Human activity can influence the gut microbiota of Darwin's finches in the Galapagos Islands

The gut microbiota of animal hosts can be influenced by environmental factors, such as unnatural food items that are introduced by humans. Over the past 30 years, human presence has grown exponentially in the Galapagos Islands, which are home to endemic Darwin's finches. Consequently, humans have changed the environment and diet of Darwin's finches, which in turn, could affect their gut microbiota. In this study, we compared the gut microbiota of two species of Darwin's finches, small ground finches (Geospiza fuliginosa) and medium ground finches (Geospiza fortis), across sites with and without human presence, where finches prefer human‐processed and natural food, respectively. We predicted that: (a) finch microbiota would differ between sites with and without humans due to differences in diet, and (b) gut microbiota of each finch species would be most similar where finches have the highest niche overlap (areas with humans) compared to the lowest niche overlap (areas without humans). We found that gut bacterial community structure differed across sites and host species. Gut bacterial diversity was most distinct between the two species at the site with human presence compared to the site without human presence, which contradicted our predictions. Within host species, medium ground finches had lower bacterial diversity at the site with human presence compared to the site without human presence and bacterial diversity of small ground finches did not differ between sites. Our results show that the gut microbiota of Darwin's finches is affected differently across sites with varying human presence.     

Denitrification in Bahia Darwin (Galapagos Islands) an intermittent anoxic basin in the tropics

Changes in oxygen and nitrate in Bahia Darwin between July 1968 and March 1969 indicate that denitrification occurred in the deeper waters of this tropical, intermittently anoxic basin. Assuming constant rates of oxidation of organic matter in equally spaced depth intervals below the pycnocline depth, the rate of denitrification was estimated to be about 62.0 µg-atom NO₃-N/liter/year. This rate is attributable to denitrification in the water column because a smaller rate was estimated for strata closer to the sediment water interface.Contribution No. 3193 from the Woods Hole Oceanographic Institution. Woods Hole, Massachusetts 02543. This study was supported in part by the National Science Foundation Grants GA 29303 and GB 6870. Reprints should be requested from the second author.     

Differentiation of sympatric populations of the band-rumped storm-petrel in the Galapagos Islands: an examination of genetics, morphology, and vocalizations

In each of at least two locations within the Galapagos Islands, breeding band-rumped storm-petrels (Oceanodroma castro) form two distinct populations that use the same colony site at separate times of the year for reproduction. Temporal segregation of these populations raises the possibility that they are reproductively isolated and represent cryptic species. We examined variation in mitochondrial DNA, morphology, and vocalizations of storm-petrel populations nesting 6 months apart on the islet of Plaza Norte in the Galapagos. Seasonal populations displayed low but significant levels of differentiation in the mitochondrial control region, five morphological variables, and one feature of male vocalizations. Breeding populations appear to have been separated for approximately 1700 years. Given the recent divergence date and relatively high effective population sizes (4000-5600 females each), seasonal populations are unlikely to be in genetic equilibrium. As a result, the low divergence estimate probably reflects historical association and not contemporary genetic exchange. These populations are not sufficiently differentiated to be considered cryptic species. However, they are probably in the early stages of divergence. Consequently, we recommend that cool- and hot season populations on Plaza Norte be recognized as separate management units.     

Presence of Chame Dormitator latifrom (Richardson, 1844) (Pisces: Eleotridae) in the Galapagos Islands, Ecuador

Six specimens of Dormitator latifrons caught in Laguna del Cementerio, Isabela Island, represent the first record of this species in the Galapagos Islands.     

Marine Ostracoda of the Galapagos Islands and Ecuador

Marine algae collected from rock pools on Hood, Fernandina and Mosquera, in the Galapagos Islands, have provided a fauna of 26 ostracod species of which 14 are new. One genus, belonging to the Hemicytheridae, is also new and appears to be endemic to the Islands. From two littoral algal samples collected from Punta Canoa and San Pedro beach, Ecuador, an assemblage of some nine species, four of which are new, is also described. Two ostracods: Touroconcha lapidiscola and Loxoconcha (Lox-ocorniculum) lenticuloides , are the only species so far known to be present both in the Galapagos Islands and off the coast of Central and South America. One species: Cytherelloidea praecipua recorded from off Tobago and Clipperton Islands may be present in the Galapagos but this has not definitely been confirmed. The evolution in the Gulf Coast/Caribbean region of several ostracods and their subsequent dispersal westwards is discussed.     

