Froyd C.A.,University of Swansea |
Froyd C.A.,University of Oxford |
Coffey E.E.D.,University of Oxford |
van der Knaap W.O.,University of Bern |
And 4 more authors.
Ecology Letters | Year: 2014
The giant tortoises of the Galápagos have become greatly depleted since European discovery of the islands in the 16th Century, with populations declining from an estimated 250 000 to between 8000 and 14 000 in the 1970s. Successful tortoise conservation efforts have focused on species recovery, but ecosystem conservation and restoration requires a better understanding of the wider ecological consequences of this drastic reduction in the archipelago's only large native herbivore. We report the first evidence from palaeoecological records of coprophilous fungal spores of the formerly more extensive geographical range of giant tortoises in the highlands of Santa Cruz Island. Upland tortoise populations on Santa Cruz declined 500-700 years ago, likely the result of human impact or possible climatic change. Former freshwater wetlands, a now limited habitat-type, were found to have converted to Sphagnum bogs concomitant with tortoise loss, subsequently leading to the decline of several now-rare or extinct plant species. © 2013 John Wiley & Sons Ltd/CNRS.
Cruz-Delgado F.,National Park Service |
Gonzalez J.A.,Autonomous University of Madrid |
Wiedenfeld D.A.,Charles Darwin Research Station
Bird Conservation International | Year: 2010
The Galapagos Petrel Pterodroma phaeopygia is endemic to the Galapagos Archipelago, where it nests on only five islands. The species is considered 'Critically Endangered', mostly due to the effects of alien invasive species, which impair its reproductive success. During 2002-2003 we studied the breeding biology of the petrels nesting on San Cristóbal island. The study revealed particular characteristics of the San Cristóbal petrel population and differences compared to those of other islands, mostly related to nesting habitat, phenology, reproductive success and causes of mortality. On San Cristóbal, petrel nests were primarily located along ravines, in areas of dense vegetation cover formed by the endemic shrub Miconia robinsoniana and a wide variety of native ferns. Over 90% of the nests on the island were located on private agricultural land. The petrel population has a prolonged reproductive period covering 10 months. Laying dates occurred mostly from May to October, with a peak during August, although eggs may be occasionally laid between November and March. The incubation period averaged 50.8 days (range: 46-53), and parental care 103.7 days (range: 98-108). Overall reproductive success was 23.6%; 63.8% for eggs and 37.1% for chicks. Predation by rats was the primary cause (72.2%) of nest failure. Rat control campaigns and clearing of exotic plant species in areas of high density of petrel nests, as well as promoting cooperation agreements between conservation authorities and landowners of the properties where nests are located, are suggested among other critical management measures intended to reduce nest mortality and ensure the survival of the San Cristóbal petrel population. Copyright © BirdLife International 2010.
Meise K.,Bielefeld University |
Garcia-Parra C.,Charles Darwin Research Station
Marine Biology | Year: 2015
Parasitic infections can play a major role in the dynamics of animal populations by influencing the development and survival of juveniles. Understanding how intrinsic and extrinsic factors shape individual parasitisation and affect long-term consequences of infections is therefore of prime importance for conservation management. Galapagos sea lions (Zalophus wollebaeki) provide a good model system to assess the impact of environmental and behavioural differences on parasitisation. Their environment is characterised by seasonal changes in sea surface temperatures (SST), and the slow transition to independence in juveniles goes along with major behavioural changes. The present study focused on infections with Philophthalmus zalophi, a digenetic trematode, which is regularly found in the ocular cavity of young sea lions. Long-term data on P. zalophi infections were collected from a sea lion colony located in the centre of the Galapagos archipelago (0°45′S, 90°160′W, 2007–2014). The probability to become infected differed between age classes and was influenced by the SST at the time of capture. About 16 % of the animals infected during the peak of infections developed severe clinical signs which had long-term consequences for juvenile survival. The transition to independence appeared to be a particularly sensitive period when negative consequences of previous parasitic infections exerted the greatest influence on juvenile survival. Our results suggest that the prevalence of infections and thus the negative implications for juvenile survival may increase with broad-scale climatic changes. © 2015, Springer-Verlag Berlin Heidelberg.
