Microsatellite primers for the four Galápagos mockingbird species (Mimus parvulus, Mimus macdonaldi, Mimus melanotis and Mimus trifasciatus)

Nineteen di- and tetranucleotide and one trinucleotide microsatellite DNA markers were isolated from the Galápagos mockingbird (Mimus parvulus) and tested for cross-species amplification in the other three mockingbird species in the Galápagos. In addition, primers for two microsatellite loci previously developed for Mimus polyglottos were redesigned to obtain shorter amplification fragments. The number of alleles per locus and species ranged from 1 to 8, and expected heterozygosity varied from 0.0 to 0.809. These microsatellite markers will be useful to study levels of inbreeding in different island populations.     

Microsatellite markers isolated from the flightless cormorant (Phalacrocorax harrisi)

Eight polymorphic microsatellite DNA loci were isolated from the flightless cormorant (Phalacrocorax harrisi) for future population genetic studies. Genetic variability was assessed using at least 38 individuals from two populations. Allele numbers ranged from three to nine per locus. Mean observed heterozygosity varied from 0.27 to 0.78. No locus deviated from Hardy-Weinberg (HW) or linkage equilibria in either population. The high levels of detected polymorphism indicate the utility of these markers for population genetic studies of this Galápagos species.     

Development of 10 highly-polymorphic microsatellite markers in the vulnerable Galápagos land iguanas (genus Conolophus)

The two species of Galápagos land iguanas (Conolophus subcristatus and C. pallidus) are listed as 'vulnerable' species by the International Union for the Conservation of Nature (IUCN Red List; http://www.iucnredlist.org). Here, we report on the isolation and characterization of 10 microsatellite markers using 562 individuals sampled on all Galápagos islands where Conolophus species occur today. We show that these 10 loci are highly polymorphic and display diagnostic alleles for five out of the six island populations. These markers will be useful for Conolophus population genetic analyses as well as for guiding ongoing captive breeding programmes.     

Understanding the colonization history of the Galápagos flycatcher (Myiarchus magnirostris)

The Galápagos archipelago has never been connected to any continental land masses, so it is of interest to know the colonization and diversification history of its endemic species. We analyzed the phylogenetic placement of the endemic Galápagos flycatcher, M. magnirostris, within Myiarchus by using the genes ND2 and cytb (1970 bp) to compare 16 of the 22 species that comprise this genus. We also analyzed variability in cytb sequences from 154 M. magnirostris individuals captured on seven Galápagos islands. Our phylogenetic analyses recovered the two main Myiarchus clades that had been described by previous genetic, morphological, and vocal analyses. M. magnirostris is monophyletic and its closest living relative is M. tyrannulus from Mexico and Central America. The average age for the split node between these two groups was approximately 850,000 years (95% C.I. 630,735-1,087,557). M. tyrannulus, M. nugator, M. nuttingi, M. sagrae, and M. stolidus are not monophyletic species. Within M. magnirostris itself, we found low nucleotide and haplotype diversities (π=0.0009 and h=0.4913, respectively) and a high genetic structure among populations. We also detected a star-shaped haplotype network and significantly negative values for Tajima's D and Fu's Fs for this species. Our results suggest that M. magnirostris originated from a single colonization event and had a recent population expansion in the Galápagos archipelago.     

Origin and population history of a recent colonizer, the yellow warbler in Galápagos and Cocos Islands

The faunas associated with oceanic islands provide exceptional examples with which to examine the dispersal abilities of different taxa and test the relative contribution of selective and neutral processes in evolution. We examine the patterns of recent differentiation and the relative roles of gene flow and selection in genetic and morphological variation in the yellow warbler (Dendroica petechia aureola) from the Galápagos and Cocos Islands. Our analyses suggest aureola diverged from Central American lineages colonizing the Galápagos and Cocos Islands recently, likely less than 300 000 years ago. Within the Galápagos, patterns of genetic variation in microsatellite and mitochondrial markers suggest early stages of diversification. No intra-island patterns of morphological variation were found, even across steep ecological gradients, suggesting that either (i) high levels of gene flow may be homogenizing the effects of selection, (ii) populations may not have had enough time to accumulate the differences in morphological traits, or (iii) yellow warblers show lower levels of 'evolvability' than some other Galápagos species. By examining genetic data and morphological variation, our results provide new insight into the microevolutionary processes driving the patterns of variation.     

