THEORY XIX CENTURY EVOLUTIONARY.
Lamarck in the nineteenth century developed the theory of acquired characteristics.
· · Example of the giraffe, craning his neck to reach the branches, the giraffe get a long neck and legs after their children inherit.
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based on the inheritance of acquired characteristics as a result of performing a particular function.
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Darwin developed an alternative theory which is based on natural selection.
- There are small differences in the individuals of the same species.
- Set a struggle for survival.
- Some forms are more successful than others and survive.
- The species are changing continuously and gradually.
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Darwinism is based that individuals genetically fittest, are those who leave offspring.
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ARGUMENTS FOR EVOLUTION.
By studying paleontology fossils of organisms that lived at different times can be known changes that have suffered the species over time. TESTING
anatomic and embryologic.
Comparative Anatomy: a fin of a fish, a human arm and a leg of cat has similar structures.
Just as the embryo of a bird, a rabbit and a be humans are very similar.
All this shows a common origin.
TESTS biochemistry and genetics.
The similarity or resemblance between proteins and DNA of all living things gives us arguments for a common origin for all.
ORIGIN OF VARIABILITY.
hereditary differences between individuals of a species are the raw material on which natural selection acts, without such hereditary variations can not be evolution.
Mutations: constitute the raw material evolution, the source of the new features in populations and the burden of new species. Sexual
: Although not produce new genes, the variation increases as new combinations of genes originate.
synthetic theory.
Neo-Darwinism proposes that natural selection and mutations are mutually complementary processes, but none of them alone can explain the evolution.
· · evolutionary unit is not an individual but the population.
· · individuals are carriers of different alleles, differences that arise by mutation.
· · Some phenotypes are more likely to leave offspring, so they are selected.
· · The evolution is caused by a gradual change in the genetic structure of populations.
SPECIATION: formation of a new species, which must meet the following stages:
- Isolation of populations.
- gradual differentiation.
- Two different species. **********************************************
************************************** Vocabulary
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· Paleontology: studies fossils. phylogenetic
· Series: fossil assemblage will serve to showcase the evolution of the species.
· Fossil: other mineral that keeps the track of a living being.
· Biogeography: studying the variety of living things.
· Mutations: is produced by the structure of genes inherited.
· Asexual reproduction: reproduction in which a single parent produces identical offspring himself.
· Sexual reproduction: is formed, from two cells, descendants car acters other than their parents.
· Alleles: and s one of several alternative states of the same gene.
· Phenotype: is the expression of the genotype in a given environment.
· Genotype: is the genetic content of an individual, in the form of DNA.
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