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1.
The genetics of sex determination remain mysterious in many organisms, including some that are otherwise well studied. Here we report the discovery and analysis of the mating-type locus of the model organism Dictyostelium discoideum. Three forms of a single genetic locus specify this species' three mating types: two versions of the locus are entirely different in sequence, and the third resembles a composite of the other two. Single, unrelated genes are sufficient to determine two of the mating types, whereas homologs of both these genes are required in the composite type. The key genes encode polypeptides that possess no recognizable similarity to established protein families. Sex determination in the social amoebae thus appears to use regulators that are unrelated to any others currently known. 相似文献
2.
A laboratory strain of Drosophila mercatorum has existed for 20 years without males and therefore without natural selection operating to maintain the genetic basis of female mating behavior. The females of this strain have recently experienced a genetic impairment of mating capacity. This observation exemplifies the mode of evolution of vestigial characters and supports Muller's theory that random mutation will tend to destroy the genetic basis of a character from which selection has been removed. 相似文献
3.
Sexual conflict is thought to be a potent force driving the evolution of sexually dimorphic traits. In the water strider Rheumatobates rileyi, we show that elaborated traits on male antennae function to grasp resistant females during premating struggles. Using RNA interference, we uncovered novel roles of the gene distal-less (dll) in generating these male-specific traits. Furthermore, graded reduction of the grasping traits resulted in a graded reduction of mating success in males, thus demonstrating both selection for elaboration of the traits and the role of dll in their evolution. By establishing developmental genetic tools in model systems where sexual selection and conflict are understood, we can begin to reveal how selection can exploit ancient developmental genes to enable the evolution of sexually dimorphic traits. 相似文献
4.
Transcriptional regulation in the yeast life cycle 总被引：35，自引：0，他引：35
5.
Michalczyk Ł Millard AL Martin OY Lumley AJ Emerson BC Chapman T Gage MJ 《Science (New York, N.Y.)》2011,333(6050):1739-1742
The widespread phenomenon of polyandry (mating by females with multiple males) is an evolutionary puzzle, because females can sustain costs from promiscuity, whereas full fertility can be provided by a single male. Using the red flour beetle, Tribolium castaneum, we identify major fitness benefits of polyandry to females under inbreeding, when the risks of fertilization by incompatible male haplotypes are especially high. Fifteen generations after inbred populations had passed through genetic bottlenecks, we recorded increased levels of female promiscuity compared with noninbred controls, most likely due to selection from prospective fitness gains through polyandry. These data illustrate how this common mating pattern can evolve if population genetic bottlenecks increase the risks of fitness depression due to fertilization by sperm carrying genetically incompatible haplotypes. 相似文献
6.
Bowles S 《Science (New York, N.Y.)》2006,314(5805):1569-1572
Humans behave altruistically in natural settings and experiments. A possible explanation-that groups with more altruists survive when groups compete-has long been judged untenable on empirical grounds for most species. But there have been no empirical tests of this explanation for humans. My empirical estimates show that genetic differences between early human groups are likely to have been great enough so that lethal intergroup competition could account for the evolution of altruism. Crucial to this process were distinctive human practices such as sharing food beyond the immediate family, monogamy, and other forms of reproductive leveling. These culturally transmitted practices presuppose advanced cognitive and linguistic capacities, possibly accounting for the distinctive forms of altruism found in our species. 相似文献
7.
Sexual selection is a potent evolutionary force. However, very few models have considered the evolution of female preferences for traits expressed in both sexes. Here we explore how female preferences coevolve with sexually antagonistic traits, which involve alleles that are beneficial to one sex but harmful to the other. We show that with a sexually antagonistic trait on the X chromosome (males XY, females XX), females evolve to prefer mates carrying alleles beneficial to daughters. In contrast, with a Z-linked trait (males ZZ, females ZW), females more often evolve mating preferences for mates carrying alleles beneficial to sons (that is, flashy displays). 相似文献
8.
吴常信 《中国农业大学学报》1981,(2):71-76
一个雄亲与数个雌亲相配所组成的家系是一个全同胞——半同胞混合的家系。雌亲内的后代是全同胞,雌亲间的后代是半同胞,这样一个家系内的亲缘相关随着配种的雌亲数和每个雌亲的后代数量的不同而变化。本文提出了计算这种混合家系亲缘相关的一个近似公式,并证明即使是对后代作随机抽样的情况下也是适用的。 相似文献
9.
