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1.
    
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.  相似文献   

2.
3.
    
The behavior of groups of female and immature sperm whales (Physeter macrocephalus) was measured on 117 d within an 11-yr period off the Galápagos Islands, Ecuador. On each day, up to 18 measures of visually observable behavior were calculated. These concerned speeds, headings, movement patterns, diving synchrony, foraging formations, time spent socializing, and aerial behavior. The measured behavior of the sperm whales was considerably more variable when they were socializing than when foraging. None of the measures showed much correlation with sea-surface temperature, and only measures of consistency of movement were significantly correlated with defecation rate, an indicator of feeding success. However, month-long time periods accounted for over 50% of the variance in eight of eighteen measures, and, in the cases of surface speed and dive synchrony, the effects were statistically significant. In contrast, there was no autocorrelation with lag of one day in the residuals of any of the measures. Thus, behavior may be tracking substantial temporal variation in the whales' environment over scales of about several months. Groups of whales had significantly different travel patterns, but there was little other evidence for group-specific behavior, perhaps because tests of group-specific effects were not of adequate statistical power. Variation in sperm whale behavior, especially over time scales of a few months or longer and spatial scales of a few hundred kilometers or larger, should be considered when estimating densities from sighting surveys.  相似文献   

4.
    
Domesticated animals that revert to a wild state can become invasive and significantly impact native biodiversity. Although dogs can be problematic locally, only the Australasian dingo is known to occur in isolation from humans. Western dogs have experienced more intense artificial selection, which potentially limits their invasiveness. However, feral dogs eradicated from Isabela Island, Galápagos in the 1980s could be the first‐known exception. We used DNA and morphometric data from 92 of these dogs to test the hypotheses that (i) these dogs persisted independently of humans for up to a century and a half since descending from a handful of dogs introduced in the early 1800s, vs. (ii) similarly to other western feral dog populations, they reflected continuous recruitment of strays from human settlements on a portion of the Island. We detected one dominant maternal lineage and one dominant paternal lineage shared by the three subpopulations, along with low autosomal genetic diversity, consistent with the hypothesized common origins from a small founder population. Genetic diversity patterns among the three island subpopulations were consistent with stepping‐stone founder effects, while morphometric differentiation suggested rapid phenotypic divergence, possibly due to drift and reinforced by selection corresponding to distinct microclimates and habitats on Isabela. Despite the continued presence of free‐ranging dogs in the vicinity of settlements on Isabela and other Galápagos Islands, feral populations have not reestablished in remote areas since the 1980s, emphasizing the rarity of conditions necessary for feralization of modern western dogs.  相似文献   

5.
The Opuntia (prickly pear) genus contains over 200 species. Six of them are endemic to the Galapagos archipelago. Although these cacti are ‘keystone’ species of the Galapagos’ semi‐arid ecosystem, they have never been studied in detail. Because of their current threatened status and their important role in the ecosystem, we developed 16 microsatellite markers to study the population genetic structure of some of these species. These markers display a high level of polymorphism with numbers of alleles per locus ranging from six to 53. Results also revealed possible polyploidy in these cacti.  相似文献   

6.
    
Five microsatellite loci were isolated from the Galápagos caterpillar hunter Calosoma granatense. Polymorphism ranges from four to 14 alleles, and observed and expected heterozygosities range from 0.138 to 0.889 and 0.197–0.902, respectively. Cross‐amplification of the developed primers was successful in the related species C. leleuporum.  相似文献   

7.
    
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 ~199 000 years ago. Following arrival of the second wave of colonists, both lineages coexisted for approximately ~53 000 years. 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.  相似文献   

8.
    