Are plant communities on the Canary Islands resistant to plant invasion?

Oceanic islands are renowned for their unique flora and high levels of endemism. Native island plants, however, are imperilled by non-native species that can become invasive by outcompeting natives. The threat of native island assemblages generally increases with isolation and the number of endemics featured, but also with human-associated disturbance and land use. Based on this, the Canary Island native plant systems should be highly threatened by invasives, similar to other oceanic islands globally. However, Canarian native plant systems are only weakly infiltrated and are rarely directly threatened by invasive plants. Further, highly disturbed areas, usually among the first colonized by invasives on islands, are recolonized here by natives. Based on this, we postulate four hypotheses (climatic filter, well-preservation status, human legacy and permanent colonization) for explaining this unusual behaviour of plant systems on the Canary Islands, providing an opportunity to understand the drivers and processes behind invasion into plant communities on islands.     

Implications of goat eradication on the survivorship of the Galapagos hawk

Non-native mammals cause ecological disasters in island ecosystems and their eradication is usually considered beneficial to native biodiversity. Goats (Capra hircus) were introduced to Santiago Island, Galapagos, Ecuador, in the early 1800s, and their numbers increased to about 100,000 by 1970. A goat eradication campaign initiated in 2002 was successful, eliminating the last individuals in 2006. To evaluate the effects of goat eradication, between 1998 and 2010 we studied the Galapagos hawk (Buteo galapagoensis) population on Santiago Island before, during, and after eradication. We used a 12-year data set in a capture–mark–recapture analysis to estimate the apparent survivorship of territorial adults in 33 breeding territories, and a 5-year data set to estimate the population sizes of the floater (non-territorial) fraction of the population. Juvenile floaters showed a drastic decline starting in 2006 and continuing in 2007, 2008, and 2010, which we attribute to the completion of goat eradication in 2006, and subsequent habitat changes. We found a significant decline in adult survivorship after the goat eradication program. Additionally, group size positively affected adult survivorship in this cooperatively polyandrous raptor, presumably reflecting the benefit of shared defense and offspring provisioning during harsher conditions. The changes in the hawk population after goat eradication are an example of unforeseen consequences of a restoration program, and we hypothesize that these changes are adjustments towards a new equilibrium under the current ecosystem characteristics and capacity. © 2012 The Wildlife Society.     

Citharichthys gnathus, a new species of paralichthyid flounder (Teleostei: Pleuronectiformes) from the Galapagos Islands, eastern pacific Ocean

A new paralichthyid flounder,Citharichthys gnathus, is described from 25 specimens from the Galapagos Islands. The new species strongly resemblesC. fragilis Gilbert, distributed in the Gulf of California and adjacent waters, in general appearance, and meristic and morphometric characters, but is distinguished from the latter by two adult characters, a remarkable bony knob at the anterior tip of the lower jaw and larger proportion of snout length in standard length.     

Revision of the family Pontocyprididae (Ostracoda), with new anchialine species and genera from Galapagos Islands

Iliffeoecia iliffei and Kareloecia woutersi are new argilloeciine and propontocyprididine genera and species from anchialine habitats in Galapagos Islands, whose specializations for interstitial or cryptic life show convergence with Comontocypris. Ekponlocypris, Schedopontocypris and the new genus Thomontocypris are removed from Propontocypris. Eighty-three living species of Pontocyprididae, for which the soft anatomy has been described, provide the basis for emended generic diagnoses and a revised classification.     

