Prediction of the age at onset in spinocerebellar ataxia type 1, 2, 3 and 6
Sophie Tezenas du Montcel
Bart P. van de Warrenburg
Roberto Di Fabio
- Background The most common spinocerebellar ataxias (SCA)—SCA1, SCA2, SCA3, and SCA6—are caused by (CAG)n repeat expansion. While the number of repeats of the coding (CAG)n expansions is correlated with the age at onset, there are no appropriate models that include both affected and preclinical carriers allowing for the prediction of age at onset.
Methods We combined data from two major European cohorts of SCA1, SCA2, SCA3, and SCA6 mutation carriers: 1187 affected individuals from the EUROSCA registry and 123 preclinical individuals from the RISCA cohort. For each SCA genotype, a regression model was fitted using a log-normal distribution for age at onset with the repeat length of the alleles as covariates. From these models, we calculated expected age at onset from birth and conditionally that this age is greater than the current age.
Results For SCA2 and SCA3 genotypes, the expanded allele was a significant predictor of age at onset (−0.105±0.005 and −0.056±0.003) while for SCA1 and SCA6 genotypes both the size of the expanded and normal alleles were significant (expanded: −0.049±0.002 and −0.090±0.009, respectively; normal: +0.013±0.005 and −0.029±0.010, respectively). According to the model, we indicated the median values (90% critical region) and the expectancy (SD) of the predicted age at onset for each SCA genotype according to the CAG repeat size and current age.
Conclusions These estimations can be valuable in clinical and research. However, results need to be confirmed in other independent cohorts and in future longitudinal studies.
Aztec introduction of the great-tailed grackle in ancient Mesoamerica: Formal defense of the Sahaguntine historical account
Paul D. Haemig
- The historical account of Aztec Emperor Auitztol’s introduction of the great-tailed grackle Quiscalus mexi¬canus into the Valley of Mexico (1486–1502) is significant because it documents human translocation of wild birds in Mexico over 500 years ago, before the Spanish Conquest of that land. In the present paper, which defends the account from writings that dispute it, I first review the evidence of how the account was obtained and show that its many details are consistent with what is known from other sources about both the great-tailed grackle and the Aztecs (Nahuas). I then review and examine all published criticisms of the account and explain in detail why they are wrong. The critics have to date presented no persuasive evidence to support their speculation that the Aztecs confused, or might have confused, a natural invasion for an introduction. In contrast to these critics, Bernardino de Sahagún’s research group in the 1500s presented a highly credible, peer-reviewed historical account that documented Aztec introduction of the great-tailed grackle. The pioneering work of these Renaissance Mexican scholars continues to stand as one of the most important records of invasive alien species introduction in ancient times.
Invasion of yellow crazy ant Anoplolepis gracilipes in a Seychelles UNESCO palm forest
Christopher N. Kaiser-Bunbury
- The mature palm forest of the Vallée de Mai, a UNESCO World Heritage Site, on the Seychelles island of Praslin, is a unique ecosystem containing many endemic species, including the iconic coco de mer palm Lodoicea maldivica. In 2009, the invasive yellow crazy ant Anoplolepis gracilipes was recorded for the first time within the palm forest, raising concern about its potential impacts on the endemic fauna. This research aimed to: (1) assess the current distribution and spread of A. gracilipes within the palm forest; (2) identify environmental variables that are linked to A. gracilipes distribution; and (3) compare endemic species richness and abundance in A. gracilipes invaded and uninvaded areas. Anoplolepis gracilipes was confined to the north-east of the site and remained almost stationary between April 2010 and December 2012, with isolated outbreaks into the forest. Infested areas had significantly higher temperature and humidity and lower canopy cover. Abundance and species richness of the endemic arboreal fauna were lower in the A. gracilipes invaded area. Molluscs were absent from the invaded area. The current restricted distribution of A. gracilipes in this ecosystem, combined with lower abundance of endemic fauna in the invaded area, highlight the need for further research to assess control measures and the possible role of biotic resistance to the invasion of the palm forest by A. gracilipes.
