Theories of Evolution Overview

Study Notes

Theories of Evolution

Fixity of Species - Proposed by Karl von Linne, it stated that all species were created by God and remained unchanging.
Inheritance of Acquired Characteristics - Jean Baptiste Lamarck proposed that organisms adapt to their environment by developing traits based on use and disuse. Changes acquired during an organism's lifetime were believed to be passed on to offspring.
Catastrophism - George Cuvier explained the presence of fossils by suggesting that catastrophic events caused extinction and subsequent repopulation by different, but similar, species.
Uniformitarianism - Charles Lyell suggested that geological forces shaping Earth today are the same as those in the past, providing evidence for long-term change.

Key Contributors

Thomas Malthus - Wrote "Essay on the Principle of Population," which explored the relationship between population growth and resource limitations.
Charles Darwin - Observed extensive biodiversity on the Galapagos Islands, leading him to develop his theory of evolution by natural selection.
Alfred Russel Wallace - Independently developed a theory of evolution similar to Darwin's.

Darwin's Theory of Evolution

Natural Selection - The mechanism by which organisms with favorable traits outcompete others for resources, leading to an increase in their survival and reproduction over time.
Tenets of Darwin's Theory
- Organisms produce more offspring than the environment can support.
- There is variation among individuals within a species.
- Traits that increase an organism's chances of survival and reproduction will be passed on to future generations.

Mendelian Genetics

Gregor Mendel - Conducted groundbreaking experiments on pea plants, revealing fundamental principles of inheritance.
Principles of Segregation - Genes exist in pairs within an individual, and each sex cell receives one copy from each pair.
- Punnett Square - Used to predict the probability of different genotypes and phenotypes.
- Alleles - Alternate forms of a gene.
- Genotype - The genetic makeup of an individual.
- Phenotype - The observable characteristics of an individual.
- Homozygous - Having two identical alleles for a trait.
- Heterozygous - Having two different alleles for a trait.
- Dominant Allele - Expressed even when paired with a recessive allele.
- Recessive Allele - Only expressed when paired with another recessive allele.
Principle of Independent Assortment - The inheritance of one trait doesn't influence the inheritance of another trait.

Cell Division

Mitosis - Somatic cells (non-sex cells) undergo mitosis, resulting in cell growth and repair.
Interphase - The period between cell divisions when DNA replicates.
- Chromosomes - Duplicate during interphase, resulting in paired chromatids.
- Centromere - The region that holds chromatids together.

Description

Explore the foundational theories of evolution and the key contributors in this quiz. From the fixity of species to the ideas of uniformitarianism, learn about the various perspectives that have shaped our understanding of evolution. Test your knowledge on the significant figures who contributed to this important scientific field.