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.     

Population Response of Giant Galápagos Tortoises to Feral Goat Removal

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.     

Population genetics of Galápagos land iguana (genus Conolophus) remnant populations

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.     

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.     

Urban living influences the nesting success of Darwin’s finches in the Galápagos Islands

Urbanization is expanding worldwide with major consequences for organisms. Anthropogenic factors can reduce the fitness of animals but may have benefits, such as consistent human food availability. Understanding anthropogenic trade‐offs is critical in environments with variable levels of natural food availability, such as the Galápagos Islands, an area of rapid urbanization. For example, during dry years, the reproductive success of bird species, such as Darwin''s finches, is low because reduced precipitation impacts food availability. Urban areas provide supplemental human food to finches, which could improve their reproductive success during years with low natural food availability. However, urban finches might face trade‐offs, such as the incorporation of anthropogenic debris (e.g., string, plastic) into their nests, which may increase mortality. In our study, we determined the effect of urbanization on the nesting success of small ground finches (Geospiza fuliginosa; a species of Darwin''s finch) during a dry year on San Cristóbal Island. We quantified nest building, egg laying and hatching, and fledging in an urban and nonurban area and characterized the anthropogenic debris in nests. We also documented mortalities including nest trash‐related deaths and whether anthropogenic materials directly led to entanglement‐ or ingestion‐related nest mortalities. Overall, urban finches built more nests, laid more eggs, and produced more fledglings than nonurban finches. However, every nest in the urban area contained anthropogenic material, which resulted in 18% nestling mortality while nonurban nests had no anthropogenic debris. Our study showed that urban living has trade‐offs: urban birds have overall higher nesting success during a dry year than nonurban birds, but urban birds can suffer mortality from anthropogenic‐related nest‐materials. These results suggest that despite potential costs, finches benefit overall from urban living and urbanization may buffer the effects of limited resource availability in the Galápagos Islands.     

Host‐specific associations affect the microbiome of Philornis downsi,an introduced parasite to the Galápagos Islands

The composition and diversity of bacteria forming the microbiome of parasitic organisms have implications for differential host pathogenicity and host–parasite co‐evolutionary interactions. The microbiome of pathogens can therefore have consequences that are relevant for managing disease prevalence and impact on affected hosts. Here, we investigate the microbiome of an invasive parasitic fly Philornis downsi, recently introduced to the Galápagos Islands, where it poses extinction threat to Darwin's finches and other land birds. Larvae infest nests of Darwin's finches and consume blood and tissue of developing nestlings, and have severe mortality impacts. Using 16s rRNA sequencing data, we characterize the bacterial microbiota associated with P. downsi adults and larvae sourced from four finch host species, inhabiting two islands and representing two ecologically distinct groups. We show that larval and adult microbiomes are dominated by the phyla Proteobacteria and Firmicutes, which significantly differ between life stages in their distributions. Additionally, bacterial community structure significantly differed between larvae retrieved from strictly insectivorous warbler finches (Certhidea olivacea) and those parasitizing hosts with broader dietary preferences (ground and tree finches, Geospiza and Camarhynchus spp., respectively). Finally, we found no spatial effects on the larval microbiome, as larvae feeding on the same host (ground finches) harboured similar microbiomes across islands. Our results suggest that the microbiome of P. downsi changes during its development, according to dietary composition or nutritional needs, and is significantly affected by host‐related factors during the larval stage. Unravelling the ecological significance of bacteria for this parasite will contribute to the development of novel, effective control strategies.     

The influence of ecological factors on mosquito abundance and occurrence in Galápagos

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.     

Cryptic diversity in Black rats Rattus rattus of the Galápagos Islands,Ecuador

Human activity has facilitated the introduction of a number of alien mammal species to the Galápagos Archipelago. Understanding the phylogeographic history and population genetics of invasive species on the Archipelago is an important step in predicting future spread and designing effective management strategies. In this study, we describe the invasion pathway of Rattus rattus across the Galápagos using microsatellite data, coupled with historical knowledge. Microsatellite genotypes were generated for 581 R. rattus sampled from 15 islands in the archipelago. The genetic data suggest that there are at least three genetic lineages of R. rattus present on the Galápagos Islands. The spatial distributions of these lineages correspond to the main centers of human settlement in the archipelago. There was limited admixture among these three lineages, and these finding coupled with low rates of gene flow among island populations suggests that interisland movement of R. rattus is rare. The low migration among islands recorded for the species will have a positive impact on future eradication efforts.     

Growth and Reproduction in Forest Trees of the Cactus Opuntia excelsa1

In southwestern México, the number of new cladodes on Opuntia excelsa was a skewed bell-shaped function of size (“size” being the number of cladodes persisting from previous years). Fruit number was a sigmoidal function of size, but the number of seeds per fruit was independent of number of fruits per plant. The curves for production of new cladodes and of fruits both showed maximum increase for plants with 150–350 cladodes, when the crowns were reaching or in the canopy. New cladode production declined at about the size where reproduction plateaued; we suggest this was due to limitation of crown dimensions by mechanical and physiological factors.     

