4 Flashcards
Ecology
The branch of biology that concerns interactions between organisms and their environments
Levels of biological organization
organism, population, community, ecosystem, biosphere.
Two principal pattern-based questions are
Where do organisms live?
How common or rare are they?
Two mechanistic questions
What factors determine the distribution of a species?
What factors determine the abundance of a species?
_________ patterns may be characterized
at a variety of spatial scales.
Distribution
Range sizes
Few species are widespread (and common); most species have small ranges (and are rare)
nonliving chemical and physical properties of an individual’s environment (e.g., temperature, light, water, nutrient availability, etc.)
abiotic components
all of the organisms that are part of an individual’s environment (e.g., predators, prey, competitors, mutualists)
Biotic compnets
Both abiotic and biotic factors may influence the ______ and _______ of a given species
distribution, abundance
Local factors, such as topography, proximity to water bodies, and etc., superimpose their effects on the climate of a terrestrial region to produce ___________ (e.g., weather)
Local abiotic conditions
__________ is the study of populations in relation to environment, including environmental influences on density and distribution, age structure, and population size
Population ecology
_____ is the number of individuals per unit area or volume
Density
______is the pattern of spacing among individuals within the boundaries of the population
Dispersion
______ is the influx of new individuals from other areas
Immigration
______ is the movement of individuals out of a population
Emigration
Environmental and social factors influence spacing of individuals in a population
patterns of dispersion
In a _____ dispersion, individuals aggregate in patches. This may be influenced by resource availability and behavior
clumped
A ______ dispersion is one in which individuals are evenly distributed. It may be influenced by social interactions such as territorially.
uniform
In a ______ dispersion, the position of each individual is independent of other individuals. It occurs in the absence of strong attractions or repulsions
Random
_________ is the study of the vital statistics of a population and how they change over time
Demography
Death rates and birth rates are of particular interest to _______.
demographers
A ________ is a graphic way of representing the data in a life table.
survivorship curve
What type of Survivorship curve is “low death rates during early and middle life, then an increase among older age groups”?
Type I
What type of Survivorship curve is “the death rate is constant over the organism’s life span”?
Type II
What type of Survivorship curve is”high death rates for the young, then a slower death rate for survivors”?
Type III
An organism’s ______ comprises the traits that affect its schedule of reproduction and survival
life history
List the life history traits
The age at which reproduction begins.
Survivorship to reproductive age.
How often the organism reproduces.
How many offspring are produced during each reproductive cycle.
Species that exhibit ______ or _______ reproduction, reproduce once and die (all-in)
semelparity, or boom or bust
Species that exhibit _______ or ________ reproduction, produce offspring over multiple years (bet hedging)
iteroparity, or repeated
Variable or unpredictable environments likely favor ________ reproduction, while more stable, predictable environments may favor ______ reproduction
boom or bust, repeated
The ___________ describes population growth in an idealized, unlimited environment
exponential model
It is useful to study population growth in an _________.
________ help us understand the capacity of species to increase and the conditions that may facilitate this growth.
Idealized situations
This is the equation for what? Growth rate = B + I - D + E
Per Capita rate of increase. If immigration and emigration are ignored, a population’s growth rate (per capita increase) equals birth rate + immigration minus (-) death rate + emigration.
______________ occurs when the birth rate equals the death rate
Zero population growth
ΔN/ΔT=rN
Continuous population growth equation. where N = population size, t = time, and r = per capita rate of increase = birth – death
_____________ is population increase under idealized conditions
Under these conditions, the rate of reproduction is at its maximum, called the ___________.
Exponential population growth, intrinsic rate of increase, dn/dt=(Rmax)N
The ____________ describes how a population grows more slowly as it nears its carrying capacity
logistic growth model.
Exponential growth cannot be sustained for long in any population.
A more realistic population model limits growth by incorporating carrying capacity.
________ is the maximum population size the environment can support
Carrying capacity (K)
In the ___________ model, the per capita rate of increase declines as carrying capacity is reached
logistic population growth
(dn/dt)=rN [1-(N/K)]
The logistic growth model. We construct the logistic model by starting with the exponential model and adding an expression that reduces per capita rate of increase as N approaches K
The logistic model fits few real populations but is useful for estimating possible growth
.
_________ the populations that co-occur in a given place at a given time.
Community
Important static properties of a community:
Species richness = the number of species.
Relative abundance = relative commonness vs. rarity of species
Species diversity = an integrated measurement of species richness plus relative abundance.
Community Ecologists study communities by asking:
What ecological and evolutionary processes organize and structure communities (e.g., what types of species are present and what types of interactions exist among species)?
Why do communities vary in species composition, species diversity, and other aspects of community organization and structure?
Gleason’s “individualistic” hypothesis
Species occur in a givenarea because they share similar abiotic (e.g., habitat) requirements
Clements’ “integrated” hypothesis
Species are locked into communities through mandatory biotic interactions.
Communities viewed as “super organisms”.
Gleason’s “individualistic” hypothesis for community organization has received the most support from field-based studies.
Nevertheless, species interactions are important components of community dynamics.
.
