Higher level molecular phylogeny of darkling beetles (Coleoptera: Tenebrionidae)

Insect diversity represents about 60% of the estimated million‐and‐a‐half described eukaryotic species worldwide, yet comprehensive and well‐resolved intra‐ordinal phylogenies are still lacking for the majority of insect groups. This is the case especially for the most species‐rich insect group, the beetles (Coleoptera), a group for which less than 4% of the known species have had their DNA sequenced. In this study, we reconstruct the first higher level phylogeny based on DNA sequence data for the species‐rich darkling beetles, a family comprising at least 20 000 species. Although amongst all families of beetles Tenebrionidae ranks seventh in terms of species diversity, the lack of knowledge on the phylogeny and systematics of the group is such that its monophyly has been questioned (not to mention those of the subfamilies and tribes contained within it). We investigate the evolutionary history of Tenebrionidae using multiple phylogenetic inference methods (Bayesian inference, maximum likelihood and parsimony) to analyse a dataset consisting of eight gene fragments across 404 taxa (including 250 tenebrionid species). Although the resulting phylogenetic framework only encompasses a fraction of the known tenebrionid diversity, it provides important information on their systematics and evolution. Whatever the methods used, our results provide strong support for the monophyly of the family, and highlight the likely paraphyletic or polyphyletic nature of several important tenebrionid subfamilies and tribes, notably the polyphyletic subfamilies Diaperinae and Tenebrioninae that clearly require substantial revision in the future. Some interesting associations in several groups are also revealed by the phylogenetic analyses, such as the pairing of Aphtora Bates with Phrenapatinae. Furthermore this study advances our knowledge of the evolution of the group, providing novel insights into much‐debated theories, such as the apparent relict distribution of the tribe Elenophorini.     

Voltage Noise Changes during Monospermic and Polyspermic Fertilization of Mature Eggs of the Anuran, Rana temporaria

The electrical response of mature anuran eggs to the fertilizing sperm consists of a rapid depolarization and a decrease in resistance of the plasma membrane (fertilization potential) and serves as a fast block to polyspermy. We report here that the fertilization potential, previously thought to be the earliest electrical response of the egg, is preceded in Rana temporaria by changes in voltage noise. Voltage noise was recorded after insemination and compared in monospermic and NaI-induced polyspermic eggs. Fertilization potential in monospermic eggs arised at 1 min 45 sec to 2 min 15 sec after insemination, and that in NaI-induced polyspermic eggs did at 3 min to 3 min 30 sec after insemination. However, the increase in voltage noise was detected at the similar time (1–2 min 30 sec) after insemination in both the eggs. The duration of voltage noise increase before the fertilization potential was larger in polyspermic eggs (50–105 sec) than in monospermic eggs (10–40 sec). Polyspermic fertilization in Rana temporaria induced by NaI was checked by visualizing multiple sperm entry sites with the scanning microscope. The process of sperm entry and the development of the fertilization body are similar to those occurring with monospermic fertilization; furthermore all supernumerary sperm fuse only with the animal hemisphere of the egg. Although the physiological basis of the changes in voltage noise is unclear, these alterations appear to be the earliest electrical response to sperm yet reported.     

Puparial wax restricts passive movement of water during diapause in the flesh fly

Abstract. To determine whether the capacity of diapausing pupae of the flesh fly ( Sarcophaga crassipalpis Macquart) to absorb water from drier air than non-diapausing pupae is due to a simple passive process, we examined water flux in empty puparia. Empty puparia from both types of fly absorb and lose water passively, but those from diapause pupae do so to a lesser degree. The impervious nature of such puparia is attributed to an extra layer of cuticular wax not found in the non-diapause group.