Journal articles: 'Modes of reproduction'

1

FISCHER, E. A. "Modes of Reproduction: Fish Reproduction." Science 227, no. 4693 (March 22, 1985): 1464–65. http://dx.doi.org/10.1126/science.227.4693.1464.

Full text

APA, Harvard, Vancouver, ISO, and other styles

2

Pichugin, Yuriy, Hye Jin Park, and Arne Traulsen. "Evolution of simple multicellular life cycles in dynamic environments." Journal of The Royal Society Interface 16, no. 154 (May 2019): 20190054. http://dx.doi.org/10.1098/rsif.2019.0054.

Full text

Abstract:

The mode of reproduction is a critical characteristic of any species, as it has a strong effect on its evolution. As any other trait, the reproduction mode is subject to natural selection and may adapt to the environment. When the environment varies over time, different reproduction modes could be optimal at different times. The natural response to a dynamic environment seems to be bet hedging, where multiple reproductive strategies are stochastically executed. Here, we develop a framework for the evolution of simple multicellular life cycles in a dynamic environment. We use a matrix population model of undifferentiated multicellular groups undergoing fragmentation and ask which mode maximizes the population growth rate. Counterintuitively, we find that natural selection in dynamic environments generally tends to promote deterministic, not stochastic, reproduction modes.

APA, Harvard, Vancouver, ISO, and other styles

3

Liedtke, H. Christoph, Hendrik Müller, Julian Hafner, Johannes Penner, David J. Gower, Tomáš Mazuch, Mark-Oliver Rödel, and Simon P. Loader. "Terrestrial reproduction as an adaptation to steep terrain in African toads." Proceedings of the Royal Society B: Biological Sciences 284, no. 1851 (March 29, 2017): 20162598. http://dx.doi.org/10.1098/rspb.2016.2598.

Full text

Abstract:

How evolutionary novelties evolve is a major question in evolutionary biology. It is widely accepted that changes in environmental conditions shift the position of selective optima, and advancements in phylogenetic comparative approaches allow the rigorous testing of such correlated transitions. A longstanding question in vertebrate biology has been the evolution of terrestrial life histories in amphibians and here, by investigating African bufonids, we test whether terrestrial modes of reproduction have evolved as adaptations to particular abiotic habitat parameters. We reconstruct and date the most complete species-level molecular phylogeny and estimate ancestral states for reproductive modes. By correlating continuous habitat measurements from remote sensing data and locality records with life-history transitions, we discover that terrestrial modes of reproduction, including viviparity evolved multiple times in this group, most often directly from fully aquatic modes. Terrestrial modes of reproduction are strongly correlated with steep terrain and low availability of accumulated water sources. Evolutionary transitions to terrestrial modes of reproduction occurred synchronously with or after transitions in habitat, and we, therefore, interpret terrestrial breeding as an adaptation to these abiotic conditions, rather than an exaptation that facilitated the colonization of montane habitats.

APA, Harvard, Vancouver, ISO, and other styles

4

Bunnell, F. L. "Reproduction of salal (Gaultheriashallon) under forest canopy." Canadian Journal of Forest Research 20, no. 1 (January 1, 1990): 91–100. http://dx.doi.org/10.1139/x90-013.

Full text

Abstract:

Sexual and vegetative reproduction of salal (Gaultheriashallon Pursh) was measured under forest canopies of different closure. Sexual reproduction occurred only at ≤33% closure; vegetative reproduction occurred under sparse and dense closure. Crown closure influenced sexual reproduction primarily through interception of radiation and associated reductions in salal vigour. Irradiance had a greater influence on the mode of reproduction than did shoot density, and allocation of total reproductive effort (sexual plus vegetative) was contrary to optimality models, but consistent with resource limitation. No shoot <5 years old flowered; shared costs of flowering indicated physiological integration among salal shoots. Vegetative reproduction was negatively associated with age (r2 = 0.95), and 85% of the space occupied after 9 years of growth was occupied during the first 3 years. Under canopy the spatial pattern of salal shoots was better adapted to maintain plant persistence than to colonize new areas. Implications of salal's rates and modes of reproduction to forest and wildlife management are noted.

APA, Harvard, Vancouver, ISO, and other styles

5

Haccou, Patsy, and Maria Victoria Schneider. "Modes of Reproduction and the Accumulation of Deleterious Mutations With Multiplicative Fitness Effects." Genetics 166, no. 2 (February 1, 2004): 1093–104. http://dx.doi.org/10.1093/genetics/166.2.1093.

Full text

Abstract:

Abstract Mutational load depends not only on the number and nature of mutations but also on the reproductive mode. Traditionally, only a few specific reproductive modes are considered in the search of explanations for the maintenance of sex. There are, however, many alternatives. Including these may give radically different conclusions. The theory on deterministic deleterious mutations states that in large populations segregation and recombination may lead to a lower load of deleterious mutations, provided that there are synergistic interactions. Empirical research suggests that effects of deleterious mutations are often multiplicative. Such situations have largely been ignored in the literature, since recombination and segregation have no effect on mutation load in the absence of epistasis. However, this is true only when clonal reproduction and sexual reproduction with equal male and female ploidy are considered. We consider several alternative reproductive modes that are all known to occur in insects: arrhenotoky, paternal genome elimination, apomictic thelytoky, and automictic thelytoky with different cytological mechanisms to restore diploidy. We give a method that is based on probability-generating functions, which provides analytical and numerical results on the distributions of deleterious mutations. Using this, we show that segregation and recombination do make a difference. Furthermore, we prove that a modified form of Haldane’s principle holds more generally for thelytokous reproduction. We discuss the implications of our results for evolutionary transitions between different reproductive modes in insects. Since the strength of Muller’s ratchet is reduced considerably for several forms of automictic thelytoky, many of our results are expected to be also valid for initially small populations.

