Area Of Range Expansion Research Articles

Landscape Composition Affects Elements of Metacommunity Structure for Culicidae Across South-Eastern Illinois.

The interplay among invasive alien vectors and the species assemblage of native potential vectors in areas of range expansion may affect the dynamics of pathogen transmission. In this study we investigate how Aedes albopictus, an invasive mosquito of considerable public health concern fits within mosquito communities at the edge of its range of distribution. This was addressed using a 2-year field survey of mosquitoes in south-eastern Illinois. We found that Ae. albopictus was more broadly distributed in this region than previously realized, with new occurrence records for nine counties. Abundance of this species varied strongly and peaked in locations of low-intermediate overall mosquito species richness. This differed from overall mosquito abundance, as well as abundance of another important vector, Cx. pipiens, for which the abundance-richness relationships were best described with power functions. Metacommunity analyses revealed that mosquito communities showed a non-random distribution with a Clementsian gradient, which suggests a pattern whereby distinct species assemblages are associated with specific habitats or environmental conditions. Land use was a significant underlying factor shaping mosquito community structure and species assemblages. Multivariate analyses showed that while Ae. canadensis and Cx. pipiens complex mosquitoes were associated with high and low proportions of wetlands in the environment, respectively, Ae. albopictus was most strongly associated with urban settlements. This work sheds light on landscape-level processes, such as niche differentiation driven by urban and agricultural development, structuring mosquito communities. We suggest that mosquito community assessments across habitats be incorporated as part of a One Health vector surveillance approach to aid in the goal of prediction and prevention of new and (re-)emerging vector-borne diseases.

On the Fairness of Range Expansion With Interference Mitigation in Heterogeneous Networks

A fair range expansion (RE) with interference mitigation scheme is exploited for heterogeneous networks (HetNet) in which picocells is overlaid with macrocells. In this strategy, not only the bias value of range expansion but also the number of users attached to the picocell is considered to improve the fairness of user association. According to the ratio of the users in the area of range expansion, certain portion of the system spectrum resources are intelligently scheduled, on which the transmit power of macro base station (MBS) is optimized via pricing-based algorithm to alleviate the macrocell's interference to the picocell users in the range expansion zone. Fairness indexes of inter-tier and intra-tier are introduced to evaluate the association fairness of users between and within the two tiers respectively. Simulation results demonstrate that the proposed method can provide greater system fairness and capacity, especially when large bias value of RE is configured.

Range expansion dynamics of the invasive round goby (Neogobius melanostomus) in a river system

The rates of upstream and downstream range expansion of the round goby (Neogobius melanostomus) were examined in the Trent-Severn Waterway in 2009 and 2010. Relative abundance, demographics, and habitat use were also compared between areas of range expansion and a longer established area to determine how these characteristics varied along the invasion pathway. Round gobies were sampled using an angling removal method in May and August of 2009 and 2010 at 75 sites at each area of range expansion and 25 sites near the center of their range where they first became established in the waterway. Areas of range expansion had initially low abundance and low site occupancy in May 2009 relative to the longer established area. Large increases in abundance and site occupancy were observed over the first summer of occupation, but with limited range expansion. Rapid range expansion was observed during the non-reproductive season at the upstream edge of range. Individuals sampled in the expanded upstream range were small and female biased relative to other range locations. Round gobies also exhibited higher habitat selectivity for rocky substrates at range edges than in the longer established area. These characteristics of seasonal dispersal, biased demographics of dispersers, and high habitat selectivity may be important components of successful range expansion of the round goby in invaded ecosystems.

The Role of Environmental Factors in the Northeastern Range Expansion ofPapilio cresphontesCramer (Papilionidae)

The Giant Swallowtail butterfly, Papilio cresphontes Cramer (Papilionidae), has been reported in New York State for nearly 150 years. In recent years there has been an unexplained increase in P. cresphontes occurrences along the northeastern periphery of its geographical range. This study examined historical records to describe the movement of P. cresphontes populations into New York State and adjacent Ontario. Climate data and field studies were used to identify environmental factors that may influence the range expansion, which was found to correspond with an absence of September frosts beginning in 2001. Field studies indicated that some P. cresphontes larvae were capable of withstanding multiple frosts and descended to pupate normally into late October in the range expansion area. Although the larvae may have adapted to endure cooler temperatures to some degree, the effects of warming temperatures on other factors such as natural enemies and larval host plant quality in autumn may influence the spread of P. cresphontes populations at least as much as larval frost tolerance.

Survival at low temperature of larvae of the pine processionary moth Thaumetopoea pityocampa from an area of range expansion

Abstract1 Larvae of Thaumetopoea pityocampa (Lepidoptera: Notodontidae) develop throughout the winter, although their feeding activity and survival can be impaired by adverse climatic factors. The present study investigated the survival at low temperature of larvae originating from a population with range expansion in an alpine valley in Northern Italy.2 The supercooling point of individually analysed larvae averaged at −7 °C. This value insufficiently described the cold hardiness of the larvae; 39% of the tested larvae were alive when returned to room temperature immediately after freezing. When larval colonies inside their nest were exposed to −17 °C for 1 h after gradual temperature decrease, survival was 70.4%.3 Rearing of larvae in the laboratory at different day/night temperatures indicated an effect of cumulative chill injury on larvae. A logistic regression explained the relationship between negative thermal sum (h°C below 0 °C) received in the laboratory experiment and larval survival. A similar relationship was demonstrated between negative thermal sum and survival of larval colonies in the field.4 In the laboratory experiment, some tested larvae were able to survive for up to 8 weeks without feeding depending on rearing temperature. As expected, feeding occurred only when larvae were reared at temperatures of 9 °C day/0 °C night.5 We classify the larvae of T. pityocampa as being moderate freezing tolerant. The winter behaviour allows this species to track climate warming by a rapid expansion into those areas that become compatible with the insect’s development.

Incursion and range expansion in the bluetongue vector Culicoides imicola in the Mediterranean basin: a phylogeographic analysis

The bluetongue (BT) vector Culicoides imicola Kieffer (Diptera: Ceratopogonidae) has undergone widespread range expansion across most of the Mediterranean basin, concomitant with the largest BT epizootic outbreaks on record. Knowledge of the substructure of this vector expansion would be useful for identifying specific source-expansion systems. To this end we analysed the haplotype diversity of the mitochondrial cytochrome oxidase I gene in 273 C. imicola from 88 Mediterranean sites and outgroups. All the C. imicola haplotypes (n = 26) formed a single, distinct clade in comparison with haplotypes of four other species of the Imicola group from southern Africa, confirming C. imicola as a single phylospecies. Haplotype distribution showed extreme differentiation across the Mediterranean basin, with four common haplotypes each predominating in different areas. Eastern and western areas characterized by distinct BT incursions accounted for most of the molecular variance in haplotype composition. Shared common haplotypes identified one area of incursion and expansion encompassing the western half of the Mediterranean basin, with evidence of population growth, and another system encompassing Anatolian Turkey, the Aegean Islands and mainland Greece. A third area of range expansion was identified in the central Mediterranean, with a possible source in Algeria and unsampled parts of central North Africa. We conclude that the expansion of C. imicola in the Mediterranean basin consists of at least three incursions followed by expansions and that the western system experiences conditions promoting high population growth.