Evidence for Evolution by Natural Selection

Question 1

Evolution

Answer 1

change in allele frequency over time in a population (not all evolution is a result of natural selection e.g. evolution as a result of mutation/ changes in the genome)

Question 2

Natural Selection

Answer 2

A process whereby certain characters are favoured

Question 3

what does natural selection operate on?

Answer 3

phenotypes not genotypes

Question 4

what is the only consistent force leading to adaptation?

Answer 4

natural selection

Question 5

the importance of evolution

Answer 5

-essential to our understanding of biology; frames and explains all concepts
- vital importance in virus and bacterial resistance

Question 6

what 4 conditions are required for evolution by natural selection?

Answer 6

-Heritable characters (can these characters be passed on through generations?)
-Do the characters vary between individuals?
-Does the variation lead to differential fitness (survival and reproduction)
-Time (many generations)

Question 7

Trilobites (example of evolution in terms of phenotypes)

Answer 7

-lived for 280 million years and were extinct 250 million years ago
-over 3 million years, can see changes over time e.g. increasing number of ribs/spine-
like structures

Question 8

Evolution of Whales

Answer 8

-evolved from pakicetus (mammals that lived close to the sea)
-gradually, limbs get smaller and smaller and nose moves further back so they can breathe in water
-over time hip bone in whales was reduced as it provides no advantage
-e.g basilosaurus (tiny legs, fully aquatic and no longer goes onto the land)
-roughly 30 million years

Question 9

what science is palaeontology

Answer 9

predictive science

Question 10

discovery of Tiktaalik Roseae

Answer 10

. 380 million years ago low finned fish (like newts) yet 360 million years ago, fossil records showed land living vertebrae fish with 4 limbs
-20 million year gap suggesting due to evolution by natural selection, something must have evolved during that period before the 4 limbed fish
-In 2004, Neil Shubin set out to Ellesmere Island looking in freshwater rocks around 370 million years old that were sedimentary
-based on front limbs, fit exactly where expected

Question 11

vestiges of our evolutionary past: reptiles/ crocodiles

Answer 11

Reptiles e.g. crocodiles have a 3rd eyelid (no tear ducts); a vestige of this third eyelid can be seen in humans via the plica semilunaris (a remnant of our reptilian past)
-humans no longer need this due to the ability to blink with our tear ducts (keep our eyes moist)

Question 12

what is an example of bed design as a result of evolution

Answer 12

Left Recurrent Laryngeal Nerve (LRLN)

Question 13

larynx

Answer 13

contains vocal cords

Question 14

what is the distance of the brain to the larynx in humans

Answer 14

less than 30cm

Question 15

what is the length of the LRLN?

Answer 15

around 1m

Question 16

where is the LRLN found

Answer 16

loops round and behind the aorta

Question 17

how did the bad design of the LRLN develop?

Answer 17

in fish, the larynx evolved from the branchial arch innervated by the 4th branch of the vagus nerve however overtime the branchial arch moved down and evolved into the larynx
-overtime, the LRLN (allows us to speak) maintained its position however, due to evolution the brain moved further away from the heart

Question 18

evolution doesn’t design, it ….

Answer 18

tinkers