APA, Harvard, Vancouver, ISO, and other styles

6

Prado, Cynthia, Masao Uetanabaro, and Célio Haddad. "Breeding activity patterns, reproductive modes, and habitat use by anurans (Amphibia) in a seasonal environment in the Pantanal, Brazil." Amphibia-Reptilia 26, no. 2 (2005): 211–21. http://dx.doi.org/10.1163/1568538054253375.

Full text

Abstract:

AbstractAnnual patterns of breeding activity, reproductive modes, and habitat use are described for a frog community in a seasonal environment, in the southern Pantanal, Mato Grosso do Sul, Brazil. Data were collected monthly between January 1995 and December 1998. A total of 24 species from four families; Bufonidae (3 species), Hylidae (10 species), Leptodactylidae (9 species), and Microhylidae (2 species) were registered. Three reproductive activity patterns are recognized among these species: continuous, explosive, and prolonged; 50% of the species were explosive breeders. Seasonal pattern of reproduction was verified for three analyzed years (1995-1997); most species reproduced during the rainy season (Nov-Jan). The reproduction was aseasonal in 1998; unexpected rains in the dry season lead to an unusual breeding activity. Five reproductive modes were noted — 62.5% of the species have the generalized aquatic mode, and 33.3% deposit eggs embedded in foam nests. Many species used the same sites for reproduction, although temporal partitioning and calling site segregation was observed. The occurrence of many species that exhibit explosive breeding early in the rainy season is common in seasonal and open environments with variable and unpredictable rainfall, as is the case in the Pantanal.

APA, Harvard, Vancouver, ISO, and other styles

7

Frantz, Adrien, Manuel Plantegenest, and Jean-Christophe Simon. "Temporal habitat variability and the maintenance of sex in host populations of the pea aphid." Proceedings of the Royal Society B: Biological Sciences 273, no. 1603 (August 15, 2006): 2887–91. http://dx.doi.org/10.1098/rspb.2006.3665.

Full text

Abstract:

The evolutionary maintenance of sex, despite competition from asexual reproduction, has long intrigued the evolutionary biologists owing to its numerous apparent short-term costs. In aphids, winter climate is expected to determine the maintenance of sexual lineages in the high latitude zones owing to their exclusive ability to produce frost-resistant eggs. However, diverse reproductive modes may coexist at a local scale where climatic influence is counteracted by microgeographical factors. In this study, we tested the influence of local habitat characteristics on regional coexistence of reproductive modes in the pea aphid, Acyrthosiphon pisum . In the laboratory, the induction of sexual morph production of many pea aphid genotypes from the local fields of annual (pea and faba bean) and perennial (alfalfa and red clover) crops in Western France indicated that A. pisum lineages from annual crops had a significantly higher investment in sexual reproduction than A. pisum lineages from the perennial hosts. We propose that temporal habitat variability exerts a selective pressure to maintain the sexual reproduction in A. pisum . The ecological and evolutionary consequences of the association between the mode of reproduction and the host population on gene flow restriction and on ecological specialization are discussed.

APA, Harvard, Vancouver, ISO, and other styles

8

Bourdieu, Pierre. "Stratégies de reproduction et modes de domination." Actes de la recherche en sciences sociales 105, no. 5 (December 1, 1994): 3–12. http://dx.doi.org/10.3917/arss.p1994.105n1.0003.

Full text

APA, Harvard, Vancouver, ISO, and other styles

9

Ghasarian, Christian. "L'anthropologie face aux nouveaux modes de reproduction." Journal des anthropologues 60, no. 1 (1995): 87–94. http://dx.doi.org/10.3406/jda.1995.1901.

Full text

APA, Harvard, Vancouver, ISO, and other styles

10

Bourdieu, Pierre. "Stratégies de reproduction et modes de domination." Actes de la recherche en sciences sociales 105, no. 1 (1994): 3–12. http://dx.doi.org/10.3406/arss.1994.3118.

Full text

APA, Harvard, Vancouver, ISO, and other styles

11

STREIT, ADRIAN. "Genetics: modes of reproduction and genetic analysis." Parasitology 144, no. 3 (March 22, 2016): 316–26. http://dx.doi.org/10.1017/s0031182016000342.

Full text

Abstract:

SUMMARYClassical and reverse genetics remain invaluable tools for the scientific investigation of model organisms. Genetic analysis of endoparasites is generally difficult because the sexual adults required for crossing and other manipulations are usually hidden within their host. Strongyloides spp. and Parastrongyloides spp. are notable exceptions to this and their free-living adults offer unique opportunities to manipulate these parasites experimentally. Here I review the modes of inheritance in the two generations of Strongyloides/Parastrongyloides and I discuss the opportunities and the limitations of the currently available methodology for the genetic analysis of these two genera.

APA, Harvard, Vancouver, ISO, and other styles

12

Gvoždík, Lumír. "Does reproduction influence temperature preferences in newts?" Canadian Journal of Zoology 83, no. 8 (August 1, 2005): 1038–44. http://dx.doi.org/10.1139/z05-096.

Full text

Abstract:

The influence of reproduction on body temperatures preferred in a laboratory thermal gradient has been studied mostly in ectotherms that are either viviparous or oviparous with prolonged egg retention. In this study I investigated whether reproduction influences temperature preferences in the Italian crested newt, Triturus carnifex (Laurenti, 1768), whose females do not carry embryos in utero (strict oviparity). I compared preferred temperatures and locomotor activity among reproductive females, non-reproductive females, and males in an aquatic thermal gradient (5–32.5 °C) over 24 h. Reproductive females preferred mean body temperatures 2.3–4.3 °C higher than those of non-reproductive females and males irrespective of activity level. Females regulated body temperature more precisely when reproductive than when non-reproductive as judged by the narrower range of preferred body temperatures. The study showed that the shift in temperature preferences of reproductive females occurs not only in species with advanced reproductive modes (i.e., viviparity and oviparity with egg retention), but also in a strictly oviparous mode.

