Why Do Males of the Spider Pisaura mirabilis Wrap Their Nuptial Gifts in Silk: Female Preference or Male Control?

Males of the spider Pisaura mirabilis present a nuptial prey gift to the female during courtship as a mating effort. The gift is usually round and wrapped in white silk. It was suggested that the wrapped gift functions as a sensory trap by mimicking the female's eggsac implying that males exploit the female maternal care instinct and not her foraging motivation in a sexual context. The shape of the gift (round) and appearance (white) should then increase female acceptance of males. We tested these predictions experimentally and found that neither gift shape (round or oblong) nor silk wrapping (wrapped or unwrapped) facilitated female acceptance, in contrast unwrapped gifts were accepted faster than wrapped ones. Instead, we found that silk wrapping benefited the males because it significantly decreased the risk of females stealing the gift without copulation and consequently directly increased male mating success. Large oblong gifts were difficult for males to handle during copulation, resulting in shorter copulations for oblong vs. round gifts. Thus, round gifts were not preferred by the females but were beneficial to the males. Our results indicate two adaptive benefits to males of wrapping the nuptial gift: to reduce the risk of losing the gift to females without copulation, and make it possible to reshape an oblong prey into a round gift that facilitates the male's access to the female's genitalia. Our results suggest that the male gift wrapping trait may be selected though sexual conflict over remating rate.     

Révision du genre Perrindema Lacroix 1997 (Insecta : Coleoptera : Scarabaeoidea : Melolonthidae : Pachydeminae)

La synonymie entre Perrindema Lacroix 1997, et Zanitanus Lacroix 2001, est proposée. Le genre Perrindema est révisé. Une nouvelle combinaison est établie pour Cephaloncheres lindiensis Moser 1919. Deux nouvelles espèces sont décrites du Mozambique : Perrindema quiterajoensis n. sp. et P. pembaensis n. sp. Un historique du genre est donné ainsi qu’une clé de détermination. La position systématique de ce genre au sein des Pachydemini Burmeister 1855, est discutée. La conservation de l’utilisation du nom Pachydeminae au détriment de Tanyproctinae Erichson 1847, est argumentée.     

In Memoriam: Ivan Daskalov: 1933 – 2004

Ivan Daskalov [1933–2004] was a friend who will be missed by many. Neither the quality of a man nor the concept of a friendship can be defined with words. We may only say that both will be missed.     

抗癌基因:Rb

介绍有关视网膜母细胞瘤(Retinoblastoma,简称Rb)基因研究的最新进展。已经证明Rb基因异常与某些肿瘤发生密切相关。其编码产物具有抑制细胞增殖 和细胞转化作用,可能是一个具有DNA结合活性的细胞生长负调控因子。Rb基因作为抗癌基因在肿瘤分子生物学研究中已引起人们的普遍重视。     

A Review of: “Images: A Reader”

Photographs are a ubiquitous feature of Aboriginal life in Northeastern Australia, with images of relatives being prominently displayed in most Aboriginal houses. This display of photographs is tied to a form of distributed personhood that draws on photographs to create a sense of social immediacy in the absence of close kin. This sense of immediacy also occurs in relation to photographs of the dead, giving these images a particular force for Aboriginal viewers. But further consideration of this force of photographic images suggests that they should be treated neither as things nor as aspects of persons, despite their seeming ability to manifest agency in Aboriginal life-worlds.     

Commentary: Vitamin C: Antioxidant or Pro-Oxidant In Vivo?

Ascorbic acid has a multiplicity of antioxidant properties, but it can exert pro-oxidant effects in vitro, usually by interaction with transition metal ions. It is as yet uncertain that these pro-oxidant effects have any biological relevance: some of the available data are summarized.