Microsatellite markers developed from Theobroma cacao L. expressed sequence tags

Theobroma cacao L. expressed sequence tags (ESTs) were converted into useful genetic markers for fingerprinting individuals and genetic linkage mapping. Primers were designed to microsatellite‐containing ESTs. Twenty‐two T. cacao accessions, parents of various mapping populations segregating for disease resistance and crop yield characteristics, were tested. Twenty‐seven informative loci were discovered with 26 primer pairs. The number of detected alleles ranged from two to 11 and averaged 4.4 per locus. All 27 markers could be mapped into at least one of the existing F₁ or F₂ populations segregating for agronomically important traits.     

Food resource matching by foraging tits Parus spp. during spring-summer in a Mediterranean mixed forest; evidence for an ideal free distribution

We analysed whether patterns of microhabitat use by Blue Tits Parus caeruleus , Great Tits Parus major and Crested Tits Parus cristatus inhabiting a mixed forest consistently matched the patterns of food availability experienced by foraging birds during spring-summer. The use of five microhabitats by each bird species (the foliage of three tree species, shrubs and ground) and the availability of food in trees during the prebreeding, breeding and post-breeding periods of the birds' annual cycle were measured. All three tit species foraged mainly in the outer part of tree canopies (small branches and leaves or needles). Tit distributions between tree species matched food resource distributions irrespective of overall food resource levels, which varied four-fold between the study periods, and tit species. Tits also exploited secondary microhabitats (shrubs and ground) in periods of low food availability; Blue Tits tended to use shrubs, whereas Great and Crested Tits foraged on the ground. Between-trees distributions fitted that expected from an ideal free distribution, suggesting that food availability and intraspecific exploitative competition were the main factors governing tree use by tits. In contrast, patterns of use of secondary microhabitats (shrubs and ground) seemed to indicate a role for the species-specific morphological configurations of each tit species since Blue Tits are better adapted to hang and tended to forage in shubs, whereas Great and Crested Tits are better adapted to feed on horizontal surfaces and tended to forage on the ground. No evidence of interspecific interactions was observed. Overall, the results pointed to an independent exploitation of Mediterranean mixed forest by each bird species, food availability and food accessibility being the main factors affecting microhabitat use by foraging tits.     

Origins and colonization history of pandemic Vibrio parahaemolyticus in South America

The dynamics of dissemination of the environmental human pathogen Vibrio parahaemolyticus are uncertain. The O3:K6 clone was restricted to Asia until its detection along the Peruvian coasts and in northern Chile in 1997 in phase with the arrival of El Niño waters. A subsequent emergence of O3:K6 strains was detected in austral Chile in 2004. The origin of these 1997 and 2004 population radiations has not yet been conclusively determined. Multiple loci VNTR analysis using seven polymorphic loci was carried out with a number of representative strains from Asia, Peru and Chile to determine their genetic characteristics and population structure. Asian and Chilean subpopulations were the most genetically distant groups with an intermediate subpopulation in Peru. Population structure inferred from a minimum‐spanning tree and Bayesian analysis divided the populations into two genetically distinct groups, consistent with the epidemic dynamics of the O3:K6 clone in South America. One group comprised strains from the original Asiatic population and strains arriving in Peru and Chile in 1997. The second group included the remaining Peruvian Strains and Chilean strains obtained from Puerto Montt in 2004. The analysis of the arrival of the O3:K6 clone at the Pacific coasts of South America has provided novel insights linking the origin of the invasion in 1997 to Asian populations and describing the successful establishment of the O3:K6 populations, first in Peru and subsequently in the South of Chile owing to a possible radiation of Peruvian populations.     

Does urbanization affect selective pressures and life‐history strategies in the common blackbird (Turdus merula L.)?

