Transcript Species - Lakeland Regional High School

FOCUS ON THE BIOTA
Metabolism, Ecosystems & Biodiversity
The Earth is the only place in the solar systems
that has documented proof of life
CHARACATERISTICS OF LIFE

Life spreads exponentially

the rate of population growth depends on the number
of individuals reproducing at any time

Exponential Growth


If each pair produces 4 offspring, the number of organisms
increases exponentially
If resources become limited, exponential growth ceases
CHARACATERISTICS OF LIFE

Life needs energy
photosynthesizers use solar energy
 chemosynthesizers use chemical energy
 most other organisms use the energy stored as the
bodies of the these two

CHARACATERISTICS OF LIFE

Life pollutes

every organism has a metabolism that releases
waste products
other organisms may use these waste products
 or the waste products may accumulate in the environment

CHARACATERISTICS OF LIFE

Life is versatile

organisms react with their environment and with
each other in many ways

microbes are particularly inventive
 they occupy an incredible range of environments
 their activities are important for all life on Earth
AUTOTROPHS AND HETEROTROPHS

In Earth System Science - more useful to classify
organisms based on the way that they obtain their
energy and metabolize it (rather than by traditional
taxonomic classification system)
AUTOTROPHS AND HETEROTROPHS
AUTOTROPHS – grow using a source of energy to
reduce CO2 to organic carbon
 These organisms produce organic matter from
inorganic carbon sources using either the Sun’s
energy or that of energy-releasing chemical reactions


Plants, algae and photosynthetic microbes (cyanobacteria,
purple and green sulfur bacteria)


Most common
Chemosynthetic bacteria make up most of the remainder
of the pack (colorless sulfur bacteria)
Chemosynthesis is the basis of the mid-ocean ridge
food chain.
AUTOTROPHS AND HETEROTROPHS

HETEROTROPHS - organisms that grow by using
organic matter produced by other organisms

heterotrophs use autotrophs by breaking them down (and
using their stored energy) at a higher rate than they
would abiotically
STRUCTURE OF THE BIOSPHERE

Species – all closely related organisms that can
potentially interbreed and produce fertile offspring



Population – all members of a single species that live in
a given area
Community – characteristic assemblage of two or more
groups of interacting species


boreal forest and prairies of Saskatchewan
Ecosystem – community of plants, animals, fungi, and
microbes coupled with the environment (climate, soil and
rock type, etc.)


May include any combination of plants, animals, fungi, and
microbes
Biome – region with a characteristic plant community


Species represent the smallest subunit of the biosphere
Coral reef, tropical cloud forest, and arctic desert
Biosphere – all ecosystems on Earth
Ecosystems
The physical environment
(topography, soil type,
atmosphere, climate)
plays a strong role in
establishing an ecosystem
However, the organisms
present may also play a
strong role in altering the
physical environment in a
number of ways (creating
soil, decreasing albedo,
etc.).
PHYSIOLOGY VS. ECOLOGY FOR MAXIMUM
GROWTH
C3 – trees, plants,
cyanobacteria, algae
 C4 – grasses, corn,
pineapple


evolved in last 10-20
million years as CO2
levels dropped or
climate became drier
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ECOTONE- A DIFFUSE BOUNDARY BETWEEN
ECOSYSTEMS
- MAY CONTAIN AN ASSEMBLAGE OF SPECIES THAT IS
NOT FOUND IN EITHER ADJACENT ECOSYSTEM
MAJOR TERRESTRIAL BIOMES
Polar biomes – characterized by very
low temperatures throughout the year,
with the permanent presence of snow
and ice. This eliminates the possibility of
significant terrestrial vegetation, although
microscopic algae, cryovegetation, may
develop temporarily on the ice or snow.
This lack of terrestrial producers results
in very low diversity in polar biomes.
Tundra biomes – develop in regions where MAT is low, but where a short
summer season permits development of terrestrial vegetation
Boreal Forest or Taiga biomes form where winters are long and cold,
but the growing season is long
enough to eliminate permafrost.
Extensive, conifer-dominated forests
develop. Landscapes tend to be flat,
as a consequence of earlier glacial
activity, and bogs, ponds, and lakes
are common, often as a result of
beaver activity in damming streams.
FEEDBACKS BETWEEN THE BOREAL FOREST
AND CLIMATE IN NORTH AMERICA AND ASIA
Models predict that April temperatures might be 12°C
(21.6°F) colder and even July temperatures may decrease
by 5°C (9°F) if the boreal forest disappeared
Cold Desert biome – typically dominated by dry-adapted shrubs, such as the
sagebrush (Artemisia) and rabbit-bush (Chrysothamnus) shown here, along
with arid grasses and seasonal herbaceous dicots.
"Short-grass" Prairie biome – along the eastern front of the Rocky Mountains.
Temperate Deciduous Forest biome – dominated by trees that drop
their leaves during the winter (cold) months of the year. Temperate
deciduous forest covers much of the United States, east of the
Mississippi River.
Tropical Rainforest biome –
form where rainfall is abundant
throughout the year
Tropical Deciduous Forest
biomes – form where generally
rainy areas have a distinct dry
season.
Thorn Forest Scrub,
Savanna, and Tropical
Grassland biomes - form in
the semi-arid tropics, where
available rainfall will no
longer support true forest
vegetation, leading to the
development of a mosaic of
open biomes.
Warm Desert biome – this is the
particularly rich warm desert flora
of Sonoran Desert.
In very dry deserts like the Namib
of Africa or the Atacama of South
America, vegetation may be
virtually absent, except following
very rare rains.
NUTRIENT RESIDENCE TIMES & NET
PRIMARY PRODUCTIVITY
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SPECIES INTERACTIONS