Tracing the colonization of Madeira and the Canary Islands by Drosophila subobscura through the study of the rp49 gene region

Nucleotide variation at the nuclear ribosomal protein 49 (rp49) gene region has been analysed by fine restriction mapping in a sample of 47 lines from a population from Madeira. Five restriction-site (out of 37 sites scored) and 3 length polymorphisms have been detected, resulting in 14 different haplotypes. This population shows less variation than both continental and Canary Island populations. The population from Madeira shows some differentiation from mainland populations, which does not favor the idea of extensive migration between the continent and Madeira. Chromosomal and restriction-map variation of the rp49 region in D. subobscura populations, together with data on sequence comparison of this nuclear region in D. guanche and D. madeirensis clearly indicate that the Canary Islands underwent at least two colonization events from the nearby continent. Although the data for Madeira are compatible with a single colonization event by a continental sample polymorphic for gene arrangements O₃ and O_{3 + 4}, an alternative scenario with at least two colonization events seems more likely.     

First record of a spawning aggregation for the tropical eastern Pacific endemic grouper Mycteroperca olfax in the Galapagos Marine Reserve

This study provides direct and indirect evidence of temporally and spatially consistent spawning aggregations for the grouper Mycteroperca olfax. Recently reported declines in population numbers, probably related to the direct targeting of aggregations by artisanal fishermen, highlight the urgent need for species‐specific management actions in the Galapagos Marine Reserve, such as minimum and maximum landing sizes, and the importance of protecting key aggregation sites with the declaration of no‐take areas and the establishment of total fishing bans during the reproductive season.     

Past,current, and future trends of red spiny lobster based on PCA with MaxEnt model in Galapagos Islands,Ecuador

In order to enhance in terms of accuracy and predict the modeling of the potential distribution of species, the integration of using principal components of environmental variables as input of maximum entropy (MaxEnt) has been proposed in this study. Principal components selected previously from the principal component analysis results performed in ArcGIS in the environmental variables was used as an input data of MaxEnt instead of raw data to model the potential distribution of red spiny lobster from the year 1997 to 2015 and for three different future scenarios 2020, 2050, and 2070. One set of six original environmental variables pertaining to the years 1997–2015 and one set of four variables for future scenarios were transformed independently into a single multiband raster in ArcGIS in order to select the variables whose eigenvalues explains more than 5% of the total variance with the purpose to use in the modeling prediction in MaxEnt. The years 1997 and 1998 were chosen to compare the accuracy of the model, showing better results using principal components instead of raw data in terms of area under the curve and partial receiver operating characteristic as well as better predictions of suitable areas. Using principal components as input of MaxEnt enhances the prediction of good habitat suitability for red spiny lobster; however, future scenarios suggest an adequate management by researches to elaborate appropriate guidelines for the conservation of the habitat for this valuable specie with face to the climate change.     

南麂列岛海洋自然保护区浮游动物的物种组成及其多样性

南麂列岛海洋自然保护区是我国首批五个海洋类自然保护区之一。作者根据2004年5月至2005年2月南麂列岛海域的4个季节的调查数据,分析了该区域浮游动物的种类组成、优势种类、生态类群与物种多样性等特征参数的季节变化。调查结果表明,共鉴定出浮游动物69种,隶属于6门12个类群,其中桡足类最多,占39.1%;可划分为5种生态类群,暖水性广布类群和暖温带近海类群为两种主要生态类群;出现优势种类15种,主要有中华哲水蚤(Calanussinicus)、精致真刺水蚤(Euchaetaconcinna)和肥胖箭虫(Sagittaenflata)等。多样性分析显示,除冬季外,其他三个季节Shannon-Wiener指数(H′)值均大于2,且秋季最高,达3.29。相关性分析表明,种类数与水温的正相关性非常显著。与1990年调查结果相比,春季和秋季种类类群及种类数有所减少,这与调查时水温变化有关。研究分析认为,种类组成的季节变化主要受到江浙沿岸流和台湾暖流的影响。     

Creating new evolutionary pathways through bioinvasion: the population genetics of brushtail possums in New Zealand

