Adaptive latitudinal variation in Common Blackbird Turdus merula nest characteristics

Nest construction is taxonomically widespread, yet our understanding of adaptive intraspecific variation in nest design remains poor. Nest characteristics are expected to vary adaptively in response to predictable variation in spring temperatures over large spatial scales, yet such variation in nest design remains largely overlooked, particularly amongst open-cup-nesting birds. Here, we systematically examined the effects of latitudinal variation in spring temperatures and precipitation on the morphology, volume, composition, and insulatory properties of open-cup-nesting Common Blackbirds’ Turdus merula nests to test the hypothesis that birds living in cooler environments at more northerly latitudes would build better insulated nests than conspecifics living in warmer environments at more southerly latitudes. As spring temperatures increased with decreasing latitude, the external diameter of nests decreased. However, as nest wall thickness also decreased, there was no variation in the diameter of the internal nest cups. Only the mass of dry grasses within nests decreased with warmer temperatures at lower latitudes. The insulatory properties of nests declined with warmer temperatures at lower latitudes and nests containing greater amounts of dry grasses had higher insulatory properties. The insulatory properties of nests decreased with warmer temperatures at lower latitudes, via changes in morphology (wall thickness) and composition (dry grasses). Meanwhile, spring precipitation did not vary with latitude, and none of the nest characteristics varied with spring precipitation. This suggests that Common Blackbirds nesting at higher latitudes were building nests with thicker walls in order to counteract the cooler temperatures. We have provided evidence that the nest construction behavior of open-cup-nesting birds systematically varies in response to large-scale spatial variation in spring temperatures

Bacteria and the evolution of honest signals. The case of ornamental throat feathers in spotless starlings

1. Mechanisms guaranteeing reliability of messages are essential in understanding the underlying information and evolution of signals. Micro-organisms may degrade signalling traits and therefore influence the transmitted information and evolution of these characters. The role of micro-organisms in animal signalling has, however, rarely been investigated. 2. Here, we explore a possible role for feather-degrading bacteria driving the design of ornamental throat feathers in male spotless starlings (Sturnus unicolor). We estimated length, bacterial load, degradation status and susceptibility to degradation by keratinolytic bacteria in those feathers, compared with non-ornamental adjacent feathers in males, as well as to throat feathers in females. In addition, the volume of the uropygial gland and its secretion was measured and the secretion extracted. We also experimentally evaluated the capacity of each secretion to inhibit growth of a keratinolytic bacterium. 3. The apical part of male ornamental throat feathers harboured more bacteria and degraded more quickly than the basal part; these patterns were not detected in female throat feathers or in non-ornamental male feathers. Moreover, degradation status of male and female throat feathers did not differ, but was positively associated with feather bacterial density. Finally, the size of the uropygial gland in both males and females predicted volume and the inhibitory capacity of secretion against feather-degrading bacteria. Only in males was uropygial gland size negatively associated with the level of feather degradation. 4. All results indicate differential susceptibility of different parts of throat feathers to keratinolytic bacterial attack, which supports the possibility that throat feathers in starlings reflect individual ability to combat feather-degrading bacteria honestly. This is further supported by the relationship detected between antimicrobial properties of uropygial secretion and the level of feather degradation. 5. Our results suggest that selection pressures exerted by feather-degrading bacteria on hosts may promote evolution of particular morphologies of secondary sexual traits with different susceptibility to bacterial degradation that reliably inform of their bacterial load. Those results will help to understand the evolution of ornamental signals.This work was financed by Spanish Ministerio de Ciencia e Innovaci on, European funds (FEDER) (CGL2010-19233-C03-01, CGL2013-48193-C3-1-P). MRR and DMG received a postdoc from the program “JAE-Doc”, GT from the “Juan de la Cierva”, and CRC had a predoctoral fellowship, all from the Spanish Government.Peer reviewe

A decrease in diet quality occurs during pregnancy in overweight and obese women which is maintained post-partum

