scholarly journals Impacts of a Non-indigenous Ecosystem Engineer, the American Beaver (Castor canadensis), in a Biodiversity Hotspot

2021 ◽  
Vol 2 ◽  
Author(s):  
Jonathan Q. Richmond ◽  
Camm C. Swift ◽  
Thomas A. Wake ◽  
Cheryl S. Brehme ◽  
Kristine L. Preston ◽  
...  
Keyword(s):  
Native Species ◽  
Ecosystem Engineer ◽  
Castor Canadensis ◽  
Trophic Dynamics ◽  
The Novel ◽  
Historical Survey ◽  
The Past ◽  
Invasive Predators ◽  
Per Capita ◽  
American Beaver

Non-native species having high per capita impacts in invaded communities are those that modulate resource availability and alter disturbance regimes in ways that are biologically incompatible with the native biota. In areas where it has been introduced by humans, American beaver (Castor canadensis) is an iconic example of such species due to its capacity to alter trophic dynamics of entire ecosystems and create new invasional pathways for other non-native species. The species is problematic in several watersheds within the Southern California-Northern Baja California Coast Ecoregion, a recognized hotspot of biodiversity, due to its ability to modify habitat in ways that favor invasive predators and competitors over the region's native species and habitat. Beaver was deliberately introduced across California in the mid-1900s and generally accepted as non-native to the region up to the early 2000s; however, articles promoting the idea that beaver may be a natural resident have gained traction in recent years, due in large part to the species' charismatic nature rather than by presentation of sound evidence. Here, we discuss the problems associated with beaver disturbance and its effects on conserving the region's native fauna and flora. We refute arguments underlying the claim that beaver is native to the region, and review paleontological, zooarchaeological, and historical survey data from renowned field biologists and naturalists over the past ~160 years to show that no evidence exists that beaver arrived by any means other than deliberate human introduction. Managing this ecosystem engineer has potential to reduce the richness and abundance of other non-native species because the novel, engineered habitat now supporting these species would diminish in beaver-occupied watersheds. At the same time, hydrologic functionality would shift toward more natural, ephemeral conditions that favor the regions' native species while suppressing the dominance of the most insidious invaders.

scholarly journals Raised by aliens: constant exposure to an invasive predator triggers morphological but not behavioural plasticity in a threatened species tadpoles

2021 ◽  
Author(s):  
Andrea Melotto ◽  
Gentile Francesco Ficetola ◽  
Roberta Pennati ◽  
Nicoletta Ancona ◽  
Raoul Manenti
Keyword(s):  
Phenotypic Plasticity ◽  
Native Species ◽  
Procambarus Clarkii ◽  
Muscle Size ◽  
Behavioural Plasticity ◽  
The Novel ◽  
Population Declines ◽  
Selective Pressures ◽  
Invasive Predators ◽  
Behavioural Tests

AbstractDuring biotic invasions, native communities are abruptly exposed to novel and often severe selective pressures. The lack of common evolutionary history with invasive predators can hamper the expression of effective anti-predator responses in native prey, potentially accelerating population declines. Nonetheless, rapid adaptation and phenotypic plasticity may allow native species to cope with the new ecological pressures. We tested the hypothesis that phenotypic plasticity is fostered when facing invasive species and evaluated whether plasticity offers a pool of variability that might help the fixation of adaptive phenotypes. We assessed behavioural and morphological trait variation in tadpoles of the Italian agile frog (Rana latastei) in response to the invasive crayfish predator, Procambarus clarkii, by rearing tadpoles under different predation-risk regimes: non-lethal crayfish presence and crayfish absence. After two-month rearing, crayfish-exposed tadpoles showed a plastic shift in their body shape and increased tail muscle size, while behavioural tests showed no effect of crayfish exposure on tadpole behaviour. Furthermore, multivariate analyses revealed weak divergence in morphology between invaded and uninvaded populations, while plasticity levels were similar between invaded and uninvaded populations. Even if tadpoles displayed multiple plastic responses to the novel predator, none of these shifts underwent fixation after crayfish arrival (10–15 years). Overall, these findings highlight that native prey can finely tune their responses to invasive predators through plasticity, but the adaptive value of these responses in whitstanding the novel selective pressures, and the long-term consequences they can entail remain to be ascertained.

scholarly journals Ocean acidification increases the vulnerability of native oysters to predation by invasive snails

2014 ◽  
Vol 281 (1778) ◽  
pp. 20132681 ◽  
Author(s):  
Eric Sanford ◽  
Brian Gaylord ◽  
Annaliese Hettinger ◽  
Elizabeth A. Lenz ◽  
Kirstin Meyer ◽  
...  
Keyword(s):  
Ocean Acidification ◽  
Native Species ◽  
Global Environmental Change ◽  
Interaction Strength ◽  
Ecological Impacts ◽  
Invasive Predators ◽  
Global Environmental ◽  
Common Response ◽  
Per Capita ◽  
Olympia Oysters

