Intersectoral size differences and migration: Kuznets revisited

The empirical evidence on the Kuznets hypothesis ranges from positive or negative support to insignificant relationships. Most studies typically try this hypothesis in domains different than the one conceived by Kuznets, which pertains to the industrialization-led urbanization (i.e., significant rural-urban migration) phase of societies. In this paper, we offer a specific channel on Kuznets' hypothesis in his suggested domain. First, we establish theoretically that intersectoral urban-rural size differences result in an intersectoral income inequality, increasing the national inequality. This, in turn, prompts an intersectoral migration, which works as an equilibriating mechanism in the economy, decreasing the inequality in due course. We then successfully test the predictions of the model. The theoretical predictions yield a recursive triangular system, in which we test, i) how the sectoral size differences influence the agricultural income, ii) how a change in agricultural income acts on migration, and iii) what happens to the income distribution as a result of migration. We find a very strong support for the theoretical predictions and the Kuznets hypothesis in its own domain.

Interspecies avian brain chimeras reveal that large brain size differences are influenced by cell-interdependent processes.

Like humans, birds that exhibit vocal learning have relatively delayed telencephalon maturation, resulting in a disproportionately smaller brain prenatally but enlarged telencephalon in adulthood relative to vocal non-learning birds. To determine if this size difference results from evolutionary changes in cell-autonomous or cell-interdependent developmental processes, we transplanted telencephala from zebra finch donors (a vocal-learning species) into Japanese quail hosts (a vocal non-learning species) during the early neural tube stage (day 2 of incubation), and harvested the chimeras at later embryonic stages (between 9-12 days of incubation). The donor and host tissues fused well with each other, with known major fiber pathways connecting the zebra finch and quail parts of the brain. However, the overall sizes of chimeric finch telencephala were larger than non-transplanted finch telencephala at the same developmental stages, even though the proportional sizes of telencephalic subregions and fiber tracts were similar to normal finches. There were no significant changes in the size of chimeric quail host midbrains, even though they were innervated by the physically smaller zebra finch brain, including the smaller retinae of the finch eyes. Chimeric zebra finch telencephala had a decreased cell density relative to normal finches. However, cell nucleus size differences between each species were maintained as in normal birds. These results suggest that telencephalic size development is partially cell-interdependent, and that the mechanisms controlling the size of different brain regions may be functionally independent.

Size differences in the Dufour gland of Apis mellifera Linnaeus (Hymenoptera, Apidae) between and within the female castes

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

Caste Differences in Polybia emaciata, a Mud-Nesting Eusocial Wasp (Hymenoptera: Vespidae), that Bear on Pre-Imaginal Determination but not Size Differences

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

Caste differences in Polybia ematiata, a mud-nesting eusocial wasp (hymenoptera: Vespidae), that bear on pre-imaginal determination but not size differences

The Epiponini is a group of social wasps living in polygynic societies. The caste dimorphism varies from incipient to well distinct. Morphometric analyses on twelve body parts and ovarian development of Polybia emaciata Lucas 1879, were used to estimate the level of caste differentiation in seven colonies. Physiologic differences were found. Among queens the ovaries were inseminated and presented as highly developed; in intermediate females, ovaries were slightly developed and uninseminated, and for the workers the ovaries were not developed or inseminated. In addition, the coloration of the mesosoma and metasoma were darker in workers and intermediates. Morphometric analysis evidenced slight morphological differences. Even though body proportions were not enough to discriminate castes, the fifth sternite of the gaster had important characters that were able to differentiate queens from workers and intermediates. We propose that P. emaciata presents a case of pre-imaginal caste determination, which is not strictly based on size.

Shape differences rather than size differences between castes in the Neotropical swarm-founding wasp Metapolybia docilis (Hymenoptera: Vespidae, Epiponini)

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.

Robust dielectric properties of B-site size-disordered hexagonal Ln(2)CuTiO(6) (Ln = Y, Dy, Ho, Er, and Yb)

Hexagonal Ln(2)CuTiO(6) (Ln = Y, Dy, Ho, Er, and Yb) exhibits a rare combination of interesting dielectric properties, in the form of relatively large dielectric constants (epsilon' > 30), low losses, and extremely small temperature and frequency dependencies, over large ranges of temperature and frequency Choudhury et al., Appl. Phys. Lett. 96, 162903 (2010) and Choudhury et al., Phys. Rev. B 82, 134203 (2010)], making these compounds promising as high-k dielectric materials. The authors present a brief review of the existing literature on this interesting class of oxides, complimenting it with spectroscopic data in conjunction with first-principles calculation results, revealing a novel mechanism underlying these robust dielectric properties. These show that the large size differences in Cu2+ and Ti4+ at the B-site, aided by an inherent random distribution of CuO5 and TiO5 polyhedral units, frustrates the ferroelectric instability, inherent to the noncentrosymmetric P6(3) cm space group of this system, and gives rise to the observed relatively large dielectric constant values. Additionally, the phononic contributions to the dielectric constant are dominated primarily by mid-frequency (>100 cm(-1)) polar modes, involving mainly Ti4+ 3d(0) ions. In contrast, the soft polar phonon modes with frequencies typically less than 100 cm(-1), usually responsible for dielectric properties of materials, are found to be associated with non-d(0) Cu2+ ions and to contribute very little, giving rise to the remarkable temperature stability of dielectric properties of these compounds. (C) 2014 American Vacuum Society.

