Evolutionary relationships of Macaronesic Deschampsia Aveneae, Poaceae based on a morphological and molecular approaches.

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Publications

Colonization routes, microevolutionary genetic structure and conservation concerns in a remote widespread insular endemic grass: the case of the Azorean tussock grass Deschampsia foliosa

Publication . Moura, Mónica; Catalán, Pilar; Brehm, António; Sequeira, Miguel Menezes de

Population genetic structure and diversity and phylogeographical dispersal routes were assessed for the Azorean endemic grass Deschampsia foliosa using AFLP markers. This species occurs on seven islands in the archipelago and a sampling of populations from the three main geographical groups of islands was used, covering its known distribution. Principal coordinates analyses (PCoAs), Bayesian analyses and phylogenetic networks revealed different degrees of admixture for the central group (C) populations and a clear differentiation for the western group (W) and São Miguel island (in the eastern group, E) populations. The best K values corresponded to nine and 11 genetic groups, which were also confirmed by analysis of molecular variance. A low but significant correlation between genetic data and geography was observed, with most relevant barriers to gene flow generally placed between sub archipelagos. We suggest a west-to-east isolation by distance dispersal model across an island age continuum with Flores–Corvo (W) and Pico (C) at the extremes of the dispersal path. An alternative scenario, also supported by the genetic data, implies an initial colonization of São Jorge (C), dispersal within C and following bidirectional dispersal to the W and E. The phylogeographical framework detected might be related to island age and to highly destructive volcanic events, and it supports the occurrence of cryptic diversity within D. foliosa. Genetic diversity estimators were highest for Pico island populations (C), lowest for São Miguel (E) and Flores (W) populations, and more divergent for the Corvo population (W). Conservation measures should be taken to preserve the genetic structure found across sub-archipelagos and islands.

2019Journal article

Open access

Divergence and biogeography of the recently evolved Macaronesian red Festuca (Gramineae) species inferred from coalescence-based analyses

Publication . Diáz-Pérez, A. J.; Sequeira, Miguel; Santos-Guerra, A.; Catalán, P.

Studying the biogeography and the phylogeography of the endemic Macaronesian red Festuca species (Loliinae, Poaceae) is of prime interest in understanding the speciation and colonization patterns of recently evolved groups in oceanic archipelagos. Coales cence-based analyses of plastid trnLF sequences were employed to estimate evolutionary parameters and to test different species-history scenarios that model the pattern of species divergence. Bayesian IM estimates of species divergence times suggested that ancestral lineages of diploid Macaronesian and Iberian red fescues could have diverged between 1.2 and 1.57 Ma. When empirical data were compared to coalescence-based simulated distributions of discordance and p-distance statistics, two species-history models were chosen in which the first branching lineage derived in Canarian Festuca agustinii. Its sister lineage could have involved a recent polytomy leading to the Madeiran Festuca jubata, the Azorean Festuca francoi + Festuca petraea and the continental Festuca rivularis lineages (Canarian model) or the sequential branching of lineages leading to F. jubata and finally to the sister clades of F. rivularis and F. francoi + F. petraea (Sequential model). Nested clade phylogeographic analysis (NCPA) and a first adapted host–parasite co-evolutionary ParaFit method were used to detect the phylogeographic signal. NCPA inferred long-distance colonizations for the entire diploid red Festuca complex, but allopatric-fragmentation and isolation by-distance (IBD) patterns were inferred within archipelagos. In addition, the ParaFit method suggested a generalized pattern of a stepping-stone model at all hierarchical levels. Maximum-likelihood-based dispersal-extinction-cladogenesis (DEC) models were superimposed on the Sequential model species tree. The three-independent-colonization (3IC) model was the best supported biogeographic scenario, concurring with previous analysis based on multilocus AFLP data.

2012Journal article

Open access

Holcus pintodasilvae (Poaceae, Pooideae, Poeae), a new species from the Island of Madeira (Portugal), and notes on Macaronesian Holcus

Publication . Sequeira, Miguel Menezes de; Castroviejo, Santiago

A new species of Holcus L. (Poaceae), endemic to the island of Madeira (Portugal), is here described as H. pintodasilvae M. Seq. & Castrov. This new species is morphologically closely related to the Macaronesian endemics H. rigidus Hochst. ex Hochst. (Azores Archipelago) and H. mollis L. subsp. hierrensis Stierst. (El Hierro Island, in the Canary Islands) but differs by having the culm nodes light brown, the leaves with a glabrous sheath and subspreading lamina attenuated to an acuminate apex, the glumes blunt, shiny, glabrous (except in the minutely scabrous veins), the upper glume with proximal lateral veins, and the lemma of the upper floret with an awn ca. 4 mm, twice as long as the lemma. Chromosome counts in H. pintodasilvae are tetraploid (2 n = 28). Morphology, ecology, biogeog raphy, and conservation issues are discussed and related to other Macaronesian Holcus taxa. Holcus (totaling less than 20 individuals), and its IUCN conservation status is Critically Endangered (CR). A new specific status is proposed for H. mollis subsp. hierrensis, as H. hierrensis (Stierst.) Stierst. & M. Seq., based on its chromosome number and morphological identity.

2013Journal article

Open access

Karyological analysis of the five native Macaronesian Festuca (Gramineae) grasses supports a distinct diploid origin of two schizoendemic groups

Publication . Sequeira, Miguel Menezes de; Díaz-Pérez, Antonio; Santos-Guerra, Arnoldo; Viruel, Juan; Catalán, Pilar

Menezes de Sequeira, M., Díaz-Pérez, A., Santos-Guerra, A., Viruel, J. & Catalán, P. 2009. Karyological analysis of the five na tive Macaronesian Festuca (Gramineae) grasses supports a dis tinct diploid origin of two schizoendemic groups. Anales Jard. Bot. Madrid 66(1): 55-63. A karyological analysis has been conducted of all five native Macaronesian Festuca grasses belonging to fine-leaved F. subg. Festuca sect. Aulaxyper and broad-leaved F. subg. Drymanthele sect. Phaeochloa Loliinae lineages. Chromosomal analyses were made in 30 plants corresponding to 17 populations of the fine leaved F. agustinii, F. jubata, F. francoi and F. petraea and 2 pop ulations of the broad-leaved F. donax. All counts except one tetraploid count were diploids, showing 2n = 14 chromosomes. Diploidy was confirmed for the robust F. donax, nested within a clade of relict ancestral fescues as reported in recent phyloge netic studies, and was also found in the more slender F. agus tinii, F. jubata, F. francoi and F. petraea, which are basal to a re cently evolved clade of polyploid red fescues. Karyotypes of the two groups are however distinct, with broad-leaved F. donax showing larger and more regular chromosomes and all four fine-leaved taxa showing smaller and more irregular submeta centric chromosomes. Our karyological data indicate that these two groups of diploid fescues correspond to distinct schizoen demics which apparently originated at different times after in dependent continental colonizations of Macaronesia

2009Journal article

Open access

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

Publication . Díaz-Pérez, Antonio; Sequeira, Miguel; Santos-Guerra, Arnoldo; Catalán, Pilar

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 correla tions 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 geographi cally 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 eco logical 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 fa vored 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. [Bayesian genetic analyses; colonization of oceanic islands; dispersal models; Festuca sect. Aulaxyper; Macaronesia; phylogeography.]

2008Journal article

Open access