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Nutrition and reproductive strategies: the influence of dietary antioxidants on telomere dynamics and life history plasticity in birds

Final Report Summary - EVOTELOX (Nutrition and reproductive strategies: the influence of dietary antioxidants on telomere dynamics and life history plasticity in birds)


Objectives of the project and methodology

The project ‘EVOTELOX’ had two clear and well defined objectives. First, I aimed to assess the extent to which antioxidant and micronutrient availability in the diet affects telomere dynamics and oxidative status during early life (first phase of the project) and secondly, whether nutritional conditions and telomere dynamics during early life affect the speed of sexual maturation and reproductive investment during adulthood (second phase). To that end, firstly, I performed an experiment where I modified the availability of dietary micronutrients (e.g. antioxidants and essential minerals) during early development and sexual maturation of zebra finches (Taeniopygia guttata), and I measured and blood sampled these birds periodically. I used blood samples to determine the effects of the experimental treatment on oxidative status (i.e. non-enzymatic and enzymatic antioxidant levels and oxidative damage on lipids) and telomere dynamics (telomere length and loss) with age, and I also examined theses in relation to growth patterns of these birds. At the same time, I also assessed the development of secondary sexual characters (i.e. adult plumage, bill colour and intensity) of these birds until they were fully adults. I combined these data together with the results of a second experiment to understand how early life antioxidant and micronutrient during development influenced the speed of sexual maturation and the investment in reproduction. During the second experiment (second phase of the project), I allowed the birds that were reared on different micronutrient regimens to breed with a standard partner. This second experiment allowed me to assess different reproductive traits of the experimental birds (i.e. clutch size, brood size, latency to start reproduction, etc.) as well as key life history traits (i.e. growth) in the offspring.

Main results of the project

In brief, the main findings of this project can be summarised as follow (a detailed description of the main results is provided in the Supplemental Material):

-1- The adult antioxidant defence system is influenced by the availability of dietary micronutrients received during early and later development and such effects seem to fit with an ‘Environmental-matching’ model; during the period of late development only those birds that continued with the same dietary treatment as during early development showed a significant increase in their level of antioxidant defences.

-2- The availability of diet micronutrients during sexual maturation affected the rate of telomere loss and final telomere length but such effects differed between sexes; females reared on a high micronutrient diet had longer telomeres and experienced lower telomere loss than males. Irrespective of the sex, birds in the low micronutrient diet experienced higher rate of telomere loss and had shorter telomeres. Moreover, the family of origin had a strong effect on both telomere length and loss suggesting a genetic influence (heritability) on both traits.

-3-The speed of development and intensity of antioxidant-demanding secondary sexual characters is influenced by the availability of diet micronutrients; in agreement with the findings for antioxidant defences, those birds that maintained the same diet during both the growth period and sexual maturation had a faster development of adult bill colour. Also, during the period of sexual maturation, those birds fed with a low micronutrient diet had a redder bill colour (bill hue) suggesting a greater investment in sexual maturation. Importantly, our preliminary analyses revealed a marginally significant positive trend between the rate of telomere loss and the investment in sexual maturation (bill hue) during this period.

-4- Early and late dietary conditions experienced by the mother affect the investment in reproduction and offspring growth trajectories; although these data are still being analysed, my preliminary analyses show that mothers reared on a high micronutrient diet during both early development and the period of sexual maturation seem to invest less in reproduction (e.g. fewer breeding attempts) than any other experimental group. However, when reproducing, these females performed better (higher fertility rates, hatching success and clutch size) and had offspring with higher growth rates.

In terms of publication, I am just finishing writing the first two manuscripts about the effect of nutrition on oxidative status and telomere loss (results 1 and 2) which I plan to submit for publication in the next few months to the Journal of Experimental Biology and to Biology Letters. Additionally, during these two years I have published four different manuscripts in top journals of my field of research - three of them as co-author (Journal of Evolutionary Biology 2013, 26, 1341-1352; Animal Behaviour 2013, 85, 1359-1366; Proceeding of the Royal Society of London 2014, 281, 20133151) and one as the main author (Hormones & Behaviour 2013, 64, 19-25) (see supplementary information for a summary of main findings). Moreover, over the last year and complementary to the planned tasks, I assessed different aspects of personality of my birds as well as their reproductive behaviour. These two complementary experiments have allowed me to test the effect that nutrition can exert in the development of adult personality traits and reproductive strategies. As a result of these studies, I have already submitted a new manuscript (to the journal Animal Behaviour; under review) and I am currently preparing a second manuscript on this topic which I plan to submit for publication in the next months. I have also successfully achieved the other planned tasks related to my own development: acquiring new skills, attendance at conferences and dissemination of results. Thus, for instance, most of the results obtained during this two years have also been presented in national and international congresses (i.e. The International Congress of Animal Behaviour, Newcastle, 2013; the Mini-Symposium on Oxidative Stress founded by the Rank Prize Funds, Grasmere 2014; the Scottish Ecological Ageing Research Meeting, Durham 2012; the Scottish Conference on Animal Behaviour, Glasgow 2013, Edinburgh 2014; The international conference of the Society for Experimental Biology, Manchester 2014).
Finally, as I mentioned before, some of the data sets from the second phase of the project are still being analysed which means that the results and potential publications from this project will increase in the next few months. A part of the publication record and dissemination of the results, an important personal achievement during the duration of the project has been the acquirement of a new 2-year post-doctoral fellowship funded by AXA and to be held at the University of Glasgow. This new research project has been designed on the basis of the Marie Curie project and therefore, it will allow me to continue my work on the effects of nutrition on telomere dynamics, senescence and life-history strategies. In summary, I think this project has been very successful and the results are very promising. Given the increasing general interest in understanding the role of nutritional components on human health and diseases around the world and particularly within the EU, I really think that the outcome of this project will be of great interest not only for other researchers working on ageing but also for the general public and police makers.