Origin of the Type III Functional Response

In this chapter I review the many ways that functional responses may show a sigmoidal shape rather than the simpler asymptotic shape. I break down the potential for prey dependence of the space clearance rate through effects on each of the component mechanisms. Given the emergent nature of the functional response, type III curves can arise through density dependence of the probability of successful capture, prey detectability, and predator–prey encounter rates. Given the variety of mechanisms, it may be possible that there are really multiple types of type III curve. I also raise some concerns with the standard type III model and offer an alternative model that gets around these problems.

Discriminating predation attempt outcomes during natural foraging using the post-buzz pause in Japanese large-footed bat Myotis macrodactylus

Bats emit a series of echolocation calls with an increasing repetition rate (the terminal buzz), when attempting to capture prey. This is often used as an acoustic indicator of prey-capture attempts. However, because it is directly linked to foraging efficiency, predation success is a more useful measure than predation attempts in ecological research. The characteristics of echolocation calls that consistently signify predation success across different situations have not been identified. Due to additional influencing factors, identification of these characteristics is particularly challenging for wild bats foraging in their natural environment compared to those in flight chambers. This study documented the natural foraging behavior of wild Japanese large-footed bat Myotis macrodactylus using synchronized acoustic and video recordings. From the video recordings, we could assign 137 attacks to three outcome categories: prey captured (51.8%), prey dropped (29.2%), and failed attempt (19%). Based on previous indications from laboratory studies that the length of the silent interval following the terminal buzz (post-buzz pause) might reflect the prey capture outcome, we compared post-buzz pause durations among categories of attack outcomes. The post-buzz pause was longest in the case of successful capture, suggesting that the length of the post-buzz pause is a useful acoustic indicator of predation success during natural foraging in M. macrodactylus. Our finding will advance the study of bat foraging behavior using acoustic data, including estimations of foraging efficiency and analyses of feeding habitat quality.Summary statementWe investigated the natural foraging behavior of wild Myotis macrodactylus and found that the length of the post-buzz pause is a useful acoustic indicator of predation success.

Late-stage C–H thiolation via sulfonium salts using β-sulfinylesters as the versatile sulfur source

Organic sulfides form the core scaffold of a wide range of pharmaceuticals, natural products, and materials, and serve as key intermediates in synthesis. Prior methods to organic sulfides require the use of transition metal (TM) catalysts, prefunctionalized or chelating group-containing substrates, and elevated reaction temperatures. A general TM-free C–H thiolation protocol using readily accessible sulfur source is highly desirable. Herein, we disclose a direct C(sp)–, C(sp2)–, and C(sp3)–H thiolation reaction using β-sulfinylesters as the versatile sulfur source. The key step of this protocol is chemoselective C–S bond cleavage of the sulfonium salts that is in situ formed from the corresponding (hetero)arenes, alkenes, alkynes, and 1,3-dicarboxyl compounds with β-sulfinylesters. The successful capture of acrylate byproduct supports a retro-Michael reaction mechanism. This method is expected to be used widely because of several advantageous aspects including TM-free, mild reaction conditions, and broad substrate scope including drug molecules.

The storm of the Troyan Pass on December, 26, 1877 and the Bulgarians: Historiographic myths and the reality

The article focusses on the successful capture on December 26, 1877 of the Turkish fortification “Eagle’s Nest” or “Kurt Hisar” (in Turkish “The Wolf Fortress”), built on top of the hard-to-reach Troyan Pass, leaded by the Troyan detachment under the command of Lieutenant General P. P. Kartsov. A scrupulous study of the complex of published sources reveals a more complex picture of interactions between Russians and Bulgarians than the one presented in the Marxist historiography. The promises the Bulgarian population has made to provide significant assistance to the Russians (to provide 200 packhorses, 400 workers, etc.) were presented by Marxist historians as a fait accompli, but in fact, even for a high fee, the Bulgarians did not fulfill their obligations responsibly and in full according to the agreement reached. Hopes for real assistance from the Bulgarian armed units during the battle of the Troyan detachment with the Turkish garrison turned out to be in vain: with the exception of a few brave men, the overwhelming majority of the Chetniks stayed in the rear. Kartsov, as a pleasant exception among the Bulgarians, named only two persons who rendered invaluable services: Archimandrite Makari, the abbot of the Troyan Assumption Monastery, and George, the foreman of the Troyan district. Gratefully mentioned should be those Bulgarian guides that in the most difficult conditions, did not refuse to lead Russian troops along the snow-covered paths of the harsh Balkans, as well as those Bulgarians who, together with Russian soldiers, harnessed to raise cannons to the Troyan steep.

Functional–morphological analyses of the delicate snap-traps of the aquatic carnivorous waterwheel plant (Aldrovanda vesiculosa) with 2D and 3D imaging techniques

Background and Aims The endangered aquatic carnivorous waterwheel plant (Aldrovanda vesiculosa) catches prey with 3–5-mm-long underwater snap-traps. Trapping lasts 10–20 ms, which is 10-fold faster than in its famous sister, the terrestrial Venus flytrap (Dionaea muscipula). After successful capture, the trap narrows further and forms a ‘stomach’ for the digestion of prey, the so-called ‘sickle-shaped cavity’. To date, knowledge is very scarce regarding the deformation process during narrowing and consequent functional morphology of the trap. Methods We performed comparative analyses of virtual 3D histology using computed tomography (CT) and conventional 2D histology. For 3D histology we established a contrasting agent-based preparation protocol tailored for delicate underwater plant tissues. Key Results Our analyses reveal new structural insights into the adaptive architecture of the complex A. vesiculosa snap-trap. In particular, we discuss in detail the arrangement of sensitive trigger hairs inside the trap and present actual 3D representations of traps with prey. In addition, we provide trap volume calculations at different narrowing stages. Furthermore, the motile zone close to the trap midrib, which is thought to promote not only the fast trap closure by hydraulics but also the subsequent trap narrowing and trap reopening, is described and discussed for the first time in its entirety. Conclusions Our research contributes to the understanding of a complex, fast and reversible underwater plant movement and supplements preparation protocols for CT analyses of other non-lignified and sensitive plant structures.

A game of patience between predator and prey: waiting for opponent’s action determines successful capture or escape

When predator and prey animals face each other, preemptive actions by both sides are considered to mediate successful capture or escape. However, in spite of the general presumption, some animals, such as predatory snakes and their frog prey, occasionally remain motionless or move slowly for a while before striking or escaping, respectively. To clarify the possible advantages of this behaviour, we examined interactions between Japanese Four-lined Ratsnakes (Elaphe quadrivirgata (H. Boie, 1826)) and Black-spotted Pond Frogs (Pelophylax nigromaculatus (Hallowell, 1861)), focusing especially on kinematic features of strike behaviour of snakes and flight behaviour of frogs in close quarters. Staged encounter experiments and field observations revealed that counteractions against an opponent’s preemptive actions are effective for both snakes and frogs until a certain distance because they are hardly able to change their trajectories once they initiate strike or escape behaviours. Snakes and frogs also appropriately switched their behaviour from waiting for the opponent’s action to taking preemptive action at this threshold distance. These results suggested the occurrence of a game of patience between snakes and frogs in which they wait for the opponent’s action to achieve effective countermeasures. Our study provides new insights for predicting optimal decision-making by predators and prey and will contribute to a better understanding of their strategies.