scholarly journals Reply to comments by Gurvich et al. (2016) on “Fruiting phenology as a ‘‘triggering attribute’’ of invasion process: Do invasive species take advantage of seed dispersal service provided by native birds?”

2016 ◽  
Vol 18 (11) ◽  
pp. 3117-3118
Author(s):  
David L. Vergara-Tabares ◽  
Julieta Badini ◽  
Susana I. Peluc
Oryx ◽  
2003 ◽  
Vol 37 (2) ◽  
pp. 178-193 ◽  
Author(s):  
Philip E. Hulme

Biological invasions by non-indigenous species (NIS) are widely recognized as a significant component of human-caused global environmental change. However, the standard programme of mapping distributions, predicting future ranges, modelling species spread, assessing impacts, developing management guidelines and screening species suffers from a number of serious limitations. NIS distribution maps can often be as misleading as they are instructive. Perceptions of the intensity, scale and rate of invasion are a function of mapping resolution, and the lack of common mapping standards prevents accurate comparative assessments. Coarse resolution data may overestimate the role of climate in the invasion process relative to other variables such as land use or human population density. Climate envelopes have therefore been widely used to predict species future ranges, but often overestimate potential distributions. Without an appropriate mechanistic understanding of the invasion process, correlative approaches may misinterpret the relative risks posed by different NIS. In addition, statistical models of invasion fail to encapsulate the complexity of human-mediated dispersal, which includes such diverse processes as transatlantic timber trade, horticultural fashion and the continuing expansion of road networks. Screening tools based on species traits, taxonomy and/or invasion history can sometimes result in high discrimination rates. Yet where the cost of false positives outweighs the risks from false negatives, a higher discriminatory power is required. Certain research outputs have perhaps been counterproductive in the war against invasive species. Studies have highlighted that only a tiny proportion of NIS are invasive, that most invasions occur in human dominated rather than pristine ecosystems, that indigenous and non-indigenous species are sufficiently similar that their impacts may not necessarily be different, and that there is evidence that introduced species augment rather than reduce species diversity. It is crucial to address these wider perceptions of the problem in order to mobilize the resources necessary for a global invasive species management programme.


2014 ◽  
Vol 60 (3) ◽  
pp. 401-409 ◽  
Author(s):  
Sandra Hudina ◽  
Karlo Hock ◽  
Krešimir žganec

Abstract Traits that aid in the invasion process should exhibit a gradient across the expansion range in response to changing selection pressures. Aggression has been repeatedly associated with invasion success in many taxa, as it may help invaders to wrestle the resources from other species which enhances their success in a novel environment. However, aggression primarily allows individuals to overcome conspecific rivals, providing advantages in competition over resources. Agonistic prowess could therefore increase fitness at both ends of the expansion gradient. Here we review the role of aggression in range expansion of invasive species, and its potential role as a driver of range expansion. We analyze how these different mechanisms could affect trait variation in expanding and invasive populations. Specifically, we look at how aggression could help dilate the edges of a population through niche competition, as well as lead to exclusion from the center (i.e. areas of high population density) by the conspe-cifics. Both of these processes will result in a characteristic spatial distribution of phenotypes related to aggression that could provide insights into the ecological pressures and dynamics of expanding populations, potentially providing clues to their success as niche competitors and invasive species.


2019 ◽  
Vol 60 (1) ◽  
Author(s):  
Yu-Ting Huang ◽  
Ya-Fu Lee ◽  
Yen-Min Kuo ◽  
Sing-Yi Chang ◽  
Chia-Ling Wu

