When studying the impacts of climate change, there is a tendency to select climate data from a small set of arbitrary time periods or climate windows (e.g., spring temperature). However, these ...arbitrary windows may not encompass the strongest periods of climatic sensitivity and may lead to erroneous biological interpretations. Therefore, there is a need to consider a wider range of climate windows to better predict the impacts of future climate change. We introduce the R package climwin that provides a number of methods to test the effect of different climate windows on a chosen response variable and compare these windows to identify potential climate signals. climwin extracts the relevant data for each possible climate window and uses this data to fit a statistical model, the structure of which is chosen by the user. Models are then compared using an information criteria approach. This allows users to determine how well each window explains variation in the response variable and compare model support between windows. climwin also contains methods to detect type I and II errors, which are often a problem with this type of exploratory analysis. This article presents the statistical framework and technical details behind the climwin package and demonstrates the applicability of the method with a number of worked examples.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Extreme climatic events (ECEs) are predicted to become more frequent as the climate changes. A rapidly increasing number of studies – though few on animals – suggest that the biological consequences ...of ECEs can be severe. However, ecological research on the impacts of ECEs has been limited by a lack of cohesiveness and structure. ECEs are often poorly defined and have often been confusingly equated with climatic variability, making comparison between studies difficult. In addition, a focus on short‐term studies has provided us with little information on the long‐term implications of ECEs, and the descriptive and anecdotal nature of many studies has meant it is still unclear what the key research questions are. Synthesizing the current state of work is essential to identify ways to make progress. We conduct a synthesis of the literature and discuss conceptual and practical challenges faced by research on ECEs. We consider three steps to advance research. First, we discuss the importance of choosing an ECE definition and identify the pros and cons of ‘climatological’ and ‘biological’ definitions of ECEs. Secondly, we advocate research beyond short‐term descriptive studies to address questions concerning the long‐term implications of ECEs, focussing on selective pressures and phenotypically plastic responses and how they might differ from responses to a changing climatic mean. Finally, we encourage a greater focus on multi‐event studies that help us understand the implications of changing patterns of ECEs, through the combined use of modelling, experimental and observational field studies. This study aims to open a discussion on the definitions, questions and methods currently used to study ECEs, which will lead to a more cohesive approach to future ECE research.
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BFBNIB, FZAB, GIS, IJS, INZLJ, KILJ, NLZOH, NMLJ, NUK, OILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK, ZRSKP
Learning from single extreme events Altwegg, Res; Visser, Vernon; Bailey, Liam D. ...
Philosophical transactions - Royal Society. Biological sciences,
06/2017, Volume:
372, Issue:
1723
Journal Article
Peer reviewed
Open access
Extreme climatic events (ECEs) have a disproportionate effect on ecosystems. Yet much of what we know about the ecological impact of ECEs is based on observing the effects of single extreme events. ...We examined what characteristics affect the strength of inference that can be drawn from single-event studies, which broadly fell into three categories: opportunistic observational studies initiated after an ECE, long-term observational studies with data before and after an ECE and experiments. Because extreme events occur rarely, inference from such single-event studies cannot easily be made under the usual statistical paradigm that relies on replication and control. However, single-event studies can yield important information for theory development and can contribute to meta-analyses. Adaptive management approaches can be used to learn from single, or a few, extreme events. We identify a number of factors that can make observations of single events more informative. These include providing robust estimates of the magnitude of ecological responses and some measure of climatic extremeness, collecting ancillary data that can inform on mechanisms, continuing to observe the biological system after the ECE and combining observational data with experiments and models. Well-designed single-event studies are an important contribution to our understanding of biological effects of ECEs.
This article is part of the themed issue ‘Behavioural, ecological and evolutionary responses to extreme climatic events’.
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BFBNIB, NMLJ, NUK, PNG, SAZU, UL, UM, UPUK
Summary
Ecologists and many evolutionary biologists relate the variation in physiological, behavioural, life‐history, demographic, population and community traits to the variation in weather, a key ...environmental driver. However, identifying which weather variables (e.g. rain, temperature, El Niño index), over which time period (e.g. recent weather, spring or year‐round weather) and in what ways (e.g. mean, threshold of temperature) they affect biological responses is by no means trivial, particularly when traits are expressed at different times among individuals.
A literature review shows that a systematic approach for identifying weather signals is lacking and that the majority of studies select weather variables from a small number of competing hypotheses that are founded on unverified a priori assumptions. This is worrying because studies that investigate the nature of weather signals in detail suggest that signals can be complex. Using suboptimal or wrongly identified weather signals may lead to unreliable projections and management decisions.
We propose a four‐step approach that allows for more rigorous identification and quantification of weather signals (or any other predictor variable for which data are available at high temporal resolution), easily implementable with our new R package ‘climwin’. We compare our approach with conventional approaches and provide worked examples.