Rapid increases in global trade and human movement have created novel mixtures of organisms bringing with them the potential to rapidly accelerate the evolution of new forms. The common brushtail possum (Trichosurus vulpecula), introduced into New Zealand from Australia in the 19th century, is one such species having been sourced from multiple populations in its native range. Here, we combine microsatellite DNA‐ and GIS‐based spatial data to show that T. vulpecula originating from at least two different Australian locations exhibit a population structure that is commensurate with their introduction history and which cannot be explained by landscape features alone. Most importantly, we identify a hybrid zone between the two subspecies which appears to function as a barrier to dispersal. When combined with previous genetic, morphological and captive studies, our data suggest that assortative mating between the two subspecies may operate at a behavioural or species recognition level rather than through fertilization, genetic incompatibility or developmental inhibition. Nevertheless, hybridization between the two subspecies of possum clearly occurs, creating the opportunity for novel genetic combinations that would not occur in their natural ranges and which is especially likely given that multiple contact zones occur in New Zealand. This discovery has implications for wildlife management in New Zealand because multiple contact zones are likely to influence the dispersal patterns of possums and because differential susceptibility to baiting with sodium fluoroacetate between possums of different origins may promote novel genetic forms.     

The roles of demography and genetics in the early stages of colonization

Colonization success increases with the size of the founding group. Both demographic and genetic factors underlie this relationship, yet because genetic diversity normally increases with numbers of individuals, their relative importance remains unclear. Furthermore, their influence may depend on the environment and may change as colonization progresses from establishment through population growth and then dispersal. We tested the roles of genetics, demography and environment in the founding of Tribolium castaneum populations. Using three genetic backgrounds (inbred to outbred), we released individuals of four founding sizes (2–32) into two environments (natal and novel), and measured establishment success, initial population growth and dispersal. Establishment increased with founding size, whereas population growth was shaped by founding size, genetic background and environment. Population growth was depressed by inbreeding at small founding sizes, but growth rates were similar across genetic backgrounds at large founding size, an interaction indicating that the magnitude of the genetic effects depends upon founding population size. Dispersal rates increased with genetic diversity. These results suggest that numbers of individuals may drive initial establishment, but that subsequent population growth and spread, even in the first generation of colonization, can be driven by genetic processes, including both reduced growth owing to inbreeding depression, and increased dispersal with increased genetic diversity.     

香港索罟群岛植被与植物物种多样性研究

索罟群岛植被的次生性很强,以常绿灌丛为主,兼有次生性常绿阔叶林、滨海沙生灌草丛及少量半红树植物,其中灌木、草本植物种类丰富。群岛共有维管植物259种,隶属于85科207属,其中本土野生植物70科193属245种,包括2种受国家或地方保护的植物。其植物区系热带性质明显,56.47%的科属于泛热带分布,94.69%的属为热带分布类型,83.40%的种为热带分布,与邻近的广东内伶仃岛植物区系具有较高的相似性。受岛屿面积、海拔、隔离程度及人类活动等因素影响,群岛各岛屿的植物物种多样性各有特点,其中大鸦洲、小鸦洲植物种类最丰富。     

Bait Stations for Detection and Control of Alien Rats in Galapagos

ABSTRACT Alien rats have impacted native systems worldwide, yet wildlife managers lack techniques to efficiently monitor for rodent invasions where native rodents are present and to control alien rodents sympatric with native rodents. We tested the ability of vertical bait stations to exclude native rodents in the Galapagos Islands, Ecuador. Norway rats (Rattus norvegicus) appeared able to enter all station sizes, whereas black rats (R. rattus) were excluded from larger stations. The endemic rodents Oryzomys bauri and Nesoryzomys narboroughi were unable to enter bait stations of any size, but N. swarthi entered the smallest station. Differences in climbing technique contributed to the advantage of alien rodents over endemic species. Our technique provides wildlife managers in the Galapagos, and potentially other islands with native rodents, a means for early detection and control of alien rats.     

