Podcast
Questions and Answers
In Borneo in the 1950s, the use of DDT to combat malaria mosquitoes resulted in unforeseen consequences due to its nature as a:
In Borneo in the 1950s, the use of DDT to combat malaria mosquitoes resulted in unforeseen consequences due to its nature as a:
- Selective insecticide targeting only mosquitoes.
- Non-selective insecticide affecting various organisms. (correct)
- Biodegradable compound harmless to other species.
- Mosquito repellent, not an insecticide.
Geckos in Borneo were directly targeted by DDT spraying to reduce their population.
Geckos in Borneo were directly targeted by DDT spraying to reduce their population.
False (B)
What was the unintended consequence of the reduction in the gecko population in Borneo after DDT spraying?
What was the unintended consequence of the reduction in the gecko population in Borneo after DDT spraying?
A rise in the rat population and subsequent spread of diseases.
The houses in Borneo had roofs made of ______, which were eaten by caterpillars.
The houses in Borneo had roofs made of ______, which were eaten by caterpillars.
Match the term with its correct description:
Match the term with its correct description:
What term describes the interactions between different species for a resource?
What term describes the interactions between different species for a resource?
Competitive exclusion suggests that two species can coexist permanently even if they have identical niches.
Competitive exclusion suggests that two species can coexist permanently even if they have identical niches.
What mechanisms do similar species use to coexist without direct competition?
What mechanisms do similar species use to coexist without direct competition?
The ______ niche refers to the set of conditions under which a species actually lives, taking into account interspecific competition.
The ______ niche refers to the set of conditions under which a species actually lives, taking into account interspecific competition.
Match the term to the appropriate selection:
Match the term to the appropriate selection:
What is character displacement?
What is character displacement?
Exploitation refers only to predation, where one species kills and eats another.
Exploitation refers only to predation, where one species kills and eats another.
Give one example of adaptation to predation.
Give one example of adaptation to predation.
[Blank] is a type of mimicry in which a harmless species evolves to imitate the warning signals of a harmful one.
[Blank] is a type of mimicry in which a harmless species evolves to imitate the warning signals of a harmful one.
Match the community interaction to its definition.
Match the community interaction to its definition.
What is a general term referring to a +/+ or +/0 interaction in which at least one species benefits and neither is harmed?
What is a general term referring to a +/+ or +/0 interaction in which at least one species benefits and neither is harmed?
In commensalism, both species involved benefit each other.
In commensalism, both species involved benefit each other.
What is the term for a +/+ ecological interaction?
What is the term for a +/+ ecological interaction?
In a ______ relationship organisms are helped but are not necessary for their survival.
In a ______ relationship organisms are helped but are not necessary for their survival.
Match the community interaction to its correct description:
Match the community interaction to its correct description:
Which is NOT a way to characterize the composition of a community?
Which is NOT a way to characterize the composition of a community?
Species richness alone fully describes species diversity.
Species richness alone fully describes species diversity.
Name two components of species diversity.
Name two components of species diversity.
The proportion each species represents of all individuals in the community is known as ______ abundance.
The proportion each species represents of all individuals in the community is known as ______ abundance.
Which of the following statements about more diverse communities are TRUE?
Which of the following statements about more diverse communities are TRUE?
Communities with low diversity tend to be more resistant to invasive species.
Communities with low diversity tend to be more resistant to invasive species.
What is meant by trophic structure?
What is meant by trophic structure?
An organism with similar trophic relationships are grouped into a ______ group.
An organism with similar trophic relationships are grouped into a ______ group.
Match the following trophic levels with their descriptions:
Match the following trophic levels with their descriptions:
Why are food chains limited in their number of links?
Why are food chains limited in their number of links?
The energetic hypothesis says each food chain in a food web tend to be long because energy transfer is efficient
The energetic hypothesis says each food chain in a food web tend to be long because energy transfer is efficient
How much mass is converted into the next trophic level?
How much mass is converted into the next trophic level?
There fore, 100kg of organic material can support ______ kg. of herbivore biomass.
There fore, 100kg of organic material can support ______ kg. of herbivore biomass.
Match the following terms:
Match the following terms:
A species that is most abundant or has the highest biomass is called:
A species that is most abundant or has the highest biomass is called:
Top-Down and Bottom-Up models control the abundance of species within a community.
Top-Down and Bottom-Up models control the abundance of species within a community.
Are keystone species necessarily abundant in a community? (yes/no)
Are keystone species necessarily abundant in a community? (yes/no)
Top-Down models are also known as ______ cascade models.
Top-Down models are also known as ______ cascade models.
