Anaphors in casual and controlled talks groups of Iranian EFL learners

By relying mainly on the accessibility approach to anaphora, this article intends to analyze the types, distributions and retrieval of anaphors in two forms of spoken discourse: casual and controlled talk. For the specific purposes of the study, twenty sophomore Iranian students were randomly selected to conduct the talks. The subjects were divided into two groups of casual and controlled talk. According to the settings and adopted topics, the overall casual talk group was further divided into two groups of dorm and academic talk. In the end, it was observed that as the talk situations vary, types, frequencies, distances, retrieval qualities and thematic structure (patterning) of anaphors undergo dramatic changes too. Further analyses of the obtained data show that the number of pronominal anaphors is by far more than NP anaphors in dorm casual talk whereas in academic casual talk the number of NP anaphors exceeds that of the former talk groups. However, the distribution of anaphors in the performance of controlled talk groups has shown to be more moderate with regard to the types of anaphors used in it. Overall, the distributional patterns of various anaphoric devices in different talk situations are considered to be a function of the speakers’ evaluation of the cognitive states of the listeners/addressees.
Average distances and frequencies of the different types of zero, pronominal, and NP anaphors have also been shown to undergo dramatic changes as talk situations vary.

Spatial and temporal drivers of small mammal distributions in a semi-arid environment : the role of rainfall, vegetation and life-history

A key task in ecology is to understand the drivers of animal distributions. In arid and semi-arid environments, this is challenging because animal populations show considerable spatial and temporal variation. An effective approach in such systems is to examine both broad-scale and long-term data. We used this approach to investigate the distribution of small mammal species in semi-arid ‘mallee’ vegetation in south-eastern Australia. First, we examined broad-scale data collected at 280 sites across the Murray Mallee region. We used generalized additive mixed models (GAMMs) to examine four hypotheses concerning factors that influence the distribution of individual mammal species at this scale: vegetation structure, floristic diversity, topography and recent rainfall. Second, we used long-term data from a single conservation reserve (surveyed from 1997 to 2012) to examine small mammal responses to rainfall over a period spanning a broad range of climatic conditions, including record high rainfall in 2011. Small mammal distributions were strongly associated with vegetation structure and rainfall patterns, but the relative importance of these drivers was species-specific. The distribution of the mallee ningaui Ningaui yvonneae, for example, was largely determined by the cover of hummock grass; whereas the occurrence of the western pygmy possum Cercartetus concinnus was most strongly associated with above-average rainfall. Further, the combination of both broad-scale and long-term data provided valuable insights. Bolam's mouse Pseudomys bolami was uncommon during the broad-scale survey, but long-term surveys showed that it responds positively to above-average rainfall. Conceptual models developed for small mammals in temperate and central arid Australia, respectively, were not, on their own, adequate to account for the distributional patterns of species in this semi-arid ecosystem. Species-specific variation in the relative importance of different drivers was more effectively explained by qualitative differences in life-history attributes among species.

Detecting range shifts among Australian fishes in response to climate change

One of the most obvious and expected impacts of climate change is a shift in the distributional range of organisms, which could have considerable ecological and economic consequences. Australian waters are hotspots for climate-induced environmental changes; here, we review these potential changes and their apparent and potential implications for freshwater, estuarine and marine fish. Our meta-analysis detected 300 papers globally on 'fish' and 'range shifts', with ∼7% being from Australia. Of the Australian papers, only one study exhibited definitive evidence of climate-induced range shifts, with most studies focussing instead on future predictions. There was little consensus in the literature regarding the definition of 'range', largely because of populations having distributions that fluctuate regularly. For example, many marine populations have broad dispersal of offspring (causing vagrancy). Similarly, in freshwater and estuarine systems, regular environmental changes (e.g. seasonal, ENSO cycles not related to climate change) cause expansion and contraction of populations, which confounds efforts to detect range 'shifts'. We found that increases in water temperature, reduced freshwater flows and changes in ocean currents are likely to be the key drivers of climate-induced range shifts in Australian fishes. Although large-scale frequent and rigorous direct surveys of fishes across their entire distributional ranges, especially at range edges, will be essential to detect range shifts of fishes in response to climate change, we suggest careful co-opting of fisheries, museum and other regional databases as a potential, but imperfect alternative. © 2011 CSIRO Open Access.