DOI: 10.5061/dryad.36746
title: Data from: Loss of heterosis and family-dependent inbreeding depression in plant performance and resistance against multiple herbivores under drought stress

description: 1. Inbreeding depression (ID), outbreeding depression (OD) and heterosis
 can occur concurrently in plant populations. ID often increases under
 environmental stress, but the combined effects of inbreeding, outbreeding
 between populations and environmental stress, such as drought, on plant
 performance and herbivore resistance remain unclear. 2. In order to
 determine environment-dependent and family-dependent ID, OD and heterosis
 we conducted a common garden experiment with plants from five populations
 of Brassica nigra. Inbred, within-population outbred and
 between-population outbred plant families were exposed to drought or
 ambient water levels. We recorded the abundance and damage caused by
 specialist herbivores from contrasting feeding guilds, i.e. the
 phloem-feeding Brevicoryne brassicae, the leaf-chewing Psylliodes
 chrysocephalus and the stem-boring Ceutorhynchus quadridens larvae. 3.
 Drought stress had negative effects on growth, herbivore resistance and
 resistance against B. brassicae and positive effects on investments in
 reproductive output and plant secondary metabolites (sinigrin). We found
 drought stress-induced loss of heterosis for plant height and investment
 in reproductive output. Between-population outbred plants were more
 sensitive to drought stress in terms of above-ground biomass compared to
 within-population outbred plants. 4. Drought and inbreeding
 synergistically negatively influenced traits related to growth and
 reproductive output (environment-dependent inbreeding depression, EDID).
 There was high variation among families within populations in the degree
 of ID and EDID. Genetic variation in EDID could buffer the negative
 effects of genetic stress associated with habitat fragmentation and
 concurrent environmental stress. In order to capture fully the effects of
 both inbreeding and between-population outbreeding under stress the
 different spatial scales of the effects of inbreeding and
 between-population outbreeding should be taken into account. 5. Synthesis.
 Our results indicate that drought stress influences not only inbreeding
 depression (ID), but also heterosis. These findings shed new light on the
 combined effects of anthropogenic environmental change and the genetic
 consequences of habitat fragmentation on plants and their interactions
 with other organisms. Conservation programmes aiming to restore
 genetically degraded populations with the translocation of individuals
 between populations should consider environmental stress as a risk factor.
description: Common garden
 dataThe file contains all
 data used in the statistical analyses described in the materials and
 methods section of the article. Abbreviated headlines are as follows:
 "Pop"=Population; "Code"= number of family associated
 with the population; "Fam"=family; "Number"=number of
 each plant within a family; "PB"=plunge bed;
 "Treatment"=water treatment ("D"=drought stress;
 "W"= ambient water treatment); "Beetles"=number of
 beetles; "Aphids_(cm)"=cm covered by aphids;
 "Aph"=Aphids_(cm)+0.1; "Stem"=number of holes produced
 by C.quadridens larvae in the plant stem; "Weight"=above-ground
 biomass (g); "Infl."=number of inflorescences;
 "Damage"=percent damage by herbivores;
 "Height_Aft"=plant height.Common
 garden_Dryad.xlsx