Population, Community and Ecosystem Ecology Flashcards
group of individuals of the same species that simultaneously occupy the same genera
Population
How and why the population size change over time?
Input: Immigration and Birth
Output: Emigration and Death
The influence of natality, immigration, mortality, and emigration of the population can be expressed as:
Nt = (B-D) + (I-E)
What is density?
The number of individuals per unit area
How do you measure density?
-Count
-Plots
-Indirect indicators/Index of Population Size
-Mark-recapture method
Accurate when there are many sample plots and when the habitat is homogenous
Plots
Number of nests or burrows, signs such as fecal droppings or track
Indirect indicators/index of population size
Involves the marking of a number of individuals in a natural population, returning them to that population, subsequently recapturing some of them as a basis for estimating the size of the population
Mark-recapture method
Mark-recapture method is first used by ______ in studies of marine fishes and by _______ in studies of waterfowl populations
C.J.G. Petersen and F.C. Lincoln
Mark-recapture method is also known as ___________
Lincoln index or Petersen index
What is the formula for mark-recapture method
N = (M*C)/R
what is N = (M*C)/R
N = the estimated number of individuals in the population
M = the number of individuals that are initially captured and marked
C = the total number of individuals captured the second time
R = the number of individuals recaptured
What are the 3 assumptions the mark-recapture method depends on?
- the chance of each individual being caught is equal
- The proportion of unmarked and marked remains constant
- Population size does not increase nor decrease
What are the patterns of distribution?
-Clumped
-Uniform
-Random
Why study population ecology?
Scientific goal: understanding the factors that influence the size of populations
Practical goal: Management of populations
It is the study of factors that affect the growth and decline of populations
Demography
What are examples of demography?
-Age structure
-Generation time
-Sex ratio
it is an age specific summary of the survival pattern of a population
Life tables
It is a group of individuals of the same age
cohort
What are examples of survivorship curves
types I, II, and III
What is type I survivorship curve?
High death rate in post-reproductive years
ex: large mammals
it is the constant mortality rate throughout life span
type II survivorship curve
Very high early mortality but the few survivors then live long and stay reproductive
Type III survivorship curve
limits the population growth based on the size or density of a given population
Density dependent factors
What causes intraspecific competition?
food, mates, nesting sites, etc.
limit population growth based on factors independent of population density.
abiotic factors, chance
Density Independent factors
what are examples of population growth models?
exponential and logistic growth model
This model calculates the maximum rate and displays it as a J-shaped curve (because there are no limits)
Exponential growth model
This model produces an S-shaped curve. As population reaches the carrying capacity, the growth slows and then stops
Logistic growth model
Is the maximum population size that a particular environment can sustain
Carrying capacity
What are examples of reproductive strategies?
r and K specialist
These are equilibrial populations. Those who lives in stable environments and their population fluctuate near to carrying capacity of the ecosystem.
K specialists
What are some characteristics of K specialists?
-long life expectancy
- large body size
-high parental care
-fewer offspring
-Type I or Type II Survivorship curve
These are opportunistic populations. Those individuals which resides in an unstable environment and shows exponential growth pattern
r specialists
Characteristics of r specialists
-can have many offsprings
-short life span
- high mortality among young
-exhibits a J shaped growth curve
-little to no parental care
Formula for growth rate
r = b-d
where
r = growth rate
b = birth rate
d = death rate
What curve leads to a crash in population?
J-curves
Why does J-curves result to a crash in population?
-reduced food
-less places to live and breed
Examples for density depending factors
-competition for resources
-lack of territory
-disease and parasitism
-predation
it is the number of organisms an ecosystem can support indefinitely
Carrying Capacity
it is a group of populations of different species that live in the same area and interact with each other
Community
is the study of how species interact with each other and their environment, including the distribution, structure, and abundance of species.
