Genetic Diversity in Micronesian Island Populations of the Tropical Tree Campnosperma brevipetiolata (Anacardiaceae)

Sheely, Deborah L.; Meagher, Thomas R.

doi:10.2307/2445832

Cited by 11 publications

(11 citation statements)

References 20 publications

(37 reference statements)

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“… (1) Pinus canariensis (calculated from Schiller et al 1999), (2) Olea europaea subsp. guanchica (present study), (3) Atractylis preauxiana (Caujapé‐Castells et al 2008), (4) Campnosperma brevipetiolata (Sheely and Meagher 1996), (5) Rubus moluccanus (Busemeyer et al 1997), (6) Santalum austrocaledonicum (Bottin et al 2005), (7) Echium stenosiphion (Romeiras et al 2007), (8) Anagyris latifolia (González‐Pérez et al 2009), (9) Scalesia affinis (Nielsen 2004), (10) Michelia formosana (Lu et al 2002), (11) Hypericum canariense (Dlugosch and Parker 2007). …”

Section: Discussionmentioning

confidence: 73%

The Relevance of Gene Flow in Metapopulation Dynamics of an Oceanic Island Endemic, Olea Europaea Subsp. Guanchica

et al. 2010

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Theoretical and empirical studies suggest that geographical isolation and extinction-recolonization dynamics are two factors causing strong genetic structure in metapopulations, but their consequences in species with high dispersal abilities have not been tested at large scales. Here, we investigated the effect of population age structure and isolation by distance in the patterns of genetic diversity in a wind-pollinated, zoochorous tree (Olea europaea subsp. guanchica) sporadically affected by volcanic events across the Canarian archipelago. Genetic variation was assessed at six nuclear microsatellites (nDNA) and six chloroplast fragments (cpDNA) in nine subpopulations sampled on four oceanic islands. Subpopulations occurring on more recent substrates were more differentiated than those on older substrates, but within-subpopulation genetic diversity was not significantly different between age groups for any type of marker. Isolation-by-distance differentiation was observed for nDNA but not for cpDNA, in agreement with other metapopulation studies. Contrary to the general trend for island systems, between-island differentiation was extremely low, and lower than differentiation between subpopulations on the same island. The pollen-to-seed ratio was close to one, two orders of magnitude lower than the average estimated for other wind-pollinated, animal-dispersed plants.Our results showed that population turnover and geographical isolation increased genetic differentiation relative to an island model at equilibrium, but overall genetic structure was unexpectedly weak for a species distributed among islands. This empirical study shows that extensive gene flow, particularly mediated by seeds, can ameliorate population subdivision resulting from extinction-recolonization dynamics and isolation by distance.K E Y W O R D S : cpDNA, extinction-recolonization, genetic structure, island colonization, pollen-to-seed ratio, seed dispersal.Patterns of population genetic structure are shaped by synergistic effects of spatial, historical, and ecological factors. Empirical studies have largely focused on the spatial distribution of allelic frequencies, dispersal syndromes, or mating systems to explain the levels of differentiation observed in neutral markers across the range of a species (Loveless and Hamrick 1984;Petit et al. 2005). Species, however, are dynamic entities, and historical factors may also significantly contribute to patterns of genetic differentiation among populations. Thus, natural populations may experience catastrophic events, promoting local extinctions and subsequent opportunities for recolonization (Wade and Goodnight 1998). As a result, population turnover significantly modifies the constant population sizes assumed under Wright's island model (Wright 1951), and hence metapopulation dynamics provide an

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Section: Discussionmentioning

confidence: 73%

The Relevance of Gene Flow in Metapopulation Dynamics of an Oceanic Island Endemic, Olea Europaea Subsp. Guanchica

et al. 2010

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“…1995; Loiselle et al . 1995; Shapcott & Playford 1996; Sheely & Meagher 1996; Doligez & Joly 1997; Forster & Sork 1997; Makhuvha et al . 1997; Matolweni & McLellan 1997).…”

Section: Discussionmentioning

confidence: 99%

Comparison of the population genetics and densities of five Pinanga palm species at Kuala Belalong, Brunei

