scholarly journals From tameness to wariness: chemical recognition of snake predators by lizards in a Mediterranean island

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e2828 ◽  
Author(s):  
Abraham Mencía ◽  
Zaida Ortega ◽  
Valentín Pérez-Mellado
Keyword(s):  
Slow Motion ◽  
Predation Pressure ◽  
Main Island ◽  
Chemical Recognition ◽  
Introduced Predators ◽  
Podarcis Lilfordi ◽  
Podarcis Siculus ◽  
Mediterranean Island ◽  
Snake Predators ◽  
High Degree

Antipredatory defenses are maintained when benefit exceeds cost. A weak predation pressure may lead insular lizards to tameness.Podarcis lilfordiexhibits a high degree of insular tameness, which may explain its extinction from the main island of Menorca when humans introduced predators. There are three species of lizards in Menorca: the nativeP. lilfordi, only on the surrounding islets, and two introduced lizards in the main island,Scelarcis perspicillataandPodarcis siculus. In addition, there are three species of snakes, all introduced: one non-saurophagous (Natrix maura), one potentially non-saurophagous (Rhinechis scalaris) and one saurophagous (Macroprotodon mauritanicus). We studied the reaction to snake chemical cues in five populations: (1)P. lilfordiof Colom, (2)P. lilfordiof Aire, (3)P. lilfordiof Binicodrell, (4)S. perspicillata, and (5)P. siculus, ordered by increasing level of predation pressure. The three snakes are present in the main island, while onlyR. scalarisis present in Colom islet, Aire and Binicodrell being snake-free islets. We aimed to assess the relationship between predation pressure and the degree of insular tameness regarding scent recognition. We hypothesized thatP. lilfordishould show the highest degree of tameness,S. perspicillatashould show intermediate responses, andP. siculusshould show the highest wariness. Results are clear: neitherP. lilfordinorS. perspicillatarecognize any of the snakes, whileP. siculusrecognizes the scent ofM. mauritanicusand reacts to it with typical well-defined antipredatory behaviours as tail waving and slow motion. These results rise questions about the loss of chemical recognition of predators during island tameness and its related costs and benefits for lizards of insular habitats. In addition, this highlights the necessity for strong conservation measures to avoid the introduction of alien predators.

The yellow-legged gull as a predator of lizards in Balearic Islands

2014 ◽  
Vol 35 (2) ◽  
pp. 207-213 ◽  
Author(s):  
Valentín Pérez-Mellado ◽  
Mario Garrido ◽  
Zaida Ortega ◽  
Ana Pérez-Cembranos ◽  
Abraham Mencía
Keyword(s):  
Balearic Islands ◽  
Predation Pressure ◽  
Vertebrate Species ◽  
Sources Of Information ◽  
Mediterranean Islands ◽  
Lizard Species ◽  
Podarcis Lilfordi ◽  
Larus Michahellis ◽  
Plasticine Models ◽  
Different Sources

Lizards and gulls cohabit in several Mediterranean islands. The yellow-legged gull, Larus michahellis, was found to prey several vertebrate species. However, precise information about the interaction between gulls and other vertebrates, particularly with lizards is still scarce. The Balearic lizard, Podarcis lilfordi, shares several coastal islets with the yellow-legged gull. Using two different sources of information, we studied the interaction of both species in Colom Island (Menorca, Balearic Islands, Spain). We studied the diet of the yellow-legged gull and learnt that the Balearic lizard is not a common prey of the yellow-legged gull. On the other hand, we studied the potential predation pressure of gulls on lizards, using plasticine models of lizards. We did two different experiments from which we can conclude that yellow-legged gulls rarely attack lizards and, consequently, cannot be considered a major threat for this endemic lizard species, at least in the population under study. Finally, we obtained evidence that plasticine models can only be employed with caution to assess predation pressure of opportunistic scavengers, much as gulls are. The majority of marks on models were not the consequence of true attacks by gulls, but the result of ground exploratory behaviour of gulls in search of any edible matter. Therefore, contrary to popular belief, in the case of the yellow-legged gull, the proportion of marked models would be an indication of ground-based wandering activity, rather than a result of its predation pressure on lizards.

scholarly journals Mitigating impacts of invasive alien predators on an endangered sea duck amidst high native predation pressure

2021 ◽  
Author(s):  
Kim Jaatinen ◽  
Ida Hermansson ◽  
Bertille Mohring ◽  
Benjamin B Steele ◽  
Markus Öst
Keyword(s):  
American Mink ◽  
Predation Pressure ◽  
Nyctereutes Procyonoides ◽  
Predator Removal ◽  
Positive Effects ◽  
Invasive Predator ◽  
Introduced Predators ◽  
Invasion Impacts ◽  
Native Predator ◽  
Breeding Propensity

Abstract Invasive species represent a major threat to global biodiversity by causing population declines and extinctions of native species. The negative impacts of introduced predators are well documented, yet a fundamental knowledge gap exists regarding the efficiency of potential mitigation methods to restore the ecosystem. Other understudied aspects concern prey behavioural antipredator responses and the historical context of native predator-prey interactions, which may moderate invasion impacts on native prey. Invasion impacts of American mink (Neovison vison) and raccoon dog (Nyctereutes procyonoides) into the Baltic Sea archipelago are poorly understood, and the efficiency of removal efforts as a means to alleviate depredation pressure on native prey is debated. Here, we examine the effectiveness of invasive predator removal on ground-nesting female common eider (Somateria mollissima) mortality, breeding success and breeding propensity over a nine-year period, while controlling for predation risk imposed by the main native predator, the white-tailed eagle (Haliaeetus albicilla). Our results clearly show that intensified removal of American minks and raccoon dogs decreased the number of female eiders killed during nesting, while improving both nesting success and breeding propensity. Such obvious positive effects of invasive predator removal are particularly noteworthy against the backdrop of a soaring eagle population, indicating that the impacts of invasives may become accentuated when native predators differ taxonomically and by hunting mode. This study shows that invasive alien predator removal is a cost-efficient conservation measure clearly aiding native fauna even under severe native predation pressure. Such cost-effective conservation actions call for governmental deployment across large areas.

