Daily temporal organization of laying in Japanese quail: variability and heritability

In birds, many behavioral and physiological processes that occur during reproduction show daily rhythms in response to environmental temporal constraints. In this study, the individual daily organization of laying and its genetic determinant in Japanese quail (Coturnix coturnix japonica) were analyzed. For this purpose, the oviposition time of 102 randomly chosen females, maintained in long-day photoperiodic conditions (LD 14h:10h) for 1 mon was observed and extreme phenotypes selected. Laying is characterized by two parameters: oviposition interval and laying hour.

The birds showed a specific time of laying during 24 h. All eggs were laid in the afternoon between 6.5 and 14 h after lights on (HALO). Two laying profiles were determined: 20% of females with an oviposition interval greater than 24 h (24.7±0.2 h) (the “delayed” profile) laid progressively later each day until a pause day. The remaining 80% of the females laid at the same time each day, with few pause days and an oviposition interval close to 24 h (24.0±0.2 h) (the “stable” profile). Among the females, showing this last profile, an intra-individual stability and an inter-individual variability of laying hour was established. Two extreme laying phenotypes were then determined: the “early” phenotype (E) for females laying on average between 7.5 and 9.5 HALO and the “late” phenotype (L) for females laying between 12.5 and 14 HALO.

In order to study the genetic basis of the laying hour, three females of each extreme phenotype were selected and crossed with two different males. The E and L females produced 57 F1E and 42 F1L daughters, respectively. F1 females displayed both laying profiles. However, the proportion of females displaying a “delayed” profile was higher in the L line (50%) than in the E line (29.8%). For the “stable” daughters, artificial selection induced an advance in laying hour of 4.7% for the E line and a delay of 4.7% for the L line. Realized heritability was estimated at 0.5. Moreover, the laying hour of the daughters was correlated positively to that of the mothers (N=61;r=0.45). These results support the notion of heritability of oviposition time in Japanese quail.     

Daily temporal organization of laying in Japanese quail: variability and heritability

In birds, many behavioral and physiological processes that occur during reproduction show daily rhythms in response to environmental temporal constraints. In this study, the individual daily organization of laying and its genetic determinant in Japanese quail (Coturnix coturnix japonica) were analyzed. For this purpose, the oviposition time of 102 randomly chosen females, maintained in long-day photoperiodic conditions (LD 14h:10h) for 1 mon was observed and extreme phenotypes selected. Laying is characterized by two parameters: oviposition interval and laying hour.

The birds showed a specific time of laying during 24 h. All eggs were laid in the afternoon between 6.5 and 14 h after lights on (HALO). Two laying profiles were determined: 20% of females with an oviposition interval greater than 24 h (24.7±0.2 h) (the “delayed” profile) laid progressively later each day until a pause day. The remaining 80% of the females laid at the same time each day, with few pause days and an oviposition interval close to 24 h (24.0±0.2 h) (the “stable” profile). Among the females, showing this last profile, an intra-individual stability and an inter-individual variability of laying hour was established. Two extreme laying phenotypes were then determined: the “early” phenotype (E) for females laying on average between 7.5 and 9.5 HALO and the “late” phenotype (L) for females laying between 12.5 and 14 HALO.

In order to study the genetic basis of the laying hour, three females of each extreme phenotype were selected and crossed with two different males. The E and L females produced 57 F1E and 42 F1L daughters, respectively. F1 females displayed both laying profiles. However, the proportion of females displaying a “delayed” profile was higher in the L line (50%) than in the E line (29.8%). For the “stable” daughters, artificial selection induced an advance in laying hour of 4.7% for the E line and a delay of 4.7% for the L line. Realized heritability was estimated at 0.5. Moreover, the laying hour of the daughters was correlated positively to that of the mothers (N=61;r=0.45). These results support the notion of heritability of oviposition time in Japanese quail.     

Moulting cycles in European quail (Coturnix coturnix coturnix) under constant photoperiodic conditions

Abstract

Male and female European quails (Coturnix coturnix coturnix) were studied whilst being maintained in LD 12:12, at 20° C, for four years from birth. The birds exhibited the following phases: end of the first phase of the post‐juvenile moult, fattening and a period of nocturnal activity. Then sexual development is observed up to complete maturation at the age of four months. The second part of post juvenile moulting occurs towards the age of 5 to 6 months. During the following 6 months an important phase of reproduction is observed, thus completing their first year of life. The same sequence is repeated during the following years: a moult which lasts for 6 months in two (sometimes three) partial phases separated by episodes of reproduction; then an important period of reproduction (6 months) without moulting. The birds are capable of reproducing at all times except during moulting. The sequence of moulting begins each year in the same months as those for natural French populations. It thus seems that the annual periodicity and the organisation itself of the phenomenon of moulting is controlled in European quail by an endogenous circannual rhythm. In contrast, the natural cyclic expression of sexuality appears to be dependent on abiotic environmental and social factors.     