Past tree range dynamics in the Iberian Peninsula inferred through phylogeography and palaeodistribution modelling: A review

The forests in the Iberian Peninsula have been strongly influenced by past climatic changes, but reconstructing their historical distributions and dynamics is very difficult due to the complex climatic characteristics and relief of the region. Research disciplines such as phylogeography and species distribution modelling can describe the past range dynamics of individual tree species in relatively great detail and help elucidate how these species have reacted to climatic changes. Here we review phylogeographical and modelling studies from species representative of the major Iberian forest types and attempt to extract general trends from the diversity of individual species histories in the Peninsula. To date most studies focus on geographical range dynamics during the Pleistocene, but an increasing body of evidence shows that some species have also retained the genetic imprints of much more ancient processes. Many widespread Iberian species show a deep and often remarkably clear-cut divide between populations from the Mediterranean and from the Atlantic regions of the Iberian Peninsula, suggesting that both areas have independently sustained viable populations over extended periods. In fact, phylogeographical studies commonly find that species had several glacial refugia across the Iberian Peninsula. On the other hand, distribution models help identifying further suitable areas that could have sustained so far undetected refugia. Such studies are of interest for species conservation, because refugium populations are high-priority targets due to their long-term persistence and unique evolutionary trajectory. Overall, we conclude that palaeoecology, phylogeography and species distribution modelling have a great potential to inform each other because of their complementary perspectives and results. A true integration of these approaches is therefore fundamental for further progress in our understanding of past Iberian environments and the organisms they harboured.     

Invasion genetics of the Eurasian spiny waterflea: evidence for bottlenecks and gene flow using microsatellites

The Eurasian spiny waterflea (Bythotrephes longimanus) is a predacious zooplankter that has increased its range in Europe and is rapidly invading inland water-bodies throughout North America's Great Lakes region. To examine the genetics of these invasions, we isolated five microsatellite DNA loci with between 5 and 19 alleles per locus. We sampled three populations where B. longimanus has been historically present (Switzerland, Italy, and Finland) as well as an introduced European population (the Netherlands) and three North American populations (Lakes Erie, Superior, Shebandowan). Consistent with a bottleneck during colonization (i.e. founder effect), average heterozygosities of the four European populations ranged from 0.310 to 0.599, and were higher than that of three North American populations (0.151-0.220). Pairwise F(ST) estimates among North American populations (0.002-0.063) were not significantly different from zero and were much lower than among European populations (0.208-0.474). This is consistent with a scenario of high gene flow among North American populations relative to that of European ones. Contrary to an invasion bottleneck, however, Erie and Superior populations contained similar numbers of rare alleles as European populations. Assignment tests identified several migrant genotypes in all introduced populations (the Netherlands, Erie, Superior, Shebandowan), but rarely in native ones (Switzerland, Italy and Finland). A large number of genotypes from North America were assigned to our Italian population suggesting a second, previously unidentified, invasion source somewhere in the region of northern Italy. Together, our results support an invasion bottleneck for North American populations that has been largely offset by gene flow from multiple native sources, as well as gene flow among introduced populations.     

Interpreting colonization of the Calathus (Coleoptera: Carabidae) on the Canary Islands and Madeira through the application of the parametric bootstrap

The Canary Islands have proven to be an interesting archipelago for the phylogeographic study of colonization and diversification with a number of recent studies reporting evolutionary patterns and processes across a diversity of floral and faunal groups. The Canary Islands differ from the Hawaiian and Galapagos Islands by their close proximity to a continental land mass, being 110 km from the northwestern coast of Africa. This close proximity to a continent obviously increases the potential for colonization, and it can be expected that at the level of the genus some groups will be the result of more than one colonization. In this study we investigate the phylogeography of a group of carabid beetles from the genus Calathus on the Canary Islands and Madeira, located 450 km to the north of the Canaries and 650 km from the continent. The Calathus are well represented on these islands with a total of 29 species, and on the continent there are many more. Mitochondrial cytochrome oxidase I and II sequence data has been used to identify the phylogenetic relationships among the island species and a selection of continental species. Specific hypotheses of monophyly for the island fauna are tested with parametric bootstrap analysis. Data suggest that the Canary Islands have been colonized three times and Madeira twice. Four of these colonizations are of continental origin, but it is possible that one Madeiran clade may be monophyletic with a Canarian clade. The Calathus faunas of Tenerife and Madeira are recent in origin, similar to patterns previously reported for La Gomera, El Hierro, and Gran Canaria.