Mainland size variation informs predictive models of exceptional insular body size change in rodents.

The tendency for island populations of mammalian taxa to diverge in body size from their mainland counterparts consistently in particular directions is both impressive for its regularity and, especially among rodents, troublesome for its exceptions. However, previous studies have largely ignored mainland body size variation, treating size differences of any magnitude as equally noteworthy. Here, we use distributions of mainland population body sizes to identify island populations as 'extremely' big or small, and we compare traits of extreme populations and their islands with those of island populations more typical in body size. We find that although insular rodents vary in the directions of body size change, 'extreme' populations tend towards gigantism. With classification tree methods, we develop a predictive model, which points to resource limitations as major drivers in the few cases of insular dwarfism. Highly successful in classifying our dataset, our model also successfully predicts change in untested cases.

Energetics and litter size variation in domestic dog Canis familiaris breeds of two sizes

We measured resting metabolic rate (RMR), daily energy expenditure (DEE) and metabolisable energy intake (MEI) in two breeds of dog during peak lactation to test whether litter size differences were a likely consequence of allometric variation in energetics. RMR of Labrador retrievers (30 kg, n = 12) and miniature Schnauzers (6 kg, n = 4) averaged 3437 and 1062 kJ/day, respectively. DEE of Labradors (n = 6) and Schnauzers (n = 4) averaged 9808 and 2619 kJ/day, respectively. MEI of Labradors (n = 12) was 22448 kJ/day and of Schnauzers (a = 7) was 5382 kJ/day. DEE of Labrador pups (2.13 kg, n = 19) was 974 kJ/day and Schnauzers (0.89 kg, n = 7) were 490 kJ/day. Although Labradors had higher MEIs than Schnauzers during peak lactation, there was no difference in mass-specific energy expenditure between the two breeds. Hence, it is unlikely that litter size variation is a likely consequence of differences in maternal energy expenditure. Individual offspring were relatively more costly for mothers of the smaller breed to produce. Therefore, litter size variations were consistent with the expectation that smaller offspring should be more costly for mothers, but not that smaller mothers should per se invest more resources in reproduction. (C) 2001 Elsevier Science Inc. All rights reserved.

Large body size for winning and large swords for winning quickly in swordtail males, Xiphophorus helleri

Contestants can either assess their own resource-holding potential relative to their opponent (mutual assessment) or rely solely on the assessment of their own fighting ability (self-assessment). To discriminate between these possibilities, we staged dyadic territorial contests between 'size-matched' male swordtails. These contests consist of a combination of ritualized displays and direct fighting. Although size differences were small, winners were larger than losers and smaller fish tended to be winners only when the size difference was negligible. Body size, however, did not influence contest duration and there was no increase in contest duration with mean body size; thus, there is no support for self-assessment in these animals. We also examined the effects of the sword, which comprises a sexually selected extension used in female choice that reduces swimming efficiency but increases acceleration. The length of the sword (adjusted for body size) did not differ between winners and losers; however, losers conceded earlier if the opponent had a large sword for its body size but this decision was independent of the loser's own sword length. Losers thus assessed the swords of winners, which precludes self-assessment; however, because winners appeared not to assess the swords of losers, this does not fully support the idea of mutual assessment. (c) 2008 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.

Size variation in the grapsid crab Aratus pisonii (H. Milne-Edwards, 1837) among populations of different subtropical mangroves

Size variation in the adult population of the grapsid crab Aratus pisonii (H. Milne-Edwards, 1837) was studied by comparing median values obtained from six different populations from nearby mangrove areas. The mangrove structure at those sites was also examined and related to size differences among populations. Disregarding sex, crab size is apparently related to the mangrove structure. Smallest and largest crab sizes were recorded at the sites where tree density and tree diameter were minimum and maximum, respectively. Estimates of size at the onset of maturity, considering the size of the smallest ovigerous female, followed the same trend. These results support the hypothesis that average crab size and size at the onset of maturity can be associated to mangrove productivity.

Temporal and morphological differences in post-embryonic differentiation of the mushroom bodies in the brain of workers, queens, and drones of Apis mellifera (Hymenoptera, Apidae)

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