Circadian control of migratory restlessness and the effects of exogenous melatonin in the brambling, Fringilla montifringilla

Circadian pacemakers control both “daytime” activity and nocturnal restlessness of migratory birds, and the daily rhythm of melatonin release from the pineal has been suggested to be involved in the control of migratory activity. To study the phase relations between the two activity components during entrainment and when free running, locomotor activity of bramblings (Fringilla montifringilla) was recorded continuously under a 12:12 “cool light” to “warm light” cycle (CL:WL, ca. 5000 K and ca. 2500 K, respectively) or blue light to red light cycle (BL:RL, maxima at 440 and 650 nm, respectively) at different irradiance ratios. Migratory activity was expressed primarily during the WL or RL phase of the light cycles. Under free-running conditions, the circadian periods τ correlated with the phase relations between day and night (migratory) activity components during preceding entrainment. Bramblings with migratory activity had significantly longer τ at constant light intensity than the same individuals without migratory activity. Birds with migratory activity reentrained faster after a 6h phase shift of the CL:WL cycle than birds without migratory activity. When exogenous melatonin was given in the drinking water (200 μg/mL 1% ethanol or 0.86 mM) to bramblings exposed to 12:12 CL:WL cycles with constant irradiance, the amounts of activity, which were initially higher during the WL phase of the light cycle, were suppressed to similar low levels during both light phases. The systematic changes in the amounts of activity during melatonin treatment were not correlated with consistent changes in entrainment status. The data support the hypothesis that changes in the amplitude and level of the daily melatonin cycle are involved in regulating migratory restlessness, by either allowing or inhibiting nocturnal activity. (Chronobiology International, 17(4), 471-488, 2000)     

Evolutionary aspects of migratory behavior in European warblers

During the past 20 years, European Sylvia warblers have been used for a model study of the control mechanisms of bird migration and of evolutionary aspects of migratory behavior. Endogenous annual rhythms (‘circannual’ rhythms) and photo-period have proved to be the essential internal and external controlling factors. It is unknown whether this basic system, that also controls migration in other bird species, is currently evolutionarily stable or is instead adapting birds to the present slightly changing environmental conditions. Using the Blackcap, the control of partial migration in a bird species was analyzed. Two-way selective breeding experiments demonstrated a large selection response and high heritability values. These experiments have also indicated that a partially migratory population can become either almost completely migratory, or sedentary, in two to five generations. Hence, genetic influences are very important and presumably dominant over environmental factors in the expression of migratory or sedentary behavior. The large selection response implies a strikingly high evolutionary potential with respect to strong selection pressures. Further, in the Blackcap, migratory orientation behavior (in addition to migratory activity) was immediately transmitted into a F₁-generation when a cross-breeding experiment was performed using birds from a migratory and a resident population. The hybrids displayed their migratory activity along an axis that is used by their migratory parents. Finally, a rapidly developing novel migratory habit (new migratory direction to new wintering areas) in the Blackcap is discussed with respect to a positive feedback-mechanism, possibly including a series of advantages leading to above-average fitness.     

Suppression of nocturnal increases in levels of melatonin elicits an anticipatory behavior in male quail

Abstract

During the reproductive development of male Japanese quail the duration of daily activity is prolonged and the onset of the rhythm of activity is advanced relative to the light‐dark cycle. The neuroendocrine basis for these changes was investigated with focusing on plasma levels of melatonin and testosterone. By means of 4 additional hours of photic stimulation of the brain, after the environmental lights (8L: 16D, lights on at 1000 hr) were turned off, the increase in levels of melatonin after lights‐off was suppressed for a few days. Thereafter the early onset of daily locomotor activity was observed and the gonads began to develop. Similar behavioral changes occurred in castrated quail following direct brain‐illumination or testosterone implants. The testosterone implants also suppressed the increases in levels of melatonin after lights‐off, for a few days. Treatment with an antiserum raised against melatonin (anti‐M) for the first 3 days, to suppress the increases in levels of melatonin after lights‐off, elicited such an anticipatory behavior. These results suggest that suppression of the nocturnal rise in melatonin levels is important for the first steps toward reproductive activity in male Japanese quail.     

