Multiple colonizations, in situ speciation, and volcanism-associated stepping-stone dispersals shaped the phylogeography of the Macaronesian red fescues (Festuca L., Gramineae)

Whereas examples of insular speciation within the endemic-rich Macaronesian hotspot flora have been documented, the phylogeography of recently evolved plants in the region has received little attention. The Macaronesian red fescues constitute a narrow and recent radiation of four closely related diploid species distributed in the Canary Islands (F. agustinii), Madeira (F. jubata), and the Azores (F. francoi and F. petraea), with a single extant relative distributed in mainland southwest Europe (F. rivularis). Bayesian structure and priority consensus tree approaches and population spatial correlations between genetic, geographical, and dispersal distances were used to elucidate the phylogeographical patterns of these grasses. Independent versus related origins and dispersal versus isolation by distance (IBD) hypotheses were tested to explain the genetic differentiation of species and populations, respectively. Genetic structure was found to be geographically distributed among the archipelagos and the islands endemics. The high number of shared AFLP fragments in all four species suggests a recent single origin from a continental Pliocene ancestor. However, the strong allelic structure detected among the Canarian, Madeiran, and Azorean endemics and the significant standardized residual values obtained from structured Bayesian analysis for pairwise related origin hypotheses strongly supported the existence of three independent continental-oceanic colonization events. The Canarian F. agustinii, the Madeiran F. jubata, and the two sister F. francoi and F. petraea Azorean species likely evolved from different continental founders in their respective archipelagos. Despite the short span of time elapsed since colonization, the two sympatric Azorean species probably diverged in situ, following ecological adaptation, from a common ancestor that arrived from the near mainland. Simple dispersal hypotheses explained most of the genetic variation at the species level better than IBD models. The optimal dispersal model for F. agustinii was a bidirectional centripetal stepping-stone colonization pattern, an eastern-to-western volcanism-associated dispersion was favored for F. francoi, whereas for the recently derived F. petraea a counterintuitive direction of colonization (west-to-east) was suggested. The population-based phylogeographical trends deduced from our study could be used as predictive models for other Macaronesian plant endemics with similar distribution areas and dispersal abilities.     

Genetic structure of house mouse (Mus musculus Linnaeus 1758) populations in the Atlantic archipelago of the Azores: colonization and dispersal

We analyzed the genetic structure and relationships of house mouse (Mus musculus) populations in the remote Atlantic archipelago of the Azores using nuclear sequences and microsatellites. We typed Btk and Zfy2 to confirm that the subspecies Mus musculus domesticus was the predominant genome in the archipelago. Nineteen microsatellite loci (one per autosome) were typed in a total of 380 individuals from all nine Azorean islands, the neighbouring Madeiran archipelago (Madeira and Porto Santo islands), and mainland Portugal. Levels of heterozygosity were high on the islands, arguing against population bottlenecking. The Azorean house mouse populations were differentiated from the Portuguese and Madeiran populations and no evidence of recent migration between the three was obtained. Within the Azores, the Eastern, Western, and Central island groups tended to act as separate genetic units for house mice, with some exceptions. In particular, there was evidence of recent migration events among islands of the Central island group, whose populations were relatively undifferentiated. Santa Maria had genetically distinctive mice, which may relate to its colonization history. © 2013 The Linnean Society of London     

The genus Huperzia (Lycopodiaceae) in the Azores and Madeira

The taxonomy and nomenclature of the genus Huperzia Bernh. in the Azores and Madeira have been reviewed. Plants collected in the Azores and Madeira were characterized morphologically. The independence between two endemic species common to Madeira and the Azores Islands –Huperzia suberecta (Lowe) Tardieu and Huperzia dentata (Herter) Holub – is clearly shown. A clear‐cut morphological separation between these taxa and Huperzia selago (L.) Bernh. ex Schrank & Mart. of continental Europe is established. © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 158 , 522–533.     

