Studies on the relationships and evolution of supraspecific taxa utilizing developmental data. 1. Stipa lemmonii (Gramineae)

1972 ◽  
Vol 50 (11) ◽  
pp. 2327-2352 ◽  
Author(s):  
Jack Maze ◽  
Lesley R. Bohm ◽  
Charles E. Beil
Keyword(s):  
Individual Differences ◽  
Pollen Tube ◽  
Early Development ◽  
Apical Meristem ◽  
Embryo Sac ◽  
Complex Structures ◽  
Plant Structure ◽  
Polygonum Type ◽  
The Individual ◽  
Developmental Features

This is a study of floret development and embryology of Stipa lemmonii (Vasey) Scribn. as a means of assessing its relationships and evolution. There is an advantage to using developmental data for it allows one to break complex structures down into developmental units. These developmental units can be compared and thus more characters can be analyzed. The lemma, palea, ventral lodicule, and carpel of S. lemmonii are leaf-like (sensu Sattler 1966, 1967) in initiation and early development. The stamens are stem-like and the ovule develops from the floret apical meristem. The ovule is interpreted as being cauline. The ovule is hemianatropous and pseudocrassinucellate. The inner integument delimits the micropyle. The integuments are ephemeral except for the inner layer of the inner integument. Embryo sac development is Polygonum type. Both synergids undergo change before entry of the pollen tube and the pollen tube appears to empty into the larger synergid. The antipodals are proliferated. The endosperm is at first free nuclear. Developmental features of S. lemmonii were compared with developmental features of S. tortilis, Oryzopsis miliacea, and S. hendersonii. The last is a species which hybridizes with S. lemmonii. Thirty-five characters were abstracted from the developmental data and were analyzed statistically. The results indicated that S. lemmonii and S. hendersonii are most closely related, and that these two plus S. tortilis form a group distinct from O. miliacea. The individual differences between taxa show gradation in the degree of difference. This is taken to indicate that the evolution of differences, and the evolution of taxa, is the result of the accumulation of many minor differences. Developmentally, plants are very simple, especially as compared with higher animals. Because of this, it is difficult to make generalizations about the "basic nature" of a plant structure using developmental data. Flowers seem best interpreted as functional units. This allows one to accept the concept that flowers in general are polyphyletic, a concept that is indicated by objective analysis of the data.

Embryo sac and early ovule development in Oryzopsis miliacea and Stipa tortilis

1970 ◽  
Vol 48 (1) ◽  
pp. 27-41 ◽  
Author(s):  
Jack Maze ◽  
Lesly R. Bohm ◽  
Lyle E. Mehlenbacher Jr.
Keyword(s):  
Cell Division ◽  
Pollen Tube ◽  
Nuclear Division ◽  
Outer Integument ◽  
Embryo Sac ◽  
Ovule Development ◽  
Polygonum Type ◽  
Embryo Sac Development

The ovules of Stipa tortilis and Oryzopsis miliacea are hemianatropous, bitegmetic, and pseudocrassinucellate (sensu Davis 1966). The hemianatropous shape of the ovule is the result of characteristic patterns of cell division and enlargement in the chalazal area and areas alongside the embryo sac. Embryo sac development in both is Polygonum-type and both have proliferating antipodals. Endosperm is nuclear, although in O. miliacea it is atypical in that nuclear division is synchronous within one portion of the embryo sac, e.g. micropylar, but not synchronous between different portions of the embryo sac, e.g., micropylar and chalazal. Differences in ovule initiation, persistence of the outer integument, fate of the inner integument, nature of the nucellus, shape of the embryo sac, nature of the synergids, cytoplasm of the egg, polar nuclei, and endosperm exist between these two taxa. Both synergids of O. miliacea undergo changes before fertilization and one degenerates before fertilization. The pollen tube enters the embryo sac at the base of the persistent synergid. There is presently insufficient embryological data to permit meaningful speculation on relationships between Stipa and Oryzopsis. Embryologically, Stipa and Oryzopsis are festucoid grasses, as much other evidence indicates. Embryo sac development in the Gramineae is more similar to that of the Restionaceae than to that of the Cyperaceae. This is in contradiction to recent speculations on the relationships of the Gramineae.

scholarly journals Desarrollo del gametofito femenino de Tagetes patula (Asteraceae)

