DOI: 10.5061/dryad.h9w0vt4sb
title: Weak local adaptation to climate in seedlings of a deciduous conifer suggests limited benefits and risks of assisted gene flow

description: Assisted migration provides a potential solution to mitigate the
 increasing risks of forest maladaptation under climate change. Western
 larch (Larix occidentalis Nutt.) is a deciduous conifer species undergoing
 assisted migration beyond its natural range in British Columbia into areas
 that have become suitable based on climatic niche modelling. We
 established a seedling common garden experiment in raised beds in a warm
 location outside the natural range for three growing seasons, with 52
 natural populations from across the species range and 28 selectively-bred
 families from British Columbia. Intraspecific genetic variation in growth,
 phenology and cold hardiness was analyzed to test for signals of local
 adaptation and the effects of selective breeding to better understand the
 implications for assisted migration and breeding for future climates. We
 found weak differentiation among populations in all traits, with the
 proportion of additive genetic variance (QST) values ranging from 0.10 to
 0.28. Cold hardiness had the weakest population differentiation and
 exhibited no clines with geographic or climatic variables. Selective
 breeding for faster growth has maintained genetic variation in bud flush
 phenology and cold hardiness despite delaying bud set. The weak signals of
 local adaptation we found in western larch seedlings highlights that
 assisted gene flow among populations is likely to have limited benefits
 and risks for mitigating maladaptation with climate change. Our findings
 suggest that assisted migration outside of the range and selective
 breeding may be important management strategies for western larch for
 future climates.
description: # Weak local adaptation to climate in seedlings of a deciduous conifer
 suggests limited benefits and risks of assisted gene flow
 [https://doi.org/10.5061/dryad.h9w0vt4sb](https://doi.org/10.5061/dryad.h9w0vt4sb) ## Description of the data and file structure This dataset contains original phenotypic trait data for individual seedlings from a common garden experiment of western larch. The data includes height growth, bud flush and bud set dates, and cold injury values collected during the 2021 growing season. Please see the manuscript by Roskilly & Aitken 2024 for details on how trait data was collected. Geographic coordinates and source climates for natural populations can be found in Table S1.  ### Files and variables #### File: Roskilly\_\_\_Aitken\_2024\_EVA\_trait\_data.zip **Description:**  * seedlot = identification number used for each seedlot representing a natural population or full-sib family * id = identification number for each individual seedling * block = each block (4 total) which contained 240 experimental seedlings each  * position = sequential position of each seedling within a block * pos_x = x coordinate representing spatial position within the entire experiment * pos_y = y coordinate representing spatial position within the entire experiment * ht = height (cm) * date = date of measurement (height) or observation (bud flush or bud set) * stage = stage of bud set to account for reflushing (1 = initial, 2= second, 3=third, 4=final bud set) * week = week when cold injury was measured (two weeks of data were averaged) * temp = test temperature for each cold injury sample (degrees C) * ec1 = electrolytic leakage measured directly after test temperature exposure (4 degrees C = control) * ec2 = total electrolytic leakage after heat killing at 95 degrees C for at least 12 hours * rt = ratio of electrolytic leakage after test temperature relative to heat killing  * missing values are indicated by "NA" or blank cells  * it = percentage of cold injury using the ratio of electrolytic leakage after freezing relative to total leakage after heat killing at 95 °C between test and control samples ## Code/software Files were created in Microsoft Excel v16.87.