Frugal fat or munificent muscle: genomic imprinting and metabolism

Variation in body composition is a popular obsession. The culturally ‘ideal’ body type is light on fat and heavy on muscle but the human population is collectively laying on fat. A new study finds antagonistic effects of two imprinted genes, Grb10 and Dlk1, on body composition in mice. These findings pose the question whether there is an evolutionary conflict between genes of maternal and paternal origin over the optimal proportions of body fat and lean muscle mass. See research article: http://www.biomedcentral.com/1741-7007/12/9

Troubled sleep: Night waking, breastfeeding and parent–offspring conflict

Disrupted sleep is probably the most common complaint of parents with a new baby. Night waking increases in the second half of the first year of infant life and is more pronounced for breastfed infants. Sleep-related phenotypes of infants with Prader-Willi and Angelman syndromes suggest that imprinted genes of paternal origin promote greater wakefulness whereas imprinted genes of maternal origin favor more consolidated sleep. All these observations are consistent with a hypothesis that waking at night to suckle is an adaptation of infants to extend their mothers’ lactational amenorrhea, thus delaying the birth of a younger sib and enhancing infant survival

Interbirth intervals: Intrafamilial, intragenomic and intrasomatic conflict

Background and objectives: Interbirth intervals (IBIs) mediate a trade-off between child number and child survival. Life history theory predicts that the evolutionarily optimal IBI differs for different individuals whose fitness is affected by how closely a mother spaces her children. The objective of the article is to clarify these conflicts and explore their implications for public health. Methodology: Simple models of inclusive fitness and kin conflict address the evolution of human birth-spacing. Results:: Genes of infants generally favor longer intervals than genes of mothers, and infant genes of paternal origin generally favor longer IBIs than genes of maternal origin. Conclusions and implications: The colonization of maternal bodies by offspring cells (fetal microchimerism) raises the possibility that cells of older offspring could extend IBIs by interfering with the implantation of subsequent embryos

The Strategic Gene

Gene-selectionists define fundamental terms in non-standard ways. Genes are determinants of difference. Phenotypes are defined as a gene’s effects relative to some alternative whereas the environment is defined as all parts of the world that are shared by the alternatives being compared. Environments choose among phenotypes and thereby choose among genes. By this process, successful gene sequences become stores of information about what works in the environment. The strategic gene is defined as a set of gene tokens that combines ‘actor’ tokens responsible for an effect with ‘recipient’ tokens whose replication is thereby enhanced. This set of tokens can extend across the boundaries of individual organisms, or other levels of selection, as these are traditionally defined.Organismic and Evolutionary Biolog

Divergent Mating Systems and Parental Conflict as a Barrier to Hybridization in Flowering Plants

Parental conflicts can lead to antagonistic coevolution of the sexes and of parental genomes. Within a population, the resulting antagonistic effects should balance, but crosses between populations can reveal conflict. Parental conflict is less intense in self‐pollinating plants than in outcrossers because outcrossing plants are pollinated by multiple pollen donors unrelated to the seed parent, while a self‐pollinating plant is primarily pollinated by one individual (itself). Therefore, in crosses between plants with differing mating systems, outcrossing parents are expected to “overpower” selfing parents. We call this the weak inbreeder/strong outbreeder (WISO) hypothesis. Prezygotically, such overpowering can alter pollination success, and we argue that our hypothesis explains a common pattern of unilateral incompatibility, in which pollen from self‐incompatible populations fertilizes ovules of self‐compatible individuals but the reciprocal cross fails. A postzygotic manifestation of overpowering is aberrant seed development due to parent‐of‐origin effects such as genomic imprinting. We evaluate evidence for the WISO hypothesis by reviewing published accounts of crosses between plants of different mating systems. Many, but not all, of such reports support our hypothesis. Since parental conflicts can perturb fertilization and development, such conflicts may strengthen reproductive barriers between populations, contributing to speciation.Organismic and Evolutionary Biolog

On Limits to Seed Production

Organismic and Evolutionary Biolog

Sarah and Constant Broyer, Pharmacist and Physician, of Carlton

Constant Broyer (1833–1911) trained as a herbalist in Victoria during the 1850s and practised as a medical botanist in Carlton in the 1860s. He obtained medical degrees from the Eclectic Medical College of Cincinnati (1875) and Harvard University (1879). He is perhaps the first Australian to have studied at Harvard. He was twice found guilty of manslaughter by a coroner’s jury in 1874 and 1896. Both cases were much publicised but Broyer was not prosecuted on either charge. His wife, Sarah Broyer (1829–1877), ran the family pharmacy during her husband’s absence in America in the 1870s. She was the first woman to apply for registration as a pharmacist in Victoria in 1877 under the new Pharmacy Act and was represented in her negotiations before the Pharmacy Board by a young barrister, Alfred Deakin. This article traces the chronology and major events shaping the personal, professional and public lives of Constant and Sarah Broyer (and their extended family) from the mid-nineteenth century to the 1940s.Organismic and Evolutionary Biolog

The Epidemiology of Epigenetics

Organismic and Evolutionary Biolog

Kinship Asymmetries and the Divided Self

Imprinted genes are predicted to affect interactions among relatives. Therefore, variant alleles at imprinted loci are promising candidates for playing a causal role in disorders of social behavior. The effects of imprinted genes evolved in the context of patterns of asymmetric relatedness that existed within social groups of our ancestors.Organismic and Evolutionary Biolog