Speciation on the Azores islands: congruent patterns in shell morphology, genital anatomy, and molecular markers in endemic land snails (Gastropoda, Leptaxinae)

Morphological data, in combination with molecular data, may provide invaluable insights into speciation processes on archipelagos. Land snails offer ample opportunities to evalutate adaptive and non-adaptive speciation scenarios. However, studies investigating processes of differentiation and speciation on the Azores are scarce. The present study comprises a morphometrical analysis of shell and genital characters in a group of Azorean land snails (Pulmonata, Leptaxinae). Geographical isolation appears to be an important mechanism underlying morphological and molecular differentiation in the Azorean Leptaxini, instead of adaptive radiation through ecological differentiation. Nevertheless, we could not exclude the occurrence of ecological speciation on the oldest island (Santa Maria) where two species that markedly differ in shell-shape co-occur.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 97 , 166–176.     

A taxonomic revision of Crambe section Dendrocrambe (Brassicaceae)

As part of a recent revision of the genus Crambe , based on the morphological study of herbarium and cultivated material, the systematics of section Dendrocrambe DC. are reviewed here. Section Dendrocrambe (including monospecific section Rhipocrambe Svent.) is considered to comprise 14 species, all endemic to Macaronesian archipelagoes: 13 in the Canary Islands and one in the Madeira Islands. Crambe feuilleei A. Santos and C. gomerae subsp. hirsuta Prina are described here, C. fruticosa subsp. pinnatifida (Lowe) Prina & Mart.-Laborde is proposed as a new status, and a key for the identification of all taxa, as well as maps with localities of collection, are provided.  © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 156 , 291–304.     

Teucrium francoi M. Seq., Capelo, J.C. Costa & R. Jardim, a new species of Teucrium gr. scorodonia (Lamiceae) from Madeira

The species formerly recognized as Teucrium scorodonia in Madeira is here described as new: Teucrium francoi M. Seq., Capelo, J.C. Costa & R. Jardim. Morphologically close to species of Teucrium gr. scorodonia [ T. scorodonia L., T. pseudoscorodonia Desf., T. siculum (Raf.) Guss. and T. kotschyanum Poech], it exhibits, nonetheless, some distinct diagnostic characters. The indumentum density and type of hairs of T. francoi are clearly distinct from those of related species, as are the shape and dimensions of the leaves and bracts, calyx, and corolla, which are all taken as taxonomically significant diagnostic features. A diagnosis and a distribution map are presented for this new species. Morphology, ecology, biogeography, and conservation issues are discussed. Teucrium francoi , which is an endemic from Madeira (Portugal), is to be found mostly in the scope of the association Teucrio francoi–Origanetum virentis J.C. Costa, Capelo, Jardim, Sequeira, Lousã & Rivas-Martínez, but also occurs in somewhat humid habitats, such as open stands of Rosa mandonii Déségl. associated with small streams.  © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society , 2008, 156 , 639–647.     

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 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.     

Chloroplast DNA evidence for the roles of island colonization and extinction in Tolpis (Asteraceae: Lactuceae)

Tolpis consists of ～13 species native to Africa, Europe, and Macaronesia, with at least one species endemic to each of the four major archipelagos of the Azores, Madeira Islands, Canary Islands, and Cape Verde Islands. All but two of these species develop woody stems by maturity. Chloroplast DNA restriction site variation was analyzed for all species of Tolpis and four outgroups in order to understand the patterns of island colonization and evolution of woodiness in this genus. Parsimony analyses revealed a strongly supported monophyletic Tolpis. Within the genus, the following three well-supported groups were detected: all species from the Canary Islands and Cape Verde Islands, both Azorean species, and both continental species. The Canary Island/Cape Verde clade was sister to the two continental species, and the Azorean clade was sister to this group. The two Madeiran species of Tolpis occupied the basalmost positions within the genus. When biogeography was mapped onto this phylogeny, nine equally parsimonious reconstructions (five steps each) of dispersal history were detected, which fell into two groups: eight reconstructions implied that Tolpis colonized Madeira from the continent, followed by continental extinction and subsequent continental recolonization, while one reconstruction implied that Tolpis colonized Macaronesia four times. Two of the reconstructions involving continental extinction required the least amount of overall dispersal distance. The cpDNA phylogeny also suggests that woodiness arose in the common ancestor of all extant Tolpis, followed by two independent reversals to an herbaceous habit. Assuming that one of the eight reconstructions favoring continental extinction and recolonization is true, our results suggest that Tolpis may represent the first documented example of a woody plant group in Macaronesia that has recolonized the mainland in herbaceous form.     

