Factors Affecting the Transmission of Rodent Ultrasounds in Natural Environments

Recent evidence indicates that myomorph rodent species use ultrasoniccalls as communication signals. The range over which sound communicationsignals may travel and the ease with which they may be localizeddepends on their intensity and structure and the structure ismade. It is concluded that rodent calls are mainly within therange 20–100 kHz and not longer than 300 msec, exceptfor some rat calls which last up to 3 sec. Intensities may beas high as 103 dB SPL (at 10 cm) in pups and 86 dB SPL (at 5–30cm) in adults. Bandwidths between 1–104 kHz are found.High frequency sounds are attenuated with distance more thanlower frequency sounds, mainly by atmospheric attenuation, groundattenuation and scattering. These effects are not all linearso it is difficult to predict how far rodent sounds may travelwithout making measurements under the conditions in which soundsare known to be produced by rodents in the wild. It is shownthat there is little attenuation due to scattering from vegetationin a wood inhabited by woodmice. But in grass or wheat wherefield voles may live, sounds above 20 kHz are rapidly attenuated.Attenuation may be much less in rodent runs and burrows andthis is being studied by a new spark technique.     

The Germination of Carrot (Daucus carota L.) Seed Harvested on Two Dates: A Physiological and Biochemical Study

The germination of two batches of carrot seed, harvested 44and 104 d after anthesis, was compared at 10 °C. Proteinand nucleic acid contents of the seeds were measured at intervals,together with fresh weight and respiration rate. The matureseed germinated 3.7 d earlier than the immature seed, with nodifference in percentage germination. The dry mature seed containedmore protein and nucleic acid per unit dry matter than did theimmature seed, and proportions of nucleic acid present as rRNAand poly(A)RNA were greater in the mature seed. The sequenceof metabolic reactivation was the same in both batches of seed,as were the relative rates of increase of each nucleic acidcomponent, fresh weight, and respiration rate. Differences inthe composition of the dry seed appear to be responsible forthe observed difference in rate of germination between the twoseed batches.     

Natural selection and the distribution of shell colour morphs in three species of Littoraria (Gastropoda: Littorinidae) in Moreton Bay, Queensland

The distribution of yellow, brown and red morphs of sympatric species of Littoraria were recorded on mangrove trees of the genus Avicennia within Moreton Bay, Queensland. The roles of background mimicry (leaf vs. bark, dark vs. light), niche selection and thermal tolerance (sunny vs. shaded positions and height above ground) were examined. The yellow advantage found previously in the area was tested. Total yellow morph frequency adjusted to a reduction in leaf background on pruned trees. Morph frequencies in Littoraria species reflect differences in habitat use. L. filosa (high yellow frequency) was more frequently found on leaves at the highest tree levels, while L. luteola (high brown frequency) was more frequently found on branches at lower levels. It is therefore argued that morphs mimic background elements. Previously reported niche selection by yellow and brown morphs of leaf and bark backgrounds is shown to be a result of the distribution of L. luteola on branches and L. filosa on leaves. At warmer times of the year, yellow L. filosa were more common in sunny positions; this is thought to be a result of thermal tolerance. There appears to be some advantage to particular morphs on particular tree types, but this relationship needs to be examined further. Mangrove-dwelling Littoraria are a promising model to investigate molluscan polymorphism. In the past, erroneous identification of sympatric species may have influenced the accuracy of reported patterns. We used allozyme electrophoretic markers as a precise identification technique. © 2002 The Linnean Society of London, Biological Journal of the Linnean Society , 2002, 75 , 219–232.     

Glucosinolates in oilseed rape (Brassica napus) and the incidence of pollen beetles (Meligethes aeneus)

During an early stage of migration into a field of oilseed rape in the spring of 1988, more pollen beetles were observed on the double-low variety, Ariana, than on the adjacent single-low varieties, Bienvenu and Mikado. More beetles were found on open flowers on terminal racemes than on yellow and green flower buds on lateral racemes. Five alkenyl, three indolyl and two aromatic glucosinolates were identified in the floral tissues of oilseed rape. The major compounds were progoitrin (2-OH, 3-butenyl) and glucobrassicanapin (4-pentenyl). There were no differences in the types and concentrations of glucosinolates present in the terminal and lateral racemes of any variety, and only small differences between single- and double-low varieties. Concentrations of glucosinolates in floral tissues of crops grown with a little nitrogen were twice those of well-fertilised crops. There was no association between the number and distribution of pollen beetles on plants and the amounts or types of glucosinolates present in floral tissues.     

Phenotypic plasticity and geographical variation in the pre-reproductive period of Autographa gamma (Lepidoptera: Noctuidae) and its implications for migration in this species

Abstract.