APA, Harvard, Vancouver, ISO, and other styles

13

Hall, Rebecca Jane. "Reproduction and Resistance." Historical Materialism 24, no. 2 (June 30, 2016): 87–110. http://dx.doi.org/10.1163/1569206x-12341473.

Full text

Abstract:

In Northern Canada, Indigenous mixed economies persist alongside and in resistance to capital accumulation. The day-to-day sites and processes of colonial struggle, and, in particular, their gendered nature, are too often ignored. This piece takes an anti-colonial materialist approach to the multiple labours of Indigenous women in Canada, arguing that their social-reproductive labour is a primary site of struggle: a site of violent capitalist accumulation and persistent decolonising resistance. In making this argument, this piece draws on social-reproduction feminism, and anti-racist, Indigenous and anti-colonial feminism, asking what it means to take an anti-colonial approach to social-reproduction feminism. It presents an expanded conception of production that encompasses not just the dialectic of capitalist production and reproduction, but also non-capitalist, subsistence production. An anti-colonial approach to social-reproduction feminism challenges one to think through questions of non-capitalist labour and the way different forms of labour persist relationally, reproducing and resisting capitalist modes of production.

APA, Harvard, Vancouver, ISO, and other styles

14

Fyfe, Gordon. "Art and its Objects: William Ivins and the Reproduction of Art." Sociological Review 35, no. 1_suppl (May 1987): 65–98. http://dx.doi.org/10.1111/j.1467-954x.1987.tb00083.x.

Full text

Abstract:

This paper is a critique of the contribution of William Ivins's Prints and Visual Communication (1953) to an understanding of the meaning of fine art reproductions. Ivins showed that photographic reproduction was constructed in relation to, and displaced, older ways of reproducing art which were carried out by handicraft engravers. His analysis alerts us to the fact that ambiguity characterized art reproduction before photographs. Art reproductions, then, were interpretations in line based on conventional modes of representation – what Ivins calls a visual syntax. In this respect he enhances our understanding of the social construction of the artist. For Ivins the social history of reproduction seems to end with the camera. This completed an individuation of creativity ushered in with the Renaissance, but which was always qualified by the interfering visual syntax of craftsmen-interpreters. It is argued that the value of Ivins's account resides in its reconstruction of the relationship between handicraft engraving, fine art reproduction and aesthetic objects that have long since slipped from our consciousness.

APA, Harvard, Vancouver, ISO, and other styles

15

Liang, Yan, Olle Hints, Peng Tang, Chenyang Cai, Daniel Goldman, Jaak Nõlvak, Erik Tihelka, Ke Pang, Joseph Bernardo, and Wenhui Wang. "Fossilized reproductive modes reveal a protistan affinity of Chitinozoa." Geology 48, no. 12 (August 19, 2020): 1200–1204. http://dx.doi.org/10.1130/g47865.1.

Full text

Abstract:

Abstract Reproduction is a key aspect of evolution, but the process is rarely preserved in the fossil record. Organisms fortuitously preserved undergoing reproduction provide an exceptional window illuminating the biology of extinct taxa, especially those with unknown phylogenetic position. Here we report exceptional specimens of chitinozoans (enigmatic Paleozoic organic-walled microfossils) preserved as “test-in-test” morphology, which have previously been interpreted as teratological forms. Application of advanced imaging techniques on newly recovered and reexamined Ordovician materials enabled documentation of critical morphological details of the test’s inner ultrastructure for the first time. The results show that the newly observed spongy material and dendritic structure on or inside the chitinozoan test as well as the test wall itself are all made of clustered rounded spherical particles. Morphological details suggest that those specimens represent key stages of new asexual reproductive strategies, hitherto undescribed, which produce either one or several offspring at a time. This observation challenges the prevailing hypothesis that chitinozoans are eggs of cryptic extinct marine metazoans. Instead, it is more plausible that they represent a new isolated group of protists.

APA, Harvard, Vancouver, ISO, and other styles

16

Wang, Yan, Kean Chen, and Jian Xu. "Low Frequency Sound Field Reproduction within a Cylindrical Cavity Using Higher Order Ambisonics." Xibei Gongye Daxue Xuebao/Journal of Northwestern Polytechnical University 36, no. 4 (August 2018): 649–55. http://dx.doi.org/10.1051/jnwpu/20183640649.

Full text

Abstract:

Sound field reproduction of the aircraft and submarine within a cabin mock-up using a loudspeaker array is of great importance to the active noise control technology.The conventional method is to calculate the driving functions of the secondary sources by solving an acoustic inverse problem in a least square sense, which requires a large number of microphones and only the sound field near the microphone array can be reproduced accurately.In order to overcome these drawbacks, higher order ambisonics (HOA) method which is widely used in spatial sound field synthesis for a large room is introduced to reproduce a low frequency sound field within a cylindrical cavity.Due to the different sound propagation characteristics within the cavity compared with a free field and a diffuse field, the Green function spectrum in spherical harmonics domain which is modeled as a superposition of the acoustic modes and the reproduction formulas are deduced.Reproduction characteristics are investigated by numerical simulations.Results show that for a small, the Green function spectrum in spherical harmonics domain is mainly concentrated on low orders and contributed by the low order acoustic modes, with the increase of, high order components of the Green function arise and the contributions of high order acoustic modes increase.In the reproduction process, the high order components of the pressure spectrum over the sphere in harmonics domain will be greatly amplified by the reproduction filter.Finally, HOA method is compared with the acoustic inversion method in terms of the microphone array system, the impact factors on the reproductions and the reproduction accuracy, and validated through experiments.Results show that HOA can better reproduce the entire sound field within the cylindrical cavity and the reproduction accuracy is improved.

APA, Harvard, Vancouver, ISO, and other styles

17

Gavrilov-Zimin, Ilya A. "Chromosomal and reproductive features of some Oriental and Australasian scale insects (Homoptera, Coccinea)." Comparative Cytogenetics 14, no. 3 (July 20, 2020): 339–52. http://dx.doi.org/10.3897/compcytogen.v14i3.53367.

