L010 History of Life 3-11

L010 History of Life 3-11 - 1 Lecture 10 History of Life...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: 4/14/11 1 Lecture 10: History of Life and Macroevolution Fins Limbs History of Life All life forms share a common ancestor. What was this common ancestor like? When did it exist? What was the common ancestor of all life forms like? Difficult to tell from the fossil record Oldest fossil organisms already seem highly derived. Can use a phylogeny to infer what the ancestor was like. Phylogeny of all Life There are three main branches of life: Bacteria Archaea Fig 17.18 What was the common ancestor of all life forms like? Ancestor: – probably much like modern bacteria – contained DNA – fairly complete metabolism – more like Bacteria, less like Eucarya/Archaea living cells fossils When did the common ancestor frst appear? Difficult to tell from fossil record. First fossils (3.5 billion years old) were already highly derived. Based on fossils and phylogeny, common ancestor probably 4.5 - 3.5 billion years ago Not single species but community of species that traded genes (lateral or horizontal transfer) 4/14/11 2 History of Life Earth is 4.6 billion years old. Thus, life appeared very soon after the formation of the earth. 1 2 3 4 4.6 Origin of earth Common ancestor Billions of years ago History of Life Evolution of the Eucarya (2 billion years old) involved major innovations – linear DNA – organelles (chloroplasts and mitochondria were obtained by acquiring symbiotic bacteria) History of Life • For billions of years, life remained unicellular. • First multicellular life didn ` t appear until 565 million years ago History of Life 1 2 3 4 4.6 Billions of years ago Origin of earth Common ancestor First Multicellular Organisms 565 million years ago History of Life • over the next 40 million years, an explosive radiation of forms representing different body plans • termed the Cambrian Explosion (1% of earth history) History of Life Some forms with no modern-day close relatives. 4/14/11 2 History of Life Earth is 4.6 billion years old. Thus, life appeared very soon after the formation of the earth. 1 2 3 4 4.6 Origin of earth Common ancestor Billions of years ago History of Life Evolution of the Eucarya (2 billion years old) involved major innovations – linear DNA – organelles (chloroplasts and mitochondria were obtained by acquiring symbiotic bacteria) History of Life • For billions of years, life remained unicellular....
View Full Document

{[ snackBarMessage ]}

Page1 / 12

L010 History of Life 3-11 - 1 Lecture 10 History of Life...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online