Effect of a cranium-directed daily illumination cycle on the laying rhythm in Japanese quail

This study tests the effect on the laying rhythm of a light cycle reaching directly the encephala via a diode in Japanese quail maintained in constant darkness. In DD, all the birds expressed their free-running laying rhythm (period close to 25 h). When the diode is switched on 14 h per 24 h cycle, females showed the same organization as in LD with the same laying time. Thus, a photoperiodic cycle, where light was only perceived through the skull of the female quail, could synchronize its laying rhythm. This device with a LED is an interesting alternative solution to eye-patching or blinding of birds.     

Daily rhythm of oxygen consumption and thermoregulatory responses in some European winter- or summer-acclimatized finches at different ambient temperatures

The oxygen consumption of European finches, the siskin (Carduelis spinus), the brambling (Fringilla montifringilla), the bullfinch (Pyrhulla pyrhulla), the greenfinch (Carduelis chloris) and the hawfinch (Coccothraustes coccothraustes), was recorded continuously while ambient temperature was decreased stepwise from +30 down to-75°C. The oxygen consumption, body temperature (telemetrically), and shivering (integrated pectoral electromyography) of greenfinches were measured simultaneously at ambient temperatures between +30 and-75°C. Maximum heat production, cold limit, lower critical temperature, basal metabolic rate and thermal conductance (of the greenfinch) were determined. The diurnal variation of oxygen consumption of siskins and greenfinches was recorded at thermoneutrality and below the thermoneutral zone in winter- and summer-acclimatized birds. The diurnal variation of body temperature and thermal conductance of greenfinches were also determined. The diurnal variation of heat production was not seasonal or temperature dependent in the siskin and in the greenfinch. Nocturnal reduction of oxygen consumption saved 15–33% energy in the siskin and greenfinch. Body temperature of the greenfinch was lowered by 2.5–3.4°C. The nocturnal reduction of thermal conductance in the greenfinch was 39–48%. The basal metabolic rate was lowest in the largest bird (hawfinch) and highest in the smallest bird (siskin). The values were in the expected range. The heat production capacity of finches in winter was 4.7 times basal metabolic rate in the siskin, 4.2 times in the brambling, 3.5 times in the greenfinch and 2.9 times in the bullfinch and hawfinch. The heat production capacity of the siskin and greenfinch was not significantly lower in summer. The cold limit temperatures (°C) in winter were-61.2 in the siskin,-41.3 in the greenfinch,-37.0 in the bullfinch,-35.7 in the brambling and-28.9 in the hawfinch. The cold limit was 14.3°C higher in summer than in winter in the siskin and 8.7°C in the greenfinch. Thermal insulation of the greenfinch was significantly better in winter than in summer. The shivering of the greenfinch increased linearly when ambient temperature was decreased down to-40°C. Maintenance of shivering was coincident with season. In severe cold integrated pectoral electromyography did not correlate with oxygen consumption as expected. The possible existence of non-shivering thermogenesis in birds is discussed. It is concluded that the acclimatization of European finches is primarily metabolic and only secondly affected by insulation.Abbreviations AAT avian adipose tissue - bm body mass - BMR basal metabolic rate - C _t thermal conductance - EMG electromyogram - HP heat production - HP _max maximum heat production - MR metabolic rate - NST non-shivering thermogenesis - RMR resting metabolic rate - RQ respiratory quotient - T _a ambient temperature - T _b body temperature - T _c colonic temperature - T _1c lower critical temperature - TNZ thermoneutral zone - T _st shivering threshold temperature - V oxygen consumption     

Organizational effects of estrogens on brain vasotocin and sexual behavior in quail

Reproductive behavior is sexually differentiated in quail: The male-typical copulatory behavior is never observed in females even after treatment with high doses of testosterone (T). This sex difference in behavioral responsiveness to T is organized during the embryonic period by the exposure of female embryo to estrogens. We showed recently that the sexually dimorphic medial preoptic nucleus (POM), a structure that plays a key role in the activation of male copulatory behavior, is innervated by a dense steroid-sensitive network of vasotocin-immunoreactive (VT-ir) fibers in male quail. This innervation is almost completely absent in the female POM and is not induced by a chronic treatment with T, suggesting that this neurochemical difference could be organizational in nature. This idea was tested by injecting fertilized quail eggs of both sexes on day 9 of incubation with either estradiol benzoate (EB) (25 μg, a treatment that suppresses the capacity to show copulatory behavior in adulthood) or the aromatase inhibitor R76713 (10 μg, a treatment that makes adult females behaviorally responsive to T), or with the solvents as a control (C). At 3 weeks posthatch, all subjects were gonadectomized and later implanted with Silastic capsules filled with T. Two weeks later, all birds were perfused and brain sections were processed for VT immunocytochemistry. Despite the similarity of the adult endocrine conditions of the subjects (all were gonadectomized and treated with T Silastic implants providing the same plasma level of steroid to all subjects), major qualitative differences were observed in the density of VT-ir structures in the POM of the different groups. Dense immunoreactive structures (fibers and a few cells) were observed in the POM of C males but not females; EB males had completely lost this immunoreactivity (and lost the capacity to display copulatory behavior); and, conversely, R76713 females displayed a male-typical VT-ir system in the nucleus (and also high levels of copulatory behavior). Similar changes in immunoreactivity were seen in the nucleus of the stria terminalis and in the lateral septum (VT-ir fibers only in this case) but not in the magnocellular vasotocinergic system. These neurochemical changes closely parallel the effects of the embryonic treatments on male copulatory behavior. The vasotocinergic system of the POM can therefore be considered an accurate marker of the sexual differentiation of brain circuits mediating this behavior. © 1998 John Wiley & Sons, Inc. J Neurobiol 37: 684–699, 1998     

