For many species, parental care critically affects offspring survival. But what drives animals to display parental behaviours towards young? In mammals, pregnancy-induced physiological ...transformations seem key in preparing the neural circuits that lead towards attraction (and reduced-aggression) to young. Beyond mammalian maternal behaviour, knowledge of the neural mechanisms that underlie young-directed parental care is severely lacking. We took advantage of a domesticated bird species, the Japanese quail, for which parental behaviour towards chicks can be induced in virgin non-reproductive adults through a sensitization procedure, a process that is not effective in all animals. We used the variation in parental responses to study neural transcriptomic changes associated with the sensitization procedure itself and with the outcome of the procedure (i.e., presence of parental behaviours). We found differences in gene expression in the hypothalamus and bed nucleus of the stria terminalis, but not the nucleus taeniae. Two genes identified are of particular interest. One is neurotensin, previously only demonstrated to be causally associated with maternal care in mammals. The other one is urocortin 3, causally demonstrated to affect young-directed neglect and aggression in mammals. Because our studies were conducted in animals that were reproductively quiescent, our results reflect core neural changes that may be associated with avian young-directed care independently of extensive hormonal stimulation. Our work opens new avenues of research into understanding the neural basis of parental care in non-placental species.
Urbanization is modifying previously pristine natural habitats and creating “new” ecosystems for wildlife. As a result, some animals now use habitat fragments or have colonized urban areas. Such ...animals are exposed to novel stimuli that they have not been exposed to in their evolutionary history. Some species have adapted to the challenges they face—a phenomenon known as synurbanization—while others have not. Here we present a review of the sublethal consequences of life in the city for wild vertebrates, and demonstrate that urban animals face an almost completely different set of physiological and behavioural challenges compared to their rural counterparts. We focus on the negative fitness-related impacts of urbanization, but also identify instances where there are benefits to wildlife. The effects of urbanization appear to be both species- and contextdependent, suggesting that although the field of urban ecology is far from nascent, we are still just beginning to understand how the intricacies of biodiversity on our planet are affected by our presence.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Animals often avoid novel objects, a behavior known as neophobia. We examined behavioral responses of captive European starlings to novel objects placed at their food dishes. Exposure occurred ...concurrently to food reintroduction following overnight fasting. Behavior was analyzed for 10 min via video recording. We expected an increase in avoidance behavior compared with trials in which food was reintroduced without a novel object. Seven of 10 novel objects increased latency to approach the dish. In contrast to our expectations, neither prior restraint nor exogenous corticosterone changed the neophobic response to novel objects. While exposure to a novel object increased approach latency, there was no additional effect of restraining animals in a cloth bag for 15 min before food reintroduction. Furthermore, the subcutaneous injection of corticosterone did not affect approach latency by itself, nor did it affect the response to a novel object. Finally, we expected repeated exposure to the same object to extinguishing the neophobic response, and that restraint stress would prevent habituation. Our results show that European starlings habituate rapidly to exposure to a novel object, as approach latency returned to baseline within three repeated exposures to the same object. When the repeated presentation of the object was combined with prior restraint, however, the latency to approach never returned to baseline. These results reveal that neophobia in starlings is object‐specific and that, while neither acute stress nor corticosterone directly affects the behavioral response to a novel object, acute stress appears to have a permissive effect on neophobia by inhibiting habituation.
Glucocorticoids are not directly involved with the response of European starlings to novel objects, however, corticosterone may play a permissive role in neophobia as prior restraint stress prevents habituation during repeated exposure to an object.
HIGHLIGHTS
Novel objects induce neophobic behavior in the European starlings
Neither restraint nor corticosterone, are directly involved in neophobia
Restraint before repeated exposure to novel objects prevents habituation
Recreational boating activity has the potential to generate noise pollution that may influence wild fish. Such noise may be particularly relevant to fish engaged in parental care (PC), where ...alterations in behaviour could influence individual fitness and productivity of fish populations.
Here, the PC behaviour of the freshwater largemouth bass (Micropterus salmoides) was examined to determine whether disturbance from boat noise altered paternal behaviour. Changes in nest‐tending and brood‐guarding behaviour were measured following exposure to noise treatments of 1‐min duration using underwater playbacks of recorded boat noises.
One experiment compared the behaviour of bass tending eggs before, during, and after exposure to high‐speed or idling combustion motors, or an electronic bow‐mounted trolling motor. No significant differences in the time on nest, number of pectoral fin beats, and number of turns between the pre‐treatment, treatment, and post‐treatment periods for all three motor types were observed.
A second experiment assessed the impacts of noise (high‐speed combustion motor only) on the behaviour of nesting bass across the development stages of offspring (i.e. egg, egg‐sac fry, and swim‐up fry). During the egg‐sac fry stage, nest‐guarding males turned significantly less on the nest during the noise treatment compared with the long‐term post‐treatment period, indicating a stage‐specific impact of boat noise on parental behaviour. The effect was transient, however, and limited to the period that the noise was present.
