Pedro Oromí

Colonization and diversification: towards a phylogeographic synthesis for the Canary Islands.

Recently, the Canary Islands have become a focus for studies of the colonization and the diversification of different organisms. Some authors have considered Canarian endemisms as relicts of Tertiary origin, but new molecular data suggest a general pattern of continental dispersion followed by in situ speciation. Recent phylogeographic studies are revealing variants of the simple stepping-stone colonization model that seems to hold for many Hawaiian groups. Many factors can generate deviations from such a pattern: the stochastic nature of colonization, competitive exclusion, phylogenetic constraints on adaptive evolution and extinction. An understanding of island colonization and diversification can best be developed from an ecosystem level synthesis as more data for the Canarian archipelago come to hand.

Mitochondrial DNA Phylogeny and Sequential Colonization of Canary Islands by Darkling Beetles of the Genus Pimelia (Tenebrionidae)

Fifteen species of the darkling beetle genus Pimelia (Tenebrionidae: Coleoptera) have been sequenced for a 365 b. p. portion of the mitochondrial Cytochrome Oxidase I gene. Thirteen of these are endemic species inhabiting the Canarian archipelago in the Atlantic and the other two are continental conspecifics. This data set has been phylogenetically analysed by maximum parsimony and distance approaches and the resulting trees used to deduce sequential interisland colonization. This suggests patterns compatible with the geological dating of the islands, but with increasing uncertainty when older events are considered. A colonization sequence from Fuerteventura to Tenerife followed by Tenerife to Gran Canaria and La Gomera, and from the latter to La Palma and then to El Hierro is proposed for the genus. A relatively recent secondary colonization from Gran Canaria to Gomera is deduced.

Phylogeny of the genus Hegeter (Tenebrionidae, Coleoptera) and its colonization of the Canary Islands deduced from Cytochrome Oxidase I mitochondrial DNA sequences

The genus Hegeter comprises 23 species of darkling beetles (Tenebrionidae) endemic to the Macaronesian archipelagos, with 21 of them exclusive to the Canary Islands. We have sequenced 438 bp of the mitochondrial Cytochrome Oxidase I gene in 17 species (24 taxa) of Canarian Hegeter. Estimates of nucleotide composition, transition/transversion ratios and nucleotide change frequencies are very similar to those found in another tenebrionid Canarian genus Pimelia, indicating that similar molecular mechanisms are driving the sequence evolution. The sequence variation found allows phylogenetic analyses of the genus and the deduction of colonization patterns. These involve sequential island invasion with more rapid establishment and radiation than found in the related beetles of the genus Pimelia.

DIVERSIFICATION OF THE FOREST BEETLE GENUS TARPHIUS ON THE CANARY ISLANDS, AND THE EVOLUTIONARY ORIGINS OF ISLAND ENDEMICS

Abstract The flightless beetle genus Tarphius Erichson (Coleoptera: Colydiidae) is a distinctive element of the betle fauna of the Canary Islands with 29 species distributed across the five western islands. The majority of Tarphius species are rare and inimately associated with the monteverde forest and only two species occurr on more than one island. It this study we investigate the phylogeography of the Canary Island Tarphius, and their relationship to Tarphius from the more northerly archipelagos of Madera and the Azores using Maximum parsimony and bayesian inference analysis of mitochondrial cytochrome oxidase I and II sequence data. We use geological datings for the Canary Islands, Azores, and Madeira to calibrate specific nodes of the tree for the estimation of divergence times using a penalized likelihood method. Data suggest that the Canary Island species assumblage is of some antiquity, however, much of this species diversity is relatively recent is origin. The phylogencetic relationships of species inhabiting the younger islands of EI hierro and LaPalma indicate that coloniztion events between islands have probably been a significant factor in the evolutionary history of the Canary Island species assemblage. A comparison of molecular phylogenetic studies of arthropods on the Canary Island suggests that, in the evolution of the arthropod species species community of an island, the origin of endemic species is initially the result of colonizing lineages differentiating from their source populations. However, as an island matures a greater proportion of endemic species originate from intra‐island speciation.

