BISC 208: Mini-Exam 2 Study Guide 2024-2025
Levels of Study (Ecology)
- organismal ecology: individuals interacting with each other and their environment?
• explore the morphological, physiological, and behavioral adaptations that allow organisms to
live in a particular area
• ex: salmon migrate from saltwater to freshwater environments to breed
- population ecology: how and why does population size change over space and time?
• population: a group of individuals of the same species that live in the same area at the same
time
• ex: each salmon (female) produces thousands of eggs. on average, only a few offspring will
survive to return to the same steam to breed
- community ecology: how do species interact, and what are the consequences?
• biological community: a community consists of the species that interact with one another in a
particular area
• asks questions about predation, parasitism, competition, and how species respond to physical
disturbances
• ex: salmon are prey as well as predators
- ecosystem ecology: how does energy flow and how do nutrients cycle through the local
environment?
• the whole area including abiotic and biotic factors
• ex: salmon die and then decompose, releasing nutrients that are used by other organisms
- global ecology: how is the biosphere affected by global changes in nutrient cycling and
climate?
• ex: worldwide populations of salmon are affected by climate change
- conservation biology: the effort to study, preserve, and restore threatened populations,
communities, and ecosystems
Abiotic Factors and Niches
,- no species lives everywhere on Earth
- the suite of conditions a species can tolerate factor into an organism's niche
- abiotic (non-living) factors explain only part of species distributions
Biotic Factors
- biotic ("living") factors-interactions with other organisms limit distributions
- competition
- reproductive requirements
- parasitism
- other interactions
Communities Change Over Time → Ecological Succession
- prairies (good examples)
- long-term effects of fire on a tallgrass prairie community
Trophic interactions can also have extraordinary influence on niche availability and diversity
- trophic: different levels of species (in terms of energy)
How does energy flow through ecosystems?
- primary producer → primary consumer → secondary consumer → tertiary consumer
- energy dissipates as it flows through the system as heat
- nutrients cycle through trophic levels
- each level decomposes to provide nutrients to primary producers
- energy flow model: energy moves through organisms in a form of biomass
- a primary producer (autotroph): an organism that can synthesize its own food from inorganic
sources
- consumers eat living organisms
,• primary consumers eat primary producers
• secondary consumers eat primary consumers
• tertiary consumers eat secondary consumers
- decomposers, or detritivores, feed on detritus, the waste products, or dead remains of other
organisms
- organisms that obtain energy from the same type of source occupy the same trophic
("feeding") level
The Pyramid of Productivity
- all ecosystems share a characteristic pattern
• the total biomass produced per year is greatest at the lowest trophic level and declines at
higher levels
- this pattern occurs because most of the energy consumed is used for growth and reproduction
• the amount of biomass produced at each subsequent trophic level must be less than the
amount at the previous level (10% rule)
Biomagnification
- biomagnification: certain molecules increase in concentrations at higher levels in the food
chain
- heavy metals like mercury and some persistent organic pollutants (POPs) undergo
biomagnification
- when consumers eat something from the lower trophic level, they ingest all of the pollutants
the organism was carrying but concentrate them into smaller biomass because they are not
metabolized or excreted
Food Chains and Webs
- food chain: one possible pathway of energy flow among trophic levels in an ecosystem
- food web: a compact way of summarizing energy flows and complex trophic interactions that
occur in ecosystems
, Ecology Wrap Up
- there are different levels of ecological study that vary in their scope
- abiotic factors are non-living factors that impact species distribution
• e.g. temperature
- biotic factors are living factors that impact species distribution
• e.g. competition for food
- about 10% of biomass is transferred between tropic levels
- food chains and webs summarize energy flow through an ecosystem
Fitness and Species Interaction
- fitness: the ability to survive and produce viable, fertile offspring
- when species interact ...
• positive (+) → a species benefits
• negative (-) → if a species incurs a fitness cost
• neutral (0) → no effect on fitness
- three key themes
• 1) species interactions may affect the distribution and abundance of a particular species
• 2) species act as agents of natural selection when they interact. this is coevolution → a pattern
of evolution where two species influence each others' adaptations
• 3) the outcome of interactions among species is dynamic and conditional
Competition
- competition is a (-/-) interaction that lowers the fitness of both individuals involved
• the act of competing uses resources, so those resources are not available for foraging, mating
or other activities to increase fitness
- intraspecific competition: between members of the same species
• because intraspecific competition for resources intensifies as a population's density increases,
it is a major cause of density-dependent growth
- interspecific competition: when members of different species use the same limiting resources
Levels of Study (Ecology)
- organismal ecology: individuals interacting with each other and their environment?
