265 resultados para caste


Relevância:

10.00% 10.00%

Publicador:

Resumo:

Complementary sex determination in Hymenoptera implies that heterozygosity at the sex locus leads to the development of diploid females, whereas hemizygosity results in haploid males. Diploid males can arise through inbreeding. In social species, these pose a double burden on colony fitness, from significant reduction in its worker force and through being less viable and fertile than haploid males. Apart from being "misfits", diploid males are of interest to assess molecular correlates for possibly ploidy-related bionomic differences. Herein, we generated suppression subtractive cDNA libraries from newly emerged haploid and diploid males of the stingless bee Melipona quadrifasciata to enrich for differentially expressed genes. Gene Ontology classification revealed that in haploid males more DEGs were related to stress responsiveness, biosynthetic processes, reproductive processes and spermatogenesis, whereas in diploid ones differentially expressed genes were associated with cellular organization, nervous system development and amino acid transport were prevalent. Furthermore, both libraries contained over 40 % ESTs representing possibly novel transcripts. Quantitative RT-PCR analyses confirmed the differential expression of a representative DEG set in newly emerged males. Several muscle formation and energy metabolism-related genes were under-expressed in diploid males. On including 5-day-old males in the analysis, changes in transcript abundance during sexual maturation were revealed.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Beyond the physiological and behavioural, differences in appendage morphology between the workers and queens of Apis mellifera are pre-eminent. The hind legs of workers, which are highly specialized pollinators, deserve special attention. The hind tibia of worker has an expanded bristle-free region used for carrying pollen and propolis, the corbicula. In queens this structure is absent. Although the morphological differences are well characterized, the genetic inputs driving the development of this alternative morphology remain unknown. Leg phenotype determination takes place between the fourth and fifth larval instar and herein we show that the morphogenesis is completed at brown-eyed pupa. Using results from the hybridization of whole genome-based oligonucleotide arrays with RNA samples from hind leg imaginal discs of pre-pupal honeybees of both castes we present a list of 200 differentially expressed genes. Notably, there are castes preferentially expressed cuticular protein genes and members of the P450 family. We also provide results of qPCR analyses determining the developmental transcription profiles of eight selected genes, including abdominal-A, distal-less and ultrabithorax (Ubx), whose roles in leg development have been previously demonstrated in other insect models. Ubx expression in workers hind leg is approximately 25 times higher than in queens. Finally, immunohistochemistry assays show that Ubx localization during hind leg development resembles the bristles localization in the tibia/basitarsus of the adult legs in both castes. Our data strongly indicate that the development of the hind legs diphenism characteristic of this corbiculate species is driven by a set of caste-preferentially expressed genes, such as those encoding cuticular protein genes, P450 and Hox proteins, in response to the naturally different diets offered to honeybees during the larval period.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Until now, the Neotropical termite genus Cyranotermes was known from three species: C. timuassu Araujo, C. glaber Constantino, and C. caete Cancello. In this paper a new species, Cyranotermes karipuna, n. sp., is described and illustrated from imago, worker, and soldier castes, along with its nest. It is also provided an illustrated identification key to species of Cyranotermes, a map with the occurrence of all species, and the first description of the imago caste of Cyranotermes, based on the first description of the imago of C. timuassu, and the imago of the new species.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

We present a comprehensive phylogenetic analysis of Syntermitinae, including representatives of all genera of the subfamily, along with all 12 species assigned formerly to the genus Armitermes Wasmann (Termitidae, Syntermitinae), and 4 new species described herein. Syntermitinae was recovered as a natural group and the hypothesis that the frontal tube indicates convergence between Syntermitinae and Nasutitermitinae was corroborated. Also, several diagnostic characters proposed in the original description of Syntermitinae are discussed. Alongside the phylogenetic study, a taxonomic revision of the Neotropical genus Armitermes was carried out, resulting in division of the genus into four genera. Taxonomic novelties are: Armitermes now includes A. armiger (Motschulsky), A. bidentatus Rocha & Cancello sp.n. and A. spininotus Rocha & Cancello sp.n.; Silvestritermes Rocha & Cancello gen.n. includes S. euamignathus (Silvestri) comb.n., S. lanei (Canter) comb.n., S. gnomus (Constantino) comb.n., S. duende Rocha & Cancello sp.n., S. minutus (Emerson) comb.n., S. almirsateri Rocha & Cancello sp.n. and S. holmgreni (Snyder) comb.n.; Uncitermes Rocha & Cancello gen.n. includes U. teevani (Emerson) comb.n.; Mapinguaritermes Rocha & Cancello gen.n. includes M. peruanus (Holmgren) comb.n. and M. grandidens (Emerson) comb.n. A new synonymy is proposed for A. cerradoensis Mathews under S. euamignathus. All soldiers are described and illustrated, as are the mandibles and digestive tract of the worker and the imago caste, when available. We provide a dichotomous key, based on soldiers, for all genera of Syntermitinae, and distribution maps and dichotomous keys, based on soldiers, for the species of Armitermes and all the new genera described herein.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Abstract Background Swarm-founding epiponine wasps are an intriguing group of social insects in which colonies are polygynic (several queens share reproduction) and differentiation between castes is often not obvious. However, caste differences in some may be more pronounced in later phases of the colony cycle. Results Using morphometric analyses and multivariate statistics, it was found that caste differences in Metapolybia docilis are slight but more distinct in latter stages of the colony cycle. Conclusions Because differences in body parts are so slight, it is proposed that such variation may be due to differential growth rates of body parts rather than to queens being larger in size, similar to other previously observed epiponines.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