Characterization of eight microsatellite loci in the Galápagos endemic land snail Bulimulus reibischi, and their cross-species amplification

Variation in and amplification conditions for eight polymorphic microsatellite loci initially identified from Bulimulus akamatus, a pulmonate land snail from Galápagos, are described. Intraspecific polymorphism and heterozygosity of the eight markers were studied in 19 populations of Bulimulus reibischi, a closely related species of B. akamatus. Furthermore, the eight loci were also cross-amplified in six other closely related bulimulid species. The number of alleles across populations of B. reibischi at six loci is moderate (three to 10), but considerable for two other loci (19 and 20). There is no strong evidence for linkage among any of the loci examined.     

Wrasses of the Galápagos Islands, with the description of a new deepwater species of Halichoeres (Perciformes: Labridae)

Halichoeres raisneri, new species, is described from three specimens captured by the Johnson Sea Link submersible at 114-125 m off Wolf Island, Galápagos. Distinctive features of the new species include a dorsally projecting fleshy flap along the posterior three-quarters of the upper lip and the absence of a canine tooth at the corner of the upper jaw. The body color of freshly caught females is pale pink with two yellow stripes and five prominent pink spots above the uppermost stripe. Similarities between the new species and other labrids are discussed, and a key to the 16 nominal species of Labridae known from the Galápagos Islands is provided. Decodon melasma is recorded from the Archipelago for the first time.     

Patterns of long-distance dispersal in Tiquilia subg. Tiquilia (Boraginaceae): implications for the origins of amphitropical disjuncts and Galapagos Islands endemics

Plant biogeographers have long argued whether plant disjunctions result from vicariance or dispersal. One of the classic patterns of plant disjunction involves New World amphitropical disjuncts, as exemplified by Tiquilia subg. Tiquilia (Boraginaceae). Subgenus Tiquilia forms a heterogeneous group of ~20 species that is amphitropically distributed in the deserts of North and South America, with four taxa endemic to the Galápagos Islands. The current study reconstructs the biogeographic history of subg. Tiquilia in order to explore the origins of New World amphitropical disjunction and of Galápagos endemism. A strongly supported phylogeny of the subgenus is estimated using sequence data from matK, ndhF, rps16, ITS, and waxy. Biogeographic analyses using combined and individual marker data sets reveal a complex history of long-distance dispersal in subg. Tiquilia. Biogeographic reconstructions imply a North American origin of the subgenus and its three major lineages and require at least four long-distance dispersal events to explain its current distribution. The South American taxa of subg. Tiquilia result from three independent and nonsimultaneous colonization events, while the monophyly and continental origins of the Galápagos endemics are unresolved. This study contributes to a growing body of evidence that intercontinental dispersal has been more common than previously realized.     

Colonization and diversification of Galápagos terrestrial fauna: a phylogenetic and biogeographical synthesis

Remote oceanic islands have long been recognized as natural models for the study of evolutionary processes involved in diversification. Their remoteness provides opportunities for isolation and divergence of populations, which make islands remarkable settings for the study of diversification. Groups of islands may share a relatively similar geological history and comparable climate, but their inhabitants experience subtly different environments and have distinct evolutionary histories, offering the potential for comparative studies. A range of organisms have colonized the Galápagos Islands, and various lineages have radiated throughout the archipelago to form unique assemblages. This review pays particular attention to molecular phylogenetic studies of Galápagos terrestrial fauna. We find that most of the Galápagos terrestrial fauna have diversified in parallel to the geological formation of the islands. Lineages have occasionally diversified within islands, and the clearest cases occur in taxa with very low vagility and on large islands with diverse habitats. Ecology and habitat specialization appear to be critical in speciation both within and between islands. Although the number of phylogenetic studies is continuously increasing, studies of natural history, ecology, evolution and behaviour are essential to completely reveal how diversification proceeded on these islands.     

