Une nouvelle espèce d'Euglène,Euglena Penardii

Sans résumé     

Cooperation, conflict, and crèching behavior in goldeneye ducks

Crèching behavior, or brood amalgamation, results in offspring being reared by adults other than their genetic parents. Although a variety of hypotheses have been proposed to explain this behavior, most assume either that brood amalgamation is accidental (i.e., nonselected) or that adoption of young is selected for because of social benefits to the young and/or adopting parents. We propose, instead, that brood amalgamation is a function of two separate processes: brood desertion and brood adoption. To examine brood desertion, we develop a graphic model to predict when parents should abandon their young and we test this model experimentally for the Barrow's goldeneye (Bucephala islandica). As predicted, females deserted their offspring when the size of the brood was experimentally reduced. Brood adoption occurred when deserted ducklings joined other broods. However, the success of ducklings in doing so was strongly dependent on the availability of potential host broods and on the age of the recipient broods. Foreign ducklings were readily accepted into young broods (<10 d old) but invariably were rejected from old broods. We could detect no benefits or costs of brood adoption to the host females, contrary to the expectations of a social benefit hypothesis. Our experiments indicate that Crèching behavior is driven by selection on adults to abandon their brood when the benefits of continued investment are outweighed by the reduction in future reproduction and selection on deserted ducklings to join other broods to obtain parental care. Rather than a form of cooperative brood care, Crèching in goldeneyes is perhaps best considered as a form of reproductive parasitism, entailing parent-offspring conflict over brood desertion and intergenerational conflict over adoption of abandoned young.     

Une nouvelle espèce du genre Bohlinia (Mammalia,Giraffidae) du Miocène supérieur de Toros-Menalla,Tchad

New Giraffidae specimens discovered from the Late Miocene fossiliferous sector of Toros-Menalla (northern Chad) are described. These specimens are assigned to Bohlinia, a genus known so far only in some Late Miocene localities of Eurasia. This is the first occurrence of the genus in Africa. Analysis of the material allows us to describe a new species of giraffid, Bohlinia adoumi n. sp., probably close to the Eurasian forms.     

A partial hominoid humerus from the middle miocene of Castell de Barberà (Vallès-Penedès Basin, Catalonia, Spain)

The hominoid right partial humerus IPS4334, from the middle Miocene (MN 8) of Castell de Barberà (Vallès-Penedès Basin, Catalonia, Spain), is described. It preserves the mid-distal portion of the shaft until the proximal margins of the radial and coronoid fossae, as well as the proximal portion of the olecranon fossa; the capitulum, the trochlea and the two epicondyles are missing. Although morphological comparisons are restricted, available evidence indicates that IPS4334 is more derived towards the modern hominoid condition than the Klein Hadersdorf specimen attributed to Griphopithecus (ca. 13-14 Ma), thus being most similar (except for its larger size and greater robusticity) to the presumably juvenile specimen of Dryopithecus fontani from Saint Gaudens in France (ca. 11-12 Ma). On the basis of shaft measurements and allometric regressions derived for extant hominoids, a body mass estimate around 50 kg is derived for IPS4334. Morphological similarities with the Saint Gaudens specimen, together with the large body mass estimate, suggest a tentative attribution of IPS4334 to cf. D. fontani, which is the largest hominoid taxon so far recorded from the Vallès-Penedès Basin. The larger size and higher robusticity of IPS4334 as compared to the Saint Gaudens specimen might be explained by the juvenile status of the latter and/or sexual dimorphism. When both specimens are considered together with a partial femur from Abocador de Can Mata, D. fontani emerges as a less suspensory ape than the late Miocene Hispanopithecus, the locomotor repertoire of the former emphasizing climbing, but still displaying a significant quadrupedal component.     

Les Cases de la Valenciana,a new early Miocene small-mammal locality from the Vallès-Penedès Basin (Catalonia,Spain)

Abstract

The Valles-Penedes Basin (Catalonia, Spain) is classical area for the study of Miocene land mammal faunas. Nevertheless, the early Miocene part of the record has deserved little attention as compared to younger intervals. Most notably, the small mammals of this age have not been described in detail, consequently hampering the correlation of the Valles-Penedes record with other chronological schemes. In this work we describe the rich and diverse small mammal fauna from Les Cases de la Valenciana site (Gelida, Alt Penedès) which includes marsupials, eulipotyphlans, lagomorphs and rodents. On the basis of the presence of the cricetids Megacricetodon and Democricetodon this site is correlated with European Neogene zone MN4, yielding an age of 17–16 Ma. However, the rodent assemblage is comparable to that of chronologically close localities of the Calatayud-Montalbán Basin (Aragon, Spain), indicating that the same biochronological scheme can be applied to both areas. In this way, the coexistence of the eomyids Ligerimys ellipticus and Ligerimys florancei coupled with the presence of Megacricetodon primitivus indicates a correlation with local biozone Ca of the Calatayud-Montalban Basin, ranging from 16.3 to 16 Ma. Finally, the correlation of other early Miocene sites of the Valles-Penedes Basin is discussed and refined.     