This dissertation explores how diseases contributed to shape historical institutions and how health and diseases are still affecting modern comparative development. The overarching goal of this investigation is to identify the channels linking geographic suitability to diseases and the emergence of historical and modern insitutions, while tackling the endogenenity problems that traditionally undermine this literature. I attempt to do so by taking advantage of the vast amount of newly available historical data and of the richness of data accessible through the geographic information system (GIS). The first chapter of my thesis, 'Side Effects of Immunities: The African Slave Trade', proposes and test a novel explanation for the origins of slavery in the tropical regions of the Americas. I argue that Africans were especially attractive for employment in tropical areas because they were immune to many of the diseases that were ravaging those regions. In particular, Africans' resistance to malaria increased the profitability of slaves coming from the most malarial parts of Africa. In the second chapter of my thesis, 'Caste Systems and Technology in Pre-Modern Societies', I advance and test the hypothesis that caste systems, generally viewed as a hindrance to social mobility and development, had been comparatively advantageous at an early stage of economic development. In the third chapter, 'Malaria as Determinant of Modern Ethnolinguistic Diversity', I conjecture that in highly malarious areas the necessity to adapt and develop immunities specific to the local disease environment historically reduced mobility and increased isolation, thus leading to the formation of a higher number of different ethnolinguistic groups. In the final chapter, 'Malaria Risk and Civil Violence: A Disaggregated Analysis for Africa', I explore the relationship between malaria and violent conflicts. Using georeferenced data for Africa, the article shows that violent events are more frequent in areas where malaria risk is higher.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Drawing on ethnographic research and employing a micro-historical approach that recognizes not only the transnational but also the culturally specific manifestations of modernity, this article centers on the efforts of a young woman to negotiate shifting and conflicting discourses about what a good life might consist of for a highly educated and high caste Hindu woman living at the margins of a nonetheless globalized world. Newly imaginable worlds in contemporary Mithila,South Asia, structure feeling and action in particularly gendered and classed ways, even as the capacity of individuals to actualize those worlds and the “modern” selves envisioned within them are constrained by both overt and subtle means. In the context of shifting cultural anchors, new practices of silence, literacy, and even behaviors interpreted as “mental illness” may become tactics in an individual’s negotiation of conflicting self-representations. The confluence of forces at play in contemporary Mithila, moreover, is creating new structures of feeling that may begin to reverse long-standing locally held assumptions about strong solidarities between natal families and daughters, on the one hand, and weak solidarities between affinal families and new daughters-in-law, on the other.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

In honeybees (Apis niellifera), the process of nectar collection is considered a straightforward example of task partitioning with two subtasks or two intersecting cycles of activity: (1) foraging and (2) storing of nectar, linked via its transfer between foragers and food processors. Many observations suggest, however, that nectar colleclion and processing in honeybees is a complex process, involving workers of other sub-castes and depending on variables such as resource profitability or the amount of stored honey. It has been observed that food processor bees often distribute food to other hive bees after receiving it from incoming foragers, instead of storing it immediately in honey cells. While there is little information about the sub-caste affiliation and the behaviour of these second-order receivers, this stage may be important for the rapid distribution of nutrients and related information. To investigate the identity of these second-order receivers, we quantified behaviours following nectar transfer and compared these behaviours with the behaviour of average worker hive-bees. Furthermore, we tested whether food quality (sugar concentration) affects the behaviour of the second-order receivers. Of all identified second-order receivers, 59.3% performed nurse duties, 18.5% performed food-processor duties and 22.2% performed forager duties. After food intake, these bees were more active, had more trophallaxes (especially offering contacts) compared to average workers and they were found mainly in the brood area, independent of food quality. Our results show that the liquid food can be distributed rapidly among many bees of the three main worker sub-castes, without being stored in honey cells first. Furthermore, the results suggest that the rapid distribution of food partly depends on the high activity of second-order receivers.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The political philosophy underpinning the Indian Constitution is socialist economy in a multilingual political landscape. The Constitution grants some fundamental rights to all citizens regarding language and to linguistic and other minorities regarding education. It also obligates states to use many languages in school education. Restructuring the economy with free market as its pivot and the growing dominance of English in the information driven global economy give rise to policy changes in language use in education, which undermine the Constitutional provisions relating to language, though these changes reflect the manufactured consent of the citizens. This is made possible by the way the Constitution is interpreted by courts with regard to the fundamental rights of equality and non-discrimination when they apply to language. The unique property of language that it can be acquired, unlike other primordial attributes such as ethnicity or caste, comes into play in this interpretation. The result is that the law of the market takes over the law of the land.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