Given that PC and recreational boating activity tend to co‐occur in nearshore areas, prolonged or frequent repeated exposure of nesting fish to boat noise during the egg‐sac fry stage could have adverse consequences for fitness and reproductive output. Efforts to restrict recreational boating activity in the vicinity of fish engaged in PC (e.g. through the use of set‐backs) would be a risk‐averse approach to mitigating the effects of noise pollution on fish.
Neophobia is an animal's avoidance of novelty. Animals tend to respond to novel objects by increasing their latency to approach the objects, and they eventually habituate after repeated exposure by ...attenuating this increased approach latency. Interestingly, the physiological stress response does not appear to have a causal link to neophobia, although acute stress can prevent animals from habituating to novel objects, possibly through a permissive effect. Chronic stress can induce an anxiety‐like state in animals, while often disrupting the ability to respond to acute stress. We thus hypothesized that chronic stress may increase neophobia and tested this by inducing chronic stress in wild‐caught European starlings (Sturnus vulgaris). Four distinct anthropogenic stressors were administered daily for 30 min each in a randomized order for 21 days. We then evaluated whether exposure to chronic stress altered the latency to approach a novel object placed on or near a food dish presented after overnight fasting. Chronically stressed birds and nonstressed controls exhibited similar initial neophobic responses to novel objects and showed similar habituation in response to repeated exposure. However, when birds were exposed to 15 min of restraint before repeated exposure to the same object, habituation was eliminated in control birds (i.e., they continued to respond with neophobia), whereas chronically stressed birds continued to show habituation as measured by attenuated approach latencies. These results demonstrate that an acute stress response (restraint) has a different impact on neophobia depending upon whether the bird is or is not concurrently exposed to chronic stress.
Chronic stress attenuates the permissive role of corticosterone in neophobia in European starlings by eliminating the effect of acute stress on habituation during repeated exposure to an object.
Highlights
Chronic stress does not alter the magnitude of neophobia responses.
Chronic stress does not alter habituation to novel objects.
Restraint before repeated exposure to novel objects prevents habituation.
Chronic stress restores habituation following restraint.
Increased hemoglobin concentration (Hb) and hematocrit (Hct), attributable to spleen contraction, raise blood gas storage capacity during apnea, but the mechanisms that trigger this response have not ...been clarified. We focused on the role of hypoxia in triggering these Hb and Hct elevations. After horizontal rest for 20 min, 10 volunteers performed 3 maximal apneas spaced by 2 min, each preceded by a deep inspiration of air. The series was repeated using the same apneic durations but after 1 min of 100% oxygen (O
2
) breathing and O
2
inspiration prior to each apnea. Mean apneic durations were 150, 171, and 214 s for apneas 1, 2, and 3, respectively. Relative to pre-apnea values, the mean post-apneic arterial O
2
saturation nadir was 84.7% after the air trial and 98% after the O
2
trial. A more pronounced elevation of both Hb and Hct occurred during the air trial: after apnea 1 with air, mean Hb had increased by 1.5% (
P
< 0.01), but no clear increase was found after the first apnea with O
2
. After the third apnea with air Hb had increased by 3.0% (
P
< 0.01), and with O
2
by 2.0% (
P
< 0.01). After the first apnea with air Hct had increased by 1.9% (
P
< 0.01) and after 3 apneas by 3.0% (
P
< 0.01), but Hct did not change significantly in the O
2
trial. In both trials, Hb and Hct were at pre-apneic levels 10 min after apneas. Diving bradycardia during apnea was the same in both trials. We conclude that hypoxia contributes to spleen contraction during apnea, likely through chemosensor-related sympathetic output. There are, however other factors involved that trigger spleen contraction even in the absence of hypoxia.
•We review 385 studies assessing glucocorticoid responses to weather-related stimuli.•Included are field, captive, and laboratory studies from all major vertebrate taxa.•Acute exposures <24 h show ...strong support for eliciting glucocorticoid responses.•Exposures >24 h show weaker support, suggesting habituation in some species.•Results support glucocorticoids as a major mechanism to cope with inclement weather.
Changes in the environment related to inclement weather can threaten survival and reproductive success both through direct adverse exposure and indirectly by decreasing food availability. Glucocorticoids, released during activation of the hypothalamic-pituitary-adrenal axis as part of the stress response, are an important candidate for linking vertebrate coping mechanisms to weather. This review attempts to determine if there is a consensus response of glucocorticoids to exposure to weather-related stimuli, including food availability, precipitation, temperature and barometric pressure. The included studies cover field and laboratory studies for all vertebrate taxa, and are separated into four exposure periods, e.g., hours, days, weeks and months. Each reported result was assigned a score based on the glucocorticoid response, e.g., increased, no change, or decreased. Short-term exposure to weather-related stimuli, of up to 24 h, is generally associated with increased glucocorticoids (79% of studies), suggesting that these stimuli are perceived as stressors by most animals. In contrast, the pattern for exposures longer than 24 h shows more variation, even though a majority of studies still report an increase (64%). Lack of glucocorticoid increases appeared to result from instances where: (1) prolonged exposure was a predictable part of the life history of an animal; (2) environmental context was important for the ultimate effect of a stimulus (e.g., precipitation limited food availability in one environment, but increased food in another); (3) prolonged exposure induced chronic stress; and (4) long-term responses appeared to reflect adaptations to seasonal shifts, instead of to short-term weather. However, there is a strong bias towards studies in domesticated laboratory species and wild animals held in captivity, indicating a need for field studies, especially in reptiles and amphibians. In conclusion, the accumulated literature supports the hypothesis that glucocorticoids can serve as the physiological mechanism promoting fitness during inclement weather.
