A comparison of the host preference of monarch butterflies (Danaus plexippus) for milkweed (Asclepias syriaca) over dog-strangler vine (Vincetoxicum rossicum)

Observations in the field indicate that monarch butterflies will oviposit on dog‐strangler vine, an invasive introduced species in the same family as milkweed (Asclepias spp.), the principal larval host of monarchs. The potential impact of this behaviour depends on the strength of the preference of monarch adults to oviposit on these two hosts and the relative ability of larvae to survive on each. We determined the preference for milkweed vs. dog‐strangler vine of ovipositing adults and first instar larvae in choice and no‐choice tests. We also compared the ability of larvae to consume, develop, and survive on either host. In the presence of both hosts, adults exhibited a strong preference to oviposit on milkweed over dog‐strangler vine (mean 80.7 eggs compared to 0.4 eggs over 48 h, respectively). In the absence of milkweed, adults ceased oviposition (mean 0.9 eggs in 48 h), but resumed oviposition when the dog‐strangler vine was replaced with milkweed (mean 99.1 eggs in 48 h). Given a choice between hosts over 24 h, 92% of larvae moved to milkweed leaves and consumed 3.94 cm² of milkweed leaves compared to 2% of larvae that moved to dog‐strangler vine and consumed negligible amounts of leaf material (0.01 cm²). Without a choice, larvae on dog‐strangler vine never consumed more than mean 0.02 cm² larva^?1 in a 24‐h period, did not develop beyond the first instar, and died within 96 h. We obtained no data in support of an effect of the presence of dog‐strangler vine on monarch butterfly populations.     

PHYLOGENETIC RELATIONSHIPS AMONG STREPTOPHYTES AS INFERRED FROM CHLOROPLAST SMALL AND LARGE SUBUNIT rRNA GENE SEQUENCES1

To gain insights into the phylogeny of charophytes and into their relationships with other green algae and bryophytes, we analyzed the chloroplast small and large subunit rRNA sequences of charophytes belonging to five orders (Charales, Coleochaetales, Desmidiales, Klebsormidiales, and Zygnematales), of chlorophytes from the four remaining classes of green algae, and of bryophytes representing the three classes reported in this group of land plants. We also probed the gene organization and intron content of the chloroplast rDNA operon in charophytes and bryophytes. The organization of this operon proved to be highly conserved, except in members of the Desmidiales and Zygnematales. Homologous group II introns were identified in the trnA(UGC) gene of all charophyte groups examined and in the trnI(GAU) gene of charophytes from all orders except the Desmidiales and Zygnematales. Phylogenetic analyses of concatenated rDNA sequences consistently placed the prasinophyte Mesostigma viride Lauterborn at the base of the Streptophyta and Chlorophyta, although alternative topologies positioning Mesostigma within the Streptophyta could not be rejected. A sister group relationship was unambiguously established between Chaetosphaeridium globosum (Nordstedt) Klebahn and members of the Coleochaetales. The Charales, Coleochaetales, Desmidiales, and Zygnematales were found to be monophyletic, and a sister group relationship was observed for the Desmidiales and Zygnematales. Although our analyses failed to resolve the branching order of the Coleochaetales, Charales, Desmidiales/Zygnematales, and bryophytes, they revealed that the problematic charophyte taxon Entransia fimbriata Hughes strongly clusters with Klebsormidium flaccidum (Kützing) Silva, Mattox et Blackwell to form a basal lineage relative to the other charophyte orders examined.     

Utility of 17-(allylamino)-17-demethoxygeldanamycin treatment for skeletal muscle injury

Repeated eccentric contractions can injure skeletal muscle and result in functional deficits that take several weeks to fully recover. The 70-kDa heat shock protein (Hsp70) is a stress-inducible molecular chaperone that maintains protein quality and plays an integral role in the muscle’s repair processes following injury. Here, we attempted to hasten this recovery by pharmacologically inducing Hsp70 expression in mouse skeletal muscle with 17-(allylamino)-17-demethoxygeldanamycin (17-AAG) (40 mg/kg) both prior to and throughout the first 7 days after an injurious bout of 150 maximal eccentric contractions. Hsp70 content in the injured skeletal muscle was strongly induced following the eccentric contractions and remained elevated over the next 7 days as the muscle underwent repair. Treatment with 17-AAG increased Hsp70 content ～fivefold; however, this was significantly less than that induced by the injury. Moreover, 17-AAG treatment did not recover the decrements to in vivo isometric torque production following the bout of eccentric contractions. Together, these findings demonstrate that although Hsp70 content was induced in the uninjured skeletal muscle, treatment of 17-AAG (40 mg/kg) was not a preventive measure to either reduce the severity of skeletal muscle damage or enhance functional recovery following a bout of maximal eccentric contractions.     

Nest success of northern bobwhite on managed and unmanaged landscapes in southeast Iowa

Range-wide declines in northern bobwhite populations (Colinus virginianus) have been attributed to concomitant loss of breeding habitat. Bobwhite management efforts to restore this habitat resource can be informed by empirical studies of associations between breeding success and multi-scale habitat attributes. We compared bobwhite nest success in 2 southern Iowa landscapes as a function of microhabitat and landscape composition. Lake Sugema Fish and Wildlife Area (LSWA) was managed to promote bobwhite recruitment, and Harrisburg Township (HT) was an adjacent landscape dominated by private agricultural production. Survival rate modeling based on telemetry data provided evidence for age-specific daily nest survival rate. Daily survival rates decreased as nest age increased, but the decline was more severe at HT. Nest survival at LSWA (S = 0.495, SE = 0.103) was nearly twice that on HT (S = 0.277, SE = 0.072). We found no evidence that habitat composition or spatial attributes within 210 m of a nest site significantly influenced nest success. Forb canopy at the nest site had a positive influence on nest success at HT but not at LSWA. We suggest nesting habitat with greater forb canopy cover will increase the opportunity for nesting success in landscapes with limited nesting habitat. © 2010 The Wildlife Society.     

The Possible Role of Resource Requirements and Academic Career-Choice Risk on Gender Differences in Publication Rate and Impact

Many studies demonstrate that there is still a significant gender bias, especially at higher career levels, in many areas including science, technology, engineering, and mathematics (STEM). We investigated field-dependent, gender-specific effects of the selective pressures individuals experience as they pursue a career in academia within seven STEM disciplines. We built a unique database that comprises 437,787 publications authored by 4,292 faculty members at top United States research universities. Our analyses reveal that gender differences in publication rate and impact are discipline-specific. Our results also support two hypotheses. First, the widely-reported lower publication rates of female faculty are correlated with the amount of research resources typically needed in the discipline considered, and thus may be explained by the lower level of institutional support historically received by females. Second, in disciplines where pursuing an academic position incurs greater career risk, female faculty tend to have a greater fraction of higher impact publications than males. Our findings have significant, field-specific, policy implications for achieving diversity at the faculty level within the STEM disciplines.