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At least 433 records · Page 24Linked to original sources
PubMed2006

Mating factor linkage and genome evolution in basidiomycetous pathogens of cereals.

Sex in basidiomycete fungi is controlled by tetrapolar mating systems in which two unlinked gene complexes determine up to thousands of mating specificities, or by bipolar systems in which a single locus (MAT) specifies different sexes. The genus Ustilago contains bipolar (Ustilago hordei) and tetrapolar (Ustilago maydis) species and sexual development is associated with infection of cereal hosts. The U. hordei MAT-1 locus is unusually large (approximately 500 kb) and recombination is suppressed in this region. We mapped the genome of U. hordei and sequenced the MAT-1 region to allow a comparison with mating-type regions in U. maydis. Additionally the rDNA cluster in the U. hordei genome was identified and characterized. At MAT-1, we found 47 genes along with a striking accumulation of retrotransposons and repetitive DNA; the latter features were notably absent from the corresponding U. maydis regions. The tetrapolar mating system may be ancestral and differences in pathogenic life style and potential for inbreeding may have contributed to genome evolution.

Edible Grain↗
PubMed2003

Male fitness of honeybee colonies (Apis mellifera L.).

Honeybees (Apis mellifera L.) have an extreme polyandrous mating system. Worker offspring of 19 naturally mated queens was genotyped with DNA microsatellites, to estimate male reproductive success of 16 drone producing colonies. This allowed for estimating the male mating success on both the colony level and the level of individual drones. The experiment was conducted in a closed population on an isolated island to exclude interferences of drones from unknown colonies. Although all colonies had produced similar numbers of drones, differences among the colonies in male mating success exceeded one order of magnitude. These differences were enhanced by the siring success of individual drones within the offspring of mated queens. The siring success of individual drones was correlated with the mating frequency at the colony level. Thus more successful colonies not only produced drones with a higher chance of mating, but also with a significantly higher proportion of offspring sired than drones from less successful colonies. Although the life cycle of honeybee colonies is very female centred, the male reproductive success appears to be a major driver of natural selection in honeybees.

Animals↗
PubMed2001

Male mating preference for female survivorship in the seaweed fly Gluma musgravei (Diptera: Coelopidae).

The seaweed fly mating system is characterized by pre-mating struggles during which females exhibit a mate rejection response involving kicking, shaking and abdominal curling. Males must resist rejection until females become passive and allow copulation to take place. However, despite the vigorous nature of the struggle males frequently dismount passive females without attempting copulation. Here we show that rejected females suffered higher post-encounter mortality rates than those accepted by males in the seaweed fly Gluma musgravei. Furthermore, we show that males also preferentially mounted females with higher future longevity. We propose that this male mate choice for female survivorship has evolved as a result of females often having to survive for long periods after mating until suitable oviposition sites become available. Such male preferences for female survivorship may be common in species in which oviposition must sometimes be substantially delayed after mating.

Animals↗
PubMedDate not supplied

Reproductive biology of the slender loris (Loris lydekkerianus lydekkerianus).

The slender loris (Loris lydekkerianus lydekkerianus), a nocturnal prosimian, was studied for 21 months in its natural habitat of scrub jungle in Dindigul, south India. Here we report on its reproductive biology. Identified and unidentified lorises were observed for a total of 2,656 h. Reproductive seasonality was seen, with births and oestrus observed to be highest in April-June and October-December. The mating system was promiscuous with 1 female mating successively with 3-4 males. A gestation period of 5.5 months and an inter-birth interval of 7 months were recorded. Adult females had a reproductive potential of 4 infants per year. The findings presented in this paper constitute the first information on the life history parameters of wild slender lorises.

Animals↗
PubMed1988

Comparison of pedigreed and nonpedigreed randombred control systems for use with artificial selection in the Japanese quail.

