So far in this course we have dealt entirely with the evolution of characters that are controlled by simple Mendelian inheritance at a single locus. There are notes on the course website about gametic disequilibrium and how allele frequencies change at two loci simultaneously, but we didn’t discuss them. In every example we’ve considered we’ve imagined that we could understand something about evolution by examining the evolution of a single gene. That’s the domain of classical population genetics. For the next few weeks we’re going to be exploring a field that’s actually older than classical population genetics, although the approach we’ll be taking to it involves the use of population genetic machinery. If you know a little about the history of evolutionary biology, you may know that after the rediscovery of Mendel’s work in 1900 there was a heated debate between the “biometricians” (e.g., Galton and Pearson) and the “Mendelians” (e.g., de Vries, Correns, Bateson, and Morgan). Biometricians asserted that the really important variation in evolution didn’t follow Mendelian rules. Height, weight, skin color, and similar traits seemed to

Human biochemical genetics

▪ Abstract Insecticide resistance is an increasing problem in many insect vectors of disease Our knowledge of the basic mechanisms underlying resistance to commonly used insecticides is well established Molecular techniques have recently allowed us to start and dissect most of these mechanisms at the DNA level The next major challenge will be to use this molecular understanding of resistance to develop novel strategies with which we can truly manage resistance State-of-the-art information on resistance in insect vectors of disease is reviewed in this context

Insecticide Resistance in Insect Vectors of Human Disease

Gene drives may be capable of addressing ecological problems by altering entire populations of wild organisms, but their use has remained largely theoretical due to technical constraints. Here we consider the potential for RNA-guided gene drives based on the CRISPR nuclease Cas9 to serve as a general method for spreading altered traits through wild populations over many generations. We detail likely capabilities, discuss limitations, and provide novel precautionary strategies to control the spread of gene drives and reverse genomic changes. The ability to edit populations of sexual species would offer substantial benefits to humanity and the environment. For example, RNA-guided gene drives could potentially prevent the spread of disease, support agriculture by reversing pesticide and herbicide resistance in insects and weeds, and control damaging invasive species. However, the possibility of unwanted ecological effects and near-certainty of spread across political borders demand careful assessment of each potential application. We call for thoughtful, inclusive, and well-informed public discussions to explore the responsible use of this currently theoretical technology.

/pdf/concerning-rna-guided-gene-drives-for-the-alteration-of-wild-2la0voj6g0.pdf

Concerning RNA-guided gene drives for the alteration of wild populations

Site-specific selfish genes exploit host functions to copy themselves into a defined target DNA sequence, and include homing endonuclease genes, group II introns and some LINE-like transposable elements. If such genes can be engineered to target new host sequences, then they can be used to manipulate natural populations, even if the number of individuals released is a small fraction of the entire population. For example, a genetic load sufficient to eradicate a population can be imposed in fewer than 20 generations, if the target is an essential host gene, the knockout is recessive and the selfish gene has an appropriate promoter. There will be selection for resistance, but several strategies are available for reducing the likelihood of it evolving. These genes may also be used to genetically engineer natural populations, by means of population-wide gene knockouts, gene replacements and genetic transformations. By targeting sex-linked loci just prior to meiosis one may skew the population sex ratio, and by changing the promoter one may limit the spread of the gene to neighbouring populations. The proposed constructs are evolutionarily stable in the face of the mutations most likely to arise during their spread, and strategies are also available for reversing the manipulations.

/pdf/site-specific-selfish-genes-as-tools-for-the-control-and-56p3qs3uma.pdf

Site-specific selfish genes as tools for the control and genetic engineering of natural populations

genetics of the evolutionary process erpd genetics of the evolutionary process satcar 8 genetics from an evolutionary process perspective james genetics of the evolutionary process moersphila evolutionary genetics university of tennessee genetics of the evolutionary process junboku stochastic processes in evolutionary and disease genetics behavior genetics and evolutionary psychology genomics of the evolutionary process cell evolutionary genetics: progress and challenges bizzo and el-hani review darwin and mendel: evolution and pdf download genetics of the evolutionary process quantitative genetics approaches to study evolutionary genetics and the origin of species: an introduction and two evolutionary genetics memorial university genetics of the evolutionary process eaal genetics of the evolutionary process jlip evolution in mendelian populations genetics the genetic basis of evolutionary change vertebrate ageing: an evolutionary process with a genetic evolutionary genetics library of congress evolutionary genetics: from molecules to morphology the ecological genetics of speciation integrative biology biol2007 mendelian genetics and evolution 1) a parametric interpretation of bayesian nonparametric [page] genetics and evolutionary psychology the evolutionary process a critical study of evolutionary conservation genetics as applied evolution: from genetic introduction to molecular population genetics holsinger lab evolutionary genetics of california islands peromyscus population and evolutionary genetics mdmtv some mathematical models in evolutionary genetics the evolutionary genetics of personalityy lars penke origin and evolutionary process of the cns elucidated by genetic approaches in comparative and evolutionary physiology the evolutionary genetics of speciation genetics and evolution link.springer evolutionary genetics of digital library evolutionary genetics: part 1 polymorphism in dna causal foundations of evolutionary genetics philsci-archive biol334 – evolutionary genetics university of canterbury exercise 2: evolutionary population genetics by the genetics society perspectives the proper role of population genetics in modern notes on evolution and population genetics evolutionary and genetic aspects of biodiversity eolss chapter 1 genetics: an introduction correlation of ontogenetic and evolutionary processes in biol334 evolutionary genetics university of canterbury

Genetics of the Evolutionary Process

A Giemsa C-banding technique applied to the mosquito, Aedes aegypti, has revealed a distinctive banding pattern which is described as a reliable means of distinguishing between the morphologically similar X and Y chromosomes during all stages of mitosis and meiosis. The essential difference is that the Y chromosome, unlike the X and the autosomes, is not C-banded in the centromere region. An intercalary band is also present in one arm of all X chromosomes and some Y chromosomes. The distribution of these cytological markers throughout meiosis indicates that the sex locus occurs somewhere within a pericentric region, the minimum extent of which includes both the intercalary band and the centromere.

X and Y chromosomes of Aedes aegypti (L.) distinguished by Giemsa C-banding.

Meiotic drive in Aedes aegypti (L.) is shown by a Giemsa C-banding technique to be associated with preferential isochromatid breakage of the X chromosome during male meiosis. These breaks remain open at least until anaphase-I and, since the range of cells affected is proportional to the sensitivity of the X chromosome to the Distorter gene, it is argued that they are directly related to the decreased number of spermatozoa found in distorting males. This reduction is considered to be attributable to the degeneration of more X- than Y-bearing spermatids but it is probable that some non-functional X-bearing spermatozoa are also produced. Chromosome breakage is almost completely confined to four sites, two adjacent to the centromere, one just proximal to the intercalary band and another about the centre of the unbanded arm. Although the first three of these lie within a region in which crossing-over does not take place, fragmentation occurs more frequently in a chiasmate arm than in one devoid of chromatid exchange.

A cytogenetic analysis of meiotic drive in the mosquito, Aedes aegypti (L.)

The separate identities of the male-determining factor, M, and the sex-linked Distorter gene, D, are established in an Accra strain of Aedes aegypti. Their to each other and to Giemsa C-bands. Thus, M is invariably inherited with the centromere, whereas D lies towards the intercalary band. Approximately 1.2% recombination occurs between M and D but, in a chromosome known for its distal localization of chiasmata, it is argued that he two are not necessarily as closely linked cytologically as this might imply. Evidence on the genetic effects of recombination in the region of M and D is also considered.

Cytological mapping of the M and D loci in the mosquito, Aedes aegypti (L.)

A study has been made on the genetic basis of meiotic drive at the Distorter (D) locus which, in coupling with the male-determining gene (or region) M on the Y chromosome, causes production of excess male progeny. Its effect is regulated by the sensitivity/resistance of the X chromosome. This study demonstrates that there are two major loci controlling resistance/sensitivity to MD: (1) the m gene (or region) on the X chromosome (allelic with M) which may be either m

 R
 or m

 S
 (resistant or sensitive), (2) the t (tolerance) gene (or genes) which recombines with m and, if present, largely counteracts the effect of m

 S
 . There is also evidence that MD itself is capable of limited adaptation. The conclusions were derived from using MD males of the T30 or ACCRA strains (from Trinidad and Ghana respectively). The work involved the use of the CHIPEI and RED strains with sensitive X chromosomes, the latter also carrying the t (tolerance) gene which is linked to re (red eye) and m (the sex-determining locus or region) but recombines with both. The implications of these findings for using MD as a method of population control are discussed.

The genetic basis of resistance and sensitivity to the meiotic drive gene D in the mosquito Aedes aegypti L.

A genetic analysis of resistance to knockdown by permethrin and bioresmethrin in adults of the homozygous resistant strain of Aedes aegypti, BKPM3, was made. A major resistance gene R
pywas located approximately 13 cross-over units from the linkage group III marker, blt (black tarsus).

R. J. Wood

Papers

X and Y chromosomes of Aedes aegypti (L.) distinguished by Giemsa C-banding.

A cytogenetic analysis of meiotic drive in the mosquito, Aedes aegypti (L.)

Cytological mapping of the M and D loci in the mosquito, Aedes aegypti (L.)

The genetic basis of resistance and sensitivity to the meiotic drive gene D in the mosquito Aedes aegypti L.

Location of a gene conferring resistance to knockdown by permethrin and bioresmethrin in adults of the BKPM3 strain of Aedes aegypti