The Azores diversity enigma: why are there so few Azorean endemic flowering plants and why are they so widespread?

Aim Endemism in the flora of the Azores is high (33%) but in other respects, notably the paucity of evolutionary radiations and the widespread distribution of most endemics, the flora differs markedly from the floras of the other Macaronesian archipelagos. We evaluate hypotheses to explain the distinctive patterns observed in the Azorean endemic flora, focusing particularly on comparisons with the Canary Islands. Location Azores archipelago. Methods Data on the distribution and ecology of Azorean endemic flowering plants are reviewed to ascertain the incidence of inter‐island allopatric speciation and adaptive, ecological speciation. These are contrasted with patterns for the Canary Islands. Patterns of endemism in the Azores and Canaries are further investigated in a phylogenetic context in relation to island age. beast was used to analyse a published molecular dataset for Pericallis (Asteraceae) and to investigate the relative ages of Azorean and Canarian lineages. Results There are few examples of inter‐island allopatric speciation in the Azorean flora, despite the considerable distances between islands and sub‐archipelagos. In contrast, inter‐island allopatric speciation has been an important process in the evolution of the Canary Islands flora. Phylogenetic data suggest that Azorean endemic lineages are not necessarily recent in origin. Furthermore, in Pericallis the divergence of the Azorean endemic lineage from its closest relative pre‐dates the radiation of a Canarian herbaceous clade by inter‐island allopatric speciation. Main conclusions The data presented do not support suggestions that hypotheses pertaining to island age, age of endemic lineages and ecological diversity considered individually explain the lack of radiations and the widespread distribution of Azorean endemics. We suggest that palaeoclimatic variation, a factor rarely considered in macroecological studies of island diversity patterns, may be an important factor. Palaeoclimatic data suggest frequent and abrupt transitions between humid and arid conditions in the Canaries during the late Quaternary, and such an unstable climate may have driven the recent diversification of the flora by inter‐island allopatric speciation, a process largely absent from the climatically more stable Azores. Further phylogenetic/phylogeographic analyses are necessary to determine the relative importance of palaeoclimate and other factors in generating the patterns observed.     

Phylogeography and molecular phylogeny of Macaronesian island Tarphius (Coleoptera: Zopheridae): why are there so few species in the Azores?

Aim We used a phylogenetic framework to examine island colonization and predictions pertaining to differentiation within Macaronesian Tarphius (Insecta, Coleoptera, Zopheridae), and explain the paucity of endemics in the Azores compared with other Macaronesian archipelagos. Specifically, we test whether low diversity in the Azores could be due to recent colonization (phylogenetic lineage youth), cryptic speciation (distinct phylogenetic entities within species) or the young geological age of the archipelago. Location Macaronesian archipelagos (Azores, Madeira and the Canary Islands), northern Portugal and Morocco. Methods Phylogenetic analyses of mitochondrial and nuclear genes of Tarphius beetles of the Azores, other Macaronesian islands and neighbouring continental areas were used to investigate the origin of island biodiversity and to compare patterns of colonization and differentiation. A comparative nucleotide substitution rate test was used to select the appropriate substitution rate to infer clade divergence times. Results Madeiran and Canarian Tarphius species were found to be more closely related to each other, while Azorean taxa grouped separately. Azorean taxa showed concordance between species and phylogenetic clades, except for species that occur on multiple islands, which segregated by island of origin. Divergence time estimates revealed that Azorean Tarphius are an old group and that the most recent intra‐island speciation event on Santa Maria, the oldest island, occurred between 3.7 and 6.1 Ma. Main conclusions Our phylogenetic approach provides new evidence to understand the impoverishment of Azorean endemics: (1) Tarphius have had a long evolutionary history within the Azores, which does not support the hypothesis of fewer radiation events due to recent colonization; (2) the current taxonomy of Azorean Tarphius does not reflect common ancestry and cryptic speciation is responsible for the underestimation of endemics; (3) intra‐island differentiation in the Azores was found only in the oldest island, supporting the idea that young geological age of the archipelago limits the number of endemics; and (4) the lack of evidence for recent intra‐island diversification in Santa Maria could also explain the paucity of Azorean endemics. Phylogenetic reconstructions of other species‐rich taxa that occur on multiple Macaronesian archipelagos will reveal whether our conclusions are taxon specific, or of a more general nature.     

