DOI: 10.5061/dryad.rr4xgxdhb
title: Species differences in reproductive timing and egg load in two fly species adapted to different host plants

description: Selection acts on reproductive timing and egg number to maximize
 reproductive success based on available resources. Species often vary in
 these life history traits due to differences in trait variation and local
 selection pressures, especially when species are adapted to different
 environments. Yet, species may share similar life history traits given
 common correlations, such as a positive relationship between body size and
 fecundity. In this study, we tested whether species adapted to different
 environments differ in their reproductive timing and egg load using two
 species of Tephritid fruit flies: Rhagoletis pomonella adapted to downy
 hawthorn and Rhagoletis suavis adapted to black walnut. In both species,
 older females were more likely to produce eggs and have more eggs.
 However, reproductive timing differed between species; hawthorn flies
 produced eggs earlier than walnut flies. In contrast to the common
 association of larger body size with earlier reproduction and higher egg
 counts, we did not find that adult female body size predicted reproductive
 timing in either species. In hawthorn flies with earlier reproductive
 maturity, body size did not affect egg number. For walnut flies with later
 reproductive maturity, larger females produced more eggs. Our findings
 suggest that while time to accumulate resources and develop eggs is a
 common constraint, reproductive strategies are likely shaped by adaptation
 to specific host plants. Our study highlights the complex interaction
 between selection pressures and trait correlations in shaping life history
 traits across species.
description: # Species differences in reproductive timing and fecundity in two fly
 species adapted to different host plants
 [https://doi.org/10.5061/dryad.rr4xgxdhb](https://doi.org/10.5061/dryad.rr4xgxdhb) ## Description of the data and file structure We collected wild flies as larvae in their host fruits (hawthorn and walnut) and reared them in environmental chambers in the lab until eclosion as adults. We housed adults until a series of sampled ages ranging from 10-58 days. Females were frozen and then measured for body length under a high magnification dissecting microscope. We then dissected the ovaries and counted eggs. ### Files and variables #### File: Rhagoletis\_haw\_walnut\_fecundity\_to-publish.xlsx **Description:** Body size and fecundity for hawthorn and walnut flies ##### Variables * population (different 2-3 letter code for each population; WS and EL are in Michigan, LBL is in Kentucky, and CHE is in Colorado) * expt (expt 1 or 2, methods described in the manuscript) * fruit (host fruit: hawthorn or walnut) * temp (weekly temperature programs or constant temperatures within each fall, winter, and spring season; details explained in methods of the manuscript) * age_lower (for flies in expt2, flies were collected every 2-3 days, so ages ranged from a minimum to maximum) * age_upper * age_avgYN (for flies in expt2, we averaged the lower and upper ages) * age (exact age for expt1 flies and the average age for expt2 flies) * groupedYN (flies were housed in groups of 3 females and 2 males: Y; flies were housed alone: N; all expt1 flies and some expt2 flies were housed in groups) * tibia_length (length of the righthand side rear leg tibia in mm, measured on a high magnification dissecting microscope with associated software) * intereye_width (the width of the smallest distance between the eyes on the ventral side in mm) * egg_count (egg count including females with no eggs) * egg_count_nonzero    (egg count excluding females with no eggs) * eggsYN (absence: 0 or presence: 1 of eggs) na: not applicable ## Code/software R