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631 results for “Galápagos”

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Data from: Lineage fusion in Galápagos giant tortoises

Although many classic radiations on islands are thought to be the result of repeated lineage splitting, the role of past fusion is rarely known because during these events, purebreds are rapidly replaced by a swarm of admixed individuals. Here we capture lineage fusion in action in a Galápagos giant tortoise species, Chelonoidis becki, from Wolf Volcano (Isabela Island). The long generation time of Galápagos tortoises and dense sampling (841 individuals) of genetic and demographic data were integral in detecting and characterizing this phenomenon. In C. becki we identified two genetically distinct, morphologically cryptic lineages. Historical reconstructions show that they colonized Wolf Volcano from Santiago Island in two temporally separated events, the first estimated to have occurred ~199 thousand years ago (KYA). Following arrival of the second wave of colonists, both lineages co-existed for approximately ~53 KY. Within that time they began fusing back together, as microsatellite data reveal widespread introgressive hybridization. Interestingly, greater mate selectivity seems to be exhibited by purebred females of one of the lineages. Forward-in-time simulations predict rapid extinction of the early arriving lineage. This study provides a rare example of reticulate evolution in action, and underscores the power of population genetics for understanding the past, present, and future consequences of evolutionary phenomena associated with lineage fusion.

opencc-zeroDec 2013View details →

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Data from: Genetic rediscovery of an 'extinct' Galápagos giant tortoise species

Genes from recently extinct species can live on in the genomes of extant individuals of mixed ancestry. Recently, Poulakakis et al. detected genetic signatures of the giant Galápagos tortoise once endemic to Floreana Island (Chelonoidis elephantopus) within eleven hybrid individuals of otherwise pure C. becki on Volcano Wolf, Isabela Island. Movement of tortoises among islands by pirate and whaling ships was not uncommon during the 1800's, representing a likely mechanism by which individuals from Floreana were translocated to northern Isabela, despite being presumed extinct soon after Charles Darwin's historic voyage to the Galápagos Islands in 1835. These eleven hybrid individuals with C. elephantopus ancestry were thought to be the last genetic vestiges of a unique evolutionary lineage in the wild. Here we report that reproductively mature purebred tortoises of the recently 'extinct' C. elephantopus from Floreana Island are very likely still alive today, as identified and tracked through the genetic footprints' left in the genomes of very recent hybrid offspring on Volcano Wolf, Isabela Island. If found, these purebred C. elephantopus individuals could constitute core founders of a captive breeding program directed towards resurrecting this species.

opencc-zeroDec 2011View details →

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Data from: Hybridization masks speciation in the evolutionary history of the Galápagos marine iguana

The effects of the direct interaction between hybridization and speciation—two major contrasting evolutionary processes—are poorly understood. We present here the evolutionary history of the Galápagos marine iguana (Amblyrhynchus cristatus) and reveal a case of incipient within-island speciation, which is paralleled by between-island hybridization. In-depth genome-wide analyses suggest that Amblyrhynchus diverged from its sister group, the Galápagos land iguanas, around 4.5 million years ago (Ma), but divergence among extant populations is exceedingly young (less than 50 000 years). Despite Amblyrhynchus appearing as a single long-branch species phylogenetically, we find strong population structure between islands, and one case of incipient speciation of sister lineages within the same island—ostensibly initiated by volcanic events. Hybridization between both lineages is exceedingly rare, yet frequent hybridization with migrants from nearby islands is evident. The contemporary snapshot provided by highly variable markers indicates that speciation events may have occurred throughout the evolutionary history of marine iguanas, though these events are not visible in the deeper phylogenetic trees. We hypothesize that the observed interplay of speciation and hybridization might be a mechanism by which local adaptations, generated by incipient speciation, can be absorbed into a common gene pool, thereby enhancing the evolutionary potential of the species as a whole.

opencc-zeroDec 2014View details →

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Data from: Genome-wide assessment of diversity and divergence among extant Galápagos giant tortoise species

Genome-wide assessments allow for fuller characterization of genetic diversity, finer-scale population delineation, and better detection of demographically significant units to guide conservation compared to those based on "traditional" markers. Galapagos giant tortoises (Chelonoidis spp.) have long provided a case study for how evolutionary genetics may be applied to advance species conservation. Ongoing efforts to bolster tortoise populations, which have declined by 90%, have been informed by analyses of mitochondrial DNA sequence and microsatellite genotypic data, but could benefit from genome-wide markers. Taking this next step, we used double-digest restriction-site associated DNA sequencing to collect genotypic data at >26,000 single nucleotide polymorphisms (SNPs) for 117 individuals representing all recognized extant Galapagos giant tortoise species. We then quantified genetic diversity, population structure, and compared results to estimates from mitochondrial DNA and microsatellite loci. Our analyses detected 12 genetic lineages concordant with the 11 named species as well as previously described structure within one species, C. becki. Furthermore, the SNPs provided increased resolution, detecting admixture in four individuals. SNP-based estimates of diversity and differentiation were significantly correlated with those derived from nuclear microsatellite loci and mitochondrial DNA sequences. The SNP toolkit presented here will serve as a resource for advancing efforts to understand tortoise evolution, species radiations, and aid conservation of the Galapagos tortoise species complex.

