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Reproductive Patterns (reproductive + pattern)
Selected AbstractsCohort Reproductive Patterns in Low-Fertility CountriesPOPULATION AND DEVELOPMENT REVIEW, Issue 1 2001Tomas Frejka This account reports on a project in progress that aims to obtain a comprehensive picture of contemporary fertility levels and trends in 27 low-fertility countries. Cohort analysis is applied to review the fertility experience of women born from the 1930s through the 1970s. This choice of dates ensures that not only completed fertility but also the fertility patterns of women in the midst of or near the onset of their reproductive period are examined. In most of the 27 countries, completed fertility of successive cohorts has been declining. It appears plausible that the trends discerned in the analysis will continue in the foreseeable future. For these trends to be reversed, women who are about to enter or who are in the midst of their reproductive periods would have to adopt fertility patterns markedly different from those of women born in the 1960s and 1970s. [source] Reproductive patterns of Caloglossa species (Delesseriaceae, Rhodophyta) from Australia and New Zealand: multiple origins of asexuality in C. leprieurii.PHYCOLOGICAL RESEARCH, Issue 3 2001Literature review on apomixis, bisexuality, mixed-phase, sexual compatibility SUMMARY Reproduction and life history patterns in culture of five Caloglossa speaes from Australia and New Zealand are compared. Caloglossa adhaerens King et Puttock and Caloglossa bengalensis (Martens) King et Puttock have a Polyslphonla-type sexual life history (P-type, isomorphic alternation of generations). Caloglossa monosticha Kamiya occurs only in Western Australia (WA) and is a P-type. Caloglossa ogasawaraensis Okamura occurs in WA, Northern Territory (NT), Queensland (QLD), New South Wales (NSW), Victoria (VIC) and South Australia (SA) and is for the most part a P-type in culture. A few isolates have bisexual gametophytes that are self-compatible, while most are unisexual. Caloglossa ogasawaraensis from Adelaide, SA and from Wilsons Promontory, VIC are new records for these States. In Australia, Caloglossa postiae (King et Puttock) Kamiya et King occurs in NSW, NT and QLD. All nine isolates are P-type. Isolates of Caloglossa leprieurii (Montagne) G. Martens from NSW, NT, QLD, Tasmania, VIC and New Zealand are P-type except for the freshwater isolates in which tetraspore germlings do not reproduce. In some isolates mixed-phase reproduction is seen with male gametophytes producing both viable spermatia and tetrasporangia and female gametophytes producing procarps and sori with non-dividing sporangia. All isolates of C. leprieurii irom Spencer Gulf and Gulf of St Vincent, SA and one isolate from QLD give rise to successive asexual generations of tetrasporophytes. Based on RuBisCO spacer DNA data an asexual life history has arisen several times in the C. leprieurii complex. The literature on apomixis, mixed-phase reproduction, bisexuality and sexual compatibility in red algae is surveyed. [source] Long-term reproductive behaviour of woody plants across seven Bornean forest types in the Gunung Palung National Park (Indonesia): suprannual synchrony, temporal productivity and fruiting diversityECOLOGY LETTERS, Issue 10 2007Charles H. Cannon Abstract For 68 months, we observed the reproductive behaviour of 7288 woody plants (172 figs, 1457 climbers and 5659 trees) spanning major soil and elevational gradients. Two 2,3 month community-wide supra-annual fruiting events were synchronized across five forest types, coinciding with ENSO events. At least 27 genera in 24 families restricted their reproduction to these events, which involved a substantial proportion of tree diversity (> 80% of phylogenetic diversity). During these events, mean reproductive levels (8.5%) represented an almost four-fold increase compared with other months. These patterns indicate a strong behavioural advantage to this unusual reproductive behaviour. Montane forest experienced a single, separate fruiting peak while the peat swamp forest did not participate. Excluding these events, no temporal reproductive pattern was detectible, at either the landscape or forest type. These phenological patterns have major implications for the conservation of frugivore communities, with montane and swamp forests acting as ,keystone' forests. [source] Oestrous occurrence in captive female Cricetomys gambianus (Rodentia: Cricetidae)JOURNAL OF ZOOLOGY, Issue 3 2002M. Malekani Abstract Cricetomys gambianus is an important source of protein for human consumption in many parts of sub-Saharan Africa. Wild populations are under considerable hunting pressure, suggesting that captive rearing may be desirable. Successful captive-breeding programmes require a better understanding of reproductive physiology and behaviour. Eight groups containing a total of 68 C. gambianus females were used to characterize the reproductive pattern, including the occurrence and duration of oestrus, the cycle length, the oestrous