Maternal Vibration: An Important Cue for Embryo Hatching in a Subsocial Shield Bug (original) (raw)
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Adaptive evolution of synchronous egg-hatching in compensation for the loss of parental care
Proceedings of the Royal Society B: Biological Sciences
Interactions among siblings are finely balanced between rivalry and cooperation, but the factors that tip the balance towards cooperation are incompletely understood. Previous observations of insect species suggest that (i) sibling cooperation is more likely when siblings hatch at the same time, and (ii) this is more common when parents provide little to no care. In this paper, we tested these ideas experimentally with the burying beetle, Nicrophorus vespilloides. Burying beetles convert the body of a small dead vertebrate into an edible nest for their larvae, and provision and guard their young after hatching. In our first experiment, we simulated synchronous or asynchronous hatching by adding larvae at different intervals to the carrion-breeding resource. We found that 'synchronously' hatched broods survived better than 'asynchronously' hatched broods, probably because 'synchronous hatching' generated larger teams of larvae, that together worked more effectively to penetrate the carrion nest and feed upon it. In our second experiment, we measured the synchronicity of hatching in experimental populations that had evolved for 22 generations without any post-hatching care, and control populations that had evolved in parallel with post-hatching care. We found that larvae were more likely to hatch earlier, and at the same time as their broodmates, in the experimental populations that evolved without post-hatching care. We suggest that synchronous hatching enables offspring to help each other when parents are not present to provide care. However, we also suggest that greater levels of cooperation among siblings cannot compensate fully for the loss of parental care.
Functional Ecology, 2006
1. Asynchronous hatching has been studied extensively in altricial birds that feed their offspring, but this phenomenon is also known to occur in insects where parents provide food for their offspring. 2. We examined the proximate mechanisms underlying asynchronous hatching in the burying beetle Nicrophorus vespilloides , an insect species in which parents feed their offspring. 3. Mean hatching spread was 30 h. As expected if egg-laying was the major proximate mechanism underlying variation in hatching patterns, the duration of the egg-laying period had a highly significant and positive effect on hatching spread. The duration of the egg-laying period was unrelated to clutch size. 4. Hatching spread was slightly but significantly reduced compared with the duration of the egg-laying period, and the last eggs laid by females developed slightly but significantly faster than the first eggs. There was no significant difference in the size of the larvae that hatched from the first and last eggs laid by females. 5. We discuss the value of N. vespilloides and other insects where parents provide food for their offspring as alternative models to birds for the evolution of asynchronous hatching.
Environmentally Cued Hatching in Reptiles
Integrative and Comparative Biology, 2011
Synopsis Evidence is accumulating for the widespread occurrence of environmentally cued hatching (ECH) in animals, but its diversity and distribution across taxa are unknown. Herein I review three types of ECH in reptiles: early hatching, delayed hatching, and synchronous hatching. ECH is currently known from 43 species, including turtles, crocodilians, lizards, snakes, tuatara, and possibly worm lizards. Early hatching caused by physical disturbance (e.g., vibrations) is the most commonly reported ECH across all groups; although it apparently serves an antipredator function in some species, its adaptive value is unknown in most. Delayed hatching, characterized by metabolic depression or embryonic aestivation, and sometimes followed by a hypoxic cue (flooding), occurs in some turtles and possibly in monitor lizards and crocodilians; in some of these species delayed hatching serves to defer hatching from the dry season until the more favorable conditions of the wet season. Synchronous hatching, whereby sibling eggs hatch synchronously despite vertical thermal gradients in the nest, occurs in some turtles and crocodilians. Although vibrations and vocalizations in hatching-competent embryos can stimulate synchronous hatching, cues promoting developmentally less advanced embryos to catch up with more advanced embryos have not been confirmed. Synchronous hatching may serve to dilute predation risk by promoting synchronous emergence or reduce the period in which smells associated with hatching can attract predators to unhatched eggs. Within species, advancing our understanding of ECH requires three types of studies: (1) experiments identifying hatching cues and the plastic hatching period, (2) experiments disentangling hypotheses about multiple hatching cues, and (3) investigations into the environmental context in which ECH might evolve in different species (major predators or abiotic influences on the egg, embryo, and hatchling). Among species and groups, surveys for ECH are required to understand its evolutionary history in reptiles. The probability of ECH occurring is likely influenced by a species's life history, ecology, behavior, and interrelationships with other species (e.g., sizes of predator and prey). More broadly, the discovery of embryo-embryo communication as a mechanism for synchronous hatching in crocodilians and turtles indicates that the social behavior of (nonavian) reptiles has been underestimated.
Embryonic calls as care-soliciting signals in budgerigars Melopsittacus undulatuss
Embryonic calls occur I -3d before hatching among precocial and sonic altricial birds. In pl-ecocial species, calls may synchronize hatching among siblings or, in semi-precocial species. elicit parental attention to, and often thermoregulation of, the hatching egg. Much less is known about the functional significance of calls ni fully altricial species. In this 5lUdy. naturalistic observations and laboratoiy experiments were used to document factors affecting calling and the parental responses to calls in one altricial species. the budgerigar Mehpsittucus undulufus. Budgerigar chicks hatch asynchronously and vocalize 2 4 4 8 h before hatching. Embryonic calling ratcs increase at higher egg temperatures, and also as embryos near hatching. Parents easily locate a calling egg in their clutch, even among a large brood of much older, vocalizing nestlings. Furthermore, they actively assist in the last stages of hatching by helping to break the shell along the crack in the egg. Both observational and experimental evidence suggests that embryonic vocalizations are distinctive signals that increase parental attention and care, and may stimulate hatching assistance to a calling egg.