Phillips R.B.,Charles Darwin Research Station |
Phillips R.B.,University of New Mexico |
Wiedenfeld D.A.,Charles Darwin Research Station |
Snell H.L.,Charles Darwin Research Station |
Snell H.L.,University of New Mexico
Biological Invasions | Year: 2012
Human activity has promoted the invasion of the Galápagos Islands by alien species from each of the five classes of vertebrates. We review the current distribution of alien vertebrates in the archipelago, their impacts on native species, and management efforts aimed at alien vertebrates. A total of 44 species have been reported in the archipelago, with 20 species establishing feral populations. Mammals were the first group arriving in the archipelago and remain the most numerous, with 10 established species. Alien birds invaded after mammals and four species have established populations. Reptiles, amphibians, and fish invaded later and are represented by three, one, and two species, respectively. Alien mammals are the most injurious to native biota, contributing to the decline or extinction of several species. Aside from mammals, no other class of alien vertebrate has had documented impacts on native species. Several populations of large and medium-sized mammals and birds have been eradicated. © 2011 Springer Science+Business Media B.V.
Bungartz F.,Charles Darwin Research Station |
Bungartz F.,Charles Darwin Foundation |
Lucking R.,The Field Museum |
Aptroot A.,ABL Herbarium
Nova Hedwigia | Year: 2010
As part of an ongoing comprehensive inventory of the Galapagos lichen flora, all species in the Graphidaceae from the archipelago have been revised using both historic and recent collections. A total of forty-two species is reported here, of which thirty-four were previously unknown from the archipelago and two are described as new to science: Graphis pedunculata, and Phaeographis striata. The new combinations Carbacanthographis saxiseda, Carbacanthographis saxorum and Phaeographis major are made. Four previously reported species are based on misidentifications and thus removed from the checklist. Detailed descriptions are presented that include diagnostic characteristics to distinguish similar species. An identification key to all Galapagos Graphidaceae is provided and a preliminary assessment discusses known distribution and ecology for each of the species. Principal components analysis was used to assess ecology for thirty-nine species. © 2010 J. Cramer in der Gebrüder Borntraeger Verlagsbuchhandlung.
Brumm H.,Max Planck Institute for Ornithology (Seewiesen) |
Farrington H.,University of Cincinnati |
Petren K.,University of Cincinnati |
Fessl B.,Charles Darwin Research Station |
Fessl B.,California State University, Channel Islands
PLoS ONE | Year: 2010
Understanding the mechanisms underlying speciation remains a challenge in evolutionary biology. The adaptive radiation of Darwin's finches is a prime example of species formation, and their study has revealed many important insights into evolutionary processes. Here, we report striking differences in mating signals (songs), morphology and genetics between the two remnant populations of Darwin's mangrove finch Camarhynchus heliobates, one of the rarest species in the world. We also show that territorial males exhibited strong discrimination of sexual signals by locality: in response to foreign songs, males responded weaker than to songs from their own population. Female responses were infrequent and weak but gave approximately similar results. Our findings not only suggest speciation in the mangrove finch, thereby providing strong support for the central role of sexual signals during speciation, but they have also implications for the conservation of this iconic bird. If speciation is complete, the eastern species will face imminent extinction, because it has a population size of only 5-10 individuals. © 2010 Brumm et al.
Gibbs J.P.,New York University |
Sterling E.J.,CNRS Center for Marine Biodiversity, Exploitation and Conservation |
Zabala F.J.,Charles Darwin Research Station
Biotropica | Year: 2010
Giant tortoises were once a megafaunal element widespread in tropical and subtropical ecosystems. The role of giant tortoises as herbivores and seed dispersers, however, is poorly known. We evaluated tortoise impacts on Opuntia cactus (Cactaceae) in the Galápagos Islands, one of the last areas where giant tortoises remain extant, where the cactus is a keystone resource for many animals. We contrasted cactus populations immediately inside and outside natural habitats where tortoises had been held captive for several decades. Through browsing primarily and trampling secondarily tortoises strongly reduced densities of small (0.5-1.5 m high) cacti, especially near adult cacti, and thereby reduced densities of cacti in larger size classes. Tortoises also caused a shift from vegetative to sexual modes of reproduction in cacti. We conclude that giant tortoises promote a sparse and scattered distribution in Opuntia cactus and its associated biota in the Galápagos Islands. 2009 The Author(s). Journal compilation © 2009 by The Association for Tropical Biology and Conservation.
