THE BISEXUAL AND AGAMIC GENERATIONS OF BESBICUS MIRABILIS (HYMENOPTERA: CYNIPIDAE), AND THEIR ASSOCIATE INSECTS

1967 ◽  
Vol 99 (2) ◽  
pp. 187-196 ◽  
Author(s):  
David Evans
Keyword(s):  
Life History ◽  
Life Histories ◽  
First Record ◽  
Alternation Of Generations

AbstractAlternation of generations, or heterogony, wherein progeny resemble their grandparents but not their parents, is a little-known aspect of some cynipid life histories. This study represents the first record of its occurrence within the genus Besbicus, until now recognized solely from agamic females. The bisexual generation described herein has not been described previously. The literature on B. mirabilis (Kinsey) is reviewed briefly and some of the difficulties of cynipid study are assessed. The life history and ecology of both generations is presented and the immediate insect associates are discussed.

XVII.—Studies in the Ectocarpaceæ. I. The Life-History and Cytology of Pylaiella litoralis, Kjellm

1924 ◽  
Vol 53 (2) ◽  
pp. 343-360 ◽  
Author(s):  
Margery Knight
Keyword(s):  
Life History ◽  
Characteristic Feature ◽  
Life Histories ◽  
Marine Algae ◽  
Land Plants ◽  
Terrestrial Plants ◽  
Recent Suggestion ◽  
Alternation Of Generations

During the last few years attention has been focussed somewhat sharply upon the Marine Algæ, partly on account of the recently investigated life-histories of some of the larger Phæophyceæ, and partly because of a recent suggestion that the Marine Algæ may represent the stock from which all higher land-plants have originated. Interest has naturally centred on the problem of the origin of an alternation of generations among the seaweeds, comparable to that which has become a characteristic feature in the life-histories of higher terrestrial plants.

scholarly journals III. On apogamy and the development of sporangia upon fren prothalli

1898 ◽  
Vol 190 ◽  
pp. 187-238 ◽  
Keyword(s):  
Life History ◽  
Life Histories ◽  
Asexual Generation ◽  
First Case ◽  
History Of ◽  
The Subject ◽  
True Relation ◽  
The One ◽  
Vergleichende Untersuchungen ◽  
Alternation Of Generations

The two chief modifications of the normal course of the life-history of a fern, apogamy and apospory, are of interest in themselves, but have acquired a more extended importance from the possibility that their occurrence may aid in indicating the true relation between the sexual and spore-bearing generations, and so throw light on the nature of “alternation of generations” in archegoniate plants. This aspect has been recognised since the discovery of the phenomena, and will be best appreciated by tracing the progress of opinion on the nature of alternation from the time of Hofmeister to the present day. Only the more important contributions bearing on the subject can be mentioned in this place. With the publication of the ‘Vergleichende Untersuchungen’ (1851), the fact of the regular alternation of a sexual with an asexual generation in the life-history of Bryophyta, Pteridophyta, and Gymnosperms was established. Hofmeister subse­ quently extended the observation to Angiosperms. In the work mentioned, and in the ‘Higher Cryptogamia,’ published some ten years later, no views as to the nature of alternation of generations are discussed. With the extension of accurate know­ledge of the life-histories of Thallophytes, the attempt was made to compare the different individuals of the same species of Alga and Fungi with the sexual and asexual generations of archegoniate plants. Two main views of the nature of alter­nation in the latter were put forward. On the one hand, Celakovsky regarded alternation of generations in the Archegoniatse and a few Thallophyta as essentially different from that found in the majority of the latter group. He distinguished the two types as antithetic and homologous alternation respectively. Pringsheim however, held that the sexual and spore-bearing generations were homologous with one another, alike in Thallophyta and Archegoniatse. In support of this view he relied upon the instances of apospory which he had experimentally induced in Mosses, together with the occurrence of apogamy in Ferns, the first case of which had been discovered by Farlow a few years before. He also compared the life-histories of a number of Thallophytes witli one another and with that of the Moss, and showed how the reduction of the first neutral generation in some of the formerled to a condition of things not dissimilar to the relation existing between the moss sporogonium and the sexual plant. Additional cases of apogamy in Ferns were subsequently discovered by DeBary and the subject fully discussed. Subsequently Druery found the first instance of an aposporous fern, and this and other examples were investigated by Bower.

