Darwin y las islas

Darwin y las islas. En su viaje de circunnavegación a bordo del Beagle, Charles Darwin visita numerosas islas. Las extraordinarias observaciones llevadas a cabo en las mismas sientan las bases de su pensamiento evolutivo e influyen decisivamente en la formulación posterior de sus teorías. Las islas son también objeto de brillantes observaciones geológicas que desembocan en la propuesta de una hipótesis general, vigente hoy día, sobre la formación de los atolones coralinos. Asimismo, Darwin elabora hipótesis biogeográficas sobre el proceso de colonización insular a partir de las evidencias acumuladas en su largo viaje. A pesar de su brevedad, probablemente la visita a las islas Galápagos es la etapa más importante del viaje de Darwin. Los especímenes y datos obtenidos de tortugas terrestres y pinzones sirven años más tarde de sólida base para la explicación de la radiación adaptativa de un grupo de especies a partir de un antecesor común. Menos conocida es quizás la esencial influencia de las observaciones sobre los sinsontes de Galápagos (familia Mimidae), a partir de las cuales Darwin esboza, ya durante el viaje de regreso, las primeras reflexiones evolucionistas en sus famosas notas ornitológicas. Las islas han jugado pues un papel esencial en la génesis de la teoría de la evolución por selección natural y, de hecho, constituyen hoy el mejor laboratorio natural para el estudio de los procesos selectivos. El caso paradigmático es el de la extraordinaria investigación llevada a cabo durante varias décadas en Galápagos por Peter y Rosemary Grant sobre los pinzones de Darwin.Darwin and the islands. In his journey of circumnavigation aboard H.M.S. Beagle, Charles Darwin visited several islands. His extraordinary observations lay the foundations of evolutionary thought and influenced the subsequent development of his theories. The islands are also perceptively studied from a geological viewpoint, leading to the proposal of a general hypothesis, still extant, on the formation of coralline atolls. Likewise, Darwin developed some biogeographical hypotheses on the process of colonization of the islands from the evidence accumulated during his long journey. Perhaps the visit to the Galapagos Islands is, despite its brevity, the most important step of the trip. Specimens and data collected from tortoises and finches served years later as a solid basis for the explanation of adaptive radiation of a group of species from a common ancestor. Probably less well known is the crucial influence of observations on Galapagos’ mockingbirds (family Mimidae), from which Darwin outlined, within his famous ornithological notes and during the return journey, the first thoughts of his evolutionary theory. Since Darwin’s times, islands have played a key role in the genesis of the theory of evolution by natural selection. In fact, islands are today the best natural laboratory for the study of selective processes. The paradigmatic case is the remarkable research conducted in the Galapagos over several decades on Darwin’s finches by Peter and Rosemary Grant.Darwin i les illes. En el seu viatge de circumnavegació a bord del Beagle, Charles Darwin visita nombroses illes. Les extraordinàries observacions que hi duu a terme estableixen les bases del seu pensament evolutiu i influeixen decisivament en la formulació posterior de les seves teories. Les illes són també objecte de brillants observacions geològiques que desemboquen en la proposta d’una hipòtesi general, vigent encara avui, sobre la formació dels atol·lons coral·lins. Així mateix, Darwin elabora hipòtesis biogeogràfiques sobre el procés de colonització de les illes a partir de les evidències acumulades en el seu llarg viatge. A pesar de la seva brevetat, probablement la visita a les Illes Galápagos és l’etapa més important del viatge de Darwin. Els espècimens i dades obtingudes de tortugues terrestres i pinsans, serveixen anys més tard de sòlida base per a l’explicació de la radiació adaptativa d’un grup d’espècies a partir d’un antecessor comú. Menys coneguda és potser l’essencial influència de les observacions sobre els sinsonts de Galápagos (família Mimidae), a partir de les quals Darwin esbossa, ja durant el viatge de retorn, les primeres reflexions evolucionistes en les seves famoses notes ornitològiques. Les illes han jugat doncs un paper essencial en la gènesi de la teoria de l’evolució per selecció natural i, de fet, constitueixen avui el millor laboratori natural per a l’estudi dels processos selectius. El cas paradigmàtic és el de l’extraordinària investigació portada a terme durant diverses dècades a Galápagos per Peter i Rosemary Grant sobre els pinsans de Darwin

Assessing factors involved in determining fluctuating asymmetry in four insular populations of the Balearic lizard Podarcis lilfordi

Abstract. In animals, developmental stability is frequently assessed by the level of fluctuating asymmetry. Several environmental and genetic stress factors can increase the developmental instability in a population. Anyhow, the use of fluctuating asymmetry as a measurement of developmental instability and its relationship to other measurements of genetic and environmental stress, remain controversial. We studied this subject in the Balearic lizard, Podarcis lilfordi, and examined four populations inhabiting different coastal islets of Minorca (Balearic Islands, Spain). These populations show clear ecological and genetic differences that allowed us to study factors potentially determining the level of fluctuating asymmetry. We examined the following predictions: (1) fluctuating asymmetry will increase on smaller islands; (2) fluctuating asymmetry will increase on islands with a higher lizard density; (3) fluctuating asymmetry will increase on islands with more heavily parasitized lizards; and (4) populations with higher inbreeding levels would be more susceptible to environmental stress. Our results would partially support the fourth prediction of a higher fluctuating asymmetry in populations with lower genetic variability and, consequently, a higher inbreeding level. Probably, other environmental factors modulate this relationship

Rediscovery of a population of the Balearic lizard Podarcis lilfordi (Squamata, Lacertidae) on Menorca (Balearic Islands)

Abstract not availabl

Escape by the Balearic Lizard (Podarcis lilfordi) is affected by elevation of an approaching predator, but not by some other potential predation risk factors

