Understanding Biotic Potential and Population Dynamics
Biotic Potential: The main contributing factor to the increase in population is the number of offspring that each species can produce under ideal conditions. Because the cubs should take effect and be able to play, Another Factor is that animals can migrate or disperse seeds, which increases the rate of population growth.
Strategies of Reproduction
- A high birth rate and high mortality of pups, as seen in fish.
- A small birth rate and low mortality of pups, typical of mammals that care for and protect their young.
Exponential Growth and Population Explosion
The growth curve represented as a J is a graph showing the number of individuals in a population as a function of time in an environment with unlimited resources. This is called a population explosion when the population increases exponentially over time. Environmental resistance refers to the set of biotic and abiotic factors that limit population growth.
S-shaped Population Growth
If we represent a graph with population growth as a function of time in an environment with limited resources, we derive a growth curve in the form of S. Growth is held back until it reaches a maximum size. The carrying capacity (K) is the maximum population that a particular habitat can support without degrading itself.
Balance Between Predator and Prey
A population may grow in the absence of predators. If the predator population decreases while the prey population grows, a balance is disrupted.
Competition and Population Balance
If two species use the same resources, only the species that is better adapted will survive, eliminating the other.
When the Balance is Broken: Pests
An organism is considered a pest if it interferes directly or indirectly with human activity. It is difficult to remove them, but it is possible.
Pesticides
A pesticide is a chemical that can kill undesirable organisms. Pesticides can be classified as insecticides, herbicides, fungicides, rodenticides, etc. Ideally, a pesticide would eliminate pests without harming any other living beings, but such a product does not exist.
Integrated Pest Control
Biological controls are used, such as:
- Introducing natural predators and parasitic pathogens.
- Sterilizing insect males and releasing them to compete against fertile ones.
- Using traps and poisons to attract pests.
Integrated control aims to guarantee human health, wildlife, and the environment without overusing chemical pesticides.
Periodic Changes in the Environment
The movement of the Sun, Earth, and Moon are sources of environmental change.
Rhythms
- Daily Rhythms: Organisms follow a schedule by alternating rest and activity throughout the day. In the marine environment, organisms migrate between day and night.
- Seasonal Rhythms: Various behaviors are associated with seasonal changes, such as plants shedding leaves, flowering, or fruit ripening, and animals undergoing reproduction, hibernation, or molting.
- Tidal Rhythms: These rhythms periodically affect organisms living on the coast. For example, sea anemones have activity rhythms associated with the tides.
Plants and Fire
Pirophytic Plants: These plants regenerate quickly after a fire, such as oaks, cork oaks, and Kermes.
Ecological Succession
Ecological succession refers to the logical progression of species after a fire, where new species emerge. A climax ecosystem is reached when an ecosystem undergoes changes and no longer has a fixed species. However, a climax ecosystem is never truly reached, as species substitutions continue to occur, influenced by the same factors in the same sequence.
Primary and Secondary Succession
Primary Succession begins in an area that has never been colonized, such as a newly formed sand dune. Secondary Succession occurs in an area where a community has been partially or completely eliminated, such as a lagoon filled with sediment.
The Ecosystem: Characteristics
An ecosystem is composed of a set of elements or components, both living and non-living. Interactions among these elements cause changes, and matter and energy flow between its components and the external environment. Solar energy enters the ecosystem and returns in the form of heat.
Effects of Human Activity
- Plants protect the soil and create coral-built islands.
- Oxygen was formed by bacteria approximately 2 billion years ago, 1.5 billion years before the emergence of life on Earth.
Soil Contamination
Overexploitation and agricultural practices, driven by population explosion, lead to soil contamination. Agricultural chemicals penetrate the soil, reaching groundwater and rivers, causing deforestation. The accumulation of urban and industrial waste also pollutes rivers and aquifers.
Water Pollution
Water pollution leads to soil contamination and affects rivers, lakes, seas, and oceans.
Air Pollution
- Acid rain causes serious damage to flora and fauna.
- The increase in greenhouse gas emissions leads to global warming.
- The destruction of the ozone layer allows harmful rays from the sun to reach the Earth.
Gaia Theory
The Gaia theory, proposed by James Lovelock, suggests that the evolution of Earth and life are interrelated. Contrary to the prevailing view in the scientific community, the conditions on the planet are influenced by life. This theory posits that the evolution of planet Earth is associated with life, and both events are part of an evolutionary process capable of self-regulation.
The physical and chemical conditions of our planet led to the emergence of life, and the activity of living organisms modifies the primitive conditions of the planet. Life regulates the biosphere, maintaining it at a certain level, while any species that harms the planet is eliminated. The Earth’s atmosphere has a physical and chemical imbalance due to the presence of life.