Can developmental plasticity shape sexual competition and promote reproductive isolation?

Environmental factors such as dietary nutrients can shape the expression of developmentally plastic sexual traits in many species. However, while there has been extensive research into the developmental plasticity of sexual traits at the individual level, the broader consequences of this variation at the population scale remain poorly understood. Here, we asked whether plastic responses to the developmental environment can shape sexual competition and initiate reproductive isolation between populations. We reared neriid flies, Telostylinus angusticollis, on nutrient-rich and nutrient-poor larval diets, generating adult flies that differed in body size and secondary sexual trait expression. We then investigated sexual competition in experimental populations from each developmental environment, and tested for reproductive isolation between flies from mismatched environments. We found that, compared with poor-diet populations, rich-diet populations exhibited more frequent and escalated mal..., Rearing and Culturing of Flies
The individuals used in the experiments described below were second-generation individuals reared from T. angusticollis collected from Fred Hollows Reserve in Randwick, New South Wales, Australia (33˚54’44.04”S, 151˚14’52.14”E). The flies were housed in population cages with moist cocopeat and were given three separate petri dishes containing brown sugar, yeast, and oviposition medium. The oviposition medium consisted of a nutrient-rich diet (as described below) which had been left to mould for approximately 4 days and then mixed to encourage oviposition. The cages were sprayed with reverse osmosis (RO) water every second day. To generate focal flies for experiments, eggs were collected from oviposition medium  in stock cages and transferred to 500 mL jars containing 200 mL of either a nutrient-rich diet (“rich diet”) or a nutrient-poor diet (“poor diet”) to represent developmental environments differing in availability of macronutrients. Approximately 20 ..., , # Can developmental plasticity shape sexual competition and promote reproductive isolation?

[https://doi.org/10.5061/dryad.xksn02vq2](https://doi.org/10.5061/dryad.xksn02vq2)

#### Data files:

(1) **BodySize**: Individual body size (wing length) measurements for the focal males and females used in the study.

(2) **SexCompData**: Individual behavioural data for males and females in the Sexual Competition Experiment, grouped by replicate population, day (block), and larval diet treatment.

(3) **SexCompSummary**: Summary statistics (means or counts) of behavioural data from the Sexual Competition Experiment, grouped by day and larval diet treatment. Most analyses for this experiment were carried out on means or counts for replicate populations using this data file.

(4) **Rejections_Paired**: Rejection behaviours by females (from the Sexual Competition Experiment) in wide form for a Wilcoxon matched-pairs test, with day as the grouping factor.

(5) **RIData**: Data from the Reproductiv...