Introduction to Ecology

• Ecology examines the interactions between living organisms and their environments.
• Ernst Haeckel coined the term "ecology" from the Latin words "Oikos" (home) and "Logos" (study of).
• Ecology studies the interrelationships and interactions of biotic and abiotic components.
• Biological species reproduce and produce fertile offspring in nature; organisms unable to do this naturally are different species.
• Local populations of species are partially isolated by barriers, reducing gene flow but not cutting it off.
• Multiple species populations living and interacting form a community.
• A community of organisms and their physical/chemical environment make up an ecosystem.
• The environment is a complex of factors like light, temperature, soil, and water surrounding an organism.
• External forces, substances, or conditions affecting an organism's life are environmental factors.
• Ecological factors can be biotic (living) or abiotic (non-living).
• A habitat is a place where an organism lives; it presents a specific set of environmental conditions.
• Ecologists recognize four categories of ecological factors: climatic, topographic, edaphic, and biotic.

Climatic or Aerial Factors

• Light
• Temperature of air
• Rainfall
• Humidity of air
• Atmosphere (gases and wind)

Topographic or Physiographic Factors

• Factors related to the Earth's physical geography.
• Altitude
• Direction of mountain chains and valleys
• Steepness and exposure of slopes

Edaphic Factors

• Factors deal with the formation of soil.
• Physical and chemical properties of soil.

Biotic Factors

• Interactions between different life forms, including plants, animals, and microorganisms.

Physical Environment

• An organism's life is affected by the total sum of all ecological factors, with factors being interrelated.
• An increase in temperature would decrease humidity values, increased light affects photosynthesis rate and humidity.
• Ecological factors naturally operate in conjunction with each other.
• Studying factors separately helps understand and measure each effect.

Climatic Factors

• Climate is determined by humidity, temperature, wind pressures, and evaporation rates.
• Climate characterizes a particular region.

Light Factor

• Light species development of vegetation.
• Only 2-3% of solar energy is used in Primary Productivity.
• Factors like atmospheric water layers affect light intensity.

Light on Plants

• Light affects the growth, metabolism, development, and distribution of plants.
• Chlorophyll synthesis occurs only in the presence of light.
• The chlorophyll amount decreases in prolonged darkness.
• Sunlit leaves have more chloroplasts aligned with light direction.
• Shaded leaves have fewer chloroplasts arranged at right angles to light rays.
• Photosynthesis converts solar energy into chemical energy using carbon dioxide and water.
• Photosynthesis rate increases with light intensity.
• Compensation intensity is when photosynthesis balances respiration.
• Respiration, the oxidation of carbohydrates into carbon dioxide and water, increases at higher light intensity.
• Light increases the rate of transpiration
• Light limits the synthesis of auxins or growth hormones.
• Light intensity impacts on the development of flowers, fruits, and vegetative parts.
• Intense light favors flower, fruit, and seed development, while lower intensity promotes vegetative parts.
• Intense light helps form anthocyanin pigments.
• Movement of plants modulated by sunlight is called phototropism or heliotropism.
• Stem elongation towards light is positive phototropism; root movement away from light is negative phototropism.
• Response of plants to relative day length (photoperiod) is photoperiodism.
• Long Day Plants (LDP) bloom with light duration greater than 12 hours.
• Short Day Plants (SDP) bloom with light duration lesser than 12 hours.
• Day Neutral Plants (DNP) show little response to day length.
• Red light induces seed germination, blue light promotes germination.
• Far-red light inhibits seed germination.
• Duration and intensity determine plant distribution, and different regions have different vegetations.
• Light controls seedling development; dark conditions yield non-green, elongated seedlings with poor root systems; light makes it normal.

Light on Animals

• Light affects growth, development, reproduction, locomotion, and pigmentation.
• Metabolism rate is influenced by light intensity, higher intensity raising enzyme activity.
• Cave-dwelling animals are not influenced by intensity.
• Breeding activities are induced by light action over the gonads in some animals and birds.
• Relationship between day length and egg laying.
• Light affects development, accelerating it in some animals and retarding it in others.
• Light induces pigment formation, higher intensity resulting in higher pigmentation, influencing darker skin tones in tropical regions.
• Light controls locomotion speed in some lower animals, known as photo kinesis.
• Phototaxis: movement in response to light stimulus.
• Positive photoactic moves towards light source.
• Negative photoactic moves away from light source.
• Phototropism: responsive movement to light stimulus.
• Photophase is animal response to day length or light/dark rhythms; scatophase is portion of darkness.
• Eye development depends on light intensity; cave dwellers and deep-sea fishes have absent or rudimentary eyes.
• Light affects food preparation by photosynthesis, morphology, growth, metabolism, reproductive behavior, and survival.

Temperature Factor

• Temperature measures heat.
• Radiant energy is converted into heat.
• Heat is measured in calories.
• Optimum temperature is when physiological processes are most efficient.
• Minimum, optimum, and maximum temperatures are cardinal temperatures, varying by species and individual part.