Since its classification nearly 80 years ago, the human pathogen Candida albicans has been designated as an asexual yeast. In this report, we describe the construction of C. albicans strains that were subtly altered at the mating-type-like (MTL) locus, a cluster of genes that resembles the mating-type loci of other fungi. These derivatives were capable of mating after inoculation into a mammalian host. C. albicans is a diploid organism, but most of the mating products isolated from a mouse host were tetrasomic for the two chromosomes that could be rigorously monitored and, overall, exhibited substantially higher than 2n DNA content. These observations demonstrated that C. albicans can recombine sexually. 相似文献
10.
Genetic similarity owing to kin relationship is often invoked to explain the evolution of social cooperation. In this study, male color morphs of side-blotched lizards settle nonrandomly with respect to genetic similarity. Blue morphs tend to settle in close proximity to other blue morphs with high genetic similarity. Blue neighbors have three times the average fitness of blue males lacking such neighbors. Conversely, genetically similar males depress fitness of the orange morph. Moreover, orange males are hyperdispersed with respect to genetic similarity. Pedigree and dispersal data show that genetically similar blue neighbors are not kin. Instead, conditions for the evolution of dispersal and cooperation are promoted by an emergent property of the morph locus that increases genetic similarity within morphs: genome-wide correlational selection links many traits to the morph locus, including settlement behavior. 相似文献
11.
Analysis of isozyme variability demonstrates that bracken fern (Pteridium aquilinum) has a diploid genetic system and expresses solely disomic inheritance patterns. Electrophoretic data indicate that genetically variable progeny are produced in natural populations after intergametophytic mating rather than by a process involving recombination between duplicated unlinked loci. Although some enzymes are encoded by more than one locus, this has resulted from subcellular compartmentalization of isozymes, and there is no evidence of extensive gene duplication resulting from polyploidy. The conclusions reached in this report differ from those which propose polyploidy as an adaptive mechanism for maintaining genetic variability in Pteridium and other homosporous pteridophytes. 相似文献
12.
Cade WH 《Science (New York, N.Y.)》1981,212(4494):563-564
Male field crickets, Gryllus integer, call and attract mates, or they silently intercept females attracted to calling males. Selection experiments demonstrate that the duration of nightly calling has an important genetic component. Mean calling times in high and low lines were significantly different and had realized heritabilities of 0.50 and 0.53, respectively. Selection can operate in such a way that each of the alternative forms of male reproductive behavior is associated with a specific genetic substrate. This has not yet been shown for other species in which males adopt contrasting modes of mating behavior. 相似文献
13.
多次交配对昆虫适应性的影响 总被引：5，自引：0，他引：5
多次交配行为广泛存在于各种昆虫种类中.然而,目前对于昆虫多次交配行为的维持与进化的理解仍然存在疑惑.从物质利益和基因利益两方面综述昆虫多次交配发生的机制,并从亲代的产卵量、寿命、生殖力、子代的存活力与基因多样性等方面论述多次交配对昆虫适应性的影响. 相似文献
14.
Ecological genetics and natural selection in molluscs 总被引：3，自引：0，他引：3
J S Jones 《Science (New York, N.Y.)》1973,182(112):546-552
Polymorphic snails of the genus Cepaea have been widely used for research in ecological genetics. Natural selection by selective predation is important in controlling morph frequencies in some populations of C. nemoralis in England. The importance of environmental selection in affecting other patterns of local genetic differentiation of population structure (area effects) is a matter of controversy. Some authors emphasize divergent evolution of whole gene pools between area effects, while others feel that climatic selection acting on individual loci is important. Analysis of 500,000 C. nemoralis snails from throughout Europe shows that there is a strong positive association between gene frequencies at the shell color locus and mean summer temperature, but that no climatic correlations are obvious at other loci. Another species, C. vindobonensis, which has a much simpler system of polymorphism than does C. nemoralis, was investigated in Yugoslavia, in a region where there is known to be intense microclimatic differentiation because of the accumulation of cold air in frost hollows. There was a striking tendency for snails with lightly pigmented shell bands to be found in places with a warm microclimate. Physiological and behavioral experiments demonstrate that this is due primarily to differential energy absorption from sunshine by the different shell phenotypes. As in C. nemoralis, other C. vindobonensis phenotypes show no detectable association with the environment. It is possible that genes whose frequencies cannot be related to environmental selection may have evolved strong linkage interactions with other genes in the population's gene pool. Selection by the ecological environment and the genetic environment may therefore both be important in controlling the genetic structure of snail populations. 相似文献
15.
