Diversity and evolution of sexually dimorphic mental and lateral glands in Cophomantini treefrogs (Anura: Hylidae: Hylinae)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Thoughts on the diversity of convergent evolution of bioluminescence on earth

The widespread independent evolution of analogous bioluminescent systems is one of the most impressive and diverse examples of convergent evolution on earth. There are roughly 30 extant bioluminescent systems that have evolved independently on Earth, with each system likely having unique enzymes responsible for catalysing the bioluminescent reaction. Bioluminescence is a chemical reaction involving a luciferin molecule and a luciferase or photoprotein that results in the emission of light. Some independent systems utilize the same luciferin, such as the use of tetrapyrrolic compounds by krill and dinoflagellates, and the wide use of coelenterazine by marine organisms, while the enzymes involved are unique. One common thread among all the different bioluminescent systems is the requirement of molecular oxygen. Bioluminescence is found in most forms of life, especially marine organisms. Bioluminescence in known to benefit the organism by: attraction, repulsion, communication, camouflage, and illumination. The marine ecosystem is significantly affected by bioluminescence, the only light found in the pelagic zone and below is from bioluminescent organisms. Transgenic bioluminescent organisms have revolutionized molecular research, medicine and the biotechnology industry. The use of bioluminescence in studying molecular pathways and disease allows for non-invasive and real-time analysis. Bioluminescence-based assays have been developed for several analytes by coupling luminescence to many enzyme-catalysed reactions. Received 17 February 2012, accepted 27 March 2012, first published online 2 May 2012

Evolution of signal form

Visual signals, used for communication both within and between species, vary immensely in the forms that they take. How is it that all this splendour has evolved in nature? Since it is the receiver’s preferences that cause selective pressures on signals, elucidating the mechanism behind the response of the signal receiver is vital to gain a closer understanding of the evolutionary process. In my thesis I have therefore investigated how receivers, represented by chickens, Gallus gallus domesticus, respond to different stimuli displayed on a peck-sensitive computer screen. According to the receiver bias hypothesis, animals and humans often express biases when responding to certain stimuli. These biases develop as by-products of how the recognition mechanism categorises and discriminates between stimuli. Since biases are generated from general stimulus processing mechanisms, they occur irrespective of species and type of signal, and it is often possible to predict the direction and intensity of the biases. One of the results from the experiments in my thesis demonstrates that similar experience in different species may generate similar biases. By giving chickens at least some of the experience of human faces as humans presumably have, the chickens subsequently expressed preferences for the same faces as a group of human subjects. Another kind of experience generated a bias for symmetry. This bias developed in the context of training chickens to recognise two mirror images of an asymmetrical stimulus. Untrained chickens and chickens trained on only one of the mirror images expressed no symmetry preferences. The bias produced by the training regime was for a specific symmetrical stimulus which had a strong resemblance to the familiar asymmetrical exemplar, rather than a general preference for symmetry. A further kind of experience, training chickens to respond to some stimuli but not to others, generated a receiver bias for exaggerated stimuli, whereas chickens trained on reversed stimuli developed a bias for less exaggerated stimuli. To investigate the potential of this bias to drive the evolution of signals towards exaggerated forms, a simplified evolutionary process was mimicked. The stimuli variants rejected by the chickens were eliminated, whereas the selected forms were kept and evolved prior to the subsequent display. As a result, signals evolved into exaggerated forms in all tested stimulus dimensions: length, intensity and area, despite the inclusion of a cost to the sender for using increasingly exaggerated signals. The bias was especially strong and persistent for stimuli varying along the intensity dimension where it remained despite extensive training. All the results in my thesis may be predicted by the receiver bias hypothesis. This implies that biases, developed due to stimuli experience, may be significant mechanisms driving the evolution of signal form.