Colonization and diversification of the species Brachyderes rugatus (Coleoptera) on the Canary Islands: evidence from mitochondrial DNA COII gene sequences.

Abstract.— The genus Brachyderes Schönherr (Coleoptera: Curculionidae) is represented by the species B. rugatus Wollaston on the Canary Islands, with one subspecies on each of the islands of Gran Canaria, Tenerife, La Palma, and El Hierro. These four subspecies are associated with the endemic pine tree Pinus canariensis, and their distributions are broadly coincident. Eighty‐eight individual Canarian Brachyderes, sampled from across the distributions of each subspecies, have been sequenced for 570 bp of the mitochondrial DNA (mtDNA) cytochrome oxidase II gene (COII). No mitotypes are shared among islands. Both maximum‐likelihood and distance‐based phylogenetic analyses have shown that: Tenerife is composed of a single monophyletic clade of mitotypes, El Hierro is composed of a single monophyletic clade occurring within a larger clade comprising all the La Palma mitotypes, and the mitotypes of these three islands form a monophyletic group distinct from Gran Canaria. New methods for estimating divergence times without the assumption of rate constancy have been used to reconstruct the direction and approximate timing of colonizations among the islands. Colonization has occurred from older to progressionally younger islands, and these colonizations are estimated to have occurred less than 2.6 million years ago, although the timing of the initial colonization of the archipelago is not discernable. New methods for the estimation of diversification rates that use branching times as the analyzed variable have been applied to each island fauna. Hypothesized effects of different levels of recent volcanism among islands were not apparent. All islands exhibit a gradually decreasing rate of genetic diversification that is marked by periodic sudden changes in rate.

INTERPRETING COLONIZATION OF THE CALATHUS (COLEOPTERA: CARABIDAE) ON THE CANARY ISLANDS AND MADEIRA THROUGH THE APPLICATION OF THE PARAMETRIC BOOTSTRAP

The Canary Islands have proven to be an interesting archipelago for the phylogeographic study of colonization and diversification with a number of recent studies reporting evolutionary patterns and processes across a diversity of floral and faunal groups. The Canary Islands differ from the Hawaiian and Galapagos Islands by their close proximity to a continental land mass, being 110 km from the northwestern coast of Africa. This close proximity to a continent obviously increases the potential for colonization, and it can be expected that at the level of the genus some groups will be the result of more than one colonization. In this study we investigate the phylogeography of a group of carabid beetles from the genus Calathus on the Canary Islands and Madeira, located 450 km to the north of the Canaries and 650 km from the continent. The Calathus are well represented on these islands with a total of 29 species, and on the continent there are many more. Mitochondrial cytochrome oxidase I and II sequence data has been used to identify the phylogenetic relationships among the island species and a selection of continental species. Specific hypotheses of monophyly for the island fauna are tested with parametric bootstrap analysis. Data suggest that the Canary Islands have been colonized three times and Madeira twice. Four of these colonizations are of continental origin, but it is possible that one Madeiran clade may be monophyletic with a Canarian clade. The Calathus faunas of Tenerife and Madeira are recent in origin, similar to patterns previously reported for La Gomera, El Hierro, and Gran Canaria.

Radiation of the Spider Genus Dysdera (Araneae, Dysderidae) in the Canary Islands: Cladistic Assessment Based on Multiple Data Sets

The volcanic archipelago of the Canary Islands, 100 km off the northwestern coast of Africa, harbors 43 endemic species of the mostly circum‐Mediterranean spider genus Dysdera (Araneae, Dysderidae). This amounts to approximately one‐fourth of all known Dysdera species in an area that represents 0.1% of the range of the genus. In order to address the origin of this extraordinary number of endemic species, the phylogenetic relationships among all the endemic taxa and a sample of 27 continental species were reconstructed. A simultaneous cladistic analysis was performed on 66 morphological characters, 471 bp of the cytochrome oxidase I and 424 bp of the 16S rRNA mitochondrial genes. The preferred most parsimonious tree supports a single origin for most of the endemic species (84%), although this tree is ambiguous regarding the total number of overseas colonizations (allowing a minimum of two and a maximum of four colonization events). Our data suggest that the Canary Islands have been the source of the colonizers of some of the remaining Macaronesian archipelagoes (certainly for the Selvagem Islands and the Cape Verdes and possibly for Madeira); the Azores have been independently colonized by dysderids from the continent. The present study provides a phylogenetic framework for an exceptional case of insular species radiation, an essential tool for unraveling the factors that have promoted this amazing diversification. Species radiations in oceanic archipelagoes are excellent models for the study of speciation processes.

