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448 results on '"Badyaev, Alexander V."'

1. Cycles of external dependency drive evolution of avian carotenoid networks

Author

Badyaev, Alexander V, Posner, Alexander B, Morrison, Erin S, and Higginson, Dawn M

Subjects
BRII recipient: Posner
Abstract

All organisms depend on input of exogenous compounds that cannot be internally produced. Gain and loss of such dependencies structure ecological communities and drive species’ evolution, yet the evolution of mechanisms that accommodate these variable dependencies remain elusive. Here, we show that historical cycles of gains and losses of external dependencies in avian carotenoid-producing networks are linked to their evolutionary diversification. This occurs because internalization of metabolic controls—produced when gains in redundancy of dietary inputs coincide with increased branching of their derived products—enables rapid and sustainable exploration of an existing network by shielding it from environmental fluctuations in inputs. Correspondingly, loss of internal controls constrains evolution to the rate of the gains and losses of dietary precursors. Because internalization of a network’s controls necessarily bridges diet-specific enzymatic modules within a network, it structurally links local adaptation and continuous evolution even for traits fully dependent on contingent external inputs.

Published
2019

50. The Origin and Evolution of Cellular Differentiation in the Volvocine Green Algae

Author

Badyaev, Alexander V., Dieckmann, Carol L., Masel, Joanna, Nedelcu, Aurora M., Davison, Dinah R., Badyaev, Alexander V., Dieckmann, Carol L., Masel, Joanna, Nedelcu, Aurora M., and Davison, Dinah R.

Abstract

During the evolution of multicellularity, the unit of selection transitions from that of the single cell to that of the integrated multicellular organism. Cellular specialization mediates this transition, as the evolution of differentiated cell types leads to fitness becoming a property of the multicellular organism. How does cellular specialization evolve? While we know that genetic changes result in the development of new cell types, it remains unclear whether the development of a new cell type can be ancestrally plastic prior to coming under developmental-genetic control via genetic assimilation. We use the volvocine green algae as a model system to address the overarching question of whether the plastic development of a new cell type preceded its fixation via genetic assimilation. Previous research on the evolution of cellular differentiation in this clade has determined that a gene necessary for somatic cell development is present in species with and without soma and that an ancestral stress response was co-opted during the evolution of somatic differentiation. This raises the possibility that somatic cells may have originated as a plastic trait prior to coming under developmental-genetic control. Here, I show that Eudorina species previously characterized as undifferentiated develop a small proportion of cells resembling soma following exposure to cold shock, an environmental stressor. We also find that the offspring of cold-shocked colonies (but not the grand-offspring) also develop somatic-like cells. We show that these cells are morphologically consistent with the somatic cells seen in closely related species that are obligately differentiated. We find that somatic-like cells in cold-shocked colonies are controlled by cell-level, temporal regulation while the production of somatic-like cells in the offspring of cold-shocked colonies are controlled by group-level, developmental regulation induced by the maternal environment. We propose that cell-level contro

Published
2022

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