DOI: 10.5061/dryad.2bj90
title: Data from: Fitness and morphological outcomes of many generations of hybridization in the copepod Tigriopus californicus

description: Hybridization between genetically divergent populations is an important
 evolutionary process, with an outcome that is difficult to predict. We
 used controlled crosses and freely mating hybrid swarms, followed for up
 to 30 generations, to examine the morphological and fitness consequences
 of interpopulation hybridization in the copepod Tigriopus californicus.
 Patterns of fitness in two generations of controlled crosses were partly
 predictive of long-term trajectories in hybrid swarms. For one pair of
 populations, controlled crosses revealed neutral or beneficial effects of
 hybridization, and hybrid swarm fitness always equalled or exceeded that
 of the midparent. For a second pair, controlled crosses showed F2 hybrid
 breakdown, but elevated fitness in backcrosses, and hybrid swarm fitness
 deviated both above and below that of the parentals. Nevertheless,
 individual swarm replicates exhibited divergent fitness trajectories over
 time that were not related in a simple manner to their hybrid genetic
 composition, and fixation of fitter hybrid phenotypes was not observed.
 Hybridization did not generally increase overall morphological variation,
 and underlying genetic changes may have been masked by phenotypic
 plasticity. Nevertheless, one type of hybrid swarm exhibited a repeatable
 pattern of transgressively large eggsacs, suggesting a positive effect of
 hybridization on individual fecundity. Additionally both parental and
 hybrid swarms exhibited common phenotypic trends over time, indicating
 common selective pressures in the laboratory environment. Our results
 suggest that, in a system where much work has focused on F2 hybrid
 breakdown, the long-term fitness consequences of interpopulation
 hybridization are surprisingly benign.
description: Morphological and
 survivorship data for swarmsMorphological
 measurements and offspring survivorship for hybrid swarm individuals. CTL:
 cephalothorax length; CTW: cephalothorax width; ESA: Eggsac area; CLL:
 clasper length; UL: urosome length; #Nauplii: total number of nauplii
 (alive and dead) produced from the measured eggsac; #Put: number of
 nauplii placed in petri dish for quantification of 14-day survivorship;
 #Survivors: number of survivors; SD: San Diego; PBJ: Punta Baja; SC: Santa
 Cruz; f: female; m: male; n: measurement not collected. SNP genotypes for
 individuals are archived at DRYAD
 doi:10.5061/dryad.578hrTig2_for_Dryad_Swarms.xlsxMorphological data for controlled crossesMorphological measurements for controlled cross individuals (all female). Mit: mitotype; CTL: cephalothorax length; CTW: cephalothorax width; ESA: eggsac area; SD: San Diego; PBJ: Punta Baja; SC: Santa Cruz; n: measurement not collected.Tig2_for_Dryad_Cross_Morphology.xlsxSurvivorship data for controlled crossesSurvivorship in controlled crosses. Mit: mitotype; SD: San Diego; PBJ: Punta Baja; SC: Santa Cruz; #Put: number of nauplii placed in petri dish for quantification of 14-day survivorship; #Survivors: number of survivors; n: measurement not collected.Tig2_for_Dryad_cross_survivorship.xlsx