Climate change effects on walnut pests in California

Increasing temperatures are likely to impact ectothermic pests of fruits and nuts. This paper aims to assess changes to pest pressure in California's US$0.7 billion walnut industry due to recent historic and projected future temperature changes. For two past (1950 and 2000) and 18 future climate scenarios (2041–2060 and 2080–2099; each for three General Circulation Models and three greenhouse gas emissions scenarios), 100 years of hourly temperature were generated for 205 locations. Degree‐day models were used to project mean generation numbers for codling moth (Cydia pomonella L.), navel orangeworm (Amyelois transitella Walker), two‐spotted spider mite (Tetranychus urticae Koch), and European red mite (Panonychus ulmi Koch). In the Central Valley, the number of codling moth generations predicted for degree days accumulated between April 1 and October 1 rose from 2–4 in 1950 to 3–5 among all future scenarios. Generation numbers increased from 10–18 to 14–24 for two‐spotted spider mite, from 9–14 to 14–20 for European red mite, and from 2–4 to up to 5 for navel orangeworm. Overall pest pressure can thus be expected to increase substantially. Our study did not include the possibility of higher winter survival rates, leading to higher initial pest counts in spring, or of extended pest development times in the summer, factors that are likely to exacerbate future pest pressure. On the other hand, initiation of diapause may prevent an extension of the season length for arthropods, and higher incidence of heat death in summer may constrain pest population sizes. More information on the impact of climate change on complex agroecological food webs and on the response of pests to high temperatures is needed for improving the reliability of projections.     

Associations between climate stress and coral reef diversity in the western Indian Ocean

Climatic–oceanographic stress and coral reef diversity were mapped in the western Indian Ocean (WIO) in order to determine if there were associations between high diversity coral reefs and regions with low‐to‐moderate climate stress. A multivariate stress model developed to estimate environmental exposure to stress, an empirical index of the coral community's susceptibility to stress, and field data on numbers of fish and corals taxa from 197 WIO sites were overlain to evaluate these associations. Exposure to stress was modeled from satellite data based on nine geophysical–biological oceanographic characteristics known to influence coral bleaching (i.e. temperature, light, and current variables). The environmental stress model and the coral community's susceptibility index were moderately correlated (r=?0.51) with southern and eastern parts of the WIO identified as areas with low environmental stress and coral communities with greater dominance of bleaching stress‐sensitive taxa. Numbers of coral and fish taxa were positive and moderately correlated (r=0.47) but high diversity regions for fish were in the north and west while diversity was highest for corals in central regions from Tanzania to northwestern Madagascar. Combining three and four of these variables into composite maps identified a region from southern Kenya to northern Mozambique across to northern–eastern Madagascar and the Mascarene Islands and the Mozambique–South Africa border as areas where low‐moderate environmental exposure overlaps with moderate‐high taxonomic diversity. In these areas management efforts aimed at maintaining high‐diversity and intact ecosystems are considered least likely to be undermined by climate disturbances in the near term. Reducing additional human disturbances, such as fishing and pollution, in these areas is expected to improve the chances for their persistence. These reefs are considered a high priority for increased local, national, and international management efforts aimed at establishing coral reef refugia for climate change impacts.     

Indirect effects of insect herbivory on leaf gas exchange in soybean

Herbivory can affect plant carbon gain directly by removing photosynthetic leaf tissue and indirectly by inducing the production of costly defensive compounds or disrupting the movement of water and nutrients. The indirect effects of herbivory on carbon and water fluxes of soybean leaves were investigated using gas exchange, chlorophyll fluorescence and thermal imaging. Herbivory by Popillia japonica and Helicoverpa zea (Boddie) caused a 20–90% increase in transpiration from soybean leaflets without affecting carbon assimilation rates or photosynthetic efficiency (Φ_PSII). Mechanical damage to interveinal tissue increased transpiration up to 150%. The spatial pattern of leaf temperature indicated that water loss occurred from injuries to the cuticle as well as from cut edges. A fluorescent tracer (sulforhodamine G) indicated that water evaporated from the apoplast approximately 100 µm away from the cut edges of damaged leaves. The rate of water loss from damaged leaves remained significantly higher than from control leaves for 6 d, during which time they lost 45% more water than control leaves (0.72 mol H₂O per cm of damaged perimeter). Profligate water loss through the perimeter of damaged tissue indicates that herbivory may exacerbate water stress of soybeans under field conditions.     

Tetranucleotide microsatellite loci from eastern bluebirds Sialia sialis

We describe primers and polymerase chain reaction (PCR) conditions to amplify 18 tetranucleotide microsatellite DNA loci in eastern bluebirds (Sialia sialis). The primers were tested using individuals from two study sites in Georgia and South Carolina. Among individuals from the Georgia population (n = 23), the primer pairs developed in this study yielded an average of 6.6 alleles per locus (range 2–12), an average observed heterozygosity of 0.56 (range 0.24–0.96) and an average polymorphic information content of 0.65 (range 0.3–0.86). Among individuals from the South Carolina population (n = 19), the primer pairs yielded an average of 5.8 alleles per locus (range 2–9), an average observed heterozygosity of 0.56 (range 0.05–0.86) and an average polymorphic information content of 0.63 (range 0.29–0.83).     

