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Reproductive Characteristics (reproductive + characteristic)
Selected AbstractsReduced reproductive success in small populations of the self-incompatible Primula vulgarisJOURNAL OF ECOLOGY, Issue 1 2004Rein Brys Summary 1Habitat fragmentation and the resulting decline in population size can affect biotic interactions and reproductive success of plant species. We investigated the impact of habitat type, population size, morph type and frequency, plant density, floral display and predation on different reproductive components in 16 populations of the distylous self-incompatible perennial herb, Primula vulgaris , a rare, declining species in Belgium. 2Although habitat type accounted for significant variation in population size, we did not find any relation between habitat type and either reproductive and vegetative characteristics. Population size, however, strongly affected reproductive success, such that plants in small populations produced significantly fewer fruits per plant and seeds per fruit, and therefore fewer seeds per plant. 3No significant difference was found between morph types for any reproductive characteristic, nor an interaction with population size. However, when morph frequency was strongly biased (, 1 : 3), the proportion of flowers setting fruit and the number of seeds per fruit were significantly lower in individuals of the common morph type. 4Within populations, individual plants varied tremendously in size and floral display. Total number of fruits per plant significantly increased with floral display, but the highest fruit set per flower was found at intermediate flower number. 5The proportion of fruit suffering pre-dispersal predation per plant significantly increased with floral display, but this did not offset the potential fitness gains of producing a large display. Furthermore, the absolute number of predated fruits per plant was significantly and positively affected by the interaction of the total number of fruits per plant and the density of the population. [source] Patterns of reproduction in two sympatric gerbil species in arid EgyptINTEGRATIVE ZOOLOGY (ELECTRONIC), Issue 2 2009Sohail SOLIMAN Abstract Despite a significant number of studies on the reproductive characteristics of small mammals, very little of this work has been conducted on species in Egpyt. Here, the Egyptian greater gerbil (Gerbillus pyramidum Saint-Hilaire, 1825) and Anderson's lesser Egyptian gerbil (Gerbillus andersoni De Winton, 1902) in northeastern Egypt were surveyed. Breeding behavior in these species was synchronized with rainfall in the winter and spring months. Surprisingly however, the removal of individual gerbils throughout the course of study resulted in an extension of reproductive activity into the dry summer and autumn months in the latter part of the sampling. These results are discussed in the context of density-dependent reproductive behavior in small mammals. [source] Aspects of the reproductive biology and breeding management of Asian and African elephants Elephas maximus and Loxodonta africanaINTERNATIONAL ZOO YEARBOOK, Issue 1 2006T. B. HILDEBRANDT Elephants possess many unique qualities, including some that relate directly to their reproductive biology. Thus, comparative studies on elephants provide valuable information to the growing biological database for extant mammals. Left undisturbed, Asian Elephas maximus and African Loxodonta Africana elephants reproduce well in the wild. It is ironic then that most captive populations face possible,extinction'because of historically poor reproductive performance. Some of the problems with breeding elephants in captivity are logistical but others, like ovarian and uterine pathologies and bull infertility, have management-related aetiology. Through advances in endocrine monitoring and ultrasound imaging techniques, we are beginning to understand some of the complex mechanisms controlling reproductive function in elephants. Several reproductive characteristics appear to be unique to the taxon, such as luteal steroidogenic function, follicular development patterns, pituitary gonadotrophin secretion, a 22 month-long gestation and musth (in ,,). One example is the,double LH surge'occurring 3 weeks apart during the follicular or non-luteal phase of the cycle, with only the second surge inducing ovulation. These qualities have at times both enhanced and hampered efforts to understand and control reproduction. We have learned that techniques developed for domestic or laboratory species are not always directly applicable to elephants. However, the recent success of artificial insemination based on new ultrasound and endocrine methodology offers hope that establishing selfsustaining populations is possible. This paper reviews our current knowledge of elephant reproduction and how it is being used