Search Results

The CCR5-Δ‎32 allele provides some of the most fascinating stories of the CCR5 gene. It became a focal point in the debate about allele frequencies and natural selection. Could those who are immune to AIDS have ancestors who were immune to the bubonic plague, smallpox, or Staphylococcus infection? How can historians collaborate with population geneticists and demographers to provide a richer history of medicine and biology and a clearer picture of the forces of natural selection? A history of CCR5-Δ‎32 is informative because it typifies how molecular biologists, population geneticists, biomedical researchers, and evolutionary biologists study alleles and mutations and determine which ones are present in various human populations. They key question is: should those populations be understood as races?

Genetics is the study of the inheritance of differences among individuals. Genomic approaches now make it possible to better understand the genetic basis and adaptive significance of phenotypic differences among individuals. Population-level differences in disease resistance will have important implications for population persistence in the face of emergent infectious diseases. In addition, understanding the genomic basis for that phenotype will be crucial for conservation efforts such as genetically informed breeding for reintroductions, genetic rescue of infected populations, and population restoration following declines. Most phenotypic differences between individuals within populations have both genetic and environmental causes. Raising individuals from different populations in the same environmental conditions can be used to test if there is a genetic component to phenotypic differences among populations. Understanding and maintaining phenotypic differences between individuals within populations and between populations can play a crucial role in conservation.

Despite many inequalities in the world, it is a testament to human technology that modern agriculture is able to feed the 8 billion people on the planet. However, recently extreme weather patterns linked to global warming have been having an adverse effect on crops and farmed animal production, leading to fears about whether agriculture can continue to feed all the humans on the planet. Genome editing looks set to revolutionise agriculture by making it possible to precisely edit the genomes of farm plants and animals rapidly and economically in an unprecedented way. Such editing could be used to create vegetables and meat with enhanced flavour or nutrition. It could also be used to create disease resistant plants and animals, and reduce the use of antibiotics or pesticides. Looking further into the future it might eventually be possible to use genome editing to reconfigure plants or animals to survive in increasingly extreme types of climates. Despite these positive ways of using genome editing in agriculture, concerns have been raised about the safety of food produced from genome edited animals and plants, and potential adverse effects on animal welfare. Another criticism is that genome editing may only benefit giant agribusiness companies, and not ordinary farmers and consumers. Yet against this criticism, one of the revolutionary aspects of genome editing is how easy and economical it is to use, which means that unlike previous GM technologies, there is no reason why it cannot be used in a local, sustainable, and accessible way.

Behaviours are the responses by organisms to environmental problems, whether these involve movement or not. These problems can be generalized and are uniform for most organisms; finding food, avoiding pests and predators, and locating mates. Behaviour and intelligence in all organisms underpins fitness, and that includes plants, too. Plants, however, explore and exploit their two environments, above and below ground, by growth rather than movement. A simple model, developed by Herbert Simon, is used to describe plant behaviour. The model indicates that plants do not grow randomly—their behaviour is rational. Most higher plants have clear needs in terms of acquiring light energy, minerals, and water, and their phenotype changes, to access patchily distributed resources. Further needs require resistance to both predators and disease. Behavioural responses to both are well established. Signalling mechanisms are basic to solving plant problems. Agnes Arber was a classical morphologist. Her description of behaviour is outlined, as are her research contributions, but the limitations of traditional morphology are indicated. The fundamental difference between plant and animal cells quoted by Arber lies in the necessary presence of the relatively rigid cell wall in plants. Nearly all the unique patterns of plant development and behaviour devolve from that one evolutionary acquisition, probably necessitated by sugar accumulation from photosynthesis. The notion that plants are merely populations of meristems is discussed and its limitations indicated. Visible plant behaviour, i.e. largely phenotypic plasticity, arises from the capability of self-organization that underpins plant development.