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Alternation between a multicellular diploid and a multicellular haploid generation is never encountered in animals. [33] In some animals, there is an alternation between parthenogenic and sexually reproductive phases , for instance in salps and doliolids (class Thaliacea). Both phases are diploid.
Published online in the Image & Video Library of The American Society for Cell Biology; The Image & Video Library Archived 2011-06-10 at the Wayback Machine of The American Society for Cell Biology contains many videos showing the cell division. The Cell Division of the Cell Image Library; Images : Calanthe discolor Lindl. – Flavon's Secret ...
When generation overlapping is incorporated in this model, the substitution rate does change with population size fluctuations. The substitution rate increases when the population size transits from small to large, with a high survival probability and when the population size transits from large to small, with a low survival probability. [11]
Coalescent theory is a model of how alleles sampled from a population may have originated from a common ancestor.In the simplest case, coalescent theory assumes no recombination, no natural selection, and no gene flow or population structure, meaning that each variant is equally likely to have been passed from one generation to the next.
Morphogenesis (from the Greek morphê shape and genesis creation, literally "the generation of form") is the biological process that causes a cell, tissue or organism to develop its shape. It is one of three fundamental aspects of developmental biology along with the control of tissue growth and patterning of cellular differentiation.
In developmental biology, pattern formation refers to the generation of complex organizations of cell fates in space and time. The role of genes in pattern formation is an aspect of morphogenesis , the creation of diverse anatomies from similar genes, now being explored in the science of evolutionary developmental biology or evo-devo.
The most common formulation of a branching process is that of the Galton–Watson process.Let Z n denote the state in period n (often interpreted as the size of generation n), and let X n,i be a random variable denoting the number of direct successors of member i in period n, where X n,i are independent and identically distributed random variables over all n ∈{ 0, 1, 2, ...} and i ∈ {1 ...
This glossary of biology terms is a list of definitions of fundamental terms and concepts used in biology, the study of life and of living organisms.It is intended as introductory material for novices; for more specific and technical definitions from sub-disciplines and related fields, see Glossary of cell biology, Glossary of genetics, Glossary of evolutionary biology, Glossary of ecology ...