Biological Interactions

Question 1

limiting factor

Answer 1

key physical factor determining survival/growth/reproduction of an organism

Question 2

Environmental gradient

Answer 2

temperature, moisture, light

Question 3

Density

Answer 3

population abundance per unit area

Question 4

carrying capacity

Answer 4

number of individuals / m^2 or ha

Question 5

Broad environmental range

Answer 5

• ecologically tolerant
• eurytopic
• generalist

Question 6

narrow environmental range

Answer 6

• ecologically intolerant
• stenotopic
• specialist

Question 7

niche

Answer 7

• 2 dimensional representation of species environment

Question 8

Predation

Answer 8

geographic range of predator is limited to geographic range of prey

Question 9

stenophagus predator

Answer 9

• narrow range of prey species

- most plant eating insects

Question 10

euryphagous predator

Answer 10

• most birds and mammals

- few exceptions

Question 11

Why are some animals stenophagous?

Answer 11

• Prey with highest ratio of food energy relative to energy used for foraging: Optimal Foraging Theory
• Insects with resistance to toxins of 1 plant species
• Micro-environmental conditions for whole life-cycle provided by a single plant

Question 12

Competition

Answer 12

• interaction between populations where both suffer

- for a common resources that is limited

Question 13

intraspecific competition

Answer 13

members of same species

Question 14

interspecific competition

Answer 14

members of different species

Question 15

competitive exclusion

Answer 15

no 2 species can co-exist on same limiting resources

Question 16

scramble competition

Answer 16

• resource competition
• when 2 or more populations use the same resource (food or territory) which is in limited supply
• indirect competition
• 1 population reduces the amount of food/territory available to the other

Question 17

red squirrel

Answer 17

• prefers coniferous forest but also lives in deciduous forest
• major decline in geographic range 1920-1925 due to disease
• grey squirrel took advantage of this decline

Question 18

grey squirrel

Answer 18

• adapted to deciduous forest but can colonise conifers
• introduced from USA to UK late 19th & early 20th century
• expanded by out-competing red squirrel for resources

Question 19

how does grey squirrel out compete red squirrel

Answer 19

• grey better at foraging for acorns
• red prefer hazelnut
• red less able to neutralise acorn polyphenols
• post war decline in hazel coppicing

Question 20

contest competition

Answer 20

• interference competition
• direct interaction between individuals (plants in competition for light)
  Allelopathy:
• chemical released by one plant species to inhibit growth of another plant species
• phytotoxic substances

Question 21

overlapping rages of caiman species

Answer 21

• different environmental niche
• different prey
• not competing for the same resource

Question 22

symbiosis

Answer 22

• close association between 2 species, resulting from co-evolution
• impacts geographic distribution

Question 23

mutualism

Answer 23

benefits both specie

• lichen
• honey bee/humming birds and plants

Question 24

commensalism

Answer 24

benefits one species but no impact on the other

- clown fish and sea anemone

Question 25

parasitism

Answer 25

benefits one species at expense of the other

• tick
• lice
• tape worm

Question 26

mimicry

Answer 26

• one species evolves the appearance or behaviour of another

Question 27

Batesian mimicry

Answer 27

• one species that is neither poisonous or unpalatable evolves same appearance as another that is poisonous/unpalatable

Question 28

Muelllerian mimicry

Answer 28

• both species evolve same appearance and equally unpalatable or poisonous to common predator