The vector ecology of introduced Culex quinquefasciatus populations,and implications for future risk of West Nile virus emergence in the Galápagos archipelago

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.     

Distribution and Flowering Ecology of Bromeliads along Two Climatically Contrasting Elevational Transects in the Bolivian Andes1

We compared the diversity, taxonomic composition, and pollination syndromes of bromeliad assemblages and the diversity and abundance of hummingbirds along two climatically contrasting elevational gradients in Bolivia. Elevational patterns of bromeliad species richness differed noticeably between transects. Along the continuously wet Carrasco transect, species richness peaked at mid‐elevations, whereas at Masicurí most species were found in the hot, semiarid lowlands. Bromeliad assemblages were dominated by large epiphytic tank bromeliads at Carrasco and by small epiphytic, atmospheric tillandsias at Masicurí. In contrast to the epiphytic taxa, terrestrial bromeliads showed similar distributions across both transects. At Carrasco, hummingbird‐pollination was the most common pollination mode, whereas at Masicurí most species were entomophilous. The proportion of ornithophilous species increased with elevation on both transects, whereas entomophily showed the opposite pattern. At Carrasco, the percentage of ornithophilous bromeliad species was significantly correlated with hummingbird abundance but not with hummingbird species richness. Bat‐pollination was linked to humid, tropical conditions in accordance with the high species richness of bats in tropical lowlands. At Carrasco, mixed hummingbird/bat‐pollination was found especially at mid‐elevations, i.e., on the transition between preferential bat‐pollination in the lowlands and preferential hummingbird‐pollination in the highlands. In conclusion, both richness patterns and pollination syndromes of bromeliad assemblages varied in distinct and readily interpretable ways in relation to environmental humidity and temperature, and bromeliad pollination syndromes appear to follow the elevational gradients exhibited by their pollinators.     

在韩国境内Potentilla fragarioides var .sprengeliana的遗传多样性和种群结构(英文)

根据 2 2个等位酶位点遗传变异 ,探讨了韩国境内委陵菜 (PotentillafragarioidesL .var.sprengeliana)的遗传多样性和种群结构。酶位点的多态位点百分比为 5 9 1%。种和种群水平上的遗传多样性比较高 ,分别为Hes=0 .2 10 ,Hep=0 .199;而种群的分化水平则相对较低 (GST=0 .0 74)。 19个种群中随机交配的偏差为FIS=0 .331。每代迁移数的间接估计 (Nm=3.15 )表明该种在韩国的种群间基因流较高。另外 ,固定指数分析显示在一些种群和位点有轻微的杂合子缺乏。种群间平均遗传一致度为 0 985。这些韩国委陵菜种群存在于较为均一的生境 ,这很有可能是造成其种群遗传一致性较高的原因。     

Patterns of Genetic Diversity and Population Structure of the Clonal Herb,Potentilla fragarioides var. sprengeliana (Rosaceae) in Korea

The genetic diversity and population structure of Potentilla fragarioides var. sprengeliana(Rosaceae) in Korea were investigated using genetic variation at 22 allozyme loci. The percent of polymorphic loci within the enzymes was 59.1%. The genetic diversity at the species level and at the population level was high (Hes=0.210; Hep=0.199, respectively), whereas the extent of the population divergence was relatively low (GST=0.074). FIS, a measure of the deviation from random mating within the 19 populations, was 0.331. An indirect estimate of the number of migrants per generation (Nm=3.15) indicates that gene flow is high among Korean populations of the species. In addition, analysis of fixation indices revealed a slight heterozygote deficiency in some populations and at some loci. The mean genetic identity between populations was 0.985. It is highly probable that the trend of genetic uniformity in a relatively homogeneous habitat is thought to be operated among Korean populations of P. fragarioides var.sprengeliana.     

西双版纳片断热带雨林30多年来植物种类组成及种群结构的变化

通过对西双版纳景洪曼仰广的“龙山”片断热带雨雨林30年前后植物区系组成和样方调查资料的对比研究,探讨了30年来该“龙山”片断热带雨林植物区系组成、生活型及群落生态成分和乔木树种的种群变化规律。在植物区系组成上,已确认有种子植物7科53属55种从该片断雨林中消失。在消失的这55种植物中,属于群落顶级成分的有18种,属于耐阴的林下和层间植物有30种,喜阳种类有2种,广生态幅的随遇种有5种。初步得出该龙山热带雨林随着30多年的片断化,8．8％的科,26．8％的属和22．4％的种类消失或被后来的成分替换了。在生活型及群落生态成分变化上,群落中小高位芽及一年生植物相对增加,阳性植物明显增加,阴生（耐阴）植物明显减少,亦即雨林固有成分减少,非雨林成分增加。在乔木树种的种群变化上,过去该片断雨林的优势成份,绝大多数现在仍存在,多数仍在优势种之列,少数优势种衰退了,少数变得更优势。首先消失的种类,或为先锋树种（短命）或为种群数量很少的树种。     

