Does Macaronesia exist? Conflicting signal in the bryophyte and pteridophyte floras

Vanderpoorten, Alain; Rumsey, Fred; Carine, Mark A.

doi:10.3732/ajb.94.4.625

Cited by 74 publications

(73 citation statements)

References 59 publications

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“…Many bryophyte species exhibit a striking hyper-Atlantic distribution pattern that is often disjunct between Macaronesia and the western fringe of Europe (15). Such distributions may reflect a similar history with Macaronesia serving as a refugium and a source area for the postglacial recolonization of Europe.…”

Section: Resultsmentioning

confidence: 99%

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Oceanic islands are not sinks of biodiversity in spore-producing plants

Hutsemékers

Szövényi

Shaw

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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Islands have traditionally been considered as migratory and evolutionary dead ends for two main reasons: island colonizers are typically assumed to lose their dispersal power, and continental back colonization has been regarded as unlikely because of niche preemption. The hypothesis that islands might actually represent dynamic refugia and migratory stepping stones for species that are effective dispersers, and in particular, for spore-producing plants, is formally tested here, using the archipelagos of the Azores, Canary Islands, and Madeira, as a model. Population genetic analyses based on nuclear microsatellite variation indicate that dispersal ability of the moss Platyhypnidium riparioides does not decrease in the island setting. The analyses further show that, unlike island populations, mainland (southwestern Europe and North Africa) populations underwent a severe bottleneck during the last glacial maximum (LGM). Our results thus refute the traditional view of islands as the end of the colonization road and point to a different perception of North Atlantic archipelagos as major sources of biodiversity for the postglacial recolonization of Europe by spore-producing plants.biogeography | speciation | genetic diversity | island syndromes | isolation-with-migration I sland biogeography has historically been and remains a research area of prime importance for the advance of biology (1). It was in an island setting that Darwin (2) and Wallace (3) presented their theories of evolution by natural selection. It was also in this context that McArthur and Wilson (4) described the "equilibrium model," according to which biodiversity patterns can be explained by isolation from source populations (immigration) and area size (extinction). Oceanic islands hence appear as natural laboratories of evolutionary and biogeographic processes and Wallace (5) suggested that understanding evolutionary processes within an island context is a key to understanding the same mechanisms in the more complex continental settings.Theoretical work on population structure has used island models as paradigms for understanding how interactions between gene flow, effective population size, and genetic drift influence patterns of genetic variation. Although surprisingly few studies have explicitly tested models of population structure and diversity in island and mainland plant populations (6), theory predicts that island populations should be less variable and more genetically differentiated relative to source populations (7). Differentiation of island populations is further enhanced by one of the most striking syndromes displayed by island taxa, that is, their typical loss of dispersal power as a result of either absence of predation and/or competition in the island setting or counter selection against high dispersal ability associated with the risk of massive individual loss to surrounding sea water (8). This process can be fairly rapid. In the annual daisy Lactuca muralis, for example, a substantial and significant loss of dispersal power owing...

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Section: Resultsmentioning

confidence: 99%

“…1), which form a distinct biogeographic unit referred to as Macaronesia (sensu ref. 15), we confront theoretical expectations on patterns of genetic diversity in the moss Platyhypnidium riparioides. We aim to determine whether dispersal ability of this moss erode any signature of founding events on extant patterns of genetic variation.…”

mentioning

confidence: 99%

Oceanic islands are not sinks of biodiversity in spore-producing plants

Hutsemékers

Szövényi

Shaw

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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“…We assumed that the nearest continent was the main source area for islands. This assumption is supported in Macaronesia, a biogeographical region comprised of the Azores, Canary Islands and Madeira, where the bryophyte flora exhibits closer affinities with the European flora than with any of the other floras world-wide (Vanderpoorten, Carine & Rumsey 2007). Because island species are assumed to originate from a continental ancestor, and because island taxa are expected to evolve syndromes in response to the specificities of the island environment (see Whittaker & Fern andez-Palacios 2007; for review), we further assumed that character states observed in islands are derived.…”

