Biology subjects

Temura, C.

Publications and source records attributed to Temura, C..

4 recordsLinked to original sources

bioRxiv2026

Revisiting the evolution of population stability due to selection for rapid development and early reproduction in Drosophila: the role of generation length

The ubiquity of stable populations in nature generated considerable interest in how population stability might evolve, especially after the realization that higher per capita population growth rates typically yield unstable dynamics. Yet, most empirical and theoretical treatments implicitly assume that population dynamics and stability are invariant to generation length, an assumption that remains largely untested. Theory suggested that population stability could evolve as a correlated response to life-history evolution, which was first experimentally demonstrated using D. melanogaster populations selected for rapid development and early reproduction (FEJs). Constancy stability of FEJs evolved to be higher than their ancestral controls (JBs), likely due to correlated reductions in fecundity and pre-adult survivorship. However, that study assessed stability on a 21-day generation length (matching the JBs), resulting in a considerable mismatch with the generation length of FEJs (10 days). This raises a broader question of whether the observed differences in stability reflect evolved life-history changes or are an artifact of the generation length at which the populations were assayed. To address this, we assessed the stability of FEJs, JBs, and relaxed-selection populations derived from the FEJs (CRFs and FRFs) across two generation lengths (12 and 18 days), tracking 320 small populations for 27 generations. Contrary to the earlier findings based on a 21-day generation length study, FEJs did not differ in constancy from JBs when assayed at a shorter generation length. Thus, even a modest difference in life-cycle length can significantly influence population stability, thereby underscoring the need to account for generation length when comparing stability across populations. Interestingly, constancy and persistence stability of selection regimes evolved in opposite directions, highlighting the need to assess stability along multiple axes. We discuss these results using an empirical framework, emphasizing its utility over simple population growth models for a richer understanding of population dynamics and stability.

ecology↗

bioRxiv2025

Fitness effects of adult crowding in Drosophila: more than just overall density

Density-dependent selection has been widely studied in D. melanogaster in the context of larval crowding, revealing its impact on several life-history traits. However, the effects of adult crowding in Drosophila have not been studied in similar detail. Earlier studies on adult crowding have primarily used large flies (reared at low larval density). These gave rise to the notion that adult crowding negatively affects key fitness components such as mortality and fecundity. Earlier work from our lab showed that body size significantly alters how flies respond to a relatively short period of adult crowding. Large flies show increased mortality and decreased fecundity with increased adult density. In contrast, small flies (reared at high larval density) tolerate adult crowding better, showing increased fecundity with increased adult density. Here, we extend this line of work by investigating how air volume in a culture vial can influence the effects of adult crowding. We manipulated air volume by altering the vial diameter (thereby also the food surface area), or the height of the air column. Flies of different body sizes were generated by rearing them at low or high larval densities. We find that the surface area of food available to the adults plays a greater role in shaping the outcome of adult crowding than the height of the air column. Large flies displayed context-dependent responses to adult crowding that were driven by the surface area of food provided. Small flies consistently responded positively to adult crowding in all conditions, with low mortality and increased fecundity at high adult density. Our findings highlight the importance of considering the body size, absolute density and the food surface area available to the flies and their nuanced interactions while exploring the effects of adult crowding, and thus paves the way for a detailed examination of other factors that impact adult crowding in addition to just the overall density.

ecology↗

bioRxiv2025

Bigger is not always better: size-dependent fitness effects of adult crowding in Drosophila melanogaster

Density-dependent selection is an important factor shaping the evolution of life histories. In holometabolous insects, crowding in the larval and adult stages can have very different effects on key fitness components. While the nuanced effects of density-dependent selection through larval crowding in Drosophila melanogaster have been extensively studied for various life history traits, very few studies have investigated the effects of adult crowding in Drosophila. Moreover, these few studies were mostly conducted on large flies, derived from low larval density cultures, and typically treated the overall density of flies per culture container as an index of the strength of adult crowding. We hypothesized that the size of the adults should shape the impact of adult crowding, with small individuals experiencing less stress than large individuals when crowded. Consequently, the adverse fitness effects usually associated with adult crowding may not be observed for small individuals. We tested this hypothesis by subjecting flies of different sizes - regular-sized flies, and small flies derived via larval crowding or selection for rapid development to adulthood - to an episode of adult crowding and examining their mortality and fecundity. Thus, we explored the interactive effects between larval and adult crowding on key fitness components. Small body size enabled flies to handle adult crowding better, with significantly lower mortality under crowded conditions when compared to flies of large body size. Moreover, small flies showed a consistent pattern of increased fecundity upon adult crowding. This positive impact on fecundity was not observed when larger flies were crowded. It is clear from our study that the effects of adult crowding can be very nuanced and body size-specific, even to the extent of having a net beneficial effect on fitness components, contrary to previous belief.

ecology↗

bioRxiv2023

The evolution of competitive effectiveness and tolerance in populations of Drosophila melanogaster adapted to chronic larval crowding at varying combinations of egg number and food volume

The theory of density-dependent selection posits that genotypic fitness can vary depending on the population density. Several long-term selection experiments on outbred populations of Drosophila adapted to chronically high larval densities have shown that the most common evolutionary response of such rearing is an increase in larval competitive ability. Some authors have proposed that a better understanding of the evolution of competitive ability can be achieved by its partitioning into effectiveness and tolerance components. Effectiveness is the amount of competitive inhibition imposed by a competitor on another, whereas tolerance is the degree to which a competitor can withstand inhibition. In this study, we have explored the evolution of effectiveness and tolerance components of competitive ability using three sets of outbred populations of D. melanogaster adapted to chronic larval crowding at different respective combinations of egg number, food volume and container dimensions. Effectiveness and tolerance were found to be dependent on the particular selection regime, the starting food amount and the trait used as the outcome of competition. Eclosion, dry biomass and dry weight per fly distributions over time indicated that competitive ability can also express itself in a time-dependent manner. The results suggest that larval competition and the evolution of competitive ability in Drosophila are extremely nuanced.

evolutionary biology↗