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Chapter 25 Populations and Ecosystems - Coggle Diagram
Chapter 25 Populations and Ecosystems
Outline
Concepts
Plants in Relationship to Their Habitats
Abiotic Components of the Habitat
Biotic Components of the Habitat
The Structure of Populations
Geographic Distribution
Age Distribution: Demography
R
- and
K
- selection
The Structure of Ecosystems
Physiognomic Structure
Temporal Structure
Species Composition
Trophic levels
Concepts
Ecology
The study of organisms in relationship to all aspects of their surroundings
In plants
Structure
Metabolism
Diversity
Mutation results in new alleles that alter phenotype, then natural selection eliminates those less adapted increasing fitness of the population
Individual vs. Population
Individuals form a population
A population can carry our successful sexual reproduction but an individual cannot
An individual cannot produce enough nectar or pollen to keep one pollinator alive but a population of plants can
A population may be more severely affected by pathogens or other catastrophes than an individual
Populations form communities which comprise ecosystems
populations are rarely stable
Plants in Relationship to their Habitats
Habitats
The set of conditions in which an organism completes its life cycle
Operational Habitat
Aspects of the habitat that definitely affect a plant
Biotic Components of the Habitat
the individual plant
modifies the habitat just by existing within it
beneficial
detrimental
neutral
other plant species
when several individuals of the same or of differing species occur together there is a possibility for interaction between the organisms
Mutualism
an interaction that is beneficial to both organisms
Competition
A situation where two populations do not grow as well together as they do separately due to shared resources
In plants
Light
Soil
Nutrients
Water
The attention of pollinators/seed dispersers
Competitive Exclusion
Whichever species is less adapted is excluded from the ecosystem by competitors
niche
set of conditions best exploited by a species
Second theory postulates that species overlap in their tolerance ranges and each has exclusive use of the portion of the range not used by the other
produces species modification by natural selection
subpopulations classified as ecotypes, which resemble each other so strongly they're obviously the same species but have enough differences to be considered an ecotype
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through time the species diverge until the competition is reduced
Parasitism
Predation
One species benefits and the other is harmed
Herbivory, browsing, and grazing
Commensalism
One species benefits and the other is unharmed
animals
seed dispersal by frugivores
fungi
most relationships are pathogenic
protists
prokaryotes
Abiotic Components of the Habitat
climate
Temperature
The average temperature is not as important as its extremes
often determines growing seasons
Moisture occurs as rain, snow, or hail that provides water but can damage organisms
total amount of precipitation is not as important as seasonal extremes
soil
formed by the breakdown of rock
young soil
variable in the amount of macronutrients and micronutrients available
deficient in Nitrogen
tolerated by pioneer organisms
A Horizon
uppermost layer
zone of leaching
consists of litter and debris
B Horizon
Second layer
zone of desposition
Where materials from A Horizon accumulate
Rich in nutrients
contains humus and clay
C Horizon
Layer beneath B Horizon
composed of parent rock and rock fragments
latitude
At the equator, all days are 12 hours long with no seasonal variation
In areas other than the equator, the amount of light energy that strikes a given area of Earth's surface varies with latitude
altitude
higher altitudes have poor soil and high UV exposure
disturbances
Phenomena that produce a significant, radical change in an ecosystem in a short period of time
have little or no impact on other abiotic factors
Elimination of large numbers of individuals alters species relationships
Natural
landslides
fires
floods
avalanches
Manmade
Insecticides
herbicides
hunting
habitat destruction
The Structure of Populations
Geographic Distribution
Boundaries of the Geographic Range
The ability of a plant species to spread throughout a geographic area is the result of its adaptations to the abiotic and biotic components of the at area
Limiting Factor
A factor that limits the rate of growth for an organism
Water
light
Biotic Factors
Soil Factors
Local Geographic Distribution
Random
No obvious pattern to the position of individuals with no predictive value
Clumped
Spacing between plants is either small or large, rarely average
Uniform
All individuals are evenly spaced from their neighbors
may be caused by allelopathic zones of inhibition
Age Distribution: Demography
The relative proportions of young, middle-aged, and old individuals
Rate of Population Growth
Generation Time
The length of time from birth of an organism to the birth of its first offspring
Intrinsic Rate of Natural Increase
The number of offspring produced by an individual that live long enough to reproduce
Measured under ideal conditions that do not often occur in nature
Carrying Capacity
The number of individuals that can be sustained by an ecosystem
symbolized by
K
when
N
(individuals) equals
K
, the rate of birth and death are equal
overshoots and die-offs
R
- and
K
- Selection
R
- Selection
R
=biotic potential
Usually produced by a disturbance
Freezing temperatures
lethal hot/dry conditions
Human Disturbances
Farming
Mining
Building Cities
Damming Rivers
R
- selected species
annuals or small shrubby perennials
K
- Selection
In a
k
- habitat, almost every possible site for growth is filled
k
- selected species face intense competition from other plant species
The Structure of Ecosystems
Physiognomic Structure
The physical size and shape of the organisms and their distribution in relation to each other and the physical environment
system of life forms was defined by C. Raunkiaer 1934
Therophytes
Annual life span, survive stress as seeds
Geophytes
Buds are underground on rhizomes, bulbs, corms
Hemicryptophytes
Buds are located at surface of soil, protected by leaf and stem bases: many grasses and rosette plants
Chamaephytes
Buds are located above ground but low enough to not be exposed to strong winds: small shrubs
Phanerophytes
Buds are located high, on shoots at least 25 to 30 cm above ground: trees and large shrubs
Temporal Structure
Changes an ecosystem undergoes with time
time span can be short as a day or can encompass seasons or decades
plants change dramatically with the seasons
Species that bloom early in spring usually form fruits and mature seeds during summer; species that flower release their seeds in late summer or autumn
Late summer and autumn bring changes that depend on the ecosystem
In tropical ecosystems, winter and summer do not exist but instead dry/wet seasons govern ecosystem change
Species Composition
The number and diversity of species that coexist in an ecosystem
stressful climates with poor soils support a low number of species
mild climates and rich soils support an abundance of species
Competition is intense
Trophic Levels
Autotrophs
Bring energy into the system by photosynthesis
primary producers
energy source for the primary consumers
Secondary consumers consume primary consumers
Tertiary consumers are top predators
Decomposers break down all remains
Energy Flow
plants photosynthesize energy and carbon into the ecosystem, as they are consumed the energy and carbons move to the herbivores, then to the carnivores, finally to the decomposers
much of the food is used in respirations
Carbon dioxide is released back into the atmosphere where it can be used in photosynthesis again