An analytically derived delineation of the West African Coastal Province based on bivalves

Abstract

<h3 class="article-section__sub-title section" id="ddi13454-sec-0001-title">Aim</h3><p>To assess the pattern of biotic regions (BR) and their boundaries, to detect chorotypes and to relate these patterns to key environmental factors.</p><h3 class="article-section__sub-title section" id="ddi13454-sec-0002-title">Location</h3><p>Eastern Atlantic Ocean.</p><h3 class="article-section__sub-title section" id="ddi13454-sec-0003-title">Time period</h3><p>Recent.</p><h3 class="article-section__sub-title section" id="ddi13454-sec-0004-title">Taxon studied</h3><p>Bivalvia.</p><h3 class="article-section__sub-title section" id="ddi13454-sec-0005-title">Methods</h3><p>Distributions were scored for 595 species. Operational geographical units are classified hierarchically using Baroni-Urbani & Buser similarity index, clusters were assessed for statistical significance with the ‘RMacoqui 1.0’ software using G tests of independence, and chorotypes were inferred likewise from similarity between species distributions.</p><h3 class="article-section__sub-title section" id="ddi13454-sec-0006-title">Results</h3><p>Three strong biotic boundaries delimit four BR: (1) European Atlantic and Mediterranean; (2) West African, from western Sahara to southern Angola; (3) Baia dos Tigres/Namibia; and (4) Saint Helena/Ascension. The West African BR is subdivided by two weak boundaries into three subordinate BR: the tropical region proper, the north-western African transition zone and the cluster (southern Angola/São Tomé/Cape Verde Islands). Of the 429 species present in West Africa, 261 (60.7%) are endemic, and 19&nbsp