This paper examines the factors that prevent slum children aged 5 to 14 from gaining access to schooling in light of the worsening urban poverty and sizable increase in rural-to-urban migration. Bias against social disadvantage in terms of gender and caste is not clearly manifested in schooling, while migrated children are less likely to attend school. I argue that the lack of preparation for schooling in the pre-schooling ages and school admission procedures are the main obstacles for migrated children. The most important implication for universal elementary education in urban India is raising parental awareness and simplifying the admission procedures.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The informal economy is a very important sector of the Indian economy. The National Council of Applied Economic Research estimates that the informal sector - "unorganised sector" - generates about 62% of GDP and provides for about 55% of total employment (ILO 2002, p. 14). This paper studies the characteristics of the workers in the informal economy and whether internal migrants treat this sector as a temporary location before moving on to the organised or formal sector to improve their lifetime income and living conditions. We limit our study to the Indian urban (non-agricultural) sector and study the characteristics of the household heads that belong to the informal sector (self-employed and informal wage workers) and the formal sector. We find that household heads that are less educated, come from poorer households, and/or are in lower social groups (castes and religions) are more likely to be in the informal sector. In addition, our results show strong evidence that the longer a rural migrant household head has been working in the urban sector, ceteris paribus, the more likely that individual has moved out of the informal wage sector. These results support the hypothesis that, for internal migrants, the informal wage labour market is a stepping stone to a better and more certain life in the formal sector.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

India's Muslim community, which accounts for 14.4 percent of India’s vast population and is thus the largest of all religious minorities, has been the subject of considerable development discourse as Muslims have the lowest level of educational attainment and standard of living among socio-religious groups in the country. This study addresses the meaning of education and career opportunities for Muslim youths in relation to their educational credentials and social position in the hierarchy of Muslim class and caste groups, with particular reference to a community in Uttar Pradesh. The author contends that the career opportunities, possibilities, and strategies of Muslim youths in Indian society depend on multiple factors: social hierarchy, opportunities to utilize economic resources, social networks, cultural capital, and the wider structural disparities within which the Muslims are situated and wherein they question the value of higher education in gaining them admission to socially recognized and established employment sectors.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The life history of Harpegnathos saltator is exceptional among ants because both queens and workers reproduce sexually. Recently mated queens start new colonies alone, but later some of the offspring workers also become inseminated and take over the egg-laying role. This alternation seems associated with the existence of very complex underground nests, which are designed to survive floods. Longevity of ponerine queens is low (a consequence of limited caste dimorphism in this "primitive" subfamily), and upon the death of an H. saltator foundress, the nest represents a substantial investment. The queen's progeny should thus be strongly selected to retain the valuable nests. Unlike the flying queens, the workers copulate with males from their own colonies, and, thus, their offspring are expected to be highly related to the foundress. Colony fission appears not to occur because a daughter fragment would lack an adequate nest for protection. Thus, the annual production of queens in colonies with reproductive workers remains essential for the establishment of new colonies. This contrasts with various other ponerine species in which the queens no longer exist.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Supreme Court precedent establishes that the government may not punish children for matters beyond their control. Same-sex marriage bans and non-recognition laws (“marriage bans”) do precisely this. The states argue that marriage is good for children, yet marriage bans categorically exclude an entire class of children – children of same-sex couples – from the legal, economic and social benefits of marriage. This amicus brief recounts a powerful body of equal protection jurisprudence that prohibits punishing children to reflect moral disapproval of parental conduct or to incentivize adult behavior. We then explain that marriage bans punish children of same-sex couples because they: 1) foreclose their central legal route to family formation; 2) categorically void their existing legal parent-child relationships incident to out-of-state marriages; 3) deny them economic rights and benefits; and 4) inflict psychological and stigmatic harm. States cannot justify marriage bans as good for children and then exclude children of same-sex couples based on moral disapproval of their same-sex parents’ relationships or to incentivize opposite-sex couples to “procreate” within the bounds of marriage. To do so, severs the connection between legal burdens and individual responsibility and creates a permanent class or caste distinction.