• 1 Adults of the noctuid moth Autographa gamma undertake seasonal migrations into areas where they are unable to breed continuously. Individuals migrate into Britain each spring, and offspring of these migrants probably return in autumn to over-wintering areas in North Africa and the Middle East. However, the existence of these return migrations has been questioned.
• 2 Insects usually migrate during the adults' pre-reproductive period (PRP). The length of this period is therefore an index of migratory potential since individuals with longer PRPs have more time to express their potential for flight and to travel further before becoming sexually mature.
• 3 Offspring of insects from Morocco, Britain and Germany showed that, under both long and short photoperiods, PRP increased with latitude over the range 34–53°N. There were significant genotype—environment interactions in the effect of photoperiod on length of PRP.
• 4 However, PRPs of offspring from insects collected in Sweden were no different under a long photoperiod from those of offspring collected further south, and were significantly shorter under a short photoperiod than those of insects from Morocco.
• 5 With the exception of Swedish moths, offspring from insects collected at higher latitudes had longer PRPs and, therefore, the potential to travel further during migrations. The ability of some individuals to respond to environmental cues signalling habitat deterioration will further increase their potential to return to over-wintering areas further south.

     

RESPONSE SURFACES OF SENSORY CHARACTERISTICS FOR REDUCED SODIUM CHLORIDE AND PHOSPHATE SALTS IN EMULSIFIED TURKEY SAUSAGES

Emulsified turkey sausages (ETS) were prepared using varying concentrations of sodium chloride (NaCl; 1.5 to 2.0%), sodium tripolyphosphate (STPP, 0 to 0.5%), and sodium acid pyrophosphate (SAPP, 0 to 0.25%). The sensory characteristics (response variables) of saltiness, soapiness, and texture were evaluated using a trained taste panel. Response surface methodology was used to design and analyze this study. Over the levels of STPP and SAPP, saltiness increased as levels of NaCl were increased. When STPP and SAPP were evaluated in combination with NaCl, saltiness increased slightly as levels of STPP were increased; and saltiness decreased as levels of SAPP were decreased. Soapiness increased at low levels of NaCl (1.5%) as STPP increased. Texture firmness decreased as SAPP increased and STPP decreased at low levels of NaCl (1.5%). Results suggest that sensory perceptions in ETS products are a combination of NaCl, SAPP, and STPP mixtures.     

Partition of 14C Assimilate between Organs and Fractions of Contrasting Varieties of Carrot during Initiation of the Storage Root

This work examines the differences in partition and activityof ¹⁴C in two varieties of carrot (Daucus carota L.) contrastingin shoot to storage root ratio at maturity. Plants were grownin a controlled environment of 20 ?C and 500 µmol m^–2s^–1. During initiation of the storage root (10–25d from sowing) plants were exposed to ¹⁴CO₂ for 1 h and theradioactivity in ethanol-soluble and -insoluble fractions ofshoots, storage and fibrous roots estimated at various timesup to 48 h after exposure. Between 35% and 40% of radioactivityinitially present in the plants was respired during the first24 h and 25–35% of that remaining after 24 h was foundin the roots, depending on age. The proportion found in thestorage region remained fairly constant between 15 and 25 dand was smaller than at 10 d. In the variety with a larger proportionof storage root at maturity (cv. Super Sprite), there was agreater proportion of label in both ethanol-soluble and -insolublefractions of the storage region soon after storage root initiationhad begun than in the variety with a smaller proportion of storageroot at maturity (cv. Kingston). There was no varietal differencein specific activities of the storage roots, but fibrous rootsof cv. Super Sprite showed a greater specific activity thanin cv. Kingston. Differences in shoot to storage root ratiomay thus be associated with characteristics of the fibrous roots.Partition and specific activities are discussed in relationto the initiation and development of the storage organ. Key words: Daucus carota, carrot, assimilate, partition, ¹⁴C, storage root     

Is Moyeria a euglenoid?

Moyeria , with a known age span of Middle Ordovician through Silurian, and normally placed in the acritarchs, may have euglenoid affinities. If this conclusion is correct it represents the oldest freshwater protozoan, because Moyeria is abundant in fluvial beds in Pennsylvania and New York, as well as in nearshore marine beds at many localities elsewhere. Paramecium is the only other typically freshwater protozoan with a pre-Cenozoic fossil record (a single, unillustrated Cretaceous report): euglenoids have rare Cenozoic records. As a freshwater taxon, or one capable of living in freshwaters, Moyeria , regardless of taxonomic assignment, provides further evidence about the early complexity of the freshwater ecosystem. □ Euglenoids, freshwater, Ordovician, Silurian, protozoans, acritarchs.