Damage caused by mistletoe Misodendrum punctulatum Banks Ex Dc. on architecture and radial growth of Nothofagus pumilio (Poepp. et Endl.) Krasser forests of southern Chile

Parasitic plants rely completely or partially on host plant, namely holoparasitic or hemiparasitic, respectively. The effect of parasitism on host plants is not fully known. Misodendrum punctulatum (Misodendraceae) is the most common hemiparasite species in the southernmost forests of Chile and Argentina, and it has been identified as an important sanitary problem in forestry. In this study we evaluated the M. punctulatum effect on growth rates and architecture of pure Nothofagus pumilio (Nothofagaceae) forests in southern South America (52°10′S; 71°55′W). We established three plots of 30 × 30 m, and 10 cores were extracted from diameter at breast height (d.b.h. = 1.3 m) from living trees in each plot, using increment borers. Tree rings were measured, and anova was used to compare the annual growth rate of both infected and uninfected N. pumilio. The results showed that N. pumilio trees severely infected by M. punctulatum reduce growth rates in contrast with uninfected individuals (P < 0.05). Besides, trees with high‐infection levels evidenced deterioration in its architecture, showing asymmetric and suppressed canopies, according to ad hoc numerical indexes. This study provides a starting point to understand the parasite–host relationship in the Patagonian forests of southern Chile.     

A new longirostrine dyrosaurid (Crocodylomorpha,Mesoeucrocodylia) from the Paleocene of north‐eastern Colombia: biogeographic and behavioural implications for New‐World Dyrosauridae

Abstract: Fossils of dyrosaurid crocodyliforms are limited in South America, with only three previously diagnosed taxa including the short‐snouted Cerrejonisuchus improcerus from the Paleocene Cerrejón Formation of north‐eastern Colombia. Here we describe a second dyrosaurid from the Cerrejón Formation, Acherontisuchus guajiraensis gen. et sp. nov., based on three partial mandibles, maxillary fragments, teeth, and referred postcrania. The mandible has a reduced seventh alveolus and laterally depressed retroarticular process, both diagnostic characteristics of Dyrosauridae. Acherontisuchus guajiraensis is distinct among known dyrosaurids in having a unique combination of craniomandibular characteristics, and postcranial morphology that suggests it may have occupied a more placid, fluvial habitat than most known Old‐World dyrosaurids. Results from a cladistic analysis of Dyrosauridae, using 82 primarily cranial and mandibular characters, support an unresolved relationship between A. guajiraensis and a combination of New‐ and Old‐World dyrosaurids including Hyposaurus rogersii, Congosaurus bequaerti, Atlantosuchus coupatezi, Guarinisuchus munizi, Rhabdognathus keiniensis and Rhabdognathus aslerensis. Our results are consistent with an African origin for Dyrosauridae with multiple dispersals into the New World during the Late Cretaceous and a transition from marine habitats in ancestral taxa to more fluvial habitats in more derived taxa.     

Nest orientation and hatching success of Black Kites Milvus migrans in Spain

An analysis of the orientation of 182 nest sites of the Black Kite Milvus migrans in two areas in south and central Spain found that orientations toward the east were preferred. In southern Spain an analysis of the relationship between nest orientation and hatching success showed that success was lower among the nests located in non-preferred orientations, with some inter-annual variation. The tendency to orientate nests toward the east was greater among the early nesting pairs and the effect that the orientation had on the hatching success was also greater than in late nesting pairs. The data suggest that rainfall and prevailing winds were the main factors conditioning nest orientation.     

A new species of Ceratozamia (Zamiaceae) from Chiapas, Mexico

Ceratozamia zoquorum sp. nov. from the northern mountains of Chiapas, Mexico, is described and illustrated. It has affinities with C. miqueliana Wendl. from Veracruz, but differs in leaf, male female cone and trunk morphology.     

Detection of Penicillin-binding Proteins in the Endosymbiont of the Trypanosomatid Crithidia deanei

ABSTRACT. Growth by serial transfers of the trypanosomatid Crithidia deanei in culture medium containing 1 mg/ml of the β-lactam antibiotics ampicillin or cephalexin resulted in shape distortion of its endosymbiont. The endosymbiont first appeared as filamentous structures with restricted areas of membrane damage. An increase of electron lucid areas was also observed in the endosymbiont matrix. The continuous treatment with β-lactam antibiotics, resulted in endosymbiont membranes fragmentation; and later on the space previously occupied by the symbiont was identified as an electron lucid area in the host cytoplasm. The putative targets of β-lactam antibiotic were two membrane-bound penicillin-binding proteins (PBPs) detected in the Sarkosyl-soluble fraction of purified symbionts labeled with [³H]-benzylpenicillin. The apparent molecular weight of the proteins were 90 kDa (PBP1) and 45 kDa (PBP2). PBP2 represented 85% of the total PBP content in the membrane fraction of the endosymbionts. Competition experiments using the tested antibiotics and [³H]-benzylpenicillin showed that ampicillin and cephalexin have half saturating concentrations considerably higher than [³H]-benzylpenicillin and indicated that PBP1 is the probable lethal target of the antibiotics tested. These results suggest that a physiologically active PBP is present in the cell envelope of C. deanei endosymbionts and may play important roles in the control of processes such as cell division and shape determination.     