Full text

Abstract:

Fourteen species of scale insects from the families Margarodidae s.l., Pseudococcidae, Eriococcidae, and Coccidae were investigated for the first time in respect to karyotypes, genetic systems, modes of reproduction and general anatomy of the female reproductive system. One of the studied species, Steatococcus samaraius Morrison, 1927, showed hermaphroditic reproduction of the female-like specimens, the other species demonstrated bisexual reproduction with a peculiar “Lecanoid” heterochromatinization of the paternal set of chromosomes in male embryos or thelytocous parthenogenesis. Antonina parazonata Williams, 2004 and Saccharolecanium krugeri (Zehntner, 1897) are recorded here for the first time from Thailand, Antonina vietnamensis Williams, 2004 and Geococcus satellitum Williams, 2004 – for the first time from Laos.

APA, Harvard, Vancouver, ISO, and other styles

18

Wang, Xia, Yuming Chen, and Xinyu Song. "Global dynamics of a cholera model with age structures and multiple transmission modes." International Journal of Biomathematics 12, no. 05 (July 2019): 1950051. http://dx.doi.org/10.1142/s1793524519500517.

Full text

Abstract:

In this paper, we propose and analyze a cholera model. The model incorporates both direct transmission (person-to-person transmission) and indirect transmission (contaminated environment-to-person transmission: hyper-infectivity and lower-infectivity). Moreover, we employ general nonlinear incidences and introduce infection age of infectious individuals and biological ages of pathogens in the environment. After considering the well-posedness of the system, we study the existence and local stability of steady states, which is determined by the basic reproduction number. To establish the attractivity of the infection steady state, we also get the uniform persistence and existence of compact global attractors. The main result is a threshold dynamics obtained by applying the Fluctuation Lemma and the approach of Lyapunov functionals. When the basic reproduction number is less than one, the infection-free steady state is globally asymptotically stable while when the basic reproduction number is larger than one, the infection steady state attracts each solution with nonzero infection force at some time point. The effect of multiple transmission modes on the disease dynamics is also discussed.

APA, Harvard, Vancouver, ISO, and other styles

19

Schroder, H., M. Silverberg, B. Wendland, and G. Huerkamp. "Scanning Modes for Flicker-Free Colour TV-Reproduction." IEEE Transactions on Consumer Electronics CE-31, no. 4 (November 1985): 627–41. http://dx.doi.org/10.1109/tce.1985.289995.

Full text

APA, Harvard, Vancouver, ISO, and other styles

20

Bocharova, E. S., and I. A. Kozevich. "Modes of reproduction in sea anemones (Cnidaria, Anthozoa)." Biology Bulletin 38, no. 9 (December 2011): 849–60. http://dx.doi.org/10.1134/s1062359011090020.

Full text

APA, Harvard, Vancouver, ISO, and other styles

21

Thiemann, Martin, and August Ruthmann. "Alternative modes of asexual reproduction inTrichoplax adhaerens (Placozoa)." Zoomorphology 110, no. 3 (May 1991): 165–74. http://dx.doi.org/10.1007/bf01632872.

Full text

APA, Harvard, Vancouver, ISO, and other styles

22

Fautin, Daphne Gail. "Reproduction of Cnidaria." Canadian Journal of Zoology 80, no. 10 (October 1, 2002): 1735–54. http://dx.doi.org/10.1139/z02-133.

Full text

Abstract:

Empirical and experimental data on cnidarian reproduction show it to be more variable than had been thought, and many patterns that had previously been deduced hold up poorly or not at all in light of additional data. The border between sexual and asexual reproduction appears to be faint. This may be due to analytical tools being insufficiently powerful to distinguish between the two, but it may be that a distinction between sexual and asexual reproduction is not very important biologically to cnidarians. Given the variety of modes by which it is now evident that asexual reproduction occurs, its ecological and evolutionary implications have probably been underestimated. Appropriate analytical frameworks and strategies must be developed for these morphologically simple animals, in which sexual reproduction may not be paramount, that during one lifetime may pass though two or more phases differing radically in morphology and ecology, that may hybridize, that are potentially extremely long-lived, and that may transmit through both sexual and asexual reproduction mutations arising in somatic tissue. In cnidarians, perhaps more than in any other phylum, reproductive attributes have been used to define taxa, but they do so at a variety of levels and not necessarily in the way they have conventionally been considered. At the species level, in Scleractinia, in which these features have been most studied, taxa defined on the basis of morphology, sexual reproduction, and molecular characters may not coincide; there are insufficient data to determine if this is true throughout the phylum. At the class level, transverse fission occurs in members of all three major taxa but is rare outside Scyphozoa, the group of which it is considered characteristic (pending more research, its absence in Cubozoa should be ascribed to poor knowledge). Understanding the role of transverse fission in the ecology and reproductive biology of hydrozoans and anthozoans could shed light on scyphozoan evolutionary history, and elucidating its morphogenesis in all groups is essential to determining if it is homologous across the classes. Only by comparing aspects of reproduction among cnidarians of various taxa will idiosyncratically adaptive strategies be distinguished from reproductive characters that reflect evolution and so are phylogenetically informative.

APA, Harvard, Vancouver, ISO, and other styles

23

Miao, Hui, and Meiyan Jiao. "Spatiotemporal Dynamics of a Delayed Viral Infection Model with Two Modes of Transmission and Immune Impairment." Discrete Dynamics in Nature and Society 2022 (April 26, 2022): 1–19. http://dx.doi.org/10.1155/2022/9531450.

Full text

Abstract:

In this paper, the dynamical behaviors for a diffusive virus infection model with two general nonlinear incidence functions, CTL immune impairment and discrete delays, are investigated. Cell-to-cell transmission plays a more important role in virus spreading in addition to virus-to-cell infection. Nonnegativity and boundcedness properties of the solutions are proven to show the well-posedness of the model. Five reproduction numbers are calculated and verified to be thresholds determining the global properties of the virus model. A significant impact of cell-to-cell transmission is that they increase the basic reproduction number. If one neglects either the cell-to-cell transmission or virus-to-cell infection, the basic reproduction number of the model is underevaluated. Numerical simulations are carried out to illustrate the dynamical behavior of the model.

