Effects Of Mating Research Articles

Implication of mating on oocyte development in red cotton bug, Dysdercus koenigii (Fabricius, 1775) (Heteroptera: Pyrrhocoridae)

Abstract The ovaries of Dysdercus koenigii are consisted of meroistic telotrophic ovarioles. Each ovariole can be differentiated into tropharium and vitellarium. The tropharium contains stem line oogonia, newly formed oocytes, trophocytes, prefollicular cells and follicular cells. The vitellarium possesses 10-12 developing oocytes. The developing oocytes are connected to the trophocytes, present in the tropharium, by nutritive cords. During premating period, the ovarioles change, resulting in increase the number of oocytes in the vitellarium. The developing oocytes in the initial stage of development are surrounded by columnar follicular cells, which are subsequently changed to cuboidal and squamous cells in a sequence. The process of vitellogenesis was initiated after 48 h of adult development with the appearance of perioocytic space. There was deposition of yolk material at the periphery of oocytes in the ovarioles of 72 h old females. The further development of oocytes and vitellogenesis remained suspended up to 12-14 days in the virgin females. On the other hand, mating stimulates the oocyte development and process of vitellogenesis. There were distinct morphometric and histological changes in the ovarioles as a consequence of mating; dimensions of vitellarium and oocytes of the mated female increased drastically. However, the size of tropharium and number of oocytes present in the vitellarium largely remained unchanged. The process of vitellogenesis also resumed followed by mating stimulus. Therefore, the oocytes were laden with yolk material; at this stage, the surrounded follicular layer is replaced by chorion.

Male age and its association with reproductive traits in captive and wild house sparrows

Evolutionary theory predicts that females seek extra‐pair fertilizations from high‐quality males. In socially monogamous bird species, it is often old males that are most successful in extra‐pair fertilizations. Adaptive models of female extra‐pair mate choice suggest that old males may produce offspring of higher genetic quality than young males because they have proven their survivability. However, old males are also more likely to show signs of reproductive senescence, such as reduced sperm quality. To better understand why old males account for a disproportionally large number of extra‐pair offspring and what the consequences of mating with old males are, we compared several sperm traits of both captive and wild house sparrows, Passer domesticus. Sperm morphological traits and cloacal protuberance volume (a proxy for sperm load) of old and young males did not differ substantially. However, old males delivered almost three times more sperm to the female's egg than young males. We discuss the possibility of a post‐copulatory advantage for old over young males and the consequences for females mated with old males.

A new defense in the battle of the sexes.

Young Caenorhabditis elegans hermaphrodites use their own sperm to protect against the negative consequences of mating.

How to Make a Weed: The Saga of the Slender False Brome Invasion in the North American West and Lessons for the Future

Abstract Historical herbarium collections and genetic analyses indicate that slender false brome (Brachypodium sylvaticum) was first introduced in test gardens in Oregon in the early 1900 s as part of the USDA’s plant introduction program. A small number of naturalized populations were established, but it was not until several decades later that this alien species became an aggressive invader. The Oregon invasive strains of false brome were generated as a consequence of mating among genetically divergent lineages. The resulting hybrid populations contained high levels of genetic variation that fueled the evolution of specific adaptations to the Pacific Northwest climate and ultimately generated genetically superior lineages. Although the false brome invasion has caused significant ecological and economic harm and is expected to continue spreading across western North America, understanding the circumstances that have promoted its success may provide valuable lessons for the management of native plants under pressure from global climate change.

Implications of mating system and pollen dispersal indices for management and conservation of the semi-arid species Prosopis flexuosa (Leguminosae)

Recruitment by fencing of semi-arid trees is a common woodland conservation strategy that may have both positive and negative implications. Domestic herbivores can act as efficient dispersal seed agents but they can also affect the survival and growth of the trees first stages. Prosopis flexuosa (algarrobo) woodlands represent the most important plant community in the Monte region in Argentina and as this resource is affected by deforestation, grazing, natural fires and replacement of natural ecosystems by croplands, in order to protect the “algarrobo” a reserve had been established. As efficient management and conservation program depends on the information on population structure and mating system, the objectives of this work were to estimate mating and pollen dispersal patterns in a wild P. flexuosa population from the Ñacuñan fenced to exclude domestic cattle for 40years. This population is mainly outcrosser (tm=0.996), sensitive to inbreeding depression at seed stage, having relative reduced pollen mediated gene dispersal distance (4.56–20.35m), which favors inbreeding as a consequence of mating between related individuals. Our results suggest that for ex situ conservation the distance that would be enough to avoid full sib sampling among harvested seed-trees is about 20m. Collecting seeds from different pods reduce the proportion of full sibs within progeny arrays. For in situ conservation it is important to take into account that forest patches separated by more than 250m are expected to be isolated, increasing the risk of genetic variability loss, inbreeding increase and population extinction. The results are discussed in reference to the “algarrobo” management program; while in some case excluding big mammals from the stands should be advisable, the interaction with long dispersal big herbivores might be considered as a strategy to promote increased outbreeding reducing the rate of mating between related individuals.