Match the following definition with the term:
Match the following definition with the term:
In Borneo in the 1950s, the spraying of DDT to combat malaria inadvertently led to a series of ecological consequences. Which of the following was NOT a direct result of this action?
In Borneo in the 1950s, the spraying of DDT to combat malaria inadvertently led to a series of ecological consequences. Which of the following was NOT a direct result of this action?
A community with higher species diversity is generally less resistant to invasive species.
A community with higher species diversity is generally less resistant to invasive species.
Define 'niche' in the context of community ecology.
Define 'niche' in the context of community ecology.
The concept that two species competing for the exact same limiting resources cannot coexist is known as the principle of ______.
The concept that two species competing for the exact same limiting resources cannot coexist is known as the principle of ______.
Match the following ecological interactions with their correct descriptions:
Match the following ecological interactions with their correct descriptions:
Character displacement is best described as:
Character displacement is best described as:
Which of the following is the most accurate description of a 'keystone species'?
Which of the following is the most accurate description of a 'keystone species'?
In a bottom-up control model, predators primarily limit nutrient levels.
In a bottom-up control model, predators primarily limit nutrient levels.
Which of the following scenarios exemplifies resource partitioning?
Which of the following scenarios exemplifies resource partitioning?
What is the energetic hypothesis?
What is the energetic hypothesis?
Flashcards
Biological Community
Biological Community
A biological community is a group of populations of different species that live close enough to interact.
Niche
Niche
An ecological role of a species in a community.
Competitive Exclusion
Competitive Exclusion
Two species cannot coexist in the same place if they are competing for the same limiting resources.
Resource Partitioning
Resource Partitioning
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Fundamental Niche
Fundamental Niche
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Realized Niche
Realized Niche
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Character Displacement
Character Displacement
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Exploitation
Exploitation
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Predation
Predation
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Cryptic Coloration
Cryptic Coloration
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Aposematic Coloration
Aposematic Coloration
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Batesian Mimicry
Batesian Mimicry
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Herbivory
Herbivory
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Parasitism
Parasitism
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Positive Interaction
Positive Interaction
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Mutualism
Mutualism
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Commensalism
Commensalism
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Species Diversity
Species Diversity
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Species Richness
Species Richness
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Relative Abundance
Relative Abundance
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Trophic Structure
Trophic Structure
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Dominant Species
Dominant Species
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Keystone Species
Keystone Species
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Ecosystem engineers
Ecosystem engineers
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Bottom-up Model
Bottom-up Model
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Top-Down Model
Top-Down Model
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Study Notes
- The lecture is the last class of Bio102.
Course Information
- Bio200 - Cell Bio
- Bio201 - Biochem
- Bio203 - Genetics
- Bio215 – Microbiology
- Bio230 – Ecology
- Bio160/161 – Human Anatomy & Physiology
- Che200/201 – Organic Chemistry
Course Grading Policies
- Closed book average >50% is required, calculated from the midterm, final, and lab quiz grade.
- Lab grade also needs to be >50%.
- Failing to submit 3 lab assignments or not attending the lab results in failing the lab component.
Kelp Forest Communities
- Kelp forest communities can turn into urchin barrens.
- Further learning is available at https://yoteachapp.com/Bio102CV, password: genes
Community Ecology Example: Borneo
- In the 1950s, malaria was rampant in Borneo.
- DDT was sprayed to kill the mosquitoes, which lowered malaria rates.
- DDT is a non-selective insecticide that kills more than just mosquitoes.
- Geckos, which are insectivorous reptiles, ate DDT-affected insects and became sick.
- Cats ate the sick geckos and died due to concentrated DDT in their bodies.
- The rat population exploded.
- The level of disease (plague and typhoid) spread by rats and their fleas began to explode.
- People were no longer happy.
- A decision was made to parachute 14,000 cats into Borneo.
- Houses in Borneo have thatched roofs.
- Caterpillars eat the thatch.
- Geckos, which had been killed by DDT or eaten by cats, normally keep the caterpillars under control.
- Parasitic wasps also controlled the caterpillars, but they were killed by DDT.
- The caterpillar population grew and destroyed the thatched roofs.
- All collapsed until the cats landed.
- Everything is connected, which relates to community ecology.
Definitions
- Biological Community: A group of populations of different species that live close enough to interact.
- Habitat: A species' location in the community; its "address."
- Niche: A species' ecological role or "job."
Competition in Community Structure
- Interspecific interactions occur between species for a resource and include:
- Competition
- Predation
- Herbivory
- Parasitism
- Mutualism
- Commensalism
Competitive Exclusion
- Two species competing for the same limiting resources cannot coexist in the same place.
Ecological Niches and Natural Selection
- Competition can lead to evolutionary change in populations, focusing on the ecological niche of the organism.
