Macroevolution & Human Evolution

Question 1

What is adaptive radiation?

Answer 1

A process in which organisms diversify rapidly from an ancestral species, producing many descendants.

Question 2

What two things allow for adaptive radiation?

Answer 2

1) ecological opportunity: the environment changes, new habitat or resources; reduced competition or predation.
2) innovation of new traits: new morphological, physiological or behavioural traits arises.

Question 3

Describe the ecological opportunity & name the three signs of adaptive radiation of the Hawaiian silverswords:

Answer 3

DESCRIPTION:
30 Hawaiian silverwords rapidly evolved after colonizing various lands.

ECOLOGICAL OPPORTUNITY:
Tarweed colonized Hawaii, and lacked competition allowing descendants to adapt to a wide range of habitats.

SIGNS OF ADAPTIVE RADIATION:

• Monophyletic group
• Rapid speciation
• Ecological diversification into many niches

Question 4

What factors gave rise to the radiation of mammals? (3)

Answer 4

1) Evolution of dentition: evolution of mammalian teeth allowed for dietary diversification and specialization in different groups.
2) Rise of the flowering plants: the evolution of angiosperms (flowering plants) provided significant sources of food & habitat for mammals.
3) Extinction of dinosaurs: the extinction of dinosaurs reduced predation pressure on mammals, and opened niches for new mammal species.

Question 5

What is background extinction?

Answer 5

extinction that occurs continuously due to normal or gradual changes.

Question 6

What is mass extinction?

Answer 6

Extinction of larger numbers of diverse organisms around the world during a short period of geological time due to extraordinary and sudden changes.

• Mass extinction can provide ecological opportunities for adaptive radiation.

Question 7

1) What are primates?

2) What two groups belong to primates?

Answer 7

1) they are a group of mammals with grasping hands and front-facing eyes.
2)
- Prosimians “before monkeys” : small tree dwelling, it includes lemurs, lorises, pottos, tarsiers
- Anthropoids “ human like” : all other primates, it includes monkeys, gorillas, chimps, humans

Question 8

What are hominids and hominins?

Answer 8

Hominins including humans are one member of the family of great apes (Hominids)

Question 9

What derived traits are found in the evolution of humans & describe them. (5)

Answer 9

1) Bipedalism: condition of having two feet for locomotion. It freed up the arms, allowing for efficient tool use, gathering and carrying food and used hands to communicate.
2) Large brain: researchers determined the brain could aid social interaction, tool use, language, responding to changing environments. Brian’s are energetically expensive and would require greater nutritional needs.
3) Use of tools: it helped homing collect food, build shelters, cook food. Use of complex tools required a large brain.
4) Reduced jaw muscles: initially massive jaw muscles were required to break down uncooked food. Later when cooking food was developed it made eating food easier, this means large jaw muscles were not required for Homo sapiens anymore.
5) Language: the evolution of communication helped humans live productively in larger groups. Information and resources was exchanged because of this. Evolution of language also required large brains.

FACT: Modern vocal cords were only present in homo sapiens

Question 10

Have Homo sapiens overlapped temporally & geographically with other hominins?

Answer 10

Yes they have. Homo sapiens originated in Africa and dispersed throughout the world. They lived alongside and interbred with other Homo sapiens.

Question 11

1) What two things are required for humans?

2) Explain how these two things caused the evolution in variation of skin colour:

Answer 11

1)
- humans need folate for healthy cells and fetal development. Folate in the skin is degraded by UV radiation.

-humans need vitamin D For healthy bones. Vitamin D is produced in the skin by UV radiation.

2)
- Near the equator: darker skin colour were adaptive
Due to the increase in UV radiation, which cause an increase in folate degradation, and vitamin D synthesis.

• Near the poles: lighter skin was adaptive, there was less UV radiation what caused less folate degradation and vitamin D synthesis.

FACT: increased skin pigments block more UV radiation