to aid species conservation for maximal reproductive efficiency and enhancement of genetic management. [source] Estimation of gonad volume, fecundity, and reproductive stage of shovelnose sturgeon using sonography and endoscopy with application to the endangered pallid sturgeonJOURNAL OF APPLIED ICHTHYOLOGY, Issue 4 2007By J. L. Bryan Summary Most species of sturgeon are declining in the Mississippi River Basin of North America including pallid (Scaphirhynchus albus F. and R.) and shovelnose sturgeons (S. platorynchus R.). Understanding the reproductive cycle of sturgeon in the Mississippi River Basin is important in evaluating the status and viability of sturgeon populations. We used non-invasive, non-lethal methods for examining internal reproductive organs of shovelnose and pallid sturgeon. We used an ultrasound to measure egg diameter, fecundity, and gonad volume; endoscope was used to visually examine the gonad. We found the ultrasound to accurately measure the gonad volume, but it underestimated egg diameter by 52%. After correcting for the measurement error, the ultrasound accurately measured the gonad volume but it was higher than the true gonad volume for stages I and II. The ultrasound underestimated the fecundity of shovelnose sturgeon by 5%. The ultrasound fecundity was lower than the true fecundity for stage III and during August. Using the endoscope, we viewed seven different egg color categories. Using a model selection procedure, the presence of four egg categories correctly predicted the reproductive stage ± one reproductive stage of shovelnose sturgeon 95% of the time. For pallid sturgeon, the ultrasound overestimated the density of eggs by 49% and the endoscope was able to view eggs in 50% of the pallid sturgeon. Individually, the ultrasound and endoscope can be used to assess certain reproductive characteristics in sturgeon. The use of both methods at the same time can be complementary depending on the parameter measured. These methods can be used to track gonad characteristics, including measuring Gonadosomatic Index in individuals and/or populations through time, which can be very useful when associating gonad characteristics with environmental spawning triggers or with repeated examinations of individual fish throughout the reproductive cycle. [source] The distribution of South American galaxiid fishes: the role of biological traits and post-glacial historyJOURNAL OF BIOGEOGRAPHY, Issue 1 2004Víctor Cussac Abstract Aim, The aim of this work is to update the distribution data of Galaxiidae in South America, relating extant distribution to physiological and reproductive characteristics of the species, latitude, temperature, and post-glacial opportunities for colonization. Location, Lakes and rivers of Patagonia. Methods, We compared, and eventually reconsidered, general data about distribution based on the original literature about capture sites, incorporating several published and unpublished data to the analysis of the biological traits and distribution of Galaxiidae. Results, The more consistent issue in the comprehension of galaxiid biogeography in South America is the ability to establish landlocked populations. Different founding events in landlocked populations of Galaxias maculatus suggest the possible existence of older and younger landlocked populations. This difference in the time since the establishment of lacustrine populations could have been expressed in their ability for colonization of post-glacial areas. Galaxias maculatus, Aplochiton and Brachygalaxias are more clearly excluded from the post-glacial area than G. platei. For all the species we could note a more abundant record of lake populations at the area of glacial refuges. It could be noted that the most successful species, Galaxias platei, is a specialized deep bottom dweller. Deep bottom dwelling helps to endure winter constraints and it appears to be an alternative to the colonization of the littoral and limnetic zones of post-glacial lakes, the prefered habitat of the other Patagonian fish species. Main conclusions, At the end of this process of post-glacial colonization, in the beginning of twentieth century, man introduced several salmonid species in Patagonia. In addition, antropogenic actions had its more recent consequences in global warming. Nowadays we were able to observe new localities for Brazilian fishes into the Austral Subregion and expect some changes in the distribution of Galaxiidae. Northern limits for all species and southern limits for landlocked G. maculatus, Brachigalaxias bullocki and Aplochiton zebra, could be displaced southward. Probably, the species less affected by the changes will be G. platei. These predictions could be accurately formulated using the model of B.J. Shuter & J.R. Post (1990) Transactions of the American Fisheries Society119, 314,336, when biological database on