• explore the morphological, physiological, and behavioral adaptations that allow organisms to
live in a particular area
• ex: salmon migrate from saltwater to freshwater environments to breed
- population ecology: how and why does population size change over space and time?
• population: a group of individuals of the same species that live in the same area at the same
time
• ex: each salmon (female) produces thousands of eggs. on average, only a few offspring will
survive to return to the same steam to breed
- community ecology: how do species interact, and what are the consequences?
• biological community: a community consists of the species that interact with one another in a
particular area
• asks questions about predation, parasitism, competition, and how species respond to physical
disturbances
• ex: salmon are prey as well as predators
- ecosystem ecology: how does energy flow and how do nutrients cycle through the local
environment?
• the whole area including abiotic and biotic factors
• ex: salmon die and then decompose, releasing nutrients that are used by other organisms
- global ecology: how is the biosphere affected by global changes in nutrient cycling and
climate?
• ex: worldwide populations of salmon are affected by climate change
- conservation biology: the effort to study, preserve, and restore threatened populations,
communities, and ecosystems
Abiotic Factors and Niches
,- no species lives everywhere on Earth
- the suite of conditions a species can tolerate factor into an organism's niche
- abiotic (non-living) factors explain only part of species distributions
Biotic Factors
- biotic ("living") factors-interactions with other organisms limit distributions
- competition
- reproductive requirements
- parasitism
- other interactions
Communities Change Over Time → Ecological Succession
- prairies (good examples)
- long-term effects of fire on a tallgrass prairie community
Trophic interactions can also have extraordinary influence on niche availability and diversity
- trophic: different levels of species (in terms of energy)
How does energy flow through ecosystems?
- primary producer → primary consumer → secondary consumer → tertiary consumer
- energy dissipates as it flows through the system as heat
- nutrients cycle through trophic levels
- each level decomposes to provide nutrients to primary producers
- energy flow model: energy moves through organisms in a form of biomass
- a primary producer (autotroph): an organism that can synthesize its own food from inorganic
sources
- consumers eat living organisms
,• primary consumers eat primary producers
• secondary consumers eat primary consumers
• tertiary consumers eat secondary consumers
- decomposers, or detritivores, feed on detritus, the waste products, or dead remains of other
organisms
- organisms that obtain energy from the same type of source occupy the same trophic
("feeding") level
The Pyramid of Productivity
- all ecosystems share a characteristic pattern
• the total biomass produced per year is greatest at the lowest trophic level and declines at
higher levels
- this pattern occurs because most of the energy consumed is used for growth and reproduction
• the amount of biomass produced at each subsequent trophic level must be less than the
amount at the previous level (10% rule)
Biomagnification
- biomagnification: certain molecules increase in concentrations at higher levels in the food
chain
- heavy metals like mercury and some persistent organic pollutants (POPs) undergo
biomagnification
- when consumers eat something from the lower trophic level, they ingest all of the pollutants
the organism was carrying but concentrate them into smaller biomass because they are not
metabolized or excreted
Food Chains and Webs
- food chain: one possible pathway of energy flow among trophic levels in an ecosystem
- food web: a compact way of summarizing energy flows and complex trophic interactions that
occur in ecosystems
, Ecology Wrap Up
- there are different levels of ecological study that vary in their scope
- abiotic factors are non-living factors that impact species distribution
• e.g. temperature
- biotic factors are living factors that impact species distribution
• e.g. competition for food
- about 10% of biomass is transferred between tropic levels
- food chains and webs summarize energy flow through an ecosystem
Fitness and Species Interaction
- fitness: the ability to survive and produce viable, fertile offspring
- when species interact ...
• positive (+) → a species benefits
• negative (-) → if a species incurs a fitness cost
• neutral (0) → no effect on fitness
- three key themes
• 1) species interactions may affect the distribution and abundance of a particular species
• 2) species act as agents of natural selection when they interact. this is coevolution → a pattern
of evolution where two species influence each others' adaptations
• 3) the outcome of interactions among species is dynamic and conditional
Competition
- competition is a (-/-) interaction that lowers the fitness of both individuals involved
• the act of competing uses resources, so those resources are not available for foraging, mating
or other activities to increase fitness
- intraspecific competition: between members of the same species
• because intraspecific competition for resources intensifies as a population's density increases,
it is a major cause of density-dependent growth
- interspecific competition: when members of different species use the same limiting resources