APA, Harvard, Vancouver, ISO, and other styles

24

Miao, Hui, and Meiyan Jiao. "Spatiotemporal Dynamics of a Delayed Viral Infection Model with Two Modes of Transmission and Immune Impairment." Discrete Dynamics in Nature and Society 2022 (April 26, 2022): 1–19. http://dx.doi.org/10.1155/2022/9531450.

Full text

Abstract:

In this paper, the dynamical behaviors for a diffusive virus infection model with two general nonlinear incidence functions, CTL immune impairment and discrete delays, are investigated. Cell-to-cell transmission plays a more important role in virus spreading in addition to virus-to-cell infection. Nonnegativity and boundcedness properties of the solutions are proven to show the well-posedness of the model. Five reproduction numbers are calculated and verified to be thresholds determining the global properties of the virus model. A significant impact of cell-to-cell transmission is that they increase the basic reproduction number. If one neglects either the cell-to-cell transmission or virus-to-cell infection, the basic reproduction number of the model is underevaluated. Numerical simulations are carried out to illustrate the dynamical behavior of the model.

APA, Harvard, Vancouver, ISO, and other styles

25

Taherti, Mourad, and Rachid Kaidi. "Reproductive performance and numerical productivity of Ouled Djllal ewes." Lebanese Science Journal 19, no. 1 (April 27, 2018): 47–58. http://dx.doi.org/10.22453/lsj-019.1.047-058.

Full text

Abstract:

In order to measure the reproductive performances and numerical productivity of Ouled Djellal ewes, and to determine the influence of non-geneticfactors onthese parameters, a database wasestablished, by monitoring 2710 ewes, belonging to 12 farms, representative of two dominant modes of reproduction in the Chlef region. Body condition scores (BCS) of groups ofewes put in reproduction were carried out to compare the performances under breedingconditions. Thestudy showed a fertility and prolificacy of 91.04% and 115.35% in the breeding mode of lambing per year in spring, against 59.35% and 103% in the traditionalsystem with lambingspread over the year (the ram is permanently present in the herd). The body condition and body reserves of the ewes varied according to the lambing season and the farmsmanagement (feed system). The interaction between the body condition of the ewes at mating and their reproduction performances was evident. Indeed, as BCS at mating increased, fertility, prolificityand productivity improved. The ewes with BCS at mating higher than or equalto3 produced the best performance, whereasthe ewes with BCS lower than 3, were less fertile, less prolific and less productive. On average the productivity of Ouled Djellal ewes was 105.03% and 61.10%, respectively,in the first and second mode of reproduction. The main sources of variation as well as their interactions, were highlighted in this study.

APA, Harvard, Vancouver, ISO, and other styles

26

Stewart, Paul. "Sexual and Aesthetic Reproduction in." Samuel Beckett Today / Aujourd'hui 22, no. 1 (October 1, 2010): 149–62. http://dx.doi.org/10.1163/18757405-022001011.

Full text

Abstract:

Malone's narratives are investigated through their relation to Schiller's and Schopenhauer's championing of aesthetic contemplation. Although Beckett follows Schopenhauer in his condemnation of the will-to-live, particularly as represented by procreation, it is argued that the narratives of Malone reveal an inability to create pure, disinterested, aesthetic objects. The paradigms of fictional creation adopted by Malone are infected by modes proper to sexual reproduction and therefore fail to release Malone from time and the will. It is argued that the reproductive motifs within demonstrate Beckett's subtle rejection of the aesthetic optimism of Schopenhauer and Schiller.

APA, Harvard, Vancouver, ISO, and other styles

27

Dinis, Marco, and Guillermo Velo-Antón. "How little do we know about the reproductive mode in the north African salamander, Salamandra algira? Pueriparity in divergent mitochondrial lineages of S. a. tingitana." Amphibia-Reptilia 38, no. 4 (2017): 540–46. http://dx.doi.org/10.1163/15685381-00003121.

Full text

Abstract:

Salamandra algirais one of the few species of vertebrates that displays intraspecific variation in reproductive strategies, making it a valuable study model in reproductive mode evolution. How pueriparity (viviparity) inS. algiraarose remains unclear mainly due to insufficient information on the distribution of both reproductive modes in the species. This note summarizes what is known about pueriparous reproduction inS. algiraand adds new data on the distribution and geographic limits of both reproductive strategies and mitochondrial lineages withinS. a. tingitanaacross the Western Rif in Morocco, with possible implications for our understanding of the ecological context of pueriparity. The occurrence of pueriparity in two mitochondrial sublineages suggests multiple events of pueriparity evolution inS. algira, or a model of mitochondrial capture through hybridization and introgression across the contact zone.

APA, Harvard, Vancouver, ISO, and other styles

28

Zhang, Li, Ping Ma, Lee-Man Chu, and Paul Pui-Hay But. "Three modes of asexual reproduction in the mossOctoblepharum albidum." Journal of Bryology 25, no. 3 (September 2003): 175–79. http://dx.doi.org/10.1179/037366803235001751.

Full text

APA, Harvard, Vancouver, ISO, and other styles

29

Goodrich, Peter. "Zenotypes: On the Modes of Reproduction of Critical Lawyers." Social & Legal Studies 11, no. 3 (September 2002): 425–43. http://dx.doi.org/10.1177/096466390201100310.

Full text

APA, Harvard, Vancouver, ISO, and other styles

30

ODEA, AARON, JEREMY B. C. JACKSON, PAUL D. TAYLOR, and FELIX RODRGUEZ. "MODES OF REPRODUCTION IN RECENT AND FOSSIL CUPULADRIID BRYOZOANS." Palaeontology 51, no. 4 (July 2008): 847–64. http://dx.doi.org/10.1111/j.1475-4983.2008.00790.x.

