Adaptation to larval crowding in Drosophila ananassae and Drosophila nasuta nasuta: increased larval competitive ability without increased larval feeding rate

Nagarajan, Archana and Natarajan, Sharmila Bharathi and Jayaram, Mohan and Thammanna, Ananda and Chari, Sudarshan and Bose, Joy and Jois, Shreyas V and Joshi, Amitabh (2016) Adaptation to larval crowding in Drosophila ananassae and Drosophila nasuta nasuta: increased larval competitive ability without increased larval feeding rate. In: JOURNAL OF GENETICS, 95 (2). pp. 411-425.

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Abstract

The standard view of adaptation to larval crowding in fruitflies, built on results from 25 years of multiple experimental evolution studies on Drosophila melanogaster, was that enhanced competitive ability evolves primarily through increased larval feeding and foraging rate, and increased larval tolerance to nitrogenous wastes, at the cost of efficiency of food conversion to biomass. These results were at odds from the predictions of classical K-selection theory, notably the expectation that selection at high density should result in the increase of efficiency of conversion of food to biomass, and were better interpreted through the lens of alpha-selection. We show here that populations of D. ananassae and D. n. nasuta subjected to extreme larval crowding evolve greater competitive ability and pre-adult survivorship at high density, primarily through a combination of reduced larval duration, faster attainment of minimum critical size for pupation, greater time efficiency of food conversion to biomass and increased pupation height, with a relatively small role of increased urea/ammonia tolerance, if at all. This is a very different suite of traits than that seen to evolve under similar selection in D. melanogaster, and seems to be closer to the expectations from the canonical theory of K-selection. We also discuss possible reasons for these differences in results across the three species. Overall, the results reinforce the view that our understanding of the evolution of competitive ability in fruitflies needs to be more nuanced than before, with an appreciation that there may be multiple evolutionary routes through which higher competitive ability can be attained.

Item Type:	Journal Article
Publication:	JOURNAL OF GENETICS
Publisher:	INDIAN ACAD SCIENCES, BANGALORE
Additional Information:	Copy right for this article belongs to the INDIAN ACAD SCIENCES, BANGALORE
Department/Centre:	Division of Biological Sciences > Molecular Reproduction, Development & Genetics
Date Deposited:	19 Aug 2016 05:49
Last Modified:	19 Aug 2016 05:49
URI:	http://eprints.iisc.ac.in/id/eprint/54377

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