bio

1. La geosfera
The structure of
ecosystems

2. La geosfera
© Oxford University Press España, S. A. 2
Gené%ca mendeliana
1. ENVIRONMENTAL FACTORS
The characteris%cs of the environment that affect living things are called
environmental factors (or ecological factors). They can be:
• AbioLc factors. They are the physical and chemical condi%ons that affect
living things: water, temperature, light, soil, pH, humidity and nutrients found
in soil or water.
• BioLc factors are the organisms that share the same natural environment.
Living things have complex rela%onships that can be of two different types:
The structure of ecosystems
Ø Intraspecific relaLonships: those
between individuals of the same
species.
Ø Interspecific relaLonships: those
between individuals of different
species.

3. La geosfera
© Oxford University Press España, S. A. 3
LimiLng factors
LimiLng factors determine the extreme values aDer which an organism cannot
develop properly. Therefore, they can limit the growth of a popula%on.
Origen y evolución de la vida
The structure of ecosystems

4. La geosfera
© Oxford University Press España, S. A. 4
Gené%ca mendeliana
2. ADAPTATIONS OF LIVING THINGS TO THE ENVIRONMENT
AdaptaLon is the evolu%on of organisms so that they are able to survive in a
specific environment. Adapta%ons can be morphological, psychological or
behavioural.
The structure of ecosystems
AdaptaLons to water scarcity

5. La geosfera
© Oxford University Press España, S. A. 5
Origen y evolución de la vida
The structure of ecosystems
AdaptaLons to temperature changes

6. La geosfera
© Oxford University Press España, S. A. 6
Origen y evolución de la vida
The structure of ecosystems
AdaptaLons to sunlight
Sunlight condi%ons are different in aquaLc environments. When sunlight goes
through the water, some wavelengths, which plants use for photosynthesis, are
absorbed. The area that receives sunlight is referred to as the phoLc zone. Algae
have special pigments that allow them to use the wavelengths at par%cular
depths:

7. La geosfera
© Oxford University Press España, S. A. 7
Origen y evolución de la vida
The structure of ecosystems
AdaptaLons to a lack of oxygen
High alLtudes
Animals that live in these areas have developed the following adapta%ons in:
• An increase in red blood cells, which are smaller too.
• An increase in lung capacity.
AquaLc environments
• They reduce their heart rate when they are
underwater.
• Cetaceans have a higher percentage of blood
than other mammals.
• Their blood has a higher number of red blood
cells.
• They accumulate oxygen in their muscles and
blood.
• Blood flow to organs is reduced (except to the
heart and brain).

8. La geosfera
© Oxford University Press España, S. A. 8
Origen y evolución de la vida
The structure of ecosystems
AdaptaLons to varying salt concentraLons
• If the environment has a high concentra%on of salt, too much water leaves
the organism, causing it to die.
• If the concentra%on of salt is too low, too much water enters the organism
and it cannot survive.
Freshwater fish
Saltwater fish

9. La geosfera
© Oxford University Press España, S. A. 9
Origen y evolución de la vida
The structure of ecosystems
AdaptaLons to a lack of food
Food can be scarce during certain %mes of the year. To survive, organisms have
developed a range of adapta%ons:
Mammals:
• Some hibernate.
• Their heart rate and respiratory rate slow down and their body temperature
decreases.
• During the months before winter, some mammals accumulate a layer of fat
under their skin.
• Some mammals adapt their behaviour.
RepLles:
• They spend the cold months in
a lethargic state, when food is
less abundant.

10. La geosfera
© Oxford University Press España, S. A. 10
Gené%ca mendeliana
3. POPULATIONS
A popula%on is a group of organisms of the same species that live in the same
territory and can reproduce together. The rela%onships established between the
individuals of a popula%on are referred to as intraspecific relaLonships. They
can be:
• CoopetraLve intraespecific rela%onships: colonies, families, caste system or
social.
• CompeLLve intraespecific rela%onships.
• Intraespecific rela%onships by passive transport.
The structure of ecosystems

11. La geosfera
© Oxford University Press España, S. A. 11
Gené%ca mendeliana
4. COMMUNITIES
A community, or biocoenosis, refers to the group of popula%ons that live in the
same area and have rela%onships between each other.
The different species in a community can have rela%onships with each other. These
types of rela%onships are referred to as interspecific relaLonships and can be:
• Favourable: mutualism, symbiosis, commensalism y protocoopera%on.
• Harmful: parasi%sm, preda%on y compe%%on.
The structure of ecosystems

12. La geosfera
© Oxford University Press España, S. A. 12
Gené%ca mendeliana
5. ECOSYSTEMS
An ecosystem is the combined group of living things, the physical factors of the
environment where they live, and the bio%c and abio%c rela%onships between
them. The components of an ecosystem are:
• Biotope
• Biocoenosis
• Habitat
• Ecological niche
The structure of ecosystems