these species are completed. [source] Effects of exploitation on reproductive capacity of blackspot snapper, Lutjanus fulviflamma (Pisces: Lutjanidae) in Mafia Island, TanzaniaAFRICAN JOURNAL OF ECOLOGY, Issue 4 2004A. T. Kamukuru Abstract There is paucity of information on the effects of exploitation on reproductive characteristics of blackspot snapper, Lutjanus fulviflamma (Forsskål 1775) in Tanzanian coastal waters. We compared size at first sexual maturity (LM50), sex ratio, fecundity, and breeding season of L. fulviflamma in least fished Mafia Island Marine Park (MIMP) and intensively fished areas (IFA) between May 1999 and April 2001. Fish in MIMP matured at significantly smaller size (female: LM50 = 206.3 mm; male: LM50 = 195.5 mm) than in IFA (female: LM50 = 216.7 mm; male: LM50 =212.1 mm) total body length. Sex ratio was balanced at 1.03 : 1 (female : male) in MIMP, but it was skewed 0.9 : 1 (female : male) in IFA. Size-related differences in sex ratio were observed with males predominating in the smaller sizes and females in the larger sizes. Total fecundity of fish in MIMP was determined at 45,200,430,200 oocytes in females of between 207 and 293 mm total length. Lutjanus fulviflamma in MIMP has a prolonged spawning season lasting from September to March peaking in December. None of the fish from IFA were in breeding state, suggesting recruitment overfishing is an added matter of concern for the long-term sustainability of the fishery at the current exploitation level. Résumé Il existe très peu d'informations sur les effets de l'exploitation sur les caractéristiques de la reproduction de Lutjanus fulviflamma (Forsskål 1775) dans les eaux côtières de Tanzanie. Nous avons comparé la taille au début de la maturité sexuelle (LM50), le sex-ratio, la fécondité et la saison de reproduction de L. fulviflamma dans le Parc Marin de l'Ile de Mafia (MIMP) où la pêche est moins intense et dans des eaux intensément exploitées (IFA) entre mai 1999 et avril 2001. Les poissons du MIMP deviennent mâtures tout en ayant une longueur totale significativement plus petite (femelles: LM50 = 206,3 mm; mâles: LM50 = 195,5 mm) que dans les IFA (femelles: LM50 = 216,7 mm; mâles: LM50 = 212,1 mm). Le sex-ratio est équilibréà 1,03/1 (femelles/mâles) dans le MIMP, mais il est de 0,9/1 (femelles/mâles) dans les IFA. On a observé des différences du sex-ratio liées à la taille, avec les mâles qui prédominent dans les plus petites tailles et les femelles dans les plus grandes. On a déterminé la fécondité totale dans le MIMP, entre 45.200,430.000 ovocytes à l'intérieur des femelles comprises entre 207 et 293 mm de longueur totale. Dans le MIMP, Lutjanus fulviflamma a une saison de frai prolongée, allant de septembre à mars avec un pic en décembre. Aucun des poissons des IFA n'était en période de reproduction, ce qui signifie une sur-pêche du potentiel reproducteur, ce qui est un motif d'inquiétude pour la durabilitéà long terme de la pêche à son niveau actuel. [source] Natural disturbance and life history: consequences of winterkill on fathead minnow in boreal lakesJOURNAL OF FISH BIOLOGY, Issue 3 2006A. J. Danylchuk Age, growth and reproductive characteristics of fathead minnow Pimephales promelas populations inhabiting four lakes that varied in the extent and frequency of winterkill were studied in the boreal region of western Canada. The lifespan of fathead minnows inhabiting lakes prone to winterkill was 1,2 years shorter than those in less disturbed lakes. In populations prone to winterkill, fish displayed faster growth rates and grew to a larger size-at-age, particularly during the first year of life. Although lower population densities in winterkill lakes probably contributed to this increased growth, adults in these populations tended to spawn earlier in the season than the smaller adults in more stable populations. Fathead minnows in lakes prone to winterkill also matured at an earlier age and allocated a greater proportion of their body mass to gonads than conspecifics in the more benign, stable lakes. These trends are consistent with predictions for organisms in variable, unpredictable environments and, because fathead minnows are tolerant to a wide range of environmental conditions, suggest that variation in life-history traits among populations is probably a product of both selection and phenotypic plasticity. [source] Phenology of the environmental weed Achillea millefolium (Asteraceae) along altitudinal and disturbance gradients in the Snowy Mountains, AustraliaNORDIC JOURNAL OF BOTANY, Issue 2 2004Frances Mary Johnston This study examined the phenology of the weed Achillea millefolium over a growing season in the Snowy Mountains. Vegetative and reproductive characteristics of plants in 1 m2 quadrats were compared among sites at four different altitudes (medium and high montane, low and high subalpine) and three