Repeated exposure to acute stressors causes dramatic changes in an animal's stress physiology and the cumulative effects are often called chronic stress. Recently we showed that short‐term exposure ...to weather‐related stimuli, such as temperature change, artificial precipitation, and food restriction, cause acute responses in captive European starlings (Sturnus vulgaris). Here, we examined the effect of repeated exposure to weather‐related stressors on heart rate and corticosterone (CORT) of captive non‐molting and molting European starlings. Four times every day for 3 weeks, birds were exposed to either 30 min of a subtle (3°C) decrease in temperature, a short bout of simulated rain, or 2 hr of food removal. The order and time of presentation were randomly assigned on each day. We found no differences in heart rate or heart rate variability. Furthermore, there were no changes in baseline CORT levels, CORT negative feedback efficacy, or maximal adrenal capacity. Mass increased across the experimental period only in molting birds. CORT responses to restraint were decreased in both groups following treatment, suggesting the birds had downregulated their responses to acute stress. Molting birds showed evidence of suppression of the HPA axis compared with non‐molting birds, which is consistent with previous research. Overall, our data show that repeated exposure to weather‐related stressors does not elicit most of the symptoms normally associated with chronic stress.
GRAPHICAL ABSTRACT
Repeated exposure to weather‐related stimuli does not induce chronic stress.
HPA axis is suppressed in molting birds.
Molt status does not affect response to repeated exposure to weather‐related stimuli.
Teaching can be a rewarding, yet challenging, experience for early career researchers (ECRs) in fields like ecology and evolution. Much of this challenge arises from the reality that ECRs in ecology ...and evolution typically receive little, if any, pedagogical training or advice on how to balance teaching, research (which can include extended field work), and other demands on their time. Here, we aim to provide accessible, pragmatic advice for ECRs in ecology and evolution who are given the opportunity to teach (as instructor of record). The advice is based on the authors’ collective experiences teaching in ecology and evolution as ECRs and is meant to help ECRs address two challenges: a) balancing the demands of teaching against one’s research, service, and personal life, and b) being effective in the classroom while doing so. The guidance we provide includes practical steps to take when teaching for the first time, including carefully refining the syllabus (course planning), adopting ‘non-traditional’ teaching methods, and taking advantage of free teaching resources. We also discuss a range of ‘soft skills’ to consider including guarding against imposter syndrome (i.e., self-doubt and fear of being exposed as a fraud), managing expectations, being empathetic, compassionate, authentic, and fostering an inclusive classroom. Lastly, we emphasize the need to focus on developing students’ critical thinking skills, integrating research and teaching where possible, and setting limits on class preparation time to maintain balance with your research and personal life. Collectively, we hope the examples provided herein offer a useful guide to ECRs new to teaching.
Glucocorticoids (GCs) are thought to impact reproductive success, and ultimately fitness. In this study we focus specifically on the relationship between GCs and parental care. Captive bred Japanese ...quail (Coturnix japonica) do not show spontaneous parental care behavior, however this behavior can be induced through a sensitization procedure. We investigated how the GC status of Japanese quail relates to parental care in animals of both sexes exposed or not to a chick sensitization treatment. To assess GC status, we obtained baseline plasma and feather cort samples, and used the HPA-axis function test to assess stress responsiveness by examining the response to a standardized stressor as well as negative feedback efficacy through dexamethasone injection. Next, birds were either exposed to chicks overnight in a small enclosure (sensitization treatment) or were enclosed but not exposed to chicks (control). The following morning, adult behaviors were filmed in the presence of a fresh set of chicks for 20 min. A final serum GC sample was obtained to assess if exposure to novel chicks was perceived as stressful. In control animals, baseline GCs were associated with increased total parental care duration and decreased latency to first parental care event. Interestingly, the opposite relationship was found in the sensitization group. Finally, exposure to novel chicks was not associated with an increase in corticosterone in either group. Overall it appears that baseline GCs are correlated with parental care in captive bred Japanese quail, and that the relationship changes direction depending on whether or not sensitization has occurred.
•Overnight exposure to chicks induces parental care behavior in Japanese quail.•Baseline corticosterone is positively associated with parental care in controls.•Baseline cort is negatively associated with parental care in sensitized quail.•Cort may play different roles in parental care depending on reproductive status.•Exposure to novel chicks does not elicit a stress response in Japanese quail.
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