2.1 species and populations

Question 1

Definitions for species, population, carrying capacity, limiting factors, and habitat

Answer 1

• Species = group of organisms with common characteristics that can interbreed to produce fertile offspring
• Population = a group of individuals of the same species living in the same area at the same time
• Carrying Capacity = the maximum number of individuals of a species that the environment can sustainably support in a given area
• Limiting Factors = the resources in the environment that limit the growth, abundance, and distribution of organisms/populations in an ecosystem
• Habitat = environment in which a species usually lives

Question 2

biotic and abiotic + examples

Answer 2

Biotic: interactions between the organisms - between producers, consumers, decomposers
Abiotic: non-living, physical factors that influence organisms and ecosystems
- temp, sunlight, water, ph, salinity

Question 3

What is a niche, fundamental and a realized niche?

Answer 3

Niche = role an organism plays + position it holds in the environment
- includes all interactions the organism has with the abiotic and biotic environment

Fundamental Niche = the environmental conditions under which a species can live

Realized Niche = actual conditions in which a species exists due to biotic interactions

Question 4

Explain how non-living factors influence organisms and ecosystems

Answer 4

1. Temperature –> affects the metabolism, growth, and behavior - different species have optimal temps for normal function
2. Water –> essential for nutrient uptake and hydration
3. Sunlight –> primary source of energy for most ecosystems (photosynthesis) - the intensity, duration, and wavelength of sunlight affect the rate of photosynthesis and thus primary productivity
4. Soil –> properties such as texture, composition, pH, moisture content, and nutrient levels influence plant growth

Question 5

J-shape

Answer 5

• exponential pop. growth
• are not sustained in the real world (may occur for short periods but a crash is inevitable)

Question 6

S-shape

Answer 6

• logistic pop. growth
• pop. growth rate accelerates then slows down when it reaches max carrying capacity

Question 7

Discuss how populations change and interact with the physical environment

Answer 7

1. Resource Availability –> pop increase = increase in resource demand = competition
2. Abiotic Factors
   - e.g. temperature affects metabolic rates and reproductive cycles
   - climate change or natural disasters can impact population by altering habitat suitability and resource availability
3. Migration and Dispersal –> populations may migrate or disperse in response to environmental changes, resource availability, etc.

Question 8

density-independent factors impacting population growth

Answer 8

abiotic in nature + impact pop. no matter how large they are
- climate, weather, natural disasters

Question 9

density dependant factors impacting population growth

Answer 9

biotic interactions + impact they have varies on how dense a population is (denser the pop. the greater their impact)
- predation, herbivory, mutualism, parasitism, disease, competition

Question 10

Describe predation, herbivory, parasitism, mutualism, and disease

Answer 10

• Predation = one organism hunts and kills another (wolves hunting rabbits)
• Herbivory = animals that consume plants (elephants: bark, leaves, roots, grass)
• Parasitism = organism takes nutrients from another (host) without killing them (lice, ticks)
• Mutualism = two organisms of different species co-existing (bacteria + cows, cows have better digested food)
• Disease = departure of normal state of functioning (ebolavirus)

Question 11

competition

Answer 11

= competition for resources in a limited supply
- inter-species: dif. species (lions and hyenas)
- intra-species: same species (trees)

Question 12

Explain how the species interactions impact population dynamics and carrying capacity

Answer 12

1. Competition
   - inter-species: dif. species (lions and hyenas)
   - intra-species: same species (trees)
2. Predation
   - population control –> happens via negative feedback, like wolves and rabbits
   - increase in rabbit pop. –> more food for wolves –> increase in wolf pop. –> decrease in rabbit pop. –> decrease in wolf pop.
3. Mutualism
   - Can enhance the survival, growth, and reproduction of species involved –> e.g. pollination by insects benefits both plants and pollinators –> increased reproductive success for the plants and a food source for the pollinators