Full text

APA, Harvard, Vancouver, ISO, and other styles

31

Levites, E. V. "New classification of the reproduction modes in sugar beet." Sugar Tech 4, no. 1-2 (June 2002): 45–51. http://dx.doi.org/10.1007/bf02956879.

Full text

APA, Harvard, Vancouver, ISO, and other styles

32

Wang, Yongcui, Busso Carlos Alberto, Deming Jiang, Musa Ala, Xuehua Li, Quanlai Zhou, Jixiang Lin, Guohua Ren, and Lian Jia. "The role of sexual vs. asexual recruitment of <i>Artemisia wudanica</i> in transition zone habitats between inter-dune lowlands and active dunes in Inner Mongolia, China." Solid Earth 7, no. 2 (April 18, 2016): 621–29. http://dx.doi.org/10.5194/se-7-621-2016.

Full text

Abstract:

Abstract. Artemisia wudanica is an endemic, perennial, pioneering psammophyte species in the sand dune ecosystems of western Horqin Sand Land in northern China. However, no studies have addressed how sexual and asexual reproduction modes of A. wudanica perform at the transitional zones between active dune inter-dune lowlands and active dunes. In early spring, quadrats were randomly set up in the study area to monitor surviving seedling and/or ramet density and frequency coming from sexual/asexual reproduction of A. wudanica. Iron sticks were inserted near each quadrat to determine wind erosion intensity (WE). Additionally, soil samples were collected nearby each quadrat to test for soil moisture (SM), organic matter (OM) and pH. Surviving seedlings of A. wudanica showed an inverse response in comparison with ramets to SM, OM and WE. Soil moisture showed the most positive effect, and WE the negative effect, on surviving, sexual reproduction seedlings. Contrarily, WE had the most positive effect, and SM the negative effect, on asexual reproduction ramets. This suggests that increases in SM and decreases in WE should benefit recruitment of A. wudanica seedlings. On the contrary, ramets coming from asexual reproduction showed a different response to environmental factors in transition zone habitats. While SM was not a key constraint for the survival of seedlings, they showed a better, positive response to wind erosion environments. Overall, various study environmental parameters could be improved to foster A. wudanica invasion and settlement in the plant community through different reproductive modes, thereby promoting vegetation restoration and rehabilitation.

APA, Harvard, Vancouver, ISO, and other styles

33

Bogart, James P., and Lawrence E. Lichts. "Reproduction and the origin of polyploids in hybrid salamanders of the genus Ambystoma." Canadian Journal of Genetics and Cytology 28, no. 4 (August 1, 1986): 605–17. http://dx.doi.org/10.1139/g86-089.

Full text

Abstract:

Eggs and larvae produced by diploid, triploid, and tetraploid females collected from breeding ponds on Pelee Island in Lake Erie were studied to examine the reproductive mechanism. No instance of parthenogenesis was found as all examined females required sperm to produce viable progeny. Diploid females produced diploid and triploid larvae, triploid females produced triploid and tetraploid larvae, and tetraploid females produced triploid and tetraploid larvae. The majority of the eggs produced by hybrid females do not develop or do not complete embryogenesis. Electrophoretic examination of females and their offspring demonstrate that the male genome is being incorporated in reduced as well as unreduced eggs produced by all three ploidy classes of females. The elevation of ploidy among Pelee Island Ambystoma is attributed to sperm incorporation in unreduced eggs. Triploid as well as tetraploid individuals are constantly being produced. A critical examination of the literature on parthenogenetic or gynogenetic modes of reproduction in North American Ambystoma hybrids shows no conclusive evidence supporting these modes and it is suggested that the reproductive mechanism found among Pelee Island female hybrids may be more generally applied to other hybrid Ambystoma populations.Key words: Ambystoma, polyploids, hybrids, electrophoresis, reproduction.

APA, Harvard, Vancouver, ISO, and other styles

34

Allen, L., K. L. Sanders, and V. A. Thomson. "Molecular evidence for the first records of facultative parthenogenesis in elapid snakes." Royal Society Open Science 5, no. 2 (February 2018): 171901. http://dx.doi.org/10.1098/rsos.171901.

Full text

Abstract:

Parthenogenesis is a form of asexual reproduction by which embryos develop from unfertilized eggs. Parthenogenesis occurs in reptiles; however, it is not yet known to occur in the widespread elapid snakes (Elapidae), which include well-known taxa such as cobras, mambas, taipans and sea snakes. Here, we describe the production of viable parthenogens in two species of Australo-Papuan elapids with divergent reproductive modes: the oviparous coastal/Papuan taipan ( Oxyuranus scutellatus ) and the viviparous southern death adder ( Acanthophis antarcticus ). Analyses of nuclear SNP data excluded paternity for putative fathers and convincingly demonstrated asexual reproduction, thus representing the first evidence of facultative parthenogenesis in Elapidae. Our finding has broad implications for understanding the evolution of reproductive diversity in snakes, as well as managing the conservation of genetic diversity in wild and captive populations.

APA, Harvard, Vancouver, ISO, and other styles

35

MANSOURNIA, Mohammad Reza, Bingyun WU, Norihisa MATSUSHITA, and Taizo HOGETSU. "Genotypic analysis of the foliose lichen Parmotrema tinctorum using microsatellite markers: association of mycobiont and photobiont, and their reproductive modes." Lichenologist 44, no. 3 (March 29, 2012): 419–40. http://dx.doi.org/10.1017/s0024282911000909.

