Showing papers by "Laurence D. Hurst published in 1992"
TL;DR: It is argued that in systems with fusion of gametes, the mating type genes are typically binary and regulate cytoplasmic inheritance, and binary sexes have evolved several times independently associated with fusion, although at least twice binary types have been lost, associated with a loss of fusion.
Abstract: Binary mating types are proposed to arise in a three-stage process through selection of nuclear genes to minimize cytoplasmic gene conflict at the time of gamete fusion. In support of this view we argue that: (i) in systems with fusion of gametes, the mating type genes are typically binary and regulate cytoplasmic inheritance; (ii) binary sexes have evolved several times independently associated with fusion, although at least twice binary types have been lost, associated with a loss of fusion; further, in accordance with the theory are findings for isogamous species that (iii) close inbreeding may correlate with less than two sexes and biparental inheritance of cytoplasmic genes; and (iv) species with more than two sexes may have uniparental inheritance of cytoplasmic genes, be rare and be afflicted by deleterious cytoplasmic genes which attempt to pervert normal cytoplasmic genetics. Such facts and their rationale support a new and unified definition of sexes based on the control of the inheritance of cytoplasmic genes. For the common cases, the male sex is that which resigns attempts to contribute cytoplasmic genes to the next generation. We differentiate between sexes and the incompatibility types of ciliates, basidiomycetes, some angiosperms and a few other organisms which are independent of organelle contribution.
196 citations
TL;DR: It is argued that intragenomic conflict might be an important evolutionary force, and may influence the evolution of sex determining systems, sex allocation systems and post-zygotic isolating mechanisms.
Abstract: Ultra-selfish genes increase in frequency in a population despite the harm they inflict on their host. The spread of both ultra-selfish genes and their suppressors is evidence of conflicts between genes within an individual for transmission into the next generation. Here I synthesize a body of past work, and argue that intragenomic conflict might be an important evolutionary force. I discuss the evolutionary history of cytoplasmic genes as an illustration. I first consider the evolution of sex. Recent evidence suggests that the initial evolution of sex might have been driven by an ultra-selfish gene. The existence of sex in turn creates a series of new conflicts which may explain the existence of sexes and uniparental inheritance of cytoplasmic genes. Uniparental inheritance of cytoplasmic genes sets up a new set of conflicts over the sex ratio, which in turn may influence the evolution of sex determining systems, sex allocation systems and post-zygotic isolating mechanisms.
105 citations
TL;DR: It is proposed that Stellate was originally a meiotic drive gene, which was possibly not required for spermatogenesis, and which can render the host sterile unless suppressed ever have evolved.
Abstract: Is Stellate a Relict Meiotic Driver? X 0 males of Drosophila melanogaster are sterile. Associated with this sterility is the presence of crystals in the sperm. Crystal production is determined by the Stellate (Ste) locus which maps to position 45.7 on the X chromosome (HARDY et al. 1984). Expression of stellate is repressed in normal males by Suppressor of Stellate Su(Ste) on the Y chromosome just proximal to the fertility factor kl-2 (LIVAK 1984, 1990). In D. simulans and D. mauritiana the Stellate sequence has been identified on the Y chromosome whereas in D. erecta, D. teissieri and D. yakuba it is not found at all. This is taken as an indication that the gene is possibly not necessary for normal spermatogenesis (LIVAK 1990). How could a gene which is possibly not required for spermatogenesis, and which can render the host sterile unless suppressed ever have evolved? Below I attempt to answer this question by proposing that Stellate was originally a meiotic drive gene. Consider a Drosophilid with \" normal \" meiosis in the male. The meiotic process involves accurate packing and winding of DNA. Consider now a mutant gene on the X which interferes with DNA packing in such a manner that the Y chromosome is more profoundly affected than the X. This might be simply due to the fact that the large Y has more DNA or hetero-chromatin requiring packing than the X or because the Y has more sites of interaction with the mutant protein. In consequence the gene will be present in more than 50% of the viable sperm. So long as the fertility of this fly is not reduced too dramatically this gene can invade. In contrast, a comparable gene on the Y would not be successful. Formally the gene is a X vs. Y meiotic driver. Interference with the packing of heterochromatin is believed to underlie the mechanism of drive in the Segregation Distorter system in Drosophila (Wu 1991). As the driver invades so it imposes a cost in both reducing male fertility and biasing the sex ratio. Thus a suppressor of this condition on the Y chromosome can also invade and go to a stable equilibrium (HURST and POMIANKOWSKI 1991). If this suppressor acts in a dose dependent fashion then a duplication of the driver locus can once again act as a driver by evading suppression. This driver can in turn however be …
51 citations
34 citations
TL;DR: This work has suggested that a host of phenomena, from exquisite details of gene expression to the evolution of crossing over, may all be explicable as the result of conflict within the nuclear genome.
Abstract: The last 20 years have seen the accumulation of a large body of information on selfish genetic elements — genes that act to further their own evolutionary interests at a cost to the individual (genome) bearing them. During the last few years, a growing number of authors have suggested that the intragenomic conflict these elements create is not just an intriguing example of natural selection in action, but a driving force behind the evolution of genetic systems. A host of phenomena, from exquisite details of gene expression to the evolution of crossing over, from the existence of syncytia during gametogenesis to the amount of DNA present in eukaryotes and the existence of multicopy genes, may all be explicable as the result of conflict within the nuclear genome.
29 citations
12 citations