The Evolution of Media Coverage of Historical Sports Controversies

This thesis will cover sports controversies throughout the 20th Century in the context of the media’s newspaper coverage of the events. The 1919 Black Sox Scandal, the debate over American participation in the 1936 Olympics, and Muhammad Ali’s conversion to the Nation of Islam, standing as a notorious public figure, and conscientious objection to the Vietnam War will represent the three sports controversies. The media’s adherence to cultural norms is clear in all three cases. The consistent devotion to the cultural and racial atmosphere of their respective eras was constant and helped to perpetuate accepted, mainstream cultural attitudes. Cultural and racial norms were followed in the coverage of the three discussed controversies. The anti-Semitism and racially intolerant sentiments in America during great waves of immigration in the early 1900s allowed for journalists to freely vilify Jews as corrupters of baseball and the ballplayers who were rumored to have thrown the 1919 World Series. The white ballplayers were supported in the press, who protected their own and blamed outsiders. Jim Crow and the Americanization movement forced African American and Jewish newspapers to limit their journalistic bias on both sides of the debate over American participation in the 1936 Berlin Olympics. The white, mainstream press was void of bias as the spirit of isolationism in America triumphed over journalist’s leanings in the Olympic debate. The racial tension created by the Civil Rights movement of the 1960s created an atmosphere that allowed mainstream journalists to heap endless criticism on Muhammad Ali as he gained fame. By portraying him as a villain of society as both a religious radical and traitor to America, journalists created a common enemy in the minds of white America. In all three cases, a pattern of journalists expressing the state of cultural and racial norms of the era is present and significant.

On the Evolution of the Spatial Economy with Multi-unit/Multi-plant Firms: The Impact of IT Development

This paper examines how the decline of communication costs between management and production facilities within firms and the decrease in trade costs of manufactured goods affect the spatial organization of a two-region economy with multi-unit/multi-plant firms. The development of information technology decreases the costs of communication and trade costs. Thus, the fragmentation of firms is promoted. Our result indicates that, with decreasing communication costs, firms producing low trade-cost products (such as consumer electronics) tend to concentrate their manufacturing plants in low wage countries. In contrast, firms producing high trade-cost products (such as automobiles) tend to have multiple plants serving to segmented markets, even in the absence of wage differentials.

Globalization and the Evolution of the Supply Chain: who gains and who loses?

This paper focuses on two distinct facets of globalization: the decrease in the trade costs of goods and the decline of communication costs between headquarters and production facilities within firms. When the unskilled have about the same wage in the two regions, the decrease of these costs fosters the gradual agglomeration of plants in the core region accommodating the headquarters. By contrast, when the wage gap is significant, the process of integration eventually triggers the re-location of plants into the periphery. In particular, when the process of re-location is driven by falling communication costs, the welfare of all workers living in the core goes down whereas the welfare of those who reside in the periphery rises.

The Evolution of the "One China" Concept in the Process of Taiwan's Democratization

This paper investigates how Taiwan's "one China" concept evolved during the democratization process that occurred under the leadership of former President Lee Teng-hui. The author argues that there was a crucial evolution of the "one China" concept and that the transformation of the concept resulted from changes in Taiwan's internal political circumstances. The evolution of the concept creates a real possibility that the "status quo" sought by the ROC in the Taiwan Strait both during and after the Cold War might be destroyed. In addition, any further evolution of the "one China" concept will surely make the "status quo" of Taiwan untenable, in that it would induce Taiwan to seek de jure instead of de facto independence, possibly initiating a conflict between the PRC and the ROC. To prevent such a conflict in the Taiwan Strait, the international community must persuade the ROC not to go beyond the "status quo" and to stay within the framework of de facto independence. At the same time, both the PRC and the ROC should be urged to maintain an open conduit of communication for productive talks on the reunification of China.

Evolution of GABAergic circuitry in the mammalian medial geniculate body.