cyclicity and the mode of ovulation. These female groups were kept in different social and physical environments and examination of vaginal smears were carried out at different periods. Results of the vaginal cytology examination showed two characteristic stages of the cycle: ,oestrus' and ,anoestrus'. Oestrus appeared on average 1.3 times only in one female during 1 month, but its occurrence varied between 0.4 and two times in a month. The mean oestrous length was 3.3 days and ranged from 1.4 to 7.8 days. The average cycle length was 7.9 days but varied between 3 and 15 days. These results showed an irregular cycle pattern and revealed that C. gambianus may be an induced ovulator. Housing events, such as the presence or the absence of a male and the type of cages or rearing room, and the dry and the rainy seasons did not seem to influence the cycle pattern in this species. Further investigations on the basic reproductive biology of Cricetomys are necessary to provide the basis for developing farming methods that will yield high productivity. [source] Fitness consequences of host selection in ectoparasites: testing reproductive patterns predicted by isodar theory in fleas parasitizing rodentsJOURNAL OF ANIMAL ECOLOGY, Issue 5 2004BORIS R. KRASNOV Summary 1Fleas Xenopsylla conformis and Xenopsylla ramesis parasitize the rodents Meriones crassus and Gerbillus dasyurus. Previously reported isodar analysis of host selection suggested that at low density, X. conformis parasitizes M. crassus only, but with an increase in flea density, G. dasyurus is also parasitized. Xenopsylla ramesis at low density parasitizes both hosts equally, whereas at high density prefers M. crassus. The ultimate cause of underlying these patterns was suggested to be differential fitness reward of parasitism on a particular host species, while the mechanism can be adaptive host selection by fleas. 2To justify the suggested fitness,density relations, we studied reproductive success in X. conformis and X. ramesis feeding on either M. crassus or G. dasyurus. We hypothesized that reproductive success would differ between two host species for each flea species. 3Xenopsylla conformis parasitizing M. crassus produced more eggs than when parasitizing G. dasyurus, whereas time of oviposition and larval hatching did not depend on host species. In contrast, egg production in X. ramesis did not differ between host species. However, fleas fed on M. crassus needed fewer bloodmeals, oviposited earlier and hatching of their larvae took less time than those of fleas fed on G. dasyurus. 4Patterns of egg production and development time in both fleas were consistent with the hypothesis that their between-host distribution arose from adaptive host selection strategy. [source] Reproductive life history of Thornicroft's giraffe in ZambiaAFRICAN JOURNAL OF ECOLOGY, Issue 2 2010Fred B. Bercovitch Abstract Knowledge of the reproductive life history of giraffe in the wild is sparse. Giraffe have two fairly unusual reproductive patterns among large mammals: they can become pregnant while lactating, and calf mortality is extremely high. Longitudinal records are largely absent, so tracking reproductive parameters tends to combine information from captive and field studies. In this study, we examine longitudinal data obtained over a 33-year period in one population of Thornicroft's giraffe in order to chart their reproductive careers. We found that age at first parturition was 6.4 years, or slightly later than in captivity. Giraffe bred throughout the year, with cows producing offspring on average every 677.7 days. About half of the calves died before one year of age, but death of a calf did not reduce interbirth interval. We conclude that the lifetime reproductive success of giraffe is more dependent on longevity and calf survivorship than on reproductive rate. Résumé La connaissance de la biologie reproductive de la girafe dans la nature est lacunaire. La girafe présente deux schémas de reproduction plutôt inhabituels chez les grands mammifères : elles peuvent être fécondées tout en allaitant, et la mortalité du jeune est extrêmement élevée. On manque cruellement de rapports longitudinaux, c'est pourquoi la recherche des paramètres de la reproduction a tendance à combiner les informations provenant d'études réalisées en captivité et sur le terrain. Dans ce rapport, nous examinons les données longitudinales recueillies sur une période de 33 ans dans une population de girafes de Thornicroft afin de dresser le tableau de leur carrière reproductive. Nous avons découvert que l'âge de la première parturition était de 6,4 ans, ou légèrement plus tard en captivité. Les girafes se reproduisent toute l'année, et les femelles mettent bas en moyenne tous les 677,7 jours. Près de la moitié des jeunes meurent avant l'âge d'un an, mais la mort du jeune ne réduit pas l'intervalle entre deux naissances. Nous concluons que la réussite de la vie reproductive d'une girafe dépend davantage de sa longévité et de la survie des jeunes que du taux de reproduction. [source] The role of rainfall and predators in determining synchrony in reproduction of savanna trees in Serengeti National Park, TanzaniaJOURNAL OF ECOLOGY, Issue 1 2007SIMON A. R. MDUMA Summary 1We examined the factors determining synchrony in reproduction in nine Acacia and six other tree species in the Serengeti ecosystem. 