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Derived traits show significant differences from the original "primitive" condition of an ancestral trait found in the common ancestor, implying that the trait has undergone extensive adaptation during the clade's evolutionary history to reach its derivative condition. Both terms are relative: a derived trait for one clade may be an ancestral ...
Life history characteristics will, in some cases, change according to the population density, since genotypes with the highest fitness at high population densities will not have the highest fitness at low population densities. [16] Other conditions, such as the stability of the environment, will lead to selection for certain life history traits.
The evolution of biological complexity is one important outcome of the process of evolution. [1] Evolution has produced some remarkably complex organisms – although the actual level of complexity is very hard to define or measure accurately in biology, with properties such as gene content, the number of cell types or morphology all proposed as possible metrics.
The history of biology traces the study of the living world from ancient to modern times. Although the concept of biology as a single coherent field arose in the 19th century, the biological sciences emerged from traditions of medicine and natural history reaching back to Ayurveda, ancient Egyptian medicine and the works of Aristotle, Theophrastus and Galen in the ancient Greco-Roman world.
Evolutionary arms race – Competition of sets of genes, traits, or species, that develop adaptations against each other; Evolutionary capacitance – Evolutionary biology hypothesis; Evolutionary fauna; Evolutionary pressure – Any cause that reduces reproductive success in a proportion of a population
The concept of evolutionary grades arises in the context of phylogenetics: the study of the evolutionary history and relationships among or within groups of organisms. These relationships are determined by phylogenetic inference methods that focus on observed heritable traits, such as DNA sequences, protein amino acid sequences, or morphology.
Evolutionary progress as a tree of life. Ernst Haeckel, 1866 Lamarck's two-factor theory involves 1) a complexifying force that drives animal body plans towards higher levels (orthogenesis) creating a ladder of phyla, and 2) an adaptive force that causes animals with a given body plan to adapt to circumstances (use and disuse, inheritance of acquired characteristics), creating a diversity of ...
The theory of recapitulation, also called the biogenetic law or embryological parallelism—often expressed using Ernst Haeckel's phrase "ontogeny recapitulates phylogeny"—is a historical hypothesis that the development of the embryo of an animal, from fertilization to gestation or hatching (), goes through stages resembling or representing successive adult stages in the evolution of the ...