DOI: 10.5061/dryad.w3r22813x
title: Niche conservatism and sympatric parallel evolution may help to maintain eight nascent tree taxa along a sharp elevation gradient

description: Patterns of niche partitioning among closely related taxa, such as those
 in incipient adaptive radiations, can provide clues into how niches are
 created, partitioned, and integrated over ecological and evolutionary time
 scales. Hawaiian Metrosideros is a ~3-MYO adaptive radiation of
 trees that dominates the Hawaiian Islands in continuous stands within
 islands and allows examination of niche partitioning at the early stages
 of adaptive radiation. We monitored growth and survivorship in a
 greenhouse over two years of seedlings derived from open-pollinated fruits
 of eight Metrosideros taxa distributed along the elevation
 gradient of Koʻolau Volcano, Oʻahu, under four combinations of light and
 phosphorus. We included four glabrous taxa, representing mixed lineages,
 and four pubescent taxa, representing a single, Oʻahu-endemic lineage and
 tested hypotheses of differentiation among taxa and between glabrous and
 pubescent groups.  Several phenotypic traits were measured at the
 start and end of the two-year experiment, with additional measures at the
 end.  Initial and final morphological measures were used to
 assess the retention of taxon-diagnostic traits at the two stages and the
 related measure of plasticity after two years of growing under contrasting
 environmental conditions. Variation in relative growth rates and
 survivorship was examined across taxa, between glabrous and pubescent
 groups, and across relative elevations within Ko`olau Volcano (1-4: low to
 high).  Finally, Pianka's niche overlap index was estimated
 for all taxon pairs.
description: # Niche conservatism and sympatric parallel evolution may help to maintain
 eight nascent tree taxa along a sharp elevation gradient Dataset DOI:
 [10.5061/dryad.w3r22813x](10.5061/dryad.w3r22813x) ## Description of the
 data and file structure These 4 files include seedling morphological data
 recorded at the start and end of the 2-year greenhouse experiment in which
 seedlings of 8 Oahu Metrosideros taxa were grown under 4 combinations of
 light and phosphorus.  Also included are measures of relative growth rate
 (RGR) and biweekly survivorship throughout the experiment. ### Files and
 variables #### File: 1\_Stacy\_Ostertag\_initial\_morphology.csv
 **Description:** Morphology of seedlings at the start of the experiment.
 ##### Variables * abs_ID: (character) = absolute plant ID *
 light: (character) = Low, High * phosphorus: (character) = Low, High *
 taxon: (character) = eight letters representing eight taxa B =
 *Metrosideros polymorpha* race B, C = *M. polymorpha* race C, F = *M.
 polymorpha* race F, I = *M. polymorpha* variety *incana*, L = *M.
 polymorpha* race L, R = *M. rugosa*, T = *M. tremuloides*, Z = *M.
 polymorpha* race Z.  Taxon descriptions and diagnostic key are provided
 in: Stacy, E. A., T. Sakishima, H. Tharp, and N. Snow. 2020. Isolation of
 *Metrosideros* ('Ohi'a) taxa on O`ahu increases with elevation
 and extreme environments. Symposium Issue; Journal of Heredity 111:
 103-118. * family: (character) = ID of maternal tree from which seeds were
 sampled to produce seedlings for study * elevation_category: (numeric) =
 1,2,3,4 for lowest to highest * glabrous_or_pubescent: (character) = G, P
 for glabrous, pubescent * initial_measure_date: (MM/DD/YEAR) = date of
 initial morphological measurements * no_stems: (numeric) = number of stems
 * main_stem_length_cm: (numeric) = main stem length (cm) *
 cumulative_stem_length_cm: (numeric) = cumulative stem length (cm) *
 no_leaves: (numeric) = number of leaves * leaf_length_mm: (numeric) = leaf
 length (cm) * leaf \_width_mm: (numeric) = leaf width (cm) *
 leaf_shape(llength/lwidth): (numeric) = leaf shape (leaf length/leaf
 width) * petioles: 0,1 for absent, present * pot_type: (character) = pot,
 dibble #### File: 2\_Stacy\_Ostertag\_final\_morphology\_and\_growth.csv
 **Description:** The initial morphology measures above are included in
 this file as well as measures taken at end of the experiment. #####
 Variables * abs_ID: (character) = absolute plant ID * light : (character)
 = Low, High * phosphorus: (character) = Low, High * taxon: (character) =
 eight letters representing eight taxa B = *Metrosideros polymorpha* race
 B, C = *M. polymorpha* race C, F = *M. polymorpha* race F, I = *M.
