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Global declines in bird and arthropod abundance highlights the importance of understanding the role of food limitation and arthropod community composition for the performance of insectivorous birds. In this study, we link data on nestling diet, arthropod availability and nesting performance for the Coastal Cactus Wren (Campylorhynchus brunneicapillus sandiegensis), an at-risk insectivorous bird native to coastal southern California and Baja Mexico. We used DNA metabarcoding to characterize nestling diets and monitored 8 bird territories over two years to assess the relationship between arthropod and vegetation community composition and bird reproductive success. We document a discordance between consumed prey and arthropod biomass within nesting territories, in which Diptera and Lepidoptera were the most frequently consumed prey taxa but were relatively rare in the environment. In contrast other Orders (e.g., Hemiptera, Hymenoptera)were abundant in the environment but were absent from nestling diets. Accordingly, variation in bird reproductive success among territories was positively related to the relative abundance of Lepidoptera (but not Diptera), which were most abundant on 2 shrub species (Eriogonum fasciculatum, Sambucus nigra) of the 9 habitat elements characterized (8 dominant plant species and bare ground). Bird reproductive success was in turn negatively related to two invasive arthropods whose abundance was not associated with preferred bird prey, but instead possibly acted through harassment (Linepithema humile; Argentine ants) and parasite transmission or low nutritional quality (Armadillidium vulgare; "pill-bug"). These results demonstrate how multiple aspects of arthropod community structure can influence bird performance through complementary mechanisms, and the importance of managing for arthropods in bird conservation efforts.

The evolution of problematic plants, both weeds and invasives, is a topic of increasing interest. Plants that have evolved from domesticated ancestors have certain advantages for study. Because of their economic importance, domesticated plants are generally well-characterized and readily available for ecogenetic comparison with their wild descendants. Thus, the evolutionary history of crop descendants has the potential to be reconstructed in some detail. Furthermore, growing crop progenitors with their problematic descendants in a common environment allows for the identification of significant evolutionary differences that correlate with weediness or invasiveness. We sought well-established examples of invasives and weeds for which genetic and/or ethnobotanical evidence has confirmed their evolution from domesticates. We found surprisingly few cases, only 13. We examine our list for generalizations and then some selected cases to reveal how plant pests have evolved from domesticates. Despite their potential utility, crop descendants remain underexploited for evolutionary study. Promising evolutionary research opportunities for these systems are abundant and worthy of pursuit.

Removal of non-native plants is known to increase overall native cover within degraded communities that contain at least a small percentage of native plant cover. We investigated the mechanisms behind this pattern, asking whether removal of non-native annual species increases the density and species richness of the native community through increased seedling recruitment or through the growth of established native shrubs. We also investigated whether the effectiveness of non-native removal was influenced by region (coastal versus inland) and whether there was a threshold of native cover required for invasive removal to be effective. We established 13 study sites (7 coastal and 6 inland) located throughout the Nature Reserve of Orange County, CA, USA. Each degraded site contained four paired plots corresponding to a range of existing native plant cover: low 20–29%, medium-low 30–39%, medium-high 40–49%, and high cover 50–59% with one plot per pair subjected to non-native removal. We collected plant density, species richness, and established native shrub volume measurements to clarify the effectiveness of non-native removal. Non-native plant removal reduced non-native annual recruitment, increased that of native shrub seedlings, but had no impact on native forb recruitment. Non-native removal increased the number and reduced mortality of established native shrubs but did not influence shrub size. Native seedling density, species richness, and established native shrub number were highest inland, but coastal sites had larger adult shrubs. We found that non-native removal was most effective for increasing native density and species richness for degraded inland sites with less than 40% of existing native cover. The initial native cover did not affect established shrub volume or number. Our results confirm the importance of non-native plant removal in areas with medium-low or low native cover to increase native recruitment, species richness, adult shrub number, and to reduce established shrub mortality, especially during extreme drought. [ABSTRACT FROM AUTHOR]

Ecologists have explored community assembly through the framework of ecological filters, which predicts that species must overcome a series of challenges (i.e. pass through "filters") to successfully establish in a given community. In the context of restoration, these filters (dispersal, abiotic, and biotic) can be manipulated to alter the resulting plant community by favoring native species or disadvantaging non‐native invasive species. We conducted two studies manipulating assembly filters at two California grassland sites previously dominated by non‐native species. At Site 1, we explored how variations in sequential seeding of native grasses and forbs (to overcome dispersal and biotic filters caused by priority effects) influenced the resulting community. At Site 2, we explored how thatch removal (to overcome the abiotic filter of light limitation) and herbicide‐based weed control (to overcome the biotic filter of competition from non‐native species) influenced the addition of native forbs into a partially restored grassland. Native forbs at Site 1 did not suffer from arriving after grasses, but native grasses benefited when given 1 year priority over forbs. At Site 2, dethatching increased native forb cover in a high rainfall year. Herbicide application reduced non‐native grass cover in dethatched plots without negatively affecting native cover. Native forb and grass cover were significant predictors of non‐native grass cover. However, they accounted for only 29% of the variation observed, suggesting there are other influential factors not considered in this study. Our results suggest that forbs can be incorporated into established native grasslands more successfully after dethatching. [ABSTRACT FROM AUTHOR]

The process of induced DNA strand cleavage in the absence of oxygen has been found to release radicals by adding benzenethiyl radicals to dinucleotide derivatives. Kinetic experiments were used to perform the anerobic cleavage of DNA.

The article looks at the nesting capabilities of Cactus Wrens through nest boxes and cactus-like structures. The study was performed on the birds in Orange County, California through 13 structures and 32 boxes, where the birds were assessed in terms of nest usage and the efficiency of nest construction designs. Results of the study showed that 2 out of 32 next boxes enables Cactus Wrens to raise young and another box was utilized as a brood nest, while none of the birds did not use the cactus-like structures as breeding grounds, making the boxes as solutions for conservation of the wrens.

The maximum quantum yield for photosynthetic O2 evolution in red leaf coleus varieties having anthocyanin in their upper epidermis is much lower in green light and slightly lower in white light than in a green leaf variety lacking anthocyanin. A similar degree of photoinhibition occurred under excess visible light in the red versus green varieties; whereas, the red leaf varieties were less damaged by UV-B and UV-C radiation suggesting protection by anthocyanin in their epidermal tissue. [ABSTRACT FROM AUTHOR]