Direct Estimation of Early Survival and Movements in Eastern Wolf Pups

Abstract: Determining juvenile survival and recruitment rates is essential to assess status and viability of animal populations. Currently, the demographic attributes of juvenile carnivores, specifically wolves (Canis lycaon), are poorly known but of considerable conservation interest. We measured survival and dispersal rates for 51 juvenile (age 3.5–31 weeks) wolves in Algonquin Provincial Park, Canada, from 2004 to 2005, using implantable very high frequency transmitters. Monthly pup survival was high (0.970, 95% CI = 0.951–0.990) and constant from June to November, and most pup mortality was from natural causes. Pups dispersed as early as age 15 weeks, and monthly dispersal rates were high for young pups (min. = 0.008, 95% CI = 0.000–0.019; max. = 0.030, 95% CI = 0.010–0.050). We failed to detect any influence of pack or litter size on pup survival or probability of dispersal. Radiotelemetry offers an individual-based monitoring technique capable of providing direct assessment of wolf pup survival and movements, with rigorous estimation of survival and dispersal rates and quantification of cause-specific mortality.     

Embryonic control of isocitrate lyase activity in the megagametophyte of ponderosa pine seeds

The intensity of the process of redistribution of the elements potassium, boron, iron, magnesium and calcium was determined by following the rate of accumulation of these elements into the fruits of apple (Malus domestica Borkh.) trees. The determination is based on the assumption that the process of primary distribution via the xylem becomes relatively unimportant with respect to supply along the phloem during the period of fruit growth. Thus a decreasing rate of accumulation for a phloem-immobile and xylem-mobile element will be seen during this period of growth, while an element which is mobile in both pathways will give a linear rate of accumulation when the supply by the root does not alter too much. In addition, the ratios of the contents in fruits and leaves were used as an indicator of the relative mobility in redistribution. In these experiments with apple, potassium and boron showed a high mobility. Magnesium and especially calcium showed a much lower mobility in redistribution than in the primary rate of supply. Iron was intermediary. The results, especially for boron and magnesium, are in contradiction to some of the data in the literature. Further studies are needed before these contrasting results can be explained.     

The naturalization to invasion transition: Are there introduction‐history correlates of invasiveness in exotic plants of Australia?

Of the large number of exotic plant species that become naturalized in new geographic regions, only a subset make the transition to become invasive. Identifying the factors that underpin the transition from naturalization to invasion is important for our understanding of biological invasions. To determine introduction‐history correlates of invasiveness among naturalized plant species of Australia, we compared geographic origin, reason for introduction, minimum residence time and growth form between naturalized non‐invasive species and naturalized invasive plant species. We found that more invasive species than expected originated from South America and North America, while fewer invasive species than expected originated from Europe and Australasia. There was no significant difference between invasive and non‐invasive species with respect to reason for introduction to Australia. However, invasive species were significantly more likely to have been resident in Australia for a longer period of time than non‐invasive species. Residence times of invasive species were consistently and significantly higher than residence times of non‐invasive species even when each continent of origin was considered separately. Furthermore, residence times for both invasive and non‐invasive species varied significantly as a function of continent of origin, with species from South America having been introduced to Australia more recently on average than species from Europe, Australasia and North America. We also found that fewer invasive species than expected were herbs and more invasive species than expected were primarily climbers. Considered together, our results indicate a high propensity for invasiveness in Australia among exotic plant species from South America, given that they appear in general capable of more rapid shifts to invasiveness than aliens from other regions. Furthermore, our findings support an emerging global generality that introduction‐history traits must be statistically controlled for in comparative studies exploring life‐history and ecological correlates of invasion success.     

Intergeneric hybrids between Crataegus L. and Mespilus L.: a fresh look at an old problem

A brief outline is given of the history and nomenclature of the sexual and graft hybrids (chimeras) between Crataegus and Mespilus. An investigation has been made of some aspects of the macromorphology, the pollen fertility and exine characters, cytology and physiology of the plants growing in the Royal Botanic Gardens, Kew. It is suggested that in the past too much emphasis has been laid on the anatomy of the epidermal layers and the separation of parental characters in chimeras. Observations made during the study show the presence of intermediate characters in the graft hybrid as well as in the sexual hybrid and there is evidence that most parts of the graft hybrids are probably influenced by both the parental genotypes.     

Herbicide Tolerance and Polyploidy in Cynodon dactylon (L.) Pers. (Gramineae)

Responses to treatment with the herbicide dalapon have beendetermined and the karyotypes studied in four chromosome racesof Cynodon dactylon. No relationship was found between toleranceto dalapon and the level of ploidy. At the dalapon concentrationwhere differences in response were most apparent (2·5mM), the difference in mean value of the two diploid cloneswas greater than any other pair of values. No positive correlationwas found between tolerance and the morphology of the leaf surface.Karyotype studies have not resolved the conflicting evidencerelating to the origin and inter-relationships of the chromosomeraces of this species.