 polymorpha* variety *incana*, L = *M. polymorpha* race L, R = *M. rugosa*,
 T = *M. tremuloides*, Z = *M. polymorpha* race Z.  Taxon descriptions and
 diagnostic key are provided in: Stacy, E. A., T. Sakishima, H. Tharp, and
 N. Snow. 2020. Isolation of *Metrosideros* ('Ohi'a) taxa on
 O`ahu increases with elevation and extreme environments. Symposium Issue;
 Journal of Heredity 111: 103-118. * family: (character) = ID of maternal
 tree from which seeds were sampled to produce seedlings for study *
 initial_measure_date: (MM/DD/YEAR) = date of initial morphological
 measurements * no_stems_initial: (numeric) = number of stems *
 no_stems_final: (numeric) = final number of stems *
 RGR_no_stems: (numeric) = number-of-stems relative growth rate *
 main_stem_length_cm_initial: (numeric) = main stem length (cm) *
 main_stem_length_cm_final: (numeric) = final main stem length (cm) *
 RGR_main_stem_length: (numeric) main-stem-length relative growth rate *
 cumulative_stem_length_cm_initial: (numeric) = cumulative stem length (cm)
 * cumulative_stem_length_cm_final: (numeric) = final cumulative stem
 length (cm) * RGR_cum_stem_length:  (numeric) cumulative-stem-length
 relative growth rate * no_leaves_initial: (numeric) = number of leaves *
 no_leaves_final: (numeric) = final number of leaves * RGR_no_leaves:
 (numeric) number-of-leaves relative growth rate * leaf_length_mm_initial:
 (numeric) = leaf length (cm) * leaf_length_mm_final: (numeric) = final
 leaf length (cm) * leaf \_width_mm_initial: (numeric) = leaf width (cm) *
 leaf \_width_mm_final: (numeric) = final leaf width (cm) *
 leaf_shape_final: (numeric) = leaf shape (leaf length/leaf width) at final
 * petioles_initial: 0,1 for absent, present * petioles_final: 0,1 for
 absent, present at final * mature_phenotype_reached_at_final?: 0,1 for no,
 yes * aerial_root_length_cm_final: aerial root length (cm) at final *
 aer_root_length/cumulative_stem_length_final: [aerial root length
 (cm)]/[cumulative stem length (cm)] * leaf_pubescence_score_final: abaxial
 leaf pubescence score at final (0, 0.5, 1, 1.5, 2, such that 0 = glabrous;
 0.5, 1, 1.5 = pubescence that rubs off with little, moderate, and strong
 effort, respectively; and 2 = permanent pubescence) *
 pot_type: (character) = pot, dibble #### File:
 3\_Stacy\_Ostertag\_survivorship.csv **Description:** The descriptor
 variables in the first 7 columns are identical to those in the above
 files.  The remaining columns indicate mortality (with an X) and its
 timing across the 2-year experiment.  The final column,
 "dead_or_alive_1July15" indicates the state of each seedling at
 the end of the experiment (0,1 for dead, alive). ##### Variables *
 abs_ID: (character) = absolute plant ID * light : (character) = Low, High
 * phosphorus: (character) = Low, High * taxon: (character) = eight letters
 representing eight taxa B = *Metrosideros polymorpha* race B, C = *M.
 polymorpha* race C, F = *M. polymorpha* race F, I = *M.