The effects of selection,drift and genetic variation on life‐history trait divergence among insular populations of natterjack toad,Bufo calamita

Although loss of genetic variation is frequently assumed to be associated with loss of adaptive potential, only few studies have examined adaptation in populations with little genetic variation. On the Swedish west coast, the northern fringe populations of the natterjack toad Bufo calamita inhabit an atypical habitat consisting of offshore rock islands. There are strong among‐population differences in the amount of neutral genetic variation, making this system suitable for studies on mechanisms of trait divergence along a gradient of within‐population genetic variation. In this study, we examined the mechanisms of population divergence using Q_ST–F_ST comparisons and correlations between quantitative and neutral genetic variation. Our results suggest drift or weak stabilizing selection across the six populations included in this study, as indicated by low Q_ST–F_ST values, lack of significant population × temperature interactions and lack of significant differences among the islands in breeding pond size. The six populations included in this study differed in both neutral and quantitative genetic variation. Also, the correlations between neutral and quantitative genetic variation tended to be positive, however, the relatively small number of populations prevents any strong conclusions based on these correlations. Contrary to the majority of Q_ST–F_ST comparisons, our results suggest drift or weak stabilizing selection across the examined populations. Furthermore, the low heritability of fitness‐related traits may limit evolutionary responses in some of the populations.     

Polar bear (Ursus maritimus) cub mortality at a den site in northern Alaska

In March 2009, we documented the death of one member of a triplet polar bear (Ursus maritimus) litter at its den site in the southern Beaufort Sea (SBS) of Alaska. We used a self-contained video camera unit to document activity between den emergence and departure. All three cubs showed low activity levels relative to other cubs observed, and one died within one week of den emergence. Necropsy confirmed that the dead cub had a low body weight and was malnourished. Capture later confirmed that the two surviving cubs were also undersized. Polar bear cub survival is influenced by many factors including litter size and sea ice conditions. Triplet litters are often smaller and suffer higher mortality rates than singletons and twins. This cub was not only a triplet but also born following 2 years of record minimum sea ice extent, both of which may have played a role in this cub’s demise.     

Systematic review of a new orb‐weaving spider genus (Araneae: Araneidae), with special reference to the Australasian‐Pacific and South‐East Asian fauna

The Australasian‐Pacific and South‐East Asian species of the new orb‐weaving spider genus Plebs with Plebs eburnus (Keyserling, 1886) as type species are revised. Following this study, Plebs includes a total of 22 species of which seven are here described new. Seven species are found in Australia, two in the Pacific region (New Caledonia, Vanuatu), and two in South‐East Asia (Papua New Guinea, The Philippines). Eleven Asian species are transferred to the new genus. Plebs represent comparatively small orb‐weaving spiders of c. 1.2–15.0 mm body length with a slightly elongated abdomen and humeral (shoulder) humps. Males of most species have two to three stout setae on the ventral side of their fourth coxae. Male pedipalps are characterized by the presence of a single macroseta on the patella, the presence of a paramedian apophysis as basal extension of the conductor, and an apical tegular protrusion. The female epigyne has a scape that is generally much longer than wide. It does not have a terminal pocket and is frequently broken off in a number of species. A phylogenetic analysis of 15 species of Plebs (those for which both sexes are known), 13 Australian/Pacific orb‐weaving spider species representing the most commonly collected clades with paramedian apophysis, three species of Nearctic Eriophora Simon, 1864, and Araneus diadematus Clerck, 1758, as outgroup, identified a single synapomorphy of Plebs based on 35 morphological and three behavioural characters: a distinct, inverted U‐shaped light pattern on the ventral side of the abdomen with two additional white spots anterolateral to the spinnerets. This analysis recovered a monophyletic clade of all Asian Plebs, suggesting a single colonization event of the genus that putatively originated in Australia. Most Plebs species appear to be active during the day. They build a regular orb‐web with vertical stabilimentum in grass and low shrubs. © 2012 The Linnean Society of London, Zoological Journal of the Linnean Society, 2012, 166 , 279–341.     

Evidence for spicule homology in calcareous and siliceous sponges: biminerallic spicules in Lenica sp. from the Early Cambrian of South China

Botting, J.P., Muir, L.A., Xiao, S., Li, X. & Lin, J.‐P. 2012: Evidence for spicule homology in calcareous and siliceous sponges: biminerallic spicules in Lenica sp. from the Early Cambrian of South China. Lethaia, Vol. 45, pp. 463–475. The relationships of the extant sponge classes, and the nature of the last common ancestor of all sponges, are currently unclear. Early sponges preserved in the fossil record differ greatly from extant taxa, and therefore information from the fossil record is critical for testing hypotheses of sponge phylogenetic relationships that are based on modern taxa. New specimens of the enigmatic sponge Lenica sp., from the Early Cambrian Hetang Biota of South China, exhibit an unusual spicule structure. Each spicule consists of a siliceous core with an axial canal, an organic outer layer and a middle layer interpreted to have been originally calcium carbonate. This finding confirms previous work suggesting the existence of biminerallic spicules in early sponges. Combined with data from other early sponges, the new findings imply that the two fundamental spicule structures of modern sponges were derived from a compound, biminerallic precursor. Spicules are therefore homologous structures in Calcarea and Silicea, and if sponges are paraphyletic with respect to Eumetazoa, then spicules may also have been a primitive feature of Metazoa. □Calcarea, Early Cambrian, Hetang Biota, phylogeny, Silicea, taphonomy.