Landry B.,Museum dHistoire Naturelle |
Roque-Albelo L.,Charles Darwin Research Station
Revue Suisse de Zoologie | Year: 2010
The Gelechiidae of the Galapagos Islands are revised. Twenty-two species are recognized to be established on the archipelago, including eight described as new: Ephysteris sporobolella Landry (bred from Sporobolus virginicus (L.) Kunth (Poaceae)), E. scimitarella Landry, Scrobipalpula inornata Landry, S. equatoriella Landry, S. caustonae Landry, Stegasta francisci Landry, Symmetrischema escondidella Landry, and Untomia lunatella Landry. Agnippe omphalopa (Meyrick, 1917), comb, n., Anacampsis primigenia Meyrick, 1918, Aristotelia sarcodes Walsingham, 1910, Compsolechia salebrosa Meyrick, 1918, Dicho meris acuminatus (Staudinger, 1876), Ephysteris subdiminutella (Stainton, 1867), Mesophleps adustipennis (Walsingham, 1897) comb, n., Phthorimaea perfidiosa Meyrick, 1917, Scrobipalpula densata (Meyrick, 1917), and Stegasta zygotoma Meyrick, 1917 are reported from the archipelago for the first time. Four additional species had been reported from the archipelago before. A lectotype is designated for Echinoglossa trinota Clarke, 1965 from Masatierra, Juan Fernandez Islands. New host plant records are provided for A. omphalopa, A. primigenia, C. salebrosa, M. adustipennis, and P. absoluta.
Guerrero A.M.,Charles Darwin Research Station |
Tye A.,Charles Darwin Research Station
Ornitologia Neotropical | Year: 2011
We investigated seed dispersal by seven Galapagos land-bird species, six of them native or endemic (Galapagos Dove Zenaida galapagoensis. Dark-billed Cuckoo Coccyzus melacoryphus, Vermilion Flycatcher Pyrocephalus rubinus nanus, Galapagos Flycatcher Myiarchus magnirostns, Galapagos Mockingbird Nesomimus parvulus, and Yellow Warbler Dendroica petechia aureola), plus the introduced Smooth-billed Ani Crotophaga ani. Most of these were previously regarded primarily as seed predators or insectivores. All were found to eat fruit except the Vermilion Flycatcher, which appears to be exclusively insectivorous. The Galapagos Flycatcher, Galapagos Mockingbird, and Yellow Warbler defaecated viable seeds, while the flycatcher and mockingbird also regurgitated viable seeds. A large proportion of the feces of these three species contained viable seeds; they are therefore common dispersers, potentially over long distances. Most Smooth-billed Ani stomachs also contained viable seeds. The most frequently encountered intact seeds in feces were of the fleshy-fruited shrubs Tournefortia spp., Miconia robinsoniana, Scutia spicata, and the introduced invasive blackberry Rubus niveus. Spread of plants by these birds is probably more common than previously assumed from their predominant feeding patterns of seed predation and insectivory. Land birds in Galapagos probably play an important role in Galapagos plant population and vegetation community dynamics, via intra- and inter-island dispersal of ingested seeds. The invasive ani may be changing the dispersal dynamics of native plants as well as increasing the spread of the invasive Rubus niveus. © The Neotropical Ornithological Society.
Tye A.,Charles Darwin Research Station
Novon | Year: 2010
Following molecular phylogenetic evidence that the Galápagos (Ecuador) endemic genus Darwiniothamnus Harling (Asteraceae, Astereae) is biphyletic, with supporting evidence from several morphological traits, the species D. alternifolius is transferred to the genus Erigeron L. as E. alternifolius (Lawesson & Adsersen) N. Andrus & Tye. © Missouri Botanical Garden 2010.