DOI: 10.5061/dryad.4qrfj6qqg
title: Resilient by nature: Managed rearing does not erode physiochemical tolerances of an extremophile fish

description: Populations in managed care are valuable resources that complement in situ
 conservation efforts, but adaptation to captive conditions and other
 domestication effects present concerns for conservation. Many populations
 of fish adapted to sulfide springs are highly endemic and imperiled,
 potentially benefiting from ex situ conservation efforts. However, it is
 challenging to maintain natural conditions in the laboratory as hydrogen
 sulfide (H2S) is highly toxic and coincides with severe hypoxia. Here, we
 tested whether long-term standardized rearing of sulfide spring fishes
 leads to the loss of H2S and hypoxia tolerances. We compared the
 tolerances of Poecilia mexicana (Poeciliidae) from sulfidic and
 non-sulfidic habitats that were reared in the laboratory for 18 years and
 wild-caught fish from the same sites. Both H2S and hypoxia tolerances were
 maintained in laboratory-reared fish from the sulfidic habitat.
 Additionally, fish from a non-sulfidic cave site, evolutionarily derived
 from a sulfidic population, exhibited higher H2S and hypoxia tolerances
 than fish from the non-sulfidic surface site. While domestication can lead
 to the loss of adaptations to extreme environmental conditions, our
 research indicates this is not a concern in laboratory stocks of P.
 mexicana, which retained tolerance of H2S and hypoxia despite not
 experiencing these stressors for ~40 generations.
description: # Resilient by nature: Managed rearing does not erode physiochemical
 tolerances of an extremophile fish Dataset DOI:
 [10.5061/dryad.4qrfj6qqg](https://doi.org/10.5061/dryad.4qrfj6qqg) ##
 Description of the data and file structure This dataset includes measures
 of hypoxia and hydrogen sulfide tolerance in laboratory-reared and
 wild-caught populations of *Poecilia mexicana* (Lab_adapted_loe.xlsx) and
 environmental conditions at the collection site measured in 2025
 (env_2025.xlsx). The two Excel files are analyzed using the R script
 LOE_labadapted_final.Rmd. ### Files and variables #### File:
 Lab_adapted_loe.xlsx **Description:** This dataset includes information on
 the tolerance trials for wild-caught and laboratory-reared fish. #####
 Variables: * Date: Date of trial * Time: Time of trial * Trial: Trial
 number * Trial_Type: Type of trial (hypoxia tolerance or hydrogen sulfide
 tolerance) * Pop: Population= PS5, Luna, PS10, PS2, Oxo, PS13, Bonita *
 LOE: time until loss of equilibrium (s) * SL_mm: Standard length (measured
 from snout to caudal peduncle in mm) * Habitat: Habitat of origin of fish
 (Sulfidic Cave, Non-sulfidic cave, or Non-Sulfidic surface) * Location:
 Sampling location (Lab=laboratory-reared, Field=Wild-caught) * Survival:
 Did fish last the entire time of the trial (62 minutes) 0= lost
 equilibrium, 1= did not lose equilibrium * Notes: notes about the trial
 #### File: env_summary.xlsx **Description:** This dataset includes
 environmental information collected at the sites in 2025. ##### Variables:
 * Population: Site where environmental variables were collected (Bonita,
 Luna, or PS10) * Date: Collection date * Temperature: Temperature measured
 in °C * DO: Dissolved oxygen measured in mg/L * ph: pH * Conductivity:
 Specific conductivity measured in µS/cm * Sulfide: total sulfides measured
 in µM; negative values indicate that sulfides were not detectable in the
 sample. #### File: LOE_labadapted_final.Rmd **Description:** This R script
 is used to analyze the two Excel files. ## Code/software This data was
 analyzed using R version 4.5.0.