Development and Validation of a Wing Key to Improve Harvest Management of Alcids in the Northwest Atlantic

Abstract: Murres (thick-billed [Uria lomvia] and common [U. aalge]) are legally hunted along the coast of Newfoundland and Labrador, Canada. Razorbills (Alca torda) are also incidentally taken. Only irregular estimates of the total murre harvest are available, so a tool to derive estimates of age- and species-specific harvest is required to effectively monitor the hunt and manage a sustainable harvest. We collected 293 murre and razorbill wings from hunters between 1999–2004, with the goal of identifying wing characteristics that could be used to discriminate age and species. We found that murres and razorbills could be reliably aged (first-yr vs. older) on the basis of molt limits of greater wing coverts. Using a discriminant function (DF) incorporating length of the first primary and second secondary feather, we classified 95–96% of common murres and 99–100% of thick-billed murres correctly to species. First-year thick-billed and common murres also differed in number of pale secondary coverts (median = 12 and 3, respectively), providing another species-specific trait. We developed a key to age and assign species based on these results. We assessed applicability and accuracy of the wing-key with novice observers, who differentiated between murre and razorbill wings using feather-pattern coloration with high accuracy (95 ± 9%) and were able to differentiate between the 2 murres species using 3 techniques: visual assessment of wing shape (83 ± 14% accuracy), the DF (94 ± 6%), and number of worn secondary coverts for first-year birds only (83 ± 5%). Experience increased success rates of aging and species classification using wing shape and number of worn secondary coverts but not using the DF. Despite differences in measurement accuracy and repeatability among observers, the DF proved to be robust. Our results will facilitate implementation of a species composition survey for the murre hunt and will improve identification rates of carcasses found during beached bird surveys in the Northwest Atlantic, aiding in monitoring of alcid populations vulnerable to anthropogenic activities.     

Holothurian faunal changes at the Triassic-Jurassic boundary

The diversity pattern of holothurian echinoderms during the late Triassic-early Jurassic is quantitatively analysed to examine the effect of different taxonomic approaches. Whereas sclerite morphospecies indicate major faunal change during the Norian with significant extinction in the Upper Norian. changes are less pronounced for parafamilies and least for biologically based groups. Perceived diversity patterns are subject to bias. including a significant effect of relative research effort on morphospecies and parafamily data. A large proportion of Lazarus taxa in the Rhaetian-Hettangian indicates a sampling problem due to preservational or geographic bias. * Holothurian. Norian, Rhaetian, Hettangian, taxonomic diversity, origination, extinction .     

Gland Cells in Resin Canal Epithelia in Guayule (Parthenium argentatum) in Relation to Resin and Rubber Production

Schizogenous resin canals develop in the pith and cortex ofthe primary stem tissue in guayule (Parthenium argentatum Gray).In secondary tissue concentric rings of resin canals are producedfrom derivatives of the vascular cambium. Both resin and rubberaccumulate in the epithelial cells of the canals. These havethe characteristics of gland cells. Resin is secreted into thecanals and rubber accumulates in the surrounding parenchymacells as well as the gland cells, especially in winter. Younggland cells contain modified plastids and smooth tubular endoplasmicreticulum. These organelles probably accommodate the compartmentalizedsteps of the isoprenoid biosynthetic pathway leading to theproduction of isopentenyl pyrophosphate. As these ultrastructuralcharacteristics only exist in young gland cells of the currentseason's growth they seem to be the sole source of the precursorsfor both resin and rubber formation. Parthenium argentatum, guayule, resin canals, gland cells, plastids, smooth endoplasmic reticulum, rubber, resin, epithelial cells, ultrastructure