Ecology as a Scientific Way of Understanding the World

• Definition of Terms

  • Ecology

    • The study of the interactions among and between organisms in their abiotic (non-living/physical) environment.

    • Methods for Ecological Research

      • In situ (onsite/field) observations

      • Controlled Experiments

      • Virtual Modelling

  • Ecosystem

    • The interaction and interrelationship between the living community (plants, animals, organisms) in relation to each other and the non-living community (soil, air, water).

    • The structural and functional unit of the biosphere.

    • A geographic area where biotic (living) and abiotic (non-living) factors interact to form a unique community of organisms.

    • While we consist of multiple ecosystems, Earth itself is an ecosystem.

• Natural Systems → Balanced Systems

  • The interactions between different organisms making up an ecosystem contribute to a certain ecological stability.

  • Stability =/= Static

    • Ecosystems constantly evolve as components of the ecosystem constantly shift and adapt to attain balance.

    • Climate-related or natural phenomena can transform the environment, forcing the organisms living in the environment to adapt to the new constraints.

  • Ecosystems =/= Ideal Stability

    • Ecosystems naturally experience a degree of imbalance, both temporary and permanent ones. These imbalances may cause ecosystems to evolve slowly, quickly, or even disappear entirely.

    • Changes in the ecosystem may result in a variety of scenarios: the collapse of the dominant species (Humans), the development of alternative biological communities, to ecosystem collapse.

  • Examples:

    • Natural predation

      • The triton snail and the humphead wrasse preying on the crown-of-thorns starfish, an aquatic organism severely affecting the production of coral reefs.

      • Herbivores consuming grass while feeding the soil with nutrients from their fecal matter.

    • Environmental Conditions

      • Specific coral species are capable of living in hostile, aquatic environments (high acidity, high nutrition for algae growth, hot temperature)

    • Human activity

      • The greenhouse effect (heat from the sun being trapped in our atmosphere) being disrupted by industrialization.

      • Loss of biodiversity, environmental degradation, overpopulation, and resource conflicts.

Ecosystem and Energy Flow

• Ecosystems maintain balance by cycling nutrients and energy from various external sources throughout the ecosystem.

• Solar Energy

  • The primary source of energy in the ecosystem

  • Photosynthesis

    • 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂

    • Photosynthetically Active Radiation (PAR)

      • The Visible Light Spectrum (400-700 nm)

      • Out of the 50% PAR captured on Earth, only 1-10% is captured by plants

    • Products of Photosynthesis

      • Light-Dependent (ATP, NADPH)

      • Light-Independent (Carbohydrates)

• Trophic Levels

  • Producers (Autotrophs)

    • Capable of conversion and transformation of energy and particles

      • Inorganic Particles → Organic Particles

      • Solar Energy → Chemical Energy

    • Primarily plants, as they are capable of photosynthesis

  • Primary Consumers

    • Herbivores

    • Chemical Energy (from plants) → Kinetic Energy + Thermal (Heat) Energy

  • Secondary Consumers

    • Primarily carnivores/omnivores

    • Feed on either primary consumers and producers for energy

  • Tertiary Consumers

  • Decomposers

• Laws and Rules on Energy Flow

  • Law on the Conservation of Energy

    • Energy can neither be created nor destroyed; it can only be converted

    • Solar Energy → Chemical Energy || Chemical Energy → Kinetic Energy + Thermal (Heat) Energy

  • The 10% Rule on Energy Transfer

    • Energy consumed or transferred from one trophic level to another will only be 10% of the original trophic level’s energy.

    • Organisms require energy to perform bodily functions and dissipate heat, reducing the amount of energy gained through consumption.

  • Directionality of Energy

    • Energy flow is both unidirectional and linear, from producers → consumers

    • This can be visualized via a food chain/web

Levels of Biological Organization

• Non-Biological Levels

  • Subatomic Particles

  • Atoms

    • Smallest and most fundamental unit of matter

    • Consists of a nucleus surrounded by electrons

  • Molecules

    • The smallest particle of a specific compound that retains the chemical properties of that compound.

    • Two or more atoms held together by one or more chemical bonds.

  • Macromolecules

    • A very large molecule, especially used in reference to large biological polymers (e.g. nucleic acids and proteins) created by Polymerization

      • The chemical process, normally with the aid of a catalyst, to form a polymer by bonding together multiple identical units (monomers)

    • Example: Deoxyribonucleic Acid (DNA)

• Biological Levels

  • Organelles

    • The simplest level of biological organization.

    • Small structures existing within cells and have unique functions supporting cell life.