Hormones and Behavior

2019 ◽  
pp. 11-26
Author(s):  
Maren N. Vitousek ◽  
Laura A. Schoenle
Keyword(s):  
Life History ◽  
Life Histories ◽  
Life History Traits ◽  
Developmental Plasticity ◽  
Endocrine System ◽  
Phenotypic Traits ◽  
Social Environments ◽  
Trade Offs ◽  
And Behavior

Hormones mediate the expression of life history traits—phenotypic traits that contribute to lifetime fitness (i.e., reproductive timing, growth rate, number and size of offspring). The endocrine system shapes phenotype by organizing tissues during developmental periods and by activating changes in behavior, physiology, and morphology in response to varying physical and social environments. Because hormones can simultaneously regulate many traits (hormonal pleiotropy), they are important mediators of life history trade-offs among growth, reproduction, and survival. This chapter reviews the role of hormones in shaping life histories with an emphasis on developmental plasticity and reversible flexibility in endocrine and life history traits. It also discusses the advantages of studying hormone–behavior interactions from an evolutionary perspective. Recent research in evolutionary endocrinology has provided insight into the heritability of endocrine traits, how selection on hormone systems may influence the evolution of life histories, and the role of hormonal pleiotropy in driving or constraining evolution.

scholarly journals Classical soloists’ life histories and the music conservatoire

2021 ◽  
pp. 025576142199115
Author(s):  
Tim Palmer ◽  
David Baker
Keyword(s):  
Higher Education ◽  
Life History ◽  
Life Histories ◽  
Qualitative Data ◽  
Classical Music ◽  
Loss Of Autonomy ◽  
Cultural Interest ◽  
Concert Pianist ◽  
Analytic Induction ◽  
Musical Excellence

This article explores the life histories of virtuoso classical music soloists with particular reference to conservatoire provision. Detailed life-history interviews were conducted with six virtuosi between May 2018 and January 2019. These participants were three singers, two cellists and a concert pianist. Resultant qualitative data were stored in an NVivo software database and understood through a process of analytic induction. Key findings spotlight the significance of Higher Education, a connection between broad creative and cultural interest and musical excellence, and a significant role for conservatoires in diversifying their training and easing transition into the career. The soloists also warned of dangers relating to controlling teachers, loss of autonomy and a need to convey their career realities to students.

Inadvertent Exemplars: Life History Portraits of Two Socially Just Principals

2012 ◽  
Vol 22 (1) ◽  
pp. 79-115 ◽  
Author(s):  
Martin Scanlan
Keyword(s):  
Social Justice ◽  
Life History ◽  
Elementary Schools ◽  
Middle Class ◽  
Life Histories ◽  
Public Elementary Schools ◽  
White Middle Class ◽  
English Speaking ◽  
Native English Speaking

This study creates life history portraits of two White middle-class native-English-speaking principals demonstrating commitments to social justice in their work in public elementary schools serving disproportionately high populations of students who are marginalized by poverty, race, and linguistic heritage. Through self-reported life histories of these principals, I create portraits that illustrate how these practitioners draw motivation, commitment, and sustenance in varied, complicated, and at times contradictory ways.

A comparative study of the life histories of Nematodirus battus and N. filicollis, nematode parasites of sheep

Parasitology ◽  
1959 ◽  
Vol 49 (3-4) ◽  
pp. 374-386 ◽  
Author(s):  
R. J. Thomas
Keyword(s):  
Life History ◽  
Intestinal Mucosa ◽  
Related Species ◽  
Life Histories ◽  
Basic Pattern ◽  
Culture Methods ◽  
Closely Related Species ◽  
Nematode Parasites ◽  
History Of ◽  
Comparative Description

1. The life history of N. battus is described, and a comparative description of the life history of N. filicollis is given.2. The life histories of these two species are compared with those of N. spathiger and N. helvetianus, two closely related species, and are shown to follow the same basic pattern, with minor variations in timing which appear to be specific in nature, and not related to differences in culture methods or host species.3. The pathogenesis of Nematodirus species is discussed and related to the migration of larvae into the intestinal mucosa during development.

III.—The Life-history and Cytology of Didymium nigripes Fr.

1932 ◽  
Vol 57 (1) ◽  
pp. 93-142 ◽  
Author(s):  
Elsie J. Cadman
Keyword(s):  
Life History ◽  
Life Histories ◽  
Important Research ◽  
Great Work ◽  
Animal Kingdom ◽  
History Of ◽  
Natural Groups

Since 1860, in which year De Bary published his great work Die Mycetozoen, the investigation of the life-history of members of the Mycetozoa has aroused a considerable amount of interest, and a great deal of important research has been carried out in this connection. The group of organisms is particularly interesting, because it lies on the borderline between plant and animal kingdoms, and it is very possible that a detailed investigation of several species of the Mycetozoa might be of considerable assistance in elucidating certain obscure points in the life-histories of higher members of both the great natural groups. The term “Mycetozoa,” which we owe to De Bary, will be used throughout in preference to the older term “Myxogastres” invented by Fries (32, p. 2), and that of “Myxomycetes” first employed by Link (32, p. 2). “Mycetozoon,” or “fungus-like animal,” is a very appropriate description of a member of the group, since during part of its life-history it exhibits distinctly animal-like characters, and the individuals move rapidly by means of flagella, whilst later, during the development of the sporangium, a plant-like form is assumed. The combination of plant and animal characters has given rise to much discussion as to the position of the Mycetozoa in plant or animal kingdom, and the group has been claimed by both zoologists and botanists.

