Using 2 Genetic Markers to Discriminate Among Canada Goose Populations in Ohio

Abstract: Canada goose (Branta canadensis) harvest management depends on reliable estimates of harvest composition, and established genetic methods provide an alternative to traditional methods. We expanded upon previous genetic studies by comparing the utility of 6 nuclear microsatellite loci and mitochondrial (mtDNA) control region sequences for discriminating among giant (B. c. maxima) and interior (B. c. interior) populations in Ohio (USA) Canada goose harvests at both individual and population levels. Subspecies and populations exhibited greater differentiation in mtDNA (F_ST = 0.202) than microsatellites (F_ST = 0.021), as would be expected based on differences in effective population size. Neither microsatellites nor mtDNA alone were sufficient for estimating harvest composition at the subspecies or population level in simulations and empirical blind tests using individuals of known origin; however, a combined microsatellite + mtDNA dataset yielded accurate and precise harvest derivations at the subspecies level. Both population-level mixed stock analysis and individual-level assignment tests provided accurate results, but a large proportion of birds could not be assigned with confidence at the individual level. We applied mixed stock analysis and the combined microsatellite + mtDNA dataset to Ohio's 2003–2004 harvest and found that interior populations accounted for 4.9% (95% CI = 1.7–8.0%) of the statewide early season and 9.3% (95% CI = 6.9–11.6%) of the regular and late-season harvested sample. These results suggest that maximum likelihood harvest derivations are highly dependent on the choice of genetic markers. Studies should only employ markers that exhibit sufficient variation and have been shown through simulations and empirical testing to accurately discriminate among the subspecies or management populations of interest.     

Effects of Natural Barriers and Habitat on the Western Spread of Raccoon Rabies in Alabama

Abstract: Although domestic animal transmission of rabies has largely been mitigated, the disease remains a concern in both Europe and North America where wildlife transmission has caused epizootics. Raccoon (Procyon lotor) rabies was established in Alabama, USA, in 1975, primarily in the southeastern corner of the state. However, with the exception of isolated events, rabies has not continued to spread westward across the Alabama River. We monitored movements of 100 radiocollared raccoons on 2 sites within hardwood and agriculture habitats in a rabies enzootic area east of the Alabama River, in managed pine habitat area west of the river where rabies sporadically occurs, and in a mixed pine hardwood area outside of the known rabies enzootic area to determine if raccoon movements and habitat use in certain habitat types and the presence of a river may serve as natural barriers preventing the western spread of rabies in Alabama. We also examined raccoon contact rates to determine if they influence disease transmission through static and dynamic interactions. Raccoons in mixed pine-hardwood forest habitats had smaller home ranges and less overlap of ranges compared to the other 3 habitats. However, static interactions between habitats in the use of overlap areas did not differ (F_11,129 = 1.63, P = 0.09). Rabies antibody titers were highest in the managed pine habitat (28%) even prior to oral vaccine bait distributions in spring of 2004 and 2005. Biomarker data from radiocollared and additional raccoons captured after the bait distribution west of the Alabama River demonstrated a low efficacy of the vaccine reaching the small southern raccoons. The combination of the river as a partial barrier, the high percentage of pine forested habitat west of the river, and limited spatial movements of raccoons within these forested habitats appears to have reduced the likelihood of rabies establishing west of the river. Understanding different host-habitat- disease systems is important for successful management of diseases. Based on our results, we recommend that the oral vaccine program continue to use the Alabama River as a partial barrier and baiting be concentrated in the fragmented bottomland hardwood forests and around larger bodies of water where raccoon densities are highest. Success of baiting strategies designed to take advantage of northern raccoon dynamics and habitat use may not be applicable to southern populations.     