Cross-generational effects of male reproductive success and offspring immunocompetence inDrosophila melanogaster

In some species where males make no direct contribution to a female’s lifetime reproductive success, females choose mates based on the indirect benefits manifested in their offspring. One trait that may be subject to this sexual selection is immunocompetence (the ability to mount an immune response following exposure to pathogens); however, the results of previous work on its link to male attractiveness have been ambiguous. Herein we examine the life history consequences of mating with males with a history of failure or success in reproductive competitions in Drosophila melanogaster. By examining egg-to-adult survival, body weights, and bacterial loads of offspring reared in either the absence or presence of a bacterial pathogen, we were able to examine whether sire reproductive success was associated with their offsprings’ ability to respond to an immunological challenge and other life history traits. Our results are partially consistent with the predictions of the “immunocompetence handicap hypothesis”: competitively successful males (“studs”) sire male offspring that are better able to handle an immunological challenge than those sired by competitively unsuccessful males (“duds”). However, our assay also revealed the opposite pattern in female offspring, suggestive of the complicating presence of alleles with sexually antagonistic effects on the expression of this important life history trait.

Consequences of mating and predation risk for longevity in a freshwater snail: abstinence makes the heart beat longer.

Senescence is not a static property of an individual or population, but rather it is a dynamic process that may be influenced by environmental conditions. This can occur in at least two ways: in the long-term across multiple generations, and in the short-term via phenotypic plasticity. The former has attracted a lot of attention, both theoretically and empirically; the latter has lagged behind. To determine whether two important environmental variables (predation risk and mate availability) affect the pattern of actuarial senescence (i.e. the increase in mortality with age), we reared 30 full-sib families of the simultaneously hermaphroditic freshwater snail Physa acuta under four different environmental conditions and tracked individuals until death. Individuals were reared in a 2×2 factorial experiment that manipulated the nonlethal presence of chemical cues from predatory crayfish (presence/absence) and the opportunity to mate with an unrelated partner (mated/not mated). Snails that receive a partner reproduce by outcrossing, whereas those that remain in isolation can reproduce by self-fertilization. We compared the cumulative survival curves to test for an effect of predation risk and mating. The hazard ratio (HR) for the predation risk comparison was 1.042 indicating no significant difference between the curves. However, the HR for the mating comparison was 4.021, reflecting a significant reduction in survival probability for mated snails relative to isolated snails. As such, mating resulted in a much shorter lifespan, an outcome that we interpret in terms of shifting resource allocation.

Transcriptome Profiling of Sexual Maturation and Mating in the Mediterranean Fruit Fly, Ceratitis capitata

Sexual maturation and mating in insects are generally accompanied by major physiological and behavioural changes. Many of these changes are related to the need to locate a mate and subsequently, in the case of females, to switch from mate searching to oviposition behaviour. The prodigious reproductive capacity of the Mediterranean fruit fly, Ceratitis capitata, is one of the factors that has led to its success as an invasive pest species. To identify the molecular changes related to maturation and mating status in male and female medfly, a microarray-based gene expression approach was used to compare the head transcriptomes of sexually immature, mature virgin, and mated individuals. Attention was focused on the changes in abundance of transcripts related to reproduction, behaviour, sensory perception of chemical stimulus, and immune system processes. Broad transcriptional changes were recorded during female maturation, while post-mating transcriptional changes in females were, by contrast, modest. In male medfly, transcriptional changes were consistent both during maturation and as a consequence of mating. Of particular note was the lack of the mating-induced immune responses that have been recorded for Drosophila melanogaster, that may be due to the different reproductive strategies of these species. This study, in addition to increasing our understanding of the molecular machinery behind maturation and mating in the medfly, has identified important gene targets that might be useful in the future management of this pest.