Community ecology
Community ecology is also known as
synecology
they study the interactions between biotic and abiotic factors such as food webs and competition
Community ecologist
what are examples of interspecific interactions
-competition
-predation
-parasitism
-mutualism
-commensalism
This interaction is detrimental to both species
competition (-/-)
This interaction is beneficial to one species and detrimental to the other
Predation and Parasitism (+/-)
This interaction is beneficial to both species
Mutualism (+/+)
One species benefits from the interaction but the other is unaffected
Commensalism (+/0)
Two species competing for the same limiting resources cannot coexist in the same place
The competitive exclusion principle
who came up with The competitive exclusion principle
Georgy Gause
It is the sum of a species use of the biotic and abiotic resources in its environment
Ecological Niche
Is the ideal conditions in which a species can survive and reproduce
Fundamental Niche
Is the actual conditions a species occupies in the real world, after taking into account competition and other factors
Realized niche
this ecologist studied two barnacle species
Joseph Connell
is a natural selection process that allows species to coexist by dividing resources and avoiding competition
Resource partitioning
Resource partitioning is also known as:
Niche differentiation
is an evolutionary process that occurs when two similar species that share a habitat evolve to reduce competition for resources
Character displacement
groups from an ancestral population evolve into separate species due to a period of geographical separation
allopatric speciation
groups from the same ancestral population evolve into separate species without any geographical separation
sympatric speciation
what are some plant defenses
-physical: thorns and spines
-chemical: poisons
What are some animal defenses
-physical: shells, horns/antlers, teeth
-chemical: poisons, odors
-hiding
-fleeing
-defending themselves against predators
-direction displays
Passive defenses
this type of coloration makes the prey difficult to spot
Cryptic coloration
other term for cryptic coloration
camouflage
this type of coloration serve as a warning to other animals
aposematic coloration
this type of coloration makes animals resemble larger animals
Deceptive coloration
a harmless species imitates the warning signals of harmful species to avoid predators (a type of mimicry)
batesian mimicry
is a type of mimicry in which one or more species develop a similar appearance. Each of the speciesis either poisonous, dangerous, or unpalatable to predators
Mullerian mimicry
these are parasites that live inside the body of a host, can cause severe disease
endoparasites
are parasites that infest the outer surface of their hosts
ectoparasites
a type of parasitism where an organism, called a parasitoid, lives in close association with a host, feeding on the host’s tissues, and eventually killing the host
parasitoidism
is the variety of organisms that make up the community
Species diversity
Components of species diversity
Species richness and Relative abundance
is the total number of different species in the community
Species richness
is the proportion each species represents of the total individuals in the community
relative abundance
diversity can be compared using
diversity indices
these species are the most abundant or collectively have the highest biomass
Dominant species
Dominant species exert powerful control over the _______ and ________ of other species
occurence and distribution
In contrast to dominant species, these type of species are not necessarily abundant in a community
Keystone species
they exert strong control on a community by their ecological roles or niches
keystone species
Organisms that change their physical environment or the availability of resources for other species, which can have a big impact on the surrounding ecosystem.
Foundation species
also called as ecosystem engineers
foundation species
are considered the “base” or “bedrock” of a community, having the greatest influence on its overall structure. They are usually the primary producers: organisms that bring most of the energy into the community.
Foundation species
– Is an event that changes a community
– Removes organisms from a community
– Alters resource availability
disturbance
– Suggests that moderate levels of disturbance can foster higher species diversity than low levels of disturbances
The intermediate disturbance hypothesis
is a process of change in the species make up a community
Ecological succession
– Occurs where no soil exists when succession
begins
– succession starts with a pioneers species colonising bare bed rock or sand
primary succession
species, such as lichen, are adapted to survive in harsh abiotic factors and through their death and decomposition change the abiotic factors to become less harsh and form a thin layer of soil, humus.
Pioneer species
The final stage in a succession is known as the
climax community
- The succesion is disrupted and plants are destroyed
- Succession starts again, but the soil is already created, so it not start from the bare rock seral stage.
Secondary succession
other term for secondary natural succession of pioneer species
autoregeneration
– May facilitate the appearance of later species
by making the environment more favorable
– May inhibit establishment of later species
– May tolerate later species but have no impact on their establishment
Early-arriving species
succession regenerates or creates a community after a ____
disturbance
two types of succession
primary and secondary succession
started by pioneer species
primary succession
started by remaining species
secondary succession
Two key factor correlated with a community’s species diversity
geographic location and size
Two key factors in equitorial-polar gradients of species richness
evolutionary history and climate
species richness is great in the ___
Tropics
is the likely primary cause of latitudinal gradient in biodiversity
climate
two climatic factors correlated with biodiversity
solar energy input and water availability
quantifies the idea that all other factors being equal, the larger the geographic area of a community, the greater the number of species
Species-area curve/relationship
Species-area curve/relationship formula
S = CA^z
where
S=number of species
C=fitted constant
A=area of the island
z=fitted constant
S = CA^z is often presented in linear form:
log(v10) S = log (v10) C + zlog (v10) A
Communities with higher diversity are:
• More productive and more stable
in their productivity
• Better able to withstand and recover from environmental stresses
• More resistant to invasive species, organisms that become established outside their native range
