C4.1 Flashcards
Population and Communities
1
Q
Sampling Population Sizes
What is population?
A
- A population is defined as “interacting groups of organisms of the same species living in an area.”
- Need to be the same species - which means that they have to be organisms that are able to succesfully interbreed.
2
Q
Sampling Population Sizes
What is meant by Population size?
A
- The number/ estimated number of individuals of the same species living in that area AT THAT PARTICULAR TIME.
- Constantly fluctuating, even stable populations fluctuate according to births, deaths and individuals enterting and leaving.
3
Q
Sampling Population Sizes
What is a Random Sample?
A
- a sample when the zone/area that it is taken from are randomly chosen, rather than using a predictable pattern.
- systematic sampling –> samples taken along a set grid at regular intervals (or along a transect)
4
Q
Sampling Population Sizes
What is a sampling error?
A
- The difference between the estimated population size (from the sample) and the actual real population size is the sampling error.
- Used to predict the likely degree of error.
5
Q
Sampling Population Sizes
What is Quadrat Sampling?
A
- For sessile (unmovable) organsisms, quadrats are an effective way to complete a random sample.
- A quadrat is a square of particular dimesntion that can be made of metal, plastic or wood.
- Placed in a random location in the area and organisms that lie completely inside the quadrant are counted.
6
Q
Sampling Population Sizes
What does standard deviation tell us?
A
- Gives an indication of how spread out a data set it.
- Small standard deviation –> most of the data is close to the mean.
- Large standard deviation –> data is very spread out.
7
Q
Sampling Population Sizes
When do we Capture - Recapture?
A
- capture as many organisms as possible and MARK THEM.
- Then recapture and see how many are marked.
- If most are marked –> suggests a small population.
- If most are unmarked –> suggests a larger population.
8
Q
Sampling Population Sizes
What is the Lincoln Index?
A
- The formula for the Lincoln Index which uses data gathered from capture-recapture data to approximate a sample siz.e
9
Q
Sampling Population Sizes
What is the Carrying Capacity
A
- A population is defined by the ogranisms in one area and most areas/ habitats have a finite number of resources such as food, water and shelter.
- These limited number of resources, an area cannot meet the needs of an unlimited number of organisms.
- The carrying capacity is the maximum number of organisms that an environment can consistently meet the need sof.
- If the population goes above the carrying capacity the death rate will increase until it goes below it and eventually will stablise around it.
10
Q
Population Growth Patterns
What is a Limiting Factor?
A
- Any aspect or event in a habitat that prevents a population from continuing to grow larger is a limiting factor.
- Limits the population size.
11
Q
Population Growth Patterns
Difference between Density dependent and density independent factors?
A
Chance events can occur that reduce a population’s size.
- DENSITY INDEPENDENT: if factors are unrelated to the population’s size or crowdesness in the habitat.
- DENSITY DEPENDENT: If a factor is much more significant in a crowded population and become more problematic as the population increases.
12
Q
Population Growth Patterns
Types of Density-Dependent factors
A
They are significant in larger populations –> as they bring them back to a smaller size where they have less impact. (NEGATIVE FEEDBACK PROCESS.)
- More predators
- Competition for food, water, space.
- Faster spread of pathogens and parasites.
13
Q
Population Growth Patterns
Stages in Logistic.
Population Growth:
A
- As populations grow from its initial development in the area, it will go from having the resources to grow very rapidly to eventually stabalizing at the carrying capacity.
- When graphed –> sigmoid curve. (S-shape)
14
Q
Population Growth Patterns
Stages in Logistic.
Population Growth:
EXPONETIAL PHASE
A
(the steep slop upwards)
- There is ample resources for very rapid growth when a small number of organisms find an uninhabited area.
- Population begins to double, because each generation is larger –> population grows at accelerating rate.
15
Q
Population Growth Patterns
Stages in Logistic.
Population Growth:
TRANSITIONAL PHASE
A
(the bend in the S)
- Population is now large enough so that resources have begun to be more limited, thus rate of growth slows.