Full text

Abstract:

AbstractTo investigate the association between, and the reproductive modes of, mycobiont and photobiont in the lichen Parmotrema tinctorum, microsatellite markers (SSR markers) were developed for both bionts and genotypic analysis was performed for thalli in a Pinus thunbergii forest. In a within-thallus analysis, tissue pieces were sampled from many portions within each of five thalli. Within-thallus variation for both mycobiont and photobiont differed among the thalli investigated, suggesting that a single thallus can be derived from either a single mycobiont origin with or without occasional changes in the photobiont, or fusion of several independent thalli. In the within-tree analysis, thalli with the same genotypes were found on individual trees, suggesting the presence of short-distance isidium dispersal. In the within-stand analysis, genotypically similar photobionts tended to be associated with the same mycobiont genotype, suggesting the participation of local dispersal via isidia. The overall index of association (IA) for the mycobiont in the stand probably indicates the dominance of sexual reproduction, in contrast to that of the photobiont, where dominance of asexual reproduction is suggested. IA's of mycobiont and photobiont were also calculated for thalli collected from larger areas, where there is a signature for sexual reproduction for photobiont.

APA, Harvard, Vancouver, ISO, and other styles

36

Lee, Soo Chan, Min Ni, Wenjun Li, Cecelia Shertz, and Joseph Heitman. "The Evolution of Sex: a Perspective from the Fungal Kingdom." Microbiology and Molecular Biology Reviews 74, no. 2 (June 2010): 298–340. http://dx.doi.org/10.1128/mmbr.00005-10.

Full text

Abstract:

SUMMARY Sex is shrouded in mystery. Not only does it preferentially occur in the dark for both fungi and many animals, but evolutionary biologists continue to debate its benefits given costs in light of its pervasive nature. Experimental studies of the benefits and costs of sexual reproduction with fungi as model systems have begun to provide evidence that the balance between sexual and asexual reproduction shifts in response to selective pressures. Given their unique evolutionary history as opisthokonts, along with metazoans, fungi serve as exceptional models for the evolution of sex and sex-determining regions of the genome (the mating type locus) and for transitions that commonly occur between outcrossing/self-sterile and inbreeding/self-fertile modes of reproduction. We review here the state of the understanding of sex and its evolution in the fungal kingdom and also areas where the field has contributed and will continue to contribute to illuminating general principles and paradigms of sexual reproduction.

APA, Harvard, Vancouver, ISO, and other styles

37

Human, Maria Petronella, Irene Barnes, Maryke Craven, and Bridget Genevieve Crampton. "Lack of Population Structure and Mixed Reproduction Modes in Exserohilum turcicum from South Africa." Phytopathology® 106, no. 11 (November 2016): 1386–92. http://dx.doi.org/10.1094/phyto-12-15-0311-r.

Full text

Abstract:

Exserohilum turcicum is the causal agent of northern corn leaf blight, a destructive foliar disease of maize that results in yield losses worldwide. In South Africa, typical yield losses range from 15 to 30%. Previous studies found high haplotypic diversity with evidence for sexual recombination in E. turcicum populations from tropical climates such as Kenya. However, the population genetic structure and method of reproduction of E. turcicum in South Africa is unknown and, therefore, was investigated. Twelve polymorphic microsatellite markers were screened on 258 E. turcicum isolates from maize collected during 2012 and 2013 from three maize fields in South Africa. A multiplex polymerase chain reaction assay amplifying both mating type idiomorphs was applied to investigate the distribution of mating types. No distinct genetic clusters were observed. Shared haplotypes were identified between isolates separated by distances of up to 762 km, which provided evidence of migration. High haplotypic diversity indicated that sexual reproduction is occurring among E. turcicum isolates, although mating type ratios and linkage disequilibrium analyses did not support the hypothesis of random mating. The population genetic structure of E. turcicum in South Africa is likely due to the direct movement and spread of isolates undergoing a mixed reproductive lifecycle.

APA, Harvard, Vancouver, ISO, and other styles

38

Неверова, Г. П., and G. P. Neverova. "Dynamic Modes of Limited Structured Population under Age Specific Harvest." Mathematical Biology and Bioinformatics 12, no. 2 (October 9, 2017): 327–42. http://dx.doi.org/10.17537/2017.12.327.

Full text

Abstract:

The paper investigates influence of age specific harvest on the dynamics of populations with density dependent regulation of birth rate. We consider the population which by the end of each reproduction season, consists of two age groups: juveniles (immature individuals) and adults (participants of the reproduction process). A harvest rate growth of any age class is shown to give, as a rule, the dynamics stabilization. However, the system with harvesting demonstrates multimodality phenomenon as well as the population model without exploitation. The phenomenon means different dynamic modes are observed with the same values of the population parameters. As a result, some difficulties occur in predicting population dynamics, because harvest can lead to significant changes of population size due to shifting current population size from one attraction basin to another. To neutralize the oscillations emerged is necessary to change the current population size so that it falls into the attraction basin of the fixed point. The stability loss way of model with juvenile harvesting does not depend on the harvest rate value and is completely determined by the intensity of competitive relationships between the age classes. In the case of adult exploitation, a higher harvest rate can result in growing stationary population size. The changing the time of adult harvesting can lead to both the dynamics population stabilization and the occurrence of fluctuations. Exploitation before the reproduction season allows to have more yield than after reproduction season because mature age group size is higher. Conditions when the age specific harvest gives the maximum sustainable yield are considered.

APA, Harvard, Vancouver, ISO, and other styles

39

Wells, Robert V., and Alan Macfarlane. "Marriage and Love in England: Modes of Reproduction, 1300-1840." Journal of Marriage and the Family 48, no. 4 (November 1986): 891. http://dx.doi.org/10.2307/352587.

Full text

APA, Harvard, Vancouver, ISO, and other styles

40

O'Hara, Diana, and Alan MacFarlane. "Marriage and Love in England: Modes of Reproduction, 1300-1840." Economic History Review 40, no. 1 (February 1987): 113. http://dx.doi.org/10.2307/2596300.

Full text

APA, Harvard, Vancouver, ISO, and other styles

41

O'Malley, Patricia Trainor, and Alan Macfarlane. "Marriage and Love in England: Modes of Reproduction, 1300-1840." Journal of Interdisciplinary History 18, no. 3 (1988): 492. http://dx.doi.org/10.2307/203902.