Although our more exploratory approach also has some drawbacks, such as the risk of overfitting and bias that our simulations show can occur at low sample and effect sizes, these issues can be addressed with the right knowledge and tools.
By developing both the methods to fit critical weather windows to a wide range of biological responses and the tools to validate them and determine sample size requirements, our approach facilitates the exploration and quantification of the biological effects of weather in a rigorous, replicable and comparable way, while also providing a benchmark performance to compare other approaches to.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The acute phase response (APR) is an evolutionarily well-conserved part of the innate immune defense against pathogens. However, recent studies in bats yielded surprisingly diverse results compared ...to previous APR studies on both vertebrate and invertebrate species. This is especially interesting due to the known role of bats as reservoirs for viruses and other intracellular pathogens, while being susceptible to extracellular microorganisms such as some bacteria and fungi. To better understand these discrepancies and the reservoir-competence of bats, we mimicked bacterial, viral and fungal infections in greater mouse-eared bats (Myotis myotis) and quantified different aspects of the APR over a two-day period. Individuals reacted most strongly to a viral (PolyI:C) and a bacterial (LPS) antigen, reflected by an increase of haptoglobin levels (LPS) and an increase of the neutrophil-to-lymphocyte-ratio (PolyI:C and LPS). We did not detect fever, leukocytosis, body mass loss, or a change in the overall functioning of the innate immunity upon challenge with any antigen. We add evidence that bats respond selectively with APR to specific pathogens and that the activation of different parts of the immune system is species-specific.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Large numbers of bats are killed by wind turbines globally, yet the specific demographic consequences of wind turbine mortality are still unclear. In this study, we compared characteristics of ...Nathusius' pipistrelles (Pipistrellus nathusii) killed at wind turbines (N = 119) to those observed within the live population (N = 524) during the summer migration period in Germany. We used generalized linear mixed‐effects modeling to identify demographic groups most vulnerable to wind turbine mortality, including sex (female or male), age (adult or juvenile), and geographic origin (regional or long‐distance migrant; depicted by fur stable hydrogen isotope ratios). Juveniles contributed with a higher proportion of carcasses at wind turbines than expected given their frequency in the live population suggesting that juvenile bats may be particularly vulnerable to wind turbine mortality. This effect varied with wind turbine density. Specifically, at low wind turbine densities, representing mostly inland areas with water bodies and forests where Nathusius' pipistrelles breed, juveniles were found more often dead beneath turbines than expected based on their abundance in the live population. At high wind turbine densities, representing mostly coastal areas where Nathusius' pipistrelles migrate, adults and juveniles were equally vulnerable. We found no evidence of increased vulnerability to wind turbines in either sex, yet we observed a higher proportion of females than males among both carcasses and the live population, which may reflect a female bias in the live population most likely caused by females migrating from their northeastern breeding areas migrating into Germany. A high mortality of females is conservation concern for this migratory bat species because it affects the annual reproduction rate of populations. A distant origin did not influence the likelihood of getting killed at wind turbines. A disproportionately high vulnerability of juveniles to wind turbine mortality may reduce juvenile recruitment, which may limit the resilience of Nathusius' pipistrelles to environmental stressors such as climate change or habitat loss. Schemes to mitigate wind turbine mortality, such as elevated cut‐in speeds, should be implemented throughout Europe to prevent population declines of Nathusius' pipistrelles and other migratory bats.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Anthropogenic activity can have substantial effects on wildlife. These effects may vary according to the characteristics of the activity and the species involved. Although effects on behaviour are ...well studied, studies of effects on fitness and physiology are scarce, particularly for group‐living species.
We exploited a natural experimental setup to investigate the effect of diurnal pastoralism on juvenile recruitment and allostatic load in a population of free‐ranging spotted hyenas in the Ngorongoro Crater, Tanzania, over a 24‐year period.
Pastoralism was restricted to the territories of two of the eight study clans, allowing us to compare juvenile recruitment in exposed and unexposed clans. We also compared faecal glucocorticoid metabolite concentrations (fGMC)—a biomarker of an organism's allostatic load—between exposed and unexposed clans using 975 faecal samples from 475 hyenas.
We found no detectable difference in juvenile recruitment nor fGMC between the exposed and unexposed clans, indicating that the pastoralism had no substantial deleterious effect on the spotted hyenas. The lack of a deleterious effect likely stems from the combined effect of the predictable and undisruptive nature of the pastoralism, the socio‐ecology of spotted hyenas and the Ngorongoro Crater's consistently abundant prey.
Our findings demonstrate that exposure to anthropogenic activity may be compatible with the persistence of certain group‐living species, especially if the overlap between the species' critical behaviours and the activity is limited. Our study thereby provides new perspectives for ecologists, conservation biologists and stakeholders who seek to assess human–wildlife conflicts and balance the needs of local human communities and wildlife.