- There is still a continued growth/ increase in pop size, but considerably slower pace as competition, predators and disease limit how many offspring can thrive.
16
Q
Population Growth Patterns
Stages in Logistic.
Population Growth:
PLATEAU PHASE
A
(straight part below carrying capacity)
- Population size evetually stablises at a sustainable size for that area (CARRYING CAPACITY)
- May still be some leaps above, but in general, a plateau at the carrying capacity will be established.
17
Q
Community Relationships
What is a community?
A
- Comprised of all the populations in an area including plants, animals, fungi and bacteria.
- The viotic factors of a habitat.
- Emphasoses that the population are interacting with one another.
- Interactions include feeding relationships, competition and symbiotic relationships.
18
Q
Community Relationships
What is a limiting factor for a community?
A
- This is something that in finite availability that is needed for survival for many individuals in a community.
- They often give rise to competition –> can be between members of the same species or between different spcies.
19
Q
Community Relationships
What is herbivory?
A
- An interspecific relationship.
- Involves primary consumers feeding on producers –> often does not kill the producer.
- Herbivores grazing can even help the producer to regenerate –> however, there are isntances when it does cause harm to the producer and small plants can be killed by herbivores.
20
Q
Community Relationships
What is predation?
A
- An interspecific relationship that involves one consumer species (predator) killing and eating another consumer species (prey).
- This relationship involes the INGESTION of the organism.
- Plays an important role in ecosystems –> stability as apex predators can maintain populations around the carrying capacity.
21
Q
Community Relationships
What is mutualism?
A
A TYPE of symbiotic relationship.
- In symbiotic –> two different species have an ongoing close assocation that provides a benefit to one of them.
- In Mutualistic –> both species benefit from the relationship. Often they can be two differnt types of roganisms so that each has different capabilites they can offer.
22
Q
Community Relationships
What is Parasitism?
A
A TYPE of a symbiotic relationship as it involes ongoing asscociation between two different species whereby one benefits.
- The parasit benefits from the relationship but it comes at a harm to the host organism.
- Parasite does not ingest/ eat the host, but often does obtain food from them –> living inside them. sucking blood from them –> makes a parsite DISTINCT FROM A PREDATOR.
23
Q
Community Relationships
What is pathogenicity?
A
- A pathogen lives inside another spcies but in doing so causes disease to the host.
- Not an ongoing relationship as the disease will either kill the host or prompt an immune response in the host that will kill the pathogen.
- Pathogenicity refers to the disease-casuing quality of an organisms.
24
Q
Community Relationships
What is an endemic species?
A
- Naturally found in that area, a population in its natural habitat.
- As it is there natural habitat –> there are density dependent factors (prey availability and predators) that maintain the population size around a carrying capacity.
25
# Community Relationships
What is an invasive species?
- A species that has moved into a non-natural habitat.
- Oftern, alien species lacks the prey sources to survive and quickly dies off, however there are times where they can utilize the new prey opportunities AND do not have a natural predator in that environment.
- Thus, can rapidly reproduce and outcomplete endemic species.
- When they are successfully surviving in a non-native environment --> called INVASIVE SPEICES.
- They have the potential to do much damage to stable ecosystemts --> modern threat due to human transport of them.
26
# Community Relationships
Intraspecific vs Interspecific
Intraspecific: Between members of the same species in a shared habitat. (COOPERATION AND COMPETITION.
Interspecific: Between different speices living in the same community. (COMPETITION, PREDATION, SYMBTIOIC RELATIONSHIPS AND PATHOGENICITY.)
27
# Community Relationships
Types of Cooperation and Competition
Both Cooperation and Competition exist between/ within species.
WITHING COOP: huddling behaviour, hunting in groups, fish moving in schools, parental care of offspring.
BETWEEN COOP: Mutualistic relationships, such as pollination and the algae in coral polyps.
WITHIN COMPET: Competition for resources, light, mates, space. Gives rise to reaching a carrying capacity.