Climatic signals in growth and its relation to ENSO events of two Prosopis species following a latitudinal gradient in South America

Semiarid environments throughout the world have lost a major part of their woody vegetation and biodiversity due to the effects of wood cutting, cattle grazing and subsistence agriculture. The resulting state is typically used for cattle production, but the productivity of these systems is often very low, and erosion of the unprotected soil is a common problem. Such dry‐land degradation is of great international concern, not only because the resulting state is hardly productive but also because it paves the way to desertification. The natural distribution of the genus Prosopis includes arid and semiarid zones of the Americas, Africa and Asia, but the majority of the Prosopis species are, however, native to the Americas. In order to assess a likely gradient in the response of tree species to precipitation, temperature and their connection to El Niño southern oscillation (ENSO) events, two Prosopis species were chosen along a latitudinal gradient in Latin America, from northern Peru to central Chile: Prosopis pallida from a semi‐arid land in northern and southern Peru and P. chilensis from a semiarid land in central Chile. Growth rings of each species were crossdated at each sampling site using classical dendrochronological techniques. Chronologies were related with instrumental climatic records in each site, as well as with SOI and N34 series. Cross‐correlation, spectral and wavelet analysis techniques were used to assess the relation of growth with precipitation and temperature. Despite the long distance among sites, the two Prosopis species presented similar responses. Thus, the two species' growth is positively correlated to precipitation, while with temperature it is not. In northern Peru, precipitation and growth of P. pallida present a similar cyclic pattern, with a period of around 3 years. On the other hand, P. pallida in southern Peru, and P. chilensis also present this cyclic pattern, but also another one with lower frequency, coinciding with the pattern of precipitation. Both cycles are within the range of the ENSO band.     

Patterns of cryptic hybridization revealed using an integrative approach: a case study on genets (Carnivora, Viverridae, Genetta spp.) from the southern African subregion

Recent years have seen the development of molecular‐based methodologies to investigate hybridization and its impact on the evolutionary process. However, morphological characterization of hybrid zones has only scantily been considered, especially in zootaxa. Thus, the level of congruence between molecular and morphological characters when attempting to detect hybrids remains a poorly tackled area. The genets (genus Genetta) provide an ideal case study for further investigation of the respective contribution of morphology and DNA in hybrid zone characterization because (1) their morphology has recently been exhaustively explored and (2) the existence of hybrid zones in southern Africa was proposed in the literature. We assessed levels of hybridization among the southern African genets, and questioned the role of ecological factors on the hybridization patterns detected. We used an integrative approach involving nine discrete morphological characters and a diagnostic discriminant function, geometric morphometrics and sequences of cytochrome b including collection specimens. The combination of independent materials allowed us to accurately reassess the level of hybridization in southern African genets, and revealed cryptic, interspecific gene flows. Morphology unambiguously detected a low number of G. maculata × G. tigrina hybrids and rejected the hypothesis of a large intergradation zone in KwaZulu‐Natal, thus supporting the species status of the two genets. Cytochrome b analyses revealed: (1) cryptic, massive hybridization between G. tigrina and the sympatric G. felina, and (2) a trace of reticulation (one sequence) between G. tigrina and the allopatric G. genetta. The type specimen of G. mossambica Matschie, 1902 is considered to be a morphological hybrid between G. maculata and G. angolensis. Remarkably, the morphological approaches (discrete characters and morphometrics) proved complementary to conclusions derived from cytochrome b sequences. Whilst morphometrics was generally unable to accurately identify all putative hybrids, this approach revealed diagnostic cranial shape differences between recognized species as well as the cryptic G. ‘letabae’ (included in the super‐species G. maculata). Morphometrics also confirmed the diagnostic value and age dependency of discrete characters. Our integrative approach appeared necessary to the detection of cryptic hybridizations and to the comprehensive characterization of hybrid zones. The recurrent detection of hybrids exhibiting tigrina‐like coat patterns may suggest (1) asymmetric hybridization of G. tigrina males to females of other species and (2) positive selection for tigrina‐like phenotype in South African habitats, but these hypotheses will have to be further tested using other sources of evidence. Despite the precise mosaic of hybrid zones identified in southern African genets, the environmental factors that shape patterns of distribution of hybrids remain unclear. Nevertheless, in the light of our range reassessment, it appears that seasonality of precipitation and periods of annual frost may play stringent roles in the distribution of genets. The complementarity of our results based on morphology and molecules is regarded as encouraging for the further development of integrative approaches in order to better understand the complex phenomena that underlie hybridization processes. © 2005 The Linnean Society of London, Biological Journal of the Linnean Society, 2005, 86 , 11–33.