DOI: 10.5061/dryad.r4xgxd297
title: Data from: Evidence for the evolution of thermal tolerance but not desiccation tolerance in response to hotter, drier city conditions in a cosmopolitan, terrestrial isopod

description: Cities are often hotter and drier compared with nearby undeveloped areas,
 but how organisms respond to these multifarious stressors associated with
 urban heat islands is largely unknown. Terrestrial isopods are especially
 susceptible to temperature and aridity stress as they have retained highly
 permeable gills from their aquatic ancestors. We performed a
 two‐temperature common garden experiment with urban and rural populations
 of the terrestrial isopod, Oniscus asellus , to uncover
 evidence for plastic and evolutionary responses to urban heat islands. We
 focused on physiological tolerance traits including tolerance of heat,
 cold and desiccation. We also examined body size responses to urban heat
 islands, as size can modulate physiological tolerances. We found that
 different mechanisms underlie responses to urban heat islands. While
 evidence suggests urban isopods may have evolved higher heat tolerance,
 urban and rural isopods had statistically indistinguishable cold and
 desiccation tolerances. In both populations, plasticity to warmer rearing
 temperature diminished cold tolerance. Although field‐collected urban and
 rural isopods were the same size, rearing temperature positively affected
 body size. Finally, larger size improved desiccation tolerance, which
 itself was influenced by rearing temperature. Our study demonstrates how
 multifarious changes associated with urban heat
 islands, i.e. heat and aridity, will not necessarily
 contribute to contemporary evolution in each of the corresponding
 physiological traits.
description: <strong>isopod_thermal tolerance</strong>
 This dataset contains 14 columns, including "colonyID",
 "individual", "isa", "site",
 "thermal.tolerance.trait", "thermal.tolerance",
 "tester", "heat.block", "date.tt",
 "time.of.day", "age.days", "initial.weight",
 "habitat", and "treatment". Each row of the dataset
 represents the response of an individual isopod. colonyID – a unique but
 arbitrary alpha-numeric identifier for each group of isopods reared
 together in the lab (i.e., a replicate); multiple individual isopods were
 tested from the same replicate. isa - a continuous numerical value
 describing the amount of impervious surface area in a given collection
 site at a 1km resolution based on the Elvidge et al. 2007 dataset. site -
 a shorthand name given to the collection site from which the F1
 isopod's parental generation were collected in the
 field. thermal.tolerance.trait – a categorical variable describing whether
 the critical thermal minimum (ctmin) or critical thermal maximum (ctmax)
 was assessed on the individual isopod. thermal.tolerance – a continuous
 numeric value describing either the ctmax or ctmin. Values are presented
 in units of degrees Celsius. tester - initials denoting the person who
 conducted the thermal tolerance test for each individual isopod.
 heat.block - denotes which of the two heat blocks (of the same model and
 specification) were used in conducting the thermal tolerance test for each
 individual isopod. date.tt – the date (month/day/year) that the thermal
 tolerance assessment was conducted. time.of.day - the time of day
 (measured on a 24-hour clock) at which the thermal tolerance tests were
 conducted. age.days - the number of days an individual isopod spent in a
 temperature rearing treatment, that is, the number of days between said
 isopod's birth and thermal tolerance trial. initial.weight - mass in
 g of each individual isopod just prior to thermal tolerance
 trials. habitat - a categorical variable denoting whether the individual
 F1 isopod's parents derived from an urban or rural field collection
 site. treatment - a categorical variable denoting whether an individual
 isopod was reared at a 21 or 29-degree temperature rearing treatment.
 Values are presented in units of degrees Celsius
 <strong>isopod_desiccation_tolerance</strong> This dataset contains 15 columns, including "colonyID", "individual", "isa", "site", "mins.dead", "tester", "desiccator", "date", "died", "age.days", "time.of.day", "initial.weight", "habitat", "habitat.n", and "treatment". Each row of the dataset represents the response of an individual isopod. colonyID – a unique but arbitrary alpha-numeric identifier for each group of isopods reared together in the lab (i.e., a replicate); multiple individual isopods were tested from the same replicate. isa - a continuous numerical value describing the amount of impervious surface area in a given collection site at a 1km resolution based on the Elvidge et al. 2007 dataset. site - a shorthand name given to the collection site from which the F1 isopod's parental generation were collected in the field. mins.dead – a continuous numeric value describing the amount of time (in minutes) it took an individual isopod to reach its desiccation tolerance endpoint under low humidity conditions. tester - initials denoting the person who conducted the desiccation tolerance test for each individual isopod. desiccator - denotes which of the two desiccators (of the same model and specification) were used in conducting the desiccation tolerance test for each individual isopod. date – the date (month/day/year) that the desiccation tolerance assessment was conducted. died - the date the desiccation tolerance trial was conducted for a given isopod. age.days - the number of days an individual isopod spent in a temperature rearing treatment, that is, the number of days between said isopod's birth and desiccation tolerance trial. time.of.day - the time of day (measured on a 24-hour clock) at which the desiccation tolerance tests were conducted. initial.weight - mass in g of each individual isopod just prior to deisccation tolerance trials. habitat - a categorical variable denoting whether the individual F1 isopod's parents derived from an urban or rural field collection site. habitat.n - a categorical variable with "0" representing the rural habitat and "1" representing the urban habitat. treatment - a categorical variable denoting whether an individual isopod was reared at a 21 or 29-degree temperature rearing treatment. Values are presented in units of degrees Celsius <strong>combined_age_body_mass</strong> This dataset contains 5 columns, including "colonyID", "age.days", "initial.weight", "habitat", and "treatment". Each row of the dataset represents the response of an individual isopod. colonyID – a unique but arbitrary alpha-numeric identifier for each group of isopods reared together in the lab (i.e., a replicate); multiple individual isopods were tested from the same replicate. age.days - the number of days an individual isopod spent in a temperature rearing treatment, that is, the number of days between said isopod's birth and its tolerance trial. initial.weight - mass in g of each individual isopod just prior to tolerance trials. habitat - a categorical variable denoting whether the individual F1 isopod's parents derived from an urban or rural field collection site. treatment - a categorical variable denoting whether an individual isopod was reared at a 21 or 29-degree temperature rearing treatment. Values are presented in units of degrees Celsius