The performance characteristics of six replicate sublines of a randombred control, three pedigreed (P) and three nonpedigreed (NP), were studied to see if the NP mating system could be used as a method for maintaining a randombred control for selection experiments. Each subline was maintained with 32 single-pair matings, with 64 offspring placed each generation for each line. Brother X sister matings were avoided in the P but not in the NP system. The NP chicks were pedigreed in order to determine the exact numbers of brother X sister matings selected in that system, but pedigrees were not considered during selection. Records were collected on the numbers of matings producing offspring, the expected rate of inbreeding based on the effective population size, hatchability, egg production, egg weight, and the body weights of the males and females. Replicate lines in the P system had more matings that produced viable offspring, which resulted in larger effective population sizes, lower rates of inbreeding, and smaller average family sizes than those in the NP system. A number of significant differences were found between means of the replicate lines within system and between regressions of the traits measured in the individual lines on generation number. Most of these differences disappeared when the data from the three replicates within mating system were pooled and compared, suggesting that differences found between lines within system were due to random genetic drift due to restrictions in population size. It is suggested that the NP system can be used as an effective control procedure for Japanese quail breeding experiments, but that more than 32 mating pairs should be used for its maintenance in order to reduce the amount of genetic drift within the control population.

Animals↗
PubMed2001

Development of an optimized interaction-mating protocol for large-scale yeast two-hybrid analyses.

BACKGROUND: Protein-protein interactions have decisive roles in almost all aspects of the structural and functional organization of cells. But in spite of the increasing amount of complete genome sequence data, the ability to predict protein function from sequences alone is limited. Therefore comprehensive analysis of protein-protein interactions, as derived from the yeast two-hybrid mating system, will yield valuable information for functional biology on a proteomic scale. RESULTS: We have developed an optimized interaction mating protocol for the yeast two-hybrid system, which gives increased mating efficiencies. This significantly reduces the effort and cost of cDNA library screening and allows multiple parallel approaches. Improved preincubation conditions before mating, and optimal cell densities and cell ratios enable almost quantitative mating of the yeast cells carrying the cDNA library. We have proved the applicability of this technology using 20 bait proteins to screen an Arabidopsis thaliana cDNA library, in spite of bait-dependent variations in mating efficiency. CONCLUSIONS: The improved yeast two-hybrid interaction-mating protocol presented here allows the multiple parallel screening of cDNA libraries. It can be carried out without specialized equipment and has the potential to be standardized and automated.

Arabidopsis↗
PubMed2002

Sexual selection on multivariate phenotype in wild and mass-reared Ceratitis capitata (Diptera: Tephritidae).

Males with a larger thorax and narrower face were found to be favoured by directional sexual selection in a previous field cage experiment where Ceratitis capitata males from the Seib 6-96 genetic sexing strain competed with wild males from Alto Valle (Patagonia) for the possession of wild females. Targets of sexual selection, however, might differ between wild and laboratory females as a response to adaptation to mass-rearing conditions. To evaluate possible divergences on the targets of sexual selection as a by-product of adaptation to mass-rearing conditions, field cage tests were performed with both wild and laboratory females. To avoid possible bias due to correlation among the measured traits (eye length [EL], face width [FW], head width [HW], and thorax length [TL]), a multivariate analysis was applied. Consistent with the previous experiment, the results indicated that TL and FW are probable targets of directional sexual selection independently of female strain. However, laboratory females were less selective than wild ones. Additionally, correlational sexual selection was detected acting on the multivariate phenotype. The effects of correlational selection overlap with those of directional selection on each single trait. The analysis of mating pair characteristics showed patterns that do not match the expectations for a random mating system. The current analysis indicates that during mating pair formation two processes overlap. On the one hand, sexual selection favours males with larger size (TL) and narrower faces (FW). This effect occurs in both wild and laboratory females. In addition, assortative mating based on both phenotype and origin was also observed.

Animals↗
PubMed2003

Overt and covert competition in a promiscuous mammal: the importance of weaponry and testes size to male reproductive success.