Scanning Electron Microscopic Studies of Epicuticular Patterns in Mosquito Larvae (Diptera, Culicidae) and Their Use as Taxonomic Characters

The development of integumental patterns on the head capsule in larval instar I-IV of Aedes (Ochlerotatus) cantons (Meigen) was studied by SEM. A comparison of several areas on the head capsule was made. Polygonal patterns of small protuberances (vesicles) were found on the entire head capsule. Arrangements vary between different areas, but within each area they are constant from the II instar throughout larval development. A comparison with five other Aedes spp. in the IV instar shows species specificity of the vesicle patterns at two areas. There the arrangement varies between rhombic and irregular pentagonal shape with sizes from 28 to 42 μm, and from round knobs to more elongated ridges (each from 2.8 μm to 11.2 μm). Treatment with different fixatives was studied. A comparison between saddle and siphon patterns of the six species is made. The possible origin of the vesicles as well as their taxonomic significance is briefly discussed. Species specific patterns exist and improve the possibility of identifying closely similar larvae. Possibly the method when further developed may serve to distinguish species groups.     

The phylogenetic relationships among infraorders and superfamilies of Diptera based on morphological evidence

Members of the megadiverse insect order Diptera (flies) have successfully colonized all continents and nearly all habitats. There are more than 154 000 described fly species, representing 10–12% of animal species. Elucidating the phylogenetic relationships of such a large component of global biodiversity is challenging, but significant advances have been made in the last few decades. Since Hennig first discussed the monophyly of major groupings, Diptera has attracted much study, but most researchers have used non‐numerical qualitative methods to assess morphological data. More recently, quantitative phylogenetic methods have been used on both morphological and molecular data. All previous quantitative morphological studies addressed narrower phylogenetic problems, often below the suborder or infraorder level. Here we present the first numerical analysis of phylogenetic relationships of the entire order using a comprehensive morphological character matrix. We scored 371 external and internal morphological characters from larvae, pupae and adults for 42 species, representing all infraorders selected from 42 families. Almost all characters were obtained from previous studies but required revision for this ordinal‐level study, with homology assessed beyond their original formulation and across all infraorders. We found significant support for many major clades (including the Diptera, Culicomorpha, Bibionomorpha, Brachycera, Eremoneura, Cyclorrhapha, Schizophora, Calyptratae and Oestroidea) and we summarize the character evidence for these groups. We found low levels of support for relationships between the infraorders of lower Diptera, lower Brachycera and major lineages of lower Cyclorrhapha, and this is consistent with findings from molecular studies. These poorly supported areas of the tree may be due to periods of rapid radiation that left few synapomorphies in surviving lineages.     

Disappearance of gas vacuoles in the blue-green alga Microcystis aeruginosa

Abstract In a culture of Microcystis aeruginosa, which had been transferred from a mineral medium into distilled water, the number of gas vacuoles per cell decreased and reached a value of 20% of the control 24 h after transfer. In senescent cells grown on a mineral agar for several weeks, the gas vacuoles also disappeared. The disappearance of the gas vacuoles may be a response to a nutrient deficiency in both cultures.     

Herbivore feeding preferences in captive and wild populations

Investigations into the mechanisms underpinning plant selection by herbivores have often yielded conflicting results. Such inconsistency might stem from whether selection experiments are conducted with captive or wild populations, and upon the different measures of plant selection used to determine herbivore preference. Here we compared the feeding preferences of captive and wild kangaroos (Macropus fuliginosus) using a standard set of plant species (14 Hakea spp., Proteaceae) and several measures of herbivore selection to examine how environment influenced relative consumption. Three indices of herbivore consumption were measured: number of plants (NP), total shoot volume per plant (TV) and percentage available shoot volume (PV) consumed. NP and TV were closely correlated in the wild and captive populations and consistently correlated with six morphological and chemical plant attributes examined, the most notable being a strong negative correlation with shoot phenolic content. This uniformity suggests that plant selection by captive kangaroos is broadly consistent with that observed in field trials, and consequently that for macropods, at least, captive trials offer a valid way to determine the relative acceptability of different plant species. However, the fact that our third measure of herbivore selection PV was weakly correlated in captive and wild populations and showed no relationship with shoot phenolic content highlights the importance of which measure of plant selection is applied. We suggest that, while NP and TV are potentially confounded by plant size and availability, they offer the clearest insight into plant selection from the point of view of the herbivore, while PV is more suitable for plant‐centred studies.