Exploring the consequences of postmating–prezygotic interactions between the sexes

The role of male-female interactions in the divergence of postmating-prezygotic reproductive traits has recently focused on sexual conflict as the selective force. While an association between mating costs and benefits suggests that antagonistic interactions may be important, a mosaic of processes may actually mediate the evolutionary dynamics of postmating-prezygotic interactions. Our study examines the ecological relevance of mating effects on females. We test this critical but often overlooked assumption in desert Drosophila, where the species' ecology provides a framework for evaluating the evolutionary implications of such mating consequences. We show that mating has a profound impact on an ecologically critical character--desiccation resistance. To explore what selective factors might underlie the observed population differences in mating effects, we test whether trends in the data match predictions based on the species' ecology. While these preliminary data are consistent with the expectation that the mating benefits are positively correlated with environmental conditions, further examination reveals an additional unanticipated association with the reproductive environment. This unexpected association challenges existing assumptions regarding the forces driving divergence of traits involved in mating.

Variable Costs of Mating, Longevity, and Starvation Resistance inMusca domestica(Diptera: Muscidae)

Studies on conflict and cooperation in insect mating behavior usually assay the relative costs and benefits of mating in unreplicated experimental designs. We assayed multiple populations for such potential costs and benefits in Musca domestica L. under different nutritional environments. We used four populations, each derived from the same field site, ranging from six to 46 generations in the laboratory. Under benign environmental conditions (i.e., ad libitum food and water), mated females lived up to 13% longer than virgins, but this difference was not significant. Under extreme nutritional stress (i.e., no food or water), mated females lived significantly longer, but in only one of the populations tested. Under more moderate stress (i.e., water alone), mated females of one population died significantly earlier. Thus, aspects of both cooperation and conflict were found, but the effects were not repeatable across populations or nutritional environments. Overall, older females were more susceptible to stress. Moreover, the populations were significantly different in longevity (1.5-fold difference) and starvation resistance (2.2-fold difference). The youngest population lived longer, was more resistant to nutritional stress, and was the only line to exhibit significant costs of mating. Thus, the reduced selection pressures of the laboratory could have allowed the erosion of ejaculate toxicity, longevity, and starvation resistance. However, the simplest explanation is that replicate samples from a single geographic source population show appreciable among-line variation in fitness parameters and the consequences of mating. In conclusion, sexual selection studies on the costs and benefits of mating should consider environmental conditions, evolutionary history, and, perhaps most importantly repeatability.

Mating, seminal fluid components, and sperm cause changes in vesicle release in the Drosophila female reproductive tract.

Mating induces changes in female insects, including in egg production, ovulation and laying, sperm storage, and behavior. Several molecules and effects that induce these changes have been identified, but their proximate effects on females remain unexplored. We examined whether vesicle release occurs as a consequence of mating; we used transgenic Drosophila that allow monitoring of secretory granule release at nerve termini. Changes in release occur at specific times postmating in different regions of the female reproductive tract: soon after mating in the lower reproductive tract, and later in the upper reproductive tract. Some changes are triggered by receipt of sperm, others by male seminal proteins, and still others by the act of mating itself (or other unidentified effectors). Our findings indicate that the female reproductive tract is a multi-organ system whose regions are modulated separately by mating and mating components. This modulation could create an environment conducive to increased reproductive capacity.

Polygynous mating impairs body condition and homeostasis in male reindeer ( Rangifer tarandus tarandus )

Reindeer are polygynous ruminants that breed when plant growth declines in the Arctic. We studied seven males (2 years and older) in two herds with a total of 34 females to describe the costs and consequences of mating or rut. Body mass declined between September and November and did not recover through winter even though food was available ad libitum. Dominance did not affect body mass or any correlate of mass loss, indicating similar costs of rut among males. Males lost 34% of ingesta-free mass in 77 days of rut, which corresponded to depletion of 23% body protein and 78% body lipid. Water flux, plasma insulin, and plasma thyroxine were minimal 23 days after the peak in body mass, indicating low food intake. Maximum plasma testosterone and cortisol also followed peak mass and coincided with the death of two males from acute infections. Loss in body protein did not increase the ratio of urea to creatinine in plasma. Increased variance in plasma osmolality and urea during mass loss indicated altered homeostatic control during rut. Mating compromises survival of males through reduction of body reserves, food intake, and maintenance of tissues. These adverse effects may be the consequence of selection for large body size and aggression in a highly variable competition for mates.