types of infrastructure (primary road, secondary road and building, total 12 sites). Altitude, infrastructure and time of year did not affect percentage cover of vegetation. Flowering started earlier and lasted longer in the low montane sites compared to high subalpine sites. The type of infrastructure only affected the number of reproductive structures at the peak of flowering, with A. millefolium growing next to buildings having two to three times more inflorescences per m2 than along primary and secondary road verges. At the peak for each reproductive stage, there was an average of 1.47 developing inflorescences, 21 inflorescences in bud, 24 inflorescences in flower, 4 inflorescences setting seed, and 3 releasing seed. Based on the maximum number of inflorescences present at any time at each site, there was an average of 36 inflorescences, giving an estimate potential seed production of 51 400 seed per one m2 for A. millefolium in the Snowy Mountains. If the climate changes in the Snowy Mountains as predicted, then it is likely that yarrow will produce more inflorescences and seed in the higher altitude sites. [source] UNIQUE MANIRAPTORAN EGG CLUTCH FROM THE UPPER CRETACEOUS TWO MEDICINE FORMATION OF MONTANA REVEALS THEROPOD NESTING BEHAVIOURPALAEONTOLOGY, Issue 6 2008DARLA K. ZELENITSKY Abstract:, Egg clutches of non-avian maniraptoran theropods (Dinosauria) are rare, particularly in North America where those of Troodon formosus are the only maniraptoran clutches known. Here we describe a new partial maniraptoran clutch and nesting trace referred to Montanoolithus strongorum oogen. et oosp. nov. (Montanoolithidae oofam. nov.), from the Upper Cretaceous Two Medicine Formation of Montana. Based on a cladistic analysis of reproductive traits, we infer that this clutch belonged either to a caenagnathid or to a dromaeosaurid, which makes it the first clutch known of either taxon. This specimen preserves impressions and eggshell fragments of at least five eggs on a nest structure. The eggs are asymmetrical, paired, and lay radially in a ring configuration on the sloped sides of a bioturbated, flat-topped sandstone mound. Geology of the locality indicates the female nested in a poorly-vegetated area of freshly deposited sand, possibly near an active river channel. This clutch reveals that the egg-layer of Montanoolithus strongorum had a unique suite of reproductive characteristics and nesting behaviours among maniraptorans. [source] Reproductive ecology of the freshwater red alga Batrachospermum delicatulum (Batrachospermales, Rhodophyta) in three tropical streamsPHYCOLOGICAL RESEARCH, Issue 3 2005Orlando Necchi Junior SUMMARY Batrachospermum delicatulum specimens from three stream segments were analyzed from a tropical region in south- eastern Brazil (20°18,, 20°49,S, 49°13,, 49°46,W). Physical and chemical parameters and the spatial placement of thalli were investigated along with the reproductive characteristics of the gametophytic phase. Sequence data of the cox 2- 3 spacer region was also utilized to evaluate genetic variation in individuals within and among stream segments. Gametophyte occurred under relatively diverse environmental conditions, whereas thalli abundance was weakly or not correlated to environmental variables within the stream segments. All specimens examined were dioecious. The ratio of male/female plants was relatively low (0.5 to 1.3) and male plants tended to occur as clumps (two or three plants together). High reproductive success was observed, as indicated by the occurrence of 100% fertilized (carposporophytic) female plants. This is similar to previous reports for this and other dioecious species, which is remarkable considering the relatively low proportion of male/female plants. Results support the two hypotheses to explain the high reproductive success in dioecious species. The occurrence of male plants in clumps was evidence for a strict spatial relationship (i.e. male plants located in upstream position of female plants in order to release spermatia, which would be carried by eddies through female plants). In contrast, the occurrence of male and female plants adjacent to each other allowed outcrossing among neighboring plants with intermingled male and female branches, which seemed more applicable to some situations (low turbulence habitats). The cox 2- 3 spacer region from the 18 individuals sequenced was 376 bp and the DNA sequence was identical with no base pair substitutions. Likewise, a previous study of another Batrachospermum species showed that the same haplotypes were present in all stream segments from the same drainage basin, even though the stream segments were a considerable distance apart. Short distance dispersal either by small birds or waterway connectivity might explain these findings. [source] Reproductive adaptations to a large-brained fetus open a