Papers by carlos de la cruz
Behavioural Processes, 2016
Individuals within animal groups may differ in personality and degree of familiarity raising the ... more Individuals within animal groups may differ in personality and degree of familiarity raising the question of how this influences their social interactions. In Iberian magpies Cyanopica cooki, a portion of first-year males engage in cooperative behaviours and dispersal, allowing addressing this question. In this study, we first investigate the relationship between colony familiarity (native versus foreign) and reproductive status (breeding versus helping) of males during 21 years. Secondly, we measure the exploratory behaviour and monitor reproductive status of a sample of individuals with different colony familiarity during 2 years. Long-term monitoring revealed that foreign individuals were more likely breeders. The analysis on the subset of individuals in which exploratory behaviour was measured revealed a mediatory effect of exploratory behaviour in the association between colony familiarity and helping behaviour. Specifically, among foreign individuals, higher explorative males were more frequently involved in helping behaviour than lower explorative ones. Conversely, among native males, breeders were more explorative than helpers. Our results suggest that aspects of personality may mediate the value of familiarity in reproductive tasks in social species.
Estudios Sobre Comportamiento Animal Xxv Anos De La Sociedad Espanola De Etologia 2010 Isbn 978 84 7723 920 8 Pags 223 230, 2010
Revista De Matematica Teoria Y Aplicaciones, Jul 8, 2011
En Ramírez (2001) se introdujo el problema de coloración robusta generalizado (PCRG), el cual res... more En Ramírez (2001) se introdujo el problema de coloración robusta generalizado (PCRG), el cual resuelve problemas de horarios que consideran restricciones del tipo: dos eventos no pueden realizarse a la misma hora y debe haber al menos d días entre dos eventos. El PCRG es una coloración robusta, en que dada una gráfica y un número fijo de colores, no necesariamente el número cromático, considera la distancia entre colores como penalización de las aristas complementarias. Se demostró que el problema es NP-Completo, por lo que es necesario utilizar métodos aproximados para encontrar buenas soluciones en un tiempo razonable. En este trabajo se presenta un híbrido de un algoritmo genético con uno de búsqueda local para casos de 30 a 120 horas por semana, se demuestra que para algunos la solución eś optima y en otros se encuentran soluciones muy prometedoras. Palabras clave: horarios; restricciones especiales; heuristícas.
Revista De Matematica Teoria Y Aplicaciones, Dec 1, 2011
Evolution; international journal of organic evolution, Jan 13, 2016
Fitness can be profoundly influenced by the age at first reproduction (AFR), but to date the AFR-... more Fitness can be profoundly influenced by the age at first reproduction (AFR), but to date the AFR-fitness relationship only has been investigated intraspecifically. Here we investigated the relationship between AFR and average lifetime reproductive success (LRS) across 34 bird species. We assessed differences in the deviation of the Optimal AFR (i.e., the species-specific AFR associated with the highest LRS) from the age at sexual maturity, considering potential effects of life-history as well as social and ecological factors. Most individuals adopted the species-specific Optimal AFR and both the mean and Optimal AFR of species correlated positively with lifespan. Interspecific deviations of the Optimal AFR were associated with indices reflecting a change in LRS or survival as a function of AFR: a delayed AFR was beneficial in species where early AFR was associated with a decrease in subsequent survival or reproductive output. Overall, our results suggest that a delayed onset of repr...
RESUMEN.-Variación del hematocrito durante el periodo reproductor en el Rabilargo Cyanopica cyanu... more RESUMEN.-Variación del hematocrito durante el periodo reproductor en el Rabilargo Cyanopica cyanus. Algunos estudios previos han sugerido que el hematocrito podría estar relacionado con diversos factores del ciclo biológico de las aves. En este trabajo se analizan las variaciones del hematocrito encontradas en el Rabilargo Cyanopica cyanus durante el periodo reproductor, relacionándolas con factores como la edad, sexo, estatus reproductor, muda, mes y año de estudio. No hubo significación en las diferencias interanuales. Se apreciaron diferencias significativas al enfrentar las diferentes clases de edad, de manera que los pollos presentaron valores más bajos que los juveniles y adultos, sin encontrarse diferencias entre estas dos últimas clases. En ambos sexos se observó una tendencia a la disminución del hematocrito a lo largo del periodo reproductor, pero las diferencias únicamente fueron significativas en el caso de los machos entre marzo y junio. No se detectaron diferencias significativas entre machos ayudantes y reproductores. Los altos niveles de andrógenos (que estimulan la eritropoyesis) en los machos al comienzo de la estación reproductora y su posterior descenso podrían explicar, al menos en parte, el patrón estacional de variación del hematocrito. Tampoco se han encontrado diferencias en junio, cuando se solapan el final de la estación de cría y el comienzo de la muda, entre individuos que estaban mudando y aquellos que aún no la habían iniciado.
