DOI: 10.5061/dryad.vhhmgqnsh
title: Intraspecific genetic variation matters when predicting seagrass distribution under climate change

description: Seagrasses play a vital role in structuring coastal marine ecosystems, but
 their distributional range and genetic diversity have declined rapidly
 over the past decades. In order to improve conservation of seagrass
 species, it is important to predict how climate change may impact their
 ranges. Such predictions are typically made with correlative species
 distribution models (SDMs), which can estimate a species’ potential
 distribution under present and future climatic scenarios given species’
 presence data and climatic predictor variables. However, these models are
 typically constructed with species-level data, and thus ignore
 intraspecific genetic variability, which can give rise to populations with
 adaptations to heterogeneous climatic conditions. Here, we explore the
 link between intraspecific adaptation and niche differentiation in
 Thalassia hemprichii, a seagrass broadly distributed in the tropical
 Indo-Pacific Ocean and a crucial provider of habitat for numerous marine
 species. Using microsatellite-based genotyping, we identified two distinct
 phylogeographical lineages within the nominal species and found an
 intermediate level of differentiation in their multidimensional
 environmental niches, suggesting the possibility for local adaptation. We
 then compared projections of the species’ habitat suitability under
 climate change scenarios using species-level and lineage-level SDMs. In
 the Central Tropical Indo-Pacific region, models for both levels predicted
 considerable range contraction in the future, but the lineage-level models
 predicted more severe habitat loss. Importantly, the two modelling
 approaches predicted opposite patterns of habitat change in the Western
 Tropical Indo-Pacific region. Our results highlight the necessity of
 conserving distinct populations and genetic pools to avoid regional
 extinction due to climate change and have important implications for
 guiding future management of seagrasses.
description: Microsatellite dataset was collected from two previously
 published papers (Hernawan <i>et al.</i> 2017; Jahnke
 <i>et al.</i> 2019), and they were compiled and reused for
 phylogeographic analysis. Species occurence records for species
 distribution modelling were obtained by searching literatures and public
 database. Hernawan, U., van Dijk K., Kendrick, G.,
 Feng, M., Biffin, E., … & McMahon, K. (2017). Historical processes
 and contemporary ocean currents drive genetic structure in the seagrass
 <i>Thalassia hemprichii</i> in the Indo-Australian
 Archipelago. Molecular Ecology, 26, 1008–1021. Jahnke,
 M., Gullström, M., Larsson, J., Asplund, M. E., Mgeleka, S., Silas, M. O.,
 … & Nordlund, L. M. (2019). Population genetic structure and
 connectivity of the seagrass <i>Thalassia hemprichii</i> in
 the Western Indian Ocean is influenced by predominant ocean currents.
 Ecology and Evolution, 9, 8953–8964.
description: The readme file contains a detailed explanation of each file
 uploaded for phylogeographic analysis and SDM projections at both species
 and lineage levels, respectively.