Disentangling the historical routes to community assembly in the global epicentre of biodiversity

<p><strong>Aim:</strong> The exceptional turnover in biota with elevation and number of species coexisting at any elevation makes tropical mountains hotspots of biodiversity. However, understanding the historical processes through which species arising in geographical isolation (i....

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Main Authors: Reijenga, BR, Freeman, BG, Murrell, DJ, Pigot, AL
Format: Journal article
Language:English
Published: Wiley 2023
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author Reijenga, BR
Freeman, BG
Murrell, DJ
Pigot, AL
author_facet Reijenga, BR
Freeman, BG
Murrell, DJ
Pigot, AL
author_sort Reijenga, BR
collection OXFORD
description <p><strong>Aim:</strong> The exceptional turnover in biota with elevation and number of species coexisting at any elevation makes tropical mountains hotspots of biodiversity. However, understanding the historical processes through which species arising in geographical isolation (i.e. allopatry) assemble along the same mountain slope (i.e. sympatry) remains a major challenge. Multiple models have been proposed including (1) the sorting of already elevationally divergent species, (2) the displacement of elevation upon secondary contact, potentially followed by convergence, or (3) elevational conservatism, in which ancestral elevational ranges are retained. However, the relative contribution of these processes to generating patterns of elevational overlap and turnover is unknown.</p> <p><strong>Location:</strong> Tropical mountains of Central- and South-America.</p> <p><strong>Time Period:</strong> The last 12 myr.</p> <p><strong>Major Taxa Studied:</strong> Birds.</p> <p><strong>Methods:</strong> We collate a dataset of 165 avian sister pairs containing estimates of phylogenetic age, geographical and regional elevational range overlap. We develop a framework based on continuous-time Markov models to infer the relative frequency of different historical pathways in explaining present-day overlap and turnover of sympatric species along elevational gradients.</p> <p><strong>Results:</strong> We show that turnover of closely related bird species across elevation can predominantly be explained by displacement of elevation ranges upon contact (81%) rather than elevational divergence in allopatry (19%). In contrast, overlap along elevation gradients is primarily (88%) explained by conservatism of elevational ranges rather than displacement followed by elevational expansion (12%).</p> <p><strong>Main Conclusions:</strong> Bird communities across elevation gradients are assembled through a mix of processes, including the sorting, displacement and conservatism of species elevation ranges. The dominant role of conservatism in explaining co-occurrence of species on mountain slopes rejects more complex scenarios requiring displacement followed by expansion. The ability of closely related species to coexist without elevational divergence provides a direct and faster pathway to sympatry and helps explain the exceptional species richness of tropical mountains.</p>
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spelling oxford-uuid:ced932f5-3639-46eb-8de4-fa45e0ecaab02023-10-03T15:22:19ZDisentangling the historical routes to community assembly in the global epicentre of biodiversityJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:ced932f5-3639-46eb-8de4-fa45e0ecaab0EnglishSymplectic ElementsWiley2023Reijenga, BRFreeman, BGMurrell, DJPigot, AL<p><strong>Aim:</strong> The exceptional turnover in biota with elevation and number of species coexisting at any elevation makes tropical mountains hotspots of biodiversity. However, understanding the historical processes through which species arising in geographical isolation (i.e. allopatry) assemble along the same mountain slope (i.e. sympatry) remains a major challenge. Multiple models have been proposed including (1) the sorting of already elevationally divergent species, (2) the displacement of elevation upon secondary contact, potentially followed by convergence, or (3) elevational conservatism, in which ancestral elevational ranges are retained. However, the relative contribution of these processes to generating patterns of elevational overlap and turnover is unknown.</p> <p><strong>Location:</strong> Tropical mountains of Central- and South-America.</p> <p><strong>Time Period:</strong> The last 12 myr.</p> <p><strong>Major Taxa Studied:</strong> Birds.</p> <p><strong>Methods:</strong> We collate a dataset of 165 avian sister pairs containing estimates of phylogenetic age, geographical and regional elevational range overlap. We develop a framework based on continuous-time Markov models to infer the relative frequency of different historical pathways in explaining present-day overlap and turnover of sympatric species along elevational gradients.</p> <p><strong>Results:</strong> We show that turnover of closely related bird species across elevation can predominantly be explained by displacement of elevation ranges upon contact (81%) rather than elevational divergence in allopatry (19%). In contrast, overlap along elevation gradients is primarily (88%) explained by conservatism of elevational ranges rather than displacement followed by elevational expansion (12%).</p> <p><strong>Main Conclusions:</strong> Bird communities across elevation gradients are assembled through a mix of processes, including the sorting, displacement and conservatism of species elevation ranges. The dominant role of conservatism in explaining co-occurrence of species on mountain slopes rejects more complex scenarios requiring displacement followed by expansion. The ability of closely related species to coexist without elevational divergence provides a direct and faster pathway to sympatry and helps explain the exceptional species richness of tropical mountains.</p>
spellingShingle Reijenga, BR
Freeman, BG
Murrell, DJ
Pigot, AL
Disentangling the historical routes to community assembly in the global epicentre of biodiversity
title Disentangling the historical routes to community assembly in the global epicentre of biodiversity
title_full Disentangling the historical routes to community assembly in the global epicentre of biodiversity
title_fullStr Disentangling the historical routes to community assembly in the global epicentre of biodiversity
title_full_unstemmed Disentangling the historical routes to community assembly in the global epicentre of biodiversity
title_short Disentangling the historical routes to community assembly in the global epicentre of biodiversity
title_sort disentangling the historical routes to community assembly in the global epicentre of biodiversity
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