Shapcott

1999

Molecular Ecology

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This study investigated the effect of population density on the population genetic structure of five co-occurring congeneric understorey palm species: Pinanga aristata, P. sp. aff. brevipes, P. dumetosa, P. tenella var. tenella and P. veitchii, all endemic to northern Borneo. The average population densities of the study species varied across a wide spectrum, ranging from 343 (plants per ha) in P. tenella to 10 (plants per ha) in P. veitchii. All species of Pinanga palms studied had quite high levels of genetic diversity (HE: 0.379, 0.256, 0.294, 0.133, 0.352). Genetic diversity (HE) was correlated with population density (D; rs = - 0.433, P < 0.01) and the average distance to the nearest conspecific neighbour (NN; rs = 0.576, P < 0.001) such that the most-dense species had less genetic diversity and the less-dense species had greater genetic diversity. Gene flow (Nm) among populations approximately followed a gradient of increasing species density and abundance, such that the most common species P. dumestosa had the greatest gene flow (Nm = 2.268) between its populations and the rarest, most sparsely distributed species P. sp. aff. brevipes had the lowest (Nm = 0.698). All species of Pinanga were effectively inbred (F: 0.760, 0.856, 0.640, 0.753, 0.674). The amount of homozygosity and inbreeding (HO, F) were not correlated (P > 0.05) with population density (D) or the distance between nearest neighbouring plants of the same species (NN).

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“…Although general expectations exist on the impact of island systems on genetic diversity structuring, especially those concerning natural selection and random drift (Barton 1989), empirical evidence is still lacking to confirm or attenuate the general expected pattern on plant species. In particular, the genetic structure of forest tree species is poorly documented in fragmented habitats (Savolainen & Kuittinen 2000) and archipelagos (Sheely & Meagher 1996). However there is an increasing number of studies looking for genetic effects in other plants of recent, anthropogenic, habitat fragmentation (e.g.…”

Section: Introductionmentioning

confidence: 99%

Genetic diversity and population structure of an insular tree, Santalum austrocaledonicum in New Caledonian archipelago

et al. 2005

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We present a study of the genetic diversity and structure of a tropical tree in an insular system. Santalum austrocaledonicum is endemic to the archipelago of New Caledonia and is exploited for oil extraction from heartwood. A total of 431 individuals over 17 populations were analysed for eight polymorphic microsatellite loci. The number of alleles per locus ranged from 3 to 33 and the observed heterozygosity per population ranged from 0.01 in Maré to 0.74 in Ile des Pins. The genetic diversity was lowest in the most recent islands, the Loyautés, and highest in the oldest island, Grande Terre, as well as the nearby small Ile des Pins. Significant departures from panmixia were observed for some loci-population combinations (per population F IS = 0 -0.03 on Grande-Terre and Ile des Pins, and 0 -0.67 on Loyautés). A strong genetic differentiation among all islands was observed ( F ST = 0.22), and the amount of differentiation increased with geographic distance in Iles Loyauté and in Grande Terre. At both population and island levels, island age and isolation seem to be the main factors influencing the amount of genetic diversity. In particular, populations from recent islands had large average F IS that could not be entirely explained by null alleles or a Wahlund effect. This result suggests that, at least in some populations, selfing occurred extensively. Conclusively, our results indicate a strong influence of insularity on the genetic diversity and structure of Santalum austrocaledonicum .

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Genetic Diversity in Micronesian Island Populations of the Tropical Tree Campnosperma brevipetiolata (Anacardiaceae)

Cited by 11 publications

References 20 publications

The Relevance of Gene Flow in Metapopulation Dynamics of an Oceanic Island Endemic, Olea Europaea Subsp. Guanchica

The Relevance of Gene Flow in Metapopulation Dynamics of an Oceanic Island Endemic, Olea Europaea Subsp. Guanchica

Comparison of the population genetics and densities of five Pinanga palm species at Kuala Belalong, Brunei

Genetic diversity and population structure of an insular tree, Santalum austrocaledonicum in New Caledonian archipelago

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