Principles of Ecologybio 271

dr.Abdulhadi Aloufi

8th lecturewww.draloufi.com

The law of tolerance states that “For each abiotic factor, an organism has a range of tolerances within which it can survive.”

Law of Tolerance

Tolerance range

Optimum range

Unavailable niche

Marginal niche

Num

ber of organism

s

Preferred niche

Marginal niche

Unavailable niche

An organism’s habitat is the physical place or

environment in which it lives.

Habitat

Lichens are found on rocks, trees, and bare ground.

Most frogs, like this leopard frog, live in or near fresh water, but a few can survive in arid habitats.

The habitat provides organisms

with the following resources:

—Food and water sources

—Mating sites

—Nesting sites

—Predator avoidance

—Shelter from climatic extremes

Resources in a Habitat

An adaptation is an inherited

feature of an organism that enables

it to survive and reproduce in its

habitat.

Adaptations

Osprey: a diurnal bird of prey

Spotted owl: a nocturnal bird of prey

1. Structural adaptations: physical features of an organism, e.g. presence of

wings for flight.

2. Behavioral adaptations:the way an organism acts, e.g. mantid behavior when seeking, capturing, and manipulating prey.

3. Functional (physiological) adaptations:those involving physiological processes, e.g. the female mantid produces a frothy liquid to surround and protect the groups of eggs she lays.

Types of Adaptations

Structural Adaptations in Rabbits

Structural adaptations

Widely spaced eyes gives a wide field of vision for surveillance of the habitat and

detection of danger.

Long, mobile ears enable acute detection of sounds from many angles for predator

detection.

Long, strong hind legs andlarge feet enable rapid movement

and are well suited to digging.

Cryptic coloration provideseffective camouflage in

grassland habitat.

Functional Adaptations in Rabbits

Functional adaptations

High reproductive rate enables rapid population increases when food is available.

Keen sense of smell allows detection of potential threats from predators and from rabbits from

other warrens.

Microbial digestion of vegetation in the hindgut enables more efficient digestion of cellulose.

High metabolic rate and fast response times enables rapid response to dangers.

Hawks are major predators of rabbits

Behavioral Adaptations in Rabbits

Behavioral adaptationsFreeze behavior when startled reduces the

possibility of detection by wandering predators.

Thumps the ground with hind legs to warn others in the warren of impending danger.

Lives in groups with a well organized social structure that facilitates cooperative defense.

Burrowing activity provides extensive underground habitat as refuge from

predators.

Freezing is a typical behavior when threatened

The home range is the physical area of an organism’s normal activity. It provides all of the resources required for the organism’s survival.

Home Range=Territory

Marking a Home Range

The boundaries of a home range may be marked by:

1. calls and displays

2. scent marking, urination, defecation

3. scratching, biting, or rubbing on vegetation.

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