Assessing the potential impact of an invasive species on a Mediterranean amphibian assemblage: a morphological and ecological approach

Hydrobiologia ◽  
2011 ◽  
Vol 680 (1) ◽  
pp. 233-245 ◽  
Author(s):  
Daniel Escoriza ◽  
Dani Boix
2014 ◽  
Vol 83 (3) ◽  
pp. 251-255 ◽  
Author(s):  
Grzegorz Migdałek ◽  
Jolanta Kolczyk ◽  
Artur Pliszko ◽  
Maria Kościńska-Pająk ◽  
Aneta Słomka

Pollen and achene characters of natural interspecific hybrid <em>Solidago</em> ×<em>niederederi</em> Khek were analyzed and compared with putative parental species <em>S. virgaurea</em> L. and <em>S. canadensis</em> L. to estimate the level of disturbances in generative reproduction resulting from its hybrid nature. Pollen viability (stainability) of <em>Solidago</em> ×<em>niederederi</em> from one newly discovered locality in NE Poland was evidently reduced to ~65% in both viability tests (acetocarmine and Alexander). The diameter of viable pollen (median 21.11 µm) fell between <em>S. canadensis</em> (median 19.52 µm) and <em>S. virgaurea</em> (median 23.48 µm). Both parental species produced normally developed achenes with high frequency (~90%) whereas in the hybrid, the seed set was dramatically low (6%). The results clearly indicated that sexual reproduction of hybridogenous taxon <em>S.</em> ×<em>niederederi</em> is disturbed, and its potential impact as an invasive species depends mainly on vegetative propagation.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Luis B. Gabín-García ◽  
Carolina Bartolomé ◽  
Carla Guerra-Tort ◽  
Sandra V. Rojas-Nossa ◽  
José Llovo ◽  
...  

AbstractInvasive species contribute to deteriorate the health of ecosystems due to their direct effects on native fauna and the local parasite-host dynamics. We studied the potential impact of the invasive hornet Vespa velutina on the European parasite-host system by comparing the patterns of diversity and abundance of pathogens (i.e. Microsporidia: Nosematidae; Euglenozoa: Trypanosomatidae and Apicomplexa: Lipotrophidae) in European V. velutina specimens with those in the native European hornet Vespa crabro, as well as other common Hymenoptera (genera Vespula, Polistes and Bombus). We show that (i) V. velutina harbours most common hymenopteran enteropathogens as well as several new parasitic taxa. (ii) Parasite diversity in V. velutina is most similar to that of V. crabro. (iii) No unambiguous evidence of pathogen release by V. velutina was detected. This evidence together with the extraordinary population densities that V. velutina reaches in Europe (around of 100,000 individuals per km2 per year), mean that this invasive species could severely alter the native pathogen-host dynamics either by actively contributing to the dispersal of the parasites and/or by directly interacting with them, which could have unexpected long-term harmful consequences on the native entomofauna.


2021 ◽  
Author(s):  
Oxana Munjiu ◽  

In this study the author presents data on the density, biomass and diversity of macrobenthos along the Prut River in 2020. There are data on groups more sensitive to environmental changes and anthropogenic impact, collection points of interest in terms of species conservation due to the presence of rare species, the potential impact of invasive species.


2018 ◽  
Vol 11 (4) ◽  
pp. 163-174 ◽  
Author(s):  
Qinfeng Guo ◽  
Dale G. Brockway ◽  
Diane L. Larson ◽  
Deli Wang ◽  
Hai Ren

AbstractCommon practices for invasive species control and management include physical, chemical, and biological approaches. The first two approaches have clear limitations and may lead to unintended (negative) consequences, unless carefully planned and implemented. For example, physical removal rarely completely eradicates the targeted invasive species and can cause disturbances that facilitate new invasions by nonnative species from nearby habitats. Chemical treatments can harm native, and especially rare, species through unanticipated side effects. Biological methods may be classified as biocontrol and the ecological approach. Similar to physical and chemical methods, biocontrol also has limitations and sometimes leads to unintended consequences. Therefore, a relatively safer and more practical choice may be the ecological approach, which has two major components: (1) restoration of native species and (2) biomass manipulation of the restored community, such as selective grazing or prescribed burning (to achieve and maintain viable population sizes). Restoration requires well-planned and implemented planting designs that consider alpha-, beta-, and gamma-diversity and the abundance of native and invasive component species at local, landscape, and regional levels. Given the extensive destruction or degradation of natural habitats around the world, restoration could be most effective for enhancing ecosystem resilience and resistance to biotic invasions. At the same time, ecosystems in human-dominated landscapes, especially those newly restored, require close monitoring and careful intervention (e.g., through biomass manipulation), especially when successional trajectories are not moving as intended. Biomass management frequently uses prescribed burning, grazing, harvesting, and thinning to maintain overall ecosystem health and sustainability. Thus, the resulting optimal, balanced, and relatively stable ecological conditions could more effectively limit the spread and establishment of invasive species. Here we review the literature (especially within the last decade) on ecological approaches that involve biodiversity, biomass, and productivity, three key community/ecosystem variables that reciprocally influence one another. We focus on the common and most feasible ecological practices that can aid in resisting new invasions and/or suppressing the dominance of existing invasive species. We contend that, because of the strong influences from neighboring areas (i.e., as exotic species pools), local restoration and management efforts in the future need to consider the regional context and projected climate changes.