 polymorpha* variety *incana*, L = *M. polymorpha* race L, R = *M. rugosa*,
 T = *M. tremuloides*, Z = *M. polymorpha* race Z.  Taxon descriptions and
 diagnostic key are provided in: Stacy, E. A., T. Sakishima, H. Tharp, and
 N. Snow. 2020. Isolation of *Metrosideros* ('Ohi'a) taxa on
 O`ahu increases with elevation and extreme environments. Symposium Issue;
 Journal of Heredity 111: 103-118. * family: (character) = ID of maternal
 tree from which seeds were sampled to produce seedlings for study *
 initial_measure_date: (date) = date of initial morphological measurements
 * pot_type: (character) = pot, dibble * mortality_8/12/2013: blank or X
 for alive or dead, respectively * 8/30/2013: blank or X for alive or dead,
 respectively * 9/17/2013: blank or X for alive or dead, respectively *
 10/1/2013: blank or X for alive or dead, respectively * 10/14/2013: blank
 or X for alive or dead, respectively * 10/30/2013: blank or X for alive or
 dead, respectively * 11/13/2013: blank or X for alive or dead,
 respectively * 11/27/2013: blank or X for alive or dead, respectively *
 12/18/2013: blank or X for alive or dead, respectively * 1/7/2014: blank
 or X for alive or dead, respectively * 1/28/2014: blank or X for alive or
 dead, respectively * 2/14/2014: blank or X for alive or dead, respectively
 * 3/1/2014: blank or X for alive or dead, respectively * 3/15/2014: blank
 or X for alive or dead, respectively * 4/1/2014: blank or X for alive or
 dead, respectively * 4/15/2014: blank or X for alive or dead, respectively
 * 5/1/2014: blank or X for alive or dead, respectively * 5/15/2014: blank
 or X for alive or dead, respectively * 6/1/2014: blank or X for alive or
 dead, respectively * 6/15/2014: blank or X for alive or dead, respectively
 * 7/1/2014: blank or X for alive or dead, respectively * 7/15/2014: blank
 or X for alive or dead, respectively * 8/1/2014: blank or X for alive or
 dead, respectively * 8/15/2014: blank or X for alive or dead, respectively
 * 9/1/2014: blank or X for alive or dead, respectively * 9/15/2014: blank
 or X for alive or dead, respectively * 10/1/2014: blank or X for alive or
 dead, respectively * 10/15/2014: blank or X for alive or dead,
 respectively * 11/1/2014: blank or X for alive or dead, respectively *
 11/15/2015: blank or X for alive or dead, respectively * 12/1/2014: blank
 or X for alive or dead, respectively * 12/15/2014: blank or X for alive or
 dead, respectively * 1/1/2015: blank or X for alive or dead, respectively
 * 1/15/2015: blank or X for alive or dead, respectively * 2/1/2015: blank
 or X for alive or dead, respectively * 2/15/2015: blank or X for alive or
 dead, respectively * 3/1/2015: blank or X for alive or dead, respectively
 * 3/15/2015: blank or X for alive or dead, respectively * 4/1/2015: blank
 or X for alive or dead, respectively * 5/1/201: blank or X for alive or
 dead, respectively * 6/1/2015: blank or X for alive or dead, respectively
 * 7/1/2015: blank or X for alive or dead, respectively *
 dead_or_alive_1July15: 0 or 1 for dead or alive, respectively, at end of
 experiment #### File: 4\_Stacy\_Ostertag\_GPS\_waypoints\_seed\_trees
 **Description:** GIS waypoints and altitudes of the 53 trees on O`ahu from
 which seeds were collected to generate seedlings. * seed_tree_ID
 (character) = lab absolute identifier for maternal tree on O`ahu from
 which seeds were collected to generate seedlings * volcano (character) =
 volcano ID on O`ahu * taxon_code (character) = eight letters representing
 eight taxa * leaf_phenotype (character) = G, P for glabrous, pubescent *
 latitude (numeric) = latitude (decimal degrees) * longitude (numeric) =
 longitude (decimal degrees) * altitude_m (numeric) = altitude of waypoint
 (meters above sea level)