primary producers (algae, plants) are consumed
by primary consumers (zooplankton, rodents)
that are eaten by secondary consumers (fish,
hawks), while decomposers (bacteria and fungi)
and detritus feeders consume the organic matter
of primary and secondary producers and
consumers
Food chain – charts which organisms feed on which
Food web – interconnected food chains that can be ordered as
trophic levels
Biomass – the total combined weight of organic material in each
trophic level. Biomass decreases with each increase in trophic
level. In terrestrial ecosystems, the biomass decreases by 90-99%
for each level. The exchange of biomass can be thought of as
exploitation efficiency.
Higher trophic levels– all carnivores
2nd trophic level – all herbivores
1st trophic level – all producers
SPECIES INTERACTIONS

Symbiosis – a relationship where two species
benefit from living together in intimate contact.
SPECIES INTERACTIONS

Competition – a relationship where two species
vie for the same resources
Niche – describes an
animal’s lifestyle (where,
when, and what it eats,
where it lives, where and
when it nests, etc.)
Most organisms have
different niches to reduce
competition
ECOSYSTEM DISTURBANCE AND
SUCCESSION
Disturbance of an ecosystem generates a predictable
sequence of response called succession.
In the example of a forest fire the first species to appear are
called opportunists or pioneer species. These spread fast by
reproducing rapidly and are tolerant of disturbed environments.
Return to original conditions may take hundreds of years (ex.
New England forests, Mt. St. Helens). This is the biosphere’s
way of healing after being wounded.
IS RESILIENCE A GENERAL
CHARACTERISTIC OF DIVERSE
ECOSYSTEMS?
A HEALTHY PLANET SHOULD . . .
Transport nutrients from where they are to
where they are needed
 Eliminate wastes
 Have stable environmental variables
(temperature, composition)
 Be capable of responding to disturbances while
minimizing consequences

THE BIOTA PLAY AN IMPORTANT ROLE IN
THE REGULATION OF THE EARTH SYSTEM
- modifies greenhouse gas content
- created O2-rich atmosphere
EARTH’S HEALTH CAN BE
MEASURED BY THE NUMBER OF
SPECIES IT SUPPORTS
Biodiversity
Biodiversity is the number of species in a given area. However,
there are other ways to look at biodiversity too.
Biodiversity is the same in both plots.
Community II is much more
heterogeneous and therefore
diverse.
Simpson’s diversity index
measures the likelihood that two
individuals drawn from the same
community will be of different
species.
SDI = 1- [(proportion of species A)2 + (proportion of species B)2 + …]
1 = Very High Diversity
0 = Very Low Diversity
SDI for community I (1- (0.992 + 0.012) = 0.02
SDI for community II (1- (0.52 + 0.52) = 0.50
Diversity and Stability
Time Stability Hypothesis- environmental stability like that seen
in the tropics leads to high diversity
Intermediate Disturbance Hypothesis- the high diversity in the
tropics is the result of disturbances that occur with intermediate
frequency and intensity
Rainforests tend to show greatest diversity where
some disturbance has occurred
Coral reefs show maximum diversity where they are
most likely to get trashed in storms.
It may be that a world with greater biodiversity will recover more
quickly from a disturbance and thus a more diverse world is a
more stable world.
Decreases in some species counterbalanced by increases in
others
DIVERSITY INDEX FOR THE EARTH SYSTEM

SHOULD
Capture the degree of interactions between biological
and physical components
 Incorporate the attribute of redundancy
 Incorporate potential diversity

A more biologically diverse Earth would be more
stable and resilient
 Biodiversity does enhance environmental
stability on a global scale

DANGERS OF LOSS OF BIODIVERSITY
An Gorta Mór- implications for low diversity
Monocultures  famine, disease,
social breakdown