Barbara York Main
Bio: Barbara York Main is an academic researcher from University of Western Australia. The author has contributed to research in topics: Mygalomorphae & Genus. The author has an hindex of 14, co-authored 35 publications receiving 582 citations.
TL;DR: This paper carried out a phylogeographic study of trapdoor spiders (Migidae: Moggridgea), a presumed Gondwanan lineage found in wet forest localities across southwestern Australia.
Abstract: Southwestern Australia has been recognized as a biodiversity hot spot of global significance, and it is particularly well known for its considerable diversity of flowering plant species. Questions of interest are how this region became so diverse and whether its fauna show similar diverse patterns of speciation. Here, we carried out a phylogeographic study of trapdoor spiders (Migidae: Moggridgea), a presumed Gondwanan lineage found in wet forest localities across southwestern Australia. Phylogenetic, molecular clock and population genetic analyses of mitochondrial (mtDNA) COI gene and ITS rRNA (internal transcribed spacer) data revealed considerable phylogeographic structuring of Moggridgea populations, with evidence for long-term (>3 million years) isolation of at least nine populations in different geographic locations, including upland regions of the Stirling and Porongurup Ranges. High levels of mtDNA divergence and no evidence of recent mitochondrial gene flow among valley populations of the Stirling Range suggest that individual valleys have acted as refugia for the spiders throughout the Pleistocene. Our findings support the hypothesis that climate change, particularly the aridification of Australia after the late Miocene, and the topography of the landscape, which allowed persistence of moist habitats, have been major drivers of speciation in southwestern Australia.
TL;DR: This work predicted a priori whether spiders with ten traits associated with survival, dispersal, reproduction, resource-utilization and microhabitat occupation would increase or decrease with post-fire age and tested these predictions using a direct and an indirect approach.
Abstract: 1 Developing a predictive understanding of how species assemblages respond to fire is a key conservation goal In moving from solely describing patterns following fire to predicting changes, plant ecologists have successfully elucidated generalizations based on functional traits Using species traits might also allow better predictions for fauna, but there are few empirical tests of this approach 2 We examined whether species traits changed with post-fire age for spiders in 27 sites, representing a chronosequence of 0-20 years post-fire We predicted a priori whether spiders with ten traits associated with survival, dispersal, reproduction, resource-utilization and microhabitat occupation would increase or decrease with post-fire age We then tested these predictions using a direct (fourth-corner on individual traits and composite traits) and an indirect (emergent groups) approach, comparing the benefits of each and also examining the degree to which traits were intercorrelated 3 For the seven individual traits that were significant, three followed predictions (body size, abundance of burrow ambushers and burrowers was greater in recently burnt sites); two were opposite (species with heavy sclerotisation of the cephalothorax and longer time to maturity were in greater abundance in long unburnt and recently burnt sites respectively); and two displayed response patterns more complex than predicted (abdominal scutes displayed a U-shaped response and dispersal ability a hump shaped curve) However, within a given trait, there were few significant differences among post-fire ages 4 Several traits were intercorrelated and scores based on composite traits used in a fourth-corner analysis found significant patterns, but slightly different to those using individual traits Changes in abundance with post-fire age were significant for three of the five emergent groups The fourth-corner analysis yielded more detailed results, but overall we consider the two approaches complementary 5 While we found significant differences in traits with post-fire age, our results suggest that a trait-based approach may not increase predictive power, at least for the assemblages of spiders we studied That said, there are many refinements to faunal traits that could increase predictive power
TL;DR: Findings indicate that O. navus may be vulnerable to desiccation and/or thermal stress, and thus survives better on sheltered walls, and is associated with high humidity, low air tempera- ture and shelter from sunlight and rainfall.
Abstract: To assess the relative impact of a range of habitat variables on spider abundance, field and laboratory experiments were conducted on populations of the urban wall spider Oecobius navus in suburban Perth, Western Australia. Habitat characteristics investigated were: substrate type, wind speed, rainfall, sunlight exposure, relative humidity, air temperature, substrate temperature, artificial lighting and prey type/abundance. In the field, O. navus was found to be associated with high humidity, low air tempera- ture and shelter from sunlight and rainfall. Oecobius navus was more abundant at sites with greater prey abundance. The most common prey item was the red meat ant Iridomyrmex chasei. Juvenile spiders were more abundant than adult spiders; however, patterns between spider abundance and habitat variables were similar for both adults and juveniles. Laboratory experiments showed that O. navus preferred to build webs on wooden substrates, and pitted limestone walls. These findings indicate that O. navus may be vulnerable to desiccation and/or thermal stress, and thus survives better on sheltered walls.
TL;DR: A molecular procedure for determining whether the overproduction of females results from a bias in the sperm or differential success of sperm in fertilization is described.