A new pliopithecid genus (primates: Pliopithecoidea) from Castell de Barberà (Vallès-Penedès Basin, Catalonia, Spain)

Barberapithecus huerzeleri gen. et sp. nov. (Primates, Pliopithecidae) is erected on the basis of material from Castell de Barberà (Middle to Late Miocene, ca. 11.2-10.5 Ma), in the Vallès-Penedès Basin (Catalonia, Spain), including: 15 teeth (representing most of the permanent dentition) from a single female individual (holotype); an isolated P/3 (paratype); and a male C1/ (referred to the hypodigm). Previously, this material had been only partially figured and described, being attributed to Pliopithecus or to a new taxon with possible crouzeliine affinities. The erection of a new genus is justified by several autapomorphic features, such as markedly buccolingually compressed and mesiodistally elongated C1/, extremely buccolingually compressed, and mesiodistally oriented C/1 main cusp, P/4 with a large trigonid subequal to the talonid, very large distal foveae on the M/1 and especially the M/2, and lower molars with a quadrangular central fovea and a mesially situated entoconid. These features are associated with a set of crouzeliine synapomorphies, such as buccolingually compressed and peripheralized cusps, well-developed crests, large and well-defined occlusal foveae, upper molars with long preprotocrista, short hypoparacrista, somewhat distally situated protocone and short distal fovea, distinct P/3 metaconid, well-developed P/4 premetacristid, and relatively narrow lower molars with a reduced entoconid. Although more primitive, Barberapithecus resembles Anapithecus in some derived features. Both taxa are included into a new tribe (Anapithecini), together with other crouzeliines except Plesiopliopithecus (tribe Crouzeliini). The retention of primitive, pliopithecine-like features in Barberapithecus suggests that anapithecins might have evolved from a Pliopithecus ancestor, so that as currently conceived the Crouzeliinae might be polyphyletic.     

Synthèse biostratigraphique du plio-pléistocène de Guadix-Baza (Province de Granada,Sud-Est de l'Espagne)

In the Guadix-Baza basin, a continental sequence 0214 ranging from the Upper Miocene (Upper Turolian) to the Middle Pleistocene (Cromerian) has been established. An essay of biozonation by means of the Rodent succession is proposed, based on the following biozones: Trilophomys castroi, Mimomys occitanus, Mimomys cappetai, Mimomys cf. reidi, Mimomys ostramosensis, Allophaiomys pliocaenicus, Mimomys savini and Arvicola cantiana.     

Une nouvelle espèce d'Apodemus (Rodentia,Mammalia)du Pliocène de la dépression de Guadix-Baza (Grenade,Espagne)

This paper describes a new species of Apodemus,A. agustii, a Middle Pliocene Muridae from the Guadix-Baza basin. Its morphology is far from that postulated as more frequent in Apodemus: its molars crowns are relatively high: there is no connection between t6 and t9 in M¹ and M². Taking in account this and its age, it is placed in an evolutionary branch, convergent with “Rhagapodemus” morphotype.     

Reproductibilité interobservateur d'un tympanomètre portatif,le MicroTymp.

OBJECTIVE: To determine the interobserver reliability of tympanograms obtained with the MicroTymp, a portable tympanometer. SETTING: Family medicine teaching unit in a tertiary care hospital. PATIENTS: Thirty-three patients who presented to the ear, nose and throat clinic in August 1990 for an ear problem. INTERVENTION: Three residents in family medicine independently attempted to record with the MicroTymp one tympanogram for the 66 ears. We excluded the results for seven ears for which tympanograms could not be obtained. MAIN OUTCOME MEASURE: Using objective criteria, two family physicians and two residents in family medicine independently classified the 177 tympanograms into five categories (normal, possible effusion, possible perforation, possible tympano-ossicular dysfunction and unclassifiable). Reliability was estimated by means of the kappa (kappa) coefficient on 161 tympanograms from 59 ears for which the interpretation of the three tympanograms agreed. MAIN RESULTS: The interpretation of the three tympanograms agreed for 34 of the 59 ears (0.58) (kappa = 0.52, 95% confidence limits 0.45 and 0.59). There was no significant difference in interobserver reliability between pairs of observers or between symptomatic and asymptomatic ears. CONCLUSIONS: The interobserver reliability of the MicroTymp is moderate. The tympanograms obtained with the instrument should be interpreted in the context of the clinical findings.     

Direct and indirect regulation of derrière,a Xenopus mesoderm-inducing factor,by VegT

One candidate for an endogenous mesoderm-inducing factor in Xenopus is derrière, a member of the TGFbeta family closely related to Vg1. In this paper we first show that derrière is able to exert long-range effects in the early Xenopus embryo, reinforcing the view that it functions as a secreted factor required for proper formation of posterior structures. Analysis of the derrière promoter shows that expression of the gene is controlled through a complex inductive network involving VegT and TGFbeta-related molecules and also, perhaps, FGF family members. The work confirms that derrière plays an important role in mesoderm formation and it illustrates the complex regulation to which inducing factors are subject.