Campbell and Reece Chapter 52 Flashcards
Ecology
study of how living organisms and the physical environment interact in an immense and complicated web of relationships
Biotic
interactions among organisms
Abiotic
organisms and non-living, physical environment
Examples of abiotic factors
- Precipitation
- Temperature
- pH
- Wind
- Chemical nutrients
Environmental science
study of human interaction with the environment
Levels of organization
Species < Population < Community < Ecosystem < Landscape < Biosphere
Population
Group consisting of members of the same species that live together in a geographical area
What characterizes populations?
- Population density
- Population dispersion
- Natality/Mortality rates
- Growth rates
- Survivorship
- Age Structure
Populations have _____ than communities
different properties
Population ecology
the number of individuals of a particular species in an area and the dynamics of that population
What do population ecologists study?
- Common processes
- Interactions with environment
- Competition for resources
- Limiting factors
population dynamics
study of changes in populations
What is studied in population dynamics?
- Reproductive success or failure
- Evolution
- Genetics
- Effect on normal communities/ecosystems
Population density
number of individuals of specie per unit of area or volume at a given time (may vary from season to season)
Dispersion
characteristic spacing of species relative to one another
Three types of dispersion
- random
- clumped
- uniform
Random dispersion
occurs when individuals in a population are spaced throughout an area in a manner that is unrelated to the presence of others
Clumped dispersion
concentrated individuals
Uniform dispersion
evenly spaced
Pros of clumped dispersion
- Social animals derive benefits from association
- fish schooling to deter predators
Cons of clumped dispersion
- patchy distribution of resources
- limited seed dispersal or asexual reproduction (plants)
What are changes in population size defined by?
Natality
Mortality
Dispersal
Natality
birth rate
Mortality
death rate
Dispersal
movement of individuals among populations
Immigration
individuals enter population increasing size
emigration
individuals leave population decreasing size
Intrinsic rate of increase
maximum growth rate a population could sustain considering limiting factors
Factors that determine growth rate
- fraction of life span when reproductive
- age where reproduction begins
- number of reproductive periods per lifetime
- number of offspring from each period
Generally, ___ species have __ intrinsic rates while ___ species have ____ intrinsic rates
large-low, small-high
How is intrinsic value displayed?
exponential curve
Carrying capacity (K)
largest population that can be maintained for an indefinite period by a given environment
Logistical population growth
curve is graphed as an “S” curve once limits are reached
two types of limiting factors
density-independent
density-dependent
Density-independent
factor is not altered by population density
Examples of density-independent
Frost, blizzard, hurricane
Density-dependent
factor is altered by population density
Effects of density-dependent
- negative feedback system
- affects large proportion of population
- raises or lowers natality/mortality
Examples of density-dependent
Predation, disease, competition
Competition
interaction among two or more individuals that attempt to use the same essential resource
Examples of resources that lead to competition
Food, water, sunlight
Four types of competition
- intraspecific
- interspecific
- interference competition
- exploitation competition
Intraspecific competition
competition within population
interspecific competition
multiple populations
interference competition (contest)
dominant individuals overtake limited resources of other individuals
Exploitation competition (scramble)
resources are shared so at high population densities none of them obtains enough
Semelparous
species that expend energy in a single, immense reproductive effort
Examples of semelparity
agaves, pacific salmon
Iterparous
exhibit repetitive reproductive cycles
Examples of iteroparity
vertebrates, perennial herbaceous plants, shrubs, trees
How does timing affect iteroparity?
Early- not enough energy for growth
Late- no opportunity for multiple cycles
Fecundity
potential capacity to produce offspring
Fitness
ability of an organism to reproduce successfully
r strategists
high per capita growth rate
specs of r strategists
- Small body size
- Early maturity
- Short life span
- Large broods
- Little parental care
- Found in variable, opportunistic habitats
examples of r strategists
mosquitoes and dandelions
k strategists
maximize chances of survival
specs of k strategists
- Do not produce large numbers of offspring
- Large body size
- Slow development
- Long life spans
- Late reproduction
- Low reproductive rate
- Found in stable environments
- Parental care
Life table
shows mortality and survival data of population or cohort
Cohort
a group of individuals at the same age
Survivorship
probability that an individual in a population or cohort will survive to a given age
survivorship curve
logarithm based graph that displays the number of survivors over time
type I survivorship curve
younger cohorts and reproductive ages have highest probability of survival
type II survivorship curve
all cohorts have the same mortality rate
type III survivorship curve
older cohorts have higher chance of survival
landscape
natural heterogeneous landscape consisting of interacting ecosystems that provide a variety of habit patches
Metapopulation
population divided into several populations among which individuals occasionally disperse
Spatial distribution occurs because…
different habitats vary in suitability
source habitats
areas where local reproductive success is greater than mortality
source population effect
greater population densities, surplus individuals relocate
sink habitat
local reproductive success is less than local mortality
sink population effect
no immigration, extinction follows
human population is growing rapidly because…
decrease in mortality rates, due to food production, medicine, and sanitation
highly developed countries characteristics
longer life expectancies, lower birth rates, lower infant mortality rates
moderately developed countries characteristics
medium life expectancies, medium birth rates, medium infant mortality rates
less developed countries characteristics
high birth rates, high infant mortality rates, short life expectancies
replacement-level fertility
number of children a couple must spawn to replace themselves
replacement-level in highly developed countries
2.0
replacement-level in developing countries
2.7
total fertility rate
average number of children born to a woman during a lifetime (2.7 avg)
doubling time
amount of time it would take for a country’s population to double
age structure
number and proportion of people at each age in a population
age structure diagram
number of females and males at each age in a population
population growth momentum
large number of 0 to 14 aged people who will become parents and are a larger group leading to more offspring
relationships between environment and population growth
- rapidly growing population depletes resources
- high desires exhausts resources quickly
people overpopulation
when environment is worsening from too many people
consumption overpopulation
when each individual consumes too large a share of resources
