Evidence of Evolution

EVO-2.C: Describe structural and functional evidence on cellular and molecular levels that provides evidence for the common ancestry of all eukaryotes.
EVO-1M: Describe the types of data that provide evidence for evolution.
EVO-1.N: Explain how morphological, biochemical, and geological data provide evidence that organisms have changed over time.
EVO-2.B: Describe the fundamental molecular and cellular features shared across all domains of life, which provide evidence of common ancestry.

Evolution is defined as the process of successive changes of characteristics of populations of species over long periods of time.
Over time, evolution can lead to the formation of a new species from a common ancestor, a process referred to as speciation.

A common ancestor is a species from which one or more new species evolves.
The degree of relatedness between two species is determined by how recently they shared a common ancestor.

Inheritance of Acquired Characteristics: Individuals can acquire new traits during their lifetime based on environmental changes. These traits would then be inherited by offspring.
Lamarck posited that body parts or organs would develop or degenerate based on their usage or disuse.

Charles Darwin was a key figure in the development of evolutionary theory based on natural selection.
Darwin conducted research inspired by his voyage to South America, particularly focusing on the Galapagos finches, which demonstrated variation in traits.

Among ancestral giraffes, some individuals possessed longer necks. Those with longer necks were more successful in reproducing and thus left more offspring that also had long necks.
This process occurred repeatedly across generations, providing evidence for natural selection.

There are five main sources of evidence supporting evolution:

Fossils serve as a historical record, indicating the gradual changes in organisms and among species over time.
Radioactive dating is employed to determine the age of fossils.
Recently discovered fossils create a series that trace modern species' evolution from extinct ancestors.
Transitional fossils are crucial as they document intermediate stages in the evolution of modern species.

The fossil record shows different evolutionary patterns: - Adaptive Radiation: A small group of species evolves into various species in different habitats in a relatively short period. - Gradualism: Evolution occurs at a slow and steady pace along a single lineage. - Punctuated Equilibrium: Species undergo long periods of stability (stasis) interrupted by rapid changes.

Biogeography studies how species are distributed around the world and the factors influencing these distributions.
Observations from Darwin’s travels revealed that organisms on islands shared common features with mainland species but were distinct, indicating adaptive evolution in response to different environmental pressures.

The study of embryonic development traits across different organisms shows commonalities that provide evidence of shared ancestry.
Similar embryonic cells develop in the same order and pattern, producing homologous tissues and organs across species.

Comparative anatomy examines the similarities and differences in anatomical structures across species to determine their evolutionary relationships.

Homologous Structures: Similar structures inherited from a common ancestor but may serve different functions in different species.
Analogous Structures: Structures that evolved independently in various organisms due to adaptation to similar environments or ecological roles, highlighting convergence despite a lack of common ancestry.
Vestigial Structures: These are anatomical features that were once necessary for survival but have lost their utility over time, providing clues to evolutionary history.

Molecular homology entails the study of similarity between DNA and amino acid sequences across different species, indicating a common ancestor from which these sequences originated.
A comparison of DNA reveals the following similarities between species: - 99.5% shared DNA with other humans - 98.5% shared DNA with chimpanzees - 80% shared DNA with mice - 63% shared DNA with zebrafish - 39% shared DNA with fruit flies - 17% shared DNA with mustard grass