Section: S E L E C T I O N a N D S C O R I N G O F L I F E -H I S T Omentioning

confidence: 92%

Baker's law and the island syndromes in bryophytes

et al. 2013

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Summary1. The evolution of island syndromes has long served as a model to understand the mechanisms accounting for phenotypic differentiation. Combining literature data with actual observations, we determine whether typical syndromes such as the loss of dispersal power and the bias towards selfcompatibility (Baker's law) apply to vagile organisms, using bryophytes as a model. 2. The life-history traits (LHTs) observed in oceanic island floras were statistically different from those observed on continents, evidencing the evolution of island syndromes. In contrast, LHTs of continental and continental island floras were similar, pointing to differences in migration intensity between continents, continental islands and oceanic islands. 3. The proportion of bisexual species was significantly higher on oceanic islands than on continents. A significant proportion of species that are unisexual or bisexual on continents shifted towards exclusive bisexuality on oceanic islands, suggesting that Baker's law applies to bryophytes. The underlying mechanisms, however, probably differ from in situ selection for selfing. 4. The proportion of species producing specialized asexual diaspores, which are assumed to play a role in short-distance dispersal (SDD), was higher on oceanic islands than on continents. The proportion of species producing spores, which are involved in long-distance dispersal (LDD), exhibited the reverse trend, suggesting a shift in the prevalent reproductive strategy to favour SDD on oceanic islands. Approximately 50% of the species, however, maintained the ability to produce sporophytes on oceanic islands, and the relative frequency of fertile shoots within collections of four model species was even higher on islands than on continents. 5. Synthesis. Bryophytes exhibit typical island syndromes, indicating that migration rates between oceanic islands and continents are not sufficient to prevent the effects of genetic drift and contradicting the view that the sea does not impede migration in the group. Significant shifts in life-history traits (LHTs) towards increased production of specialized asexual diaspores and decreased sporophyte production on oceanic islands indeed point to a global loss of long-distance dispersal (LDD) ability. The maintenance of traits characteristic for LDD in a large number of species has, however, substantial consequences for our understanding of island plant evolution, and in particular, for our vision of islands as evolutionary dead ends.

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“…We excluded the Azores, Canary Islands and Madeira (Macaronesia) because their high degree of endemism points to their development being independent from Europe (Wunderlich 1991), with more affinities to Africa (e.g., Lloris et al 1991;Vanderpoorten et al 2007). This definition corresponds to that used by the ''araneae-Spiders of Europe'' website ).…”

Section: Biogeographical Definition Of Europementioning

confidence: 99%

Introduction, establishment rate, pathways and impact of spiders alien to Europe

Nentwig

2015

Biol Invasions

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A comprehensive analysis of spiders reported as alien for Europe over the last 200 years has yielded information for 184 spider species, which had been introduced at least once. The most common spider families are Theridiidae (27 species), Pholcidae (15), Salticidae (14), Sparassidae (14), Ctenidae (14), and Theraphosidae (13) but overall establishment rate was only 28 %. No ctenids or theraphosids established, and only one sparassid species, but many theridiids and pholcids. Most introduced species originated from South (34 %), Central (10 %) or North (12 %), America, Asia (19 %) and Africa (15 %). Only few of the South and Central American species could establish, while species from North America (36 %) and Asia (63 %) had much higher establishment rates. Over the last 200 years, introduction and establishment rates have been strongly increasing. Three pathways are responsible for the majority of introductions: fruit shipments (67 % of all cases), potted plants (16 %) and containers or packaging material (12 %). In contrast to fruit shipments, spiders introduced on plants or with containers have high establishment rates (65 and 47 %). Environmental impact of alien spiders can be expected on both insects (through predation) and spiders (through predation and competition), potentially leading to change of species composition and guild structure. Socio-economic impact includes

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Does Macaronesia exist? Conflicting signal in the bryophyte and pteridophyte floras

Cited by 74 publications

References 59 publications

Oceanic islands are not sinks of biodiversity in spore-producing plants

Oceanic islands are not sinks of biodiversity in spore-producing plants

Baker's law and the island syndromes in bryophytes

Introduction, establishment rate, pathways and impact of spiders alien to Europe

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