2We test two hypotheses: (i) an abiotic hypothesis where the primary determinant of synchrony is an adaptation to water availability; and (ii) biotic hypotheses where these adaptations to water can be further refined by additional adaptations to avoid predators, or attract seed and fruit dispersers. 3Flowering and fruiting were recorded monthly for individually marked trees during 1997,2004. Flowering in different species occurs semi-annually, annually or, in the case of one species, once every 2 years. For most species synchrony of flowering was correlated with seasonal rainfall, with lags related to the mean height of the species; small species flowered during the rains while larger species flowered in the dry season. Fruiting seasons occurred at the end of the rains irrespective of the flowering season. 4Most species showed flowering synchrony greater than expected from the distribution of rainfall. This may be related to avoidance of insect seed predators through predator satiation. Two Acacias showed multi-annual fruiting (masting), possibly as a predator avoidance mechanism. Acacia tortilis has two flowering seasons: a dry season flowering with early abortion of pods and a wet season flowering producing successful fruits. 5Two species of Commiphora appeared to be synchronized so as to attract birds that disperse seeds. Acacia tortilis produced indehiscent pods attractive to ungulates, possibly to kill bruchid beetles during digestion and so increase seed viability. 6Our results suggest that synchrony in these trees is caused by a strong interaction between abiotic and biotic factors. Closely related species have different reproductive patterns of synchrony that seem to be adapted to different combinations of rainfall, predators and dispersers. Rainfall is the primary determinant but the activities of predators and dispersers increase the degree of synchrony. [source] HABITAT DIFFERENCES IN THE TIMING OF REPRODUCTION OF THE INVASIVE ALGA SARGASSUM MUTICUM (PHAEOPHYTA, SARGASSACEAE) OVER TIDAL AND LUNAR CYCLES,JOURNAL OF PHYCOLOGY, Issue 1 2009Carla Monteiro Sargassum muticum (Yendo) Fensholt is an invasive species that is firmly established on intertidal and subtidal rocky shores of Europe and the Pacific coast of North America. Local success and spread of S. muticum is thought to rely on its reproductive potential that seems dependent on exogenous factors like tidal and lunar cycles. This study is the first to compare the reproductive patterns (periodicity of egg expulsion and embryo settlement) of this invader in two different habitats: the middle and low intertidal. The combination of monthly, daily, and tidal samples at triplicate sites within each habitat showed a semilunar periodicity of egg expulsion and embryo settlement coincident with increasing tidal amplitude just before full and new moons. In both habitats, duration of each egg expulsion event was ,1 week, and embryo settlement occurred during the first daily low tide and with the incoming high tide during spring tides. However, both expulsion and settlement started 1,2 d earlier, expulsion saturation was faster, and settlement was higher in the mid- compared to the low intertidal. Our results suggest that the exact timing of gamete expulsion and embryo release of S. muticum responds to local factors, including tidal cues, which result in differences between mid- and low-intertidal habitats. [source] Dissecting components of population-level variation in seed production and the evolution of masting behaviorOIKOS, Issue 3 2003Walter D. Koenig Mast-fruiting or masting behavior is the cumulative result of the reproductive patterns of individuals within a population and thus involves components of individual variability, between-individual synchrony, and endogenous cycles of temporal autocorrelation. Extending prior work by Herrera, we explore the interrelationships of these components using data on individual seed production in 59 populations of plants from 24 species spanning a large range of annual variability, from species exhibiting strong masting to others with little annual variability in seed production. Estimates of population and individual variability were not biased by sample size or average overall seed production when based on untransformed seed production values, but these values declined as log-transformed seed production increased. Population variability was more strongly correlated with individual variability (r=0.86) than individual synchrony (r=0.73). These latter two components were also significantly correlated (r=0.45), but randomizations confirm that they need not covary closely. Thus, selection can act separately on inter-annual variability and between-individual synchrony. We illustrate the potential for such fine-tuned