Genetic diversity, distributional barriers and rafting continents - more thoughts on the evolution of mangroves

Duke, Norman C. (1995) Genetic diversity, distributional barriers and rafting continents - more thoughts on the evolution of mangroves. Hydrobiologia, 295 (1). pp. 167-181.

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Without continental drift, the diversity and distribution of many species, including mangrove plants, would be very different today. First, there would be fewer pantropic genera and many more endemics. Second, their characteristics would not be as common and widespread as some are today. Continental drift has brought about the massive mixing and dispersal of genes in geologically recent times, greatly enhancing the evolutionary process; particularly for flowering plants - the angiosperms, which evolved during this period. Mangrove plants are comprised of approximately 70 species from 20 quite different angiosperm families. Most taxa are characterized by special physiological abilities and structural forms, enabling them to live in both seasonally fluctuating saline conditions, and water-saturated soils. Their occurrence is mostly tropical, perhaps because of harsh physiological conditions of intertidal habitats; but distributions of specific taxa do not fully concur with the idea of a completely tropical evolution, at least for some important species. At least one genus of mangrove tree, Avicennia, occurs around the world, chiefly in tropical estuarine habitats, although they also range into temperate latitudes, especially in the south. Around the world, there are no more than ten species of Avicennia recognised today, but their diagnostic determinants were inadequate prior to recent studies using both numerical analyses of morphological parameters and isozymes. Such analyses significantly reduced the number of apparent species, notably around Australia, and provided a basis for the revision of distributional records throughout the Indo West Pacific region. One species, A. marina, was found to be widespread and morphologically variable with genes divided into characteristic groupings of at least three geographic areas in the region. Based on these findings, there are several novel inferences to be made regarding the evolution of this genus. A western Gondwanan origin is proposed, with subsequent radiation of several taxa facilitated via the tectonic dispersal of southern continental fragments.

Item ID: 48902
Item Type: Article (Research - C1)
ISSN: 1573-5117
Keywords: mangrove; plants; Avicennia; biogeography; evolution; distribution; world
Date Deposited: 11 May 2017 23:00
FoR Codes: 05 ENVIRONMENTAL SCIENCES > 0502 Environmental Science and Management > 050202 Conservation and Biodiversity @ 30%
06 BIOLOGICAL SCIENCES > 0603 Evolutionary Biology > 060302 Biogeography and Phylogeography @ 40%
06 BIOLOGICAL SCIENCES > 0602 Ecology > 060205 Marine and Estuarine Ecology (incl Marine Ichthyology) @ 30%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970106 Expanding Knowledge in the Biological Sciences @ 30%
96 ENVIRONMENT > 9605 Ecosystem Assessment and Management > 960503 Ecosystem Assessment and Management of Coastal and Estuarine Environments @ 30%
96 ENVIRONMENT > 9608 Flora, Fauna and Biodiversity > 960802 Coastal and Estuarine Flora, Fauna and Biodiversity @ 40%
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