2017 ◽  
pp. 5
Author(s):  
Marcelina García-Aguilar ◽  
E. Mark Engleman ◽  
Eulogio Pimienta-Barrios
Keyword(s):  
Seed Development ◽  
Early Development ◽  
Mother Cell ◽  
Megaspore Mother Cell ◽  
Embryo Sac ◽  
Tagetes Patula ◽  
Polygonum Type ◽  
Chalazal Megaspore ◽  
The Family ◽  
Apomictic Reproduction

The genus Tagetes reproduces sexually by seed, but recent morphological and hybridization studies in Tagetes patula suggest an apomictic type of reproduction (seed development without fertilization). In order to determine the sexual or apomictic origen of the embryo, we have studied megasporogenesis, megagametogenesis and the early development of the embryo. Tagetes patula L. has a typical ovule for the family Asteraceae: anatropous, unitegmic, tenuinucellate and with basal placentation. A single hypodermal archesporial cell develops directly as the megaspore mother cell. Megaspogenesis is normal and embryo sac develops from the chalazal megaspore. The embryo sac is of the Polygonum type. Female ray flowers show irregularities in megagametophyte development such as formation of more than eight nuclei, inverted polarity and incomplete differentiation of the megagametophyte cells in mature flowers. These irregularities do not necessarily prove apomictic reproduction in Tagetes patula.

Individual differences, social attention, and the history of the social motivation hypotheses of autism

2019 ◽  
Vol 42 ◽  
Author(s):  
Peter C. Mundy
Keyword(s):  
Individual Differences ◽  
Early Development ◽  
Emotional Development ◽  
Social Motivation ◽  
Social Attention ◽  
Social Emotional Development ◽  
Social Emotional ◽  
Precise Understanding ◽  
The Social ◽  
History Of

Abstract The stereotype of people with autism as unresponsive or uninterested in other people was prominent in the 1980s. However, this view of autism has steadily given way to recognition of important individual differences in the social-emotional development of affected people and a more precise understanding of the possible role social motivation has in their early development.

Directive Guidance as a Cultural Practice for Learning by Chinese-Heritage Babies

2021 ◽  
pp. 1-18
Author(s):  
Yu Zhang ◽  
Su-hua Wang ◽  
Shinchieh Duh
Keyword(s):  
Empirical Study ◽  
Early Development ◽  
Filial Piety ◽  
Theoretical Framework ◽  
Cultural Practice ◽  
European American ◽  
Individual Level ◽  
Children’S Learning ◽  
The Usa ◽  
The Individual

We provide a framework of analysis for Chinese ways of learning that extends beyond the individual level. The theoretical framework focuses on Confucian principles of <i>xiào</i> (孝, filial piety), <i>guăn</i> (管, to govern), and <i>dào dé guān</i> (道德觀, virtues), which leads us to argue that directive guidance as a cultural practice nourishes Chinese-heritage children’s learning as early as in infancy. To illustrate how directive guidance occurs in action for infants, we present an empirical study that examined the interaction of mother-infant dyads in Taipei, Taiwan, when they played with a challenging toy. The dyads co-enacted directive guidance more frequently than their European-American counterparts in the USA – through hand holding, intervening, and collaboration – while infants actively participate in the practice. We discuss the early development of strengths for learning that is fostered through culturally meaningful practices recurrent in parent-infant interaction.

Individual Uniqueness in the Neonatal Functional Connectome

2021 ◽  
Author(s):  
Qiushi Wang ◽  
Yuehua Xu ◽  
Tengda Zhao ◽  
Zhilei Xu ◽  
Yong He ◽  
...  
Keyword(s):  
Individual Differences ◽  
Individual Identification ◽  
Imaging Data ◽  
Functional Connectome ◽  
Middle Range ◽  
Human Connectome Project ◽  
The Individual ◽  
And Behavior ◽  
Identification Analysis ◽  
The Brain

Abstract The functional connectome is highly distinctive in adults and adolescents, underlying individual differences in cognition and behavior. However, it remains unknown whether the individual uniqueness of the functional connectome is present in neonates, who are far from mature. Here, we utilized the multiband resting-state functional magnetic resonance imaging data of 40 healthy neonates from the Developing Human Connectome Project and a split-half analysis approach to characterize the uniqueness of the functional connectome in the neonatal brain. Through functional connectome-based individual identification analysis, we found that all the neonates were correctly identified, with the most discriminative regions predominantly confined to the higher-order cortices (e.g., prefrontal and parietal regions). The connectivities with the highest contributions to individual uniqueness were primarily located between different functional systems, and the short- (0–30 mm) and middle-range (30–60 mm) connectivities were more distinctive than the long-range (&gt;60 mm) connectivities. Interestingly, we found that functional data with a scanning length longer than 3.5 min were able to capture the individual uniqueness in the functional connectome. Our results highlight that individual uniqueness is present in the functional connectome of neonates and provide insights into the brain mechanisms underlying individual differences in cognition and behavior later in life.

