Evidence for Evolution

Question 1

What’s the evidence for evolution?

Answer 1

• Direct evidence
• Biogeology
• Fossil Record
• Homology
• Embryology
• Comparative Behavior and Biochemistry

Question 2

Guppy background

Answer 2

• Guppies are small freshwater fish native to South America
• Females prefer to mate with bright spotty males, however these males are more prone to being caught by males
• Pools with predators have less spotty and duller males

Question 3

Direct Experiment

Answer 3

• John Endler created artificial pools with a random selection of guppies, followed by the introduction of predators a while late
• Before, the predator introduction, over generations, the males were getting brighter and spottier.
• A small predator “Rivulus” had no effect as it preyed on immature fish
• A larger predator preyed on brighter males, leading to duller and duller generations
• This is direct evidence for evolutionary change over a short timescale

Question 4

Biogeology

Answer 4

• Living organisms are not distrubated evenly into every potiential habitat
• But similar organisms occur on different continents (e.g., bears). This makes sense when you consider continental drift
• Oceanic islands usually have endemic species however some islands join and drift away again, allow short-term animal migration
• Animal species may also have migrated to islands and become isolated (Madagascar)
• Isolated islands may show convergent evolution

Question 5

Ratites

Answer 5

• Example of biogeology evolution
• They include emus, ostriches and cassowary
• They are similar in niches, diet and behaviour
• but found in different continents

Question 6

Fossil Record

Answer 6

• A direct but fragmentary record of evolution
• Footprints can be fossilised
• Layers of known age can to be used to date fossils (Strataigraphy)
• Archaeopteryx links dinosaurs and birds. Missing links can be found
• Burgress shale fauna were ocean life 525 - 515 milllions of years ago. Well perserved with findings of increased size, morphological complexicity and diversity

Question 7

Homology

Answer 7

• Simularity between structures of related organims, such as common limb structures.
• These charactertistics are called Homologous
• Vestigal structures may be poorly developed in some species but developed and functional in others (e.g., tail bone in humans vs monkey tails)
• Homoplastic characteristics are similar in function but evolved seperate to one another (bat vs bird wings)

Question 8

Embryology

Answer 8

• Comparision of vertebrate embryos
• Gill silts and tails are common in most embroyos including humans

Question 9

Comparative behavior and biochemistry

Answer 9

• Social behavioour, the greater the simularity the closer the relation
• Mitochondria and haemoglobin may be compared