Population genetic suggestions to offset the extinction ratchet in the endangered Canarian endemic Atractylis preauxiana (Asteraceae)

Caujapé‐Castells, Juli; Naranjo-Suárez, José; Santana, Isabel; Baccarani-Rosas, Mario; Cabrera-García, Nereida; Marrero, M.; Carqué, Eduardo; Mesa, Ricardo

doi:10.1007/s00606-008-0020-4

Cited by 11 publications

(3 citation statements)

References 28 publications

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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: 72%

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: 72%

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

et al. 2010

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“…The TRANSFORMER-3 program [ 54 ] was used to generate the input files for the software packages used. Within each population, the analyses were performed at the genet level (i.e., excluding those individuals that presented significantly low probability (P < 0.05) of having a sexual origin).…”

Section: Methodsmentioning

confidence: 99%

Population genetics at three spatial scales of a rare sponge living in fragmented habitats

Blanquer

Uriz

2010

BMC Evol Biol

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BackgroundRare species have seldom been studied in marine habitats, mainly because it is difficult to formally assess the status of rare species, especially in patchy benthic organisms, for which samplings are often assumed to be incomplete and, thus, inappropriate for establishing the real abundance of the species. However, many marine benthic invertebrates can be considered rare, due to the fragmentation and rarity of suitable habitats. Consequently, studies on the genetic connectivity of rare species in fragmented habitats are basic for assessing their risk of extinction, especially in the context of increased habitat fragmentation by human activities. Sponges are suitable models for studying the intra- and inter-population genetic variation of rare invertebrates, as they produce lecitotrophic larvae and are often found in fragmented habitats.ResultsWe investigated the genetic structure of a Mediterranean sponge, Scopalina lophyropoda (Schmidt), using the allelic size variation of seven specific microsatellite loci. The species can be classified as "rare" because of its strict habitat requirements, the low number of individuals per population, and the relatively small size of its distribution range. It also presents a strong patchy distribution, philopatric larval dispersal, and both sexual and asexual reproduction. Classical genetic-variance-based methods (AMOVA) and differentiation statistics revealed that the genetic diversity of S. lophyropoda was structured at the three spatial scales studied: within populations, between populations of a geographic region, and between isolated geographic regions, although some stochastic gene flow might occur among populations within a region. The genetic structure followed an isolation-by-distance pattern according to the Mantel test. However, despite philopatric larval dispersal and fission events in the species, no single population showed inbreeding, and the contribution of clonality to the population makeup was minor (only ca. 4%).ConclusionsThe structure of the S. lophyropoda populations at all spatial scales examined confirms the philopatric larval dispersal that has been reported. Asexual reproduction does not seem to play a relevant role in the populations. The heterozygote excess and the lack of inbreeding could be interpreted as a hitherto unknown outcrossing strategy of the species. The envisaged causes for this strategy are sperm dispersal, a strong selection against the mating of genetically related individuals to avoid inbreeding depression or high longevity of genets combined with stochastic recruitment events by larvae from other populations. It should be investigated whether this strategy could also explain the genetic diversity of many other patchy marine invertebrates whose populations remain healthy over time, despite their apparent rarity.

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“…The low overall genetic diversities compared to other endemic species on older islands of the Canaries support this idea, see, for example, Atractylis preauxiana on Gran Canaria ( H t = 0.219) and Tenerife ( H t = 0.229) (Caujapé‐Castells et al. ), Gnaphalium teydeum on Tenerife ( H t = 0.173) (González‐Pérez et al. ), both studies performed with RAPD analyses; or Solanum vespertilio on Tenerife ( H t = 0.205) and Solanum lidii on Gran Canaria ( H t = 0.207) observed with AFLP data (Prohens et al.…”

Section: Discussionmentioning

confidence: 97%

Spatial and ecological population genetic structures within two island‐endemic Aeonium species of different niche width

Harter

Thiv

Weig

et al. 2015

Ecology and Evolution

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The Crassulacean genus Aeonium is a well‐known example for plant species radiation on oceanic archipelagos. However, while allopatric speciation among islands is documented for this genus, the role of intra‐island speciation due to population divergence by topographical isolation or ecological heterogeneity has not yet been addressed. The aim of this study was to investigate intraspecific genetic structures and to identify spatial and ecological drivers of genetic population differentiation on the island scale. We analyzed inter simple sequence repeat variation within two island‐endemic Aeonium species of La Palma: one widespread generalist that covers a large variety of different habitat types (Ae. davidbramwellii) and one narrow ecological specialist (Ae. nobile), in order to assess evolutionary potentials on this island. Gene pool differentiation and genetic diversity patterns were associated with major landscape structures in both species, with phylogeographic implications. However, overall levels of genetic differentiation were low. For the generalist species, outlier loci detection and loci–environment correlation approaches indicated moderate signatures of divergent selection pressures linked to temperature and precipitation variables, while the specialist species missed such patterns. Our data point to incipient differentiation among populations, emphasizing that ecological heterogeneity and topographical structuring within the small scales of an island can foster evolutionary processes. Very likely, such processes have contributed to the radiation of Aeonium on the Canary Islands. There is also support for different evolutionary mechanisms between generalist and specialist species.

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Population genetic suggestions to offset the extinction ratchet in the endangered Canarian endemic Atractylis preauxiana (Asteraceae)

Cited by 11 publications

References 28 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

Population genetics at three spatial scales of a rare sponge living in fragmented habitats

Spatial and ecological population genetic structures within two island‐endemic Aeonium species of different niche width

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