Notes on Galápagos grenadiers (Pisces, Gadiformes, Macrouridae), with the description of a new species of Coryphaenoides

Two unusual specimens of the grenadier genus Coryphaenoides were collected by the deep-submersible vehicle Johnson Sea-Link off the Galápagos. Unlike any other member of the genus, the snout in these specimens was rounded, non-protruding, naked anteriorly and ventrally, with no tubercular scales marking the terminal and lateral angles. They are herein described as Coryphaenoides gypsochilus. Additional specimens of grenadiers were procured by the Johnson Sea-Link, including the second and third specimens of Nezumia ventralis and the first record of Caelorinchus canus from these waters. Three species and one subspecies of Galápagos grenadiers are endemic.     

Status of the eastern Pacific agujon needlefish Tylosurus pacificus (Steindachner, 1876) (Beloniformes: Belonidae)

Tylosurus pacificus (Steindachner, 1876) is confirmed to have full species rank based on: 1) sympatry with T. acus melanotus at Isla Gorgona and in Panamá; 2) level of morphological differentiation in numbers of vertebrae, dorsal and anal fin rays; and 3) level of mtDNA differentiation. The eastern Pacific agujon needlefish is found from the Gulf of California, Mexico, to Peru, including the Galápagos Islands.     

Redescription of Symphurus diabolicus, a poorly-known, deep-sea tonguefish (Pleuronectiformes: Cynoglossidae) from the Galápagos Archipelago

Symphurus diabolicus, previously known only from the holotype collected in 501 m west of Isla San Cristobal (Chatham Island), Galápagos Archipelago, is re-described based on the holotype (112.6 mm SL) and 19 additional specimens (61.1-123.5 mm SL) recently collected from deep waters around the Galápagos Archipelago. Symphurus diabolicus is characterized by: an elongate body; narrow head with pointed snout; 1-3-2 ID pattern; 106-110 dorsal-fin rays; 89-96 anal-fin rays; 12 caudal-fin rays; 57-59 total vertebrae; 5 hypurals; extremely small scales; no pupillary operculum; large, prominent eyes, with migrated eye near dorsal margin of head; relatively short postorbital head length; relatively long snout and predorsal lengths; black peritoneum visible through abdominal wall on both sides of body; uniform olive green to dark brown ocular-side coloration with series of prominent, darker brown, elliptical to rectangular, blotches (not usually forming crossbands) along body at bases of dorsal and anal fins; and uniformly whitish or light yellow blind side. Symphurus diabolicus appears to be endemic to the Galápagos Archipelago, and is relatively common (captured at 16 different localities) at depths of 308 to 757 m (observed as shallow as 245 m) in this region. Examination of this expanded series of specimens confirms the validity of S. diabolicus and provides characters to distinguish it from S. microlepis Garman, a similar species known only from the holotype taken at approximately 530 m off Pacific Panama.     

Characterization of canarypox-like viruses infecting endemic birds in the Galápagos Islands

The presence of avian pox in endemic birds in the Galápagos Islands has led to concern that the health of these birds may be threatened by avipoxvirus introduction by domestic birds. We describe here a simple polymerase chain reaction-based method for identification and discrimination of avipoxvirus strains similar to the fowlpox or canarypox viruses. This method, in conjunction with DNA sequencing of two polymerase chain reaction-amplified loci totaling about 800 bp, was used to identify two avipoxvirus strains, Gal1 and Gal2, in pox lesions from yellow warblers (Dendroica petechia), finches (Geospiza spp.), and Galápagos mockingbirds (Nesomimus parvulus) from the inhabited islands of Santa Cruz and Isabela. Both strains were found in all three passerine taxa, and sequences from both strains were less than 5% different from each other and from canarypox virus. In contrast, chickens in Galápagos were infected with a virus that appears to be identical in sequence to the characterized fowlpox virus and about 30% different from the canarypox/Galápagos group viruses in the regions sequenced. These results indicate the presence of canarypox-like viruses in endemic passerine birds that are distinct from the fowlpox virus infecting chickens on Galápagos. Alignment of the sequence of a 5.9-kb region of the genome revealed that sequence identities among Gal1, Gal2, and canarypox viruses were clustered in discrete regions. This indicates that recombination between poxvirus strains in combination with mutation led to the canarypox-like viruses that are now prevalent in the Galápagos.     