  • Cells

    • Fundamental Unit of Life

    • Types of Cells

      • Prokaryotic (without membrane-bound organelles or nucleus)

      • Eukaryotic (with membrane-bound organelles and nucleus)

  • Tissues (Groups of similar cells carrying out similar or related functions)

  • Organs

    • Collection of tissues grouped together performing a common function

    • Present in both animals and plants

  • Organ System

    • Organizational term of functionally related organs

    • They support an organism’s ability to function

  • Organisms (individual living entities)

• Ecosystem Levels

  • Population (all the individuals of a species living within a specific area)

  • Community (the sum of populations inhabiting a particular area)

  • Ecosystem (all biotic and abiotic aspects of a specific environment)

  • Biosphere (the collection of all ecosystems, representing the zones of life on Earth)

Community Interactions

• Predation (One Wins, Other Loses)

  • Any interaction between two species in which one benefits by obtaining resources to the detriment of the other

  • Usually results in the death or injury of the organism, with few exceptions such as Herbivores and Seed Dispersal

  • Parasitic Interactions are a form of predation, albeit one whose effects aren’t immediate

  • Examples:

    • Tapeworms and Animal/Human Intestines

    • Herbivores and Plants

• Competition (Both Lose)

  • Multiple organisms vie for the same, limiting resources

  • It can be an interspecific (between different species) or intraspecific (between same species)

  • It is likely one species will become extinct or evolution will reduce the competition

  • Examples:

    • Humans and Humans

    • Cheetah and Lions

• Mutualism (Everyone Wins)

  • An interaction benefitting both species

  • In rare instances, mutualistic partners cheat (Bees gaining food without pollinating in return)

  • Examples:

    • Alga (Nutrient Provision) and Fungus (Protection)

    • Bees and Flowers

    • Zooxanthellae and Clams, Jellyfish, Corals

• Commensalism (Positive/Zero Interaction)

  • One species benefits, the other remains unaffected

  • May be confused with mutualism depending on the specific interactions

  • Examples:

    • Cattle egrets and brown-headed cowbirds

    • Birds and trees

• Amensalism (Negative/Zero Interaction)

  • The presence of one species has a negative effect on the other, but the first species is unaffected

  • Examples:

    • Harmful Algal Bloom

    • Elephants and fragile plants

• Alien Invasive Species (AIS)

  • Non-native organisms of an ecosystem

  • Adversely affects economic, environmental, and health activities

  • Impacts local biodiversity:

    • Decline or elimination of native species

    • Disruption of local ecosystems and their functions

Ecological Succession

• Definition

  • The transition in species composition of a community

  • The change in species composition of a habitat over time

• Types of Succession

  • Primary

    • Occurs in environments without any presence of soil

    • Pioneer species (Lichens) and weathering aid in the formation of soil

    • Organisms that die and decompose add more and more organic nutrients into the soil

    • Climax community (the final stage of succession remaining relatively unchanged until destroyed by an event)

    • Examples:

      • Taal Volcano

      • Hawaii

  • Secondary

    • Initiated by an event where the already established ecosystem is reduced or drastically changed

    • Characterized by the presence of pre-existing soil

Biomes

• An specific geographic area of the planet that can be classified according to the notable species (plants and animals) living in it

• This is dictated by abiotic factors (temperature, soil composition, moisture, light, etc.)

• Latitude and Biomes

  • Provides the location of a place north or south of the equator and is expressed by angular measurements ranging from 0° at the equator to 90° at the poles

  • Delineator of Biomes

    • Different latitudes on Earth = Different amounts of sunlight

    • Higher latitudes = broad distribution of sunlight, decreasing heat

    • Lower latitudes = narrower distribution of sunlight, increasing heat

  • Seasonal Adjustments of Latitudes

    • April → September (More sunlight in the Northern Hemisphere)

    • October → March (More sunlight in the Southern Hemisphere)

• Types of Climate Zones

  • Polar

    • The regions of the earth that surround the north and south poles, from the north pole to 60 degrees north and from the south pole to 60 degrees south

    • Coldest climate zone

  • Temperate

    • A region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle)

    • It is also between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle)

  • Tropical

    • The region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south

    • Hottest climate zone

• Types of Biomes

  • Terrestrial Biomes

    • Distinguishing Factors

      • Characteristic Temperatures

        • Geographic Distribution

        • Types of Vegetation

      • Amount of Precipitation

        • Abiotic Factors

    • Tundra

      • Characterized by low, shrubby or mat-like vegetation found at extremely high latitudes or elevations, near the limit of plant growth

      • It is characterized by soil with permafrost, reducing potential biodiversity and plant growth seasons

      • Most of the year, these treeless plains are bitterly cold with ice & snow

    • Taiga

      • Coniferous or boreal forest, located in a band across northern North America, Europe and Asia.