Predictors of Positive Psychological Capital: An Attempt Among the Teacher Communities in Rural Jharkhand, India

2021 ◽  
pp. 0258042X2199101
Author(s):  
Mukti Clarence ◽  
Viju P. D. ◽  
Lalatendu Kesari Jena ◽  
Tony Sam George
Keyword(s):  
Individual Differences ◽  
Organizational Support ◽  
Psychological Capital ◽  
Contextual Factors ◽  
Meaningful Work ◽  
Equation Modeling ◽  
School Teachers ◽  
Positive Psychological Capital ◽  
The Individual ◽  
The Impact

In the recent times, researchers have shown an increased interest in positive psychological capital (PsyCap). However, it is acknowledged that due to the limited number of studies conducted on the antecedents of psychological capital, there is a lack of sufficient data for conclusively proving the antecedents of PsyCap. Consequently, this article aims to explore the potential antecedents of PsyCap as a reliable source of data in the context of rural school teachers. The focus is to investigate both the individual differences and the contextual factors as desirable variables that constitute PsyCap among the school teachers of rural Jharkhand, India. Samples of 1,120 respondents from different rural schools were collected and analysed with Structural Equation Modeling (AMOS 20.0). The findings of the study explained that both the individual differences ( proactive personality and emotional intelligence) and the contextual factors ( perceived organizational support, servant leadership and meaningful work) have a positive relationship with PsyCap. The impact of PsyCap on teacher performance can form the basis for further research on the subject. JEL Codes: M12, M53

scholarly journals Paving the Way for Fertilization: The Role of the Transmitting Tract

2021 ◽  
Vol 22 (5) ◽  
pp. 2603
Author(s):  
Ana Marta Pereira ◽  
Diana Moreira ◽  
Sílvia Coimbra ◽  
Simona Masiero
Keyword(s):  
Pollen Tube ◽  
Pollen Tube Growth ◽  
Current Knowledge ◽  
Embryo Sac ◽  
Tube Growth ◽  
Signaling Cascades ◽  
Secretory Cells ◽  
Transmitting Tract ◽  
Specialized Tissue

Angiosperm reproduction relies on the precise growth of the pollen tube through different pistil tissues carrying two sperm cells into the ovules’ embryo sac, where they fuse with the egg and the central cell to accomplish double fertilization and ultimately initiate seed development. A network of intrinsic and tightly regulated communication and signaling cascades, which mediate continuous interactions between the pollen tube and the sporophytic and gametophytic female tissues, ensures the fast and meticulous growth of pollen tubes along the pistil, until it reaches the ovule embryo sac. Most of the pollen tube growth occurs in a specialized tissue—the transmitting tract—connecting the stigma, the style, and the ovary. This tissue is composed of highly secretory cells responsible for producing an extensive extracellular matrix. This multifaceted matrix is proposed to support and provide nutrition and adhesion for pollen tube growth and guidance. Insights pertaining to the mechanisms that underlie these processes remain sparse due to the difficulty of accessing and manipulating the female sporophytic tissues enclosed in the pistil. Here, we summarize the current knowledge on this key step of reproduction in flowering plants with special emphasis on the female transmitting tract tissue.

scholarly journals Individual Differences in the Vocal Communication of Malayan Tapirs (Tapirus indicus) Considering Familiarity and Relatedness

Animals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 1026
Author(s):  
Robin Walb ◽  
Lorenzo von Fersen ◽  
Theo Meijer ◽  
Kurt Hammerschmidt
Keyword(s):  
Individual Differences ◽  
Vocal Communication ◽  
Social Role ◽  
Animal Communication ◽  
Solitary Living ◽  
Low Visibility ◽  
Living Species ◽  
The Individual ◽  
Tapirus Indicus

Studies in animal communication have shown that many species have individual distinct calls. These individual distinct vocalizations can play an important role in animal communication because they can carry important information about the age, sex, personality, or social role of the signaler. Although we have good knowledge regarding the importance of individual vocalization in social living mammals, it is less clear to what extent solitary living mammals possess individual distinct vocalizations. We recorded and analyzed the vocalizations of 14 captive adult Malayan tapirs (Tapirus indicus) (six females and eight males) to answer this question. We investigated whether familiarity or relatedness had an influence on call similarity. In addition to sex-related differences, we found significant differences between all subjects, comparable to the individual differences found in highly social living species. Surprisingly, kinship appeared to have no influence on call similarity, whereas familiar subjects exhibited significantly higher similarity in their harmonic calls compared to unfamiliar or related subjects. The results support the view that solitary animals could have individual distinct calls, like highly social animals. Therefore, it is likely that non-social factors, like low visibility, could have an influence on call individuality. The increasing knowledge of their behavior will help to protect this endangered species.