- Two species cannot coexist permanently if their niches are identical.
- Resource Partitioning: Similar species coexist by avoiding competition and having significant differences in their niches.
- Fundamental niche: Where a species could live.
- Realized niche: Where a species actually lives due to interspecific competition.
- Interspecific competition can influence a species' niche.
Character Displacement
- Evolution of differences in morphology and resource use as a result of competition is character displacement.
- An example is seen in three-spine sticklebacks, with deep-bodied benthic forms adapted for bottom feeding and slender limnetic forms better for feeding on zooplankton.
Ecological Niche Examples
- Different bumblebee species prefer different flower corolla lengths.
- Sparrows only eat berries on bushes because of mice on the ground.
- The introduction of the American mink caused the native European mink to increase in size and the introduced mink to decrease.
Resource Partitioning
- Slight variations in niches enable similar species to coexist.
- Learn more at https://yoteachapp.com/Bio102CV, password: genes
Fundamental vs Realized Niche
- Therealized niche is determined by competitors.
- More information at https://yoteachapp.com/Bio102CV, password: genes
Exploitation
- It is a general term for any + / - interaction in which one species benefits at the expense of the other.
- Includes:
- Predation
- Herbivory
- Parasitism
Predation in Community Structure
- Where one species (the predator) kills and eats another (the prey).
- +/- interaction
- Adaptations to predation include:
- Cryptic coloration
- Aposymatic coloration
- Batesian Mimicry
- Protection (shell, spines, and quills)
Herbivory
- One species eats parts of a plant.
- +/- interaction
- Herbivores may have adaptations to distinguish toxic and non-toxic plants and have specialized digestive systems or teeth.
- Adaptations to herbivory include chemical toxins, spines, and thorns.
Parasitism
- It is a +/- interaction.
- A parasite derives nourishment from its host, which is harmed.
- Endoparasites and ectoparasites exist.
Positive Interactions
- General term referring to a +/+ or +/0 interaction in which at least one species benefits and neither is harmed.
- Includes:
- Mutualism: +/+ interaction; benefits both species and can be obligate or facultative.
- Commensalism: +/0 interaction; benefits one species with no effect on the other.
Exploitation vs Positive-Type Interaction
- A mother bear caring for her cub does not demonstrate an exploitation-type interaction or positive-type interaction.
Community Structure
- Interactions depend on species composition.
- Characterizing composition can happen in different ways.
- Communities have species that exert control.
- To learn about:
- Species Diversity
- Diversity and Community Stability
- Trophic Structure - Species with Large Impact
Species Diversity
- The variety of different organisms that make up a community.
- It contains two components:
- Species richness: The total number of different species.
- Relative abundance: The proportion each species represents of the total individuals in the community.
- Communities can have same species richness, but relative aboundance differs.
Diversity and Community Stability
- Ecologists manipulate diversity to study potential benefits.
- Communities with higher diversity are:
- more productive
- more stable
- better able to recover from stresses
- more resistant to invasive species
- Study plots at the Cedar Creek Natural History Area used for experiments manipulating plant diversity.
Trophic Structure
- Focuses on feeding relationships between organisms in a community.
- Is a key factor in community dynamics.
Trophic Structure: Food Chains
- Food chains link trophic levels from producers to top carnivores.
Trophic Structure: Food Webs
- Food webs are more realistic, with food chains linked within a community.
- Species with similar trophic relationships are grouped into broad functional groups.
Trophic Structure: Food Chain Length
- Each food chain in a food web is usually a few links long due to inefficient energy transfer.
- Energetic hypothesis attempts to explain food chain length.
- Only about 10% of the energy stored in organic matter in a given trophic level is converted to organic matter in the next.
- A producer level consisting of 100 kg of plant material can support about 10 kg of herbivore biomass.
- Research measuring the number of links was conducted in tree-hole communities in Queensland.
Species with Large Impact: Dominant Species
- Species that are most abundant or have the highest biomass have overt powerful control over distribution/occurrence of other species.
Species with Large Impact: Keystone Species
- Keystone species are not necessarily abundant.
- They exert strong control through their ecological roles or niches.
Species With Large Impact: Ecosystem Engineers
- Ecosystem engineers make physical changes that affect community structure.
Species With Large Impact: Controls
- Bottom-Up and Top-Down Controls determines what controls abundance and biomass.
- The bottom-up model flows from lower to higher trophic levels.
- The top-down model is also known as the trophic cascade model.
- Control comes from trophic level above.
Types of Community Structure
- Questions to consider include:
- What eats what?
- What happens when you remove something?
- How does climate change the interaction?
- More information is available at https://yoteachapp.com/Bio102CV, password: genes
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