BACKGROUND: Ensuring adequate dietary intake during pregnancy has important implications for optimising maternal and fetal health. It is not known whether diet quality is altered over pregnancy and the post-partum period. OBJECTIVE: The aim of this study was to perform a comprehensive assessment of diet quality in overweight and obese women during pregnancy and early post-partum. DESIGN: In a prospective cohort study, n=301 overweight or obese pregnant women completed a food frequency questionnaire at study entry (10–20 weeks gestation), 28 weeks gestation, 36 weeks gestation and 4 months post-partum for assessment of macronutrient and micronutrient intake and diet quality by the Healthy Eating Index (HEI). RESULTS: Energy, macronutrient and dietary sources of micronutrients did not alter across pregnancy or post-partum. The HEI was of below average quality in 31.0% of women at baseline. This decreased from week 28 (P<0.001) and was maintained at a lower level post-partum such that HEI levels were lower compared with study entry (53.3±12.7 versus 56.7±10.1, P<0.001). The HEI decrease occurred in association with decreases in the milk, meat and unsaturated oil components, and increases in the proportion of energy from solid fats, alcohol and added sugars (P<0.001), and was independently predicted by the socioeconomic index for areas score (β=−0.011, s.e.=0.011, P=0.031). CONCLUSION: We report for the first time that dietary quality decreases across pregnancy and is maintained at this reduced level in the early post-partum period in overweight and obese women. Dietary interventions aimed at improving diet quality should be targeted to early pregnancy and post-partum.L.J. Moran, Z. Sui, C.S. Cramp and J.M. Dod

Population change in breeding boreal waterbirds in a 25-year perspective : What characterises winners and losers?

Understanding drivers of variation and trends in biodiversity change is a general scientific challenge, but also crucial for conservation and management. Previous research shows that patterns of increase and decrease are not always consistent at different spatial scales, calling for approaches combining the latter. We here explore the idea that functional traits of species may help explaining divergent population trends. Complementing a previous community level study, we here analyse data about breeding waterbirds on 58 wetlands in boreal Fennoscandia, covering gradients in latitude as well as trophic status. We used linear mixed models to address how change in local abundance over 25 years in 25 waterbird species are associated with life history traits, diet, distribution, breeding phenology, and habitat affinity. Mean abundance increased in 10 species from 1990/1991 to 2016, whereas it decreased in 15 species. Local population increases were associated with species that are early breeders and have small clutches, an affinity for luxurious wetlands, an herbivorous diet, and a wide breeding range rather than a southern distribution. Local decreases, by contrast, were associated with species having large clutches and invertivorous diet, as well as being late breeders and less confined to luxurious wetlands. The three species occurring on the highest number of wetlands all decreased in mean abundance. The fact that early breeders have done better than late fits well with previous research about adaptability to climate change, that is, response to earlier springs. We found only limited support for the idea that life history traits are good predictors of wetland level population change. Instead, diet turned out to be a strong candidate for an important driver of population change, as supported by a general decrease of invertivores and a concomitant increase of large herbivores. In a wider perspective, future research needs to address whether population growth of large-bodied aquatic herbivores affects abundance of co-occurring invertivorous species, and if so, if this is due to habitat alteration, or to interference or exploitative competition.Peer reviewe

Conservation physiology and the COVID-19 pandemic

The COVID-19 pandemic and associated public health measures have had unanticipated effects on ecosystems and biodiversity. Conservation physiology and its mechanistic underpinnings are well positioned to generate robust data to inform the extent to which the Anthropause has benefited biodiversity through alterations in disturbance-, pollution- and climate change-related emissions. The conservation physiology toolbox includes sensitive biomarkers and tools that can be used both retroactively (e.g. to reconstruct stress in wildlife before, during and after lockdown measures) and proactively (e.g. future viral waves) to understand the physiological consequences of the pandemic. The pandemic has also created new risks to ecosystems and biodiversity through extensive use of various antimicrobial products (e.g. hand cleansers, sprays) and plastic medical waste. Conservation physiology can be used to identify regulatory thresholds for those products. Moreover, given that COVID-19 is zoonotic, there is also opportunity for conservation physiologists to work closely with experts in conservation medicine and human health on strategies that will reduce the likelihood of future pandemics (e.g. what conditions enable disease development and pathogen transfer) while embracing the One Health concept. The conservation physiology community has also been impacted directly by COVID-19 with interruptions in research, training and networking (e.g. conferences). Because this is a nascent discipline, it will be particularly important to support early career researchers and ensure that there are recruitment pathways for the next generation of conservation physiologists while creating a diverse and inclusive community. We remain hopeful for the future and in particular the ability of the conservation physiology community to deliver relevant, solutions-oriented science to guide decision makers particularly during the important post-COVID transition and economic recovery

