Evolution
Evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organization, including species, individual organisms and molecules such as DNA and proteins.
Life on Earth originated and then evolved from a universal common ancestor approximately 3.7 billion years ago. Repeated speciation and the divergence of life can be inferred from shared sets of biochemical and morphological traits, or by shared DNA sequences. These homologous traits and sequences are more similar among species that share a more recent common ancestor, and can be used to reconstruct evolutionary histories, using both existing species and the fossil record. Existing patterns of biodiversity have been shaped both by speciation and by extinction.
Charles Darwin was the first to formulate a scientific argument for the theory of evolution by means of natural selection. Evolution by natural selection is a process that is inferred from three facts about populations:
(1) more offspring are produced than can possibly survive,
(2) traits vary among individuals, leading to differential rates of survival and reproduction, and
(3) trait differences are heritable.
Thus, when members of a population die they are replaced by the progeny of parents that were better adapted to survive and reproduce in the environment in which natural selection took place. This process creates and preserves traits that are seemingly fitted for the functional roles they perform.
Natural selection is the only known cause of adaptation, but not the only known cause of evolution. Other, notable adaptive causes of evolution include mutation and genetic drift.
In the early 20th century, genetics was integrated with Darwin's theory of evolution by natural selection through the discipline of population genetics. The importance of natural selection as a cause of evolution was accepted into other branches of biology. Moreover, previously held notions about evolution, such as orthogenesis and "progress" became obsolete.
Scientists continue to study various aspects of evolution by forming and testing hypotheses, constructing scientific theories, using observational data, and performing experiments in both the field and the laboratory. Biologists agree that descent with modification is one of the most reliably established facts in science. Discoveries in evolutionary biology have made a significant impact not just within the traditional branches of biology, but also in other academic disciplines (e.g., anthropology and psychology) and on society at large.
Multiple-Choice Question:
(A) Descent with modification (B) Natural selection
(C) Progress (D) Orthogenesis
(A) they are replaced by the progeny of parents
(B) they reproduce in the environment in which natural selection took place.
(C) they are reborn again
(D) the population comes to an end
(A) Progress (B) Genetics (C) Mutation (D) Diversity
Multiple Choice Questions (with more than one option):
(A) Extinction (B) Natural selection
(C) Mutation (D) Genetic drift
(A) traits vary among individuals
(B) Natural selection is the only known cause of evolution
(C) Genetics is the only cause of evolution
(D) Natural selection is the cause of adaptation
Fill in the blanks:
____ has been shaped both by speciation and by extinction.
____ is one of the previously held notions about evolution.
____ differences are heritable.
Divergence of life can be inferred from shared _____ sequences.
____was the first to argue for the theory of evolution by means of natural selection.
True/False:
Evolutions give rise to diversity at every level of biological organization.
Discoveries in evolution have made an impact on society at large.
Genetics can never be integrated with Darwin's theory.
Natural selection is the only known cause of adaptation.
The rate of survival and reproduction among the individuals does not vary.
Answer key
(1)–(A); (2)–(A); (3)–(D); (4)–(B,C,D); (5)–(A,D); (6)–existing patterns of biodiversity; (7)–orthogenesis; (8)–Trait; (9)–dna; (10)–charles Darwin; (11)–True; (12)–True; (13)–False; (14)–False; (15)–False