Maternal compensation for hatching asynchrony in the collared flycatcher Ficedula albicollis
Journal of Avian Biology, 2005
14. Paper 5. Food allocation in collared flycatcher (Ficedula albicollis) broods: Do rules change with the age of nestlings? 77 15. Summary / Összefoglalás 91 Howe HF (1976) Egg size, hatching asynchrony, sex, and brood reduction in the Common Grackle. Ecology 57:1195-1207 Hussell DJT (1972) Factors affecting clutch size in Arctic passerines. Ecol Monogr 42:317-364 Hussell DJT (1990) Regulation of food provisioning in broods of altricial birds. In: Acta XX. Congressus Internationalis Ornithologici, pp 946-960 Johnson LS, Wimmers LE, Campbell S, Hamilton L (2003) Growth rate, size, and sex ratio of last-laid, last-hatched offspring in the tree swallow Tachycineta bicolor. J Avian Biol 34:35-43 Kempenaers B, Verheyen GR, van den Broeck M, Burke T, van Broeckhoven C, Dhondt AA (1992) Extra-pair paternity results from female preference for high-quality males in the blue tit. Nature 357:494-496 Kilner R (1995) When do Canary parents respond to nestling signals of need? Proc R Soc Lond B 260:343-348
Tests of Three Hypotheses of Hatching Asynchrony in the Common Tern
The Auk, 1990
We examined three hypotheses concerning hatching asynchrony in the Common Tern (Sterna hirundo). Survival of third-hatching "C-chicks" was significantly lower than that of "A-" and "B-chicks" in broods of three. In 2 yr when conditions did not appear favorable, survival was significantly higher in manipulated broods in which chicks hatched synchronously (73%) than in nonmanipulated broods (56%). Chicks in synchronous broods grew significantly faster than C-chicks and at a rate similar to A-and B-chicks. These results were inconsistent with the brood-reduction hypothesis, which predicts that hatching asynchrony will maximize brood success under conditions of food limitation. Chicks hatching from C-eggs grew significantly faster and survived at nonsignificantly higher rates when an older sibling was removed experimentally. These results were consistent with the hypothesis that C-chicks serve as insurance against loss of an older sibling. All three siblings, however, survived in 26% of nonmanipulated broods, which indicates that the sole function of the C-chick was not insurance. Predation on tern eggs was common and was correlated with numbers of migrating Ruddy Turnstones (Arenaria interpres). The percentage of time adults incubated was lower when only one egg had been laid than when two or three eggs were laid, and egg predation was most frequent during this initial stage. Although hatching asynchrony did not maximize chick survival, incubation before laying is completed may maximize overall nest success by protecting eggs from predators.
A Big Bang or small bangs? Effects of biotic environment on hatching
Journal of Limnology, 2008
The beginning and end of diapause are two important transition points in cladoceran life history. The influence of environmental variables on the dynamics of these processes still deserves attention, especially as concerns the role of biotic factors. In this paper we focus on emergence from diapause, testing (1) whether ephippia of Daphnia obtusa Kurz can assess the presence in the water of typical planktivorous fish or ostracods, and (2) whether such an assessment results in changes in hatching strategy. Total number of hatchlings from D. obtusa ephippial eggs did not differ between the control and the treatments in which the presence of fish or ostracods could be detected (ANOVA, P = 0.884). However, hatching dynamics were different: most of the eggs hatched synchronously at day 4 (83.3% of the total hatchlings number) in the control, while only a low proportion of eggs hatched on day 4 in the fish (38.3%), and ostracod treatments (24.0% of the total). Mean hatching time was longer, and variability larger, in the treatments than in the control; differences resulted statistically significant (ANOVA, P = 0.005). With respect to the control, representing a simple microcosm controlled by abiotic variables only, the treatments may be regarded as relatively complex environments, in which Daphnia is also exposed to biotic cues. Under these more complex conditions, the same number of hatchlings is obtained through different hatching dynamics. In the treatments, the first hatchlings appeared later and the hatching rate was more variable than in the control. These observations confirm previously observed patterns from laboratory experiments which tested the effect of competition and fluctuating environmental conditions (light:dark, temperature regimes) on D. obtusa reproductive and demographic parameters. They are also in agreement with recently obtained evidence concerning the importance of biotic cues for hatching of ephippial eggs. Overall, the evidence suggests that Daphnia can detect infochemicals during dormancy. Specifically, we propose that the presence in the water medium of potential predators and competitors results in a short-term hatching asynchrony of ephippial eggs.
INCUBATION TEMPERATURE AND YOLK STEROIDS REGULATE HATCHING SYNCHRONY IN Calotes versicolor (DAUD
The chronology of hatching behavior, hatching success and the significance of maternal yolk steroids (estradiol and testosterone) in hatching synchrony were studied in the lizard Calotes versicolor at male-producing (25.5 ± 0.5 and 34 ± 0.5°C), female-producing (23.5 ± 0.5 and 31.5 ± 0.5°C) and at high (35°C) temperatures. The results reveal that in a given clutch, the embryo that has utilized most of its yolk initiates the pipping behavior first. Hatching success as well as incubation period decreases with increase in incubation temperature and the temperatures from 23.5 ± 0.5°C to 31.5 ± 0.5°C are recorded as optimum viable range for the development and successful hatching of C. versicolor eggs. Hatching is highly synchronous in C. versicolor irrespective of incubating temperature, sex and clutch-to-clutch differences. Significance of maternal steroids in hatching pattern was studied at both male and female-producing temperatures. High interclutch variance, but low intraclutch variance in estradiol and testosterone concentrations found at oviposition as well as at hatching suggest their possible role in the synchronization of hatching by exhibiting similar magnitude of steroid profile within a clutch. It is observed that there is no sex based hatching synchrony in this species. The study indicates that temperature and steroids act synergistically and might play a role in synchronization of hatching in C. versicolor.