Catálogo de publicaciones - libros

We have traced a fewlines in Hobbes’s development that led through the years in Paris. It seems fair to say that, although he accommodated himself to the new intellectual and social parameters within which he lived, he did not greatly change the address of his studies, at least as regards religion and politics, and his eye remained fixed on the English political situation. But, while he grew both as a theorist and in his willingness to express what he recognized were controversial views, he likely long suppressed his true views regarding the materiality of God for fear of social opprobrium and religious persecution. He did not change his views, however, as is evident in his avowal and defense of them late in life.

The link we have presumed between his theology and his physics is largely undeveloped in the English , so there is an unstated content at work behind the text. This may be one reason why some have sought to read double meanings into it, though we may doubt whether its avowal was necessary for his purposes in that work or would have helped its reception. When he states his views, the link is described from within strictly delimited noetic parameters.

In the 1651 text, the ‘God of causes’ does however play a prominent role in his theory of the public person as public theologian by way of the religion of ‘rational worship.’ These elements mark the culmination of several themes that were present in , developed in and then elaborated in with an innovative and striking theory about Aristotle’s theory of language and its influence in Christian theology.

For the paleontologically oriented purposes of this review, migration can be conveniently considered from several aspects, some of which cannot be definitely identified nor definitely interpreted in the fossil record. In favourable circumstances, inference drawn from Schäfer’s concept of “actuopaleontology” can provide enlightenment. Several categories are briefly discussed here, to wit, seasonal migration, unidirectional migration driven by directed climatic, and or, geological factors, such as changes in the configuration of ocean basins, competition between species and the battle for survival and overpopulation, and enforced migration due to deep-sea oceanic currents. Additionally, and of particular paleontological consequence there is the contrasting circumstance of nekroplanktonic dispersal.

Sixty-four ostracod species and morphs in 130 samples from five sections along the Nile Valley between Minia and Maghagha cities could define the paleoenvironmental conditions that prevailed during the Eocene in the study area. Cluster analysis based on the Jaccard coefficient of similarity (the paired group average method) led to the distinction of three biofacies of ostracod assemblages, each of them with its particular paleoenvironment. The Minia biofacies represents the early Eocene, and is characterized by deposition in an inner to outer shelf environment. The Maghagha biofacies is middle Eocene and represents a restricted shallow water environment, possibly with more or less reduced salinity. At the base of the sequence, these restricted conditions were accompanied by reduced, dissolved oxygen conditions. At the top, calm water conditions prevailed. The Qarara biofacies is also middle Eocene in age and was deposited in turbulent water conditions, gradually shallowing over time. On the other hand, the Samalut Formation, which was barren of microfossils, can be attributed, according to its lithological composition, to a particular type of facies representing a shallow marine environment. The ostracod species of the study area provide evidence of distinct migration of ostracods during the Paleogene along the southern shores of the Tethys.

Microscopic observations as well as geometric morphometric analyses of specimens belonging to three previously identified species of the genus Siddiqui ( and ), from the middle Eocene of Egypt, led to conclude that these three species should be considered as three morphs of one species ( (Bassiouni)). The results reveal that the use of quantitative shape analyses is the most powerful tool for differentiating forms within the species exhibiting shape polymorphism in their life cycles. Nonetheless, the microscopic observations of the different characteristics of the organisms should be a helpful tool in identifying the ornamental polymorphism. The study of the environmental and geographical distribution of MTA and its two related morphs (MTB, MTC) could interpret the lack of economic phosphate deposits in the Paleogene of Egypt, the Middle East and North Africa. This study exemplifies adaptability as a parallel way to migration for organisms to survive.

Insects migrate in many different scales ranging from a few metres to many hundreds of kilometres. The hosts a suite of widely accepted definition of insect migration. The predisposition of some insects for migration is called and involves the condition of the flight muscles, the oviposition period and timing, the fecundity, the energy uptake and wing polymorphism. Pheromones are another useful trait of migratory insects since they are used to gather the scattered migrants in a restricted space. The cost of a migration event was compared to the cost of other solutions to the problems of overcrowding or habitat destruction. In many cases migration is the less costly solution apart from other benefits that may incur to the insect such as natural selection, since migration is a safe estimator of the abilities of the insect and its health status. To estimate the cost of insect migration several authors have proposed formulas with hardly estimable parameters. Moreover, it is very difficult for the insect to manipulate parameters such as the migration time and the available energy for migration. It is speculated that in evolutionary time, the manipulation in evolutionary time of some parameters is not possible in the physiological context of an insect, and for this, a migration event may last more than two or three generations. The migration of insects is now studied using, apart from biological methods, new approaches such as specifically constructed entomological radars. Climate change in general and global warming in particular affect insect migration in several ways. It causes phenological shifts to the host plants, destruction of habitat, extensive fragmentation of landscapes, marine incursions and faunal reshuffling. Also, many insects and host plants are responding in different ways to global warming and greenhouse gases. In Mediterranean insects such as there is a short scale migration primarily caused by searching for ideal climatic conditions.

Cold-water molluscan fauna originated in the North Pacific in accordance with the worldwide cooling events around the latest Eocene. The westward trans-Pacific migration of the cold-water molluscs occurred during the early to early middle Miocene, owing to shifting climatic belts and “ecological opportunity” rather than current direction. In contrast, the eastward migration of the cold-water molluscs occurred in cool climate ages from the early Oligocene to Holocene. As a result of the Plio-Pleistocene cooling, cold-water species spreaded to the Yellow and the East China Sea through the Japan Sea. Shifting climatic belts thus affected the zoogeographic range of cold-water species.