Regional‐Scale Variation in Litter Production and Seasonality in Tropical Dry Forests of Southern Mexico1

Highly seasonal rainfall creates a pulse of litterfall in the southern Yucatan peninsula region, with cascading effects on the timing of essential nutrient fluxes, microbial dynamics, and vegetation growth. I investigated whether forest age or a regional environmental gradient related to rainfall has a greater effect on patterns of litterfall in this increasingly human‐dominated landscape. Litterfall was sampled in 10–13 stands in each of three locations spanning a rainfall gradient of ca 900–1400 mm/yr. Litter was collected monthly from November 1998 through January 2000 in mature forests and in secondary forests aged 2–25 yr. Despite a substantial precipitation gradient, age was the only significant predictor of annual litter mass. Two‐ to five‐yr‐old forests produced significantly less litter than 12–25‐yr‐old secondary forests (4.6 vs. 6.2 Mg/ha/yr), but the difference between older secondary forests and mature forests (9 percent) was not significant. Litter production increased with rainfall, but not significantly so. The pattern of litterfall was similar across locations and age classes, with a peak during late March or early April. However, litterfall seasonality was most pronounced in the old secondary and mature forests. Litterfall was more evenly distributed throughout the year in forests under 10 yr old. Seasonality of litterfall was also less pronounced at the wettest site, with less disparity between peak litterfall and off‐peak months. Seasonality was not related to soil texture. Forest age and rainfall are important drivers of litterfall dynamics; however, both litter mass and degree of seasonality depended more strongly on forest age. Thus, the impact of land‐use change on litter nutrient cycling is as great, if not greater, than the constraint imposed by the major natural environmental factor affecting tropical dry forests.     

Reproductive Biology of an Amphicarpic Annual, Polygonum thunbergii (Polygonaceae): Spatio-temporal Changes in Growth, Structure and Reproductive Components of a Population over an Environmental Gradient

Abstract The process and mechanisms of spatio-temporal changes in growth, population structure, as well as various yield and reproductive components of a population of an amphicarpic annual, Polygonum thunbergii (Polygonaceae), with two reproductive systems (aerial chasmogamous flowers and subterranean cleistogamous flowers) along an environmental gradient (light, moisture and soil nitrogen levels) were investigated in the field.
The results clearly demonstrate that growth and allocation patterns, population structure, and reproductive output of individuals changed sharply along the environmental gradient in response to seasonal and spatial changes in resource availability. Models predicted that light conditions bring about one-sided competition, whereas nutrient conditions in the soil engender two-sided competition. As expected, the degree of one-sided competition was prominent in the case of a planophile, Polygonum thunbergii. Allocation patterns, seed outputs, individual seed size as well as relative energy costs of chasmogamous and cleistogamous seed as affected by light and nutrient levels were also critically analyzed. The most noteworthy finding was that the size of chasmogamous seeds sharply decreased in response to a decrease in the light regime, while cleistogamous seed size remained constant along the gradient. However, relative cost of both chasmogamous and cleistogamous seeds sharply increased with decrease in the light level, reflecting different degrees of environmental stress, biotic interference, or both.     

Broad Concordance in the Spatial Distribution of Adaptive and Neutral Genetic Variation across an Elevational Gradient in Deer Mice

When species are continuously distributed across environmental gradients, the relative strength of selection and gene flow shape spatial patterns of genetic variation, potentially leading to variable levels of differentiation across loci. Determining whether adaptive genetic variation tends to be structured differently than neutral variation along environmental gradients is an open and important question in evolutionary genetics. We performed exome-wide population genomic analysis on deer mice sampled along an elevational gradient of nearly 4,000 m of vertical relief. Using a combination of selection scans, genotype−environment associations, and geographic cline analyses, we found that a large proportion of the exome has experienced a history of altitude-related selection. Elevational clines for nearly 30% of these putatively adaptive loci were shifted significantly up- or downslope of clines for loci that did not bear similar signatures of selection. Many of these selection targets can be plausibly linked to known phenotypic differences between highland and lowland deer mice, although the vast majority of these candidates have not been reported in other studies of highland taxa. Together, these results suggest new hypotheses about the genetic basis of physiological adaptation to high altitude, and the spatial distribution of adaptive genetic variation along environmental gradients.     

樟翠尺蛾种群动态与植物群落结构及气候因子的关系

在昆虫种群的研究中,Ｇｉｅｉｒ和Ｃｌａｒｋ等曾经提出生命系统的基本概念[1,2],认为生命系统由一个对象种群和作用于这个种群的环境所组成。控制昆虫种群增长的有密度制约因子(如食源)和非密度制约因子(如气候环境)。昆虫和植物之间的关系,历来是生态学研究的重要领域。通过长期的定点监测,研究某种昆虫种群动态与各种生态因子之间的关系,不仅可揭示动物和植物及环境之间互相影响的关系,对保护生物学理论的某些方面将有所发展,而且可为林业生产和环保工作提供如何应用生态学原理控制虫害,保护生物多样性和维护生态平衡的理论依据。樟翠尺…