Muhtasari
Shughuli za kibinadamu zinaweza kuwa na athari kubwa kwa wanyamapori. Athari hizi huweza kutofautiana kutokana na aina ya shughuli na tabia ya wanyamapori husika. Ingawa athari za kitabia zimetafitiwa vizuri, tafiti katika utimamu wa mwili na fiziolojia ni chache hasa katika spishi zinazoishi katika makundi.
Tulifanya majaribio kuchunguza athari za ufugaji wa kila siku katika ukuaji wa watoto na athari za mkazo kwa idadi ya fisi madoa doa huru katika eneo la Kreta ya Ngorongoro kwa kipindi cha miaka 24.
Ufugaji katika eneo la Kreta ulidhibitiwa kuwa katika mipaka ya koo mbili tu kati ya nane za kitafiti, hivyo kuturuhusu kulinganisha ukuaji wa watoto kati ya koo ambazo ufugaji ulifikia na zile ambazo ufugaji haukuathiri. Vile vile, tulilinganisha kiwango cha metabolite ya glukokotikoidi katika kinyeshi (fGMC), ambacho ni kiashiria cha mkazo kwa wanyama kati ya koo zilizofikiwa na ufugaji na zile ambazo hazikufikiwa kwa kutumia sampuli 975 za kinyesi kutoka kwa fisi madoa 475.
Hatukupata tofauti ya wazi katika ukuaji wa watoto na mkazo kati ya koo zilizofikiwa na zile ambazo hazikufikiwa na ufugaji kuonyesha kuwa ufugaji haukuwa na athari hasi kwa fisi madoa. Kukosekana kwa athari hasi pengine kunatokana na athari mjumuiko za asili ya ufugaji kunakotabirika na usio na usumbufu, ikilojia‐jamii ya fisi madoa na uthabiti wa idadi kubwa ya mawindo ndani ya Kreta.
Matokeo ya utafiti wetu unaonesha kuwa, shughuli za kibinadamu zinaweza kuendana na kustahilimiliwa na aina fulani ya spishi zinazoishi katika makundi, hasa ikiwa muingiliano kati ya spishi na shughuli utadhibitiwa. Kwa hivyo, utafiti wetu unatoa mitizamo mipya kwa wana ikolojia, wana biolojia wa uhifadhi na washikadau katika kutathmini migogoro ya binadamu na wanyama na kuleta usawa kati ya mahitaji ya jamii za wanadamu na wanyamapori.
This study emphasizes the importance of interpreting the impact of anthropogenic activity in light of the socio‐ecology of the species of conservation interest. By measuring reproductive performance in terms of recruitment at the level of groups, the work offers a new perspective on the study of human–wildlife conflict.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
For the preservation of endangered felid species, epididymal sperm may be received from valuable individuals after castration or death and they need to be cryopreserved for storage. However, ...pregnancy rates with epididymal or cryopreserved sperm are lower than with ejaculated and non-frozen semen even if insemination is surgically performed into the oviduct.
To investigate whether equilibration, the first step of the cryopreservation procedure, has an impact on sperm-oviduct binding, we generated oviduct epithelial cell vesicles from isthmus segments of preovulatory domestic cats. Binding assays were performed with epididymal sperm in a cell culture medium (M199) without supplements, or after cooling to 15 °C in a freezing extender (TestG), supplemented with glycerol and the water-soluble fraction of hen’s egg yolk mainly comprising LDL. The sperm-oviduct binding was assessed both quantitatively and qualitatively (head or tail binding of sperm with active or inactive mitochondria).
Most of the bound sperm prepared in M199 had active mitochondria and were attached to the vesicles by their heads. In equilibrated samples, the proportion of bound sperm with active mitochondria and the proportion of head-bound spermatozoa were reduced. The total motility of the sperm after 1 h of incubation in the absence or presence of vesicles were also affected by the preparation (higher in equilibrated) and the incubation (lower in co-incubated), while mitochondrial activity was influenced just by the preparation. Obviously, LDL has a beneficial effect on sperm motility, but we suggest that it interferes with the molecular sperm-oviduct crosstalk and causes a reduced binding of “good” sperm.
•Feline isthmus epithelial cell-vesicles were used for sperm oviduct binding assays.•Equilibration in freezing extender changes oviduct binding of epididymal sperm.•Functional interaction seems to occur by head binding of viable sperm to oviduct.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The rate of adaptive evolution, the contribution of selection to genetic changes that increase mean fitness, is determined by the additive genetic variance in individual relative fitness. To date, ...there are few robust estimates of this parameter for natural populations, and it is therefore unclear whether adaptive evolution can play a meaningful role in short-term population dynamics. We developed and applied quantitative genetic methods to long-term datasets from 19 wild bird and mammal populations and found that, while estimates vary between populations, additive genetic variance in relative fitness is often substantial and, on average, twice that of previous estimates. We show that these rates of contemporary adaptive evolution can affect population dynamics and hence that natural selection has the potential to partly mitigate effects of current environmental change.
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