Islet tameness: escape behavior and refuge use in populations of the Balearic lizard (Podarcis lilfordi) exposed to differing predation pressure

2009 ◽  
Vol 87 (10) ◽  
pp. 912-919 ◽  
Author(s):  
William E. Cooper, Jr. ◽  
Dror Hawlena ◽  
Valentín Pérez-Mellado
Keyword(s):  
Escape Behavior ◽  
Predation Pressure ◽  
Limited Data ◽  
Refuge Use ◽  
Predator Prey ◽  
Antipredatory Behavior ◽  
Short Time Span ◽  
Podarcis Lilfordi ◽  
Short Time ◽  
Two Populations

Prey often exhibit reduced escape behavior on islands where predators are absent or scarce. Models of escape and refuge use predict that prey from populations having lower predation pressure have shortened flight initiation distance (FID; distance between a predator and a prey when escape begins), reduced distance fled and tendency to enter refuge, and shortened hiding time before emerging from refuge. By ourselves simulating approaching predators, we tested these predictions for two populations of the Balearic lizard, Podarcis lilfordi (Müller, 1927), on the islets of Rei (higher predation pressure) and Aire (lower) adjacent to Menorca. FID, distance fled, and hiding time were shorter and probability of entering refuge was lower on Aire than on Rei, confirming all predictions. All effect sizes were large, indicating major differences in antipredatory behavior between islets. These findings are consistent with data for other lizards on FID and limited data on distance fled and refuge entry. The effect of predation pressure on hiding time is a novel finding. Our results and those of previous studies suggest that relaxation of predation pressure leads to reduced natural selection for maintenance of antipredatory behavior at all stages of predator–prey interactions over a relatively short time span.

Tissue section lifting for electron microscopy

1978 ◽  
Vol 36 (2) ◽  
pp. 86-87
Author(s):  
Adrian F. van Dellen
Keyword(s):  
Infectious Disease ◽  
Electron Microscopy ◽  
Tissue Culture ◽  
Organ System ◽  
Surrounding Tissue ◽  
Paraffin Sections ◽  
Surface Areas ◽  
Specific Determination ◽  
High Degree ◽  
Accuracy And Repeatability

The morphologic pathologist may require information on the ultrastructure of a non-specific lesion seen under the light microscope before he can make a specific determination. Such lesions, when caused by infectious disease agents, may be sparsely distributed in any organ system. Tissue culture systems, too, may only have widely dispersed foci suitable for ultrastructural study. In these situations, when only a few, small foci in large tissue areas are useful for electron microscopy, it is advantageous to employ a methodology which rapidly selects a single tissue focus that is expected to yield beneficial ultrastructural data from amongst the surrounding tissue. This is in essence what "LIFTING" accomplishes. We have developed LIFTING to a high degree of accuracy and repeatability utilizing the Microlift (Fig 1), and have successfully applied it to tissue culture monolayers, histologic paraffin sections, and tissue blocks with large surface areas that had been initially fixed for either light or electron microscopy.

Electron Microscopy in Molecular Biology

1967 ◽  
Vol 25 ◽  
pp. 2-3
Author(s):  
Cecil E. Hall
Keyword(s):  
Electron Microscopy ◽  
Molecular Biology ◽  
Noise Level ◽  
Molecular Structures ◽  
Material Structure ◽  
The Arts ◽  
Shadow Casting ◽  
Electron Image ◽  
High Degree ◽  
Very High

The visualization of organic macromolecules such as proteins, nucleic acids, viruses and virus components has reached its high degree of effectiveness owing to refinements and reliability of instruments and to the invention of methods for enhancing the structure of these materials within the electron image. The latter techniques have been most important because what can be seen depends upon the molecular and atomic character of the object as modified which is rarely evident in the pristine material. Structure may thus be displayed by the arts of positive and negative staining, shadow casting, replication and other techniques. Enhancement of contrast, which delineates bounds of isolated macromolecules has been effected progressively over the years as illustrated in Figs. 1, 2, 3 and 4 by these methods. We now look to the future wondering what other visions are waiting to be seen. The instrument designers will need to exact from the arts of fabrication the performance that theory has prescribed as well as methods for phase and interference contrast with explorations of the potentialities of very high and very low voltages. Chemistry must play an increasingly important part in future progress by providing specific stain molecules of high visibility, substrates of vanishing “noise” level and means for preservation of molecular structures that usually exist in a solvated condition.

A High Angle, Double Tilting Cold Stage for the AEI EM7

1974 ◽  
Vol 32 ◽  
pp. 450-451
Author(s):  
P.R. Swann ◽  
A.E. Lloyd
Keyword(s):  
Habit Plane ◽  
Temperature Control ◽  
Tilt Angle ◽  
Cooling System ◽  
Thermal Drift ◽  
High Angle ◽  
Cold Stage ◽  
High Degree ◽  
Better Than

Figure 1 shows the design of a specimen stage used for the in situ observation of phase transformations in the temperature range between ambient and −160°C. The design has the following features a high degree of specimen stability during tilting linear tilt actuation about two orthogonal axes for accurate control of tilt angle read-out high angle tilt range for stereo work and habit plane determination simple, robust construction temperature control of better than ±0.5°C minimum thermal drift and transmission of vibration from the cooling system.

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