Environmental and economic impact of alien terrestrial arthropods in Europe
- In the last few decades, the abundance and importance of invasive alien species have grown continuously due to the undiminished growth of global trade. In most cases, arthropod introductions were unintended and occurred as hitchhikers or contaminants. Alien arthropods can have significant environmental impacts and can be economically costly. To measure these impacts, we expand a generic impact scoring system initially developed for mammals and birds, and applied it to terrestrial arthropods. It consists of six environmental impact categories and six economic impact categories, each with five impact levels. Information on impact was derived from an intensive analysis of published scientific literature. The scoring of the 77 most widely distributed arthropod species alien to Europe revealed the mite Varroa destructor as the most harmful species, followed by the Chinese longhorn beetle Anoplophora chinensis and the Argentine ant Linepithema humile. The highest environmental impact is through herbivory, disease transmission, and ecosystem impacts. The highest economic impact is on agriculture and human infrastructure and administration. The generic impact scoring system allows the impact scores of vertebrates and arthropods to be compared, thus serving as a background for the decision making processes of policy makers and stakeholders.
Forty years of experiments on aquatic invasive species: are study biases limiting our understanding of impacts?
Mads S. Thomsen
Julian D. Olden
James E. Byers
John F. Bruno
Brian R. Silliman
David R. Schiel
- Invasions by non-native species are a threat to biodiversity because invaders can impact native populations, communities and entire ecosystems. To manage this threat, it is necessary to have a strong mechanistic understanding of how non-native species affect local species and communities. We reviewed 259 published papers (1972–2012) that described field experiments quantifying the impact of aquatic nonnative species, to examine whether various types of study biases are limiting this understanding. Our review revealed that invasion impacts had been experimentally quantified for 101 aquatic non-native species, in all major freshwater and marine habitats, on all continents except Antarctica and for most higher taxonomic groupings. Over one-quarter (26%) of studies included tests for impacts on local biodiversity. However, despite this extensive research effort, certain taxa, habitats and regions remain poorly studied. For example, of the over one hundred species examined in previous studies, only one was a marine fish and only six were herbivores. Furthermore, over half (53%) of the studies were from the USA and two-thirds (66%) were from experiments conducted in temperate latitudes. By contrast, only 3% of studies were from Africa and <2% from high latitudes. We also found that one-fifth (20%) of studies were conducted in estuaries, but only 1% from coral reefs. Finally, we note that the standard procedure of pooling or not reporting non-significant treatments and responses is likely to limit future synthetic advancement by biasing meta-analysis and severely limiting our ability to identify non-native species with none or negligible ecological impacts. In conclusion, a future focus on poorly-studied taxa, habitats and regions, and enhanced reporting of results, should improve our understanding and management of impacts associated with aquatic non-native species.
The Global Garlic Mustard Field Survey (GGMFS): challenges and opportunities of a unique, large-scale collaboration for invasion biology
Robert I. Colautti
Steven J. Franks
Ruth A. Hufbauer
Peter M. Kotanen
James E. Byers
- To understand what makes some species successful invaders, it is critical to quantify performance differences between native and introduced regions, and among populations occupying a broad range of environmental conditions within each region. However, these data are not available even for the world’s most notorious invasive species. Here we introduce the Global Garlic Mustard Field Survey, a coordinated distributed field survey to collect performance data and germplasm from a single invasive species: garlic mustard (Alliaria petiolata) across its entire distribution using minimal resources. We chose this species for its ecological impacts, prominence in ecological studies of invasion success, simple life history, and several genetic and life history attributes that make it amenable to experimental study. We developed a standardised field survey protocol to estimate population size (area) and density, age structure, plant size and fecundity, as well as damage by herbivores and pathogens in each population, and to collect representative seed samples. Across four years and with contributions from 164 academic and non-academic participants from 16 countries in North America and Europe thus far, we have collected 45,788 measurements and counts of 137,811 plants from 383 populations and seeds from over 5,000 plants. All field data and seed resources will be curated for release to the scientific community. Our goal is to establish A. petiolata as a model species for plant invasion biology and to encourage large collaborative studies of other invasive species.
Fiel notes of two hunters for Nehalennia speciosa in boggy Vasyugan Plain, West Siberia
Oleg E. Kosterin
- In July 2005, Rafal Bernard requested Oleg Kosterin to collect some samples of Nehalennia speciosa from West Siberia for a DNA analysis. Oleg replied that so far he had only seen one individual of this species 25 years ago, but asked in which habitats it should be sought for exactly. Rafal sent him a draft of his paper (Bernard & Wildermuth, 2005) devoted to this subject. Having read it, Oleg came to the conclusion that this habitat (shallow water with Sphagnum and Carex limosa or C. lasiocarpa) might occupy the largest area in the world just in the boggy West Siberian Plain. Personal consultation with the geobotanist Dr. Nikolai Lashchinskii confirmed this notion. Then an almost automatic supposition followed that this area may serve as the main reservoir of N. speciosa, considered a local and endangered species in Western and Central Europe. At the same time, the existing records of N. speciosa from West Siberia were remarkably scarce. It was known from the Khanty-Mansi Autonomous Region (basins of the Tura and Konda Rivers), a small number of records from North Altai and adjacent areas north of it, a record from the steppe zone of Novosibirsk Province (Karasuk), a record in the basin of the Tuba River (Krasnoyarskii Krai), and a dubious old record from Omsk (see the map in Belyshev (1973) and a review in Bernard & Wildermuth (2005)). There was no record from the boggy Irtysh-Ob’ interfluve, where we would expect the species to flourish. This could be explained by the lack of attention by odonatologists to that interesting area. In these circumstances, the project of a special expedition(-s) was put forward, aimed to check the presence, pattern of distribution, abundance and habitat preferences of N. speciosa in these areas. For a decisive expedition we chose the Vasyugan Bog, the largest bog in the world, more precisely its north-eastern margin where we could find a good base in Plotnikovo village, Bakchar District, Tomsk Province.
