Direct and correlated responses to selection for longevity in Drosophila buzzatii

Genetic, Environmental, and Stochastic Components of Lifespan Variability: The Drosophila Paradigm

Lifespan is a complex quantitative trait involving genetic and non-genetic factors as well as the peculiarities of ontogenesis. As with all quantitative traits, lifespan shows considerable variation within populations and between individuals. Drosophila, a favourite object of geneticists, has greatly advanced our understanding of how different forms of variability affect lifespan. This review considers the role of heritable genetic variability, phenotypic plasticity and stochastic variability in controlling lifespan in Drosophila melanogaster. We discuss the major historical milestones in the development of the genetic approach to study lifespan, the breeding of long-lived lines, advances in lifespan QTL mapping, the environmental factors that have the greatest influence on lifespan in laboratory maintained flies, and the mechanisms, by which individual development affects longevity. The interplay between approaches to study ageing and lifespan limitation will also be discussed. Particular attention will be paid to the interaction of different types of variability in the control of lifespan.

Food deprivation exposes sex‐specific trade‐offs between stress tolerance and life span in the copepod Tigriopus californicus

Long life is standardly assumed to be associated with high stress tolerance. Previous work shows that the copepod Tigriopus californicus breaks this rule, with longer life span under benign conditions found in males, the sex with lower stress tolerance. Here, we extended this previous work, raising animals from the same families in food‐replete conditions until adulthood and then transferring them to food‐limited conditions until all animals perished. As in previous work, survivorship under food‐replete conditions favored males. However, under food deprivation life span strongly favored females in all crosses. Compared to benign conditions, average life span under nutritional stress was reduced by 47% in males but only 32% in females. Further, the sex‐specific mitonuclear effects previously found under benign conditions were erased under food limited conditions. Results thus demonstrate that sex‐specific life span, including mitonuclear interactions, are highly dependent on nutritional environment.

Life-history traits and physiological limits of the alpine fly Drosophila nigrosparsa (Diptera: Drosophilidae): A comparative study

Interspecific variation in life-history traits and physiological limits can be linked to the environmental conditions species experience, including climatic conditions. As alpine environments are particularly vulnerable under climate change, we focus on the montane-alpine fly Drosophila nigrosparsa. Here, we characterized some of its life-history traits and physiological limits and compared these with those of other drosophilids, namely Drosophila hydei, Drosophila melanogaster, and Drosophila obscura. We assayed oviposition rate, longevity, productivity, development time, larval competitiveness, starvation resistance, and heat and cold tolerance. Compared with the other species assayed, D. nigrosparsa is less fecund, relatively long-living, starvation susceptible, cold adapted, and surprisingly well heat adapted. These life-history characteristics provide insights into invertebrate adaptations to alpine conditions which may evolve under ongoing climate change.

Patterns of longevity and fecundity at two temperatures in a set of heat-selected recombinant inbred lines of Drosophila melanogaster

Quantitative trait loci (QTL) were mapped for longevity and fecundity at two temperatures, 20 and 30 °C, in two sets of recombinant inbred lines (RIL) highly differing in thermotolerance. Early fecundity (EF) and longevity showed a negative association between temperatures. For instance, longevity was higher and fecundity was lower in the RIL panel showing higher life span at 30 °C. One X-linked QTL (7B3-12E) co-localized for longevity and EF at 20 °C, with one QTL allele showing a positive additive effect on longevity and a negative effect on EF. The across-RIL genetic correlation between longevity and EF was not significant within each temperature, and most QTL that affect life span have no effect on EF at each temperature. EF and longevity can mostly be genetically uncoupled in the thermotolerance-divergent RIL within each temperature as opposed to between temperatures. QTL were mostly temperature specific, although some trait-specific QTL showed possible antagonistic effects between temperatures.

Phenotypic trait changes in laboratory--reared colonies of the maize herbivore, Diabrotica virgifera virgifera

The North American and European maize pest Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae) was used to assess whether conditions of the natal field, subsequent laboratory rearing, or genetic population origin affect phenotypic traits of fitness, activity, or morphometrics. Standardized laboratory bioassays with large sample sizes revealed that none of the 16 tested traits, except crawling behaviours, appeared consistently stable across all seven tested colonies. Environmental conditions in the natal field of the F 0 generation affected trait averages of the subsequently reared F 1 generation in laboratory in ca. 47% of cases, and trait variability in 67% of cases. This was apparent for fitness and morphometrics, but less obvious for activity traits. Early generation laboratory rearing affected trait averages in ca. 56% of cases: morphometrics changed; fecundity and egg survival increased from F 1 to F 2. Trait variability increased or decreased in 38% of cases. Laboratory rearing for over more than 190 generations affected the trait averages in 60% of cases, reflected by decreases in flight activity and increases in body size, weight, and fecundity to some extent. It had little effect on trait variability, especially so for morphometric variability. The genetic population origin affected average levels of 55% and variability of 63% of phenotypic traits. A comparison among D. v. virgifera studies might be difficult if they use different populations or laboratory colonies. It is advised to consider possible effects of original field conditions, laboratory rearing, and population genetics when planning comparative studies targeting fitness, activity, or morphometric questions regarding Diabrotica species.