Additive partitioning as a tool for investigating the flora diversity in oceanic archipelagos

This paper introduces the integration of additive partitioning with species—area relationships to island biogeography in order to address the question “How are the pteridophyte and spermatophyte native and endemic flora of different oceanic archipelagos partitioned across islands?”.Species richness data of all endemic species and all native species of pteridophytes and spermatophytes were obtained for the Azores, Canaries and Cape Verde in the Atlantic Ocean and Galápagos, Hawaii and Marquesas in the Pacific Ocean. Additive partitioning of species diversity was used to quantify how much of the total diversity of an oceanic archipelago flora (γ-diversity) is due to (i) the mean species richness of the flora of each island (α-diversity), (ii) the variability in species richness of the floras across islands (β_Nestedness) and (iii) the complementarity in species composition of the floras of different islands (β_Replacement). The analysis was separately performed for the native and endemic pteridophyte and spermatophyte floras.The diversity partitioning of the six archipelagos showed large differences in how the flora of each archipelago is partitioned among the α, β_Nestedness and β_Replacement components, for pteridophytes and spermatophytes and for all endemic species and all native species. The α-diversity was more important for all native species than for endemic species and more important for pteridophytes than for spermatophytes, with the Azores showing outstanding high values of α-diversity. The β_Nestedness was higher for pteridophytes than for spermatophytes and higher for endemic species than for all native species in both pteridophytes and spermatophytes. The values of β_Replacement suggested that: (i) the spermatophyte native flora is more differentiated across islands than the pteridophyte native flora and (ii) the pteridophyte endemic flora and, especially, the spermatophyte endemic flora are more differentiated across islands than the corresponding native flora. An outstanding value of β_Replacement for endemic and all native spermatophytes was found in Hawaii, confirming the biogeographical island differentiation in this archipelago.     

Drivers of diversity in Macaronesian spiders and the role of species extinctions

Aim To identify the biogeographical factors underlying spider species richness in the Macaronesian region and assess the importance of species extinctions in shaping the current diversity. Location The European archipelagos of Macaronesia with an emphasis on the Azores and Canary Islands. Methods Seven variables were tested as predictors of single‐island endemics (SIE), archipelago endemics and indigenous spider species richness in the Azores, Canary Islands and Macaronesia as a whole: island area; geological age; maximum elevation; distance from mainland; distance from the closest island; distance from an older island; and natural forest area remaining per island – a measure of deforestation (the latter only in the Azores). Different mathematical formulations of the general dynamic model of oceanic island biogeography (GDM) were also tested. Results Island area and the proportion of remaining natural forest were the best predictors of species richness in the Azores. In the Canary Islands, area alone did not explain the richness of spiders. However, a hump‐shaped relationship between richness and time was apparent in these islands. The island richness in Macaronesia was correlated with island area, geological age, maximum elevation and distance to mainland. Main conclusions In Macaronesia as a whole, area, island age, the large distance that separates the Azores from the mainland, and the recent disappearance of native habitats with subsequent unrecorded extinctions seem to be the most probable explanations for the current observed richness. In the Canary Islands, the GDM model is strongly supported by many genera that radiated early, reached a peak at intermediate island ages, and have gone extinct on older, eroded islands. In the Azores, the unrecorded extinctions of many species in the oldest, most disturbed islands seem to be one of the main drivers of the current richness patterns. Spiders, the most important terrestrial predators on these islands, may be acting as early indicators for the future disappearance of other insular taxa.     

