DOI: 10.5061/dryad.ncjsxkt6p
title: Data from: Ancestral state reconstruction sheds new light on the loss of divarication hypothesis on New Zealand’s outlying islands

description: The New Zealand flora is remarkable in many respects, but one of its most
 notable features is the convergent evolution of many plant lineages toward
 a divaricate habit. The adaptive significance of divarication remains
 controversial, but it has usually been considered a response to harsh
 climates or a defence mechanism against the diverse array of Ratites
 (large browsing birds) that once populated New Zealand. The loss of
 divarication hypothesis posits that divaricate-related traits should be
 lost on New Zealand’s outlying islands, as these islands were never
 reached by Ratites. Like most evolutionary components of the island
 syndrome, this hypothesis was tested through the pairwise comparison
 method, i.e. by comparing traits of island endemics to those of their
 closest relative(s) on the mainland, assuming that the most recent common
 ancestor (MRCA) was divaricate. This assumption was challenged by recent
 results but has never been tested. Here, we test this
 assumption. We collated data for all but one genus comprising at
 least one divaricate species and one island endemic in the New Zealand
 region. We used ancestral range reconstruction to determine which endemics
 colonized the islands from New Zealand. We then used ancestral state
 reconstruction to test whether each MRCA was divaricate and to quantify
 the degree of morphological evolution in leaf size and branching angle
 (i.e. significant divaricate traits) on islands. 21 out of 29
 MRCAs were estimated as most likely non-divaricate, meaning that in most
 cases divarication evolved on the mainland and was never present on New
 Zealand’s outlying islands. Island endemics also evolved larger leaves and
 smaller branching angles regardless of whether the MRCA was divaricate or
 not. Synthesis. These findings show how most island lineages were never
 divaricate, and advance our understanding of the evolution of divarication
 in the New Zealand region. In addition, they have broader implications for
 the field of island biogeography, as they highlight the limits of the
 pairwise comparison method and provide a way to overcome them.
description: # Ancestral state reconstruction sheds new light on the loss of
 divarication hypothesis on New Zealand’s outlying islands
 [https://doi.org/10.5061/dryad.ncjsxkt6p](https://doi.org/10.5061/dryad.ncjsxkt6p) ## Description of the data and file structure Data collected and supplemental information produced to test the loss of divarication hypothesis on New Zealand's outlying islands ### Data and supplemental information #### File: Supplementary\_1\_Supplemental\_information.docx **Description:** Supplementary figures and Trees showing the results of ancestral area reconstruction #### File: Supplementary\_2\_Data.xlsx **Description:** Data used for the analysis. Species list and traits data, along with a list of herbarium specimens from which the traits were measured. Trait data could not be obtained for species absent from the herbaria. Missing values are indicated with n/a #### File: Supplementary\_3\_Supplementary\_tables.csv **Description:** Supplementary tables ##### Variables present in supplementary 2 * Divaricate habit: whether a species is divaricate or not * Insular endemics: which species are endemic to one of New Zealand's outlying islands * Leaf size: average leaf area measured in mm2 * Branching angle: average branching angle measured in decimal degrees