Full text

APA, Harvard, Vancouver, ISO, and other styles

42

Fox, Vivian Carol, Alan MacFarlane, and Judith Schneid Lewis. "Marriage and Love in England: Modes of Reproduction, 1300-1840." American Historical Review 92, no. 4 (October 1987): 951. http://dx.doi.org/10.2307/1863992.

Full text

APA, Harvard, Vancouver, ISO, and other styles

43

Levine, David, and Alan MacFarlane. "Marriage and Love in England: Modes of Reproduction 1300-1840." Contemporary Sociology 15, no. 5 (September 1986): 748. http://dx.doi.org/10.2307/2071058.

Full text

APA, Harvard, Vancouver, ISO, and other styles

44

PEARSE, JOHN S., JAMES B. MCCLINTOCK, and ISIDRO BOSCH. "Reproduction of Antarctic Benthic Marine Invertebrates: Tempos, Modes, and Timing." American Zoologist 31, no. 1 (February 1991): 65–80. http://dx.doi.org/10.1093/icb/31.1.65.

Full text

APA, Harvard, Vancouver, ISO, and other styles

45

Hastrup, Kirsten, and Alan Macfarlane. "Marriage and Love in England: Modes of Reproduction 1300-1840." Man 22, no. 4 (December 1987): 760. http://dx.doi.org/10.2307/2803378.

Full text

APA, Harvard, Vancouver, ISO, and other styles

46

Tripp, Erin A., and James C. Lendemer. "Twenty-seven modes of reproduction in the obligate lichen symbiosis." Brittonia 70, no. 1 (December 12, 2017): 1–14. http://dx.doi.org/10.1007/s12228-017-9500-6.

Full text

APA, Harvard, Vancouver, ISO, and other styles

47

Sumner, Seirian, and Laurent Keller. "Social Evolution: Reincarnation, Free-Riding and Inexplicable Modes of Reproduction." Current Biology 18, no. 5 (March 2008): R206—R207. http://dx.doi.org/10.1016/j.cub.2008.01.004.

Full text

APA, Harvard, Vancouver, ISO, and other styles

48

Komdeur, Jan. "No evidence for adaptive suppression of joint laying by dominant female Seychelles warblers: an experimental study." Behaviour 142, no. 11-12 (2005): 1669–84. http://dx.doi.org/10.1163/156853905774831864.

Full text

Abstract:

AbstractSeveral theoretical frameworks exist for explaining variation in reproductive allocation between same-sex individuals living within social groups. To determine this adequately, we need to know which party is more able to manipulate reproduction of the other. Theoretical models often sidestep this problem by making the assumption that dominants either have complete or partial control of reproduction by subordinates. This study clearly indicates that in the cooperatively breeding Seychelles warbler (Acrocephalus sechellensis) this assumption is not met. Seychelles warblers occupy year-round territories of different quality (measured as amount of insect food available). Joint laying, in which the dominant and subordinate females lay eggs in the same nest, decreases the fitness of primary females on low-quality territories, but not on high-quality territories. This study found good experimental evidence that dominant females on low-quality territories have no modes to suppress or prevent subordinate females from joint laying: (i) The frequency of joint laying in multi-female groups is independent of territory quality; (ii) There is no aggression among females at the nest around the time of egg laying at either low- or high-quality territories; (iii) Dominant females do not remove the other female's egg or experimentally introduced eggs, before or after laying their own. (iv) Dominant females do not reject an experimentally introduced egg through nest desertion. Given the absence of reproductive control, increased attention to alternative models of reproductive partitioning in vertebrate societies is needed and a realistic model has to take into account interactions within the sexes.

APA, Harvard, Vancouver, ISO, and other styles

49

Hagedorn, Mary, and Virginia L. Carter. "Cryobiology: principles, species conservation and benefits for coral reefs." Reproduction, Fertility and Development 28, no. 8 (2016): 1049. http://dx.doi.org/10.1071/rd16082.

Full text

Abstract:

Coral reefs are some of the oldest, most diverse and valuable ecosystems on Earth because they can support one-quarter of all marine life in our oceans. Despite their importance, the world’s coral reefs continue to be degraded at unprecedented rates by local and global threats that are warming and creating a more acidic ocean. This paper explores the reproductive challenges of coral for ex situ conservation, using IVF and cryopreservation, and our practical biobanking methods. Coral present challenges for cryopreservation because their reproductive period is often limited to a few nights yearly, they are mostly hermaphrodites with diverse modes of reproduction, including asexual reproduction (i.e. fragmentation and parthenogenesis) and sexual reproduction (i.e. self- and cross-fertilisation) and they express physiological toxins that can inhibit cryopreservation. We have banked spermatozoa from 12 coral species using the same field-hardy methods and have created new coral with thawed spermatozoa. In addition, we describe the cryopreservation of coral symbionts, whose physiology only permits the highest success seasonally. As part of a multidisciplinary conservation strategy, these collections may provide a major hedge against extinction for corals facing the damaging effects of climate change and loss of genetic diversity, and promise to help offset threats to our reefs worldwide.

APA, Harvard, Vancouver, ISO, and other styles

50

Piippo, Sinikka. "On the asexual reproduction of Plagiochila pluma Steph." Bryophyte Diversity and Evolution 5, no. 1 (December 1, 1992): 7–10. http://dx.doi.org/10.11646/bde.5.1.4.

Full text

Abstract:

Four types of asexual reproduction in Plagiochila and the Plagiochilaceae are known: propagules, caducous leaves, gemmae and cladia. Plagiochila pluma Steph. has caducous leaves and teeth with regenerants. The terms for asexual reproduction modes in liverworts are briefly discussed and new definitions proposed.

APA, Harvard, Vancouver, ISO, and other styles

Journal articles on the topic 'Modes of reproduction'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles