Meiotic drivers are genetic variants that selfishly manipulate the production of gametes to increase their own rate of transmission, often to the detriment of the rest of the genome and the individual that carries them. This genomic conflict potentially occurs whenever a diploid organism produces a haploid stage, and can have profound evolutionary impacts on gametogenesis, fertility, individual behaviour, mating system, population survival, and reproductive isolation. Multiple research teams are developing artificial drive systems for pest control, utilising the transmission advantage of drive to alter or exterminate target species. Here, we review current knowledge of how natural drive systems function, how drivers spread through natural populations, and the factors that limit their invasion. Trends Box  Both naturally occurring and synthetic "meiotic drivers" violate Mendel's law of equal segregation and can rapidly spread through populations even when they reduce the fitness of individuals carrying them. Synthetic drivers are being developed to spread desirable genes in natural populations of target species. How ecology influences the population dynamics of meiotic drivers is important for predicting the success of synthetic drive elements. An enduring puzzle concerns why some meiotic drivers persist at stable, intermediate frequencies rather than sweeping to fixation. Drivers can have a wide range of consequences from extinction to changes in mating system. preferentially associating with and moving toward the egg pole at Meiosis I) will be 75 transmitted to more than half of the maturing eggs. Although this bias does not necessarily 76 reduce the production of eggs (as only one egg matures per meiosis), the fitness of other 77 alleles at the same locus, that do not bias transmission, and alleles linked to them, is 78 reduced. Such meiotic drivers could reduce the fitness of individuals that carry them, if the 79 driving variant is genetically linked to deleterious mutations or has deleterious pleiotropic 80 effects. 81Male meiotic drive takes multiple forms -some at least partially meiotic, some entirely 82 post-meiotic -but all involve a driving element that prevents maturation or function of 83 sperm that do not contain it. Because haploid sperm within a single ejaculate compete to 84 fertilize the same pool of eggs, disabling non-carrier sperm results in transmission of the 85 driving element to more than half of the functional gametes and resulting offspring ([5], Box 86 1). However, disabling non-carrier sperm often reduces fertility [6]. 87Spore drive in fungi, in which the products of meiosis are packaged together in an ascus, 88 operates via similar mechanisms. Spores with one haploid genotype will kill or disable 89 spores of the alternative haplotype ([7], Box 1). If spores disperse long distances sibling 90 spores are unlikely to compete and killing them will not increase the killer's fitness. 91However, spore killing can be beneficial if there is local resource competition. 92Excit...

Anecdotal evidence suggests that socioeconomic shocks strongly affect wildlife populations, but quantitative evidence is sparse. The collapse of socialism in Russia in 1991 caused a major socioeconomic shock, including a sharp increase in poverty. We analyzed population trends of 8 large mammals in Russia from 1981 to 2010 (i.e., before and after the collapse). We hypothesized that the collapse would first cause population declines, primarily due to overexploitation, and then population increases due to adaptation of wildlife to new environments following the collapse. The long-term Database of the Russian Federal Agency of Game Mammal Monitoring, consisting of up to 50,000 transects that are monitored annually, provided an exceptional data set for investigating these population trends. Three species showed strong declines in population growth rates in the decade following the collapse, while grey wolf (Canis lupus) increased by more than 150%. After 2000 some trends reversed. For example, roe deer (Capreolus spp.) abundance in 2010 was the highest of any period in our study. Likely reasons for the population declines in the 1990s include poaching and the erosion of wildlife protection enforcement. The rapid increase of the grey wolf populations is likely due to the cessation of governmental population control. In general, the widespread declines in wildlife populations after the collapse of the Soviet Union highlight the magnitude of the effects that socioeconomic shocks can have on wildlife populations and the possible need for special conservation efforts during such times.

Parthenogenetic species of Caucasian rock lizards of the genus Darevksia are important evidence for reticulate evolution and speciation by hybridization in vertebrates. Female‐only lineages formed through interspecific hybridization have been discovered in many groups. Nevertheless, critical mechanisms of oogenesis and specifics of meiosis that provide long‐term stability of parthenogenetic species are still unknown. Here we report cytogenetic characteristics of somatic karyotypes and meiotic prophase I nuclei in the diploid parthenogenetic species Darevskia unisexualis from the new population “Keti” in Armenia which contains an odd number of chromosomes 2n = 37, instead of the usual 2n = 38. We revealed 36 acrocentric chromosomes and a single metacentric autosomal chromosome, resulting from Robertsonian translocation. Comparative genomic hybridization revealed that chromosome fusion occurred between two chromosomes inherited from the maternal species, similar to another parthenogenetic species D. rostombekowi. To trace the chromosome behaviour in meiosis, we performed an immunocytochemical study of primary oocytes' spread nuclei and studied chromosome synapsis during meiotic prophase I in D. unisexualis based on analysis of synaptonemal complexes (SCs). We found meiotic SC‐trivalent composed of one metacentric and two acrocentric chromosomes. We confirmed that the SC was assembled between homeologous chromosomes inherited from two parental species. Immunostaining of the pachytene and diplotene nuclei revealed a mismatch repair protein MLH1 loaded to all autosomal SC bivalents. Possible mechanisms of meiotic recombination between homeologous chromosomes are discussed.

The all-female Caucasian rock lizard species Darevskia dahli and other parthenogenetic species of this genus reproduce normally via true parthenogenesis. Previously, the genetic diversity of this species was analyzed using allozymes, mitochondrial DNA, and DNA fingerprint markers. In the present study, variation at three microsatellite loci was studied in 111 specimens of D. dahli from five populations from Armenia, and new information regarding clonal diversity and clone formation in D. dahli was obtained that suggests a multiple hybridization origin. All individuals but one were heterozygous at the loci studied. Based on specific allele combinations, 11 genotypes were identified among the individuals studied. Individuals with the same genotypes formed distinct clonal lineages: one major clone was represented by 72 individuals, an intermediate clone was represented by 21 individuals, and nine other clones were rare and represented by one or several individuals. A new approach based on the detection and comparison of genotype-specific markers formed by combinations of parental-specific markers was developed and used to identify at least three hybridization founder events that resulted in the initial formation of one major and two rare clones. All other clones, including the intermediate and seven rare clones, probably arose through postformation microsatellite mutations of the major clone. This approach can be used to identify hybridization founder events and to study clone formation in other unisexual taxa.

No abstract