Many features in the mammalian sensory thalamus, such as the types of neurons, their connections, or their neurotransmitters, are conserved in evolution. We found a wide range in the proportion of gamma-aminobutyric acidergic (GABAergic) neurons in the medial geniculate body, from <1% (bat and rat) to 25% or more (cat and monkey). In the bat, some medial geniculate body subdivisions have no GABAergic cells. Species-specific variation also occurs in the somesthetic ventrobasal complex. In contrast, the lateral geniculate body of the visual system has about the same proportion of GABAergic cells in many species. In the central auditory pathway, only the medial geniculate body shows this arrangement; the relative number of GABAergic cells in the inferior colliculus and auditory cortex is similar in each species. The range in the proportion of GABAergic neurons suggests that there are comparative differences in the neural circuitry for thalamic inhibition. We conclude that the number of GABAergic neurons in thalamic sensory nuclei may have evolved independently or divergently in phylogeny. Perhaps these adaptations reflect neurobehavioral requirements for more complex, less stereotyped processing, as in speech-like communication.

Animal visual systems and the evolution of color patterns: Sensory processing illuminates signal evolution

Animal color pattern phenotypes evolve rapidly. What influences their evolution? Because color patterns are used in communication, selection for signal efficacy, relative to the intended receiver's visual system, may explain and predict the direction of evolution. We investigated this in bowerbirds, whose color patterns consist of plumage, bower structure, and ornaments and whose visual displays are presented under predictable visual conditions. We used data on avian vision, environmental conditions, color pattern properties, and an estimate of the bowerbird phylogeny to test hypotheses about evolutionary effects of visual processing. Different components of the color pattern evolve differently. Plumage sexual dimorphism increased and then decreased, while overall (plumage plus bower) visual contrast increased. The use of bowers allows relative crypsis of the bird but increased efficacy of the signal as a whole. Ornaments do not elaborate existing plumage features but instead are innovations (new color schemes) that increase signal efficacy. Isolation between species could be facilitated by plumage but not ornaments, because we observed character displacement only in plumage. Bowerbird color pattern evolution is at least partially predictable from the function of the visual system and from knowledge of different functions of different components of the color patterns. This provides clues to how more constrained visual signaling systems may evolve.

Evolution of competing strategies in a threshold model for task allocation

A nature inspired decentralised multi-agent algorithm is proposed to solve a problem of distributed task allocation in which cities produce and store batches of different mail types. Agents must collect and process the mail batches, without global knowledge of their environment or communication between agents. The problem is constrained so that agents are penalised for switching mail types. When an agent process a mail batch of different type to the previous one, it must undergo a change-over, with repeated change-overs rendering the agent inactive. The efficiency (average amount of mail retrieved), and the flexibility (ability of the agents to react to changes in the environment) are investigated both in static and dynamic environments and with respect to sudden changes. New rules for mail selection and specialisation are proposed and are shown to exhibit improved efficiency and flexibility compared to existing ones. We employ a evolutionary algorithm which allows the various rules to evolve and compete. Apart from obtaining optimised parameters for the various rules for any environment, we also observe extinction and speciation.

Evolution of timing jitter in nonlinearly-guided, dispersion managed transmission systems

Timing jitter is a major factor limiting the performance of any high-speed, long-haul data transmission system. It arises from a number of reasons, such as interaction with accumulated spontaneous emission, inter-symbol interference (ISI), electrostriction etc. Some effects causing timing jitter can be reduced by means of non-linear filtering, using, for example, a nonlinear optical loop mirror (NOLM) [1]. The NOLM has been shown to reduce the timing jitter by suppressing the ASE and by stabilising the pulse duration [2, 3]. In this paper, we investigate the dynamics of timing jitter in a 2R regenerated system, nonlinearly guided by NOLMs at bit rates of 10, 20, 40, and 80- Gbit/s. Transmission performance of an equivalent non-regenerated (generic) system is taken as a reference.

Phylogenetic and ecological significance in the evolution of Cetacean tonal sounds

