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\"All living things reproduce, and they pass on inherited traits to their offspring. This book explores the different ways that plants and animals produce offspring, and how they pass on traits from one generation to the next.\"--Amazon.com.

Tsetse flies are the sole vectors of human African trypanosomiasis throughout sub-Saharan Africa. Both sexes of adult tsetse feed exclusively on blood and contribute to disease transmission. Notable differences between tsetse and other disease vectors include obligate microbial symbioses, viviparous reproduction, and lactation. Here, we describe the sequence and annotation of the 366-megabase Glossina morsitans morsitans genome. Analysis of the genome and the 12,308 predicted protein–encoding genes led to multiple discoveries, including chromosomal integrations of bacterial (Wolbachia) genome sequences, a family of lactation-specific proteins, reduced complement of host pathogen recognition proteins, and reduced olfaction/chemosensory associated genes. These genome data provide a foundation for research into trypanosomiasis prevention and yield important insights with broad implications for multiple aspects of tsetse biology.

Reviews the fundamental concepts of reproduction and how genetic information determines the physical characteristics of an organism.

Here we report the genome sequence of the honeybee Apis mellifera, a key model for social behaviour and essential to global ecology through pollination. Compared with other sequenced insect genomes, the A. mellifera genome has high A+T and CpG contents, lacks major transposon families, evolves more slowly, and is more similar to vertebrates for circadian rhythm, RNA interference and DNA methylation genes, among others. Furthermore, A. mellifera has fewer genes for innate immunity, detoxification enzymes, cuticle-forming proteins and gustatory receptors, more genes for odorant receptors, and novel genes for nectar and pollen utilization, consistent with its ecology and social organization. Compared to Drosophila, genes in early developmental pathways differ in Apis, whereas similarities exist for functions that differ markedly, such as sex determination, brain function and behaviour. Population genetics suggests a novel African origin for the species A. mellifera and insights into whether Africanized bees spread throughout the New World via hybridization or displacement.

Comparative analysis of multiple genomes in a phylogenetic framework dramatically improves the precision and sensitivity of evolutionary inference, producing more robust results than single-genome analyses can provide. The genomes of 12 Drosophila species, ten of which are presented here for the first time (sechellia, simulans, yakuba, erecta, ananassae, persimilis, willistoni, mojavensis, virilis and grimshawi), illustrate how rates and patterns of sequence divergence across taxa can illuminate evolutionary processes on a genomic scale. These genome sequences augment the formidable genetic tools that have made Drosophila melanogaster a pre-eminent model for animal genetics, and will further catalyse fundamental research on mechanisms of development, cell biology, genetics, disease, neurobiology, behaviour, physiology and evolution. Despite remarkable similarities among these Drosophila species, we identified many putatively non-neutral changes in protein-coding genes, non-coding RNA genes, and cis-regulatory regions. These may prove to underlie differences in the ecology and behaviour of these diverse species.

Alcohol use is correlated within spouse-pairs, but it is difficult to disentangle effects of alcohol consumption on mate-selection from social factors or the shared spousal environment. We hypothesised that genetic variants related to alcohol consumption may, via their effect on alcohol behaviour, influence mate selection. Here, we find strong evidence that an individual’s self-reported alcohol consumption and their genotype at rs1229984, a missense variant in ADH1B , are associated with their partner’s self-reported alcohol use. Applying Mendelian randomization, we estimate that a unit increase in an individual’s weekly alcohol consumption increases partner’s alcohol consumption by 0.26 units (95% C.I. 0.15, 0.38; P  = 8.20 × 10 −6 ). Furthermore, we find evidence of spousal genotypic concordance for rs1229984, suggesting that spousal concordance for alcohol consumption existed prior to cohabitation. Although the SNP is strongly associated with ancestry, our results suggest some concordance independent of population stratification. Our findings suggest that alcohol behaviour directly influences mate selection. From observational studies, alcohol consumption behaviours are known to be correlated in spouses. Here, Howe et al. use partners’ genotypic information in a Mendelian randomization framework and show that a SNP in the ADH1B gene associates with partner’s alcohol consumption, suggesting that alcohol consumption affects mate choice.

Sexual reproduction can lead to major conflicts between sexes and within genomes1, 2, 3, 4. Here we report an extreme case of such conflicts in the little fire ant Wasmannia auropunctata. We found that sterile workers are produced by normal sexual reproduction, whereas daughter queens are invariably clonally produced. Because males usually develop from unfertilized maternal eggs in ants and other haplodiploid species, they normally achieve direct fitness only through diploid female offspring. Hence, although the clonal production of queens increases the queen's relatedness to reproductive daughters, it potentially reduces male reproductive success to zero. In an apparent response to this conflict between sexes, genetic analyses reveal that males reproduce clonally, most likely by eliminating the maternal half of the genome in diploid eggs. As a result, all sons have nuclear genomes identical to those of their father. The obligate clonal production of males and queens from individuals of the same sex effectively results in a complete separation of the male and female gene pools. These findings show that the haplodiploid sex-determination system provides grounds for the evolution of extraordinary genetic systems and new types of sexual conflict

