Testing alternative models for the conservation of koalas in fragmented rural–urban landscapes

Abstract Predicting the various responses of different species to changes in landscape structure is a formidable challenge to landscape ecology. Based on expert knowledge and landscape ecological theory, we develop five competing a priori models for predicting the presence/absence of the Koala (Phascolarctos cinereus) in Noosa Shire, south‐east Queensland (Australia). A priori predictions were nested within three levels of ecological organization: in situ (site level) habitat (<1 ha), patch level (100 ha) and landscape level (100–1000 ha). To test the models, Koala surveys and habitat surveys (n = 245) were conducted across the habitat mosaic. After taking into account tree species preferences, the patch and landscape context, and the neighbourhood effect of adjacent present sites, we applied logistic regression and hierarchical partitioning analyses to rank the alternative models and the explanatory variables. The strongest support was for a multilevel model, with Koala presence best predicted by the proportion of the landscape occupied by high quality habitat, the neighbourhood effect, the mean nearest neighbour distance between forest patches, the density of forest patches and the density of sealed roads. When tested against independent data (n = 105) using a receiver operator characteristic curve, the multilevel model performed moderately well. The study is consistent with recent assertions that habitat loss is the major driver of population decline, however, landscape configuration and roads have an important effect that needs to be incorporated into Koala conservation strategies.     

Promoting Effect of Fusicoccin on Seed Germination

The effects of fusicoccin on the germination of dormant, light-requiring or abscisic acid-inhibited seeds has been investigated. (1) Fusicoccin (10^?6M) induces germination in dormant wheat seeds (Triticum durum cv. Cappelli; 1972 crop) and stimulates it in seeds already relieved from dormancy (1971 crop), with an effect similar to that of gibberellic acid. (2) Fusicoccin (1.5 × 10^?6M) is more active than the two phytohormones gibberellic acid and benzyladenine and than white light in stimulating light-requiring lettuce seeds (Lactuca sativa cv. Grand Rapids) to germinate. Germination of radish seeds (Raphanus sativus) is also accelerated by fusicoccin, while benzyladenine and gibberellic acid are less active in this material. (3) Fusicoccin (1.5 × 10^?5M) removes almost completely the inhibitory effect of abscisic acid on germination of radish and lettuce seeds, whereas benzyladenine (10^?4M) and gibberellic acid (3 × 10^?4M) remove the inhibition only partially. The possible relationship between these results and previous information on growth by cell enlargement is discussed in terms of the mechanism of action of fusicoccin as compared with natural hormones.     

HISTOPATHOLOGICAL AND HISTOCHEMICAL CHANGES IN HONEYBEE LARVAE (APIS MELLIFERA L.) AFTER INFECTION WITH BACILLUS LARVAE,THE CAUSATIVE AGENT OF AMERICAN FOULBROOD DISEASE

Morphological, histochemical and cytochemical changes were examined in honeybee larvae after infection with the bacterium Bacillus larvae. The results indicate cell necrosis in the midgut epithelium accompanied by increasing cell vacuolization and nuclear pyknosis following per os inoculation with B. larvae. Many autolysosomes were positive for acid phosphatase. Non-vacuolar acid phosphatase activity was also found in lysed cell compartments. No such activity was found in regenerative epithelial cells. Degradation of haemocytes, salivary glands and other tissues was also observed. Histochemical analyses after per cutaneous inoculation with B. larvae of three- and five-day-old honeybee larvae show intense non-vacuolar acid phosphatase activity followed by disintegration of infected salivary glands, epithelial cell cytoplasm and haemocytes.     