Cetaceans are aquatic mammals that rely primarily on sound for most daily tasks. A compendium of sounds is emitted for orientation, prey detection, and predator avoidance, and to communicate. Communicative sounds are among the most studied Cetacean signals, particularly those referred to as tonal sounds. Because tonal sounds have been studied especially well in social dolphins, it has been assumed these sounds evolved as a social adaptation. However, whistles have been reported in ‘solitary’ species and have been secondarily lost three times in social lineages. Clearly, therefore, it is necessary to examine closely the association, if any, between whistles and sociality instead of merely assuming it. Several hypotheses have been proposed to explain the evolutionary history of Cetacean tonal sounds. The main goal of this dissertation is to cast light on the evolutionary history of tonal sounds by testing these hypotheses by combining comparative phylogenetic and field methods. This dissertation provides the first species-level phylogeny of Cetacea and phylogenetic tests of evolutionary hypotheses of cetacean communicative signals. Tonal sounds evolution is complex in that has likely been shaped by a combination of factors that may influence different aspects of their acoustical structure. At the inter-specific level, these results suggest that only tonal sound minimum frequency is constrained by body size. Group size also influences tonal sound minimum frequency. Species that live in large groups tend to produce higher frequency tonal sounds. The evolutionary history of tonal sounds and sociality may be intertwined, but in a complex manner rejecting simplistic views such as the hypothesis that tonal sounds evolved ‘for’ social communication in dolphins. Levels of social and tonal sound complexity nevertheless correlate indicating the importance of tonal sounds in social communication. At the intraspecific level, tonal sound variation in frequency and temporal parameters may be product of genetic isolation and local levels of underwater noise. This dissertation provides one of the first insights into the evolution of Cetacean tonal sounds in a phylogenetic context, and points out key species where future studies would be valuable to enrich our understanding of other factors also playing a role in tonal sound evolution. ^

Phylogenetic and Ecological Significance in the Evolution of Cetacean Tonal Sounds

Cetaceans are aquatic mammals that rely primarily on sound for most daily tasks. A compendium of sounds is emitted for orientation, prey detection, and predator avoidance, and to communicate. Communicative sounds are among the most studied Cetacean signals, particularly those referred to as tonal sounds. Because tonal sounds have been studied especially well in social dolphins, it has been assumed these sounds evolved as a social adaptation. However, whistles have been reported in ‘solitary’ species and have been secondarily lost three times in social lineages. Clearly, therefore, it is necessary to examine closely the association, if any, between whistles and sociality instead of merely assuming it. Several hypotheses have been proposed to explain the evolutionary history of Cetacean tonal sounds. The main goal of this dissertation is to cast light on the evolutionary history of tonal sounds by testing these hypotheses by combining comparative phylogenetic and field methods. This dissertation provides the first species-level phylogeny of Cetacea and phylogenetic tests of evolutionary hypotheses of cetacean communicative signals. Tonal sounds evolution is complex in that has likely been shaped by a combination of factors that may influence different aspects of their acoustical structure. At the inter-specific level, these results suggest that only tonal sound minimum frequency is constrained by body size. Group size also influences tonal sound minimum frequency. Species that live in large groups tend to produce higher frequency tonal sounds. The evolutionary history of tonal sounds and sociality may be intertwined, but in a complex manner rejecting simplistic views such as the hypothesis that tonal sounds evolved ‘for’ social communication in dolphins. Levels of social and tonal sound complexity nevertheless correlate indicating the importance of tonal sounds in social communication. At the intraspecific level, tonal sound variation in frequency and temporal parameters may be product of genetic isolation and local levels of underwater noise. This dissertation provides one of the first insights into the evolution of Cetacean tonal sounds in a phylogenetic context, and points out key species where future studies would be valuable to enrich our understanding of other factors also playing a role in tonal sound evolution.

From Pro-Franco to Anti-Government. The Evolution of the "Sur" regarding National Politics during the Spanish Transition (1975-1978)

The Spanish transition, the political process through which Spain ceased to be a dictatorship to become a democracy, was accompanied by the dissolution of the National Movement, the institutional support for the chain of the Movement Press from its beginnings, in April 1977. This fact, among others, contributed to the /Sur/, the regional reference newspaper for the chain in Andalusia, evolving both structurally and ideologically to adapt itself to the new political regime. This study applies content analysis to editorials, articles and columns published by the newspaper between 1975 and 1978, exploring the process through which the regional newspaper edited in Málaga abandoned its propaganda function with regard to the Government, considering it undemocratic, and supported the PSOE, presenting it as the best alternative to the UCD in the Spanish Executive, thus taking on its role as a political agent.