BETWEEN COMPET: Prey, habitat.
28
# Community Relationships
Inavise specie's impact.
- Two species can not occupy the same niche --> gives rise to niche partioning which involves both species occupying a small realized nich.
- Invasive species enter an established niche --> can thrive without predators.
- Due to competitive exclusion principle, the endemic species will not be able to continue to survive well --> results in the complete loss of the endemic species as the invasive species consumes the niche.
29
# Chi Square Test of Association
Species Association
- If two species have an interspecific relationship --> it is expetcted that their distribution would be in some way impacted by the other.
- If mutualistic/ predation relationship --> expect to find them close together geographically.
- If competitive relationship --> then competitive exclusion predicts they will tend to be away from each other.
- Species with no relationship --> have no pattern together.
30
# Chi Square Test of Association
Using quadrats for association
- Random quadrats can be used to test for associtation.
- If two species have positive association --> expect to find both OR neither in quadrats.
- If two species have negataive (competitive) association --> expect to find them in different quadrats.
- If no relationship to one another --> no distinct pattern -- sometimes just coexist --> random.
31
# Chi Square Test of Association
Null Hypothesis
- A test to determine whether the relationship is statistically significant.
- FIRST HYPOTHESIS: Null: There is NOT a significant trend in the data, the points are random and any pattern is only by chance.
"The two species are distributed independently."
(no relationship between them, co-existence/ seperation is random.)
32
# Chi Square Test of Association
Alternative Hypothesis
- Experimental hypothesis --> propse that there is a relationship.
- The two species are associated.
33
# Chi Square Test of Association
Experiment vs Obervation
Observational: does not involve manipulation of indpendent and dependent variables.
- Harder to determine the exact cause and role of each variable.
- Can be effective for long term research and are often more authentic to the ecosystem's complexity.
Experimental: Has to manipulate a variable (the independent variable) and then investigate the impact of that variable that they manipualted (the data on the impact is the depedent variable) --> comparing to a control group without the independent variable.
- Considerably stronger and more reliable --> better able to really conclude one thing caused another.
34
# Predation
What are antibiotics and how do they effect communities?
- An example of secondary metabolites (something that is made not for life functions, but to release into the environment.)
- An example of allelopahty whereby one organism releases a chemical that negatively impacts another.
- In antibiotics, the chemical released kills/inhibits growth of nearby bacteria.
35
# Predation
What is allelopathy and how does it effect communities?
- The release of chemicals (secondary metabolities) into the environment that impacts another organism.
- Often harmful impact, to then provide some sort of competitive advantage.
EXAMPLES: chemicals released into the soil that inhibit seed germination or nutrient absorption. As well as antibiotics, which are examples of allelopathy that effects microorganisms.
36
# Predation
What is cyclical oscillation for predators and prey?
- An increase in prey leads to an increase in predator population (more food)
- An increase in predator populations would decrease the prey population (more death)
- The decrease in prey will decrease the predator population due to lack of food.
- The decrease in predator population will give the chance for the prey to increase. --> RESTARTS THE CYCLICAL OSCILLATION PATTERN/ CYCLE.
Predators and prey both act as DENSITY DEPENDENT factors to each other --> their dependence creates this cycle.
37
# Predation
Difference between top-down and bottom-up control of populations.
Top-Down Control: higher trophic levels impact the population of lower ones (more predators --> less prey)
(negative feedback loop)
Bottom-Up control: lower trophic levels impact the population of higher ones (more prey --> more predators)
(positive feedback loop).
38
# Predation
Secondary metabolite vs primary metabolite.
PRIMARY METABOLITES: molecules that are necessary for the basic functions of life. Include intermediates in pathways and the end products needed, as they are necessary for life, they are usually shared between all organisms.
SECONDARY METABOLITES: only made by certain organisms to obtain food or avoid predation.
They are usually released into the environment and include toxins that negatively impact other organisms. EG: antiobtics and allelopathy.