Abstract Background Figs are key resources for tropical frugivores and display unique fruiting patterns. While monoecious figs support both seeds and wasp rearing, dioecious plants perform the tasks separately and produce seeded figs in smaller asynchronous crops. Thus dioecious females, compared to monoecious figs, may afford to invest more efforts to maximize seediness, or increase fruit pulp, water content, and nutrient rewards to attract frugivores for better seed dispersal. Yet size variation among and within fig species in either breeding system may lead to complicated resource allocation. We assessed fruiting phenology, measured fig morphological traits, and analyzed fig nutrient contents of the monoecious Ficus caulocarpa and F. subpisocarpa and the dioecious F. ampelas and F. irisana in a sympatric tropical forest to investigate species differences and size effects on fig functional traits and their ecological correlates. Results All four species fruited nearly year-round. Monoecious figs’ inter-tree asynchronous crops had high peak mature crop sizes over much shorter fruiting periods than dioecious figs. Among trees, F. subpisocarpa and F. irisana were greater in fig-size and size variation, F. caulocarpa and F. ampelas comparatively displayed large variation in fig compositions. As fig size increased, water contents gradually increased in large-fig species, but seediness with a decreasing trend in small-fig species. Dioecious figs had lower pulp-seed ratio but tended to have higher water contents than monoecious figs, particularly within a similar size range. Dioecious figs also had higher carbohydrates, whereas monoecious figs contained higher fiber and lipid contents. Conclusions Our study revealed species differences in certain fig functional traits that were correlated with fig size or their breeding systems, with substantial inter-tree variation. This partially supported the predictions regarding their fruiting strategies of aiding seed dispersal by frugivores, yet suggests a fruiting plasticity of individual trees subject to environmental constraints and their biotic interactions.


2019 ◽  
Vol 27 (3) ◽  
pp. 276-290 ◽  
Author(s):  
R. I. Burda ◽  
S. N. Koniakin

The process of invasion, naturalization, dispersion and invasive activity of non-native woody species in 5 regional floras, 5 urban floras and over 30 floras of the protected areas is discussed. It has been established that 182 non-native species out of 95 genera and 45 families are currently at different naturalization stages in the spontaneous flora of Ukraine. In terms of life-forms, they may be divided as follows: trees – 41%, shrubs – 35%, trees/shrubs – 15%, lianas – 9%. Most species spread both via seed dispersal and the vegetative way – 56%, using only seed dispersal – 42%, only the vegetative way – 2%. According to the preliminary rating of species-wise invasive activity, 71 species (40%) have naturalized completely, among them 20 invasive species, including 12 transformer species, 29 potentially invasive species, and 22 naturalized species which demonstrate no invasive tendencies. The initial stages of invasion of 111 species are as follows: introduction – 9%, survival – 36%, adaptation of the reproductive sphere – 28%, establishment, formative of local populations – 27%. In terms of dispersion, non-naturalized species are divided as follows: rare – 45%, local – 16%, sporadic – 6%, unique – 12%, spreading under control beyond collections and expositions in botanical gardens and arboretums – 21%. Twelve transformer species, the greatest threat to local diversity, are Acer negundo, Ailanthus altissima, Amorpha fruticosa, Bupleurum fruticosum, Elaeagnus angustifolia, E. rhamnoides, Fraxinus ornus, Parthenocissus quinquefolia, P. vitacea, Robinia pseudoacacia, Rhamnus alaternus, Salix × blanda and 8 invasive proper species: Berberis aquifolia, Colutea orientalis, Daphne laureola, Prunus cerasifera, P. serotina, Quercus ilex, Viburnum tinus, Vitis vinifera. The list of alien species, most widespread in 50 regions of Europe, includes Robinia pseudoacacia (42 regions), Ailanthus altissima (40), Acer negundo (38), Prunus cerasus (34), Quercus rubra (34), Rosa rugosa (34), Prunus domestica (31). The mitigation of the impacts of these species on local biodiversity is possible via the restoration of local native plant communities, land use organization, strict selection of introduced species prior to the introduction, culture of planting management, preventive measures and extending awareness and sharing of information about plant invasions. Therefore, Ukraine’s spontaneous flora is notable for the active process of naturalization of non-native woody species with considerable involvement of invasive alien species. This is the first and preliminary evaluation of the invasive activity of woody species in Ukraine’s flora. The manifestations of the global tendency of increased involvement and invasive activity of alien woody species in domestic flora have been confirmed. These conclusions are also relevant for elaborating the system of preventive, containing and mitigating measures regarding plant invasions in Ukraine.


Sign in / Sign up

Export Citation Format

Share Document