Temperature on Plants and Animals

• Temperature impacts structure, physiology, growth, and distribution.
• Protoplasm may freeze at low temperatures or coagulate at high temperatures.
• Metabolic activities are carried out in the presence of various enzymes.
• Metabolic activities are increased with a temperature rising, but may decrease with higher increase.

Temperature on Respiration

• Van't Hoff's law says the respiration rate usually doubles (Q10=2) with a 10°C rise in temperature in poikilothermic animals.

Temperature on Development

• Temperature influences plants and eggs and larvae development in poikilothermic animals
• Hot climates lead to higher development eggs and larvae rates compared to cold climates in poikilotherm animals.

Temperature on Growth

• Poikilothermic invertebrates increase their temperature when temperature increases.
• Seedlings of plants exhibit elongation of the hypocotyl when there is a temperature increase.

Temperature on Transpiration

• Transpiration, loses water, increases with atmospheric temperature.

Temperature on Reproduction

• Maturation of gonad and gametogenesis need specific temperature which varies from species to species.
• Animals have different breeding periods due to temperature effects.

Temperature on Sex-ratio

• Temperature determines in the sex-ratio in the poikilothermic animal population.

Temperature on Body Size

• Animal body size and extremity length relates differently over different geographic areas of temperature.
• Bergmann's rule increases in average body mass of animal populations with latitude increase, conserving heat because smaller surface area to volume ratio.
• Allen's rule has closely related endothermic vertebrates adapting to cold temperature have shorter appendages.
• Bird races with narrow wings occur in colder regions, wings tend to be broader in warmer areas Rensch's rule.
• Jordan's Rule says that fishes living in low temperature water regions tend to have number of vestibule than those living in the high temperature water regions.

Temperature on Coloration

• Glogger's Rule says body color of animals influenced by temperature.
• Birds and mammals living in humid climates have darker pigmentation.

Temperature on Distribution

• Temperature influences distribution due to its effect on biological processes and bodies regulating temperatures.
• Coral reef formation is limited to 20°C isotherm.
• Ectotherms rely on external heat; endotherms generate internal heat.
• Homeotherms maintain narrow internal temperature; heterotherms' body temperature varies.
• Exceptions exist, hibernating mammals lower body temperature, becoming heterothermic.
• Deep-water fish are like homeotherms, because water temperature is constant.
• Body temperature of heterotherms vary in different environments as homeotherms remain constant.

Thermoregulation in Homeotherms

• Skin plays a role in Homeotherm.
• Each skin structure present in temperature regulation.
• Homolotherm have different response to cold or heat.

Response to cold

• Subcutaneous fat- serves as insulator.
• Air trapped between hair.
• Skin constrict, blood directed to deeper layers.
• Heat generated by muscles.
• Countercurrent heat exchange systems body heat .
• Small species can be limited by cold temperatures.

Response to heat

• Animals of climates little subcutaneous fat.

• Fat is stored only in located areas in animals.

• Hair lowered; no space between hair.

• Vessels dilated; blood loss heat to atmosphere.

• Rate in muscles reduced sweat.

• Hypothalmic temperature centre.

Thermoregulation in poikilotherms

• Poikilotherms stress from environment.

• Insects enter arrested growth.

• Conditions cause environmental Amphibians extreme

• Temperature is raised the temperature.

• Basking sideways in sun.

• Lower temperature is though evaporation skin.

• Many plants ground.

• Low regions have distributions.

Effect of high temperatures on distribution

• Internal temperatures

• Amounts of heat increase shock stress.

• Proteins damaged.

• Hsp is extreme.

• Spores resistance.

Water:

• Water production important.

• Humans are important importance.

• Water has soil protoplasm.

Water in plants and animals.

• Large hydrophyte water.

• Xerophytes are less water.

• Moderately mesophyte is water.

• Hydrocholes.

• Large water- xerocoles long.

• Requirements dry quantity is.

Rainfall:

• Water precipitation is major.

• Water animal interchange.

• Annual rainfall.

Wind:

• Wind moves vital air.

• Wind breaks in deformation.

Humidity:

• High affects and vapour humidity.

Atmospheric Gases:

• Important atmospheric etc gases.

Fire Factor

• Most fires very rare in areas.

Effects of fire

• Some trees killed by fire

• Fire can changes in light as soil.

• Plants more tolerant.

• stimulated are to grassfire

Edaphic Factors:

• Chemical features are soil

Formation of Soil:

• Weathering two development.

Weathering:

• Weathering long powder.

Maturation:

• The structure of the major

Melanization:

• Become mixed humus.

Podzolization:

• Temperature minerals low Rainfall.

Gleization:

water continuously mineral.

Patternisation:

and Combination rate matter Hot Combination

Soil types:

• Coiluvial.

• Alluvial.

• Qlacial snow.

• Eolian the classification combination made.

Soil Conservation:

Topographic Factors:

• Microclimate geographic a factors, vegetation factor topography

• Sea level happens pressure with altitude.

Direction factor Slopes

• vegetation in

Chain factor

mountain Chains: influence

Biotic Environment

Interactions Direct Biotic factors and that

Symbiosis biotic Environment

living Factors that that

Combinations: that

growth other detailed interaction detailed other Combination