Sexual size dimorphism in the two spot ladybird beetle Adalia bipunctata: developmental mechanism and its consequences for mating

Abstract 1. The literature on ladybirds indicates that males are consistently smaller than females but take the same length of time to complete their development. Rearing Adalia bipunctata at 20 and 25 °C confirmed that protandry cannot account for sexual size dimorphism in this species, nor can a difference in egg size.2. Female larvae consumed more food and had a higher relative growth rate in the fourth instar than did male larvae.3. When food is limited, small males appear to be more successful at mating than are large males.4. To account for these results, it is hypothesised that the gonads of male larvae compete more strongly with the soma for resources and that this reduces the growth potential of the soma of male larvae relative to that of female larvae. The greater mating success of small males when food is limited supports the eat or mate hypothesis, which predicts that when food is limited small males will spend less time feeding and more time mating than will large males.

A mortality cost of virginity at older ages in female Mediterranean fruit flies

Mortality rates were measured over the lifetime of 65,000 female Mediterranean fruit flies, Ceratitis capitata, maintained in either all-female (virgin) cages or cages with equal initial numbers of males, to determine the effect of sexual activity and mating on the mortality trajectory of females at older ages. Although a greater fraction of females maintained in all-female (virgin) cages survived to older ages, the life expectancy of the surviving virgins was less than the life expectancy of surviving non-virgins at older ages. This was due to a mortality crossover where virgin flies experience lower mortality than mated flies from eclosion to Day 20 but higher mortality thereafter. These results suggest that there are two consequences of mating—a short-term mortality increase (cost) and a longer term mortality decrease (benefit).

Mating and its effect on acoustic signalling behaviour in a primitive orthopteran, Cyphoderris strepitans (Haglidae): the cost of feeding females

Males of the primitive orthopteran, Cyphoderris strepitans, provide their mates with two types of nuptial food gift during mating: 1) females feed while coupled on the fleshy metathoracic wings of the male and the resultant flow of haemolymph and 2) the spermatophore transferred by the male includes a gelatinous spermatophylax which the female eats after mating. During the peak breeding interval, virgin males secure significantly more matings than their numbers relative to non-virgin males would predict. We tested the hypothesis that non-virgin males, having lost a substantial portion of available energy through previous investment in females, call significantly less than virgin males. Reduced calling should result in the attraction of fewer females and/or a greater risk of intrusion from competing males and consequently, a lowered mating success. Calling activity of male C. strepitans of varying mating status was monitored with a sound activated relay apparatus for two consecutive nights following their capture. Males were of three experimental groups, virgin, freshly wounded males (mated on the same night of capture), and old-wound males (mated at least one night prior to capture). Our cata showed a significant short-term reduction in signalling activity as a consequence of mating. Whereas there was no difference in the time spent calling by virgins on the first and second nights following capture, freshly wounded and oldwound males called significantly less on the first night than on the second. Furthermore, the proportion of males calling on both nights was significantly greater for the virgin and old-wound groups than for freshly wounded males. When the duration over which males called on the first night was compared with that of the second, virgin males showed no difference whereas old-wound males called for significantly shorter intervals on the first night. These results indicate that the cost of a large nutrient investment in females lowers the energy level in males below the threshold required for a prolonged signalling period. After a refractory interval during which males feed and replenish their energy reserves, calling levels equivalent to those which occur prior to mating are regained. Active female choice may also contribute to the reduced mating success of non-virgins, but this possibility remains untested.

Mating due to loss of surface exclusion as a cause for thermosensitive growth of bacteria containing the Rtsl plasmid.

At 25 degrees C, Rtsl+ bacteria grow to about 5 X 10(9) bacterial/ml before leveling off, whereas at 42 degrees C they grow from 2.6 X 10(8) bacteria/ml for only 2-3 generations after temperature shift before the growth is inhibited with a zig-zag pattern at the plateau. When diluted, Rtsl+ bacteria grow rapidly at 42 degrees C, until the concentration reaches as high as the undiluted 42 degrees C culture when growth measured by colony counts stops and the zig-zag pattern again appears. This density-dependent growth inhibition is not due to the presence of stable growth inhibitor(s). Mating experiments show that at 42 degrees C, Rtsl+ bacteria retain good donor ability; at the same time, they become good recipients in mating with Hfr (Rtsl) bacteria. SDS-PAGE reveals that membranes are altered at 42 degrees C. Examination of DNA synthesis indicates that chromosomal DNA is synthesized at both 25 degrees C and 42 degrees C at high bacterial concentration, but that of the Rtsl plasmid is slowed down at 42 degrees C. The labeling experiments suggest that in 2 h there are 2 rounds of plasmid replication at 25 degrees C, 3.5 rounds at 42 degrees C when bacteria are diluted, and 0.6 rounds at 42 degrees C when bacteria are not diluted. These results suggest that the growth inhibition of Rtsl+ bacteria at 42 degrees C is probably the consequence of mating initiated due to loss of surface exclusion.