Leaf Ecology of Pre-reproductive Ontogenetic Stages of the Palm TreeEuterpe edulisMart. (Arecaceae)

We studied leaves of 208 seedlings (S), infants (I) and juveniles(J) ofEuterpe edulis,randomly selected from plants in 1 ha ofswampy forest in SE Brazil. Each new leaf began extending afterthe complete development of the preceding leaf. The sequencesteps of leaf growth were emergence, linear growth while closed,opening of segments and logarithmic growth of the petiole. Averageleaf production rate (2.21 leaves per plant year^-1) did notvary among ontogenetic stages, conforming to a plastochronicrhythm. Average linear growth rate of the closed leaf was directlyrelated to average area of the open lamina. Herbivores attacked33.0% of all leaves giving rise to up to 10% loss of area andincluded damping-off-inducing suckers (7.1%), ordinary suckers(9.8%), chewers (5.4%), miners (2.7%) and multiple attacks (8.0%).These attacks varied among stages (S=22.4%, I=38.1%, J=33.3%),as did leaf mortality rates (S=26.5%, I=14.3% and J=0.0%). Unknownfactors were the main cause of leaf mortality (S=14.3%, I=7.1%).Not losing a leaf while a seedling and attaining a minimum leafarea in the infant stage were critical events for survival.Plants gained leaf area by not losing leaves while a seedling,by producing larger leaves with greater growth rates, and byaccumulating leaves with longer lifespans. The petiole can simulatean energetically cheaper branch, delimit a vital space aroundthe stem, favourably position the leaf lamina and substituteprovisionally for stem growth in height.Copyright 1999 Annalsof Botany Company Arecaceae,Euterpe edulis, herbivory, leaf ecology, leaf growth, leaf production, semideciduous forest, southeastern Brazil.     

Genetic diversity and evolutionary history of the Tyrrhenian treefrog Hyla sarda (Anura: Hylidae): adding pieces to the puzzle of Corsica–Sardinia biota

The Corsica–Sardinia archipelago is a hotspot of Mediterranean biodiversity. Although tempo and mode of arrival of species to this archipelago and phylogenetic relationships with continental species have been investigated in many taxa, very little is known about the current genetic structure and evolutionary history subsequent to arrival. In the present study, we investigated genetic variation within and among populations of the Tyrrhenian treefrog Hyla sarda, a species endemic to the Corsica–Sardinia microplate and the surrounding islands, by means of allozyme electrophoresis. Low genetic divergence (mean D_nei = 0.01) and no appreciable differences in the levels and distribution of genetic variability (H_E: 0.06–0.09) were observed among all but one populations (Elba). Historical demographic and isolation‐by‐distance analyses indicated that this diffused genetic homogeneity could be the result of recent demographic expansion. Along with paleoenvironmental data, such expansion could have occurred during the last glacial phase, when wide and persistent land bridges connected the main islands and a widening of lowland areas occurred. This scenario is unprecedented among Corsica–Sardinia species. Together with the lack of concordance even among the few previously studied species, this suggests either that species had largely independent responses to paleoenvironmental changes, or that most of the history of assembly of the Corsica–Sardinia biota is yet to be written. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 103 , 159–167.     

Testing models of female reproductive migratory behaviour and population structure in the Caribbean hawksbill turtle, Eretmochelys imbricata, with mtDNA sequences

Information on the reproductive behaviour and population structure of female hawksbill turtles, Eretmochelys imbricata , is necessary to define conservation priorities for this highly endangered species. Two hypotheses to explain female nest site choice, natal homing and social facilitation, were tested by analyzing mtDNA control region sequences of 103 individuals from seven nesting colonies in the Caribbean and western Atlantic. Under the social facilitation model, newly mature females follow older females to a nesting location, and subsequently use this site for future nesting. This model generates an expectation that female lineages will be homogenized among regional nesting colonies. Contrary to expectations of the social facilitation model, mtDNA lineages were highly structured among western Atlantic nesting colonies. These analyses identified at least 6 female breeding stocks in the Caribbean and western Atlantic and support a natal homing model for recruitment of breeding females. Reproductive populations are effectively isolated over ecological time scales, and recovery plans for this species should include protection at the level of individual nesting colonies.