Evidence for Evolution by Natural Selection - Lecture 1 Flashcards
Who came up with the idea of evolution?
French:
○ Comte de Buffon = Species vary over time
○ Georges Cuvier = Species become extinct
○ Jean-Bapiste Lamarck = Evolution by acquired characters
What are the three conditions for evolution by natural selection?
○ Heritable characters
○ Characters vary between individuals
○ Differential fitness between individuals
What is the definition of evolution?
A change in allele frequencies in a population
What are the facts about natural selection?
○ Not all evolution is caused by natural selection
○ Operates on phenotypes
○ Is the only consistent force leading to adaptations
How do trilobites show evolution?
○ Lived for 280 million years
○ Showed evolutionary changes over a short period of time (3 million years)
○ Changes = Increased number of “ribs”
How do whales show evolution?
○ Have really small hip bones
○ Pakicetus = a mammal that started to live close to the waters
Why was the tiktaalik roseae significant?
○ Was a missing link - intermediate form of fins
○ Found in Ellesmere Island in 2004 by Neil Shubin
What examples are there in human evolution?
○ Plica Semilunaris: a third eyelid that we no longer use - we now have tear ducts - from of our reptilian past
○Palmaris longus: muscle in the arms from when ancestors used their forelimbs to move around
○ Ear muscles: Once used to move the ear to locate the sources of sound
Why is the left recurrent laryngeal nerve considered “bad design”?
○ Connects the brain and larynx
○Distance from brain to larynx is <30cm
○ Loops around aorta so the length of the nerve is around 1m
○ In giraffes: 5m too long
○ In diplodocus: 15m too long
Why is the left recurrent laryngeal nerve so long?
○ Larynx evolved from branchial arch and was innervated by 4th branch vagus nerve
○ Nerve maintained its position while the function of the branchial arch changed over time