Mitochondrial DNA sequence variation and phylogeography of Pimelia darkling beetles on the Island of Tenerife (Canary Islands)

Four morphological taxa of the beetle genus Pimelia (Coleoptera, Tenebrionidae) are known to exist on the Atlantic island of Tenerife. We have obtained DNA sequences for 61 individuals from these taxa across the island for a 200 bp long fragment of the mitochondrial COI gene. In addition, a restriction site polymorphism in the nuclear rRNA ITS-1 sequence was identified and screened in a sample of these individuals using the enzyme Kpn2I. The results were analysed using approaches which allow inferences to be made about the population genetic structure and the mitochondrial genealogy of these closely related beetles. The mtDNA haplotype distribution and the estimates of sequence divergence revealed the presence of two ancient mtDNA lineages which coincide with the disjunct volcanic evolution of the island. The ITS-1 polymorphism was found to be diagnostic of these two lineages. However, the morphological and mitochondrial phylogenies were found to be discordant. We argue that this is possibly the result of rapid morphological change, produced by selection in different habitats, which has been recently superimposed on an older mitochondrial DNA divergence.

The subterranean fauna of a biodiversity hotspot region - Portugal: an overview and its conservation

INTRODUCTION Extensive biological studies have been made in the main karst areas around the world, namely in the eastern United States of America and in the region from the Pyrenees to Slovenia and the Dinaric karst (Culver et al., 2000; Culver & Pipan, 2009). Information about subterranean fauna in mainland Portugal is sparse and scattered along many publications mostly from the middle of the 20th century. The main thrust in the subterranean biology was given by the survey of caves made by Barros Machado during the 1940s, and by the prospection of well-dwelling crustaceans in the north of the country by researchers of the former Instituto de Zoologia “Dr. Augusto Nobre” from Porto University (Gama & Afonso, 1994). In addition, endogean habitats have been subject of considerable coleopterological

Under the volcano: phylogeography and evolution of the cave-dwelling Palmorchestia hypogaea (Amphipoda, Crustacea) at La Palma (Canary Islands).

BackgroundThe amphipod crustacean Palmorchestia hypogaea occurs only in La Palma (Canary Islands) and is one of the few terrestrial amphipods in the world that have adapted to a strictly troglobitic life in volcanic cave habitats. A surface-dwelling closely related species (Palmorchestia epigaea) lives in the humid laurel forest on the same island. Previous studies have suggested that an ancestral littoral Orchestia species colonized the humid forests of La Palma and that subsequent drought episodes in the Canaries reduced the distribution of P. epigaea favouring the colonization of lava tubes through an adaptive shift. This was followed by dispersal via the hypogean crevicular system.ResultsP. hypogaea and P. epigaea did not form reciprocally monophyletic mitochondrial DNA clades. They showed geographically highly structured and genetically divergent populations with current gene flow limited to geographically close surface locations. Coalescence times using Bayesian estimations assuming a non-correlated relaxed clock with a normal prior distribution of the age of La Palma, together with the lack of association of habitat type with ancestral and recent haplotypes, suggest that their adaptation to cave life is relatively ancient.ConclusionThe data gathered here provide evidence for multiple invasions of the volcanic cave systems that have acted as refuges. A re-evaluation of the taxonomic status of the extant species of Palmorchestia is needed, as the division of the two species by habitat and ecology is unnatural. The information obtained here, and that from previous studies on hypogean fauna, shows the importance of factors such as the uncoupling of morphological and genetic evolution, the role of climatic change and regressive evolution as key processes in leading to subterranean biodiversity.