      • Few species of trees are present, these are primarily conifers that grow

      • Adaptations of Conifers to the Environment

        • Long, thin needles

        • Thick, waxy cuticles

        • Sub-surface stomata

    • Desert/Dunes

      • Characterized by low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity

      • Allelopathy, the adaptation by desert plants in which toxic substances secreted by roots or shed leaves inhibit the establishment of competing plants nearby), is an important feature of deserts.

    • Savannah

      • Areas composed of widely scattered trees characterize savannahs.

      • It is found in areas of low or seasonal rainfall with prolonged dry periods [85-150 cm/year]

    • Grassland (An area dominated by grasses, such as a prairie or meadow good for grazing animals)

    • Rainforests

      • Found near the equator

      • Has warm temperature, high humidity and heavy rainfall, annual precipitation is from 200-450 cm

    • Ice Caps

      • A large body of land ice

      • Forms when large snowfalls and low temperatures encourage the transformation of snow into ice that persist for many years

  • Aquatic Biomes

    • Characteristics

      • The aquatic biome is the largest of all the biomes, covering about 75% of the Earth’s surface

      • Typically divided into freshwater (ponds, lakes, rivers, and streams) and marine/saltwater (the ocean and salty seas)

    • Ponds and Lakes

      • Stationary bodies of freshwater, with ponds being smaller than lakes

      • Zones in Ponds/Lakes

        • Littoral Zone

          • Along the shoreline

          • Shallow water persists, allowing light to penetrate the bottom

          • It is the most production zone of the lake as rooted plants and algae also exist.

        • Limnetic Zone

          • Away from shore

          • An open water area extending down as far as light could penetrate

        • Profundal Zone

          • The deepest zone

          • Lack of food producers due to lack of light (food is derived from other zones)

      • Layers in Ponds/Lakes (Formed through the sun’s heat [Thermal Stratification])

        • Epilimnion

          • A warm surface layer

          • Interacts with the wind and sunlight, so it becomes the warmest and contains the most dissolved oxygen

        • Metalimnion

          • The transition zone of water

          • The shallowest of the cool waters in the hypolimnion gradually warm up until they mix into the epilimnion

          • Thermocline [The point of greatest temperature difference (and therefore density difference)]

        • Hypolimnion

          • Deepest, coldest, dense layer of water

          • Contains the lowest amount of dissolved oxygen and can often become anoxic (zero dissolved oxygen) while the lake is thermally stratified

    • Rivers (Moving bodies of freshwater which travel to another water channel or to the ocean)

    • Estuary (Areas of water and shoreline where rivers meet the ocean or another large body of water)

    • Oceans (Covers 71% of the Earth’s surface and contains 99% percent of the habitable space on the plane)

Biodiversity and its Threats

• The totality of species on Earth and the ecosystems where they thrive

• Levels of Biodiversity

  • Genetic Diversity (each individual species possesses genes which are the source of its own unique features; diversity within species)

  • Species Diversity (number of species and abundance of each species that live in a location)

  • Ecosystem Diversity (variety of different ecosystems within an area)

• Importance of Biodiversity (Sustaining Human Livelihoods)

  • Food

    • Agricultural Resilience

    • Higher Nutrition

    • Sources and Food Security

  • Health

    • Traditional and Modern Medicine

    • Avoids spread from wildlife

    • Physical and Mental Health

  • Solutions to Climate Change

    • Water Cycle Sustainability

    • Improved Microclimates

    • Climate Adaptation

  • Cultural and Economic Value

    • Culture and Identity

    • Recreational

    • Energy

• Threats to Philippine Biodiversity

  • Indiscriminate Logging

    • The damage to the country’s forest areas and the biodiversity is estimated to be 2.1% (100,000 ha) a year in forest cover during the period 2000-2005

    • The second fastest in Southeast Asia (next to Myanmar) and the 7th fastest in the world

  • Indiscriminate Mining Operations

    • The country’s Mining Code led to the heavy influx of mining activity and investment

    • As of 2007, some 124 Mineral Production Sharing Agreements (MPSA) and around 4 Financial and Technical Assistance Agreements (FTAAs) has been issued

  • Increasing Human Population

    • Annual Population Growth Rate: 2.04%

    • Conversion of forests and coastal areas into agricultural land and settlements

  • Over-harvesting of Resources (Resources used for food, for ornamental and medicinal purposes)

  • Infrastructure Development (Road networks, irrigation, water resources, power and energy projects affect biodiversity directly and indirectly)

• IUCN (The International Union for the Conservation of Nature)

  • World’s most comprehensive information source on the global extinction risk status of animal, fungus and plant species

  • Ranking of Species

    • Data Deficient (inadequate information to make an assessment of its risk of extinction)

    • Least Concern

    • Near Threatened

    • Vulnerable

    • Endangered

    • Critically Endangered

    • Extinct in the Wild (species known to survive only in cultivation/captivity)

    • Extinct (there is no doubt that the last individual has died)