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.     

Non-indigenous marine species of the Azores

Marine benthic species introduced to the Azores are collated from scientific publications, internal reports and own data. Twelve algae and 21 invertebrates are classified as non-indigenous species, 18 as cryptogenic. Two species of algae and two ascidians are regarded as particularly invasive along the shores of this oceanic archipelago.     

Trends and rates of microevolution in plants

Evidence for rapid evolutionary change in plants in response to changing environmental conditions is widespread in the literature. However, evolutionary change in plant populations has not been quantified using a rate metric that allows for comparisons between and within studies. One objective of this paper is to estimate rates of evolution using data from previously published studies to begin a foundation for comparison and to examine trends and rates of microevolution in plants. We use data gathered from studies of plant adaptations in response to heavy metals, herbicide, pathogens, changes in pH, global change, and novel environments. Rates of evolution are estimated in the form of two metrics, darwins and haldanes. A second objective is to demonstrate how estimated rates could be used to address specific microevolutionary questions. For example, we examine how evolutionary rate changes with time, life history correlates of evolutionary rates, and whether some types of traits evolve faster than others. We also approach the question of how rates can be used to predict patterns of evolution under novel selection pressures using two contemporary examples: introductions of non-native species to alien environments and global change.     

Adaptation to the new land or effect of global warming? An age-structured model for rapid voltinism change in an alien lepidopteran pest

1. Hyphantria cunea Drury invaded Japan at Tokyo in 1945 and expanded its distribution gradually into northern and south-western Japan. All populations in Japan were bivoltine until the early 1970s, at which time trivoltine populations appeared in several southern regions. Presently, H. cunea exists as separate bivoltine and trivoltine populations divided around latitude 36 degrees . In the course of this voltinism change, the mean surface temperature in Japan rose by 1.0 degrees C. 2. To determine whether and how this temperature increase might be responsible for the voltinism change, we constructed an age-structured model incorporating growth speed driven by actual daily temperature and detailed mechanisms of diapause induction triggered by both daily photoperiod and temperature. 3. The simulation result suggests that both the acceleration of the growth speed and the prolongation of diapause induction are necessary to cause changes in voltinism, regardless of temperature increase. We concluded that the H. cunea population changed its life-history traits as an adaptation parallel with its invasion into the south-western parts of Japan. 4. Though the temperature increase had little effect on the fitness and heat stress in bivoltine and trivoltine populations, the trivoltine life cycle has become advantageous at least in marginal regions such as Tokyo.     

Naiveté and Novel Perturbations: Conservation of Native Spiders on an Oceanic Island System

The native fauna of isolated island systems is generally unique with acute conservation issues. For spiders in Hawaii, the first impediment to effective conservation is lack of taxonomic knowledge. The primary conservation concerns are related to the highly localized areas of endemicity of many species, with associated small population sizes. Species on insular systems tend to occur naturally in small populations, and small population size itself may not be a cause for conservation concern. However, for spiders and other arthropods, which tend to have shorter generation times compared to vertebrates, population fluctuations will tend to be more frequent, rendering them more vulnerable to extinction through demographic accidents at small population size. The knowledge we have to date suggests that habitat disturbance and alien species invasion are probably the major factors affecting native spiders in the islands. For a given natural community, the ability of species to accommodate habitat perturbation may be related more to the novelty of the perturbation than to its apparent severity. Although native spiders appear to tolerate disruption of the species composition of the native vegetation, evidence suggests that they are severely impacted by alien arthropod predators, in particular social hymenoptera, a group not represented among native Hawaiian arthropods.     

Assessing the speed and predictability of local adaptation in invasive California poppies (Eschscholzia californica)

Insight into the speed and predictability of local adaptation can be gained by studying organisms, such as invasive species, that have recently expanded their geographical ranges. Common garden studies were designed to address these issues with the California poppy, Eschscholzia californica, collected from a wide range of environments in both its native (California) and invasive (Chile) ranges. We found similar patterns of plant trait variation along similar abiotic gradients in plants collected from both areas. Multivariate analysis demonstrated that coastal plants from both areas tended to be shorter, smaller plants with smaller seeds and flowers that germinate and flower later than plants collected from inland locations. In addition, size and fecundity traits in both native and invasive poppies were correlated with average rainfall totals; the plants that grew the largest and were the most fecund during the first year of growth originated from the driest areas. This parallel variation suggests that these traits are adaptive and that these patterns have evolved in Chile during the 110-150 years since introduction.