Evolutionary Biology

Evolution is… CHANGE Evolution is the process by which modern organisms have descended from ancient ones Darwin’s theory of evolution is widely accepted by the scientific community

Theories in Science Theory: a well tested explanation that unifies a broad range of observations – Evolution unifies all different fields of biology together due to its many lines of evidence

Evidence Supporting Evolution 1.Fossil record -shows change over time 2.Anatomical Record -comparing body structures -homology & vestigial structures -embryology & development 3.Artificial selection -human caused evolution

1. Fossil record Layers of rock contain fossils – new layers cover older ones creates a record over time – fossils show a series of organisms have lived on Earth over a long period of time

Fossil Record – Extinction of species has happened – Fossils show transitional organisms – Fossils and similar modern organisms are found in similar places

Fossils tell a story… …Of how life on Earth has changed

2. Anatomical Record Animals with different structures on the surface But when you look under the skin… It tells an evolutionary story of common ancestors

Homologous structures Structures that come from the same origin homo- = same -logous = information Forelimbs of human, cats, whales, & bats – same structure on the inside – same development in embryo – different functions on the outside – evidence of common ancestor

Compare the bones The same bones under the skin – limbs that perform different functions are built from the same bones How could these very different Animals have the same bones?

Grasshopper - Biting/Chewing Honey Bee – Lapping Nectar Mosquito – Piercing/Sucking

Homologous Structures

Embryological similarities

Vestigial Structures Apparently useless structure in one organism but served purpose in prior organisms – Human tail bone – Appendix – Pelvic bones in snakes/whales

Boa Constrictors with legs Python

Vestigial organs Hind leg bones on whale fossils Why would whales have pelvis & leg bones if they were always sea creatures?

Vestigial Structures

Analogous Structures Have identical functions and appearance but… Different development and anatomy.  structures evolved separately, and not from a recent ancestor

But don ’ t be fooled by these…  Analogous structures  look similar  on the outside  same function  different structure & development  on the inside  different origin  no evolutionary relationship Solving a similar problem with a similar solution

Fluidity of species barrier – The fact that we can create hybrids shows relation between species tigon: male tiger+female lion

3. Artificial selection –“ evolution by human selection ” “descendants” of wild mustard

Farmers and breeders were using the idea of selection to cause major changes in the features of their plants and animals over the course of decades. Farmers and breeders allowed only the plants and animals with desirable characteristics to reproduce, causing the evolution of farm stock.

Artificial Selection – Selective breeding!

Artificial Selection …and the examples keep coming! I liked breeding pigeons!

How Populations Change flipbook