Ringing & Migration, 1992
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Ringing & Migration, 2007
Like all corvids, the Azure-winged Magpie Cyanopica cyanus is sexually monomorphic in plumage, ma... more Like all corvids, the Azure-winged Magpie Cyanopica cyanus is sexually monomorphic in plumage, making it difficult to distinguish between males and females in the field. We examined sexual size dimorphism in a population of Iberian Azure-winged Magpies C.c. cooki and used a discriminant function analysis based on five morphological characters to determine the sex of first-year and adult individuals. Females were significantly smaller than males for all tested variables within each age class except for keel length of first-year individuals. In both sexes, wing length of adults was greater than that of yearlings, but only males showed significant differences in tail length between age classes (longer in first-year birds). Stepwise discriminant analysis indicated that tail length and head plus bill length were the most accurate variables in a discriminant function model, predicting the sex of yearlings with about 90% accuracy. Adding wing length to the model yielded the same level of accuracy for adults. We propose a simple system to sex Iberian Azure-winged Magpies, using only two or three variables easily measured in the field, which provides classification with a high level of accuracy. Figure 3. Size segregation of a) first-year, and b) adult, male (filled symbols) and female (open symbols) Azure-winged Magpies, with contours corresponding to given probabilities of being male.
Journal of wildlife diseases, Jan 19, 2016
We identified and compared gross and microscopic lesions associated with the cestode, Parorchites... more We identified and compared gross and microscopic lesions associated with the cestode, Parorchites zederi, in the digestive tracts of three species of penguins (Spheniscidae): the Chinstrap ( Pygoscelis antarctica ), Gentoo ( Pygoscelis papua ), and Adélie Penguins ( Pygoscelis adeliae ). The gastrointestinal tracts of 79 recently dead individuals (71 chicks and eight adults) were collected in locations throughout the Antarctic Peninsula during summer field trips in 2006-2009. Parorchites zederi was found in the small intestine of 37 animals (47%), and 23 (62%) of these had parasite-associated lesions. The cestodes were either free in the intestinal lumen, clustered within mucosal ulcers, or deeply embedded in the intestinal wall. Histopathologic changes were most severe in adult Gentoo Penguins and included transmural fibrogranulomatous enteritis, hemorrhage, and edema. This report of pathology associated with P. zederi in the digestive tracts of penguins can serve as reference to m...
Journal of Avian Biology, 2008
Journal of Helminthology, 2016
Stegophorus macronectes (Johnston & Mawso... more Stegophorus macronectes (Johnston & Mawson, 1942) is a gastrointestinal parasite found in Antarctic seabirds. The original description of the species, which was based only on females, is poor and fragmented with some unclear diagnostic characters. This study provides new morphometric and molecular data on this previously poorly described parasite. Nuclear rDNA sequences (18S, 5.8S, 28S and internal transcribed spacer (ITS) regions) were isolated from S. macronectes specimens collected from the chinstrap penguin Pygoscelis antarctica Forster on Deception Island, Antarctica. Using 18S rDNA sequences, phylogenetic analyses (maximum likelihood, maximum parsimony and Bayesian inference) of the order Spirurida were performed to determine the phylogenetic location of this species. Primer pairs of the ITS regions were designed for genus-level identification of specimens, regardless of their cycle, as an alternative to coprological methods. The utility of this molecular method for identification of morphologically altered specimens is also discussed.
Ethology, 2003
Helping to rear the offspring of others may be a way for younger birds to gain access to future r... more Helping to rear the offspring of others may be a way for younger birds to gain access to future reproduction especially when turnover of breeding opportunities is low. However, this explanation is not applicable to cases where adults also help, or when roles shift between helpers ...
Toxicology Letters, 2008
tar albino rats and mice were used to assess sub-acute and acute toxicity respectively. For the a... more tar albino rats and mice were used to assess sub-acute and acute toxicity respectively. For the acute toxicity on mice we used increasing (0.6; 1.3; 2.5; 5; 10 g/kg) oral doses of dry extract dissolved in 1 ml of water for B. pilosa and R. vomitoria while the two F. macrophylla extracts were dissolved in 1 ml of corn oil. This experiment lasted 14 days during which mice had 1 ml of the daily dose. Control group received water only. The animals had regular supply of food and water. The method described by Miller and Tainter (1944) was used to determine the DL50. For the sub acute toxicity, rats were given daily for 28 days oral doses of 0.3, 0.6 and 1.3 g/kg extract of R. vomitoria and F. macrophylla extracts; extract of B. pilosa were given at the daily dose of 1.3, 2.5 and 5 g/kg. The animals had regular supply of food and water too. At the end of the experiment the animals were sacrificed after an overnight fast. Blood was collected for hematological and biochemical analysis. Liver and kidney were removed from each rat for histopatholgical examinations (Gabe, 1968). Results: Acute toxicity showed that B. pilosa was less toxic. R. vomitoria and F. macrophylla (stem bark and root bark) had a DL50 of 2.87 and 3.1 respectively. F. macrophylla roots decreased significantly red blood cells and white blood cells counts. R. vomitoria seemed to increase blood cholesterol. B. pilosa and F. macrophylla roots at the higher doses was hyperglycemic. The activities of all the enzymes used as markers of liver cytolysis increased showing a side effect of these plants on the liver. The concentrations of kidney markers like creatinin and urea did not change. Histopathological examinations of the liver and the kidney confirmed the hepatotoxicity of the extracts and reveal some histological change on the kidney. Conclusion: This study showed that these medicinal plants can be dangerous if used intensively and for a long time by traditional healers.
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Papers by carlos de la cruz