opencc-zeroDec 2017View details →

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Data from: Cultural turnover among Galápagos sperm whales

While populations may wax and wane, it is rare for an entire population to be replaced by a completely different set of individuals. We document the large-scale relocation of cultural groups of sperm whale off the Galápagos Islands, in which two sympatric vocal clans were entirely replaced by two different ones. Between 1985 and 1999, whales from two clans (called Regular and Plus-One) defined by cultural dialects in coda vocalizations were repeatedly photo-identified off Galápagos. Their occurrence in the area declined through the 1990s; by 2000, none remained. We reassessed Galápagos sperm whales in 2013–2014, identifying 463 new females. However, re-sighting rates were low, with no matches with the Galápagos 1985–1999 population, suggesting an eastward shift to coastal areas. Their vocal repertoires matched those of two other clans (called Short and Four-Plus) found across the Pacific but previously rare or absent around Galápagos. The mechanisms behind this cultural turnover may include large-scale environmental regime shifts favouring clan-specific foraging strategies, and a response to heavy whaling in the region involving redistribution of surviving whales into high-quality habitats. The fall and rise of sperm whale cultures off Galápagos reflect the structuring of the Pacific population into large, enduring clans with dynamic ranges. Long-lasting clan membership illustrates how culture can be bound up in the structure and dynamics of animal populations and so how tracking cultural traits can reveal large-scale population shifts.

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Dataset results

Data from: Lineage fusion in Galápagos giant tortoises

Data from: Genetic rediscovery of an 'extinct' Galápagos giant tortoise species

Data from: Hybridization masks speciation in the evolutionary history of the Galápagos marine iguana

Data from: Genome-wide assessment of diversity and divergence among extant Galápagos giant tortoise species

Data from: Cultural turnover among Galápagos sperm whales

FIGURES 11­15. Elachiptera eulophus. 11 in A new species of Elachiptera Macquart from the Galápagos Islands, Ecuador, and the taxonomic status of Ceratobarys Coquillett (Diptera: Chloropidae)

FIGURES 6­10. Elachiptera attenuata. 6 in A new species of Elachiptera Macquart from the Galápagos Islands, Ecuador, and the taxonomic status of Ceratobarys Coquillett (Diptera: Chloropidae)

FIGURES 1­5. Elachiptera cultrata. 1 in A new species of Elachiptera Macquart from the Galápagos Islands, Ecuador, and the taxonomic status of Ceratobarys Coquillett (Diptera: Chloropidae)

Figs 173-177 in Taxonomic revision of the Spilomelinae (Lepidoptera, Pyralidae s. l.) of the Galápagos Islands, Ecuador

Figs 168-172 in Taxonomic revision of the Spilomelinae (Lepidoptera, Pyralidae s. l.) of the Galápagos Islands, Ecuador

Figs 178-183 in Taxonomic revision of the Spilomelinae (Lepidoptera, Pyralidae s. l.) of the Galápagos Islands, Ecuador

Figs 163-167 in Taxonomic revision of the Spilomelinae (Lepidoptera, Pyralidae s. l.) of the Galápagos Islands, Ecuador

Figs 158-162 in Taxonomic revision of the Spilomelinae (Lepidoptera, Pyralidae s. l.) of the Galápagos Islands, Ecuador

Figs 153-157 in Taxonomic revision of the Spilomelinae (Lepidoptera, Pyralidae s. l.) of the Galápagos Islands, Ecuador

Figs 148-152 in Taxonomic revision of the Spilomelinae (Lepidoptera, Pyralidae s. l.) of the Galápagos Islands, Ecuador

Figs 136-137 in Taxonomic revision of the Spilomelinae (Lepidoptera, Pyralidae s. l.) of the Galápagos Islands, Ecuador

Figs 143-147 in Taxonomic revision of the Spilomelinae (Lepidoptera, Pyralidae s. l.) of the Galápagos Islands, Ecuador

Figs 138-142 in Taxonomic revision of the Spilomelinae (Lepidoptera, Pyralidae s. l.) of the Galápagos Islands, Ecuador

Figs 125-127 in Taxonomic revision of the Spilomelinae (Lepidoptera, Pyralidae s. l.) of the Galápagos Islands, Ecuador

Figs 128-130 in Taxonomic revision of the Spilomelinae (Lepidoptera, Pyralidae s. l.) of the Galápagos Islands, Ecuador

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FIGURES 1115. Elachiptera eulophus. 11 in A new species of Elachiptera Macquart from the Galápagos Islands, Ecuador, and the taxonomic status of Ceratobarys Coquillett (Diptera: Chloropidae)

FIGURES 610. Elachiptera attenuata. 6 in A new species of Elachiptera Macquart from the Galápagos Islands, Ecuador, and the taxonomic status of Ceratobarys Coquillett (Diptera: Chloropidae)

FIGURES 15. Elachiptera cultrata. 1 in A new species of Elachiptera Macquart from the Galápagos Islands, Ecuador, and the taxonomic status of Ceratobarys Coquillett (Diptera: Chloropidae)