Life stage specific variation in the occupancy of ponds by Litoria aurea,a threatened amphibian

Breeding aggregations are a reproductive strategy to increase mate finding opportunity. However, because aggregations skew the distribution of mature animals through conspecific attraction, rather than resource availability, the distribution of breeding sites may be reduced, so that not all suitable breeding sites are used. To examine the relationship between landscape and reproductive strategies of a threatened frog, Litoria aurea, we studied its distribution at Sydney Olympic Park over two breeding seasons. We aimed to: (i) determine the distribution and predictors of breeding ponds; and (ii) assess the significance of dispersal in the juvenile age‐class. We found that the distribution of the calling males was highly skewed and occurred in large, well‐connected ponds. Despite this, breeding ponds were not aggregated; pond size was the single factor explaining the distribution of breeding ponds. Juvenile frogs dispersed from breeding ponds and were not associated with a specific pond characteristic. Less breeding occurred in the second season during which fewer ponds were used for breeding including many different ponds from the previous year. These changes suggest that breeding effort and breeding pond choice are dynamic and therefore knowledge of the factors that drive breeding events will be a powerful tool in managing species, particularly in light of changing climatic regimes.     

The Use of C14-Proline by Growing Cell: Its Conversion to Protein and Hydroxyproline

C¹⁴-proline is readily absorbed by growing tissue cultures ofcarrot root phloem and of potato tuber in experiments carriedout under aseptic conditions. The C¹⁴-proline rapidly entersinto the protein of the tissue, appearing there in as shorta period as 15 minutes, and, thereafter, the amount incorporatedinto the protein bears a linear relation to time. Virtuallyall the C¹⁴ appears in the protein hydrolysate in the form ofproline and hydroxyproline. It is shown that the conversionfrom proline to hydroxyproline occurs after the C¹⁴-prolineis combined into the protein and that this conversion proceedsprogressively with time. The ratio of C¹⁴ as proline to C¹⁴as hydroxyproline declined progressively from a value of 4.0after 30 minutes of contact and seemed to become stabilizedeventually at 0.7. C¹⁴-hydroxyproline, which can be absorbedby the tissue, seems not to be incorporated into the proteinas such. The protein moiety which contains the C¹⁴-hydroxyprolinefrom C¹⁴-proline represents a stable protein which is not metabolizedand whose carbon does not ‘turn over’. This inertprotein seems to be characteristic of cells which are in rapiddivision under the influence of coconut milk or are synthesizingprotein in response to other stimuli such as the events at acut tissue surface. The protein in question seems to be presentmainly in the cytoplasm rather than in its paniculate inclusions.These results are compatible with earlier views which requirethat part of the protein in the cell ‘turns over’its carbon, whereas another part does not do so.     

The inactivation of bacteriophage by ionizing radiation

The loss of energy by a fast, charged particle in dry material of atomic constitution approximating a protein is described and the important features tabulated. The inactivation of T-1, T-3, and T-7 bacteriophages in the dry state by deuterons is described and follows a simple logarithmic survival curve. The cross section per deuteron is much less than the electron microscope cross section in all three cases and indicates some kind of structure to the viruses. The variation of cross section with ionization density has been measured for T-1. It is linear and the kind of internal-structure which could account for this is discussed.     

The extinction and foundation of local butterfly populations in relation to population variability and other factors

Abstract.

• 1 Definitions were adopted for the identification of the extinction and foundation of populations in data from the Butterfly Monitoring Scheme from 1976 to 1991. The data are indexes of abundance, not population estimates.
• 2 The frequency of extinctions and foundations for twenty-eight butterfly species was assessed in relation to characteristics of their population fluctuations, as indicated by fluctuations in the index values.
• 3 Using multiple regression, the best predictive equation for the number of extinctions plus foundations included the number of test data available, the mean index per site and the first serial correlation. Two measures of variability were included in the analysis, but were not retained in the best predictive equation.
• 4 Some results for individual species are described and the potential of the approach for the study of effects of climatic warming is emphasized.