AP Biology

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

Levels of increasing complexity: Population –

A group of organisms of the same species that live together in a certain area

Community – A group of organisms of different species that

live together in a certain area Ecosystem –

All the living and nonliving things in a certain area

Biome – a group of ecosystems that have similar climates and communities

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 steady-state

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 Conditions3. 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

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 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 (30-50 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!