Species introductions of anthropogenic origins are a major aspect of rapid ecological change globally. Research on biological invasions has generated a large literature on many different aspects of this phenomenon. Here, we describe and categorize some aspects of this literature, to better understand what has been studied and what we know, mapping well-studied areas and important gaps. To do so, we employ the techniques of systematic reviewing widely adopted in other scientific disciplines, to further the use of approaches in reviewing the literature that are as scientific, repeatable, and transparent as those employed in a primary study. We identified 2398 relevant studies in a field synopsis of the biological invasions literature. A majority of these studies (58%) were concerned with hypotheses for causes of biological invasions, while studies on impacts of invasions were the next most common (32% of the publications). We examined 1537 papers in greater detail in a systematic review. Superior competitive abilities of invaders, environmental disturbance, and invaded community species richness were the most common hypotheses examined. Most studies examined only a single hypothesis. Almost half of the papers were field observational studies. Studies of terrestrial invasions dominate the literature, with most of these concerning plant invasions. The focus of the literature overall is uneven, with important gaps in areas of theoretical and practical importance.

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The purpose of our study was to prospectively study the splanchnic response to hypothermic and tepid cardiopulmonary bypass (CPB) using alphastat management of arterial blood-gas tensions. Twenty-four patients for elective CABG surgery were allocated randomly to tepid (35-36 degrees C) or hypothermic (30 degrees C) bypass groups. Measurements were made at four times: (1) baseline, (2) stable during CPB (inflow temperature = nasopharyngeal temperature) 30 degrees C for hypothermic patients, bypass +20 min for tepid patients, (3) 10 min before the end of bypass, (4) after bypass, skin closure. Both groups demonstrated a significant reduction in gastric intramucosal pH (pHim) from time 1 to time 4 and there was no difference in the incidence of a low pHim between the tepid and cold groups (4/12 vs 3/12; ns) at time 4. pHim was significantly lower in the tepid groups at time 3 (P = 0.03) but this discrepancy may have been because of an artefactually high pHim in the cold group. There was a significantly higher incidence of postoperative non-cardiac complications in patients who had a low pHim at time 4 (P = 0.0008). Therefore, we conclude that although the temperature during CPB had a transient effect on pHim it is unlikely to be a major determinant in the pathogenesis of gut mucosal hypoperfusion after bypass.