Different singing styles in mated and unmated Reed Buntings Emberiza schoeniclus

Ewin described two singing styles, "rapid" and "slow", in the Reed Bunting Emberiza schoeniclus. My research has demonstrated that the prevalence of song styles is related to male mating status. Songs of mated and unmated males differed in the interval structure, number of syllables per song, number of frequency modulations per syllable and number of introductory syllables. Since both singing styles are uttered at the same intensity, it is not likely that they are parts of a continuous range and it is justified to treat them as two different song categories. After losing their mate, males sang like unpaired males and therefore a learning effect can be excluded. Both singing styles were directed to females, the slow one probably only to the mate. The use of these singing styles as a means of territory or mate defence cannot be excluded, but, if so used, it would seem to be of minor significance.     

Electrical Polarity and Cellular Differentiation in Meroistic Ovaries

SYNOPSIS. In the oocyte-nurse cell syncytium of meroistic insectovaries a gradient in electrical potential is shown to drivea micro-injected basic protein (fluorescein-labeled lysozyme)and its methylcarboxylated, acidic derivative in opposite directions.In the polytrophic Cecropia ovary the electrophoretic effectis greatest in the intercellular bridges, while in the telotrophicRhodnius ovary it is greatest within the nurse chamber. We speculatethat in both systems the potential gradient prevents the freediffusion of cell cycle and differentiative control proteins,while at the same time reinforcing the transport of acidic precursorstoward the ooplasm. Because of its apparent ability to affectthe distribution of polyions that govern nuclear function, electricalpolarity can also be envisioned to have a more general rolein the control of differentiation. The possibility is consideredthat it serves as a relay mechanism for the non-diffusing determinantthat is already known to govern the differentiation of oocytesfrom nurse cells.     

Performance of a new dynamic model for predicting diurnal time courses of stomatal conductance at the leaf level

Under natural conditions, plants are subjected to continuous changes of irradiance that drive variations of stomatal conductance to water vapour (g_s). We propose a dynamic model to predict the temporal response of g_s at the leaf level using an asymmetric sigmoid function with a unique parameter describing time constants for increasing and decreasing g_s. The model parameters were adjusted to observed data using Approximate Bayesian Computation. We tested the model performance for (1) instant changes of irradiance; or (2) continuous and controlled variations of irradiance simulating diurnal time courses. Compared with the two mostly used steady‐state models, our dynamic model described daily time courses of g_s with a higher accuracy. In particular, it was able to describe the hysteresis of g_s responses to increasing/decreasing irradiance and the resulting rapid variations of intrinsic water‐use efficiency. Compared to the mechanistic model of temporal responses of g_s by Kirschbaum, Gross & Pearcy, for which time constants were estimated with a large variance, our model estimated time constants with a higher precision. It is expected to improve predictions of water loss and water‐use efficiency in higher scale models by using a small number of parameters.     

The Effects of One-Off Ivory Sales on Elephant Mortality

ABSTRACT We revisited the debate about whether the 1999 one-off sale of ivory promoted elephant (Loxodonta africana) poaching in Africa. Complementing earlier work based on ivory seizure data, we considered data on elephant mortality in Zimbabwe and Kenya. Our findings present a mixed picture. At the local level there was some evidence that the one-off sale resulted in extra elephant killing, but this effect was relatively small (and probably short-lived). Although the data were too scanty to draw strong conclusions, decision-making about elephant management and the ivory trade has to continue and will necessarily be based on imperfect information for a long time to come. Our findings suggest that further experimenting with one-off sales may be beneficial from a conservation and development perspective.     

Molecules,morphology and Mimeoma scarabs: evolutionary and taxonomic implications for a palm‐associated scarab group

Cyclocephaline scarabs, the second largest tribe of rhinoceros beetles, are important pollinators of early‐diverging angiosperm families in the tropics. The evolutionary history of cyclocephaline genera is poorly resolved and several genera are thought to be nonmonophyletic. We assess the monophyly of Mimeoma Casey, a group of Neotropical palm‐feeding scarabs, and its relationship to Cyclocephala with a phylogenetic analysis of 2899 bp of DNA sequence data and 18 morphological characters. All five species of Mimeoma were included in analyses along with species of Cyclocephala Dejean, Dyscinetus Harold and Tomarus Erichson as outgroup taxa. Nearly complete 28S, 12S and CO1 data were collected from 26 of 29 specimens, of which 16 samples were pinned, museum specimens. 28S data strongly support a nonmonophyletic Mimeoma; mitochondrial data (CO1 and 12S) suggest that Mimeoma species are nested within an apical clade of other Cyclocephala species; combined molecular and morphological data identify two strongly supported clades of Mimeoma species but do not support their sister relationship. Combined data show that Mimeoma species are nested within Cyclocephala, thus rendering Cyclocephala paraphyletic. Mimeoma is synonymized within Cyclocephala resulting in the following new combinations: Cyclocephala acuta Arrow n.comb ., Cyclocephala englemani (Ratcliffe) n.comb ., Cyclocephala maculata Burmeister n.comb ., Cyclocephala nigra (Endrödi) n.comb . and Cyclocephala signatoides Höhne n.comb . Our results demonstrate that pinned, museum specimens can be used to obtain DNA sequence data (particularly high‐copy gene regions) for evolutionary studies, and provide the first empirical support that host‐plant associations within cyclocephaline scarab clades are conserved at the plant family‐level.