vulnerability to anovulation similar to polycystic ovary syndromeAMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 3 2003Deborah K. Barnett During the ovarian or menstrual cycle, prior to ovulation, many female primates exhibit a relatively prolonged follicular phase and terminate the postovulatory luteal phase with menstrual bleeding. The prolonged follicular phase is a trait that distinguishes primate from nonprimate species. It enables extended estrogen-induced proliferation and growth of the uterine endometrium prior to progesterone-induced maturation during the luteal phase to accommodate a potential pregnancy with a rapidly invading placenta. Progressive development of both an extended duration of estrogen-induced, preimplantation endometrial proliferation and a rapidly invading placenta across the Primate order may well have been necessary to accommodate differentiation and growth of an increasingly large fetal brain. Prolongation of the follicular phase in primates has also led to the isolation of the final stages of follicle selection (growth deviation of the dominant follicle from its contemporaries) solely within the follicular phase and thus outside the protection of luteal phase progesterone inhibition of pituitary luteinizing hormone (LH) secretion. Such primate reproductive characteristics put the latter stages of ovarian follicle selection at risk of exposure to excessive pituitary secretion of LH. Excessive secretion of LH during follicle selection could result not only in impaired follicle development, excessive ovarian androgen secretion, and ovulation failure, but also in excessive estrogenic stimulation of the uterine endometrium without intervening menstrual periods. Such reproductive abnormalities are all found in a single, prevalent infertility syndrome afflicting women in their reproductive years: polycystic ovary syndrome (PCOS). We propose that successful female reproductive adaptations to accommodate the growth demands of large-brained primate fetuses have facilitated a particular vulnerability of higher primates to hypergonadotropic disruption of ovulatory function, as found in PCOS. Am. J. Hum. Biol. 15:296,319, 2003. © 2003 Wiley-Liss. [source] Reciprocal effects in true potato seed breeding in short-day length environmentsPLANT BREEDING, Issue 4 2003A. M. Golmirzaie Abstract Reciprocal crosses may have significantly distinct performances regarding tuber characteristics in potato, suggesting the importance of cytoplasmic effects in this crop. The selection of parents for true potato seed breeding therefore needs to consider this potential effect when determining the direction of a cross. The aim of this research was to determine whether a broad-based true potato seed breeding population, developed at the Centro Internacional de la Papa, could be affected by cytoplasmic effects in the short-day length environments of the tropics. Two random sets of reciprocal biparental crosses were included in the first set of experiments, which were grown in two contrasting Peruvian locations. Only one out of 14 reciprocal crosses showed significantly distinct performance for tuber yield and tuber set. In the second set, only one of each of the 12 reciprocal crosses had distinct performance for vine earliness, days to flowering and flowering intensity, but four of the reciprocal crosses in the second set showed distinct pollen production. The results suggest that cytoplasmic effects in this breeding population are more important for reproductive characteristics such as pollen production than for tuber yield. This finding is not surprising because male sterility in potato results from the interaction between sensitive cytoplasm and dominant nuclear genes. [source] Patterns of reproduction in Malayan silvered leaf monkeys at the Bronx ZooAMERICAN JOURNAL OF PRIMATOLOGY, Issue 10 2009Nichole Shelmidine Abstract Within phylogenetic limits reproductive characteristics of a given species may vary between populations in response to ecological and social factors. For instance, in environments where high quality nutrition is readily available, the onset and speed of reproduction are often accelerated. Other influencing factors might be maternal experience or the sex of the infant. Here we present data on reproductive characteristics for the silvered leaf monkey (Trachypithecus cristatus), a medium-sized Asian colobine housed at the Wildlife Conservation Society's Bronx Zoo as a one-male group. To place the species into an appropriate phylogenetic context, we limited our comparison to other colobine species. Demographic data span 21.4 years (October 1985 to March 2007) and derive from 30 adult females (128.0 female years). Detailed behavioral data stem from a 2.2 years study (November 2002 to January 2005; 734 days, 4,225,hr). As in other Asian colobines, receptive periods were short (mean=4.3 