Data from: Postmating-prezygotic isolation between two allopatric populations of Drosophila montana: fertilisation success differs under sperm competition

Postmating but prezygotic (PMPZ) interactions are increasingly recognized as a potentially important early-stage barrier in the evolution of reproductive isolation. A recent study described a potential example between populations of the same species: single matings between Drosophila montana populations resulted in differential fertilisation success because of the inability of sperm from one population (Vancouver) to penetrate the eggs of the other population (Colorado). As the natural mating system of D. montana is polyandrous (females remate rapidly), we set up double matings of all possible crosses between the same populations to test whether competitive effects between ejaculates influence this PMPZ isolation. We measured premating isolation in no-choice tests, female fecundity, fertility and egg-to-adult viability after single and double matings as well as second-male paternity success (P2). Surprisingly, we found no PMPZ reproductive isolation between the two populations under a competitive setting, indicating no difficulty of sperm from Vancouver males to fertilize Colorado eggs after double matings. While there were subtle differences in how P2 changed over time, suggesting that Vancouver males' sperm are somewhat less competitive in a first-male role within Colorado females, these effects did not translate into differences in overall P2. Fertilisation success can thus differ dramatically between competitive and noncompetitive conditions, perhaps because the males that mate second produce higher quality ejaculates in response to sperm competition. We suggest that unlike in more divergent species comparisons, where sperm competition typically increases reproductive isolation, ejaculate tailoring can reduce the potential for PMPZ isolation when recently diverged populations interbreed.Used SNP markersThe columns correspond to marker name, usage in parentage analysis (parents and offspring), usage in population analysis, the Drosophila virilis gene the marker maps to, the relevant D. virilis chromosome and the top blast hit of the marker by using Blast2GOAdditional file1.xlsxData on females' first matingThe data file "First mating" includes all females that mated in the first mating and the number of eggs they laid and the number of offspring that eclosed from eggs laid after the first mating.First_mating.xlsxcopdur2_mating_latency2The data file "copdur2_mating_latency2" includes females that remated and for which we recorded copulation duration of the 2nd mating. It also includes and the number of eggs they laid and the number of offspring that eclosed from eggs laid after the second mating.Data used in P2 analysisThe file "Paternities no zero P2" includes females that were used in P2 analyses.paternities_nozero_P2.xlsxAll_matingsThe file "All matings" lists all females that mated in the first mating as well as their behaviour after it. This file should be used cautiously as it may not be exactly the same as the files above that have been used in statistical analysis (some wrongly typed numbers have been corrected in the above files). We give this file for the purpose of checking which females remated and which did not