Ability of predatory native Australian fishes to learn to avoid toxic larvae of the introduced toad Bufo marinus

Of two native Australian fishes naïve to the introduced toad Bufo marinus most barramundi Lates calcarifer rapidly learned to avoid B. marinus tadpoles, while sooty grunter Hephaestus fuliginosus exhibited considerable intraspecific variation in their learning ability. Some sooty grunter learned to avoid tadpoles after only a few attacks, while other individuals continued to attack and reject tadpoles throughout the entire laboratory trials. Individuals of both species recognized and avoided tadpoles 1 day after their previous encounter. None of the fishes died during the trials. The observed variation in behavioural responses of fishes to B. marinus may be due to differences in (1) learning ability, (2) fish hunger levels, and or (3) tadpole palatability and toxicity. The results demonstrate that most barramundi and sooty grunter learn to avoid B. marinus tadpoles with minimal trauma. Consequently, it is anticipated that the toads are unlikely to have a significant negative impact on wild populations of these fishes through direct toxic effects.     

The fifteenth- and twentieth-century colonization of the Basin of Mexico by the Great-tailed Grackle (Quiscalus mexicanus)

Historical evidence indicates that Great‐tailed Grackles colonized the Basin of Mexico from the Gulf Coast lowlands in the fifteenth century. They were probably assisted by an intentional introduction, but colonization succeeded because of anthropogenic habitat alterations over the previous two centuries. During the Colonial period, grackles withdrew from the Basin, only to recolonize it in recent decades. This withdrawal was also due probably to changes in land use, including drainage of much of the water from the Basin's lakes.     

Where ichthyofaunal provinces meet: the fish fauna of the Lake Edward system,East Africa

Based on literature, museum collections and three recent expeditions, an annotated species list of the Lake Edward, East Africa, drainage system is presented, excluding the endemic haplochromines. A total of 34 non-Haplochromis species belonging to 10 families and 21 genera are recorded from the system. Three of these are endemic and two others have been introduced in the region. Six species are new records for the Lake Edward system. A species accumulation curve indicates that we probably covered most of the non-Haplochromis species in the area sampled during the recent expeditions, but undetected species might still be present in the Congolese part of the system, which is poorly sampled. A comparison of the species list with those of neighbouring basins confirmed the placement of the Lake Edward system within the east-coast ichthyofaunal province.     

Morphological dispersion of introduced Hawaiian finches: evidence for competition and a Narcissus effect

Summary Morphological analyses were conducted on finch species introduced to Oahu, Hawaii. As many as 25 species of finches representing four families (Emberizidae, Fringillidae, Ploecidae, Estrildidae) have been introduced to Oahu. Of these, 15 species currently have established wild populations. When compared with pools of 25 and 23 species introduced to Oahu, the 15 surviving species are morphologically overdispersed. This result is consistent with the hypothesis that competition has influenced the outcome of these introductions. We also tested the hypothesis that surviving introduced finches in one habitat (sugarcane fields) were morphologically overdispersed. When the seven surviving finch species found in sugarcane were compared with the pools of 25 and 23 species, they too were morphologically overdispersed. However, when the seven sugarcane species were compared with a species pool consisting of only the surviving 15 species found across Oahu, they were not morphologically overdispersed. This result suggests that morphological analyses of community structure based only on comparisons of assemblages of surviving species may be biased by a Narcissus effect.     

Survival of Pseudomonas fluorescens and Bacillus subtilis introduced into two soils of different texture in field microplots

Abstract Antibiotic-resistant strains of Pseudomonas fluorescens and Bacillus subtilis , produced by transposon Tn5 mutagenesis and transformation with plasmid pFT30, respectively, were characterized. Both strains grew at a rate comparable to that of the wild-type strains, and the antibiotic resistance remained stable for over 50 generations without selective pressure. During the growing season, the survival of these strains was studied in two soils of different texture cropped with wheat. The B. subtilis populations declined rapidly in both soils and then stabilized at the levels of added spores. P. fluorescens showed a slow, steady decline in both soils; survival was better in the finer-textured soil, a silt loam, than in the coarser loamy sand. For both bacteria, some translocation to deeper soil layers was observed. No significant rhizosphere effects were detected in either of the two soils.     

THE GENUS PIKEA (DUMONTIACEAE,RHODOPHYTA) IN ENGLAND AND THE NORTH PACIFIC: COMPARATIVE MORPHOLOGICAL,LIFE HISTORY,AND MOLECULAR STUDIES1

A Pikea species attributed to Pikea californica Harvey has been established in England since at least 1967. Previously, this species was believed to occur only in Japan and Pacific North America. Comparative morphological studies on field-collected material and cultured isolates from England, California, and Japan and analysis of organellar DNA restriction fragment length polymorphisms, detected using labeled organellar DNA as a non-radioactive probe, showed that English Pikea is conspecific with P. californica from California. Both populations consist of dioecious gametophytes with heteromorphic life histories involving crustose tetrasporophytes; 96% of organellar DNA bands were shared between interoceanic samples. A second dioecious species of Pikea, P. pinnata Setchell in Collins, Holden et Setchell, grows sympatrically with P. californica near San Francisco but can be distinguished by softer texture, more regular branching pattern, and elongate cystocarpic axes. Pikea pinnata and P. californica samples shared 49–50% of organellar DNA bands, consistent with their being distinct species. Herbarium specimens of P. robusta Abbott resemble P. pinnata in some morphological features but axes are much wider; P. robusta may represent a further, strictly sub-tidal species but fertile material is unknown. Pikea thalli from Japan, previously attributed to P. californica and described here as Pikea yoshizakii sp. nov., are monoecious and show a strikingly different type of life history. After fertilization, gonimoblast filaments grow outward through the cortex and form tetrasporangial nemathecia; released tetraspores develop directly into erect thalli. Tetrasporoblastic life histories are characteristic of certain members of the Phyllophoraceae but were previously unknown in the Dumontiaceae. Japanese P. yoshizakii shared 55 and 56% of organellar DNA bands with P. californica and P. pinnata, respectively; phylogenetic analysis indicated equally distant relationships to both species. Pikea yoshizakii or a closely similar species with the same life history occurs in southern California and Mexico.     

