Cooperation, conflict, and the coordination of care in the long-tailed tit, Aegithalos caudatus

Parental care is costly to carers, so when multiple carers raise the same offspring, each is selected to maximise their benefit-to-cost ratio at the expense of others, causing conflict between carers over relative investment. Coordinated provisioning is hypothesised to resolve this conflict and to mitigate the costs of care. In this thesis, I investigated whether, how, and why pairs and cooperative groups of long-tailed tits, Aegithalos caudatus, performed two forms of coordinated care, alternation (i.e. taking turns) and synchrony (i.e. feeding together). In chapter 2, I used a long-term database of provisioning watches to determine whether carers coordinate their provisioning. Carers alternated and synchronised more than expected by chance, and helpers were more synchronous than breeders, although their level of coordination was not influenced by relatedness to the parents. In chapter 3, I investigated the behavioural mechanisms underlying coordination, finding that alternation was facilitated by carers actively delaying feeding near the nest if it was not their turn to feed. Synchronised feeds were facilitated by synchronous arrivals near the nest, typically led by breeding females, indicating collective foraging. In chapters 4 and 5, I conducted an experiment and analysed long-term data to test several hypotheses for the adaptive function of coordination. A high level of alternation was associated with higher provisioning rates and greater breeding productivity, as predicted by the hypothesis that conditional cooperation mitigates conflict among carers. Synchrony of nest visits across the nestling period was associated with a reduced brood predation risk in the long-term dataset, although the experimental manipulation of perceived predation threat did not cause a temporary increase in synchrony. I conclude that coordinated care in long-tailed tits is adaptive; alternated provisioning functions to resolve conflict between carers, thereby preventing exploitation, and synchronous provisioning reduces the chance that a brood’s location is advertised to predators

Adaptive evolution of synchronous egg-hatching in compensation for the loss of parental care.

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

Experimental evolution of a more restrained clutch size when filial cannibalism is prevented in burying beetles Nicrophorus vespilloides.

Funder: FP7 Ideas: European Research Council; Id: http://dx.doi.org/10.13039/100011199; Grant(s): 310785The overproduction of offspring is commonly associated with high hatching failure and a mechanism for dispensing with surplus young. We used experimental evolution of burying beetle populations Nicrophorus vespilloides to determine causality in these correlations. We asked does eliminating the mechanism for killing "spare" offspring cause the evolution of a more restrained clutch size and consequently select for reduced hatching failure? N. vespilloides typically overproduces eggs but kills 1st instar larvae through partial filial cannibalism during brood care. We established replicate evolving populations that either could practice filial cannibalism (Full Care) or could not, by removing parents before their young hatched (No Care). After 20+ generations of experimental evolution, we measured clutch size and hatching success. We found that No Care females produced fewer eggs than Full Care females when allowed to breed on a small corpse, a finding not explained by differences in female quality. On larger corpses, females from both populations laid similar numbers of eggs. Furthermore, hatching success was greater in the No Care populations on small corpses. Our results suggest that the adaptive overproduction of offspring depends on a mechanism for eliminating surplus young and that killing offspring, in turn, relaxes selection against hatching failure

Coordination of care by breeders and helpers in the cooperatively breeding long-tailed tit

Abstract In species with biparental and cooperative brood care, multiple carers cooperate by contributing costly investments to raise a shared brood. However, shared benefits and individual costs also give rise to conflict among carers conflict among carers over investment. Coordination of provisioning visits has been hypothesized to facilitate the resolution of this conflict, preventing exploitation, and ensuring collective investment in the shared brood. We used a 26-year study of long-tailed tits, Aegithalos caudatus, a facultative cooperative breeder, to investigate whether care by parents and helpers is coordinated, whether there are consistent differences in coordination between individuals and reproductive roles, and whether coordination varies with helper relatedness to breeders. Coordination takes the form of turn-taking (alternation) or feeding within a short time interval of another carer (synchrony), and both behaviors were observed to occur more than expected by chance, that is, “active” coordination. First, we found that active alternation decreased with group size, whereas active synchrony occurred at all group sizes. Second, we show that alternation was repeatable between observations at the same nest, whereas synchrony was repeatable between observations of the same individual. Active synchrony varied with reproductive status, with helpers synchronizing visits more than breeders, although active alternation did not vary with reproductive status. Finally, we found no significant effect of relatedness on either alternation or synchrony exhibited by helpers. In conclusion, we demonstrate active coordination of provisioning by carers and conclude that coordination is a socially plastic behavior depending on reproductive status and the number of carers raising the brood.</jats:p

