Comparing two methods for estimating floral resource availability for insect pollinators in semi-natural habitats

Pollinator and flowering plant interactions play a critical role in maintaining most terrestrial ecosystems, including agroecosystems. Although estimates of floral resource availability are essential to understand plant–pollinator relationships, no generally accepted methodology exists to date. We compared two methods for sampling floral resources in a single meadow. About every three days, we recorded species lists of insect-pollinated plants with abundance categories assigned to each species (hereafter referred to as scanning) and we counted the flowering shoots in 36 2 × 2 m quadrats (hereafter quadrat sampling). These methods were compared with respect to (i) the number of species detected, (ii) estimated floral resource abundance, and (iii) temporal changes in flowering. With scanning, we found more potential nectar-plant species and species were found earlier than with quadrat sampling. With the latter, abundant species were found with higher probability than the scarce. Flower abundances were correlated between the two methods. We predicted that a cover of 6.3 ± 3.6% should be used for an appropriate estimate of flower abundance in our study site, although the optimal cover probably varies across different habitats. Furthermore, flower abundance changed 6% per day compared to the flowering peak. Overall, scanning seems to be more appropriate for detecting presence and the timing of species, while quadrats may provide higher resolution for abundance estimates. Increased sampling coverage and frequency may enhance research accuracy and using scanning and quadrat sampling simultaneously may help to optimize research effort. We encourage further development of sampling protocols.     

Temperature dependence on the pesticide sampling rate of polar organic chemical integrative samplers (POCIS)

Laboratory experiments were performed to determine the sampling rates of pesticides for the polar organic chemical integrative samplers (POCIS) used in Japan. The concentrations of pesticides in aquatic environments were estimated from the accumulated amounts of pesticide on POCIS, and the effect of water temperature on the pesticide sampling rates was evaluated. The sampling rates of 48 pesticides at 18, 24, and 30 °C were obtained, and this study confirmed that increasing trend of sampling rates was resulted with increasing water temperature for many pesticides.     

Copulatory plugs inhibit the reproductive success of rival males

Ejaculated proteins play important roles in reproductive fitness. In many species, seminal fluid coagulates and forms what has been referred to as a copulatory plug in the female's reproductive tract. In mice, previous work demonstrated that knockout males missing a key seminal fluid protein were unable to form a plug and less successful at siring litters in noncompetitive matings (one female, one male), probably the result of reduced sperm transport or insufficient stimulation of the female. Here, we extend these previous studies to competitive matings (one female, two males) and make two key insights. First, when first males were unable to form a plug, they lost almost all paternity to second males to mate. Thus, the copulatory plugs of second males could not rescue the reduced fertility of first males. Second, we showed that the copulatory plug of first males effectively blocked fertilization by second males, even if first males were vasectomized. Taken together, our experiments demonstrated that first males lost almost all paternity if they never formed a plug. We discuss our results in the context of natural populations, where in spite of the strong effects seen here, pregnant female mice regularly carry litters fertilized by more than one male.     

Severe extinction and rapid recovery of mammals across the Cretaceous–Palaeogene boundary,and the effects of rarity on patterns of extinction and recovery

The end‐Cretaceous mass extinction ranks among the most severe extinctions of all time; however, patterns of extinction and recovery remain incompletely understood. In particular, it is unclear how severe the extinction was, how rapid the recovery was and how sampling biases might affect our understanding of these processes. To better understand terrestrial extinction and recovery and how sampling influences these patterns, we collected data on the occurrence and abundance of fossil mammals to examine mammalian diversity across the K‐Pg boundary in North America. Our data show that the extinction was more severe and the recovery more rapid than previously thought. Extinction rates are markedly higher than previously estimated: of 59 species, four survived (93% species extinction, 86% of genera). Survival is correlated with geographic range size and abundance, with widespread, common species tending to survive. This creates a sampling artefact in which rare species are both more vulnerable to extinction and less likely to be recovered, such that the fossil record is inherently biased towards the survivors. The recovery was remarkably rapid. Within 300 000 years, local diversity recovered and regional diversity rose to twice Cretaceous levels, driven by increased endemicity; morphological disparity increased above levels observed in the Cretaceous. The speed of the recovery tends to be obscured by sampling effects; faunas show increased endemicity, such that a rapid, regional increase in diversity and disparity is not seen in geographically restricted studies. Sampling biases that operate against rare taxa appear to obscure the severity of extinction and the pace of recovery across the K‐Pg boundary, and similar biases may operate during other extinction events.     

Mate choice and the operational sex ratio: an experimental test with robotic crabs

The operational sex ratio (OSR: sexually active males: receptive females) predicts the intensity of competition for mates. It is less clear, however, under what circumstances, the OSR predicts the strength of sexual selection – that is, the extent to which variation in mating success is attributable to traits that increase the bearer's attractiveness and/or fighting ability. To establish causality, experiments that manipulate the OSR are required. Furthermore, if it is possible to control for any OSR‐dependent changes in the chosen sex (e.g. changes in male courtship), we can directly test whether the OSR affects the behaviour of the choosing sex (e.g. female choice decisions). We conducted female mate choice experiments in the field using robotic models of male fiddler crabs (Uca mjoebergi). We used a novel design with two females tested sequentially per trial. As in nature, the choice of the first female to mate therefore affected the mates available to the next female. In general, we detected significant sexual selection due to female choice for ‘males’ with larger claws. Importantly, the strength of sexual selection did not vary across five different OSR/density treatments. However, as the OSR decreased (hence the number of available males declined), females chose the ‘males’ with the largest claws available significantly more often than expected by chance. Possible reasons for this mismatch between the expected and observed effects of the OSR on the strength of sexual selection are discussed.     

Bioaerosol biomonitoring: Sampling optimization for molecular microbial ecology

Bioaerosols (or biogenic aerosols) have largely been overlooked by molecular ecologists. However, this is rapidly changing as bioaerosols play key roles in public health, environmental chemistry and the dispersal ecology of microbes. Due to the low environmental concentrations of bioaerosols, collecting sufficient biomass for molecular methods is challenging. Currently, no standardized methods for bioaerosol collection for molecular ecology research exist. Each study requires a process of optimization, which greatly slows the advance of bioaerosol science. Here, we evaluated air filtration and liquid impingement for bioaerosol sampling across a range of environmental conditions. We also investigated the effect of sampling matrices, sample concentration strategies and sampling duration on DNA yield. Air filtration using polycarbonate filters gave the highest recovery, but due to the faster sampling rates possible with impingement, we recommend this method for fine ‐scale temporal/spatial ecological studies. To prevent bias for the recovery of Gram‐positive bacteria, we found that the matrix for impingement should be phosphate‐buffered saline. The optimal method for bioaerosol concentration from the liquid matrix was centrifugation. However, we also present a method using syringe filters for rapid in‐field recovery of bioaerosols from impingement samples, without compromising microbial diversity for high ‐throughput sequencing approaches. Finally, we provide a resource that enables molecular ecologists to select the most appropriate sampling strategy for their specific research question.