Same species,different population dynamics: Spatio-temporal differences of Undaria pinnatifida (Ochrophyta,Phaeophyceae) in the intertidal of North Patagonia,Argentina

Population dynamics can be influenced by physical and biological factors, particularly in stressful environments. Introduced species usually have great physiological plasticity, resulting in populations with different traits. Undaria pinnatifida, a macroalga originally described from northeast Asia, was introduced in Northern Patagonia, Argentina (San Matías Gulf) around 2010. To describe the spatio-temporal variability in population structure and morphometry of U. pinnatifida, we conducted monthly field samplings for 2 years at the intertidal area of two contrasting sites in the San Matías Gulf. Individuals of U. pinnatifida were classified by developmental stage, and their morpho-gravimetric variables were measured. In both intertidal sites juveniles were found in higher proportion during austral autumn and grew and matured during the autumn-winter months (from May onwards), and individuals senesced during early austral summer (December and January). Conversely, density and biomass were largely different between sites, and individuals showed slight morphological variability between sites. Environmental (e.g., nutrient concentration, available substrate) and biological factors (e.g., facilitation, competition) may explain the observed differences. Since there is not a macroalga with U. pinnatifida morphometrical characteristics in the intertidal environments of San Matías Gulf, studying this recent introduction gives us a better understanding of its potential ecological effects.     

Ecological distribution and phenology of an invasive species, Cardamine hirsuta L., and its native counterpart, Cardamine flexuosa With., in central Japan

Cardamine hirsuta is a European species that was recently introduced into Japan and its wide distribution has been confirmed in the Kanto district. To understand mechanisms of the recent spread of C. hirsuta in Japan, a comparative study of the alien species and its native congeneric species, C. flexuosa, was conducted. Habitat preferences, phenology and seed germination were examined. Cardamine hirsuta and C. flexuosa showed distinctive habitat-preferences; the former was most common in open habitats created by recent man-made constructions, and the latter was common in rice paddy fields and surrounding areas. The results indicate that C. flexuosa is a year-long annual, with a mixed phenology of summer and winter germination and growth. Seed dormancy during summer was relatively weak for C. flexuosa, and some plants that germinated early in summer reproduced during the same summer–autumn period. Plants that germinated in late summer and autumn behaved as winter annuals. In rice paddy fields, C. flexuosa is a winter annual because germination is prevented by submergence during summer. Plants flower during the following spring and complete their life cycle before the fields are flooded for rice cultivation. Cardamine hirsuta showed strong seed dormancy during summer and behaved as a typical winter annual. Seeds of C. hirsuta were intolerant to submergence in water, a condition that breaks seed dormancy of C. flexuosa. The results explain the absence of C. hirsuta from rice paddy fields. It was concluded that the spread of C. hirsuta is attributable to the recent expansion of urban habitats created by human activity and has occurred without direct competition with C. flexuosa. Considering recent urbanization in many areas, it is suggested that C. hirsuta has been spreading rapidly in Japan.     

Reproductive patterns in annual legume species on an aridity gradient

Reproductive patterns are analysed in annual legumes of west Asia, and their relationships to increasing aridity determined by multivariate analysis. Dormancy, seed size, dispersal and fecundity are shown to be partially substitutable in terms of their effect on survival and population growth.The range of patterns show greatest diversity under mesic conditions in coastal, mediterranean areas with high winter rainfall, low incidence of frost and long growing season. Increasing aridity leads to increasing reproductive homogeneity, in which a subset of patterns-those composed of high levels of seed dormancy, high seed to pod ratios, restricted dispersal capabilities and early flowering-become predominant. These findings corroborate earlier theoretical and empirical evidence concerning desert annuals.The majority of widespread species are shown to possess arid-type patterns. This exerts considerable influence on both the type and degree of ecotypic differentiation within species. The only feature that responds consistently to climatic change is flowering time, particularly among species characterized by high seed dormancy. In the few widespread species that do not display arid-type characteristics, ecotypic differentiation appears more frequently in a larger suite of traits.The unequal environmental demands made on species showing different levels of dormancy (e.g. variation in length of growing season from year to year and place to place) leads to strong asymmetries governing the relationships between reproduction and ecological amplitude. In this respect arid-type strategists with high seed dormancy appear to have greater chances of expansion than others. This has implications when choosing pasture legumes to improve mediterranean grasslands.     

The reproductive cycle in the population of Saccostrea cuccullatta (Born) from the coast of Karachi,Pakistan

Periphytic diatom communities on clay tile and sterilized rock substrates were compared with those on natural substrates. Clay tiles yielded diatom communities with the least variability between replicate samples, and the greatest similarity to the natural substrate assemblage. The advantages of utilizing introduced substrate communities and problems encountered with their simulation of the natural substrate community are discussed.