Eggs of extinct dwarf island emus retained large size

2021 ◽  
Vol 17 (5) ◽  
pp. 20210012
Author(s):  
Julian P. Hume ◽  
Christian Robertson
Keyword(s):  
Detailed Analysis ◽  
Life Histories ◽  
First Record ◽  
Museum Specimens ◽  
Linear Measurements ◽  
Large Size ◽  
Dromaius Novaehollandiae

Islands off southern Australia once harboured three subspecies of the mainland emu ( Dromaius novaehollandiae ), the smaller Tasmanian emu ( D. n. diemenensis ) and two dwarf emus, King Island emu ( D. n. minor ) and Kangaroo Island emu ( D. n. baudinianus ), which all became extinct rapidly after discovery by human settlers. Little was recorded about their life histories and only a few historical museum specimens exist, including a number of complete eggs from Tasmania and a unique egg from Kangaroo Island. Here, we present a detailed analysis of eggs of dwarf emus, including the first record of an almost complete specimen from King Island. Our results show that despite the reduction in size of all island emus, especially the King Island emu that averaged 44% smaller than mainland birds, the egg remained similar sized in linear measurements, but less in volume and mass, and seemingly had a slightly thinner eggshell. We provide possible reasons why these phenomena occurred.

A Primer of Life Histories

2021 ◽  
Author(s):  
Jeffrey A. Hutchings
Keyword(s):  
Life History ◽  
Life Histories ◽  
Life History Theory ◽  
Life History Traits ◽  
Reproductive Effort ◽  
Effective Means ◽  
Academic Experience ◽  
Sustainable Exploitation ◽  
Evolution Of Life ◽  
Opportune Time

Life histories describe how genotypes schedule their reproductive effort throughout life in response to factors that affect their survival and fecundity. Life histories are solutions that selection has produced to solve the problem of how to persist in a given environment. These solutions differ tremendously within and among species. Some organisms mature within months of attaining life, others within decades; some produce few, large offspring as opposed to numerous, small offspring; some reproduce many times throughout their lives while others die after reproducing just once. The exponential pace of life-history research provides an opportune time to engage and re-engage new generations of students and researchers on the fundamentals and applications of life-history theory. Chapters 1 through 4 describe the fundamentals of life-history theory. Chapters 5 through 8 focus on the evolution of life-history traits. Chapters 9 and 10 summarize how life-history theory and prediction has been applied within the contexts of conservation and sustainable exploitation. This primer offers an effective means of rendering the topic accessible to readers from a broad range of academic experience and research expertise.

scholarly journals The application of life history information to the conservation management of Chrysoritis butterflies (Lepidoptera: Lycaenidae) in South Africa

Koedoe ◽  
2004 ◽  
Vol 47 (1) ◽  
Author(s):  
R.F. Terblanche ◽  
H. Van Hamburg
Keyword(s):  
South Africa ◽  
Life History ◽  
Life Histories ◽  
Host Plants ◽  
Conservation Management ◽  
Aesthetic Value ◽  
Wing Patterns ◽  
In The Wild ◽  
History Of ◽  
Voucher Specimens

Due to their intricate life histories and the unique wing patterns and colouring the butterflies of the genus Chrysoritis are of significant conservation and aesthetic value. Thisoverview probes into practical examples of butterfly life history research applicable to environmental management of this relatively well-known invertebrate group in South Africa. Despite the pioneer work on life histories of Chrysoritis in the past, more should be done to understand the life history of the butterflies in the wild, especially their natural host plants and the behaviour of adults and larvae. A system of voucher specimens of host plants should be introduced in South Africa. Although various host plant species in nature are used by the members of Chrysoritis, including the Chrysoritis chrysaor group, the choice of these in nature by each species is significant for conservation management and in the case of Chrysoritis aureus perhaps even as a specific characteristic.A revision of the ant genus Crematogaster will benefit the conservation management of Chrysoritis species since some of these ant species may consist of a number of specieswith much more restricted distributions than previously thought. Rigorous quantified tudies of population dynamics of Chrysoritis butterflies are absent and the introductionof such studies will benefit conservation management of these localised butterflies extensively.

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