Male Reproductive Characters Research Articles

Contribution to the Embryology, Sporoderm and Spermoderm Pattern of <I>Bothriochloa pertusa</I> (L.) A. Camus, <I>Capillipedium filiculme</I> (Hook.F.) Stapf and <I>Dichanthium annulatum</I> (Forssk.) Stapf with a Brief discussion on its Taxonomic Status

Embryological features in Bothriochloa pertusa, Capillipedium filiculme and Dichanthium annulatum have been studied. The male reproductive characters are constant as evidenced by anther wall development and it corresponds to Monocot type. At maturity the pollen grains are 3-celled. Embryo sac development and embryogeny conforms to Polygonum type and Asterad type respectively. Endosperm, seed coat and pericarp have been studied and data on SEM investigation on pollen wall and seed coat of these taxa are added. The three taxa viz., Bothriochloa, Capillipedium and Dichanthium were considered under Andropogoneae of Panicoideae as separate genera by Bor (1960). De Wet and Harlan (1970) merged them in Dichanthium . The evidences given by them are intergeneric hybridization and production of fertile hybrids between these three genera. Clayton (1977) also followed the concept of merger taking priority. The authors assessed the possibility of merger into Dichanthium on the basis of embryology, sporoderm and spermoderm pattern

Penis morphology facilitates identification of cryptic African bat species

AbstractAfrica hosts a high number of bat species, many of which have been poorly studied. Among African vesper bats (Vespertilionidae), some species are morphologically similar to each other, hampering identification in the field. Consequently, basic information on these species’ population dynamics, distributions, or behaviors is vague and/or incorrectly documented. Among some Vespertilionidae, variation in flaccid penis shape enables species identification. This variation in morphology is thought to have resulted from sexual selection operating on the erect penis. Furthermore, in the context of strong postcopulatory competition, divergence in sperm traits may have evolved among closely related species. These male reproductive characters have hitherto not been investigated in southern African vespertilionid bats. In this study, we present the morphology of flaccid penis, erect penis, and sperm, of six small vesper species, based on the prediction that these characters have evolved sufficiently toward different optima to allow species discrimination. Species identification based solely on the morphological characters of the penis entirely matched species identification based on traditional (craniodental) characters. We illustrate penis morphology of these species to assist with field identifications for future ecological, conservation, or behavioral studies. Sperm morphology was sufficient to discriminate between the different genera, but could not reliably separate Neoromicia nana, Ne. zuluensis, and Ne. capensis. Hence, we demonstrate that these difficult to identify species can be readily distinguished based on traits directly observable in the field and on living animals, which will lead to more focused field studies on these otherwise morphologically cryptic species. Finally, our comparisons of penis morphology support the suggestion that Hypsugo anchietae is better placed within the genus Neoromicia.

Inbreeding reveals mode of past selection on male reproductive characters in Drosophila melanogaster

Directional dominance is a prerequisite of inbreeding depression. Directionality arises when selection drives alleles that increase fitness to fixation and eliminates dominant deleterious alleles, while deleterious recessives are hidden from it and maintained at low frequencies. Traits under directional selection (i.e., fitness traits) are expected to show directional dominance and therefore an increased susceptibility to inbreeding depression. In contrast, traits under stabilizing selection or weakly linked to fitness are predicted to exhibit little-to-no inbreeding depression. Here, we quantify the extent of inbreeding depression in a range of male reproductive characters and then infer the mode of past selection on them. The use of transgenic populations of Drosophila melanogaster with red or green fluorescent-tagged sperm heads permitted in vivo discrimination of sperm from competing males and quantification of characteristics of ejaculate composition, performance, and fate. We found that male attractiveness (mating latency) and competitive fertilization success (P2) both show some inbreeding depression, suggesting they may have been under directional selection, whereas sperm length showed no inbreeding depression suggesting a history of stabilizing selection. However, despite having measured several sperm quality and quantity traits, our data did not allow us to discern the mechanism underlying the lowered competitive fertilization success of inbred (f = 0.50) males.

Sperm competition, immunity, selfish genes and cancer.

Sperm competition is widespread and has played an important role in shaping male reproductive characters such as testis size and numbers of sperm produced, and this is reflected in the rapid evolution of many reproductive genes. Additionally, sperm competition has been implicated in the rapid evolution of seminal fluids. However, our understanding of the molecular basis of many traits thought to be important in sperm competition is rudimentary. Furthermore, links between sperm competition and a range of issues not directly related to reproduction are only just beginning to be explored. These include associations between sperm competition and selfish genes, immunity and diseases such as cancer.We briefly review these topics and suggest areas we consider worthy of additional research.

EFFECTS OF FOLIAR HERBIVORY ON MALE AND FEMALE REPRODUCTIVE TRAITS OF WILD RADISH,RAPHANUS RAPHANISTRUM

In this study, we examined how foliar herbivory affected the relative allo- cation to male and female reproductive traits in a hermaphroditic plant. In two experiments, one in the greenhouse and the other in a growth chamber, leaves of full sibling plants of the annual wild radish, Raphanus raphanistrum, received one of four damage treatments to leaves (0, 25% (two types), or 50% leaf area removal). We controlled natural damage by Pieris rapae larvae through the use of clip cages. Measurements of both male and female reproductive characters were made on a series of flowers produced by each plant over its lifetime. We measured pollen production, pollen size, ovule number, ovule size, petal size, nectar production, and sugar content. Effects of herbivory on plant phenology were also assessed. At the end of the experiment, we quantified total flower production, fruit pro- duction, number of seeds and fruit, and seed and vegetative biomass. In general, male reproductive characters were more affected than female characters by herbivory. Leaf herbivory reduced pollen number and pollen size, whereas ovule size and number were not affected. Petal size, which we also classify more as a male trait, decreased with herbivory. Plants were generally able to completely compensate for herbivory in the total number of flowers and fruit they produced; however, fewer fruits were found in the heaviest damage treatment in the growth chamber experiment. We discuss alternative ex- planations for this pattern based on developmental constraints and adaptive responses. In summary, male fitness traits were much more strongly affected by herbivory than were female traits; full compensation in seed production after herbivory may come at the cost of male reproductive success in these hermaphroditic plants.

Estimates of hierarchical variation in flower morphology in natural populations ofScleranthus annuus (Caryophyllaceae), an inbreeding annual

The variation in two sets of morphological characters of the flowers of the highly inbreedingScleranthus annuus (Caryophyllaceae) was assessed using 15–20 plants from each of 20 natural populations from the southernmost region of Sweden. The stamen fertility data set consisted of 10 characters describing the degree of fertility of the ten stamens/staminoids, while the sepal/gynoecium data set comprised 10 sepal characters, together with style and stigma length. Substantial variation was found in both the degree of development and the fertility of the stamens, the degree of variability in stamen fertility being related to stamen position within the flower. Considerable variation was found in the characters of the sepal and the gynoecium. Hierarchical analyses of variance indicated that 29% of the variation in total male reproductive effort was distributed among populations, 28% among plants within populations and 43% represented within-plant variation. The corresponding averages for the characters from the sepal/gynoecium data set are 26, 38, and 35%: a greater proportion of the total variance in female reproductive characters is accounted for by among individual variation than is the case with the male reproductive characters. Significance tests of Mahalanobis’ distances derived by canonical variate analyses indicated that all populations were significantly separated using the sepal/gynoecium data set, while only 50% of the pairwise comparisons on the basis of the stamen fertility data set were significant. Cluster analysis did not reveal any aggregation of the populations. The incongruence of the two data sets and their ability to discriminate between the populations is discussed.