Untangling some taxonomic riddles on damselfly genera (Zygoptera) from the neotropical region
Natalia von Ellenrieder
Rosser W. Garrison
- Examination of type material deposited in the IRSNB (Royal Belgian Institute of Natural Sciences, Brussels, Belgium) and in the BMNH (British Museum of Natural History, London, Great Britain) allowed us to solve taxonomic riddles regarding several damselfly (Zygoptera) genera from the neotropical region. We provide notes on the status of several types, and introduce the following new synonymies: Argia huallaga Fraser, 1946 = A. adamsi Calvert, 1902; Argia makoka Fraser, 1946 = A. kokama Fraser, 1946; Argia mollusca Fraser, 1946 = A. collata Selys, 1865; Argia trifoliata Fraser, 1946 = A. variegata Förster, 1914; Argia umbriaca Fraser, 1946 = A. indicatrix Calvert, 1902; Amphiagrion amphion Selys, 1876 = Ischnura verticalis (Say, 1840); a new combination: Oxyagrion cardinalis Fraser, 1946 to Leptobasis cardinalis (Fraser, 1946); and three lectotype designations (for Acanthagrion gracile race? lancea Selys, 1876, Acanthagrion trimaculatum Selys, 1876, and Leptagrion flammeum Selys, 1876).
Corduliochlora gen. nov. from the Balkans (Odonata: Corduliidae)
- The adult morphology of the recently established species Somatochlora borisi Marinov, 2001 is outlined. The species has a unique combination of features, especially when compared to representatives of the two closest European genera, Cordulia Leach, 1815 and Somatochlora Selys, 1871 but also compared to other Holarctic genera and species within the Corduliinae (sensu Garrison et al. 2006). The extent of these morphological differences suggests that the species can not be assigned to any of the extant genera, and therefore the new genus Corduliochlora is being established.
Colonization of Brazil by the cattle egret (Bubulcus ibis) revealed by mitochondrial DNA
Sílvia Nassif Del Lama
- The cattle egret (Bubulcus ibis) has recently colonized Brazil. This process offers an excellent opportunity for the study of colonization and dispersal patterns across extensive areas by non-native birds. The aims of the present investigation were a) to determine the genetic diversity of the cattle egret in Brazil and Africa, b) evaluate genetic differentiation between populations in different regions of Brazil and Africa, and c) detect genetic signs of demographic expansion in these two areas. Mitochondrial DNA (mtDNA) Control Region (CR) sequences were obtained from 112 cattle egrets in four Brazilian and four African (Kenya, Ghana and Nigeria) populations. Genetic diversity (H, h, θs) and population structure (AMOVA, Fst) were assessed and the populations were tested for signs of recent demographic expansion. A total of 35 haplotypes were found: 22 exclusive to Africa, 10 exclusive to Brazil and three shared by both samples. The degree of genetic diversity, determined by mtDNA analysis, was similar between Brazil and Africa, demonstrating that the successful colonization of the non-native area occurred with no significant loss of diversity. The pairwise Fst values among the Brazilian and African populations were all significantly different. The population in southern Brazilian exhibited the lowest degree of differentiation with respect to the African population, followed by the southeastern and northeastern populations of the country. The genetic differentiation data suggest that the colonization of Brazil by the cattle egret began in the southern region and expanded to the southeastern and northeastern regions of the country. This genetic differentiation pattern is in accordance with the higher number of cattle per grazing area in southern Brazil, which may have favored the onset of the successful establishment of the species. The findings indicate that mtDNA genetic diversity was retained during the colonization process and colonization began in the southern region of the country. Moreover, signs of demographic expansion were detected in the African sample.