Theory on the evolution of ornamental male traits by sexual selection assumes consistency in selection over time. Temporal variation in female choice could dampen sexual selection, but scant information exists on the degree to which individual female preferences are flexible. Here we show that in lark buntings sexual selection on male traits varied dramatically across years and, in some cases, exhibited reversals in the direction of selection for a single trait. We show that these shifts are probably because of flexibility in mate choice by individual females and that they parallel shifts in the male traits that predict female reproductive success in a given year. Plasticity in choice and concomitant reversals in mating patterns across time may weaken the strength of sexual selection and could maintain genetic variation underlying multiple sexual ornaments. 相似文献
16.
The behavioral and ecological factors involved in immune system evolution remain poorly explored. We present a phylogenetic analysis of white blood cell counts in primates to test three hypotheses related to disease risk: increases in risk are expected with group size or population density, exposure to soil-borne pathogens, and mating promiscuity. White blood cell counts were significantly greater in species where females have more mating partners, indicating that the risk of sexually transmitted disease is likely to be a major factor leading to systematic differences in the primate immune system. 相似文献
17.
This gene pyramiding strategy is based on the idea of efficiently pyramiding genes of interest by crosses and selection to obtain a population with favorable alleles from different breeds or lines, which is called an ideal population. We investigate impacts of some factors on the pyramiding efficiencies by simulation. These factors include selection strategies (the breeding value selection, the molecular scores selection and the index selection), proportion selected (2, 10 and 20%), recombination rates between adjacent target genes (0.1, 0.3 and 0.5) and different mating types (the random mating and the positive assortative mating avoiding sib mating). The results show that: (1) The more recombination rate and the lower proportion male selected, the better pyramiding efficiency; (2) the ideal population is obtained via various selection strategies, while different selection strategies are suitable for different breeding objectives. From the perspective of pyramiding target genes merely, the molecular scores selection is the best one, for the purpose of pyramiding target genes and recovering genetic background of the target trait, the index selection is the best one, while from the saving cost point of view, the breeding value selection is the best one; (3) the positive assortative mating is more efficient for gene pyramiding compared with the random mating in the terms of the number of generations of intercross for getting the ideal population. 相似文献
18.
Candille SI Kaelin CB Cattanach BM Yu B Thompson DA Nix MA Kerns JA Schmutz SM Millhauser GL Barsh GS 《Science (New York, N.Y.)》2007,318(5855):1418-1423
Genetic analysis of mammalian color variation has provided fundamental insight into human biology and disease. In most vertebrates, two key genes, Agouti and Melanocortin 1 receptor (Mc1r), encode a ligand-receptor system that controls pigment type-switching, but in domestic dogs, a third gene is implicated, the K locus, whose genetic characteristics predict a previously unrecognized component of the melanocortin pathway. We identify the K locus as beta-defensin 103 (CBD103) and show that its protein product binds with high affinity to the Mc1r and has a simple and strong effect on pigment type-switching in domestic dogs and transgenic mice. These results expand the functional role of beta-defensins, a protein family previously implicated in innate immunity, and identify an additional class of ligands for signaling through melanocortin receptors. 相似文献
19.
Close relatedness has long been considered crucial to the evolution of eusociality. However, it has recently been suggested that close relatedness may be a consequence, rather than a cause, of eusociality. We tested this idea with a comparative analysis of female mating frequencies in 267 species of eusocial bees, wasps, and ants. We found that mating with a single male, which maximizes relatedness, is ancestral for all eight independent eusocial lineages that we investigated. Mating with multiple males is always derived. Furthermore, we found that high polyandry (>2 effective mates) occurs only in lineages whose workers have lost reproductive totipotency. These results provide the first evidence that monogamy was critical in the evolution of eusociality, strongly supporting the prediction of inclusive fitness theory. 相似文献
20.
小尾寒羊血液蛋白多态性与多羔性研究 总被引：7，自引：0，他引：7
通过非连续性垂直板聚丙烯酰胺凝胶电泳(PAGE)对小尾寒羊的8种血液蛋白(酶)进行多态性检测,同时以甘肃藏羊作为对照,探索绵羊多羔性与血液生化遗传的相关性。结果表明:Hb位点的HbB基因、Tf位点的TfC基因、Es的Es-基因与绵羊多羔性可能存在相关性,Ep是否可以作为小尾寒羊多羔性的遗传标记,还需进一步探讨,其它4个蛋白(酶)AIb、Pr、AMY、LDH与绵羊多羔性不相关;同时得出与多羔性相关的蛋白位点基因与目前所研究的多胎基因FecB等主效基因均不连锁,但存在相关性。 相似文献