Holcus azoricus M. Seq. & Castrov. (Poaceae), a new species from the Azores Islands

A new species of Holcus L. (Poaceae), endemic to the Azores archipelago (Portugal), is described. The vegetative and reproductive structures were studied. The diagnostic characters were compared with those of closely related species. New chromosome counts in Holcus azoricus M. Seq. & Castrov. (2 n  = 35) and H. rigidus Hochst. (2 n  = 28) are included. A possible hybrid origin is hypothesized; the potential parents are H. lanatus L. and H. rigidus .  © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 154 , 259–267.     

Population dynamics of the Mexican cycad Dioon edule Lindl. (Zamiaceae): life history stages and management impact

The demographic dynamics of three populations of Dioon edule Lindl. (Zamiaceae) were studied in a fragmented landscape using projection matrix modelling. Compared with other plant species, D. edule behaves like a tree life-form species. Density and spatial distribution patterns varied among populations according to models for animal-dispersed tree species. In all scenarios, λ was most sensitive to changes in abundance of adult plants. The elasticity reproductive component (F) for the three populations was zero and stasis values (L) were higher, this being a function of the permanence of non-reproductive individuals. It was detected that disturbance influences the population dynamics of D. edule as a function of adult plant persistence. This observation suggests that the conservation of adult plants is critical for D. edule and perhaps for all cycads species. Adult plant decapitation should be halted at the 'Monte Oscuro' population, subjected to sustainable management since 1990, if higher seed production is needed in rural nurseries.  © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society , 2008, 157 , 381–391.     

A taxonomic revision of the genus Flagenium Baill. (Rubiaceae–Octotropideae)

A taxonomic revision of the genus Flagenium Baill. is presented. Flagenium is endemic to Madagascar and comprises six species; three new species are described here ( F. farafanganensis , F. petrikensis , and F. pedunculatum ) and one species ( F. arboreum ) is transferred into synonymy. Each species is fully described, and summaries of distribution, habitat and ecology, and phenology are given; conservation assessments are provided for each species. Flagenium is characterized by having ovaries with at least two erect and two pendulous ovules per locule, which, depending on the species, can display an additional two to four horizontal ovules per locule arranged between the uppermost and lowermost ovules. In addition, Flagenium has a longitudinally ten-ribbed fruit. These features are potentially unique within the Octotropideae.  © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 155 , 557–570.     

Evolution of the limpet Patella candei d'Orbigny (Mollusca, Patellidae) in Atlantic archipelagos: human intervention and natural processes

The genetic and morphological structure of Patella candei in the Macaronesian Islands were studied by allozyme electrophoresis and multivariate analysis (canonical discriminant analysis), respectively. Sixteen enzymes, yielding 21 resolvable loci were analysed for all populations using the BIOSYS-1 program. A disjunct distribution of genetically similar populations from the Azores and Selvagens Islands ( P.c. gomesii – P.c. candei ) was found, which showed two diagnostic loci with P.c. ordinaria from Madeira. Patella c. crenata from the Canaries showed an intermediate composition of 92% P.c. ordinaria and 8% P.c. gomesii–P.c. candei . Hypotheses are presented to explain the evolution of the genetic and morphological structure of P.c. candei in the Macaronesian Islands, including the interaction of natural processes and human intervention. Patella c. candei is considered to represent the ancestral form. An extinction or near extinction event may have happened in Madeira after which P.c. ordinaria arose, carrying only a small part of the diversity of the original form, which evolved in isolation. The ancestral form, P.c. candei , was depleted by human extraction from high levels of the shore in the Azores and Canaries. Patella c. gomesii , from the Azores evolved by phyletic evolution, colonizing low levels of the shore, leaving only a relict population in the Selvagens Islands, that remained almost free of human exploitation. Patella c. crenata is a hybrid with a high degree of introgression to P.c. ordinaria , which is maintained by the forces of human extraction at high-tide levels and by intraspecific competition at low-tide levels.  © 2002 The Linnean Society of London, Biological Journal of the Linnean Society , 2002, 77 , 341−353.     