2006 ◽  
Vol 12 (1) ◽  
pp. 40 ◽  
Author(s):  
James G. Smith ◽  
Ben L. Phillips

Cane Toads Bufo marinus are a highly successful invasive species, having invaded more than twenty countries in the last 150 years. In Australia, they currently occupy more than 1 million square kilometres. Toads are highly toxic and Australian predators have no evolutionary history with the cardiac toxins in toad skin. As such, toads constitute a novel and extremely toxic prey for Australia's predators. Australia's reptiles are perhaps the largest group likely to be affected by the invasion of the toad. By examining species distributions, we conclude that 59% of agamids, 85% of the varanids and all of Australia's crocodiles and freshwater turtles are potentially at risk from toads. We then assayed eleven species of reptile; one freshwater turtle (Chelidae), two crocodiles (Crocodylidae), two dragons (Agamidae), one python (Pythonidae) and five species of monitor (Varanidae) for resistance to toad toxin. We found a high level of variation between species in resistance to toad toxin but in all cases (except for one species of crocodile) all species were easily capable of eating a toad large enough to kill them. We conclude that toads pose a real and ongoing threat to the majority of Australian reptile species we examined.


2019 ◽  
Vol 62 (11) ◽  
pp. 4001-4014
Author(s):  
Melanie Weirich ◽  
Adrian Simpson

Purpose The study sets out to investigate inter- and intraspeaker variation in German infant-directed speech (IDS) and considers the potential impact that the factors gender, parental involvement, and speech material (read vs. spontaneous speech) may have. In addition, we analyze data from 3 time points prior to and after the birth of the child to examine potential changes in the features of IDS and, particularly also, of adult-directed speech (ADS). Here, the gender identity of a speaker is considered as an additional factor. Method IDS and ADS data from 34 participants (15 mothers, 19 fathers) is gathered by means of a reading and a picture description task. For IDS, 2 recordings were made when the baby was approximately 6 and 9 months old, respectively. For ADS, an additional recording was made before the baby was born. Phonetic analyses comprise mean fundamental frequency (f0), variation in f0, the 1st 2 formants measured in /i: ɛ a u:/, and the vowel space size. Moreover, social and behavioral data were gathered regarding parental involvement and gender identity. Results German IDS is characterized by an increase in mean f0, a larger variation in f0, vowel- and formant-specific differences, and a larger acoustic vowel space. No effect of gender or parental involvement was found. Also, the phonetic features of IDS were found in both spontaneous and read speech. Regarding ADS, changes in vowel space size in some of the fathers and in mean f0 in mothers were found. Conclusion Phonetic features of German IDS are robust with respect to the factors gender, parental involvement, speech material (read vs. spontaneous speech), and time. Some phonetic features of ADS changed within the child's first year depending on gender and parental involvement/gender identity. Thus, further research on IDS needs to address also potential changes in ADS.


2020 ◽  
Vol 63 (7) ◽  
pp. 2281-2292
Author(s):  
Ying Zhao ◽  
Xinchun Wu ◽  
Hongjun Chen ◽  
Peng Sun ◽  
Ruibo Xie ◽  
...  

Purpose This exploratory study aimed to investigate the potential impact of sentence-level comprehension and sentence-level fluency on passage comprehension of deaf students in elementary school. Method A total of 159 deaf students, 65 students ( M age = 13.46 years) in Grades 3 and 4 and 94 students ( M age = 14.95 years) in Grades 5 and 6, were assessed for nonverbal intelligence, vocabulary knowledge, sentence-level comprehension, sentence-level fluency, and passage comprehension. Group differences were examined using t tests, whereas the predictive and mediating mechanisms were examined using regression modeling. Results The regression analyses showed that the effect of sentence-level comprehension on passage comprehension was not significant, whereas sentence-level fluency was an independent predictor in Grades 3–4. Sentence-level comprehension and fluency contributed significant variance to passage comprehension in Grades 5–6. Sentence-level fluency fully mediated the influence of sentence-level comprehension on passage comprehension in Grades 3–4, playing a partial mediating role in Grades 5–6. Conclusions The relative contributions of sentence-level comprehension and fluency to deaf students' passage comprehension varied, and sentence-level fluency mediated the relationship between sentence-level comprehension and passage comprehension.


2017 ◽  
Vol 61 (2) ◽  
pp. 51-68 ◽  
Author(s):  
Wolfgang Georg Weber ◽  
Hans Jeppe Jeppesen

Abstract. Connecting the social cognitive approach of human agency by Bandura (1997) and activity theory by Leontiev (1978) , this paper proposes a new theoretical framework for analyzing and understanding employee participation in organizational decision-making. Focusing on the social cognitive concepts of self-reactiveness, self-reflectiveness, intentionality, and forethought, commonalities, complementarities, and differences between both theories are explained. Efficacy in agency is conceived as a cognitive foundation of work motivation, whereas the mediation of societal requirements and resources through practical activity is conceptualized as an ecological approach to motivation. Additionally, we discuss to which degree collective objectifications can be understood as material indicators of employees’ collective efficacy. By way of example, we explore whether an integrated application of concepts from both theories promotes a clearer understanding of mechanisms connected to the practice of employee participation.


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