There is growing concern that global environmental change might exacerbate the ecological impacts of invasive species by increasing their per capita effects on native species. However, the mechanisms underlying such shifts in interaction strength are poorly understood. Here, we test whether ocean acidification, driven by elevated seawater p CO 2 , increases the susceptibility of native Olympia oysters to predation by invasive snails. Oysters raised under elevated p CO 2 experienced a 20% increase in drilling predation. When presented alongside control oysters in a choice experiment, 48% more high-CO 2 oysters were consumed. The invasive snails were tolerant of elevated CO 2 with no change in feeding behaviour. Oysters raised under acidified conditions did not have thinner shells, but were 29–40% smaller than control oysters, and these smaller individuals were consumed at disproportionately greater rates. Reduction in prey size is a common response to environmental stress that may drive increasing per capita effects of stress-tolerant invasive predators.

scholarly journals Beavers

2017 ◽  
Author(s):  
Jimmy D. Taylor ◽  
Greg K. Yarrow ◽  
James E. Miller
Keyword(s):  
Ecosystem Function ◽  
Biological Diversity ◽  
Ecosystem Engineer ◽  
Castor Canadensis ◽  
Keystone Species ◽  
Basic Information ◽  
Dam Building ◽  
The Many ◽  
American Beaver ◽  
New Habitats

The American beaver (Castor canadensis) is known as an “ecosystem engineer” because of the benefits their dams provide to biological diversity and ecosystem function. It also is considered a “keystone species” because of its ability to transform its environment, creating new habitats upon which other species depend. Despite the many positive benefits beavers provide through foraging and dam building, beavers also create conflict with people when their activities cause damage. The focus of this publication is to provide basic information on beaver ecology, damage, and management.

scholarly journals Distribution patterns of the native Eurasian and the non-native North American beaver in Finland—possible factors affecting the slow range expansion of the native species

2021 ◽  
Author(s):  
Riikka Alakoski ◽  
Kaarina Kauhala ◽  
Vesa Selonen
Keyword(s):  
Population Dynamics ◽  
North American ◽  
Range Expansion ◽  
Native Species ◽  
Castor Canadensis ◽  
Distribution Patterns ◽  
Movement Behavior ◽  
Eurasian Beaver ◽  
Native North American ◽  
American Beaver

AbstractDistribution patterns of species are affected by resource availability, dispersal, disturbance and population dynamics. The smaller population size and range of the native Eurasian beaver (Castor fiber) compared to the non-native North American beaver (Castor canadensis) in Finland raise questions on reasons for the slower range expansion of the native species. We compared the population growth rates and the spread of both species from their release sites. We also studied the factors possibly affecting the spread of the Eurasian beaver in South western Finland in more detail. We found that the North American beaver has spread longer distances than the Eurasian beaver, but we did not find evidence for movement barriers constraining the expansion rate of the native species. Lack of high-quality habitats does not seem to constrain the expansion to nearby areas either. Despite this, the Eurasian beaver population has grown to a high density close to its reintroduction site, and it has started to spread to novel areas only recently. We conclude that the expansion of the native beaver in Finland seems to be controlled by factors other than those related to barriers for movement: movement behavior and population dynamics, which require further investigation.

Hydraulic Laboratory at University of Liège

2018 ◽  
pp. 80-89
Author(s):  
Willi H. Hager
Keyword(s):  
Basic Research ◽  
The Novel ◽  
University Campus ◽  
Current Position ◽  
Professional Background ◽  
The Past ◽  
Comprehensive Picture

The Hydraulic Laboratory of Liège University, Belgium, is historically considered from its foundation in 1937 to the mid-1960s. The technical facilities of the various Buildings are highlighted, along with canals and instrumentation available. It is noted that in its initial era, comparatively few basic research has been conducted, mainly due to the professional background of the professors leading the establishment. This state was improved in the past 50 years, however, particularly since the Laboratory was dislocated to its current position in the novel University Campus. Biographies of the leading persons associated with the Liège Hydraulic Laboratory are also presented, so that a comprehensive picture is given of one of the currently leading hydraulic Laboratories of Europe.