Mutualism
(+/+) Traits of species often evolve as a result of interspecific interactions. One species may evolve traits that benefit that species in its interactions with another species. Coevolution occurs when two species reciprocally evolve in response to one another. Biology symbiosis that is beneficial to both organisms involved.
Pollination
(+/+) Usually a type of mutualism. Convey pollen to or deposit pollen on and so allow fertilization.
Frugivory & Seed Dispersal
(+/+) (Usually a type of mutualism)
Predation
(+/-) Striking adaptations often characterize predators and their prey
Herbivory
(+/-) Feeding (sometimes predation)
by animals on plants
Parasitism
(+/-) Parasites derive nourishment from their hosts, whether they live inside their hosts (endoparasites) or feed from the external surfaces of their hosts (ectoparasites)
Parasitoidism
(+/-) Parasitoids lay eggs on living hosts and their larvae eventually kill the host
Commensalism
(+/0) E.g., mites hitching a ride on a beetle
Amensalism
(-/0) Common, but not considered an important process structuring communities;
e.g., elephant stepping on ants
Neutralism
(0/0) Common, but not considered an important process structuring communities;
e.g., hummingbirds and earthworms (they never interact with one another)
Competition
(-/-) Organisms often compete for limiting resources.
E.g., smaller plants are shaded by larger plants
Competition among members of the same or different species for an important, limiting resource
Intraspecific Competition
one species denies another access to a resource simply by consuming it first
Exploitation Competition
one species actively inhibits the foraging, survival, or reproduction of the other species
Interference Competition
one species denies another access simply by getting there first.
Preemptive Competition
Name 2 consequences of competition
Coexistence and exclusion of one species.
an organism’s “address” (habitat) and “occupation” in the presence
of biotic enemies
Realized niche. competition(-/-)
Heterotrophs consist of
primary consumer, secondary consumer, tertiary sonsumer, quaternary sonsumer, omnivores, detritivores, scavengers and decomposte.
primary produces =
autotrophs
The length of food chains is rarely > ________ trophic levels long
4 or 5. The main reason follows from the Laws of Thermodynamics:
Energy transfer between trophic levels is only ~10% efficient
Who said “portrayed ecosystem as a pyramid of energy. Less energy gets to the top because organisms expend energy”?
Raymond Lindeman (1942) -
Diversity-Productivity Relationship
Current-day processes that create a latitudinal gradient in energy availability appear to contribute to the latitudinal gradient in diversity
.
When 2 habitats of the have the same slope but different magnitudes. There is a point called________ where the poor habitat will be equally as attractive as the rich habitat.
The ideal free distribution.
_____________ is built upon the idea of time constraint (foraging theory). 24 hours is divided into time spent unrelated to eating and eating related activates.
Classic predation theory
__________ is all activities up to the point of spotting the prey. This is (affected by prey density, searching speed, refined search image, biophysical limitations)
Search time
_______ is all activities from spotting to digesting the prey
Handling time.
Tmax=Ts+Th
The math of predation. Ts= total search time per day. Th=total handling time per day.
per-predator capture rate
n/Ts. n=number of victims captured. Ts=time spent searching.
(n/t)= [(αV)/(1+αhV)]
Capture rate=(n/t). n=number of victims captured. T=time. V=victim density. α=capture efficiency. H=handling time
The larger the prey, The _____ handling time
Greater
Three Functional Responses
(of predators with respect to prey abundance)
What function responses is “Consumption per predator depends only on capture efficiency: no handling time constraint.”? (n/t)=αV
Holling type I (Filter Feeders)
What function responses is “Predator is constrained by handling time.”? (n/t)= [(αV)/(1+αhV)]
Holling type II (Predator with significant handling time limitations)
What function responses is “Predator is constrained by handling time but also changes foraging behavior when victim density is low.”? (n/t)= [(αV)^2 / 1+(αhV)^2]
Holling type III (Predator who pays less attention to victims at low density)
The dynamics of predator prey systems are often quite complex and dependent on ________ and __________.
foraging mechanics and constraints.
What are the possible outcomes of predator-prey interactions
1 The predator goes extinct. 2 Both species go extinct. 3 Predator and prey coexist in stable ratios. 4 Predator prey cycle. (prey boom->predator boom->prey bust->Predator bust->repeat)
Population dynamics: Predators(P) dP/dt=
dP/dt = Victim consumption rate * Victim -> Predator conversion efficiency - Predator death rate
Population dynamics: Victims(V): dV/dt=
Victim renewal rate – Victim consumption rate
The ________________ illustrates how the variety of outcomes in Predator-Prey systems can come about
Rosenzweig-MacArthur Model
The Rosenzweig-MacArthur Model: #1
Both predator and prey can go extinct if the predator is too efficient capturing prey (or the prey is too good at getting away
The Rosenzweig-MacArthur Model: #2
The predator can go extinct while the prey survives, if the predator is not efficient enough: even with the prey is at carrying capacity, the predator cannot capture enough prey to persist.
The Rosenzweig-MacArthur Model: #3
With the capture efficiency in balance, predator and prey can coexist.
a) coexistence without cyclical dynamics, if the predator is relatively inefficient and prey remains close to carrying capacity.
b) coexistence with predator-prey cycles, if the predators are more efficient and regularly bring victim densities down below the level that predators need to maintain their population size.
