Consequences of climate and body size on the foraging performance of seed‐eating ants

1. Changes in climatic factors could have major effects on the foraging performance of animals. To date, however, no study has attempted to examine the concurrent effect of different climatic factors on foraging performance of individual organisms. 2. In the present study, this issue was addressed by studying changes in foraging performance of seed‐eating ant colonies of the genus Messor in response to variation in precipitation and ambient temperature along a macroecological gradient. In addition, we examined the way three colony‐level attributes, foraging distance, forager number, and variance in worker‐size, could affect foraging performance in those ants. Foraging performance was measured as size matching, i.e. the correlation between forager size and load size. The study was carried out for 2 years in six sites along a south‐north productivity gradient in a semi‐arid region of the Eastern‐Mediterranean. 3. Size matching increased with increased precipitation as well as with an increase in worker‐size variability, but slightly decreased with increasing temperatures, as predicted by foraging‐decision models. In contrast, foraging distance had no effect on size matching. Interestingly, size matching showed a unimodal relationship with forager number. 4. These results indicate that interplay between climate and body size affects foraging performance either directly via physiological constraints, or indirectly through their effect on food availability. Moreover, this is one of the first evidences to support the assumption that ant colonies can differ in their ability to optimally allocate their workforce in natural environments. This emphasises the importance of studying the way foraging strategies vary across environmental gradients at macroecological scales.     

Status of the South American tuberous legume Pachyrhizus tuberosus (Lam.) Spreng.: Field observations, taxonomic analysis, linguistic studies and agronomic data on the diversity of the South American Pachyrhizus tuberosus (Lam.) Spreng. complex with special reference to the identification of two new cultivar groups from Ecuador and Peru

The tuberous legume Pachyrhizus tuberosus is found in cultivation sporadically throughout the tropical lowlands of South America. As a result of field studies conducted in Bolivia, Ecuador, Peru and Venezuela, three distinct cultivar groups have been identified. Rare references presenting further evidence in support of this grouping, and yielding information on the cultivation history, are reviewed. The differences in morphology, agricultural practices, tuberous root quality and uses have been studied, as has the linguistic evidence of the origin and domestication processes. The herbarium and live material have been subjected to multivariate analyses in order to establish which easily observable phenotypic characters can be used in the identification of the three cultivar groups. This paper reports on the analysis of 23 morphological characteristics from 31 P. tuberosus cultivar records. The considerable potential of this cultivar/landrace complex and the possibilities of establishing in situ conservation initiatives are discussed. This revised version was published online in August 2006 with corrections to the Cover Date.     

Multiple sources of reproductive isolation in a bimodal butterfly hybrid zone

An important evolutionary question concerns whether one or many barriers are involved in the early stages of speciation. We examine pre‐ and post‐zygotic reproductive barriers between two species of butterflies (Heliconius erato chestertonii and H. e. venus) separated by a bimodal hybrid zone in the Cauca Valley, Colombia. We show that there is both strong pre‐ and post‐mating reproductive isolation, together leading to a 98% reduction in gene flow between the species. Pre‐mating isolation plays a primary role, contributing strongly to this isolation (87%), similar to previous examples in Heliconius. Post‐mating isolation was also strong, with absence of Haldane’s rule, but an asymmetric reduction in fertility (< 11%) in inter‐specific crosses depending on maternal genotype. In summary, this is one of the first examples of post‐zygotic reproductive isolation playing a significant role in early stages of parapatric speciation in Heliconius and demonstrates the importance of multiple barriers to gene flow in the speciation process.     

Revision of the species group Napaeus variatus (Gastropoda,Pulmonata, Buliminidae) from the Canary Islands,with description of five new species*

The Napaeus variatus (Webb & Berthelot, 1833) species group from the Canary Islands is reviewed from literature information, types, other museum specimens, and newly collected material. Anatomy data is newly provided for six species. Five new species are described: N. elegans and N. esbeltus from Tenerife, N. orientalis and N. beguirae from La Gomera, and N. exilis from Gran Canaria. Eight species lack a diverticulum and are referred to the subgenus Napaeus (Napaeus) Albers, 1850, whereas five species are provided with a diverticulum and arc referred to Napaeus (Napaeinus) Hesse, 1933. Four species cannot be assigned to a subgenus due to a lack of information. Keys of species from the different islands are provided.     