Use of a DVD to provide dietary and lifestyle information to pregnant women who are overweight or obese: a nested randomised trial

Background: We conducted a nested randomised trial to evaluate the effect of an educational DVD, providing information about healthy food choices and exercise during pregnancy, on diet and physical activity, among pregnant women who were overweight or obese. Methods: We conducted a nested randomised trial within the context of the LIMIT randomised trial. Women were eligible with a singleton pregnancy between 10 and 20 weeks gestation, and body mass index at the time of their first antenatal appointment of ≥25 kg/m2. All women who were randomised to the Lifestyle Advice Group of the LIMIT trial received a series of consultations with both research dieticians and research assistants, in addition to standard written dietary and exercise materials (Standard Materials Group). Women randomised to the DVD Group received the same consultations and written materials, and additionally received an educational DVD (DVD Group). The primary study outcome was the Healthy Eating Index. Other study outcomes included physical activity, and gestational weight gain. Women completed a qualitative evaluation of all the materials provided. Results: 1,108 women in the LIMIT Lifestyle Advice Group participated in the nested trial, with 543 women randomised to the DVD Group, and 565 women to the Standard Materials Group. Women who received the DVD compared with those who did not, had a higher mean Healthy Eating Index at 36 weeks gestation (73.6 vs 72.3; adjusted mean difference 1.2; 95% CI 0.2 to 2.3; p = 0.02), but not at 28 weeks gestation (73.2 vs 73.5; adjusted mean difference −0.1; 95% CI −1.1 to 0.9; p = 0.82). There were no statistically significant differences in physical activity or total gestational weight gain. While most women evaluated the materials positively, frequency of utilisation was poor. Conclusions: Ongoing attention to the delivery of information is required, particularly with the increased use and availability of digital and multi-media interactive technologies.Malgorzata A Szmeja, Courtney Cramp, Rosalie M Grivell, Andrea R Deussen, Lisa N Yelland and Jodie M Dod

Use of materials in nest construction by Pied Flycatchers Ficedula hypoleuca reflects localised habitat and geographical location.

Capsule Pied Flycatchers use different materials to construct their nests according to localised habitat and geographical location. Aims This study tested the hypotheses that birds would use the leaves they normally encountered within their breeding territories and that nest composition varied between geographical locations. Methods In Lancashire, Pied Flycatcher nests were collected from nestboxes built in locations dominated by different tree species and were deconstructed to determine which materials were used. Results Materials found in nests generally reflected the localised habitat around the nest rather than showing evidence of active collection from distant sources of material. Nests from Lancashire were significantly different in composition when compared with published data for nests from north Wales and central Spain. The use of moss was dominated by the use of one species in all but two nests. Conclusion Pied Flycatchers exhibit plasticity in nest construction behaviour because they were opportunistic in their choice of most nesting materials although they may be selective in their choice of moss

Decreased hydrogen peroxide production and mitochondrial respiration in skeletal muscle but not cardiac muscle of the green-striped burrowing frog, a natural model of muscle disuse

