THE MOLLUSCAN EPIFAUNA OF THE ALGA HALOPTERIS SCOPARIA IN SOUTHERN SPAIN AS A BIOINDICATOR OF COASTAL ENVIRONMENTAL CONDITIONS

The effects of certain environmental factors on spatial variationof the mollusc community associated with the alga Halopteris scopariain Algeciras Bay (southern Spain), located in the Strait ofGibraltar, are studied. Environmental gradients from the exterior tothe interior of the bay have been detected, related above allto water movements, solids in suspension, organic content ofsediments, and structural complexity of plants. These gradientsare seen as differences in the composition of the mollusc communitiesof the outer zones (Isla de Las Palomas, San Garcma, and Cucareo)and inner ones (Guadarranque and Crinavis). Although the conditionsof the inner zone restrict the growth of some groups such ascrustaceans and polychaetes, mollusc populations have developedwell there in both number and diversity. Species are found exclusivelyat the exterior of the Bay (include Cingula amabilis, Pisinnaglabrata, and Nodulus contortus) and for the interior (Alvania montagui,Alvania rudis, and Rissoa similis), the latter being the mostdiscriminating between the two major zones of the bay. The environmentalparameters having the greatest effect on the molluscs associatedwith Halopteris scoparia are water movement, the morphologicalcharacteristics of the substrate, and most importantly the availabilityof food. (Received 27 July 1999; accepted 5 January 2000)     

REPRODUCTIVE COST,AGE-SPECIFIC SURVIVAL AND A COMPARISON OF THE REPRODUCTIVE STRATEGY IN TWO EUROPEAN TITS (GENUS PARUS)

Theoretical analyses of optimal reproductive rates usually assume a trade-off between offspring production and parental survival. This study verified a survival cost for willow tit males; nonbreeding males survived better than males attending a brood. Theory also predicts a smaller clutch size in birds that are less successful in transforming reproductive investments into mature offspring. As predicted, we found that crested tits, suffering a higher nest predation rate, laid smaller clutches than willow tits. The generally lower survival rate of willow tit adults may largely be attributed to their higher reproductive commitment (larger willow tit clutch size), because no significant interspecific survival difference remained between nonbreeding males. Finally, in willow tits we found a positive correlation between average clutch size and juvenile survival rate (density-dependent) the ensuing year, suggesting that willow tits may adjust clutch size in response to changing survival prospects for their young by using the breeding density as a cue.     

THE DEMOSPONGE GENUS LEPTOMITUS and A NEW SPECIES FROM THE MIDDLE CAMBRIAN OF SPAIN

Abstract:  Forty-five specimens of Leptomitus conicus sp. nov. have been collected from the base of the Murero Formation (Caesaraugustan, Middle Cambrian) in the Murero area of Zaragoza, north-east Spain. The new species is a small obconical sponge, which has coarse oxeas forming parallel rods that run the whole length of the specimens in the manner typical of the genus. The biostratigraphy and facies of the levels with Leptomitus conicus have been analysed. Palaeoecological information derived from associated trilobites, brachiopods and ichnofossils shows that L. conicus lived in a soft substrate of a sublittoral environment of low to low/moderate energy. According to established Cambrian palaeogeographical reconstructions, a tropical distribution is inferred for the genus Leptomitus . Based on body shape, wall structure and stratigraphical distribution, a phylogenetic tree of the various Leptomitus species is proposed, with a central stock of simple cylindrical sponges branching out to other morphs.     

陕西宁强原始锥石类五辐对称新属种的发现

陕西宁强宽川铺地区灯影组宽川铺段的原始锥石类Carinachitids中,新发现了五辐对称新属种--五分宁强锥石(新属、新种)Pentaconularia ningqiangensis gen.et sp.nov..本文对这一新属种进行了描记.结合前人发现的两辐对称、三辐对称、四辐对称的Carinachitids系列标...     

中国全缘孔菌属及新种

本文报道产于中国东北长白山的多孔菌科(Polyporaceae)全缘孔菌属(Haploporus)一新种,即苦味全缘孔菌(H.amarus zeng et Bai)。作者在文中还对全缘孔菌属及其模式种的建立,命名和属的概念进行了讨论。模式标本存于东北师范大学生物系植物标本室(HBNNu)。     

ADAPTATION IN THE GENUS PHYLLOSCOPUS

The paper describes variation among species of the genus Phylloscopus in weight, relative wing-, tail-, tarsus-, and bill-length, tail/wing ratio and degree of roundness of the wing, wing formula, emargination, and plumage colour. This variation is compared with differences in niche preference within the genus, and relationships between niche, feeding strategies, and morphology are suggested. It is concluded that evolution within the genus has taken place mainly through the development of different feeding strategies, to suit the structural properties of different niches, without altering the range of size of the prey. The genus Sylvia is treated briefly in order to provide comparison, and other genera of Sylviinae are discussed where parallel adaptation seems likely.