Some male Pied Flycatchers Ficedula hypoleuca in Iberia become collared with age

The development of a collar in Pied Flycatchers Ficedula hypoleuca in Spain is described and its ontogenetic and genetic variation and phenotypical correlates are analysed. Collared males were older than males having traces of collar or lacking one. Also, males showing a collar or trace of a collar had larger white forehead patches than those lacking a collar. Intrapopulation variation in both collar expression and white patch size, which might be genetically determined but phenotypically decoupled in temporal expression, resembles between-species variation among the black and white European flycatchers.     

Geographical and seasonal influences on the distribution of fungal endophytes in Quercus ilex

A systematic survey of the endophytic assemblages of Quercus ilex in central Spain has been performed, with the goal of evaluating the importance of geographical and seasonal factors on these fungal communities. Four sampling sites were selected; one of them was sampled twice, in the spring and the autumn. The collected plant material consisted of bark, twigs and leaves from eight trees per site. Fungal strains were isolated with the use of a surface-sterilization method with sodium hypochlorite. A total of 2921 fungal strains grouped into 149 'species' or morphological types were recovered. The 10 dominant species, with isolation frequencies >1.5%, were Pyrenochaeta sp., Periconiella anamorph of Biscogniauxia mediterranea (De Not.) Kuntze, Pseudonectria sp., Cryptosporiopsis quercina Petrak, Alternaria alternata (Fr:) Keissl., two undetermined coelomycetes, Penicillium funiculosum Thom, Diplodia mutila Fr. apud Mont. and Ascochyta sp. Medians of fungal species per tree were significantly different among the sampled sites. The isolation frequencies of the dominant species, as well as other less frequent species, were significantly dependent on the sampling site. The degree of endophytic infection and the diversity of fungal species were significantly higher in the spring. The frequencies of all dominant species at one of the sites depended significantly on the season, except for C. quercina , Acremonium sclerotigenum (F & V Moreau ex Valenta) Gams. and D. mutila . Cluster analysis of the whole endophytic mycoflora of the sampled trees suggested that the geographical factor affects the endophytic distribution patterns more significantly than the seasonal factor.     

Exceptionally preserved tadpoles from the Miocene of Libros,Spain: ecomorphological reconstruction and the impact of ontogeny upon taphonomy

McNamara, M.E., Orr, P.J., Kearns, S.L., Alcalá, L., Anadón, P. & Peñalver‐Mollá, E. 2010: Exceptionally preserved tadpoles from the Miocene of Libros, Spain: ecomorphological reconstruction and the impact of ontogeny upon taphonomy. Lethaia, Vol. 43, pp. 290–306. The Libros exceptional biota from the Upper Miocene of NE Spain includes abundant frog tadpoles (Rana pueyoi) preserved in finely laminated lacustrine mudstones. The tadpoles exhibit a depressed body, short tail, low tail fins, dorso‐laterally directed eyes and jaw sheaths; these features identify the Libros tadpoles as members of the benthic lentic ecomorphological guild. This, the first ecomorphological reconstruction of a fossil tadpole, supports phylogenetic evidence that this ecology is a conserved ranid feature. The soft‐tissue features of the Libros tadpoles are characterized by several modes of preservation. The space occupied previously by the brain is defined by calcium carbonate, the nerve cord is defined by calcium phosphate, and jaw sheaths and bone marrow are preserved as organic remains. Gut contents (and coprolites adjacent to specimens) comprise ingested fine‐grained sedimentary detritus and epiphyton. The body outline and the eyespots, nares, abdominal cavity, notochord, caudal myotomes and fins are defined by a carbonaceous bacterial biofilm. A similar biofilm in adult specimens of R. pueyoi from Libros defines only the body outline, not any internal anatomical features. In the adult frogs, but not in the tadpoles, calcium phosphate and calcium sulphate precipitated in association with integumentary tissues. These differences in the mode of preservation between the adult frogs and tadpoles reflect ontogenetic factors. □Anuran, ecology, soft‐tissue, tadpoles, taphonomy.