Do chromosomal hybrids necessarily suffer from developmental instability?

The role of chromosomal rearrangements in disturbing reproduction in hybrids between karyotypically differentiated groups is fairly well documented. However, the effect of chromosomal changes at other phenotypic levels is rarely considered. In Tunisia, natural chromosomal hybrids of the house mouse exhibit developmental instability, suggesting that a high karyotypic heterozygosity might also affect developmental processes. If this is true, we predict that, in this species, developmental instability should arise in hybrids between any populations with a high chromosomal differentiation. To test this hypothesis, we compare the results obtained in Tunisian mice with those obtained in the present analysis on Madeiran mice. Both systems of races have similar levels of chromosomal differentiation (nine Robertsonian fusions). Unlike Tunisian mice, hybrids in Madeira display a similar level of developmental instability as parental groups. This indicates that structural heterozygosity per se does not necessarily impair developmental stability. It further suggests that chromosomal fusions are not all equivalent in their phenotypic effects, and that the identity of each fusion should be taken into account.  © 2006 The Linnean Society of London, Biological Journal of the Linnean Society , 2006, 88 , 33–43.     

Genetic characterization of hybridization between the New Zealand everlastings Helichrysum lanceolatum and Anaphalioides bellidioides (Asteraceae: Gnaphalieae)

Intergeneric hybridization between the endemic New Zealand species Helichrysum lanceolatum and Anaphalioides bellidioides (Asteraceae: Gnaphalieae) at two Banks Peninsula populations was investigated by DNA sequencing and amplified fragment length polymorphism fingerprinting. Crosses in both directions have contributed to the generation of the F1 hybrids, but in the study season hybridization was far more common with H. lanceolatum as the maternal parent. F1 hybrids have reduced, but considerable, fertility and seed collected from them includes back-crosses. Two hybrid plants sampled from the wild appear to be back-crosses to H. lanceolatum. Despite back-crossing, introgression was not demonstrated and is at most limited in scope. These results also corroborate important roles for small population size and rarity in the formation of hybrid lineages in New Zealand's everlastings.  © 2007 Landcare Research New Zealand Ltd. Journal compilation © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 154 , 89–98.     

Mitochondrial DNA phylogenetic analysis of the genus Laparocerus (Coleoptera, Curculionidae, Entiminae). I. The Madeiran clade

Laparocerus are plant‐chewing flightless weevils distributed on oceanic islands in Macaronesia, with a single species in Morocco. The genus has a complicated taxonomic history with several subgenera described. To assist in a taxonomical revision of the group, a molecular study was undertaken. In this first contribution, the species from the Azores and Madeira archipelagos are studied together with representatives of subgenera from the Canary Islands and the single known continental species (46 OTUs). Phylogenetic analyses are based on sequence data from mitochondrial cytochrome oxidase II (COII) and the ribosomal 16S ribosomal RNA (16S rRNA) genes (combined data set 1023 bp), with additional data from the nuclear elongation factor 1α (EF‐1α) for some selected species. Maximum likelihood (ML) and Bayesian analyses show that all Madeiran species are monophyletic and form a monophyletic group with the Afro‐Canarian samples. Species of the genus Lichenophagus appear within the Madeiran and Canarian Laparocerus clades, but separated in accordance with their respective island origin. Thus, Lichenophagus is here restricted to Madeiran species and proposed as subgenus (status novo) of Laparocerus. Conversely, the Laparocerus subgenus Drouetius from the Azores is revealed to be a separate and distant outgroup, in agreement with its morphological distinctiveness, deserving an independent genus status. Internal relationships within the Madeiran clade are discussed and compared with morphologically defined species groups. The Madeiran monotypic subgenus Cyphoscelis is not supported by the genetic data and synonymized (nov. syn.) with Laparocerus. Subgenera Laparocerus and Atlantis prove to be polyphyletic. Consequently a restriction to monophyletic and morphologically congruent clades is proposed. A cryptic species vicariant of Laparocerus morio was detected and recognized as L. chaoensis, status novo. Other cases of discrepancy between the genetic results and the traditional taxonomy are discussed in detail in the light of mitochondrial introgression, incomplete lineage sorting or poor taxonomy hypotheses.