Urbanization, one of the most extreme land‐use alterations, is currently spreading, and the number of species confronting these changes is increasing. However, contradictory results of previous studies impede a clear interpretation of which selective pressure (nest predation or food limitation) is more important in urban habitats compared with natural situations, and whether birds can confront them by adjusting their life‐history strategies. We investigated life‐history syndromes of three common blackbird (Turdus merula) populations differing in their human influence (urban, rural, and woodland). We analysed daily nest predation and nestling starvation rates to assess the relative importance of these selection pressures in each habitat. Simultaneously, several life‐history traits were investigated to determine if T. merula seem adapted to their main source of selection. Food limitation was more important in the city, whereas nest predation was the most important selective force in the forest. The rural habitat was characterized by an intermediate influence of these two factors. Life‐history syndromes, as the covariation of a suite of traits, confirmed these results because T. merula seem well adapted to the main cause of selection in each habitat. Our results are consistent with urbanization imposing new challenges on birds, and that they adaptively respond to them. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 101 , 759–766.     

Ancient DNA reveals traces of Iberian Neolithic and Bronze Age lineages in modern Iberian horses

Multiple geographical regions have been proposed for the domestication of Equus caballus . It has been suggested, based on zooarchaeological and genetic analyses that wild horses from the Iberian Peninsula were involved in the process, and the overrepresentation of mitochondrial D1 cluster in modern Iberian horses supports this suggestion. To test this hypothesis, we analysed mitochondrial DNA from 22 ancient Iberian horse remains belonging to the Neolithic, the Bronze Age and the Middle Ages, against previously published sequences. Only the medieval Iberian sequence appeared in the D1 group. Neolithic and Bronze Age sequences grouped in other clusters, one of which (Lusitano group C) is exclusively represented by modern horses of Iberian origin. Moreover, Bronze Age Iberian sequences displayed the lowest nucleotide diversity values when compared with modern horses, ancient wild horses and other ancient domesticates using nonparametric bootstrapping analyses. We conclude that the excessive clustering of Bronze Age horses in the Lusitano group C, the observed nucleotide diversity and the local continuity from wild Neolithic Iberian to modern Iberian horses, could be explained by the use of local wild mares during an early Iberian domestication or restocking event, whereas the D1 group probably was introduced into Iberia in later historical times.     

Nest-site fidelity and breeding success in White Stork Ciconia ciconia

Nest-site fidelity is a life-history trait of birds that may produce benefits in terms of fitness. We studied the relationship between breeding success and nest fidelity in the White Stork Ciconia ciconia . We also studied how other factors such as age, sex, habitat, colony size and productivity in previous breeding attempts might interfere with this relationship. Our results showed that pairs with higher fidelity rates also have lower failure rates, and that breeding failure and productivity in the previous season influenced the frequency of nest change in the following season. In addition, a curvilinear relationship was found between age and nest fidelity. These results suggest that age is a major factor related to nest fidelity and therefore individual experience could explain this behaviour in the White Stork. Changing the nest involves a reproductive cost for which nest fidelity can be considered as an adaptive strategy to increase fitness.     

Bacterial degradability of an intrafeather unmelanized ornament: a role for feather‐degrading bacteria in sexual selection?

The impact of feather‐degrading bacilli on feathers depends on the presence or absence of melanin. In vitro studies have demonstrated that unmelanized (white) feathers are more degradable by bacteria than melanized (dark) ones. However, no previous study has looked at the possible effect of feather‐degrading bacilli on the occurrence of patterns of unmelanized patches on otherwise melanized feathers. The pied flycatcher Ficedula hypoleuca Pallas, 1764 is a sexually dimorphic passerine with white wing bands consisting of unmelanized patches on dark flight feathers. These patches are considered to be a sexually selected trait in Ficedula flycatchers, especially in males, where the patches are more conspicuous (larger and possibly whiter) than in females. Using in vitro tests of feather bacterial degradation, we compared the degradability of unmelanized and melanized areas of the same feather for 127 primaries collected from the same number of individuals in a population breeding in central Spain (58 males and 69 females). In addition, we also looked for sex differences in feather degradability. Based on honest signalling theory and on the fact that there is stronger sexual selection for males to signal feather quality than in females, we predicted that unmelanized areas should be more degradable by bacteria than melanized ones within the same feather, and that these unmelanized areas should also be more degradable in males than in females. We confirmed both predictions. Microstructural differences between cross‐section dimensions of unmelanized and melanized barbs, but not differences in the density of barbs within unmelanized and melanized areas of feathers in males and females, could partly explain differences in degradability. This is the first study to show differences in bacterial degradability among markings on the same feather and among unmelanized feather patches between males and females as predicted by sexual selection theory. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 105 , 409–419.