selection on seed production patterns by discussing several examples and by demonstrating significant differences in components of population-level variation in seed production among species related to their life-history. [source] Synchrony between growth and reproductive patterns in human females: Early investment in growth among Pumé foragersAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 2 2010Karen L. Kramer Abstract Life history is an important framework for understanding many aspects of ontogeny and reproduction relative to fitness outcomes. Because growth is a key influence on the timing of reproductive maturity and age at first birth is a critical demographic variable predicting lifetime fertility, it raises questions about the synchrony of growth and reproductive strategies. Among the Pumé, a group of South American foragers, young women give birth to their first child on average at age 15.5. Previous research showed that this early age at first birth maximizes surviving fertility under conditions of high infant mortality. In this study we evaluate Pumé growth data to test the expectation that if early reproduction is advantageous, then girls should have a developmental trajectory that best prepares them for young childbearing. Analyses show that comparatively Pumé girls invest in skeletal growth early, enter puberty having achieved a greater proportion of adult body size and grow at low velocities during adolescence. For early reproducers growing up in a food-limited environment, a precocious investment in growth is advantageous because juveniles have no chance of pregnancy and it occurs before the onset of the competing metabolic demands of final reproductive maturation and childbearing. Documenting growth patterns under preindustrial energetic and demographic conditions expands the range of developmental variation not otherwise captured by normative growth standards and contributes to research on human phenotypic plasticity in diverse environments. Am J Phys Anthropol, 2010. © 2009 Wiley-Liss, Inc. [source] The ecology and evolutionary endocrinology of reproduction in the human femaleAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue S49 2009Virginia J. Vitzthum Abstract Human reproductive ecology (HRE) is the study of the mechanisms that link variation in reproductive traits with variation in local habitats. Empirical and theoretical contributions from biological anthropology, physiology, and demography have established the foundation necessary for developing a comprehensive understanding, grounded in life history theory (LHT), of temporal, individual, and populational variation in women's reproductive functioning. LHT posits that natural selection leads to the evolution of mechanisms that tend to allocate resources to the competing demands of growth, reproduction, and survival such that fitness is locally maximized. (That is, among alternative allocation patterns exhibited in a population, those having the highest inclusive fitness will become more common over generational time.) Hence, strategic modulation of reproductive effort is potentially adaptive because investment in a new conception may risk one's own survival, future reproductive opportunities, and/or current offspring survival. The hypothalamic-pituitary-ovarian (HPO) axis is the principal neuroendocrine pathway by which the human female modulates reproductive functioning according to the changing conditions in her habitat. Adjustments of reproductive investment in a potential conception are manifested in temporal and individual variation in ovarian cycle length, ovulation, hormone levels, and the probability of conception. Understanding the extent and causes of adaptive and non-adaptive variation in ovarian functioning is fundamental to ascertaining the proximate and remote determinants of human reproductive patterns. In this review I consider what is known and what still needs to be learned of the ecology of women's reproductive biology, beginning with a discussion of the principal explanatory frameworks in HRE and the biometry of ovarian functioning. Turning next to empirical studies, it is evident that marked variation between cycles, women, and populations is the norm rather than an aberration. Other than woman's age, the determinants of these differences are not well characterized, although developmental conditions, dietary practices, genetic variation, and epigenetic mechanisms have all been hypothesized to play some role. It is also evident that the reproductive functioning of women born and living in arduous conditions is not analogous to that of athletes, dieters, or even the lower end of the "normal range" of HPO functioning in wealthier populations. Contrary to the presumption that humans have low fecundity and an inefficient reproductive system, both theory and present evidence suggest that we may actually have very high fecundity and a reproductive system that has evolved to be flexible, ruthlessly efficient and, most importantly, strategic. Yrbk Phys Anthropol 52:95,136, 2009. © 2009 Wiley-Liss, Inc. [source] Seasonal