Primers were developed for the amplification and sequencing of the mitochondrial control region of Galápagos land (Conolophus) and marine (Amblyrhynchus) iguanas. Sequences were obtained for four land iguana samples from two islands and for 28 marine iguana samples from three islands. A series of 70–80 bp tandem repeats adjacent to the control region are described and preliminary quantification of intra‐ and interspecific sequence divergence is included.  相似文献   

9.
The Galápagos land iguanas (genus Conolophus) have faced significant anthropogenic disturbances since the 17th century, leading to severe reduction of some populations and the extinction of others. Conservation activities, including the repatriation of captive‐bred animals to depleted areas, have been ongoing since the late 1970s, but genetic information has not been extensively incorporated. Here we use nine species‐specific microsatellite loci of 703 land iguanas from the six islands where the species occur today to characterize the genetic diversity within, and the levels of genetic differentiation among, current populations as well as test previous hypotheses about accidental translocations associated with early conservation efforts. Our analyses indicate that (i) five populations of iguanas represent distinct conservation units (one of them being the recently discovered rosada form) and could warrant species status, (ii) some individuals from North Seymour previously assumed to be from the natural Baltra population appear related to both Isabela and Santa Cruz populations, and (iii) the five different management units exhibit considerably different levels of intrapopulation genetic diversity, with the Plaza Sur and Santa Fe populations particularly low. Although the initial captive breeding programmes, coupled with intensive efforts to eradicate introduced species, saved several land iguana populations from extinction, our molecular results provide objective data for improving continuing in situ species survival plans and population management for this spectacular and emblematic reptile.  相似文献   

10.
    
We sampled mosquitoes across 18 sites established at different elevations and stretching from the north to the south of Isla Santa Cruz, Galápagos. Two commonly occurring species, Ae. taeniorhynchus and Cx. quinquefasciatus, were collected along with environmental variables characteristic of the trapping sites to assess their influence on mosquito abundance and occurrence in the dry season of 2015. We captured Ae. taeniorhynchus at 14 out of 18 sites and Cx. quinquefasciatus at low and high elevation sites on Santa Cruz. We utilized two generalized linear models; the first assessed the influence of environmental variables on abundances of Ae. taeniorhynchus and the second assessed the influence of these variables on the presence of Cx. quinquefasciatus. Populations of both mosquito species declined with elevation. Rainfall data were limited, as we sampled during the dry season of 2015. Distance to mangroves and maximum humidity were significant in influencing the abundance of Ae. taeniorhynchus, while maximum humidity was found to significantly influence the presence of Cx. quinquefasciatus. Both species occurred in sites where temperature, precipitation, and humidity should allow for mosquito development as well as parasitic development of the protozoan parasites that cause avian malaria. Further research involving year‐round sampling of mosquitoes and accompanying meteorological data as well as experimental studies on vector competence are required to understand disease dynamics of parasites such as avian malaria in Galápagos.  相似文献   

11.
    
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.  相似文献   

12.
    
Summary

Vicariance and dispersion both must be considered as possibilities for the fauna and flora of New Zealand and New Caledonia. Oligocene submersion, promoted by the geologists and several biologists, does not seem to have been total. Refuge stations must have existed in mountains and even in plains in some surrounding areas. From there the relicts must have radiated after the partial submersion. Certain “primitive” Chrysomelidae Eumolpinae (Bohumiljania spp.) are closely related to Patagonian genera. Their case is not unique among the terrestrial organisms of New Caledonia. How to explain the occurrence of Amborella in New Caledonia and of the tuataras in New Zealand, already very probably extinct elsewhere during the Paleogene?  相似文献   

13.
    