days, n=68). This is expected for one-male groups where receptivity likely indicates, rather than conceals, ovulation. Gestation length was estimated based on a change in the pattern of sexual behavior (mean=194.6 days, n=7). It fell within the range reported for the taxon. Births occurred year round, at an early age (mean=2.9 years, n=8), at short intervals (mean=14.9 months, n=59) in combination with a short lactation (mean 12.1 months, n=9) likely due to the nearly unlimited availability of nutrition in this zoo setting. Primiparous females tended to have a longer first interbirth interval but infant survival rates were similar to multipara possibly due to the absence of predators. Maternal investment was independent of the infant's sex and birth sex ratio was even. Our results emphasize that when interpreted with caution, zoo populations yield realistic reproductive characteristics that can help fill the gap in our knowledge about colobine life history. Am. J. Primatol. 71:852,859, 2009. © 2009 Wiley-Liss, Inc. [source] Cybrids and tetrad sterility for developing true potato seed hybridsANNALS OF APPLIED BIOLOGY, Issue 2 2003ALI M GOLMIRZAIE Summary Potato cybrids result from the fusion between cytoplasm and nuclear gene donors. Such genetic materials are an alternative means to broaden the breeding pool by non-sexual gene transfer. Tetrad pollen sterility provides also another source of male sterility with some potential for true potato seed breeding. The objective of this research was to investigate cybrid-derived offspring for both agronomic and reproductive characteristics in two contrasting Peruvian locations, and to examine new exotic germplasm for tetrad sterility, with the aim of broadening the breeding pool available at the Centro Internacional de la Papa (CIP). The cybrids were derived from fusions between Y-245.7, a clone with tetrad sterility, and Atzimba. These cybrids were crossed with selected male parents from the CIP breeding population, and their hybrid offspring were tested in La Molina (coastal desert) and Huancayo (cool highlands). In addition, other clones with tetrad sterility were also crossed with selected testers to determine their breeding value. There were significant differences for tuber yield, style length, and berry number among the hybrid offspring, and the genotype by environment interaction was significant for tuber yield and berry number. The top 25% highest yielding cybrid-derived offspring across both locations showed the same tuber yield although they were significantly different for some of the reproductive characteristics. With the exception of one cybrid, the others did not exhibit segregation for tetrad sterility in their hybrid offspring, which were male fertile. However, the offspring derived from crosses between other sources of tetrad sterility and the same testers all showed tetrad sterility, and some of them had outstanding tuber yield at La Molina. The lack of segregation for tetrad sterility in these new crosses suggests that the non-cybrid, male sterile, female parents are triplex or quadriplex for the Tr nuclear locus, which interacts with a sensitive cytoplasm (e.g. Trs from S. verrucosum or S. stoloniferum) to produce tetrad sterility in potato. [source] Development of germ cells and reproductive biology in the sipunculid Phascolosoma esculentaAQUACULTURE RESEARCH, Issue 3 2009Xue-Ping Ying Abstract Sipuncula are of increasing interest for fisheries and aquaculture in China. Sustainable harvests will rely on a better knowledge of reproductive characteristics and stock enhancement. Here, we investigated the structural characteristics of and seasonal changes in germ cell development of the sipunculid Phascolosoma esculenta from the south-eastern coast of Zhejiang, China. An annual survey of egg numbers in the coelom (body cavity) fluid by light and electron microscopy of the females indicates that P. esculenta is dioecious. No defined gonad but dissociated germ cells were found in the coelomic cavity during the 1-year observation. The germ cells showed multiplication and development in the coelomic cavity. Reproduction took place from May to September, with a peak in July and August. The oogenesis can be divided into four phases: cell proliferation, pre-vitellogenesis, vitellogenesis and egg envelope formation and maturation. The process of spermatogenesis can also be divided into four phases: cell multiplication, cell growth, cell maturation and metamorphosis. Monthly changes in the relative number of eggs in each stage indicate that P. esculenta lays eggs in batches. The sperm thrives in the coelomic fluid in the form of cell groups with patterns of genesis and release similar to those of the eggs. Eggs of P. esculenta were fertilized only when reaching the nephridium. The sex ratio was about 1:1 throughout the year. [source] | ||||||||||||||||||||||