PREMISE OF THE STUDY: Hybridization between diploids and tetraploids can lead to new allopolyploid species, often via a triploid intermediate. Viable triploids are often produced asymmetrically, with greater success observed for \"maternal-excess\" crosses where the mother has a higher ploidy than the father. Here we investigated the evolutionary origins of Mimulus peregrinus, an allohexaploid recently derived from the triploid M. xrobertsii, to determine whether reproductive asymmetry has shaped the formation of this new species. METHODS: We used reciprocal crosses between the diploid (M. guttatus) and tetraploid (M. luteus) progenitors to determine the viability of triploid M. xrobertsii hybrids resulting from paternal- vs. maternal-excess crosses. To investigate whether experimental results predict patterns seen in the field, we performed parentage analyses comparing natural populations of M. peregrinus to its diploid, tetraploid, and triploid progenitors. Organellar sequences obtained from pre-existing genomic data, supplemented with additional genotyping was used to establish the maternal ancestry of multiple M. peregrinus and M. xrobertsii populations. KEY RESULTS: We found strong evidence for asymmetric origins of M. peregrinus, but opposite to the common pattern, with paternal-excess crosses significantly more successful than maternal-excess crosses. These results successfully predicted hybrid formation in nature: 111 of 114 M. xrobertsii individuals, and 27 of 27 M. peregrinus, had an M. guttatus maternal haplotype. CONCLUSION: This study, which includes the first Mimulus chloroplast genome assembly, demonstrates the utility of parentage analysis through genome skimming. We highlight the benefits of complementing genomic analyses with experimental approaches to understand asymmetry in allopolyploid speciation.

The bad side of a good gene The unique long-term study of the red deer populations on the Isle of Rum, off the west coast of Scotland, has revealed the existence of sexually antagonistic fitness variation in a long-lived, sexually-dimorphic species in the wild. The finding proves what has been expected from theory and recent Drosophila laboratory experiments: genes that make a good male do not necessarily make a good female, and vice versa. The consequence of this effect is the selection against males that carry genes for high female fitness, which may have profound effects on the selection and maintenance of genetic variation in natural populations. Use of a long-term data set demonstrates the existence of sexually antagonistic fitness variation in a long-lived, sexually-dimorphic species in the wild — genes that make a good male do not make a good female, and vice versa. This sexually antagonistic effect results in selection against males that carry genes for high female fitness. Evolutionary theory predicts the depletion of genetic variation in natural populations as a result of the effects of selection, but genetic variation is nevertheless abundant for many traits that are under directional or stabilizing selection 1 . Evolutionary geneticists commonly try to explain this paradox with mechanisms that lead to a balance between mutation and selection 2 . However, theoretical predictions of equilibrium genetic variance under mutation–selection balance are usually lower than the observed values, and the reason for this is unknown 3 . The potential role of sexually antagonistic selection in maintaining genetic variation has received little attention in this debate, surprisingly given its potential ubiquity in dioecious organisms. At fitness-related loci, a given genotype may be selected in opposite directions in the two sexes. Such sexually antagonistic selection will reduce the otherwise-expected positive genetic correlation between male and female fitness 4 . Both theory 5 , 6 , 7 and experimental data 8 , 9 , 10 , 11 , 12 suggest that males and females of the same species may have divergent genetic optima, but supporting data from wild populations are still scarce 13 , 14 , 15 . Here we present evidence for sexually antagonistic fitness variation in a natural population, using data from a long-term study of red deer ( Cervus elaphus ). We show that male red deer with relatively high fitness fathered, on average, daughters with relatively low fitness. This was due to a negative genetic correlation between estimates of fitness in males and females. In particular, we show that selection favours males that carry low breeding values for female fitness. Our results demonstrate that sexually antagonistic selection can lead to a trade-off between the optimal genotypes for males and females; this mechanism will have profound effects on the operation of selection and the maintenance of genetic variation in natural populations.

Key Points With a rich and well understood natural history and a long tradition of being used to address fundamental issues in development, neuroscience, behaviour, ecology and evolution, social insects are now emerging as important model systems for genetic and genomic analyses of complex traits, namely, the remarkably diverse and intricate systems of division of labour exhibited by the ants, bees, wasps and termites. Hereditary effects on division of labour are more pervasive than previously supposed. The genes that underlie hereditary effects on division of labour have yet to be identified. Hereditary effects on division of labour raise the spectre of conflict between those that are reproducing and those that are not, but it seems that mechanisms have evolved in many species to minimize conflict while still preserving genetic diversity and its potential benefits to colony life. Hereditary effects on one form of division of labour, that is, queen–worker caste determination, have another cost: decreased caste-ratio flexibility. Some findings suggest that environmental factors mitigate this genetic bias, but more research is needed. Hereditary effects on another form of division of labour, that is, worker–worker specialization, benefit colonies by increased efficiency of division of labour or increased colony homeostasis. Molecular analyses of candidate genes and gene expression profiling reveal that the same set of highly conserved molecular pathways (for example, insulin) are involved in the regulation of different forms of division of labour, even across distantly related social insect taxa that evolved eusociality independently. Some of these pathways are related to the fundamental processes of nutrition, metabolism and reproduction, supporting the idea that life-history traits of solitary insects that are related to these processes could have served as evolutionary precursors to eusociality. The sequencing of the first social insect genome, that of the honeybee, has led to several important findings, including the discovery that the molecular basis of queen–worker caste determination involves insulin signalling and epigenetic regulation. We predict that there will be whole genome sequences for 10–20 social insect species and their relatives within the next 10 years, and these could be strategically chosen to span the full range of sociality — from solitary to eusocial — to provide powerful resources to study the mechanisms and evolution of division of labour. Social insects have been so successful because individuals cooperate, bringing direct benefit to the community and indirect benefit to themselves. The genetic and molecular basis of this cooperativity, and of the conflict that often underlies it, is beginning to be uncovered. Division of labour — individuals specializing in different activities — features prominently in the spectacular success of the social insects. Until recently, genetic and genomic analyses of division of labour were limited to just a few species. However, research on an ever-increasing number of species has provided new insight, from which we highlight two results. First, heritable influences on division of labour are more pervasive than previously imagined. Second, different forms of division of labour, in lineages in which eusociality has arisen independently, have evolved through changes in the regulation of highly conserved molecular pathways associated with several basic life-history traits, including nutrition, metabolism and reproduction.