Male contests for access to receptive females are thought to have selected for the larger male body size and conspicuous weaponry frequently observed in mammalian species. However, when females copulate with multiple males within an oestrus, male reproductive success is a function of both pre- and postcopulatory strategies. The relative importance of these overt and covert forms of sexual competition has rarely been assessed in wild populations. The Soay sheep mating system is characterized by male contests for mating opportunities and high female promiscuity. We find that greater horn length, body size and good condition each independently influence a male's ability to monopolize receptive females. For males with large horns at least, this behavioural success translates into greater siring success. Consistent with sperm-competition theory, we also find that larger testes are independently associated with both higher copulation rates and increased siring success. This advantage of larger testes emerges, and strengthens, as the number of oestrous females increases, as dominant males can no longer control access to them all. Our results thus provide direct quantitative evidence that male reproductive success in wild populations of mammals is dependent upon the relative magnitude of both overt contest competition and covert sperm competition.

Animals↗
PubMed1980

Reproductive behaviour of wild chimpanzees in the Gombe National Park, Tanzania.

(1) The reproductive behaviour of chimpanzees in the Gombe National Park, Tanzania, was studied for 16 months and additional information came from 19 years of demographic data collected by Dr Jane Goodall and members of the Gombe Stream Research Centre. (2) The mating system of the Gombe chimpanzees comprises 3 mating patterns: (a) opportunistic, non-competitive mating, when an oestrous female may be mated by all the males in the group; (b) possessiveness, when a male forms a special short-term relationship with an oestrous female and may prevent lower ranking males from copulating with her; and (c) consortships, when a male and a female leave the group and remain alone, actively avoiding other chimpanzees. While males took the initiative in possessive behaviour and consortships, females had to co-operate for a successful relationship to develop. (3) Data from 14 conceptions indicated that the majority of females (9) became pregnant while participating in the restrictive mating patterns, possessiveness and consorting. Adult males showed differential frequencies of involvement in the restrictive mating patterns. The following male characteristics showed significant, positive correlations with participation in the restrictive patterns: (a) the amount of time spent in the same group as oestrous females, (b) the proportion of that time spent grooming oestrous females, and (c) the frequency with which males shared food with females. Dominance ranks of the adult males showed no consistent correlation with involvement in the restrictive patterns, but it was clear that the most dominant male did gain an advantage. He was the only male able to monopolize oestrous females by showing possessiveness. (4) Developmental and demographic data from observations for 19 years show that female chimpanzees have a very limited reproductive potential. Females reached menarche at about 11 years of age but this was followed by a period of adolescent sterility of median length 26 months. Each birth, if the infant survived, was followed by a long period of lactational amenorrhoea of median duration 42 months. The mean inter-birth interval of the Gombe chimpanzees was 5 years 8 months. Thus, the theoretical lifetime reproductive potential of females is 5-6 offspring who survive to weaning. Data on achieved reproductive success showed that females had a median of 3 births in their lifetime, with only 2 offspring surviving to reproductive age.

Animals↗
PubMed2006

The breeding system of wild red ruffed lemurs (Varecia rubra): a preliminary report.

Captive studies have shown that ruffed lemurs (Varecia) have an unusual suite of reproductive traits combined with extremely high maternal reproductive costs. These traits include the bearing of litters, nesting of altricial young, and absentee parenting. To characterize the breeding system of this enigmatic lemur, reproductive traits must be contextualized in the wild. Here, I provide a preliminary report of mating and infant care in one community of wild red ruffed lemurs (Varecia rubra). Observations span a 15-month period covering two birth seasons and one mating season on the Masoala Peninsula, Madagascar. Factors that are not possible to replicate in captivity are reported, such as mating pattern, natality and mortality rates, the location of nests within the home range, and the structuring of infant care within a natural community. V. rubra at Andranobe have a fission-fusion, multifemale-multimale grouping pattern and a polygamous mating system. They do not mate monogamously or live strictly in family-based groups as suggested by previous workers. During the first 2 months of life, nests and infant stashing localities are situated within each mother's respective core area, and inhabitants of each core area within the communal home range provide care for young. As part of their absentee parenting system, infants are left in concealed, protected, and supportive spots high in the canopy, while mothers travel distantly. This practice is termed 'infant stashing'. Alloparenting appears to be an integral part of V. rubra's overall reproductive strategy in the wild, as it was performed by all age-sex classes. Among the alloparental behaviors observed were infant guarding, co-stashing, infant transport, and allonursing. Alloparenting and absentee parenting may mitigate high maternal reproductive costs. Furthermore, V. rubra may have a breeding system in which genetic partners (i.e., mating partners) do not always correspond to infant care-providers. Combined with recently available information on the behavioral ecology of wild ruffed lemurs, this preliminary report suggests directions for in-depth studies on Varecia's breeding system.

