Transcript Chapter 9 Habitats, environment and survival

Chapter 9
Habitats, environment and
survival
Page 256 - 296
Ecology
O
2
CO
2
Ecology is the study
of the relationships
between organisms
and their physical
(abiotic) and living
(biotic) environment:
Relationships involve
interactions with the
physical world as well as
interrelationships with other
species and individuals of
the same species.
Nutrients
Habitat
An organism’s habitat is the physical place or
environment in which it lives.
Organisms show a preference for a particular
habitat type, but some are more specific in their
requirements than others.
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.
Habitat Type:
Habitats can be described as being either:
• Terrestrial (for example, deserts, grasslands, rainforests
etc), or
• Aquatic:
– Freshwater: lakes, rivers, ponds
– Marine: coral reefs, coastal sea floor, seas, oceans etc
– Estuarine: river mouths
Example: Within a woodland
habitat, woodlice may be found in
the microhabitat provided
Microhabitat:
beneath the bark of the rotting
wood.
Defn: the more localised part of a general habitat where an organism lives
(examine Figure 9.7. Describe: a) The habitat; b) Microhabitats
Abiotic Factors that influence a habitat
The physical conditions influence the habitat in which an
organism lives. These include:
substrate
humidity
sunlight
temperature
salinity
pH (acidity)
exposure
altitude
depth
Each abiotic (or physical) factor may be well suited to the
organism or it may present it with problems to overcome.
Biotic Factors that influence a habitat
The living factors that influence the habitat in which an
organism lives include:
predators
prey
competition
disease
Each biotic (or livingl) factor may be well suited to the
organism or it may present it with problems to overcome.
Resources in a Habitat
The habitat provides
organisms with the following
resources:
Food and water sources
Mating sites
Nesting sites
Predator avoidance
Shelter from climatic
extremes
However, the organism may
or may not have the
adaptations to exploit all the
available resources fully
.
Range of Habitats
• Range: The geographical area that encloses all the
habitats where a species lives denotes the range or
distribution map of that species.
– Over time the range of a species may increase or decrease.
– Many native species have a shrinking range.
– In contrast, many introduced species have increased their range.
Examine Figure 9.9 – 9.11
Discussion: What factors affect the range of an organisms Habitat?
Resources in a Habitat
The habitat provides
organisms with the following
resources:
Food and water sources
Mating sites
Nesting sites
Predator avoidance
Shelter from climatic
extremes
However, the organism may
or may not have the
adaptations to exploit all the
available resources fully.
Dingo Habitats
Dingoes are a highly
adaptable species found
throughout Australia in
ecosystems as diverse as
the tropical rainforests of
the north and the arid
deserts in the central
Australia.
Within each of these
ecosystems, they may
occupy a range habitats,
each one offering slightly
different resources.
Biozone: Dingo Habitats page 245
Hills
Floodplain
Hills and Floodplain
Floodplains and Hills
Floodplains
Dingoes prefer riverina habitat.This is inferred by the fact that
they spend a disproportionate amount of time in riverina
compared to the other habitats available. Stoney areas avoided
Dingos are caught and fitted with radiotransmitters. At set
intervals the from the individual animals can be recorded and
mapped giving a picture of movements over time
4194
4 years
Provides more accurate information about size and boundaries of range
Possibly plays some part since the areas with very low kangaroo abundance
also have low dingo numbers. However other limiting (i.e available of suitable
riverina habitat) are importnatHigh kangaroo numbers does not necessarily
equate with high dingo numbers. Trade off between food and other factors
Home range is larger where water (and vegation) are scarce.
Areas with poor water supply offer little little in the way of vegatation
diversity
Quick Check Questions
Technology as a tool
• Using technology is an important tool in the study of habitats,
particularly those over large areas.
• Remote Sensing (such as Landsat) carries sensors that
detect the distinctive ‘signatures’ of different kinds of
vegetation.
