DOI: 10.5061/dryad.d6441s7
title: Data from: Fitness decline under osmotic stress in Caenorhabditis elegans populations subjected to spontaneous mutation accumulation at varying population sizes

description: The consequences of mutations for population fitness depends on their
 individual selection coefficients and the effective population size. An
 earlier study of Caenorhabditis elegans spontaneous mutation accumulation
 lines evolved for 409 generations at three population sizes found that Ne
 = 1 populations declined significantly in fitness whereas the fitness of
 larger populations (Ne = 5, 50) was indistinguishable from the ancestral
 control under benign conditions. To test if larger MA populations harbor a
 load of cryptic deleterious mutations that are obscured under benign
 laboratory conditions, we measured fitness under osmotic stress via
 exposure to hypersaline conditions. The fitness of Ne = 1 lines exhibited
 a further decline under osmotic stress compared to benign conditions.
 However, the fitness of larger populations remained indistinguishable from
 that of the ancestral control. The average effects of deleterious
 mutations in Ne =1 lines were estimated to be 22% for productivity and 14%
 for survivorship, exceeding values previously detected under benign
 conditions. Our results suggest that fitness decline is due to large
 effect mutations which are rapidly removed via selection even in small
 populations, with implications for conservation practices. Genetic
 stochasticity may not be as potent and immediate a threat to the
 persistence of small population as other demographic and environmental
 stochastic factors.
description: Fitness measures at MA
 generation 100 under osmotic stressFitness of C. elegans
 mutation accumulation (MA lines) following 100 consecutive generations of
 spontaneous MA. The MA experiment was conducted under benign laboratory
 conditions. Fitness was tested under hyperosmotic conditions (200mM salt
 concentration in NGM plates). Manual measurements of two fitness-related
 traits, survivorship to adulthood and productivity, in long-term mutation
 accumulation (MA) lines of C. elegans maintained at population bottlenecks
 of N = 1, 10 and 100 individuals and the pre-MA ancestral control. Data is
 presented, where available for 20 N=1 lines (lines 1A-1T), ten N=10 lines
 (10A-10J), five N=100 lines (100A-100E) and 20 ancestral control lines
 (C1-C20). Where possible, data was collected for five replicates per
 experimental line. Productivity was measured by the total number of
 offspring produced by a virgin hermaphrodite over eight days or until day
 of expiration prior to eight days. Survivorship to adulthood was measured
 by isolating ten L1 larvae and determining the fraction that had survived
 to adulthood at 36 hours after initial sequestration. Survivorship data
 values range from 0-1, with a 0 value representing 100% mortality prior to
 reaching adulthood, and a value of 1 representing 100%
 survivorship.Data File
 1.pdfFitness measures at MA
 generation 172 under osmotic stressFitness of C. elegans
 mutation accumulation (MA lines) following 172 consecutive generations of
 spontaneous MA. The MA experiment was conducted under benign laboratory
 conditions. Fitness was tested under hyperosmotic conditions (200mM salt
 concentration in NGM plates). Manual measurements of two fitness-related
 traits, survivorship to adulthood and productivity, in long-term mutation
 accumulation (MA) lines of C. elegans maintained at population bottlenecks
 of N = 1, 10 and 100 individuals and the pre-MA ancestral control. Data is
 presented, where available for 20 N=1 lines (lines 1A-1T), ten N=10 lines
 (10A-10J), five N=100 lines (100A-100E) and 20 ancestral control lines
 (C1-C20). Where possible, data was collected for five replicates per
 experimental line. Productivity was measured by the total number of
 offspring produced by a virgin hermaphrodite over eight days or until day
 of expiration prior to eight days. Survivorship to adulthood was measured
 by isolating ten L1 larvae and determining the fraction that had survived
 to adulthood at 36 hours after initial sequestration. Survivorship data
 values range from 0-1, with a 0 value representing 100% mortality prior to
 reaching adulthood, and a value of 1 representing 100%
 survivorship.Data File
 2.pdfFitness measures at MA
 generation 300 under osmotic stressFitness of C. elegans
 mutation accumulation (MA lines) following 300 consecutive generations of
 spontaneous MA. The MA experiment was conducted under benign laboratory
 conditions. Fitness was tested under hyperosmotic conditions (200mM salt
 concentration in NGM plates). Manual measurements of two fitness-related
 traits, survivorship to adulthood and productivity, in long-term mutation
 accumulation (MA) lines of C. elegans maintained at population bottlenecks
 of N = 1, 10 and 100 individuals and the pre-MA ancestral control. Data is
 presented, where available for 20 N=1 lines (lines 1A-1T), ten N=10 lines
 (10A-10J), five N=100 lines (100A-100E) and 20 ancestral control lines
 (C1-C20). Where possible, data was collected for five replicates per
 experimental line. Productivity was measured by the total number of
 offspring produced by a virgin hermaphrodite over eight days or until day
 of expiration prior to eight days. Survivorship to adulthood was measured
 by isolating ten L1 larvae and determining the fraction that had survived
 to adulthood at 36 hours after initial sequestration. Survivorship data
 values range from 0-1, with a 0 value representing 100% mortality prior to
 reaching adulthood, and a value of 1 representing 100%
 survivorship.Data File
 3.pdfFitness measures at MA
 generation 409 under osmotic stressFitness of C. elegans
 mutation accumulation (MA lines) following 409 consecutive generations of
 spontaneous MA. The MA experiment was conducted under benign laboratory
 conditions. Fitness was tested under hyperosmotic conditions (200mM salt
 concentration in NGM plates). Manual measurements of two fitness-related
 traits, survivorship to adulthood and productivity, in long-term mutation
 accumulation (MA) lines of C. elegans maintained at population bottlenecks
 of N = 1, 10 and 100 individuals and the pre-MA ancestral control. Data is
 presented, where available for 20 N=1 lines (lines 1A-1T), ten N=10 lines
 (10A-10J), five N=100 lines (100A-100E) and 20 ancestral control lines
 (C1-C20). Where possible, data was collected for five replicates per
 experimental line. Productivity was measured by the total number of
 offspring produced by a virgin hermaphrodite over eight days or until day
 of expiration prior to eight days. Survivorship to adulthood was measured
 by isolating ten L1 larvae and determining the fraction that had survived
 to adulthood at 36 hours after initial sequestration. Survivorship data
 values range from 0-1, with a 0 value representing 100% mortality prior to
 reaching adulthood, and a value of 1 representing 100%
 survivorship.Data File
 4.pdf