3.2 Origins of Biodiversity

Question 1

define evolution

Answer 1

the cumulative, gradual change in the genetic composition of a species over many successive generations, ultimately giving rise to species different from the common ancestor

Question 2

natural selection notes

Answer 2

• pop show variations (i.e. not all individuals are the same)
• pop. always over-reproduce to produce excess offspring
• not enough resources available for all offspring: competition for resources
• due to variation of species some are fitter than others → those will have an advantage and will reproduce more successfully than individuals who are less fit
• those that survive have genes that give them an adaptive advantage
• genes are inherited by offspring and passed on to the next gen.
• over time there is a change in the gene pool, leading to the formation of new species

Question 3

define speciation

Answer 3

the formation of new species when populations of a species become isolated and evolve differently

Question 4

geographical isolation

Answer 4

a physical barrier that leads to populations becoming separated, eventually leading to speciation

causes include plate activity, the formation of mountains, seas, lakes, rivers and deserts

Question 5

plate tectonics

Answer 5

the movement of eight major and several minor internally rigid plates of the Earths lithosphere in relation to each other and to the partially mobile asthenosphere below.

Question 6

list 3 physical factors that might separate populations

Answer 6

• mountain ranges
• bodies of water
• natural events

Question 7

temporal isolation

Answer 7

species that live lives during different times of day, and therefore dont interbreed

Question 8

behavioural isolation

Answer 8

courtship rituals between two species vary

Question 9

constructive plate margins

Answer 9

plates move apart

Question 10

destructive plate margins

Answer 10

plates move together

Question 11

collision plate margins

Answer 11

plates collide

Question 12

collision of plates can lead to:

Answer 12

• uplift and mountain formation → form physical barrier which isolates populations
  + also creates new habitats, promoting biodiversity (adaptation to new habitats the occurs through natural selection)
• spread of species through the creation of land bridges → mixing of gene pools and possible hybridisation

Question 13

plate activity can:

Answer 13

• create new islands usually through volcanic activity
  → can lead to adaptations to fill new habitats/niches
• movement of plates → evolutionary changes, for example the northward movement of the Australian plate

Question 14

mass extinction definition

Answer 14

events in which 75% of the species on Earth disappear within a geologically short time period, usually between a few hundred thousand to a few million years

Question 15

how many mass extinctions have there been

Answer 15

5

Question 16

the Sixth Extinction

Answer 16

• population of many species decline
• related to human activity
• species unable to adapt

Question 17

why is the Sixth Extinction different?

Answer 17

caused by a single species (humans):
- climate change
- deforistation (habitat loss)
- poaching
- hunting
- overfishing

Question 18

2 phases of the Sixth Extinction

Answer 18

1: began when the first modern humans began to disperse to different parts of the world about 100000 years ago

2: about 10000 years ago when humans turned to agriculture to grow food

Question 19

possible causes of mass extinctions

Answer 19

• asteriod impact
• volcanic activity leading to climate change
• extreme temperature changes
• sea level change due to glacier formation