The kinds of traits involved in male--male competition: a comparison of plumage, behavior, and body size in quail

I compared the role of ornate plumage, behavior, and body sizeduring male—male competition in two species of New Worldquail. Gambel's quail (Callipepla gambelii) is a highly ornateand dichromatic species, whereas scaled quail (C. squamata)is unornamented and monochromatic. During paired contests betweenunfamiliar males, high rates of testosterone-mediated behaviors(tidbitting, calling) and large body size (mass, tarsus, andtail length) corresponded to winners. In the highly ornate Gambel's quail, male head plumes also influenced the outcomeof contests. Plume enhancement made Gambel's quail more likelyto win contests, whereas plume removal made males more likelyto lose. Plume position also reflected male status. Winningmales erected plumes, whereas losers frequently flattened them.Some plumage ornaments, such as belly patches, did not playa primary role during male contests. Unlike static ornaments,head plumes are highly modifiable and likely signal immediateinformation regarding a male's intent, similar to a coverablebadge. Combined, intrasexual selection favored dynamic traits(fast display rates, modifiable ornaments) and static traits(body size) as indicators of male condition or motivation.In scaled quail only, male size was favored both by male—malecompetition and female choice. Accordingly, the degree of sizedimorphism (tarsus length) is greater in scaled than in Gambel'squail. The frequency of overt aggression (chases, pecks, displacement)also differed between species. Gambel's quail were very aggressive,and subordinates often challenged their opponents. In contrast, scaled quail were less aggressive, and subordinates rarely disputedrank. Interspecific comparison indicated differences in themaintenance of male status and possibly in the honesty of signaling.Both appear to be related to differences in social system.     

Timing of nocturnal autumn migratory departures in juvenile European robins (Erithacus rubecula) and endogenous and external factors

Many passerine medium distance nocturnal migrants take off from stopover sites not only at the beginning of the night, but also in the middle and at the end of the night. In this paper, we tested two explanations for this phenomenon: (1) that departure time is governed by fuel stores, and (2) that departure time is influenced by the weather. The relationship of temporal distribution of migratory nocturnal departures with body condition and weather factors was studied in juvenile European robins (Erithacus rubecula) during autumn migration. The study was done on the Courish Spit on the Baltic Sea in 1997–2003 by retrapping 74 ringed birds in high mist nets during nocturnal migratory departure. Departure time was not related to fuel stores at arrival and departure, stopover duration, fuel deposition rate or progress of the season. Nor did the local weather at departure influence departure time. A possible reason was a large variation in the behaviour of the birds. European robins which made 1-day stopovers arrived and departed during better weather conditions than birds that stopped over for longer periods. In the former cohort, a significant model with four predictors explained 55% of variation in departure time. It is assumed that weather at the night of departure and during the previous night influenced the time of take-offs in these birds. In robins which made long stopovers, departure time is probably governed by their individual endogenous circadian rhythms of activity, which are related to the environment in a complex way.     