monogamy and multiple paternity in a wild population of a territorial reptile (tuatara)BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 1 2009JENNIFER A. MOORE Investigating the mating system of a population provides insight into the evolution of reproductive patterns, and can inform conservation management of threatened or endangered species. Combining behavioural and genetic data is necessary to fully understand the mating system and factors affecting male reproductive success, yet behavioural data are often difficult to collect for threatened species. In the present study, we use behavioural data and paternity analyses to characterize the mating system of a high density population of a long-lived, ancient reptile (tuatara, Sphenodon punctatus). We further investigate the phenotypic traits (including body size, body condition, tail length, and ectoparasite load) that affect male reproductive success. Our behavioural data reflect a seasonally monogamous system with low levels of polyandry and polygyny that are consistent with male mate guarding. Male reproduction is highly skewed (only 25,30% of males are successful), and body size is the primary predictor of male reproductive success. Based on the genetic data, multiple paternity was found in only 8% of clutches, and the results of the paternity analyses showed monandrous clutches from socially polyandrous females. Our behavioural and genetic results revealed complexities in female mating patterns that support the potential for cryptic female choice or sperm competition. This warrants further experimental investigation into the mechanisms underlying reptile fertilization and the disparities between social and genetic polyandry in wild populations. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 98, 161,170. [source] Life history evolution in a globally invading tephritid: patterns of survival and reproduction in medflies from six world regionsBIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 1 2009ALEXANDROS D. DIAMANTIDIS Comparisons among populations from different localities represent an important tool in the study of evolution. Medflies have colonized many temperate and tropical areas all over the world during the last few centuries. In a common garden environment, we examined whether medfly populations obtained from six global regions [Africa (Kenya), Pacific (Hawaii), Central America (Guatemala), South America (Brazil), Extra-Mediterranean (Portugal) and Mediterranean (Greece)] have evolved different survival and reproductive schedules. Whereas females were either short-lived [life expectancy at eclosion (e0) 48,58 days; Kenya, Hawaii and Guatemala] or long-lived (e0 72,76 days; Greece, Portugal and Brazil], males with one exception (Guatemala) were generally long-lived (e0 106,122 days). Although males universally outlived females in all populations, the longevity gender gap was highly variable (20,58 days). Lifetime fecundity rates were similar among populations. However, large differences were observed in their age-specific reproductive patterns. Short-lived populations mature at earlier ages and allocate more of their resources to reproduction early in life compared with long-lived ones. In all populations, females experienced a post-reproductive lifespan, with this segment being significantly longer in Kenyan flies. Therefore, it seems plausible that medfly populations, inhabiting ecologically diverse habitats, have evolved different life history strategies to cope with local environmental conditions. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 97, 106,117. [source] FEMININITY AND ITS UNCONSCIOUS ,SHADOWS': GENDER AND GENERATIVE IDENTITY IN THE AGE OF BIOTECHNOLOGYBRITISH JOURNAL OF PSYCHOTHERAPY, Issue 4 2007Joan Raphael-Leff abstract This paper locates contemporary conceptualizations of ,femininity' in the context of current sociocultural changes. It is argued that today's biotechnological opportunities have immense significance for both psychic interiority and the lived experience of gender, in that they invalidate ,eternal' limitations of sex, procreation and embodiment. An explanatory concept, generative identity, is postulated, to account psychologically for the increasing diversity of reproductive patterns. This concept is proposed as a fourth constituent of gender, alongside the reformulated constituents of embodiment, representation and desire. Derived from this is a further concept of generative agency, the expression of the psychic construction of the self as potential pro-creator, shaped in childhood by the negotiation of reproductive restrictions of sex, generation, genesis and generativity, and the ,genitive' issues of arbitrariness, finitude and irreversibility of time. Disturbances in generative identity manifest as unconscious ,shadows' expressed as inhibitions to creative agency, compulsively driven preoccupations with the lived sexed body, and/or concrete enactments which may utilize biotechnological innovations to actualize unconscious fantasies in reality. [source] | ||||||||||||||||||||||