An Introduction to
Ecology
The Distribution and Adaptations
of Organisms
Introduction to Ecology


Ecology is the study of organisms and their
interactions with their environment.
The environment includes 2 types of factors:

Biotic factors – the living parts of the environment


Plants, animals, bacteria, fungi, protists
Abiotic factors – the nonliving parts of the environment

Water, oxygen, light, temperature, etc.
Levels of Organization

Ecologists can look at the world in levels of increasing complexity:
 Population –
 A group of organisms of the same species that live together in
a certain area
 Example:
 Community –
 A group of organisms of different species that live together in
a certain area
 Example:
 Ecosystem –
 All the living and nonliving things in a certain area
 Example:
 Biome – a group of ecosystems that have similar climates and
communities
 Example:
 Biosphere – the entire portion of the planet that supports life
The Importance of Abiotic
Factors


Not every organism can live everywhere on Earth
Abiotic factors determine which organisms can
survive where:






Temperature – effect on body temperature
Water – too much/not enough water
Light – availability for photosynthetic organisms
Wind – amplifies effects of temperature
Rocks/Soil – which organisms can live with/on them, based
on pH and mineral composition
Periodic Disturbances – catastrophes, such as tornadoes,
fires, tsunamis, etc.
Homeostasis


Organisms must maintain homeostasis, a steadystate internal environment, despite changes in the
external environment
Organisms respond to abiotic factors in one of two
ways:
1. Regulators (endotherms) maintain a nearly
constant internal environment, despite external
conditions (Cold-blooded)
2. Conformers (ectotherms) allow their internal
environment to vary (Warm-blooded)
- live in environments which remain relatively
stable
The Principle of Allocation

This principle states:

Each organism has a limited amount of energy
that can be spent on obtaining food, escaping
from predators, coping with environmental
fluctuations (maintaining homeostasis), growth,
and reproduction
Adapting to Changing Conditions

Organisms can respond to their changing
environments using 3 different types of responses:
1. Physiological Responses
- changing the functioning of the body
- acclimation
- athletes in Torino, moving to Denver...
2. Morphological Responses
- changing the anatomy (structure) of the body
- example: dogs growing thicker fur
Adapting to Changing Conditions
3. Behavioral Responses
- changing behavior to adapt to the change
- moving to a more favorable location
- cooperative behavior (huddling, etc.)
Biomes


Aquatic
Terrestrial (Our focus will be on these!)









Tundra
Taiga
Tropical Forest
Savanna
Chaparral
Desert
Temperate Grassland
Temperate Deciduous Forest
Let’s work together to research & fill in Terrestrial Biome
Chart!
Tundra








Arctic = 20-60 cm/yr.
Alpine (mountains) = may exceed 100 cm
Average winter temp. -30 degrees C
Summer < 10 degrees C
Long winter; short summer
Herbaceous (low) plants, a few DWARF shrubs due
to PERMAFROST.
Musk oxen, caribou, reindeer, bears, wolves,
various birds
High latitudes or highest elevations (even at
equator!)
Taiga (Northern Coniferous
Forest)







30-70 cm ; some much more
Winters -50 degrees C in winter
Summer 20 degrees C
Long winter; short summer may be hot
Plants: cone-bearing trees, diverse
shrubs,herbs
Animals: Birds, moose, bears, Siberian tigers;
insects
Northern N. Am. and Eurasia to edge of
tundra
Tropical Forest







T. Rainforest: 200-400 cm/yr
T. Dry forest 150 – 200 cm/yr
25-29 degrees year round (Warm!)
Summer year round
Plants: diverse; 4 or more layers
Animals: diverse: 5-30 million species yet to
be discovered!
Equatorial regions
Savanna






Seasonal rainfall; 30-50 cm/yr with long drought
season
Temperature: 24-29 degrees C (warm!); more
variation that Tropical forests
Dry season lasts 8-9 months
Plants: Scattered trees; thorny; small leaves
(why?)Grasses; Must be fire & drought tolerant
Animals: Herbivorous mammals; insects; grazers
Equatorial & subequatorial regions
Chaparral






Seasonal ppt.; Rainy winter; Long dry summer (3050 cm)
Cool fall, winter, & spring (10-12 degrees C)
Summer can reach 30-40 degrees C
Plants: shrubs, small trees, grasses; adapted to
drought; some have seeds that germinate after fire.
Animals: mammals (browsers) amphibians, reptiles,
insects
Mid latitude coasts
Desert






< 30 cm / yr (arid/dry)
Hot deserts > 50 degrees C
Cold deserts (Antarctica) <-30 degrees C
Temps vary seasonally and daily (colder at
night)
Plants: Cacti, shrubs w/ deep roots (why?);
small leaf surface area (why?)
Animals: lizards, scorpions; birds; insects;
many nocturnal animals (why?)
Temperate Grassland





Dry winters; wet summers;; 30-100 cm/yr.;
seasonal drought
Cold winters < -10 degrees C; Hot summers
30 degrees C
Plants: Grasses
Animals: Large grazers; burrowing mammals
Plains & prairies around the world
Temperate Deciduous Forest






70-100 cm/yr
Cold Winters 0 degrees; Hot summers 35
degrees C; 4 distinct seasons
Plants: Trees, shrubs, herbaceous layer;
(broadleaved, deciduous plants)
Animals: variety of mammals, birds, insects
Midlatitudes
Our biome!