Reproductive development in two species of Darwinia Rudge (Myrtaceae)

1969 ◽  
Vol 17 (2) ◽  
pp. 215 ◽  
Author(s):  
N Prakash
Keyword(s):  
Embryo Sac ◽  
Pollen Grains ◽  
Reproductive Development ◽  
Outer Zone ◽  
Mature Embryo ◽  
Globular Embryo ◽  
Primary Endosperm Nucleus ◽  
Oil Glands ◽  
Polygonum Type ◽  
History Of

In Darwinia the floral parts are differentiated in a "calyx-orolla-gynoeciumandroecium" sequence. In individual buds stages of microsporogenesis markedly precede corresponding stages of megasporogenesis. The anther is tetrasporangiate with all sporangia lying in one plane. The secretory tapetum is one- to three-layered within the same microsporangium and a large number of Ubisch bodies are formed. The anthers dehisce by minute lateral pores and an ingenious mechanism helps disperse the twocelled pollen grains. A basal placenta in the single loculus of the ovary bears four ovules in D. micropetala and two in D. fascicularis. In both species, however, only one ovule is functional after fertilization. The fully grown ovules are anatropous, crassinucellar, and bitegmic; the inner integument forms the micropyle. The parietal tissue is most massive at the completion of megasporogenesis but is progressively destroyed later. The embryo sac follows the Polygonum type of developnlent and when mature is five-nucleate, the three antipodals being ephemeral. Following fertilization, the primary endosperm nucleus divides before the zygote. Subsequent nuclear divisions in the endosperm mother cell are synchronous and lead to a free-nuclear endosperm which becomes secondarily cellular, starting from the micropylar end at the time the globular embryo assumes an elongated shape. Embryogeny is irregular and the mature embryo is straight with a massive radicle and a hypocotyl which terminates in two barely recognizable cotyledons. Sometimes the minute cotyledons are borne on a narrow neck-like extension of the hypocotyl. A suspensor is absent. Both integuments are represented in the seed coat and only the outer layer of the outer and the inner layer of the inner integuments, with their thick-walled tanniniferous cells, remain in the fully grown seed. The ovary wall is demarcated into an outer zone containing oil glands surrounded by cells containing a tannin-like substance and an inner zone of spongy parenchyma. In the fruit this spongy zone breaks down completely but the outer zone is retained. The two species of Darwinia, while closely resembling each other in their embryology, differ significantly from other Myrtaceae. However, no taxonomic conclusions are drawn at this stage, pending enquiry into the life history of other members of the tribe Chamaelaucieae.

Embryological studies in the compositae, I. Sporogenesis, Gametogenesis, and Embryogeny in Cotula australis (Less.) Hook. F

1962 ◽  
Vol 10 (1) ◽  
pp. 1 ◽  
Author(s):  
GL Davis
Keyword(s):  
Mother Cell ◽  
Megaspore Mother Cell ◽  
Embryo Sac ◽  
Subsequent Development ◽  
Pollen Grains ◽  
Archesporial Cell ◽  
Polygonum Type ◽  
Wall Formation ◽  
Chalazal Megaspore

Cotula australis has a discoid heterogamous capitulum in which the outermost three whorls of florets are female and naked. The bisexual disk florets are fully fertile and have a four-lobed corolla with four shortly epipetalous stamens. The anthers contain only two microsporangia. Wall formation and microsporogenesis are described and the pollen grains are shed at the three-celled condition. The ovule is teguinucellate and the hypodermal archesporial cell develops directly as the megaspore mother cell. Megasporogenesis is normal and the monosporio embryo sac develops from the chalazal megaspore. Breakdown of the nucellar epidermis takes place when the embryo sac is binucleate and its subsequent development follows the Polygonum type. The synergids extend deeply into the micropyle and one persists until late in embryogeny as a haustorium. The development of the embryo is of the Asterad type, and the endosperm is cellular. C. coronopifolia agrees with C. australis in the presence of only two microsporangia in each anther and the development of a synergid haustorium.

Sign in / Sign up

Export Citation Format

Share Document