Time, area and isolation: factors driving the diversification of Azorean arthropods

Aim R. J. Whittaker et al. recently proposed a ‘general dynamic model of oceanic island biogeography’ (GDM), providing a general explanation of island biodiversity patterns by relating fundamental biogeographical processes – speciation, immigration, extinction – to area (A) and time (T; maximum island geological age). We adapt their model, which predicts a positive relationship with area combined with a humped relationship to time (designated the ATT² model), to study the factors promoting diversification on the Azores for several arthropod groups. Location The Azorean archipelago (North Atlantic; 37–40° N, 25–31° W). Methods We use the number of single‐island endemics (SIEs) as a measure of diversification, to evaluate four different predictions for the variation in SIEs between different islands, derived from the GDM theory and our knowledge of the fauna and history of the Azores. We calculated the number of SIEs for seven out of the nine Azorean islands and six groups of species (all arthropods, beetles, cavernicolous and non‐cavernicolous species, and taxa with high and low dispersal abilities). Several variables accounting for island characteristics (area, geological age, habitat diversity and isolation) and generalized linear models were used to evaluate the reliability of each prediction. Results A linear and positive relationship between SIEs and an AT (area + time) model was the most parsimonious explanation for overall arthropod diversification. However, cavernicolous species showed the opposite pattern (more SIEs inhabiting the youngest islands). Also, isolation was an important predictor of diversification for all groups except for the species with high dispersal ability; while the former were negatively related to the distance from the main source of colonizing lineages (Santa Maria island in most cases), the latter were related to area. Dispersal ability was also a key factor affecting the diversification of most groups of species. Main conclusions In general, the diversification of Azorean arthropods is affected by age, area and isolation. However, different groups are affected by these factors in different ways, showing radically different patterns. Although the ATT² model fails to predict the diversification pattern of several groups, it provides a framework for integrating these deviations into a general theory. Further improvements of the GDM theory need to take into account the particular traits of each group and the role of isolation in shaping island diversity.     

Patterns of cladogenesis in the venomous marine gastropod genus Conus from the Cape Verde islands

Isolated oceanic archipelagos are excellent model systems to study speciation, biogeography, and evolutionary factors underlying the generation of biological diversity. Despite the wealth of studies documenting insular speciation, few of them focused on marine organisms. Here, we reconstruct phylogenetic relationships among species of the marine venomous gastropod genus Conus from the Cape Verde archipelago. This small island chain located in the Central Atlantic hosts 10% of the worldwide species diversity of Conus. Analyses were based on mtDNA sequences, and a novel nuclear marker, a megalin-like protein, member of the low-density lipoprotein receptor gene family. The inferred phylogeny recovered two well-defined clades within Conus. One includes Cape Verde endemic species with larger shells, known as the "venulatus" complex together with C. pulcher from the Canary Islands. The other is composed of Cape Verde endemic and West Africa and Canary Island "small" shelled species. In both clades, nonendemic Conus were resolved as sister groups of the Cape Verde endemics, respectively. Our results indicate that the ancestors of "small" and "large" shelled lineages independently colonized Cape Verde. The resulting biogeographical pattern shows the grouping of most Cape Verde endemics in monophyletic island assemblages. Statistical tests supported a recent radiation event within the "small shell" clade. Using a molecular clock, we estimated that the colonization of the islands by the "small" shelled species occurred relatively close to the origin of the islands whereas the arrival of "large" shelled Conus is more recent. Our results suggest that the main factor responsible for species diversity in the archipelago may be allopatric speciation promoted by the reduced dispersal capacity of nonplanktonic lecithotrophic larvae.     

Mitochondrial DNA patterns in the Macaronesia islands: Variation within and among archipelagos

Macaronesia covers four Atlantic archipelagos: the Azores, Madeira, the Canary Islands, and the Cape Verde islands. When discovered by Europeans in the 15th century, only the Canaries were inhabited. Historical reports highlight the impact of Iberians on settlement in Macaronesia. Although important differences in their settlement are documented, its influence on their genetic structures and relationships has yet to be ascertained. In this study, the hypervariable region I (HVRI) sequence and coding region polymorphisms of mitochondrial DNA (mtDNA) in 623 individuals from the Azores (120) and Canary Islands (503) were analyzed. Combined with published data, these give a total of 1,542 haplotypes from Macaronesia and 1,067 from the Iberian Peninsula. The results obtained indicate that Cape Verde is the most distinctive archipelago, with an mtDNA pool composed almost exclusively of African lineages. However, the other archipelagos present an mtDNA profile dominated by the presence of West‐Eurasian mtDNA haplogroups with African lineages present in varying proportions. Moreover, no signs of integration of typical Canarian U6 lineages in the other archipelagos were detected. The four Macaronesia archipelagos currently have differentiated genetic profiles, and the Azores present the highest intra‐archipelago differentiation and the lowest values of diversity. The analyses performed show that the present‐day genetic profile of the Macaronesian archipelagos was mainly determined by the initial process of settlement and further microdifferentiation probably as a consequence of the small population size of some islands. Moreover, contacts between archipelagos seem to have had a low impact on the mtDNA genetic pool of each archipelago. Am J Phys Anthropol, 2010. © 2009 Wiley‐Liss, Inc.     

Resolving the Azorean knot: a response to Carine & Schaefer (2010)

Carine & Schaefer (Journal of Biogeography, 2010, 37 , 77–89) suggest that the lack of past climate oscillations in the Azores may have contributed to the low plant endemism in this archipelago compared to that of the Canary Islands, a pattern they term the Azorean diversity enigma. Here we challenge their hypothesis, and discuss how the particular characteristics of the Azores may have driven current diversification patterns in this archipelago. We argue that the restricted number of Azorean endemic species and their wide distribution is explicable by the geological, geographical and ecological attributes of the archipelago. That is, the Azores are too young, too small, and too environmentally homogeneous to have hosted many in situ diversification events, so they do not host as many endemic species as other Macaronesian archipelagos, such as Madeira and especially the Canary Islands.     

Phylogeography of a Marine Insular Endemic in the Atlantic Macaronesia: The Azorean Barnacle,Megabalanus azoricus (Pilsbry, 1916)

The Azorean barnacle, Megabalanus azoricus (Pilsbry, 1916), is a Macaronesian endemic whose obscure taxonomy and the unknown relationships among forms inhabiting isolated Northern Atlantic oceanic islands is investigated by means of molecular analysis herein. Mitochondrial data from the 16S rRNA and COX1 genes support its current species status, tropical ancestry, and the taxonomic homogeneity throughout its distribution range. In contrast, at the intraspecific level and based on control region sequences, we detected an overall low level of genetic diversity and three divergent lineages. The haplogroups α and γ were sampled in the Azores, Madeira, Canary, and Cabo Verde archipelagos; whereas haplogroup β was absent from Cabo Verde. Consequently, population analysis suggested a differentiation of the Cabo Verde population with respect to the genetically homogenous northern archipelagos generated by current oceanographic barriers. Furthermore, haplogroup α, β, and γ demographic expansions occurred during the interglacial periods MIS5 (130 Kya - thousands years ago -), MIS3 (60 Kya), and MIS7 (240 Kya), respectively. The evolutionary origin of these lineages is related to its survival in the stable southern refugia and its demographic expansion dynamics are associated with the glacial-interglacial cycles. This phylogeographic pattern suggests the occurrence of genetic discontinuity informative to the delimitation of an informally defined biogeographic entity, Macaronesia, and its generation by processes that delineate genetic diversity of marine taxa in this area.     

Putting biogeography’s cart back behind taxonomy’s horse: a response to Triantis et al.

In a recent paper, two of us discussed diversity patterns and diversification processes in the Azores flora. Triantis et al. (2012, Journal of Biogeography, 39, 1179–1184) challenged our hypothesis that palaeoclimatic differences had an effect on diversification rates and suggested that area, island age and isolation explain diversity patterns. They did not, however, fully address the results from our subsequent paper, in which we showed that diversity patterns evident from phylogeographic studies differ markedly from those suggested by checklists. Checklists are working hypotheses and we suggest that the discrepancies evident between molecular data and checklists may be indicative of deficiencies in our taxonomic understanding of the Azores flora. Patterns of molecular and morphological diversity need to be better understood, and the discrepancies between checklists and molecular data accounted for, before we can establish the relative importance of factors such as palaeoclimate, area, island age or isolation in generating endemic diversity patterns in the Azores flora.     

Effects of climate change on the distribution of plant species and plant functional strategies on the Canary Islands

Aim

Oceanic islands possess unique floras with high proportions of endemic species. Island floras are expected to be severely affected by changing climatic conditions as species on islands have limited distribution ranges and small population sizes and face the constraints of insularity to track their climatic niches. We aimed to assess how ongoing climate change affects the range sizes of oceanic island plants, identifying species of particular conservation concern.

Location

Canary Islands, Spain.

Methods

We combined species occurrence data from single-island endemic, archipelago endemic and nonendemic native plant species of the Canary Islands with data on current and future climatic conditions. Bayesian Additive Regression Trees were used to assess the effect of climate change on species distributions; 71% (n = 502 species) of the native Canary Island species had models deemed good enough. To further assess how climate change affects plant functional strategies, we collected data on woodiness and succulence.

Results

Single-island endemic species were projected to lose a greater proportion of their climatically suitable area (x ̃ = −0.36) than archipelago endemics (x ̃ = −0.28) or nonendemic native species (x ̃ = −0.26), especially on Lanzarote and Fuerteventura, which are expected to experience less annual precipitation in the future. Moreover, herbaceous single-island endemics were projected to gain less and lose more climatically suitable area than insular woody single-island endemics. By contrast, we found that succulent single-island endemics and nonendemic natives gain more and lose less climatically suitable area.

Main Conclusions

While all native species are of conservation importance, we emphasise single-island endemic species not characterised by functional strategies associated with water use efficiency. Our results are particularly critical for other oceanic island floras that are not constituted by such a vast diversity of insular woody species as the Canary Islands.     

A general dynamic theory of oceanic island biogeography

Aim MacArthur and Wilson’s dynamic equilibrium model of island biogeography provides a powerful framework for understanding the ecological processes acting on insular populations. However, their model is known to be less successful when applied to systems and processes operating on evolutionary and geological timescales. Here, we present a general dynamic model (GDM) of oceanic island biogeography that aims to provide a general explanation of biodiversity patterns through describing the relationships between fundamental biogeographical processes – speciation, immigration, extinction – through time and in relation to island ontogeny. Location Analyses are presented for the Azores, Canaries, Galápagos, Marquesas and Hawaii. Methods We develop a theoretical argument from first principles using a series of graphical models to convey key properties and mechanisms involved in the GDM. Based on the premises (1) that emergent properties of island biotas are a function of rates of immigration, speciation and extinction, (2) that evolutionary dynamics predominate in large, remote islands, and (3) that oceanic islands are relatively short‐lived landmasses showing a characteristic humped trend in carrying capacity (via island area, topographic variation, etc.) over their life span, we derive a series of predictions concerning biotic properties of oceanic islands. We test a subset of these predictions using regression analyses based largely on data sets for native species and single‐island endemics (SIEs) for particular taxa from each archipelago, and using maximum island age estimates from the literature. The empirical analyses test the power of a simple model of diversity derived from the GDM: the log(Area) + Time + Time² model (ATT²), relative to other simpler time and area models, using several diversity metrics. Results The ATT² model provides a more satisfactory explanation than the alternative models evaluated (for example the standard diversity–area models) in that it fits a higher proportion of the data sets tested, although it is not always the most parsimonious solution. Main conclusions The theoretical model developed herein is based on the key dynamic biological processes (migration, speciation, extinction) combined with a simple but general representation of the life cycle of oceanic islands, providing a framework for explaining patterns of biodiversity, endemism and diversification on a range of oceanic archipelagos. The properties and predictions derived from the model are shown to be broadly supported (1) by the empirical analyses presented, and (2) with reference to previous phylogenetic, ecological and geological studies.     

In and out of Madagascar: Dispersal to Peripheral Islands, Insular Speciation and Diversification of Indian Ocean Daisy Trees (Psiadia, Asteraceae)

Madagascar is surrounded by archipelagos varying widely in origin, age and structure. Although small and geologically young, these archipelagos have accumulated disproportionate numbers of unique lineages in comparison to Madagascar, highlighting the role of waif-dispersal and rapid in situ diversification processes in generating endemic biodiversity. We reconstruct the evolutionary and biogeographical history of the genus Psiadia (Asteraceae), a plant genus with near equal numbers of species in Madagascar and surrounding islands. Analyzing patterns and processes of diversification, we explain species accumulation on peripheral islands and aim to offer new insights on the origin and potential causes for diversification in the Madagascar and Indian Ocean Islands biodiversity hotspot. Our results provide support for an African origin of the group, with strong support for non-monophyly. Colonization of the Mascarenes took place by two evolutionary distinct lineages from Madagascar, via two independent dispersal events, each unique for their spatial and temporal properties. Significant shifts in diversification rate followed regional expansion, resulting in co-occurring and phenotypically convergent species on high-elevation volcanic slopes. Like other endemic island lineages, Psiadia have been highly successful in dispersing to and radiating on isolated oceanic islands, typified by high habitat diversity and dynamic ecosystems fuelled by continued geological activity. Results stress the important biogeographical role for Rodrigues in serving as an outlying stepping stone from which regional colonization took place. We discuss how isolated volcanic islands contribute to regional diversity by generating substantial numbers of endemic species on short temporal scales. Factors pertaining to the mode and tempo of archipelago formation and its geographical isolation strongly govern evolutionary pathways available for species diversification, and the potential for successful diversification of dispersed lineages, therefore, appears highly dependent on the timing of arrival, as habitat and resource properties change dramatically over the course of oceanic island evolution.     

Non‐random patterns of invasion and extinction reduce phylogenetic diversity in island bird assemblages

Anthropogenically driven changes in bird communities on oceanic islands exemplify the biotic upheaval experienced by island floras and faunas. While the influence of invasions and extinctions on species richness and beta‐diversity of island bird assemblages has been explored, little is known about the impact of these invasions and extinctions on phylogenetic diversity. Here we quantify phylogenetic diversity of island bird assemblages resulting from extinctions alone, invasions alone, and the combination of extinctions and invasions in the historic time period (1500 CE to the current), and compare it to the expected phylogenetic diversity that would result if these processes involved randomly selected island bird species. We assessed phylogenetic diversity and structure at the scale of the island (n = 152), the archipelago containing the islands (n = 22), and the four oceans containing the archipelagos using three measures. We found that extinction, invasion, and the combination of invasion and extinction generally resulted in lower phylogenetic diversity than expected, regardless of the spatial scale examined. We conclude that extinction and invasion of birds on islands are non‐random with respect to phylogeny and that these processes generally leave bird assemblages with lower phylogenetic diversity than we would expect under random invasion or extinction.     

Endemic Seed Plants in the Bahamian Archipelago

The Bahamian archipelago consists of approximately 2,400 islands occurring in the Atlantic Ocean off the coasts of Florida, Cuba, and Hispaniola. In 1982 Donovan Correll and Helen Correll published the most current synopsis of the floristic diversity of this island chain. Their publication cited a total of 1,371 vascular plant species of which 114 seed plants were listed as endemic to the archipelago (~8 % of the native flora). In the last 30 years, additional herbarium collections and taxonomic studies have shown that a number of species previously indicated to be endemic to these islands also occur in other regions or have been taxonomically merged into other species. The current number of species considered endemic to the Bahamian archipelago is 89 (~6 % of the total flora). There are 50 endemic species that have a known distribution on one (31 species) or two island groupings (19 species). Biogeographical analyses of endemic plant distributions shows three distinct clusters of species: southern, central, and the northern islands, with a fourth cluster that includes islands with a small area and one medium size island that seems that has been underexplored (i.e., Little Inagua). We anticipate that understanding the conservation status of endemic species and their distributions will help to develop legislation to preserve this Bahamian natural heritage.     

Mitochondrial DNA variation and population structure of the island endemic Azorean bat (Nyctalus azoreum)

The Azorean bat Nyctalus azoreum is the only endemic mammal native to the remote archipelago of the Azores. It evolved from a continental ancestor related to the Leisler's bat Nyctalus leisleri and is considered threatened because of its restricted and highly fragmented distribution. We studied the genetic variability in 159 individuals from 14 colonies sampled throughout the archipelago. Sequences of the D-loop region revealed moderate but highly structured genetic variability. Half of the 15 distinct haplotypes were restricted to a single island, but the most common was found throughout the archipelago, suggesting a single colonization event followed by limited interisland female gene flow. All N. azoreum haplotypes were closely related and formed a star-like structure typical of expanded populations. The inferred age of demographic expansions was consistent with the arrival of founder animals during the Holocene, well before the first humans inhabited the Azores. Comparisons with a population of N. leisleri from continental Portugal confirmed not only that all N. azoreum lineages were unique to the archipelago, but also that the current levels of genetic diversity were surprisingly high for an insular species. Our data imply that the Azorean bat has a high conservation value. We argue that geographical patterns of genetic structuring indicate the existence of two management units.     

Spider biodiversity patterns and their conservation in the Azorean archipelago,with descriptions of new species

Abstract

In this contribution, we report on patterns of spider species diversity of the Azores, based on recently standardised sampling protocols in different habitats of this geologically young and isolated volcanic archipelago. A total of 122 species is investigated, including eight new species, eight new records for the Azorean islands and 61 previously known species, with 131 new records for individual islands. Biodiversity patterns are investigated, namely patterns of range size distribution for endemics and non‐endemics, habitat distribution patterns, island similarity in species composition and the estimation of species richness for the Azores. Newly described species are: Oonopidae ‐ Orchestina furcillata Wunderlich; Linyphiidae: Linyphiinae ‐ Porrhomma borgesi Wunderlich; Turinyphia cavernicola Wunderlich; Linyphiidae: Micronetinae ‐Agyneta depigmentata Wunderlich; Linyphiidae: Erigoninae ‐ Acorigone gen. nov. with its type species Acorigone zebraneus Wunderlich; Clubionidae ‐ Cheiracanthium floresense Wunderlich; Cheiracanthium jorgeense Wunderlich; Salticidae ‐ Neon acoreensis Wunderlich. Other major taxonomic changes are: Diplocentria acoreensis Wunderlich, 1992 (Linyphiidae) is transferred to Acorigone (comb. nov.), Leucognatha Wunderlich 1995 (Tetragnathidae) is not an endemic genus of the Azores but an African taxon and synonymous with Sancus Tullgren, 1910; Leucognatha acoreensis Wunderlich, 1992 is transferred to Sancus. Minicia picoensis Wunderlich, 1992 is a synonym of M. floresensis Wunderlich, 1992. For each species additional information is presented about its known distribution in the islands, its colonisation status, habitat occurrence and biogeographical origin.     

Genetic diversity and morphological variation of the common chaffinch Fringilla coelebs in the Azores

We present new insights into the genetic diversity and phylogeography of the common chaffinch Fringilla coelebs from the Azores, based on sequences of mitochondrial and nuclear genes from 44 individuals and an outgroup/comparison of 44 birds from Madeira, the Canary Islands and the Continental Western Palearctic. To understand the level of concordance between the genetic data and morphometric variability we analysed eight morphometric characters from 413 adult living birds from all the Azores islands and compared the population genetic distances with quantitative morphometric traits. Our results indicate the occurrence of gene flow among the common chaffinch populations in the archipelago revealing the lack of current genetic structure within it and the existence of two co‐occurring lineages. Results also indicate the existence of morphometric differences among islands that could be due to ecological features instead of island isolation. This study also confirms the genetic distance among the common chaffinch populations within Macaronesia and between these archipelagos and the Continental Western Palearctic.     