Seasonal and daily rhythms of body temperature in the European hamster (Cricetus cricetus) under semi-natural conditions

Body temperature of five European hamsters exposed to semi-natural environmental conditions at 47° N in Southern Germany was recorded over a 1.5-year period using intraperitoneal temperature-sensitive radio transmitters. The animals showed pronounced seasonal changes in body weight and reproductive status. Euthermic body temperature changed significantly throughout the year reaching its maximum of 37.9±0.2°C in April and its minimum of 36.1±0.4°C in December. Between November and March the hamsters showed regular bouts of hibernation and a few bouts of shallow torpor. During hibernation body temperature correlated with ambient temperature. Monthly means of body temperature during hibernation were highest in November (7.9±0.8°C) and March (8.2±0.5°C) and lowest in January (4.4±0.7°C). Using periodogram analysis methods, a clear diurnal rhythm of euthermic body temperature could be detected between March and August, whereas no such rhythm could be found during fall and winter. During hibernation bouts, no circadian rhythmicity was evident for body temperature apart from body temperature following ambient temperature with a time lag of 3–5 h. On average, hibernation bouts lasted 104.2±23.8 h with body temperature falling to 6.0±1.7°C. When entering hibernation the animals cooled at a rate of -0.8±0.2°C·h^-1; when arousing from hibernation they warmed at a rate of 9.9±2.4°C·h^-1. Warming rates were significantly lower in November and December than in January and February, and correlated with ambient temperature (r=-0.46, P<0.01) and hibernating body temperature (r=-0.47, P<0.01). Entry into hibrnation occured mostly in the middle of the night (mean time of day 0148 hours ±3.4 h), while spontaneous arousals were widely scattered across day and night. For all animals regression analysis revealed free-running circadian rhythms for the timing of arousal. These results suggest that entry into hibernation is either induced by environmental effects or by a circadian clock with a period of 24 h, whereas arousal from hibernation is controlled by an endogenous rhythm with a period different from 24 h.Abbreviations bw body weight - CET central European time - T _a ambient temperature - T _b body temperature - TTL transistor-transistor logic     

Alterations in Rubisco activity and in stomatal behavior induce a daily rhythm in photosynthesis of aerial leaves in the amphibious-plant Nuphar lutea

Nuphar lutea is an amphibious plant with submerged and aerial foliage, which raises the question how do both leaf types perform photosynthetically in two different environments. We found that the aerial leaves function like terrestrial sun-leaves in that their photosynthetic capability was high and saturated under high irradiance (ca. 1,500 μmol photons m⁻² s⁻¹). We show that stomatal opening and Rubisco activity in these leaves co-limited photosynthesis at saturating irradiance fluctuating in a daily rhythm. In the morning, sunlight stimulated stomatal opening, Rubisco synthesis, and the neutralization of a night-accumulated Rubisco inhibitor. Consequently, the light-saturated quantum efficiency and rate of photosynthesis increased 10-fold by midday. During the afternoon, gradual closure of the stomata and a decrease in Rubisco content reduced the light-saturated photosynthetic rate. However, at limited irradiance, stomatal behavior and Rubisco content had only a marginal effect on the photosynthetic rate, which did not change during the day. In contrast to the aerial leaves, the photosynthesis rate of the submerged leaves, adapted to a shaded environment, was saturated under lower irradiance. The light-saturated quantum efficiency of these leaves was much lower and did not change during the day. Due to their low photosynthetic affinity for CO₂ (35 μM) and inability to utilize other inorganic carbon species, their photosynthetic rate at air-equilibrated water was CO₂-limited. These results reveal differences in the photosynthetic performance of the two types of Nuphar leaves and unravel how photosynthetic daily rhythm in the aerial leaves is controlled.     

The effect of stem diameter on European corn borer behavior and survival: potential consequences for IRM in Bt-corn

The ability of non-crop plants to support complete development of insect pests is an important factor for determining the impact of those plants on resistance management programs for transgenic crops. We assessed the effect of one physical factor, plant stem diameter, on the ability of plants to support full development of the European corn borer (ECB), Ostrinia nubilalis Hübner (Lepidoptera: Crambidae), the target pest of transgenic Bt-corn. In the field, European corn borer larvae were significantly more likely to tunnel and survive in plants with larger stem diameters. Larvae were 40× more likely to survive on corn, the largest plant tested, compared to many of the smaller plants. In the laboratory, larvae were more likely to survive in and less likely to abandon the largest diet-filled artificial stems that varied only in stem diameter. In conditions simulating those that an ECB larvae would encounter upon abandoning a host, larvae survived up to three weeks and were able to locate corn as a new host with a significantly higher frequency than would be expected if they were foraging randomly. These results indicate that the probability of ECB larval survival to maturity on a plant other than corn is relatively low and thus these smaller stemmed non-corn plants may not make a substantial contribution to the pool of susceptible adults. Conversely, since more mature larvae are not as susceptible as neonates, any larvae that partially develop on non-corn plants and subsequently colonize Bt-corn may not be exposed to a lethal dose of the toxin. Since some proportion of the individuals that survive could be partially resistant heterozygotes the presence of non-corn host plants could facilitate the development of resistant ECB populations.