DOI: 10.5061/dryad.gm2v0
title: Data from: Seascape drivers of Macrocystis pyrifera population genetic structure in the northeast Pacific

description: At small spatial and temporal scales, genetic differentiation is largely
 controlled by constraints on gene flow, while genetic diversity across a
 species' distribution is shaped on longer temporal and spatial
 scales. We assess the hypothesis that oceanographic transport and other
 seascape features explain different scales of genetic structure of giant
 kelp, Macrocystis pyrifera. We followed a hierarchical approach to perform
 a microsatellite-based analysis of genetic differentiation in Macrocystis
 across its distribution in the northeast Pacific. We used seascape genetic
 approaches to identify large-scale biogeographic population clusters and
 investigate whether they could be explained by oceanographic transport and
 other environmental drivers. We then modelled population genetic
 differentiation within clusters as a function of oceanographic transport
 and other environmental factors. Five geographic clusters were identified:
 Alaska/Canada, central California, continental Santa Barbara, California
 Channel Islands and mainland southern California/Baja California
 peninsula. The strongest break occurred between central and southern
 California, with mainland Santa Barbara sites forming a transition zone
 between the two. Breaks between clusters corresponded approximately to
 previously identified biogeographic breaks, but were not solely explained
 by oceanographic transport. An isolation-by-environment (IBE) pattern was
 observed where the northern and southern Channel Islands clustered
 together, but not with closer mainland sites, despite the greater distance
 between them. The strongest environmental association with this IBE
 pattern was observed with light extinction coefficient, which extends
 suitable habitat to deeper areas. Within clusters, we found support for
 previous results showing that oceanographic connectivity plays an
 important role in the population genetic structure of Macrocystis in the
 Northern hemisphere.
description: Genotype Data_Structure
 formatComplete genotype data
 in Structure program format. Row 1 lists the microsatellite markers.
 Microsatellite data are presented in two-column per marker format. Missing
 data are indicated with -9. Column 1 gives the population and sample
 identifier, column 2 gives the population number, remaining columns are
 microsatellite data.Allelic Richness
 Code_standarichR script for calculating
 standardized allelic richness using R package
 "standarich"Allelic Richness
 DataData file for
 calculating standardized allelic richness using R package
 "standarich"CCA
 ScriptR script for performing
 canonical correspondence analysis for environmental data and Structure
 cluster membershipCCA
 DataData file for use with
 the CCA script for performing canonical correspondence analysis for
 environmental data and Structure cluster membership in
 RHabitat Network
 ScriptR script for performing
 network analysis for summer transport time using R package
 "igraph"Habitat
 Network_OceanDistanceMatricesMatrix of ocean
 transport distances for use with the Habitat Network
 ScriptHabitat
 Network_site_centersLocation data for use
 with the Habitat Network ScriptLinear Models
 DataPairwise data for use
 with Linear Model R scripts. Includes comparison pair, Population In ID,
 Population Out ID, Groups to which Populations belong (SCA=Southern
 California, SBC=Santa Barbara Channel Mainland, CCA=Central California),
 Pairwise linearized FST (FST/1-FST), Distance between sites, Area of
 habitat between sites, Habitat area per km between sites, Summer and
 Winter mean temperature difference between sites, Summer and Winter mean
 maximum significant wave height, transport time (5km model), Annual,
 Seasonal, and Monthly minimum mean transport time between sites, and
 biomass correlation between sites using a 500m, 1000m, and 2000m buffer
 area around each site.Linear Models - Central
 CaliforniaR script used to perform
 linear model selection for Central California
 populationsLinear Models - Santa
 Barbara ChannelR script used to perform
 linear model selection for Santa Barbara Channel mainland
 populationsLinear Models - Southern
 CaliforniaR script used to perform
 linear model selection for Southern California
 populationsGenetic Network Script -
 gtx2networkR script to construct a
 network based on Cavalli-Sforza chord distance between
 populations