Many predation risk factors to affect escape behavior by lizards, but effects of some potential risk factors are unknown or are variable among species. We studied effects of several risk factors on escape responses by the Balearic lizard (Podarcis lilfordi, Lacertidae) on escape responses. Escape was elicited by an approaching experimenter who recorded flight initiation distance (predator-prey distance when escape begins) and distance fled. When an experimenter approached from above (upslope), flight initiation distance and distance fled were longer than when the experimenter approached from below. This novel effect suggests that lizards exposed to aerial predation might have been naturally selected to respond rapidly to predators approaching from above or that effects of path inclination of escape ability may differ between predators and prey in a manner requiring a larger margin of safety during approaches from above than below. Although sex differences in aspects of escape occur in some lizards, including lacertids, no sex difference was observed in P. lilfordi. Because vigilance and some other aspects of antipredatory behavior exhibit cortical lateralization, we tested effects of approach from the left and right sides of lizards. As predicted by optimal escape theory, side of approach did not affect flight initiation distance. Because many lizards have color vision and respond to pigmentation of conspecifics in social settings, researchers have often worn only drably colored clothing when simulating predators. This precaution may be unnecessary because flight initiation distance did not differ among investigator shirt colors (red, orange, olive)

Thermal ecology of Podarcis siculus (Rafinesque-Schmalz, 1810) in Menorca (Balearic Islands, Spain)

We studied the thermal ecology of an introduced population of the Italian wall lizard, Podarcis siculus, in Menorca (Balearic Islands, Spain). We measured field body temperatures of adult lizards, as well as air and substrate temperatures at their capture places, during spring and summer. We assessed the relations between body and air temperatures, and between body and substrate temperatures, for both seasons. We studied the preferred temperature range of P. siculus in a laboratory thermal gradient. In addition, we recorded the operative temperatures of the habitat of the Italian wall lizard during summer. Then, we calculated the three indexes of behavioural thermoregulation for summer: thermal quality of the habitat, accuracy of thermoregulation, and effectiveness of thermoregulation. As expected, our results show that Italian wall lizards achieved significantly higher body temperatures during summer than during spring. Body temperatures were not significantly related to air temperatures in spring, but the correlation was significant in summer. In addition, body temperatures were not significantly related to substrate temperatures for any season. The preferred temperature range of the species was similar for males and females: 28.40-31.57 °C. Introduced Italian wall lizards of Menorca are effective thermoregulators, with an effectiveness of 0.82 during summer

On the feeding ecology of Pelophylax saharicus (Boulenger 1913) from Morocco

The Sahara frog is the most common amphibian found in North Africa. However, the knowledge of its natural history is rather fragmentary. In the present work we studied the trophic ecology of Pelophylax saharicus at some areas of Morocco through the analysis of 130 gastric contents. We did not find any significant sexual dimorphism in body size of adult individuals. Consumed prey show similar sizes in both sexes, while bigger frogs normally eat larger prey. As in other Palearctic frogs, the diet is basically insectivorous, including terrestrial and aquatic prey. We found some differences in the diet of juveniles, with a higher proportion of flying prey, probably indicating a foraging strategy closer to ambush hunting. In the Atlas region, the high consumption of slow-moving terrestrial prey, as Gastropoda, stands out. Only in the Atlas region, the diet was similar to that described from other areas of North Africa, as Tunisia

Caracterización lesional y etiológica de neumonías en vacuno de cebo sacrificado en matadero

Trabajo presentado a la: XXVII Reunión de la Sociedad Española de Anatomía Patológica Veterinaria. (Barcelona, España, 17-19 junio de 2015).Peer Reviewe

Caracterización lesional y etiológica de neumonías en vacuno de cebo sacrificado en matadero

El Complejo Respiratorio Bovino constituye una importante enfermedad en bovinos de cebo. Los agentes etiológicos principalmente implicados en este síndrome incluyen virus (BoHv1,PI-3, BVDv, bRSV), bacterias (Mannheimia haemolytica, Pasteurella multocida, Histophilussomni, Trueperella pyogenes) y Mycoplasma bovis. Dentro de este síndrome, la neumonía es la lesión más relevante. Este estudio se ha realizado en animales de cebo sacrificados en matader

Estructura en una taxocenosis de Lacertidae (Sauria, Reptilia) del Sistema Central

Se estudia una taxocenosis de lacertidae compuesta por 8 especies: Lacerta lepida, Lacerta schreiberi, Lacerta monticola, Acanthodactylus erythrurus, Psammodromus algirus, Psammodromus hispanicus, Podareis hispánica y Podareis bocagei. La mayor parte de ellas se comportan como generalistas alimenticios, si bien A. erythrurus parece especializarse en la mirmecofagia mientras que L. monticola aparece como un estenófago «forzoso». Los valores de solapamiento en cada una de las dimensiones del nicho indican que la dimensión espacial y la preferencia de habitat actúan en primer término. Sin embargo la segregación se produce conjuntamente gracias a la interacción de las tres dimensiones consideradas que actúan independientemente.A study on taxocenosis of Lacertidae with 8 species: Lacerta lepida, Lacerta schreiberi, Lacerta monticola, Acanthodactylus erythrurus, Psammodromus algirus, Psammodromus hispanicus, Podareis hispanica and Podareis bocagei in the western part of the Sistema Central (Iberian Peninsula) has been carried out. Most of these behave as feeding generalists but A. erythrurus seems to specialize in mymecophagy whereas L. monticola turns out to be a «forced» sthenophage. The overlap values in each niche dimension suggest that the spatial dimension and habitat preference are the most important factors. However, segregation is produced jointly due to the interaction of the three dimensions considered which act interdependently