Reducing Handling Time Research Articles

A comparison of plucked feathers versus blood samples as DNA sources for molecular sexing

Feathers are increasingly collected as a nondestructive source of DNA for avian genetic research. Although feather samples are not optimal in some important ways than more robust blood or tissue samples, feather sampling requires less training for field workers, results in shorter handling times for the organism, generates no hazardous wastes, and requires simpler storage procedures. Along with these largely positive attributes comes a set of challenges, particularly the relatively low copy number of DNA present in feather samples. We compared the utility and reliability of feathers to the more traditional blood samples as sources of DNA for polymerase chain reaction (PCR)-based molecular sexing of Black-capped Chickadees (Poecile atricapilla). DNA from 102 individuals was extracted separately from both single rectrices and from blood samples, and the sex of each bird was then determined using standard PCR-based methods. We found complete agreement between sex determinations based on feather versus blood DNA extractions. Slight variations in lab protocols were necessary to obtain consistent results from these two DNA sources; and we briefly discuss other sources of error that could occur in feather-based molecular sexing studies. This controlled comparison of feather versus blood samples demonstrates that plucked rectrices provide a highly reliable source of DNA for molecular sexing of wild birds. SINOPSIS Se esta incrementando la modalidad de usar plumas como una fuente no destructiva de ADN para llevar a cabo investigacion genetica en aves. Aunque las muestras tomadas de plumas, en algunas instancias no son optimas que muestras mas robustas como sangre y tejido, el uso de estas no requiere adiestramiento especial, toman menos tiempo en la manipulacion del ave, no generan desperdicios peligrosos y requieren un almacenaje sencillo. Aunque hay atributos positivos en el uso de plumas, tambien existe el problema de obtener una muestra baja de ADN. Examinamos la utilidad y confiabilidad de muestras de plumas en comparacion con tecnicas mas tradicionales como obtencion de muestras de sangre como una fuente de ADN para el sexado de Poecile atricapilla utilizando PCR. A tales efectos se extrajo ADN, de rectrices, de 102 individuos y un numero similar de muestras de sangre para determinar el sexo usando PCR. Encontramos resultados similares con ambos metodos. Sin embargo, fueron necesarios pequenas variaciones en el protocolo de laboratorio para obtener resultados consistentes, de ambas fuentes de ADN. Discutimos algunas fuentes de error que pueden ocurrir cuando se utilizan plumas para la determinacion del sexo utilizando tecnicas moleculares. Este estudio demuestra que las rectrices son una fuente confiable para obtener buenas muestras de ADN y poder determinar el sexo en aves silvestres.

Effect of Experience on Prey Species Selection by the Bivalve Feeder Halla Okudai (Polychaeta: Lysaretidae)

We report on the effects of previous foraging experience on prey-selection by the bivalve feeding polychaete Halla okudai, including whether there was evidence of frequency-dependent predation. Three separate batches of H. okudai were maintained for 30 days on clams, mussels, or oysters, before being offered a choice among these three prey. Initially individuals from all three treatments consumed more clams than mussels, and no oysters. As the number of clams was depleted the polychaetes shifted their diet to include a greater proportion of mussels, but even after 20 days oysters were only eaten by polychaetes that had been previously acclimated to them. Nevertheless, polychaetes from each treatment inspected significantly more of the prey species to which they had initially been acclimated, suggesting that previous experience may increase the likelihood of certain prey being detected. When individuals of H. okudai were repeatedly offered the same prey species, handling time did not decrease (and therefore prey profitability did not increase) with experience, which may be because H. okudai paralyses its prey with toxic mucus. Since repeated experience of the same prey species gives no advantage in terms of reduced handling time, we suggest this may be why this species does not show frequency-dependent prey-selection.

TRADEOFFS BETWEEN PREDATION RISK AND FEEDING IN A LIZARD, THE BROAD-HEADED SKINK (EUMECES LATICEPS)

AbstractForaging, feeding, and escape decisions may all be modified by threat of predation. Field experiments using a human simulated predator show that a lizard, the broad - headed skink, Eumeces laticeps, alters several aspects of feeding behavior in ways suggesting tradeoffs between predation risk and feeding. When food (cricket) was closer to the predator, the lizards more frequently did not attack it, and often retreated to safety before consuming it, reducing the duration of exposure to predation. The probability of attacking a cricket decreased with distance of the lizard from refuge, reflecting greater risk due to increased time required to reach refuge. Latency to attack increased with distance of the lizard from refuge, suggesting that lizards assessed the risk as acceptable after observing the predator's continued immobility. Large crickets were attacked with higher probability and shorter latency than small crickets, indicating that greater risk was acceptable for greater energetic benefit. The lizards more frequently carried large than small crickets to refuges before eating them, reducing duration of exposure because handling time was greater for larger crickets. Smaller crickets were consumed where captured, again indicating modification of feeding behavior in response to predation risk. The skinks also reduced risk by reducing handling time when closer to the predator. Escape was delayed until a predator approached closer when lizards were eating than when not eating. This delay may reflect a tradeoff between predation risk and acquisition of food.

Direct sowing of Coffea arabica somatic embryos mass-produced in a bioreactor and regeneration of plants.

The effect of germination conditions on the morphology of Coffea arabica L. somatic embryos mass-produced in a 1-l temporary immersion bioreactor (RITA®) was studied with emphasis on direct sowing in soil. Using germinated embryos, direct sowing resulted in a highly successful conversion of embryos into plants. A culture density above 1600 embryos per 1-l bioreactor positively affected embryo morphology by causing higher embryonic axis elongation (+4-5 mm). At this density, the addition of a high concentration of sucrose (234 mM) 2 weeks before sowing promoted an increase in effective plant conversion in soil (78%) and a vigorous vegetative growth of the resulting plants. Furthermore, direct sowing reduced handling time to 13% and shelving area requirements to 6.3% of the values obtained by conventional acclimatization of plants developed on gel media.

Effect of experience on predatory behaviour of dogwhelks

We used an acoustic transducer to monitor the radular activity of dogwhelks, Nucella lapillus , drilling mussels, Mytilus edulis , in the laboratory and we examined the effect of dietary experience on prey-handling behaviour. For the first time, phases of inspection, penetration and ingestion could be distinguished directly, and consequently the prey-handling process analysed in detail. Dogwhelks with different field-based experience of mussels showed different handling behaviour. Those collected from a mussel-dominated shore more readily adopted the faster method of penetrating between the slightly gaping valves, instead of the slower method of drilling through the shell. Those collected from a barnacle-dominated shore took significantly longer to attack the mussel and then were unable to switch from drilling to penetrating through the gape between valves. Experience of specific prey in the field, by reducing handling time, could promote fitness by reducing exposure to environmental hazards. Laboratory attempts to train dogwhelks from the barnacle-dominated shore to use the gape penetration method failed, suggesting that functional constraints, such as injection of a relaxant when penetrating through the gape and/or genetically controlled behavioural traits, could limit the ability to learn handling skills.

An Antibiotic Rodenticide for Pine Voles in Orchards

mals usually require collars with a large expansion ratio, but care must be taken to ensure that the pendant does not hit the knees and thereby hinder leg movement. The placement of the stop ring is critical to limit pendant drop. Excessively stiff, hard-to-stretch elastic should be avoided. A 1.5 expansion ratio (e.g., 30cm length stretched to 45 cm with a 454g weight) is about right. Swivel snaps like those used for attaching reins to livestock halters make ideal slip rings. They open easily for encircling the steel cable, thus allowing opened collars to be fitted around the neck. This fast and easy attachment eliminated some of the trauma for the wild animals by reducing handling time.