s rule pattern for both males and females at the interspecific level. The spatial and phylogenetic components of such body size patterns of variation are both important, implying Alouatta ecomorphological differences to occur above the species level, justifying their non-overlapping geographic distribution

Body-mass estimation from Middle Pleistocene fallow deer of Europe

• Analysis of a sample covering a period of time ranging from 700,000 to 250,000 years ago. • Body mass comparison between fallow deer species of the Middle Pleistocene. • Comparison of the overall averages obtained for each site considered. • Considerations on the correlation between size variability and climatic situation

Mammalian body size evolution was shaped by habitat transitions as an indirect effect of climate change

Aim: Body size evolution has long been hypothesized to have been driven by factors linked to climate change, but the specific mechanisms are difficult to disentangle due to the wide range of functional traits that covary with body size. In this study, we investigated the impact of regional habitat changes as a potential indirect effect of climate change on body size evolution. Location: Europe and North America. Time period: The Neogene (similar to 23-2 million years ago). Major taxa: Five orders of terrestrial mammals: Artiodactyla, Carnivora, Perissodactyla, Proboscidea and Primates. Methods: We compared the two continental faunas, which have exceptional fossil records of terrestrial mammals and underwent different processes of habitat transition during the Neogene. Using Bayesian multilevel regression models, we assessed the variation in the temporal dynamics of body size diversity among ecographic groups, defined by their continent of occurrence and dietary preference. Results: Model comparisons unanimously supported a combined effect of diet and continent on all metrics of body size frequency distributions, rejecting the shared energetic advantage of larger bodies in colder climates as a dominant mechanism of body size evolution. Rather, the diet-specific dynamics on each continent pinpointed an indirect effect of climate change - change in habitat availability, and thus the resource landscape as a key driver of mammalian evolution. Main conclusions: Our study highlights dietary preference as a mechanistic link between mammalian evolution and habitat transition mediating an indirect climate-change effect and demonstrates the complexity of climatic influence on biodiversity. Our findings suggest that the intensified habitat modification today likely poses a bigger threat than climate change in itself to living mammals, and perhaps all endotherms.Peer reviewe

Variabilitas Musiman Jenis Mamalia Di Kawasan Industri Semen PT Indocement Tunggal Prakarsa TBK Unit Palimanan, Jawa Barat

A study on seasonal variability of mammals species was carried out in the cement industrial area of PT Indocement Tunggal Prakarsa Tbk. Palimanan Plant, West Jawa. The combined action of climatic factors and habitat types have an important contribution to the diversity of mammals. Season conditions in the cement industrial and quarry area can be divided into the dry and rainy seasons. Eight main habitat types are present in the region: the conservation area of Mount Blindis, tree stands within the factory area, tree stands outside the factory area, area surrounding the pool/artificial lake, area of Jatropha curcas plantation, buffer zone, shrubs, and paddy fields in the cement industrial area and quarry. The objective of this study was to compare the diversity of mammals based on the season and habitat types. Total of mammals found are 17 species, comprising 10 species of aerial mammals (bats) and 7 species of terrestrial mammals. We found that species richness in the dry and rainy season was significantly different (p = 0.000). Dry season is richer (13 species, 105 individuals) than rainy season (12 species, 93 individuals). Index of mammals species diversity in the dry season is H\u27=1.65±0.12 with evenness index J\u27=0.64; while the rainy season is H\u27=1.87±0.10 with evenness index J\u27=0.75. Communities similarities of mammals between the dry season with the rainy season is 64%