• Tracking or telemetry techniques are restricted to animals of
restricted size to allow a tracking device to be fitted to them.
• Tags attached to animals can record data on animals’
interactions with their environment.
Quick Check Questions
Mudfish Habitat Preference
The New Zealand black
mudfish is a wetland species of
uncertain conservation status.
Its habitat preference has been
described in relation to mean
water depth, turbidity, and
degree of habitat disturbance.
Black mudfish Neochanna diversus
Law of Tolerance see page 243 Biozone
The law of tolerance states that “For each abiotic factor, an
organism has a range of tolerances within which it can survive.”
Tolerance range
Number of organisms
Optimum range
Unavailabl
e niche
Examples of
abiotic factors
that influence
size of the
realized niche:
Margina
l niche
Preferre
d niche
Marginal
niche
Unavailable
niche
Community and Niche
Defn: Community
• Members of the different species that share one habitat form the
living community of that habitat.
Case study pg 268
Defn: Niche
• The niche of a species identifies its way of life or role in a
community.
• A niche can be identified in terms of the degree of use of resources.
• Activity Manual pg 247
• Quick Check Questions: 5 – 11
Ecological Niche text page 269
The ecological niche
describes the functional
position of an organism in
its environment.
Habitat
Adaptations
A niche comprises:
the habitat in which the
organism lives.
the organism’s activity
pattern: the periods of
time during which it is
active.
the resources it obtains
from the habitat.
Activity
patterns
Presence of
other organisms
Physical
conditions
The Fundamental Niche
The fundamental niche of an
organism is described by the full
range of environmental
conditions (biological and
physical) under which the
organism can exist.
The realized niche of the
organism is the niche that is
actually occupied. It is narrower
than the fundamental niche.
This contraction of the
realized niche is a result of
pressure from, and
interactions with, other
organisms.
Gause’s Principle
Gause’s competitive exclusion principle states:
“two or more resource-limited species, having identical patterns of
resource use, cannot coexist in a stable environment:
one species will be better adapted and will out-compete or otherwise
eliminate the other(s)”.
Amount eaten
If two species compete for some of the same resources (e.g. food
items of a particular size), their resource use curves will overlap.
In the zone of overlap, interspecific competition is the most
intense.
Zone of overlap
Species
A
Species
B
Resource use as measured by food item size
Competition
Competition describes the
active demand between two or
more organisms for a resource.
Competition may be:
Intraspecific: between
individuals of the same
species.
Intraspecific competition: hyaenas
Interspecific: between
individuals of different
species.
Each competitor is inhibited in
some way by the interaction.
Interspecific competition on a reef
Biozone: Ecological Niche page 244
Quick Check 8 – 11: page 270
• Mud at lake edge; probing with beaks; worms and small crustaceans
• Deepest water; diving; small organisms at the botton etc
In general, two or more different species cannot occupy the
same niche in the same community for an extended period
yes
No
yes
• Quick Check questions 12 – 17
• Activity Manual page 231- 234
false
true
true
P
hygrometer
Conductivity meter
anemometer
•
•
•
Moisture
Temperature range
etc
false
true
false
true
Surviving in the Australian Environment
• Much of the Australian environment is distinguished by
high summer temperatures, low and erratic rainfalls and
mineral poor soils.
• Adaptations for survival in the conditions prevailing in a
particular environment may be structural, physiological
or behavioural features.
• Different vegetation type can be defined by light
penetration, climate, dominant family.
• The distribution of various vegetation types is influenced
by environmental factors mainly related to climate, but
also soil type.
Plant Adaptations to Australian Environments
• Adaptations plants have for arid environments include:- maximise water uptake – root systems
- minimise water loss – leaf structure (SA: V)
- produce drought-resistant seeds
– Response to fire
Adaptations by Animals
•
•
•
•
Reproductive strategies
Sweeting/ panting
Behaviour
Torpor
• Quick Check Questions 18, pg 282
• Activity Manual pg 239-40 and 241-2