Abstract: Sex ratio data from embryos and adults are compared in the social thomisid Diaea socialis. The relative proportions of males and females do not differ significantly between the two data sets, indicating tha t a sex ratio bias already exists at the time of fertilization. A statistical comparison with published data for the theridiid Anelosimus eximiusshows a different ratio but similar pattern for the two types of data . A molecular procedure for determining whether the overproduction of females results from a bias in the sperm or differentia l success of sperm in fertilizationis described. In those social spiders where the adult sex rati o is known, it is female-biased (Buskirk 1981 ; Voll- rath 1986). However, Fisher's principle (Fisher 1930) predicts that selectionwill favor an equal parental investment in offspring of both sexes . It would follow, then, that any bias in sex rati o should result from forces acting after dispersal. On the basis of the correlation between sex rati o and social behavior it would seem reasonable t hypothesize that the two phenomena are in som e way causally linked. Skewed sox ratios have sim - ilarly been reported in colonies ofDiaea sociali s Main, with an observed male :female ratio o f 0.2126 (Main 1988).
TL;DR: In this paper, the authors examined two contrasting agro-political and agroeconomic frameworks within which ecological restoration currently operates in Austria and Western Australia, and concluded that differences in agropolitical priorities have resulted in diverging agro economic systems where producers are heavily subsidised (EU) or largely unsubsidised (WA).
Abstract: The restoration of ecosystems to stop biodiversity losses in agricultural landscapes has high priority in many regions of the world It does not take place in a vacuum but is nested in a socio-historical and agro-political context Austria and Western Australia (WA) are examples of old and newly impacted agricultural environments, and these are used to examine two contrasting agro-political and agro-economic frameworks within which ecological restoration currently operates WA is characterised by ancient, nutrient-impoverished, and degraded agricultural landscapes that have been under cultivation for some 100 years and support a low density rural population In Austria agriculture has been practised for some 7000 years and the European Union (EU) and its extensive funding system largely determine agro-political policies The paper concludes that: (1) differences in agro-political priorities have resulted in diverging agro-economic systems where producers are heavily subsidised (EU) or largely unsubsidised (WA); (2) diverging agro-political priorities result from differences in terms of land degradation; demographic characteristics, and duration of respective agriculture; (3) WA failed to develop a financial strategy aimed at ecological restoration for biodiversity conservation while Austria benefits from a EU-driven subsidy system to maintain biodiversity conservation; (4) the Landcare movement plays a significant role in the restoration of biodiversity in WA, but is largely absent in the EU; (5) different environmental and social histories demand different approaches to improve the economic frameworks within which ecological restoration is conducted in each region
TL;DR: It is suggested that the natural selection against large insertion/deletion is so weak that a large amount of variation is maintained in a population.
Abstract: The relationship between the two estimates of genetic variation at the DNA level, namely the number of segregating sites and the average number of nucleotide differences estimated from pairwise comparison, is investigated. It is found that the correlation between these two estimates is large when the sample size is small, and decreases slowly as the sample size increases. Using the relationship obtained, a statistical method for testing the neutral mutation hypothesis is developed. This method needs only the data of DNA polymorphism, namely the genetic variation within population at the DNA level. A simple method of computer simulation, that was used in order to obtain the distribution of a new statistic developed, is also presented. Applying this statistical method to the five regions of DNA sequences in Drosophila melanogaster, it is found that large insertion/deletion (greater than 100 bp) is deleterious. It is suggested that the natural selection against large insertion/deletion is so weak that a large amount of variation is maintained in a population.
TL;DR: It is unknown how the extensive European agri-environmental budget for conservation on farmland contributes to the policy objectives to halt biodiversity decline, and new research directions are identified addressing this important knowledge gap.
Abstract: Biodiversity continues to decline, despite the implementation of international conservation conventions and measures. To counteract biodiversity loss, it is pivotal to know how conservation actions affect biodiversity trends. Focussing on European farmland species, we review what is known about the impact of conservation initiatives on biodiversity. We argue that the effects of conservation are a function of conservation-induced ecological contrast, agricultural land-use intensity and landscape context. We find that, to date, only a few studies have linked local conservation effects to national biodiversity trends. It is therefore unknown how the extensive European agri-environmental budget for conservation on farmland contributes to the policy objectives to halt biodiversity decline. Based on this review, we identify new research directions addressing this important knowledge gap.
13 Feb 2014
TL;DR: Urban ecology: Science of Cities as mentioned in this paper explores the entire urban area: from streets, lawns, and parks to riversides, sewer systems, and industrial sites, and presents models, patterns, and examples from hundreds of cities worldwide.
Abstract: How does nature work in our human-created city, suburb, and exurb/peri-urb? Indeed how is ecology - including its urban water, soil, air, plant, and animal foundations - spatially entwined with this great human enterprise? And how can we improve urban areas for both nature and people? Urban Ecology: Science of Cities explores the entire urban area: from streets, lawns, and parks to riversides, sewer systems, and industrial sites. The book presents models, patterns, and examples from hundreds of cities worldwide. Numerous illustrations enrich the presentation. Cities are analyzed, not as ecologically bad or good, but as places with concentrated rather than dispersed people. Urban ecology principles, traditionally adapted from natural-area ecology, now increasingly emerge from the distinctive features of cities. Spatial patterns and flows, linking organisms, built structures, and the physical environment highlight a treasure chest of useful principles. This pioneering interdisciplinary book opens up frontiers of insight, as a valuable source and text for undergraduates, graduates, researchers, professionals, and others with a thirst for solutions to growing urban problems.