The value of a mouthful: Flight initiation distance as an opportunity cost

Flight initiation distance of animals when approached by a potential predator reflects the risk that an individual is willing to take when the individual has to gauge the value of staying put relative to the cost of flight. I predicted that this cost–benefit balance would depend on the opportunity cost of fleeing. This opportunity cost can be estimated as the difference in flight initiation distance (FID) between an individual engaged in eating rather than just loafing. I estimated FID of 55 species of birds when approached by a human whilst eating or loafing. There was highly significant variation in difference in FID between these two situations amongst species. Species eating mobile food that is difficult to catch showed little difference in FID between the two situations, whilst species eating immobile food such as seeds had longer FID when eating than when loafing. This difference was fully attributed to differences in relative eye size, because species that had longer FIDs when foraging rather than loafing had small eyes, whilst species with long FIDs when loafing rather than foraging had large eyes. Species with long FIDs, when foraging compared to loafing, had low adult annual survival rates and vice versa. This effect was independent of whether mobile or immobile food was consumed. These findings suggest that individuals of different species adjust their FID to the probability of adult survival and also that differences in visual acuity among species as reflected by eye size linked to differences in food mobility affect the opportunity cost of risk taking

A new species of Peckia (Diptera: Sarcophagidae) from Costa Rica : with a note on P. pexata (Wulp)

A new species of Peckia Robineau-Desvoidy is described from the coastal dry forest of Guanacaste Province, Costa Rica, viz., Pechia glyphis sp.n., and a key to the ten species of Peckia known from the area is provided. A lectotype is designated for Pechia pexata (Wulp, 1895) and intraspecific variation in male leg setosity and in the morphology of male terminalia are documented

A Counterexample to a Conjecture about Positive Scalar Curvature

Conjecture 1 of Stanley Chang: "Positive scalar curvature of totally nonspin manifolds" asserts that a closed smooth manifold M with non-spin universal covering admits a metric of positive scalar curvature if and only if a certain homological condition is satisfied. We present a counterexample to this conjecture, based on the counterexample to the unstable Gromov-Lawson-Rosenberg conjecture given in Schick: "A counterexample to the (unstable) Gromov-Lawson-Rosenberg conjecture".Comment: v1: 4 pages, AMS-LaTeX; v2: small changes in presentation, typos corrected, v3: comment added, to appear in Proc AM

Non-Rectangular Convolutions and (Sub-)Cadences with Three Elements

The discrete acyclic convolution computes the 2n-1 sums sum_{i+j=k; (i,j) in [0,1,2,...,n-1]^2} (a_i b_j) in O(n log n) time. By using suitable offsets and setting some of the variables to zero, this method provides a tool to calculate all non-zero sums sum_{i+j=k; (i,j) in (P cap Z^2)} (a_i b_j) in a rectangle P with perimeter p in O(p log p) time. This paper extends this geometric interpretation in order to allow arbitrary convex polygons P with k vertices and perimeter p. Also, this extended algorithm only needs O(k + p(log p)^2 log k) time. Additionally, this paper presents fast algorithms for counting sub-cadences and cadences with 3 elements using this extended method

Concerns about the use of ecosystem services as a tool for nature conservation: From misleading concepts to providing a “price” for nature, but not a “value”

1. By definition, ecosystem services (ES) are the “benefits that people obtain from ecosystems”, and this paradigm has been increasingly used in recent decades in ecological planning, for policy development and environmental management.2. In this short commentary, we highlight the main criticisms suggested by several scientists against the currently used and abused ecosystem services (ES) approach.3. We underline how this concept needs a more accurate scientific assessment and theoretical development, repeating that one of the most critical concerns is that this paradigm assigns a “price”, but not a “value” to nature.4. We also discuss different theoretical concerns, as for example the replacement of natural “resource” by “service” promoted by the ES paradigm thereby changing the implications of such assessments. Conserving resources is essential for survival of several organisms, while conservation of a “service” is mainly related to the human species.5. Finally, we warn against the mechanism of ‘crowding out’ behind the ES approach, which replaces intrinsic motivations (nature) against extrinsic ones (benefits), highlighting that people do not need to attach different values to ecosystems (monetary, cultural, aesthetic, etc.) to understand the value of nature

A new species of Boettcheria from Guatemala (Diptera: Sarcophagidae)

Boettcheria styx new species is described from Guatemala, and a key is provided to separate it from B. maerens (Townsend). A list is given of Central American species of Boettcheria with references to figures of their genitalia

A new ventrops (Diptera: Rhinophoridae) from Ethiopia

A new species of the Afrotropical endemic rhinophorid genus Ventrops is described, illustrated and compared with congeners

Liquidity Effects of Changes in a Pan-European Stock Index

Adding or deleting a security to or from an index can influence the share price considerably. A possible explanation that has been brought forward in the literature is the liquidity hypothesis according to which an increase in liquidity after an addition is responsible for the observed rise in value. In the following paper, we examine liquidity effects on securities that have been added to or deleted from the pan- European index STOXX 50 between 1998 and 2003, using bid-ask spreads as indicators for liquidity. While there is a medium term price effect, bid-ask spreads do not change significantly due to the index addition or deletion. Regression analysis shows that the explanatory power of bid- ask spreads for the observed price effect is negligible. As a consequence of our empirical findings, the liquidity hypothesis has to be rejected for the STOXX 50. This result, however, does not appear particularly surprising, as the STOXX 50 is composed of already highly liquid securities whose trading liquidity appears not to depend on membership in an international index. A possible explanation for the rejection of the liquidity hypothesis is that the applicability of the liquidity hypothesis hinges on the liquidity class of the stocks concerned before being added. Marginal increases of liquidity due to an index addition might decline with larger initial liquidity of the stocks added. Subsequent studies could focus on the particular shape of this 'liquidity curve' of stocks.Pan-European stock index, index effect, STOXX, liquidity, price effect

Cost-saving or Cost-enhancing Mergers: the Impact of the Distribution of Roles in Oligopoly

Horizontal Merger, Efficiency gains, Efficiency losses, Stackelberg oligopoly, Market power