Patterns of biodiversity and endemism on Indo-West Pacific coral reefs

Abstract

Diversity of the primary groups of contemporary Indo-West Pacific coral reef organisms, including mantis shrimps (stomatopod crustaceans), peaks in the Indo-Australian Archipelago (IAA), reaches a lower peak in East Africa and Madagascar [Indian Ocean continental (IOC)], and declines in the central Indian Ocean (IO) and Central Pacific (CP). Percent endemism in stomatopods (highest in the IAA, high in the IOC, lower in regions adjacent to centers, and moderate in the CP) correlates positively with species diversity (this varies with scale) and inversely with species body size. Because it constrains reproductive traits and dispersal, body size is a reliable indicator of speciation and extinction potential in reef stomatopods and probably most marine organisms. Assemblages are dominated by small-sized species in the IAA and IOC. Both speciation and extinction likely are high, resulting in especially high endemism (small ranges reflect both originating and disappearing species) in these regions. Rates of speciation exceed extinction, yielding centers of diversity (especially in the IAA). Dispersal slows speciation and extinction in areas adjacent to these centers. Body size declines toward the CP, especially in atoll environments. Here the wheels of speciation and extinction again spin rapidly but in the opposite direction (extinction > speciation), yielding low diversity and moderate endemism. We conclude that life histories, dispersal, and speciation/extinction dynamics are primary agents that mold patterns of diversity and endemism. Historical factors, currents, productivity, and species diversity itself (through ecological interactions) also influence these patterns, in some cases by altering body size.hot spots ͉ stomatopod ͉ life history ͉ geographic range ͉ body size B eing repositories of ancient phyla as well as more recent specialized taxa, coral reefs are among the most spectacular, productive, diverse (per unit area), and threatened ecosystems on earth. Organisms they house provide a critical source of protein for people in many tropical countries, and reefs themselves protect human populations from storm and wave damage. Coral reefs provide aesthetic beauty (and the bioeroded sand on beaches) for tourism-an increasingly important economic resource for developing tropical countries. However, tourism and other uses of reefs must be carefully managed to be of sustainable economic benefit. A fundamental value of coral reefs is that they provide an aesthetic, intellectual, educational, and cultural heritage for present and future generations.Threats to global coral reefs, however, are severe and well documented (1-9). Overexploitation has been identified as an especially serious problem, but other threats include coastal development and sedimentation, pollution, global warming, disease, and ocean acidification. The Global Coral Reef Monitoring Network reports that 20% of global coral reefs already have been degraded beyond recovery, an additional 24% are under imminent threat of collapse, and a further 26% ...

Royseux: a palaeobiodiversity hotspot in the Late Viséan (Carboniferous) of Belgium

“…However, taxic diversity and endemism are commonly decoupled. Centres of endemism mostly occur on the periphery of hotspots (Reaka & Lombardi, 2011;Reaka et al, 2008). This would be consistent with hotspot diversity resulting from the accumulation of taxa through time (Bellwood et al, 2012).…”

Inshore Fishes of Howland Island, Baker Island, Jarvis Island, Palmyra Atoll, and Kingman Reef

“…Peripheral isolation has been proposed, as the centripetal or vortex model of biogeography (Jokiel and Martinelli, 1992), as a general alternative to the center of origin or centrifugal model for Indo-Pacific biogeography (Briggs, 2000). Neither generalized model is supported by the diversity of origins in phylogenetic and phylogeographic analyses of shore fishes discussed in the previous sections on phylogeography, phylogenetic analysis, and geologic history, nor for other Indo-Pacific organisms (Reaka et al, 2008). , Apogon lativittatus, and Chaetodon declivis, with subspecies recognized for the Marquesan (C. declivis declivis) and Line Islands populations (C. declivis wilderi) (see Randall, 2001a).…”

In the Light of Evolution II: Biodiversity and Extinction

“…Approximately 70% of coral reefs globally have been degraded beyond recognition in recent years (20%), are in imminent danger of collapse (24%), or are under longer-term threat of demise (26%) (8). Marjorie Reaka et al (9) survey reef-dwelling stomatopods (a large group of marine crustaceans) as a model taxon to assess global hotspots of extant biodiversity, endemism, and extinction risk, the intent being to identify evolutionary sources and sinks of stomatopod diversity, infer driving mechanisms, and provide an additional focus for conservation and management efforts on coral reefs. Stomatopod species diversity (like that of several other reef-dwelling marine taxa) is highest in the Indo-Australian Archipelago, gradually declines eastward across the central Pacific, and shows a secondary peak of species richness in the southwestern Indian Ocean.…”