Animals↗
PubMed1991

On the robustness of regular systems of inbreeding.

Half-sib, first cousin, half nth cousin, and nth cousin mating systems are robust in that small deviations from the mating structure will not significantly alter the levels of genetic identity or effect qualitative distinctions between the models. Substitution of nearest kin in matings may either increase or decrease the level of homozygosity depending on the mating structure; the effect of a single error in the mating structure is not an accurate indicator of the equilibrium resulting from recurrent errors. Models of mixed half nth cousin or nth cousin mating show that the relative frequency of the lowest order inbred mating essentially determines the level of homozygosity. Any positive relative frequency of more distant matings will reduce the probability of identity by descent under half-sib or first cousin mating to less than 1.

Alleles↗
PubMed1999

Dispersal and Inbreeding Avoidance.

Using a game-theoretical approach, we investigate the dispersal patterns expected if inbreeding avoidance were the only reason for dispersal. The evolutionary outcome is always complete philopatry by one sex. The rate of dispersal by the other sex depends on patch size and mating system, as well as inbreeding and dispersal costs. If such costs are sex independent, then two stable equilibria coexist (male or female philopatry), with symmetric domains of attraction. Which sex disperses is determined entirely by history, genetic drift, and gene flow. An asymmetry in costs makes one domain of attraction extend at the expense of the other. In such a case, the dispersing sex might also be, paradoxically, the one that incurs the higher dispersal costs. As asymmetry increases, one equilibrium eventually disappears, which may result in a sudden evolutionary shift in the identity of the dispersing sex. Our results underline the necessity to control for phylogenetic relationships (e.g., through the use of independent-comparisons methods) when investigating empirical trends in dispersal. Our model also makes quantitative predictions on the rate of dispersal by the dispersing sex and suggests that inbreeding avoidance may only rarely be the sole reason for dispersal.

evolutionarily stable strategy↗
PubMed2006

[Dynamics of allozyme heterozygosity in Siberian dwarf pine Pinus pumila (Pall.) Regel populations of the Russian Far East: comparison of embryos and maternal plants].

Siberian dwarf pine, or Japanese stone pine, Pinus pumila (Pall.) Regel is widespread in eastern Siberia and the Russian Far East; the species is bird-dispersed and has a unique spreading or shrub living form. A mixed mating system (predominant outcrossing with self-pollination and matings of close relatives) leads to the formation of partly inbred progenies in P. pumila, as in the majority of other conifers. The question arises as to whether inbred individuals persist in the reproductive part of a population, which can have negative genetic consequences. The ADH, FDH, FEST, GDH, GOT, IDH, LAP, MNR, MDH, PEPCA, 6-PGD, PGI, PGM, SKDH, and SOD isozyme systems were analyzed to study the dynamics of heterozygosity in four P. pumila natural populations from the Pacific region, optimal for the species. Samples were collected in northern Koryakia, southern Kamchatka (two samples), and the Kunashir Island (Kurils). Wright's fixation index was used to estimate the level of inbreeding in embryos from dormant seeds resulting from free pollination and in maternal plants. A substantial level of inbreeding (F(IS) = 0.124-0.342) was observed in the embryo samples but not in three out of the four adult samples. The inbreeding level at the reproductive age was high only in the sample from Koryakia, which was explained by a relatively young age of plants in the population frequently affected by fires. A general increase in heterozygosity, characteristic of other conifers as well, was attributed to elimination of inbred progenies and by balancing selection for heterozygotes, which is a key factor maintaining allozyme polymorphism in populations.

Breeding↗