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  • 1
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Ecology, Evolution, and Systematics 35 (2004), S. 55-87 
    ISSN: 1543-592X
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology
    Notes: Bird song provides an unusually impressive illustration of vertebrate behavioral diversification. Research on bird song evolution traditionally focuses on factors that enhance song diversity, such as cultural transmission and sexual selection. Recent advances in the study of proximate mechanisms of vocal behavior, however, provide opportunities for studying mechanistic constraints on song evolution. The main goal of this review is to examine, from both conceptual and empirical perspectives, how proximate mechanisms might temper patterns of song evolution. We provide an overview of the two "substrates" of song evolution, memes and vocal mechanisms. We argue that properties of vocal mechanisms (control, production, and ontogeny) constrain vocal potential and may thus limit pathways of meme evolution. We then consider how vocal mechanisms may constrain song evolution under five scenarios of drift and selection and examine four specific song traits for which mechanistic constraints appear to counter the diversifying effects of sexual selection. These examples illustrate the interplay between meme evolution as a diversifying influence and proximate limitations as a barrier to song divergence. We conclude by suggesting that vocal mechanisms not only constrain song evolution but also can facilitate the evolution of novel vocal features.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Planta 188 (1992), S. 546-550 
    ISSN: 1432-2048
    Keywords: Competence ; Flowering ; Floral determination ; Nicotiana (flowering)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Grafting experiments were used to investigate the relative roles of strength of flowering signal(s) and competence of buds to respond to flowering signal(s) in the development of photoperiodic and day-neutral species of Nicotiana. At the time of commitment to floral development, a flowering signal (inhibitory or promotive) could reach a critical level or terminal buds could gain competence to perceive and-or respond to an existing signal. The latter hypothesis appears to be true for day-neutral N. tabacum L. cv. Wisconsin 38, while signal strength appears to be a more critical factor for long-day N. silvestris L. Nicotiana tabacum and N. silvestris differ in terms of signal intensity at anthesis of the terminal flower. Stocks of N. silvestris promote more rapid flowering in seedling scions of both genotypes. Terminal buds of seedlings of both genotypes have the same competence to respond to the signal affecting floral development. The competence of the terminal bud of both species to respond to this signal(s) changes as a function of age.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-2048
    Keywords: Flower and inflorescence development (determination, inhibition) ; Pisum (flower and inflorescence determination)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Terminal meristems of Pisum sativum (garden pea) transit from vegetative to inflorescence development, and begin producing floral axillary meristems. Determination for inflorescence development was assessed by culturing excised buds and meristems. The first node of floral initiation (NFI) for bud expiants developing in culture and for adventitious shoots forming on cultured meristems was compared with the NFI of intact control buds. When terminal buds having eight leaf primordia were excised from plants of different ages (i.e., number of unfolded leaves) and cultured on 6-benzylaminopurine and kinetin-supplemented medium, the NFI was a function of the age of the source plant. By age 3, all terminal buds were determined for inflorescence development. Determination occurred at least eight nodes before the first axillary flower was initiated. Thus, the axillary meristems contributing to the inflorescence had not formed at the time the bud was explanted. Similar results were obtained for cultured axillary buds. In addition, meristems excised without leaf primordia from axillary buds three nodes above the cotyledons of age-3 plants gave rise to adventitious buds with an NFI of 8.3 ±0.3 nodes. In contrast seed-derived plants had an NFI of 16.5 ±0.2. Thus cells within the meristem were determined for inflorescence development. These findings indicate that determination for inflorescence development in P. sativum is a stable developmental state, separable from determination for flower development, and occurring prior to initiation of the inflorescence at the level of meristems.
    Type of Medium: Electronic Resource
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  • 4
    Publication Date: 2019-07-16
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , notRev
    Format: application/pdf
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  • 5
    Publication Date: 2017-06-07
    Description: Double plant homeodomain finger 2 (DPF2) is a highly evolutionarily conserved member of the d4 protein family that is ubiquitously expressed in human tissues and was recently shown to inhibit the myeloid differentiation of hematopoietic stem/progenitor and acute myelogenous leukemia cells. Here, we present the crystal structure of the tandem...
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
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