Suppression of disuse-induced muscle atrophy has been associated with altered mitochondrial reactive oxygen species (ROS) production in mammals. However, despite extended hindlimb immobility, aestivating animals exhibit little skeletal muscle atrophy compared with artificially immobilised mammalian models. Therefore, we studied mitochondrial respiration and ROS (H2O2) production in permeabilised muscle fibres of the green-striped burrowing frog, Cyclorana alboguttata. Mitochondrial respiration within saponin-permeabilised skeletal and cardiac muscle fibres was measured concurrently with ROS production using high-resolution respirometry coupled to custom-made fluorometers. After 4 months of aestivation, C. alboguttata had significantly depressed whole-body metabolism by similar to 70% relative to control (active) frogs, and mitochondrial respiration in saponin-permeabilised skeletal muscle fibres decreased by almost 50% both in the absence of ADP and during oxidative phosphorylation. Mitochondrial ROS production showed up to an 88% depression in aestivating skeletal muscle when malate, succinate and pyruvate were present at concentrations likely to reflect those in vivo. The percentage ROS released per O-2 molecule consumed was also similar to 94% less at these concentrations, indicating an intrinsic difference in ROS production capacities during aestivation. We also examined mitochondrial respiration and ROS production in permeabilised cardiac muscle fibres and found that aestivating frogs maintained respiratory flux and ROS production at control levels. These results show that aestivating C. alboguttata has the capacity to independently regulate mitochondrial function in skeletal and cardiac muscles. Furthermore, this work indicates that ROS production can be suppressed in the disused skeletal muscle of aestivating frogs, which may in turn protect against potential oxidative damage and preserve skeletal muscle structure during aestivation and following arousal

‘O sibling, where art thou?’ – a review of avian sibling recognition with respect to the mammalian literature

Avian literature on sibling recognition is rare compared to that developed by mammalian researchers. We compare avian and mammalian research on sibling recognition to identify why avian work is rare, how approaches differ and what avian and mammalian researchers can learn from each other. Three factors: (1) biological differences between birds and mammals, (2) conceptual biases and (3) practical constraints, appear to influence our current understanding. Avian research focuses on colonial species because sibling recognition is considered adaptive where ‘mixing potential’ of dependent young is high; research on a wider range of species, breeding systems and ecological conditions is now needed. Studies of acoustic recognition cues dominate avian literature; other types of cues (e.g. visual, olfactory) deserve further attention. The effect of gender on avian sibling recognition has yet to be investigated; mammalian work shows that gender can have important influences. Most importantly, many researchers assume that birds recognise siblings through ‘direct familiarisation’ (commonly known as associative learning or familiarity); future experiments should also incorporate tests for ‘indirect familiarisation’ (commonly known as phenotype matching). If direct familiarisation proves crucial, avian research should investigate how periods of separation influence sibling discrimination. Mammalian researchers typically interpret sibling recognition in broad functional terms (nepotism, optimal outbreeding); some avian researchers more successfully identify specific and testable adaptive explanations, with greater relevance to natural contexts. We end by reporting exciting discoveries from recent studies of avian sibling recognition that inspire further interest in this topic

A pathogenic skin fungus and sloughing exacerbate cutaneous water loss in amphibians

Batrachochytrium dendrobatidis (Bd) is a pathogenic fungus that causes the cutaneous, infectious disease chytridiomycosis and has been implicated in population declines of numerous anuran species worldwide. Proximate cause of death by chytridiomycosis is asystolic cardiac arrest as a consequence of severe disruption to electrolyte balance. Animals heavily infected with Bd also experience a disruption to their skin sloughing regime, indicating that core functions of the skin, such as water retention, may be severely impacted. This study examined how skin sloughing, body size and Bd infection interact to influence water loss rates in five Australian frog species: Litoria caerulea, Limnodynastes peronii, Lechriodus fletcheri, Limnodynastes tasmaniensis and Platyplectrum ornatum. Rates of water loss more than doubled during sloughing in L. caerulea. During active periods across all species, water loss rates were on average 232% higher in Bd infected frogs than in uninfected frogs. This indicates that dehydration stress may be a significant factor contributing to the morbidity of severely Bd infected anurans, a symptom that is then exacerbated by an increased rate of sloughing. When taking size into account, smaller and/or juvenile anurans may be more at risk from dehydration due to Bd infection, as they lose a greater amount of water and slough more frequently than adults. This may in part explain the higher mortality rates typical for small and juvenile frogs infected with Bd. Understanding how Bd affects the core functions of the skin, including rates of water loss, can improve our predictions of disease outcome in amphibians