Biased pollen transfer by bumblebees favors the paternity of virus-infected plants in cross-pollination.

We used a green fluorescent protein marker gene for paternity analysis to determine if virus infection affected male reproductive success of tomato in bumblebee-mediated cross-pollination under glasshouse conditions. We found that bumblebees that visited flowers of infected plants showed a strong preference to subsequently visit flowers of non-infected plants. The behavior of the bumblebees to move toward non-infected plants after pollinating virus-infected plants appears to explain the paternity data, which demonstrate a statistically significant ∼10-fold bias for fertilization of non-infected plants with pollen from infected parents. Thus, in the presence of bumblebee pollinators, CMV-infected plants exhibit enhanced male reproductive success

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Not AvailableSoft tissue from cultured farm fresh oysters (Crassostrea madrasensis) was subjected to two standard enzymatic peptide extraction procedures using pepsin and papain. The crude extracts obtained were partially purified by column chromatography and were freeze-dried. The hydrolysates obtained were compared with respect to their degree of hydrolysis (DH), antioxidant potential (AP) and total phenolic content (TPC). The hydrolysate showing better antioxidant property was further subjected to purification by high performance liquid chromatography and characterized by LC-MS/MS. Papain-digested oyster protein (OPHpap) hydrolysate showed higher DH, AP and TPC. OPHpap was further subjected to ultrafiltration and fractionated into 3 sizes namely, above 10, 3–10 and 1–3 kDa according to the molecular size. Antioxidant capacity of\3 kDa fraction OPHpap-3 evaluated by DPPH free radical scavenging assay, metal chelating activity, linoleic acid autoxidation assay showed maximum effectiveness. Of the seven fractions collected by purification of OPH-pap-3 on semi-preparative RP-HPLC, fraction 7 that showed the highest antioxidant activity was further characterized by LC-ESI-MS/MS and its sequence determined. An antioxidant peptide molecule with thirteen amino acids was identified in oyster protein hydrolysate obtained by papain digestion that may find application as a nutraceutical or may be utilized in food industry for prevention of rancidity in foods.Not Availabl

Functions and dysfunctions of nitric oxide in brain

Nitric oxide (NO) works as a retrograde neurotransmitter in synapses, allows the brain blood flow and also has important roles in intracellular signaling in neurons from the regulation of the neuronal metabolic status to the dendritic spine growth. Moreover NO is able to perform post-translational modifications in proteins by the S-nitrosylation of the thiol amino acids, which is a physiological mechanism to regulate protein function. On the other hand, during aging and pathological processes the behavior of NO can turn harmful when reacts with superoxide anion to form peroxynitrite. This gaseous compound can diffuse easily throughout the neuronal membranes damaging lipid, proteins and nucleic acids. In the case of proteins, peroxynitrite reacts mostly with the phenolic ring of the tyrosines forming nitro-tyrosines that affects dramatically to the physiological functions of the proteins. Protein nitrotyrosination is an irreversible process that also yields to the accumulation of the modified proteins contributing to the onset and progression of neurodegenerative processes such as Alzheimer's disease or Parkinson's disease.This work was supported by the Spanish Ministry of Economy and Business through the grant Plan Estatal SAF2017-83372-R (FEDER funds/UE) and MDM-2014-0370 through the “María de Maeztu” Programme for Units of Excellence in R&D to “Departament de Ciències Experimentals i de la Salut”