High predatory efficiency and abundance drive expected ecological impacts of a marine invasive fish

2020 ◽  
Vol 637 ◽  
pp. 195-208 ◽  
Author(s):  
EM DeRoy ◽  
R Scott ◽  
NE Hussey ◽  
HJ MacIsaac
Keyword(s):  
Invasive Species ◽  
Native Species ◽  
Ecological Impact ◽  
Marine Species ◽  
Ecological Impacts ◽  
Negative Effects ◽  
Marine Predator ◽  
Eastern Gulf Of Mexico ◽  
Red Grouper ◽  
Per Capita

The ecological impacts of invasive species are highly variable and mediated by many factors, including both habitat and population abundance. Lionfish Pterois volitans are an invasive marine species which have high reported detrimental effects on prey populations, but whose effects relative to native predators are currently unknown for the recently colonized eastern Gulf of Mexico. We used functional response (FR) methodology to assess the ecological impact of lionfish relative to 2 functionally similar native species (red grouper Epinephelus morio and graysby grouper Cephalopholis cruentata) foraging in a heterogeneous environment. We then combined the per capita impact of each species with their field abundance to obtain a Relative Impact Potential (RIP). RIP assesses the broader ecological impact of invasive relative to native predators, the magnitude of which predicts community-level negative effects of invasive species. Lionfish FR and overall consumption rate was intermediate to that of red grouper (higher) and graysby grouper (lower). However, lionfish had the highest capture efficiency of all species, which was invariant of habitat. Much higher field abundance of lionfish resulted in high RIPs relative to both grouper species, demonstrating that the ecological impact of lionfish in this region will be driven mainly by high abundance and high predator efficiency rather than per capita effect. Our comparative study is the first empirical assessment of lionfish per capita impact and RIP in this region and is one of few such studies to quantify the FR of a marine predator.

The Pornographer and McGahern's Allusive Practice

2017 ◽  
Vol 47 (2) ◽  
pp. 281-297
Author(s):  
Tom Walker
Keyword(s):  
Social Practice ◽  
Literary Tradition ◽  
The Novel ◽  
Present Value ◽  
The Past

Allusions to other texts abound in John McGahern's fiction. His works repeatedly, though diffidently, refer to literary tradition. Yet the nature of such allusiveness is still unclear. This article focuses on how allusion in The Pornographer (1979) is depicted as an intellectual and social practice, embodying particular attitudes towards the function of texts and the knowledge they represent. Moreover, the critique of the practice of allusion that the novel undertakes is shown to have broader significance in terms of McGahern's whole oeuvre and its evolving attempts to salvage something of present value from the literature of the past.

Economic Performance and Public Finance in Kenya, 1960-2010

2018 ◽  
Vol 47 (2) ◽  
Author(s):  
Kempe Ronald Hope
Keyword(s):  
Public Finance ◽  
Economic Performance ◽  
Emerging Economy ◽  
The Other ◽  
Government Investment ◽  
The Past ◽  
Other Hand ◽  
Private Savings ◽  
Per Capita ◽  
Real Growth

Countries with positive per capita real growth are characterised by positive national savings—including government savings, increases in government investment, and strong increases in private savings and investment. On the other hand, countries with negative per capita real growth tend to be characterised by declines in savings and investment. During the past several decades, Kenya’s emerging economy has undergone many changes and economic performance has been epitomised by periods of stability, decline, or unevenness. This article discusses and analyses the record of economic performance and public finance in Kenya during the period 1960‒2010, as well as policies and other factors that have influenced that record in this emerging economy. 

A Review on Fast Dissolving Tablet

2017 ◽  
Vol 8 (03) ◽  
Author(s):  
Sagar T. Malsane ◽  
Smita S. Aher ◽  
R. B. Saudagar
Keyword(s):  
Drug Delivery ◽  
Patient Compliance ◽  
Research Area ◽  
Oral Route ◽  
Dosage Forms ◽  
The Novel ◽  
The Past ◽  
Orally Disintegrating Tablets ◽  
Novel Drug ◽  
Experience Difficulty

Oral route is presently the gold standard in the pharmaceutical industry where it is regarded as the safest, most economical and most convenient method of drug delivery resulting in highest patient compliance. Over the past three decades, orally disintegrating tablets (FDTs) have gained considerable attention due to patient compliance. Usually, elderly people experience difficulty in swallowing the conventional dosage forms like tablets, capsules, solutions and suspensions because of tremors of extremities and dysphagia. In some cases such as motion sickness, sudden episodes of allergic attack or coughing, and an unavailability of water, swallowing conventional tablets may be difficult. One such problem can be solved in the novel drug delivery system by formulating “Fast dissolving tablets” (FDTs) which disintegrates or dissolves rapidly without water within few seconds in the mouth due to the action of superdisintegrant or maximizing pore structure in the formulation. The review describes the various formulation aspects, superdisintegrants employed and technologies developed for FDTs, along with various excipients, evaluation tests, marketed formulation and drugs used in this research area.

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