3.1 - Biodiversity and evolution

Question 1

Biodiversity

Answer 1

Total diversity of living systems
* three levels: habitat diversity, species diversity, genetic diversity

Question 2

Species richness

Answer 2

The number of species of different animals, plants, fungi and microorganisms in ecosystems

Question 3

Species evenness

Answer 3

The relative proportion of individuals of each species

Question 4

Ecosystem resilience

Answer 4

The capacity of an ecosystem to withstand disturbances and still maintain the same function of organisms working together to maintain a balanced, sustainable ecosystem

Question 5

Species diversity

Answer 5

A product of species richness and evenness

Question 6

Evolution

Answer 6

Cumulative change (builds up over time) in the heritable characteristics (gene and allele frequency/pool) of a population or species

Question 7

Natural selection

Answer 7

Where the organisms that are more adapted to the environment have an advantage over those that are less adapted, they survive, flourish and reproduce

Question 8

Diversity index

Answer 8

Gives a quantified estimate of biological variability in space or time and describes and compares communities

Question 9

What can low diversity in comparing communities be a sign of?

Answer 9

• pollution
• eutrophication
• recent colonisation of a site

Question 10

Value of diversity index (D)

Answer 10

higher where there is greater richness (number of species) and evenness (similar abundance)

Question 11

Simpson’s reciprocal diversity index

Answer 11

numerical value that can be used to measure species richness and evenness (1 is the lowest possible value)

Question 12

Genetic diversity

Answer 12

The range of genetic material present in a gene pool or population of a species

Question 13

How do individuals play a role in genetic diversity?

Answer 13

Each individual in a species has a slightly different set of genes from any other individual in the species
* more individuals = higher genetic diversity = bigger gene pool

Question 14

How do populations play a role in genetic diversity?

Answer 14

If a species is made up of two or more different populations in different places, each population will have a different genetic make-up
* their conservation = maximise genetic diversity

Question 15

Cheetah (Acinonyx jubatus) as an example of genetic diversity

Answer 15

Low genetic diversity
* population bottleneck (sharp reduction in population) around 10,000 years ago at the end of the last ice age
* now: habitat encoarchment and poaching have further reduced
* future: female cheetahs bear a single litter with multiple fathers - may be behaviour to increase genetic diversity

Question 16

Domestic dogs (Canis familiaris) as an example of genetic diversity

Answer 16

High genetic diversity
* selectively bred by humans for over 15,000 years
* Pleistocene wolves were evolutionary ancestors of all dogs
* wide range of phenotypes

Question 17

Habitat diversity

Answer 17

The range of different habitats per unit area in a particular ecosystem or biome

Question 18

How can humans alter genetic diversity? (2)

Answer 18

• artificial breeding (e.g. domesticated dogs)
• genetic engineering (e.g. altering the DNA of bacteria)

Question 19

Consequences of human interventions in genetic diversity?

Answer 19

Reduces variation in genotypes or can produce identical genotypes (clones)
* advantage: may produce high-yielding crop or animal
* disadvantage: disease strike and the whole population is susceptible to it

Question 20

Resilient ecosystem

Answer 20

Can absorb disturbances while managing to maintain critical funtions

Question 21

Sustainable ecosystem

Answer 21

In the face of normal disturbances will manage and maintain critical functions

Question 22

Healthy ecosystem

Answer 22

Diverse and provides plenty of beneficial services for its living organisms

Question 23

Pioneer species

Answer 23

The first to colonize newly created environments or recently disturbed environments during the processes of primary succession and secondary succession

Question 24

Factors affecting biodiversity and ecosystem resilience (4 & explanation)

Answer 24

1. Complexity of exosystem - more complex, more resilient to the loss of one species due to ability to replace it
2. Stage of succession - initially only pioneer species until conditions become more favourable for climax communtiy (here, species composition is stable)
3. Limiting factors and stability - access to raw materials and abiotic factors as well as environmental disasters can lower resilience
4. Age of the ecosystem - the older the ecosystem, the greater the biodiversity due to undisturbed duration

Question 25

Advantages of high biodiversity (3)

Answer 25

• resilience and stability due to the range of plants present, of which some will survive drought, floods, insect attack or disease
• genetic diversity
• plants will have deep roots and can cycle nutrients and bring them to the surface making them available for other plants

Question 26

Disadvantages of high biodiversity (2)

Answer 26

• diversity can be the result of fragmentation of a habitat or degredation when species richness is due to pioneer species invading bare areas quickly
• managing grazing (grassland for pasturage) can be difficult

Question 27

Principles of natural selection (4)

Answer 27

1. Variation - resulting from genetic diversity
2. Overproduction - more offspring produced than can be supported
3. Selection - competition limits survival
4. Reproduction - surviving organisms reproduce and pass on genes

Question 28

Speciation

Answer 28

The process by which new species form

Question 29

Endemic species

Answer 29

Only found in one geographical location and nowhere else on Earth