Uniform phenotype conceals double colonization by reed-warblers of a remote Pacific archipelago

Aim Remote oceanic islands often provide good illustrations of adaptive radiations, but phylogenetic studies have also demonstrated unexpected multiple colonization events for a given archipelago. In this study we investigate the relationships among endemic populations of the Marquesas reed‐warbler, Acrocephalus mendanae Tristram, 1883, which have colonized nearly all islands of this remote Polynesian archipelago, and which exhibit a very uniform plumage pattern. We study the phylogeny and morphology of all subspecies in the Marquesas, providing an examination of the position of the Marquesas lineages in relation to reed‐warblers distributed across multiple Polynesian archipelagos. Location This study focused on all the main islands of the Marquesas archipelago, along with samples from other Polynesian archipelagos (Society, Tuamotu, Austral, Cook, Kiribati) and Australia. Methods We used mitochondrial DNA markers (cytochrome b and ND2 genes) to develop a phylogeny of the main eastern Polynesian taxa. All subspecies for the Marquesas were investigated, including multiple individuals per island. Phylogenetic analyses using maximum‐likelihood and Bayesian approaches were employed to infer relationships among A. mendanae populations and between the main Polynesian archipelagos. Morphometric analyses based on 110 specimens from museum collections were performed on external characters to investigate the differences between islands, and these results were compared to the phylogeny. Results Our data indicate that the Marquesas reed‐warbler is in fact a polyphyletic taxon including two independent lineages: the northern Marquesas reed‐warbler, closely related to the Tuamotu reed‐warbler, and the southern Marquesas reed‐warbler, sister taxon to that endemic to the Kiribati. Analyses of morphological characters show that the size and shape features of the Marquesas reed‐warblers exhibit high plasticity linked to adaptation to ecological factors, particularly habitat richness (the diversity of vegetation structure that provides suitable resources and habitat for reed‐warblers, simplified here as the number of indigenous plant species). Main conclusions Our results suggest that reed‐warblers have successfully colonized the Marquesas archipelago, one of the most remote groups of islands in the Pacific Ocean, at least twice. Both events occurred more or less simultaneously at ca. 0.6 Ma, and are more recent than the islands' formation. We outline the taxonomic consequences of our phylogeny and discuss the supertramp strategy of reed‐warblers in the Pacific.     

Plant diversity in Oceanic archipelagos: realistic patterns emulated by an agent‐based computer simulation

Although islands as natural laboratories have held the attention of scientists for centuries, they continue to offer new study questions, especially in the context of the current biodiversity crisis. To date, habitat diversity on islands and spatial configuration of archipelagos have received less attention than classical island area and isolation. Moreover, in the field where experiments are impossible, correlative methods have dominated, despite the call for more mechanistic approaches. We developed an agent‐based computer simulation to study the effect of habitat diversity and archipelago configuration on plant species richness and composition in five archipelagos worldwide (Hawaii, Galapagos, Canary Islands, Cape Verde and Azores) and compared simulated diversity patterns to the empirical data. Habitat diversity proved to be an important factor to achieve realistic simulation results in all five archipelagos, whereas spatial structure of archipelagos was important in more elongated archipelagos. In most cases, simulation results correlate stronger with spermatophyte than with pteridophyte data, which we suggest can be attributed to the different dispersal and evolution rates of the two species groups. Correlation strength between simulated and observed diversity also varied among archipelagos, suggesting that geological and biogeographic histories of archipelagos have affected the species richness and composition on the islands. Our study demonstrates that a relatively simple computer simulation involving just a few essential processes can largely emulate patterns of archipelagic species richness and composition and serve as a powerful additional method to complement empirical approaches.