Anatomical features, monomer lignin composition and accumulation of phenolics in 1-year-old branches of the Mediterranean Cistus ladanifer L.

Mediterranean shrub species are described as having phenology, habitus , reproductive biology and anatomical alterations in certain tissues, allowing their survival during the dry season and protecting them from herbivory. Anatomical and chemical analyses were conducted in 1-year-old branches of Cistus ladanifer L. in order to investigate the role played by shoot structure in the adaptive strategies of this species in the Mediterranean environment. Results showed that both xylem and pith underwent lignification. Pith parenchyma cells had thickened walls, higher lignin content than xylem and different monomer composition. Xylem presented features aiding safe water transport. A large accumulation of phenolic substances was found in xylem, pith and cortical parenchyma. Observations reported in this paper suggest the occurrence of adaptive strategies in 1-year-old branches of C. ladanifer whose structural features: (1) allow mechanical reinforcement of tissues to withstand drought without suffering permanent damage; (2) favour safety rather than efficiency in water transport; (3) defend the plants from animal predation and pathogens by accumulating phenolics in various tissues, and (4) protect inner tissues against UV-B radiation through deposition of phenolic compounds in cortical layers.  © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society, 2007, 155 , 361–371.     

Evaluation of Potential Factors Predisposing Livestock to Predation by Jaguars

ABSTRACT Depredation of livestock by large carnivores is an important but poorly understood source of human-carnivore conflict. We examined patterns of livestock depredation by jaguars (Panthera onca) and pumas (Puma concolor) on a ranch-wildlife reserve in western Brazil to assess factors contributing to prey mortality. We predicted jaguars would kill a greater proportion of calves than yearling and adult cattle and that proximity to suitable habitat would increase mortality risk. We further speculated that exposure to predation risk would promote livestock grouping and increased movement distance. We recorded 169 cattle mortality incidents during 2003–2004, of which 19% were due to predation by jaguars and pumas. This level of mortality represented 0.2–0.3% of the total livestock holdings on the ranch. Jaguars caused most (69%) cattle predation events, and survival in allotments was lower for calves than for other age classes. Forest proximity was the only variable we found to explain patterns of livestock mortality, with predation risk increasing as distance to forest cover declined. Due to low predation risk, cattle movement patterns and grouping behavior did not vary relative to level of spatial overlap with radiocollared jaguars. The overall effect of predation on cattle was low and livestock likely constituted an alternative prey for large cats in our study area. However, selection of calves over other age cohorts and higher predation risk among cattle in proximity to forest cover is suggestive of selection of substandard individuals. Cattle ranchers in the Pantanal region may reduce cattle mortality rates by concentrating on losses due to nonpredation causes that could be more easily controlled.     

Hearing Range of White-Tailed Deer as Determined by Auditory Brainstem Response

Abstract: Basic knowledge of white-tailed deer (Odocoileus virginianus) hearing can improve understanding of deer behavior and may assist in the development of effective deterrent strategies. Using auditory brainstem response testing, we determined that white-tailed deer hear within the range of frequencies we tested, between 0.25–30 kilohertz (kHz), with best sensitivity between 4–8 kHz. The upper limit of human hearing lies at about 20 kHz, whereas we demonstrated that white-tailed deer detected frequencies to at least 30 kHz. This difference suggests that research on the use of ultrasonic (frequencies >20 kHz) auditory deterrents is justified as a possible means of reducing deer—human conflicts.     

Nest success of Lapwings Vanellus vanellus on organic and conventional arable farms in the Netherlands

Increasing agricultural intensification has put farmland bird populations under great stress. Although organically managed farms tend to have higher densities of farmland birds than conventionally managed holdings, differences in crop management may also lead to differences in breeding success. With the use of agrochemicals prohibited on organic farms, weeds are controlled using mechanical methods that may pose a threat to ground-nesting birds. This study compares the territory densities and nesting success of the Lapwing Vanellus vanellus on organic and conventional arable farms in the Netherlands. Territory densities were generally higher on organic farms, although in one year nesting success was lower on organic than on conventional farms. This was caused by higher nest loss resulting from farming activities on organic farms. There were no differences in predation rates. The results of this study show that breeding Lapwings may face potential threats on organic farms. To sustain or enhance Lapwing populations on these farms, additional conservation measures should be implemented.     

Detection of mitochondrial insertions in the nucleus (NuMts) of Pleistocene and modern muskoxen

Background  

Nuclear insertions of mitochondrial sequences (NuMts) have been identified in a wide variety of organisms. Trafficking of genetic material from the mitochondria to the nucleus has occurred frequently during mammalian evolution and can lead to the production of a large pool of sequences with varying degrees of homology to organellar mitochondrial DNA (mtDNA) sequences. This presents both opportunities and challenges for forensics, population genetics, evolutionary genetics, conservation biology and the study of DNA from ancient samples. Here we present a case in which difficulties in ascertaining the organellar mtDNA sequence from modern samples hindered their comparison to ancient DNA sequences.     

The auxin response factor,OsARF19, controls rice leaf angles through positively regulating OsGH3‐5 and OsBRI1

Auxin and brassinosteroid (BR) are important phytohormones for controlling lamina inclination implicated in plant architecture and grain yield. But the molecular mechanism of auxin and BR crosstalk for regulating lamina inclination remains unknown. Auxin response factors (ARFs) control various aspects of plant growth and development. We here report that OsARF19‐overexpression rice lines show an enlarged lamina inclination due to increase of its adaxial cell division. OsARF19 is expressed in various organs including lamina joint and strongly induced by auxin and BR. Chromatin immunoprecipitation (ChIP) and yeast one‐hybrid assays demonstrate that OsARF19 binds to the promoter of OsGH3‐5 and brassinosteroid insensitive 1 (OsBRI1) directing their expression. OsGH3‐5‐overexpression lines show a similar phenotype as OsARF19‐O1. Free auxin contents in the lamina joint of OsGH3‐5‐O1 or OsARF19‐O1 are reduced. OsGH3‐5 is localized at the endoplasmic retieulum (ER) matching reduction of the free auxin contents in OsGH3‐5‐O1. osarf19‐TDNA and osgh3‐5‐Tos17 mutants without erected leaves show a function redundancy with other members of their gene family. OsARF19‐overexpression lines are sensitive to exogenous BR treatment and alter the expressions of genes related to BR signalling. These findings provide novel insights into auxin and BR signalling, and might have significant implications for improving plant architecture of monocot crops.     

Predators marked with chemical cues from one prey have increased attack success on another prey species

1. To reduce the risk of being eaten by predators, prey alter their morphology or behaviour. This response can be tuned to the current danger if chemical or other cues associated with predators inform the prey about the risks involved. 2. It is well known that various prey species discriminate between chemical cues from predators that fed on conspecific prey and those that fed on heterospecific prey, and react stronger to the first. It is therefore expected that generalist predators are more successful in capturing a given prey species when they are contaminated with chemical cues from another prey species instead of cues from the same prey species. 3. Here, a generalist predatory mite was studied that feeds on thrips larvae as well as on whitefly eggs and crawlers. Mites were marked with cues (i.e. body fluids) of one of these two prey species and were subsequently offered thrips larva. 4. Predators marked with thrips cues killed significantly fewer thrips than predators marked with whitefly cues, even though the predator's tendency to attack was the same. In addition, more thrips larvae sought refuge in the presence of a predatory mite marked with thrips cues instead of whitefly cues. 5. This suggests that generalist predators may experience improved attack success when switching prey species.