The Evolution of Larger Size in High Altitude Drosophila melanogaster has a Variable Genetic Architecture

Important uncertainties persist regarding the genetic architecture of adaptive trait evolution in natural populations, including the number of genetic variants involved, whether they are drawn from standing genetic variation, and whether directional selection drives them to complete fixation. Here, we take advantage of a unique natural population of Drosophila melanogaster from the Ethiopian highlands, which has evolved larger body size than any other known population of this species. We apply a bulk segregant quantitative trait locus (QTL) mapping approach to four unique crosses between highland Ethiopian and lowland Zambian populations for both thorax length and wing length. Results indicated a persistently variable genetic basis for these evolved traits (with largely distinct sets of QTLs for each cross), and at least a moderately polygenic architecture with relatively strong effects present. We complemented these mapping experiments with population genetic analyses of QTL regions and gene ontology enrichment analysis, generating strong hypotheses for specific genes and functional processes that may have contributed to these adaptive trait changes. Finally, we find that the genetic architectures our QTL mapping results for size traits mirror those from similar experiments on other recently-evolved traits in this species. Collectively, these studies suggest a recurring pattern of polygenic adaptation in this species, in which causative variants do not approach fixation and moderately strong effect loci are present.

The Evolution of Larger Size in High Altitude Drosophila melanogaster has a Polymorphic Genetic Architecture

Important uncertainties persist regarding the genetic architecture of adaptive trait evolution in natural populations, including the number of genetic variants involved, whether they are drawn from standing genetic variation, and whether directional selection drives them to complete fixation. Here, we take advantage of a unique natural population of Drosophila melanogaster from the Ethiopian highlands, which has evolved larger body size than any other known population of this species. We apply a bulk segregant quantitative trait locus (QTL) mapping approach to four unique crosses between highland Ethiopian and lowland Zambian populations for both thorax length and wing length. Results indicated a persistently variable genetic basis for these evolved traits (with largely distinct sets of QTLs for each cross), and at least a moderately polygenic architecture with relatively strong effects present. We complemented these mapping experiments with population genetic analyses of QTL regions and gene ontology enrichment analysis, generating strong hypotheses for specific genes and functional processes that may have contributed to these adaptive trait changes. Finally, we find that the genetic architectures our QTL mapping results for size traits mirror those from similar experiments on other recently-evolved traits in this species. Collectively, these studies suggest a recurring pattern of polygenic adaptation in this species, in which causative variants do not approach fixation and moderately strong effect loci are present.

Honeybee (Apis mellifera) Maternal Effect Causes Alternation of DNA Methylation Regulating Queen Development

Queen-worker caste dimorphism is a typical trait for honeybees (Apis mellifera). We previously showed a maternal effect on caste differentiation and queen development, where queens emerged from queen-cell eggs (QE) had higher quality than queens developed from worker cell eggs (WE). In this study, newly-emerged queens were reared from QE, WE, and 2-day worker larvae (2L). The thorax size and DNA methylation levels of queens were measured. We found that queens emerging from QE had significantly larger thorax length and width than WE and 2L. Epigenetic analysis showed that QE/2L comparison had the most different methylated genes (DMGs, 612) followed by WE/2L (473), and QE/WE (371). Interestingly, a great number of DMGs (42) were in genes belonging to mTOR, MAPK, Wnt, Notch, Hedgehog, FoxO, and Hippo signaling pathways that are involved in regulating caste differentiation, reproduction and longevity. This study proved that honeybee maternal effect causes epigenetic alteration regulating caste differentiation and queen development.

Sex Ratio and Growth Pattern of Coconut Crabs Birgus latro (Crustacea, Decapoda, Cianobitidae) in North Moluccas Province, Indonesia

Coconut crab (Birgus latro) is a crustacean that has a large size until four kilograms. The study aimed to analyze sex ratio and growth pattern including the relationship of thorax length - body weight, thorax width - body weight and cephalothorax length plus rostrum - body weight in Daeo (Morotai Island), Laigoma (South Halmahera District) and Fitako (North Halmahera District). The sex ratio was determined using χ2 test and the growth pattern was tested by the b value through t test. The results showed sex ratio of 1: 0.9 in Daeo (n = 581), 1: 0.6 in Laigoma (n = 24), and 1: 2 in Fitako (n = 31). The relationship of thorax length, thorax width and cephalothorax length plus rostrum with body weight were strongly correlated (R2> 70%). The growth pattern of coconut crab in Daeo was negative allometric, while in Laigoma and Fitako were negative allometric and isometric.