Phylogeny of Nolana (Solanaceae) of the Atacama and Peruvian deserts inferred from sequences of four plastid markers and the nuclear LEAFY second intron

The phylogeny of Nolana (Solanaceae), a genus primarily distributed in the coastal Atacama and Peruvian deserts with a few species in the Andes and one species endemic to the Galápagos Islands, was reconstructed using sequences of four plastid regions (ndhF, psbA-trnH, rps16-trnK and trnC-psbM) and the nuclear LEAFY second intron. The monophyly of Nolana was strongly supported by all molecular data. The LEAFY data suggested that the Chilean species, including Nolana sessiliflora, the N. acuminata group and at least some members of the Alona group, are basally diverged, supporting the Chilean origin of the genus. Three well-supported clades in the LEAFY tree were corroborated by the SINE (short interspersed elements) or SINE-like insertions. Taxa from Peru are grouped roughly into two clades. Nolana galapagensis from the Galápagos Island is most likely to have derived from a Peruvian ancestor. The monophyly of the morphologically well-diagnosed Nolana acuminata group (N. acuminata, N. baccata, N. paradoxa, N. parviflora, N. pterocarpa, N. rupicola and N. elegans) was supported by both plastid and LEAFY data. Incongruence between the plastid and the LEAFY data was detected concerning primarily the positions of N. sessiliflora, N. galapagensis, taxa of the Alona group and the two Peruvian clades. Such incongruence may be due to reticulate evolution or in some cases lineage sorting of plastid DNA. Incongruence between our previous GBSSI trees and the plastid-LEAFY trees was also detected concerning two well-supported major clades in the GBSSI tree. Duplication of the GBSSI gene may have contributed to this incongruence.     

Causes of mortality of wild birds submitted to the Charles Darwin Research Station, Santa Cruz, Galapagos, Ecuador from 2002-2004

Necropsy findings were reviewed from wild birds submitted to the Charles Darwin Research Station, Santa Cruz Island, Galápagos Archipelago between 2004 and 2006. One hundred and ninety cases from 27 different species were submitted, and 178 of these cases were evaluated grossly or histologically. Trauma and trauma-related deaths (n=141) dominated necropsy submissions. Infectious causes of avian mortality included myiasis due to Philornis sp. (n=6), avian pox (n=1), and schistosomosis (n=1).     

Disruptive selection in a bimodal population of Darwin's finches

A key part of the ecological theory of adaptive radiation is disruptive selection during periods of sympatry. Some insight into this process might be gained by studying populations that are bimodal for dual-context traits, i.e. those showing adaptive divergence and also contributing to reproductive isolation. A population meeting these criteria is the medium ground finch (Geospiza fortis) of El Garrapatero, Santa Cruz Island, Galápagos. We examined patterns of selection in this population by relating individual beak sizes to interannual recaptures during a prolonged drought. Supporting the theory, disruptive selection was strong between the two beak size modes. We also found some evidence of selection against individuals with the largest and smallest beak sizes, perhaps owing to competition with other species or to gaps in the underlying resource distribution. Selection may thus simultaneously maintain the current bimodality while also constraining further divergence. Spatial and temporal variation in G. fortis bimodality suggests a dynamic tug of war among factors such as selection and assortative mating, which may alternatively promote or constrain divergence during adaptive radiation.     

Inter-population variation of carotenoids in Galápagos land iguanas (Conolophus subcristatus)

Carotenoids have received much attention from biologists because of their ecological and evolutionary implications in vertebrate biology. We sampled Galápagos land iguanas (Conolophus subcristatus) to investigate the types and levels of blood carotenoids and the possible factors affecting inter-population variation. Blood samples were collected from populations from three islands within the species natural range (Santa Cruz, Isabela, and Fernandina) and one translocated population (Venecia). Lutein and zeaxanthin were the predominant carotenoids found in the serum. In addition, two metabolically modified carotenoids (anhydrolutein and 3'-dehydrolutein) were also identified. Differences in the carotenoid types were not related to sex or locality. Instead, carotenoid concentration varied across the localities, it was higher in females, and it was positively correlated to an index of body condition. Our results suggest a possible sex-related physiological role of xanthophylls in land iguanas. The variation in the overall carotenoid concentration between populations seems to be related to the differences in local abundance and type of food within and between islands.     

