Coping with Environmental
Autotrophs: Assimilate radiant
energy from sunlight
(photosynthesis), or from inorganic
The energy is converted into
chemical energy stored in the
bonds of organic molecules.
Climatic Variation over Time
seasonality results from the annual orbit of Earth around the sun
Earth is tilted at an angle of 23.5 relative to the suns direct rays.
The angle and intensity of the suns rays striking any point on Earth vary as Earth orbits
A population can be characterized by its age structurethe proportion of the population in each
Age structure influences how fast a population will grow.
If there are many people of reproductive age (15 to 30), it will grow rapidly
Adaptations result from natural selection
Natural selection is the only evolutionary mechanism that consistently causes adaptive evolution
Adaptations are features of organisms that improve their ability to survive and reproduce.
DELAYED DENSITY DEPENDENCE
Definition : Delays in the effect that density has on population size.
The effect of population density os often delayed in time
Commonly, the number of individuals born in a given time period is influenced by population den
JOINT EFFECTS OF ECOLOGY AND EVOLU
Evolution can alter ecological interactions.
If a predator evolves a new way to capture prey, prey species may go extinct, decline, migrate t
o other areas, or
evolve new ways to cope with the more efficient predato
The Web of Life - Ecology
Definition of Ecology
The scientific interactions between organisms and their environment
E.g. sidewalk and corn field
Organisms are important part of one anothers environment
The scientific study of interactions that determine t
RESPOND TO ENVIROMENTAL VARIATION
Species distributions reflect environmental influences on energy acquisition and
The physical environment influences an organisms ecological success in two ways:
1. Availability of energy and reso
One of the ecological maxims is: No population can increase in size forever.
The limits imposed by a finite planet restrict a feature of all species
A capacity for rapid population growth.
Ecologists try to understand the factors
EFFECTS OF DENSITY
Population size can be determined by densitydependent and densityindependent factors.
Under ideal conditions, > 1 for all populations.
But conditions rarely remain ideal and fluctuates over time.
Densityindependent factors can determine
9 Major Terrestrial Biomes
Climate diagrams show the characteristic seasonal patterns of temperature and precipitation at
a representative location.
1. Tropical Rainforests
Warm, seasonally invariant temperature
Most precipitation spread evenly throughout
Evolution and Ecology
Trophy Hunting and Inadvertent
Evolution: A Case Study
Bighorn sheep populations have been
reduced by 90% by hunting, habitat loss,
and introduction of cattle. Hunting is now
restricted; permits for a large trophy ram
cost over $100,
The biosphere is the zone of life on Earth.
Biomes are large-scale biological
communities shaped by the physical
environment, particularly climate.
Biomes are categorized by dominant plant
forms, not taxonomic relationships.
Plants occupy si
Coping with Environmental Variation:
Temperature and Water
The physical environment influences an
organisms ecological success in two ways:
Availability of energy and resources
impacts growth and reproduction.
Extreme conditions can exceed tolerance
1. the scientific study of interactions between
organisms and their environment
2. the scientific study of interactions that determine
the distribution (geographic location) and abundance of
- other meanings in public usage
LIFE HISTORY CONTINUA
Classification schemes for reproductive patterns place the patterns on continua with extremes at
Some organisms reproduce only once while others reproduce multiple times.
One way of classifying the reproductive diversity of
GENERAL FEATURES OF COMPETITION
Competition, whether direct or indirect, can limit the distributions and abundances of competing
Exploitation CompetitionSpecies compete indirectly: Individuals reduce the availability of a res
they use it
How ecosystem work
Each unit of energy captured by producers is eventually lost from the ecosystem as heat. As a r
esult, energy moves
through ecosystem in a single direction only it cannot be recycled!
But nutrients (N or P) are continuously recycled fro
Population Distribution and Abundance
Population: Group of interacting individuals of the same species living in a particular area.
Interactions within populations include sexual reproduction and competition.
Populations are dynamicdistribution
Photosynthesis vs. cooling of the leaf
Closing stomates increases chance of light damage
If the Calvin cycle isnt operating, energy accumulates in the lightharvesting arrays and can dam
Plants have various mechanisms to dissipate this energ
MECHANISMS OF EVOLUTION
Natural selection, genetic drift, and gene flow can cause allele frequencies in a population to ch
ange over time.
Mutation generates the raw material for evolution
Phenotype: Observable characteristics that are determined by the g