Evolutionary contingency in lingulid brachiopods across mass extinctions

• Published in: Current biology Vol. 33; no. 8; pp. 1565 - 1572.e3
• Main Authors: Liang, Yue, Strotz, Luke C., Topper, Timothy P., Holmer, Lars E., Budd, Graham E., Chen, Yanlong, Fang, Ruisen, Hu, Yazhou, Zhang, Zhifei
• Format: Journal Article
• Language: English
• Published: England Elsevier Inc 24.04.2023
• Subjects: Animals; Biodiversity; Biological Evolution; brachiopods; contingency; Diversity of life; Earth Science with specialization in Historical Geology and Palaeontology; Ecosystem; Extinction, Biological; Fossils; Geovetenskap med inriktning mot historisk geologi och paleontologi; Invertebrates - genetics; Livets mångfald; macroevolution; mass extinctions; morphospace; macroevolution; contingency; mass extinctions; brachiopods; morphospace
• ISSN: 0960-9822; 1879-0445; 1879-0445
• DOI: 10.1016/j.cub.2023.02.038

Morphology usually serves as an effective proxy for functional ecology,1,2,3,4,5 and evaluating morphological, anatomical, and ecological changes permits a deeper understanding of the nature of diversification and macroevolution.5,6,7,8,9,10,11,12 Lingulid (order Lingulida) brachiopods are both diverse and abundant during the early Palaeozoic but decrease in diversity over time, with only a few genera of linguloids and discinoids present in modern marine ecosystems, resulting in them frequently being referred to as “living fossils.”13,14,15 The dynamics that drove this decline remain uncertain, and it has not been determined if there is an associated decline in morphological and ecological diversity. Here, we apply geometric morphometrics to reconstruct global morphospace occupation for lingulid brachiopods through the Phanerozoic, with results showing that maximum morphospace occupation was reached by the Early Ordovician. At this time of peak diversity, linguloids with a sub-rectangular shell shape already possessed several evolutionary features, such as the rearrangement of mantle canals and reduction of the pseudointerarea, common to all modern infaunal forms. The end Ordovician mass extinction has a differential effect on linguloids, disproportionally wiping out those forms with a rounded shell shape, while forms with sub-rectangular shells survived both the end Ordovician and the Permian-Triassic mass extinctions, leaving a fauna predominantly composed of infaunal forms. For discinoids, both morphospace occupation and epibenthic life strategies remain consistent through the Phanerozoic. Morphospace occupation over time, when considered using anatomical and ecological analyses, suggests that the limited morphological and ecological diversity of modern lingulid brachiopods reflects evolutionary contingency rather than deterministic processes. •Morphospace occupation of lingulid brachiopods through the Phanerozoic•Maximum morphospace occupation was achieved by the Early Ordovician•End Ordovician and Permian mass extinctions impacted morphological diversity•The shift to infaunal forms likely reflects historical contingency events Liang et al. analyze the global morphospace occupation of lingulid brachiopods through the Phanerozoic. Detailed examination of lingulid morphology suggests that the limited morphological and ecological diversity of modern lingulids likely reflects disproportionate winnowing of morphospace occupation and ecological disparity due to extinction.