Long‐term population history can influence the genetic effects of recent bottlenecks. Therefore, for threatened or endangered species, an understanding of the past is relevant when formulating conservation strategies. Levels of variation at neutral markers have been useful for estimating local effective population sizes (Ne) and inferring whether population sizes increased or decreased over time. Furthermore, analyses of genotypic, allelic frequency, and phylogenetic information can potentially be used to separate historical from recent demographic changes. For 15 populations of Galápagos giant tortoises (Chelonoidis sp.), we used 12 microsatellite loci and DNA sequences from the mitochondrial control region and a nuclear intron, to reconstruct demographic history on shallow (past ~100 generations, ~2500 years) and deep (pre‐Holocene, >10 thousand years ago) timescales. At the deep timescale, three populations showed strong signals of growth, but with different magnitudes and timing, indicating different underlying causes. Furthermore, estimated historical Ne of populations across the archipelago showed no correlation with island age or size, underscoring the complexity of predicting demographic history a priori. At the shallow timescale, all populations carried some signature of a genetic bottleneck, and for 12 populations, point estimates of contemporary Ne were very small (i.e., < 50). On the basis of the comparison of these genetic estimates with published census size data, Ne generally represented ~0.16 of the census size. However, the variance in this ratio across populations was considerable. Overall, our data suggest that idiosyncratic and geographically localized forces shaped the demographic history of tortoise populations. Furthermore, from a conservation perspective, the separation of demographic events occurring on shallow versus deep timescales permits the identification of naturally rare versus newly rare populations; this distinction should facilitate prioritization of management action.  相似文献   

14.
Aim  To describe New Zealand's historical terrestrial biogeography and place this history in a wider Southern Hemisphere context.
Location  New Zealand.
Methods  The analysis is based primarily on literature on the distributions and relationships of New Zealand's terrestrial flora and fauna.
Results  New Zealand is shown to have a biota that has broad relationships, primarily around the cool Southern Hemisphere, as well as with New Caledonia to the north. There are hints of ancient Gondwanan taxa, although the long-argued predominance of taxa derived by vicariant processes, driven by plate tectonics and the fragmentation of Gondwana, is no longer accepted as a principal explanation of the biota's origins and relationships.
Main conclusions  Most of the terrestrial New Zealand flora and fauna has clearly arrived in New Zealand much more recently than the postulated separation of New Zealand from Gondwana, dated at c. 80 Ma. There is a view that New Zealand may have disappeared completely beneath the sea in the early Cenozoic, and acceptance of this would mean derivation of the entire biota by transoceanic dispersal. However, there are elements in the biota that seem to have broad distributions that date back to Gondwanan times, and also some that are thought unlikely to have been able to disperse to New Zealand across ocean gaps, especially freshwater organisms. Very strong connections to the biota of Australia, rather than to South America, are inconsistent with the timing of New Zealand's ancient and early separation from Gondwana and seem likely to have resulted from dispersal.  相似文献   

15.
    
Efforts to eradicate nonnative mammals to restore oceanic island ecosystems have become increasingly successful but parallel tracking of response by native species for which control efforts are intended to benefit has been rare. A major campaign to eradicate nonnative goats and burros was initiated in 1995 on Alcedo Volcano in the Galápagos Archipelago that ultimately removed 62,868 goats and eliminated them by 2006. Planners of the eradication program had the foresight to invest in intensive monitoring of the status of the volcano's giant tortoise (Chelonoidis nigra) population whose welfare was a primary motivation for the eradication effort. Monitoring revealed an increase in the proportion of juveniles among all tortoises as well as increased growth rates of individual tortoises on Alcedo Volcano from earlier to later phases of the eradication campaign. Over the same time frame in a control population on nearby Santa Cruz Island (where goats and donkeys were not removed) juvenile fraction and individual growth rates remained unchanged. Although goat removal coincided with occurrence of a rare climatic event that simultaneously boosted forage availability for tortoises, failure to observe a comparable improvement in the control population implies that removal of goats and burros was the primary causative factor of improving population status of tortoises on Alcedo Volcano.  相似文献   

16.
    
