Abstracts (first author)

Talk 

Modeling the relationship between age specific fecundity and lifespan in a cohort of fruit flies

Author(s): Van den Heuvel J, Brakefield PM, Kirkwood TBL, Zwaan BJ, Shanley DP

Summary:

Populations of laboratory animals that are selected for increased lifespan often show correlated negative responses in early fecundity. However in some cases late fecundity, or total lifetime fecundity, is higher in the populations selected for increase lifespan. By some, this has been interpreted as a falsification of the disposable soma theory. According to the Y–model, in which the effects of variation in allocation and acquisition on life histories are studied, an alternative is suggested. A negative relationship between lifespan and reproduction can be viewed as variation in allocation, whereas a positive relationship is the result of variation in acquisition. We have analyzed age specific fecundity and lifespan in a cohort of Drosophila melanogaster flies which were individually housed. Early fecundity related negatively with lifespan, while late fecundity related positively with lifespan in the same cohort. We show that a model which incorporates the ideas of the Y-model, disposable soma theory and a decrease in physiological performance when age increases, can explain how the relationship between fecundity and lifespan changes with age. Furthermore, we modeled different environments in which there is variation in extrinsic mortality rates. In high mortality environments there was selection for high early fecundity, low late fecundity and low lifespans, whereas the opposite was true for low mortality environments. Our laboratory population of D. melanogaster was founded from a combination of flies from different areas in Europe and therefore is heterogeneous in genotype. We conclude that the differences in life history strategies found in one cohort of laboratory flies are the result of a mosaic of selection on the relationship between fecundity and lifespan over age.


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Abstracts (coauthor)

Summary:

Dietary restriction (DR), a reduction in food intake without malnutrition, is a well-studied topic in ageing research. However, knowledge about mechanisms mediating this response is scarce. We know the Insulin-IGF Signalling (IIS) pathway is involved in ageing in many organisms. In Drosophila, insulin-like peptides (DILPs), upstream components of IIS, respond to different food conditions and a dilp2-3,5 knockout extends lifespan. This suggests that dilps can have a role in mediating the DR response. We investigated the role of dilps in nutrient-altered ageing by determining lifespan, fecundity and brain-dilp expression of the long-lived dilp2-3,5 knockout mutant (d235∆)and its genetic control (wDah) on a range of food types that differed in sugar and yeast concentration. We showed that d235∆ flies had an increased lifespan and decreased reproduction on all food types compared to wDah flies. There was still a nutrient-dependent lifespan and reproduction response for d235∆ flies, but the effect of the highest sugar and yeast concentrations was reduced for both lifespan and fecundity. For gene expression, in wDah flies dilp2 and -3 expression increased on high yeast and lower sugar concentrations, dilp5 expression increased on high yeast concentrations and dilp6 expression did not change on different sugar or yeast concentrations. Interestingly, in d235∆ flies dilp6 expression increased on high yeast concentrations. This data shows that dilp2, 3 and 5 may have a role but are not the key in mediating the DR response. We hypothesize that dilp6 expression may take over expression of dilp2, -3 and -5 in the d235∆ flies, but not sufficient to maintain the same lifespan and reproduction on every food type.

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Address

XIV Congress of the European Society for Evolutionary Biology

Organization Team
Department of Animal Biology (DBA)
Faculty of Sciences of the University of Lisbon
P-1749-016 Lisbon
Portugal

Website

Computational Biology & Population Genomics Group 
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