Evidence of Late Palaeocene-Early Eocene equatorial rain forest refugia in southern Western Ghats, India

Prasad, Vandana; Farooqui, Anjum; Tripathi, Swati; Garg, Rahul; Thakur, Biswajeet

doi:10.1007/s12038-009-0062-y

Cited by 114 publications

(103 citation statements)

References 27 publications

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“…Their fossil wood and pollen reveals a southern retreat of an already rich rain forest tree flora, similar to that of the modern hyper-diverse Sunda mixed dipterocarp forest, which is now confined in South Asia to a tiny, 10,000 km 2 patch in SW Sri Lanka, which itself must anticipate a final demise over future geological time (Ashton, 2014;Conti et al, 2002;Morley, 2000;Prasad et al, 2009, Rust et al , 2010 (Figure 1). …”

Section: Introductionmentioning

confidence: 90%

“…The existence of such refugia could play an important role in accumulating and preserving vital signatures of ancient lineages which have contributed to present day species diversity through range shifts/expansions via episodic corridors (Antonelli et al, 2010;Ashton, 2014;Prasad et al, 2009). Consequently, such refugial hotspots of biological diversity are indeed among the best laboratories for identification of and analysis for conservation through prioritized phylogeographic research (Couvreur et al, 2008, Joshi andKaranth, 2013).…”

Section: Sw Sri Lanka As a Floristic Refugiummentioning

confidence: 99%

“…However, relatively little is known about the evolutionary processes that have led to the generation of these hyper-rich ecosystems and their phylogenetic diversity. This extraordinary diversity can best be explained by understanding their evolutionary history in relation to the land and climatic history and the accompanying biogeographic processes (Datta-Roy and Karanth, 2009;Prasad et al, 2009). …”

Section: Sw Sri Lanka As a Floristic Refugiummentioning

confidence: 99%

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South-west Sri Lanka: a floristic refugium in South Asia

Gunatilleke

Ashton³

2017

Ceylon J. Sci.

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Abstract:In South Asia, south-west Sri Lanka alone represents the sole surviving perhumid region where Mixed Dipterocarp Forests (MDF) harbour a number of relict signature taxa providing evidence of ancient plant migration routes from Gondwana to perhumid Far Eastern Sunda land, at least partially via southern Laurasia. Palynological and phylogenetic evidence now confirm that the Malesian rain forest flora overwhelmingly immigrated from tropical Africa/Madagascar and South Asia along an everwet equatorial corridor sometime before the collision of the Indian Plate with the Southern Laurasian coast in middle Eocene (c. 45 Ma). This ever-wet climatic and geological history has led to the evolution of a characteristic species composition and dynamics within SW Sri Lanka's rain forest communities, which exhibit remarkable patterns of species distribution and habitat specialization, and which parallel those of Far Eastern sister taxa.We here examine the patterns of floristic variation in each of three MDF sites using classification and ordination methods to analyse tree data collected in 62 random plots, each 0.25ha, along an altitudinal gradient. In addition, a 25 ha forest dynamics plot (FDP) was established in the Sinharaja World Heritage Site, within the CTFS-ForestGEO network that addresses issues related to community ecology and phylogenetics incorporating large-scale biogeographic patterns of major clades of both plants and animals.In the above studies, ecologically distinct floristic assemblages were revealed, i) among the three MDF sites as well as, ii) among the ridge-, slope-, and valley habitats within each forest site. In the FDP too, >80% of the 125 species, with individuals >1 cm dbh and >100 individuals per species, are significantly more associated with one or more of eight topographic habitat categories than in others. These results suggest that ecological ranges and dispersion of tree species in SW Sri Lanka is primarily mediated by soil water and nutrient levels in topographically different catenal habitats mirroring those in the Far East.Many of these species are threatened relict endemics, and their distribution patterns have important conservation implications. Their spatial distributional features provide useful criteria in sitespecies matching or environmental filtering in forest restoration efforts.

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Section: Introductionmentioning

confidence: 90%

Section: Sw Sri Lanka As a Floristic Refugiummentioning

confidence: 99%

Section: Sw Sri Lanka As a Floristic Refugiummentioning

confidence: 99%

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South-west Sri Lanka: a floristic refugium in South Asia

Gunatilleke

Ashton³

2017

Ceylon J. Sci.