Abrotanella is the basal genus in the large tribe Senecioneae (Asteraceae) and has a disjunct distribution in Australasia and South America. A recent molecular phylogeny of the genus was used to investigate whether the main biogeographical patterns in the group could be related to the region's tectonic history in a coherent way. The phylogenetic/biogeographical breaks and overlaps in the genus imply a series of vicariance and range expansion events. Each of these can be related to one of the main tectonic events in the region, including assembly of the New Zealand terranes, crustal extension, and magmatism in Gondwana that preceded seafloor spreading, opening of the Tasman and Pacific basins, and transcurrent movement on the New Zealand Alpine fault. The coincident sequence indicates that pre‐drift tectonics and magmatism have been more important for the origin of trans‐Tasman and trans‐Pacific groups than the final rifting of Gondwana that led to their disjunction. For example, during the pre‐drift phase of break‐up, the Whitsunday volcanic province of Australia and the Median Batholith of New Zealand formed a large, active igneous belt. Its distribution is aligned with the break between New Zealand–south‐eastern Australia clades, and New Zealand–New Guinea clades. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, ??, ??–??.  相似文献   

17.
    
Beak shape in Darwin's ground finches (Geospiza) is emblematic of natural selection and adaptive radiation, yet our understanding of the genetic basis of beak shape variation, and thus the genetic target of natural selection, is still evolving. Here we reveal the genomic architecture of beak shape variation using genomewide comparisons of four closely related and hybridizing species across 13 islands subject to parallel natural selection. Pairwise contrasts among species were used to identify a large number of genomic loci that are consistently related to species differences across a complex landscape. These loci are associated with hundreds of genes that have enriched GO categories significantly associated with development. One genomic region of particular interest is a section of Chromosome 1A with many candidate genes and increased linkage. The distinct, pointed beak shape of the cactus finch is linked to an excess of intermediate frequency alleles and increased heterozygosity in significant SNPs, but not across the rest of the genome. Alleles associated with pointier beaks among species were associated with pointier‐beaked populations within each species, thus establishing a common basis for natural selection, species divergence and adaptive radiation. The adaptive genomic landscape for Darwin's finches mirrors theoretical expectations based on morphological variation. The implication that a large number of genes are actively maintained to facilitate beak variation across parallel populations with documented interspecies admixture challenges our understanding of evolutionary processes in the wild.  相似文献   

18.
    
Culex quinquefasciatus Say (Diptera: Culicidae), an important vector of West Nile virus (WNV) in the U.S.A., was first detected on the Galápagos Islands (Ecuador) in the 1980s. However, little is known of its ecology, distribution or capacity for arbovirus transmission in the Galápagos. We characterize details of lifecycle (including gonotrophic period), temporal abundance, spatial distribution, vector competence and host‐feeding behaviour. Culex quinquefasciatus was detected on five islands of the Galápagos during 2006–2011. A period of 7–14 days was required for egg–adult emergence; water salinity above 5 ppt was demonstrated to hinder larval development. Blood‐meal analysis indicated feeding on reptiles, birds and mammals. Assessment of WNV vector competency of Galápagos C. quinquefasciatus showed a median infectious dose of 7.41 log10 plaque‐forming units per millilitre and evidence of vertical transmission (minimal filial infection rate of 3.7 per 1000 progeny). The distribution of C. quinquefasciatus across the archipelago could be limited by salt intolerance, and its abundance constrained by high temperatures. Feeding behaviour indicates potential to act as a bridge vector for transmission of pathogens across multiple taxa. Vertical transmission is a potential persistence mechanism for WNV on Galápagos. Together, our results can be used for epidemiological assessments of WNV and target vector control, should this pathogen reach the Galápagos Islands.  相似文献   

19.
    
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.  相似文献   

20.
We describe here the cloning of 12 (7 dinucleotide, 1 trinucleotide and 4 tetranucleotide) microsatellite loci for the Galápagos marine iguana Amblyrhynchus cristatus. When tested for individuals from five different island populations on the Galápagos archipelago, high genetic diversities (9–20 alleles per locus) and heterozygosities (0.200–0.944) were observed. All loci showed no obvious deviations from Hardy–Weinberg equilibrium. The new set of microsatellite loci was able to assign individuals reliably to their island of origin, thus being able to discriminate between residents and migrants between islands.  相似文献   

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