Morphometric measurements of sheep fed with increasing levels of sunflower meal

The objective of this work was to evaluate the performance, body morphometric measurements and testicular development in lambs fed with different rates of sunflower meal inclusion. The animals (24) were randomly distributed in treatments with 0, 10, 20 and 30% of sunflower meal in the dry matter of the diet, in six replicates, during 56 days of confinement. The addition of the coproduct at increasing dietary rates increased linearly the dry matter intake in the percentage of live weight and neutral detergent fiber. Despite this, there was a linear reduction in ether extract intake and chest width. On the other hand, there was no difference in daily, total and final weight gains. The body condition score; height of withers, croup and thorax; length of body and croup; width of fore croup, hind croup and chest; thoracic and neck diameters also did not change with the addition of the coproduct. The testicular measures 26.76; 6.11; 6.08; 5.22; 5.21; 4.80, and 4.81cm varied quadratically with the inclusion. Therefore, the inclusion of 30% of the coproduct changes nutrient intake and testicular biometry, but does not interfere in the body weight and development, being an economical alternative.

Effects of Queen Cell Size and Caging Days of Mother Queen on Rearing Young Honey Bee Queens Apis mellifera L.

This study aims to investigate the effect of queen cell size (9.4 mm, 9.6 mm, 9.8 mm and 10.0 mm) and mother queen caged time (0 day, 2 days and 4 days) on rearing young queens without grafting larvae. The birth weight, ovarian tubes, thorax length and width were significantly increased with the increasing diameter of queen cell size. The expression level of Vitellogenin (Vg) in young queen ovaries was also up-regulated with the increased queen cell size diameter. These results indicate that the queen cell size can strongly affect the rearing queen quality and reproductive ability. Moreover, the weight, length and width of laying eggs rose with the mother queen caging time, and young queens reared with the hatched larvae from these eggs were also increased in terms of birth weight, ovarian tubes, thorax length and width. Furthermore, the expression level of Vg in reared queen ovaries was also up-regulated with the caged time. These results reveal that the caged time of queens could significantly influence egg size and their relative queen quality.

The Effects of Age and Number of Grafted Larvae on Some Physical Characteristics of Queen Bees and Acceptance Rate of Queen Bee Cell

This study was carried out to determine the effects of age and number of grafted larvae on acceptance rates, body weight, body length, head width and length, thorax width and length, and wing width and length of queen bees. One breeding and eleven starter hives were used for rearing queen bees. Totally, 495 one, two, and three-day-old larvae were grafted into starter hives comprising 30, 45, and 60 and 414 larvae were accepted; thus, generally, the acceptance rate was calculated as 83%. The best acceptance rate was calculated in three-day-old larvae group as 85.15%. There were found a statistically significant effect of the number of grafted larvae on body length and head width of queen. However, there were any effects on weight, head length, thorax width, thorax length, wing width, wing length, and acceptance rate of larvae. Age of grafted larvae did not have a statistically significant effect on head width, head length, wing width and acceptance rate of larvae. On the other hand, age of grafted larvae had a statistically significant effect on queen weight, body length, thorax width and length, and wing length of queen. If bee breeders wish to improve their stock, they should graft one-day-old larvae for rearing better queen bees.

Evidence for variations in the morphometric traits between two sibling species of Drosophila: D. ananassae and D. pallidosa

Darwinian theory of evolution states that, evolution occurs through the natural selection. Therefore, demonstration of natural selection in nature is the central aim of many evolutionary studies and selection acts primarily at the phenotypic level because it is well known that phenotypic traits are the primary target of natural selection. While keeping this in view, we have studied certain morphometric traits in the sibling species pair, D. ananassae and D. pallidosa to test intra- and interspecific variations. The traits studied are wing length, thorax length, ratio of wing length and thorax length, sternopleural bristle number, ovariole number and sex-comb tooth number. In females of D. ananassae, significant strain differences were found for all the traits except ovariole number. In males, significant strain differences were found for all the traits. On the other hand, in D. pallidosa, significant strain differences were found for all the traits in both, males and females. The values of all the morphometric traits were significantly higher in females of both the species in comparison to males. The values of all the morphometric traits were higher in D. ananassae. However, the phenotypic variability, expressed in terms of coefficient of variation, was higher in D. pallidosa. Except for ratio of wing length and thorax length, CV was higher in the case of females in comparison to males. Size related traits are least variable while bristle numbers and reproductive traits are most variable. Except few, most of the traits are positively correlated with each other in both the species. Intra- and interspecific variations were found with respect to different morphometric traits. Although sibling species have been defined as morphologically identical, our results show that sibling species may show variations in certain morphometric traits and these quantitative differences in the morphometric traits act as discriminant marker between these sibling species in the lack of any qualitative differences.