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“…The sister lineages in the lowlands have persisted without further opportunities for speciation, while the high elevation ancestral lineages have diversified into multiple allopatric lineages owing to geographical isolation (figure 5). The persistence of a historical rainforest refugium in the southern Western Ghats [50] could have played a significant role in promoting persistence, reducing extinction, and range expansion of these lineages at low and medium elevations. forest-grassland dynamics associated with glacial and interglacial periods within these massifs [14].…”

Section: (B) Sisters On Adjacent Massifs: Quaternary Glaciations Versmentioning

confidence: 99%

Glaciations, gradients, and geography: multiple drivers of diversification of bush frogs in the Western Ghats Escarpment

et al. 2016

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The historical processes underlying high diversity in tropical biodiversity hotspots like the Western Ghats of Peninsular India remain poorly understood. We sampled bush frogs on 13 massifs across the Western Ghats Escarpment and examined the relative influence of Quaternary glaciations, ecological gradients and geological processes on the spatial patterns of lineage and clade diversification. The results reveal a large in situ radiation (more than 60 lineages), exhibiting geographical structure and clade-level endemism, with two deeply divergent sister clades, North and South, highlighting the biogeographic significance of an ancient valley, the Palghat Gap. A majority of the bush frog sister lineages were isolated on adjacent massifs, and signatures of range stasis provide support for the dominance of geological processes in allopatric speciation. In situ diversification events within the montane zones (more than 1800 m) of the two highest massifs suggest a role for climate-mediated forest-grassland persistence. Independent transitions along elevational gradients among sub-clades during the Miocene point to diversification along the elevational gradient. The study highlights the evolutionary significance of massifs in the Western Ghats with the high elevations acting as centres of lineage diversification and the low-and mid-elevations of the southern regions, with deeply divergent lineages, serving as museums.

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“…However, it is not clear if Triops could have survived a phase of tropical humid climate in the early Eocene occurring throughout India (see climatic reconstructions in Scotese, 2012), prior to India's collision with Asia. At that time, tropical rainforests were widely distributed in India (Prasad et al, 2009), so that habitats suitable for Notostraca might have been scarse or even completely absent from India. Continuing evolution of the 'T.…”

Section: Biogeography Of the Genus Triopsmentioning

confidence: 99%

Molecular phylogeny of the Notostraca

Korn

Rabet

Ghate³

et al. 2013

Molecular Phylogenetics and Evolution

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a b s t r a c tWe used a combined analysis of one nuclear (28S rDNA) and three mitochondrial markers (COI, 12S rDNA, 16S rDNA) to infer the molecular phylogeny of the Notostraca, represented by samples from the six continents that are inhabited by this group of branchiopod crustaceans. Our results confirm the monophyly of both extant notostracan genera Triops and Lepidurus with good support in model based and maximum parsimony analyses. We used branchiopod fossils as a calibration to infer divergence times among notostracan lineages and accounted for rate heterogeneity among lineages by applying relaxed-clock models. Our divergence date estimates indicate an initial diversification into the genera Triops and Lepidurus in the Mesozoic, most likely at a minimum age of 152.3-233.5 Ma, i.e., in the Triassic or Jurassic. Implications for the interpretation of fossils and the evolution of notostracan morphology are discussed. We further use the divergence date estimates to formulate a biogeographic hypothesis that explains distributions of extant lineages predominantly by overland dispersal routes. We identified an additional hitherto unrecognised highly diverged lineage within Lepidurus apus lubbocki and three additional previously unknown major lineages within Triops. Within T. granarius we found deep differentiation, with representatives distributed among three major phylogenetic lineages. One of these major lineages comprises T. cancriformis, the T. mauritanicus species group and two hitherto unrecognised T. granarius lineages. Samples that were morphologically identified as T. granarius diverged from the most basal nodes within this major lineage, and divergence dates suggested an approximate age of 23.7-49.6 Ma for T. cancriformis, indicating the need for a taxonomic revision of Triassic and Permian fossils that are currently attributed to the extant T. cancriformis. We thus elevate T. cancriformis minor to full species status as Triops minor Trusheim, 1938 and include in this species the additional Upper Triassic samples that were attributed to T. cancriformis. We further elevate T. cancriformis permiensis to full species status as Triops permiensis Gand et al., 1997.

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Evidence of Late Palaeocene-Early Eocene equatorial rain forest refugia in southern Western Ghats, India

Cited by 114 publications

References 27 publications

South-west Sri Lanka: a floristic refugium in South Asia

South-west Sri Lanka: a floristic refugium in South Asia

Glaciations, gradients, and geography: multiple drivers of diversification of bush frogs in the Western Ghats Escarpment

Molecular phylogeny of the Notostraca

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