Differences in integumentary permeability dictate alternative life history strategies in amphibians and reptiles. Limiting resources for amphibians are chiefly associated with availability of water and, as a consequence, amphibian migrations are chiefly associated with movements to and from aquatic breeding habitats. These cyclic migrations from breeding to overwintering sites may be direct, or may be interrupted by periods of residence at foraging sites. In general, migrations take place over relatively short distances and are constrained by the problem of water balance associated with exposure during longer overland journeys. Many amphibians exhibit complex mechanisms of orientation involving multiple sensory modalities and are capable of precise homing abilities.

Among reptiles, migrations are chiefly associated with travel to and from egg laying sites, as displayed by turtles, or communal hibernacula, as is characteristic of some snakes. Marine turtles, in particular, undertake long distance migrations (up to thousands of kilometers) to reach nesting beaches and, sometimes, foraging grounds. In these chelonians, complex patterns of movement vary ontogenetically, as well as by gender and species. A variety of cues are used to locate destinations, including celestial, geomagnetic, olfactory, auditory, thermal, wave, and current pattern signals; however, evidence of a map-compass system of navigation is equivocal.

The migratory patterns of amphibians and reptiles often bring them into conflict with human resource utilization. For amphibians, breeding migrations that cross busy roads or areas turned over to agricultural production lead to mass mortality. Marine turtle migratory pathways often result in conflicts with fishery activities. Knowledge of life history strategies and associated migratory behavior is essential for effective conservation measures.

The long-toed salamander () is a widespread inhabitant of the Cordilleran Region of western North America. The Cordilleran ice sheet retreated when climates changed at the end of the Pleistocene. This setting provides a natural experiment for phylogeographic tests of post-glacial migration. As migration occurs, the demographics of populations change; these changes are imprinted into the gene frequencies of descendant populations. Species ranges shifted as migrants inhabited tolerable post-glacial environments, and new genealogical mixtures formed as populations came into secondary contact. Historical climate, ecology, and geography impacted the range dynamics and consequent population genetics of the long-toed salamander. This systematic study of mitochondrial DNA tests biogeographic patterns using phylogenetic trees, nested phylogeographic clade analysis, and mismatch distributions. Phylogenetic congruence is tested first in a partitioned versus an intersected arrangement of two mitochondrial loci, including 95 cytochrome b and 103 intergenic spacer sequences. Nested phylogeographic clade analysis provides an explicit system to correlate lineages and their mismatch distributions. Although mismatch distributions operate ideally in high-migration species, and the long-toed salamander migrates little among contemporary populations, there is reason to suspect that waif dispersal increased with changes in fluvial dynamics following glacial retreat. Clade patterns support a deep vicariance across the central interior and reveal seven Pleistocene refugia. Waves in mismatch distributions indicate that population sizes increased in lineages residing in refugia near the ice margins at this time. The phylogenetic identities that spread away from refugia and their genetic patterns are placed into a historical pre- and post-glaciated context.

The configuration of emerged land masses as well as the distribution of suitable habitats are two important constraints for migration of land mammals. The evolution of late Miocene European land mammal faunas seems to be related to climatic change, which consisted in a general cooling and an increase in seasonality starting by the late Miocene. The pre-existing subtropical evergreen forests were replaced by mixed mesophytic ones at higher latitudes, while in the peri-Mediterranean regions the forest cover was fragmented. The Vallesian Crisis, which implied the disappearance of forest-adapted taxa and a general diversity decay in Western Europe by the beginning of the late Miocene, has been related to main climatic changes. This crisis is a well-established event in the Iberian Peninsula, however the response of mammal communities in other areas is still debated. The goals of present work are to refine chronologic and geographic limits of the Vallesian Crisis. Data input consists in a series of fossil mammal sites covering most of the middle and all the late Miocene (13.8 – 4.9 Ma). Provinciality has been studied using cluster analysis, and results indicate the maintenance of three main bioprovinces (Greek-Iranian, Iberian and Central European) during most of the time span. Diversity and origination and extinction rates have been calculated for all Europe and for each main bioprovince whenever possible. The results show that diversity increased during the late Vallesian and the Turolian in the Greek-Iranian bioprovince because of the development of open-country herbivore faunas while diversity remained stable in Central Europe. A decay in diversity started in the Iberian Peninsula by the early Vallesian and genera richness kept descending during the Turolian. Although the environment was rather similar in East and West, Turolian mammal faunas from the Iberian Peninsula are very poor and show few eastern immigrants. We suggest that mixed mesophytic forests covering most of Central Europe acted as an ecological filter, preventing the migration of open-country adapted taxa from Anatolia.

The role of dispersal events in shaping patterns of geographic differentiation of biotas has been often studied regarding to invasive events occurring in short periods of time. However, migrations of species from one area to another are occurring continuously. Thus, patterns on differentiation diversity may be affected by the connectivity among areas. We provide evidence of this fact using the recent mammal faunas at the Iberian Peninsula. When compared with differences in environment and habitat structure, connectivity-mediated distances where the most important factor affecting -diversity patterns at 100x100 km scale. Moreover, most of the explanatory capacity of environmental differences could not be separated from that attributable to connectivity. We developed a model that links patterns in -diversity with geomorphologically-based connectivity using these recent data, and tested it on the patterns of macromammal variation among sedimentary basins during the Iberian Neogene. -diversity values where much higher than those observed for recent faunas, and our model was unable to predict Neogene patterns. A critical discussion on the causes of this lack of agreement among recent patterns and those observed from fossil data is provided.