Relationships, origin, and diversity of Galapagos tomatoes: implications for the conservation of natural populations

Endemic Galápagos tomatoes (Lycopersicon cheesmanii) are of great value for cultivated tomato (L. esculentum) breeding, and therefore their conservation is of significance. Although within L. cheesmanii there is heterogeneity for many traits and formal infraspecific classification is not justified, here we distinguish three forms, without taxonomic significance, of L. cheesmanii that are of interest to breeders because of their distinctive morphology and habitat preferences: L. cheesmanii 'short' (one- to two-pinnate leaves, short internodes, and coastal habitats), L. cheesmanii 'long' (one- to two-pinnate leaves, long internodes, and inland habitats), and L. cheesmanii forma minor (three- to four-pinnate leaves, short internodes, and coastal habitats). In a recent survey of tomato populations in the Galápagos Islands, we found that several populations of L. cheesmanii reported 30-50 years earlier had disappeared, mostly as a consequence of human activity. In addition, a previously unreported invasive wild red-fruited form, which we named L. esculentum 'Gal cer,' was found on the island of Santa Cruz. The total diversity (estimated with amplified fragment length polymorphisms [AFLPs]) within L. cheesmanii (H(T) = 0.051) is almost as high as that for the mainland wild species L. pimpinellifolium (H(T) = 0.072). Lycopersicon esculentum 'Gal cer,' on the other hand, has a much lower diversity (H(T) = 0.014). Comparison of AFLP fragments shared by L. esculentum 'Gal cer' with other species showed that it is closely related to weedy tomato L. esculentum var. cerasiforme and, therefore, likely of recent origin. Genetic differentiation among the three native L. cheesmanii forms is low (G(ST) = 0.235), indicating that they share a common genetic background. Nonetheless, L. cheesmanii 'short' is about twice as diverse as L. cheesmanii 'long' or L. cheesmanii f. minor. UPGMA cluster and principal components analysis distinguish four groups within Eulycopersicon: L. pimpinellifolium, cultivated L. esculentum, L. esculentum var. cerasiforme including L. esculentum 'Gal cer,' and L. cheesmanii. The geographic distance and genetic distance in the wild forms of Galápagos tomatoes were not correlated. Apart from the pressure of humans, some native L. cheesmanii populations, especially L. cheesmanii 'long,' might be displaced by invasive L. esculentum 'Gal cer' because they share a similar habitat. We did not find evidence of intercrossing of L. cheesmanii with introduced L. esculentum, but occasional hybridization that contributes to loss of genetic integrity of L. cheesmanii cannot be ruled out. Establishment of reserves of L. cheesmanii to protect this species from introduced herbivorous animals and from hybridization with L. esculentum 'Gal cer' would help to conserve L. cheesmanii. Furthermore, accessions collected by C. M. Rick and others in the 1950s-1970s and now stored in germplasm banks could be used to reinstate some extinct populations.     

Isolation and characterization of microsatellite loci in the Galápagos Opuntia weevil Gerstaeckeria galapagoensis (Coleoptera,Curculionidae)

Five microsatellite loci were isolated from the Galápagos weevil Gerstaeckeria galapagoensis. Polymorphism ranged from two to seven alleles, and observed and expected heterozygosities ranged from 0.286 to 0.917 and 0.254 to 0.683, respectively.     

Isolation and characterization of microsatellite loci from Galápagos lava lizards (Microlophus spp.)

We describe the isolation of microsatellite loci from Galápagos lava lizards (Microlophus spp.) using an enriched genomic library. Twelve loci that are polymorphic among six populations from two species are described. Characterization of these loci in 20 individuals within one population (Isla Plaza Sur) showed seven to be polymorphic with 3–11 alleles. Heterozygosities within this population were high (0.32–0.90) and did not deviate from Hardy–Weinberg expectations. We suggest that these markers will be useful in studies of population differentiation within and among islands across the Galápagos archipelago.