4-Evidence of Evolution

Evidence of

Evolution Replica of fossil skull of Homo habilis. Fossil number KNM ER 1813, found at Koobi Fora, Kenya.

Evidence of evolutionAsk yourself or an elbow partner, “Did Darwin present any evidence for evolution?”.

Evidence of evolution-1

I} The Fossil RecordDarwin saw fossils as a record of the history of life on Earth.By comparing fossils from older rock layers with fossils from younger layers, scientists could document that life on Earth has changed over time.

Evidence of evolution-22}Geographic Distribution of Living SpeciesSometimes animals on different continents living under similar ecological conditions, are exposed to similar pressures of natural selection.Because of these similar selection pressures, different animals ended up evolving certain features in common.Here we find an odd situation where two species only appear to be closely related because of their appearance.AKA CONVERGENT EVOLUTION

Evidence of evolution-33} Homologous Body Structures

Structures that have different mature forms but develop from the same embryonic tissues are called homologous structures.

Similarities and differences in homologous structures help biologists group animals according to how recently they last shared a common ancestor.

Evidence of evolution

Evidence of evolutionNot all homologous structures serve important functions.

The organs of many animals are so reduced in size that they are just vestiges, or traces, of homologous organs in other species.

These organs are called vestigial organs.

Evidence of evolution-44} Similarities in Embryology

The early stages, or embryos, of many animalswith backbones are very similar.

The same groups of embryonic cells develop in thesame order and in similar patterns to produce thetissues and organs of all vertebrates.

Ernst Haekel fudged some of his drawings!!! Still, it is clear that same groups of embryonic cells develop in the same order and in similar patterns to produce the tissues and organs of all vertebrates.

Evidence of evolution recapDarwin argued that living things have been evolving on Earth for millions of years.Evidence for this process could be found in:● the fossil record, ● the geographical distribution of living species,● homologous structures of living organisms,● and similarities in early development, or embryology.

Summary of Darwin’s TheoryIndividual organisms differ, and some of thisvariation is heritable.Organisms produce more offspring than cansurvive, and many that do survive do notreproduce.Because more organisms are produced than cansurvive, they compete for limited resources.Individuals best suited to their environment surviveand reproduce most successfully.These organisms pass their heritable traits to theiroffspring. Other individuals die or leave feweroffspring.This process of natural selection causes species tochange over time.

Species alive today are descended with modificationfrom ancestral species that lived in the distant past.This process, by which diverse species evolved fromcommon ancestors, unites all organisms on Earthinto a single tree of life.

“Grand Unifying Theory of the Life Sciences”

Multiple scientific disciplines including biology, geology and physics have confirmed and expanded most of Darwin’s hypotheses.

Today evolutionary theory is a key part of biological, biomedical and ecological scientific research.

Like all scientific theories, evolutionary theory continues to change as new data is gathered

Black Widow

Crash CourseEvidence of Evolution