MATING-TYPE FUNCTIONS FOR MEIOSIS AND SPORULATION IN YEAST ACT THROUGH CYTOPLASM

Given a nutritional regime marked by a low nitrogen level and the absence of fermentable carbon sources, conventional a/alpha diploid cells of Saccharomyces cerevisiae exhibit a complex developmental sequence that includes a round of premeiotic DNA replication, commitment to meiosis and the elaboration of mature tetrads containing viable ascospores. Ordinarily, haploid cells and diploid cells of genotype a/a and alpha/alpha fail to display these reactions under comparable conditions. Here, we describe a simple technique for sporulation of alpha/alpha and a/a cells. Cells of genotype alpha/alpha are mated to haploid a cells carrying the kar1 (karyogamy defective) mutation to yield heterokaryons containing the corresponding diploid and haploid nuclei. The kar1 strains mate normally, but nuclei in the resultant zygotes do not fuse. When heterokaryotic cells are inoculated into sporulation media, they produce asci with six spores. Four spores carry genotypes derived from the diploid nucleus and the other two possess the markers originating from the haploid nucleus, i.e., the diploid nucleus divides meiotically while the haploid nucleus apparently divides mitotically. Similarly, the a/a genome is "helped" to sporulate as a consequence of mating with alpha kar1 strains. The results allow us to conclude that the mating-type functions essential for meiosis and sporulation are communicated and act through the cytoplasm and that sporulation can be dissociated from typical meiosis. This procedure will facilitate the genetic analysis of strains that are otherwise unable to sporulate.

MATING PATTERN AND MATING SUCCESS OF DROSOPHILA PSEUDOOBSCURA KARYOTYPES IN LARGE EXPERIMENTAL POPULATIONS.

The pattern of matings between genotypes is the bridge connecting genotypic frequencies at the end of one generation with those at the beginning of the next. It is consequently an essential part of models in population genetics. The simplest assumption is that mating is random. The mating process in higher animals such as vertebrates and arthropods involves the pairing of diploid males and females and is random when the pairing occurs without regard to genotype. When mating is random and forces such as selection are absent, the genotypic frequencies among zygotes are the familiar Hardy-Weinberg frequencies. Most tests for randomness of mating are based on this fact. The usual procedure is to perform a chi-square test for goodness-of-fit between the frequencies of genotypes observed among zygotes and the Hardy-Weinberg expectations. However, such tests are indirect because they are based on genotypic frequencies which are the consequences of matings among adults of the previous generation, rather than on the frequencies of the matings themselves. And it is well known that the power of the chi-square test to detect departures from Hardy-Weinberg frequencies due to inbreeding (Ward and Sing, 1970) or selection (Lewontin and Cockerham, 1959) is severely limited. A stronger means of testing the randomness of mating is by direct analysis of the mating pattern-that is, by determination of the frequencies of matings between spe-

Somatic antigen 2 inheritance in Salmonella groups B and D.

Somatic (O) antigen 2 of Salmonella paratyphi A replaced somatic antigen 4 of an S. typhimurium recipient as the consequence of mating with an S. paratyphi A var. durazzo Hfr strain. The genetic determinants of these O antigens behaved in this cross as alleles of a common O locus, which is linked to the determinant of histidine biosynthesis, his. By employing phage lysates obtained by growth of P22 on an S. typhimurium hybrid which had received his and O-factor 2 determinants from the S. paratyphi A Hfr, it was possible to cotransduce the his and O-antigen 2 genes to both S. typhimurium and S. typhosa. S. typhimurium transductants which received somatic antigen 2 concurrently lost O-antigen 4, and S. typhosa transductants receiving O-antigen 2, lost their native O-antigen 9. These results indicate that the genetic determinants of O-antigens 2, 4, and 9 occupy the same O locus in S. paratyphi A, S. typhimurium, and S. typhosa, respectively, and are probably allelic.