Ecology Basics

• The lecture is for General Biology I, course code BIO 101
• The course lecturer is Dr. Emmanuela Onyinye Ibeh Ogar

Ecology

• It is derived from the Greek words "oikos" (meaning home) and "logos" (meaning the study of)
• It is the study of the relationships between living organisms and their environment
• Understanding ecology is important for humanity due to technology's ability to modify the environment

Classification of Ecology (Based on Study Area)

• Autecology studies an individual species' relationship with its environment; also called Species ecology
• Synecology studies communities, their composition, behavior, and relation with the environment; also called Ecology of communities

Classification of Ecology (Based on Study Environment or Habitat)

• Aquatic Ecology studies interaction of organisms in the water, and includes:
  • Marine water ecology: oceans, deep sea, estuaries
  • Freshwater Ecology:
    • Lotic (running water): rivers, streams, springs
    • Lentic (standing water): ponds, lakes
• Terrestrial Ecology studies interaction of organisms on land surfaces

Classification of Ecology (Based on Advancement)

• Population ecology focuses on the study of populations
• Community ecology focuses on the study of communities
• Ecosystem ecology focuses on the study of ecosystems
• Microbial ecology focuses on the study of microorganisms
• Pollution ecology focuses on the study of pollution

Levels of Ecological Organization (Smallest to Broadest)

• Organism/Species
• Population
• Community
• Ecosystem
• Biome
• Biosphere

Organism and Population

• Species: A group of living organisms consisting of similar individuals capable of interbreeding
• Population: A group of individuals of the same species living in the same area at the same time, that can interbreed and produce fertile offspring
• Organisms not in the same population cannot have fertile offspring
• A local population can occupy a small habitat like a puddle
• Example: All members of a monkey species on a large island

Community

• Organisms do not live randomly; they live in communities
• Community: Collections of different species living in the same area at the same time
• Example: Zebras and elephants living in the same area of Africa
• Interactions between organisms at the community level:
• Predator/prey relationships
• Consumer/producer relationships
• Competition and cooperation

Ecosystem

• It is a community of organisms together with its physical environment
• It is the community plus the abiotic factors in that environment
• An Ecosystem example would be Zebras and elephants, water, sunlight, soil and temperature in that environment

Biome

• A biome is a large geographic area classified by its plants and animals
• Major biome types include tundra (coldest), forest (rain forest, temperate, and taiga), grassland (savannah), and desert (driest)
• Biomes are defined by climate, rainfall/water characteristics, elevation, and plant characteristics

Biosphere

• It is the region on, above, and below the Earth's surface where organisms live; includes all Earth's ecosystems
• The biosphere includes the lithosphere, hydrosphere, and atmosphere
• Hydrosphere: the combined mass of water
• Atmosphere: protective layer of gases that shelters all life, maintaining temperatures and blocking harmful sunlight
• Lithosphere: the solid outer layer of Earth, including the crust and upper mantle

Habitat and Niches

• Habitat: The place where particular plants or animals live
• Niche: A species' functional role in a community
• The biosphere has three major types of habitats:
  • Terrestrial (Land):
    • Organisms live and move on land (terrestrial organisms)
    • Marked by rapid changes temperature, moisture and climate
    • Sustained by air, soil temperature, and rainfall
    • Includes trees, ferns, elephants, camel, man
  • Aquatic:
    • Organisms live in water (aquatic organisms)
    • Can be freshwater (rivers, ponds, lakes, streams) or marine (sea water)
    • Includes algae, small animals and fishes.
  • Aerial or Arboreal Habitats
    • Animals are tree dwelling (arboreal), e.g. monkeys and squirrels
    • Organisms use air (sky) for their activities, e.g. birds

Relationships and Interactions in an ecosystem

• Distribution and abundance of organisms are shaped by biotic and abiotic factors
• Abiotic Components: Nonliving chemical/physical factors affecting survival and reproduction (e.g., temperature, light, water, nutrients)
• Biotic Components: Living factors that directly or indirectly affect the environment (e.g., organisms, their presence, interactions, wastes)

Autotrophs and Heterotrophs

• The biotic component of an ecosystem consists of living organisms divided into two main groups:
  • Autotrophs:
    • Use sunlight or chemical energy to manufacture their own food
    • Primary food producers
    • Includes green plants, some bacteria (Cyanobacteria), and photosynthetic protists (Brown and Red Algae, Euglena)
  • Heterotrophs:
    • Cannot manufacture food
    • Feed on ready-made food from the tissues of organisms in their environment
    • May be consumers or decomposers -Includes all animals, carnivorous plants, fungi, and most protists and bacteria

Energy Flow in Ecosystems

• The sun is the ultimate energy source for almost every ecosystem
• Green plants make their own food from inorganic substances (producers)
• Plants die and are broken down by decomposers (organisms that acquire food from dead organic materials)
• Decomposers release some nutrients back, where they are available to producers
• Energy is not cycled, it is continuously lost from an ecosystem
  • Energy captured by producers is passed to organisms that eat them
  • Consumers (animals/organisms that eat plants or other animals) die and are broken bown by decomposers, or eaten by carnivores (secondary consumers)

Food Relationship

• All living organisms must obtain energy and nutrients from their environment
• Nature's feeding pathway:
  • Begins with a primary producer
  • The primary producer is eaten by a primary consumer
  • Primary consumer is eaten by a secondary consumer
  • Secondary consumer is consumed by the tertiary consumer
  • Decomposers convert the remains of dead producers and consumers

Trophic Level

• Trophic level: Each step along a feeding pathway, positions in a food chain or web.
• Energy and nutrients are transferred step by step among organisms along a feeding pathway
• Grassland example: a lion eats a zebra, that ate grass. the grass converted sunlight into chemical energy
• Consumers can feed at more than one level (e.g., humans eating vegetables, cows, or snakes)
• Energy is passed from one level to the next, with about 90% used up at each level for locomotion, heating, and reproduction
  • Animals at the second trophic level have about 10% of the energy available
  • Animals at the third level have only 1% of the energy available

Trophic Level Examples

• 1st Trophic Level: Producer
  • Gains Energy by making their own food
  • Example: Plants
• 2nd Trophic Level: Primary Consumer
  • Gains energy by consuming producers
  • Example: Mice eat plant seeds
• 3rd Trophic Level: Secondary Consumer
  • Gains energy by consuming primary consumers
  • Example: Snakes eat mice
• 4th Trophic Level: Tertiary Consumer
  • Gains energy by consuming secondary consumers
  • Example: Hawks eat snakes

Food Chains and Food Webs

• Diagrams that represent feeding relationships from producers to consumers to decomposers show who eats whom and model energy/matter flow through ecosystems
• Food Chains:
  • Represent the feeding pathway through which energy flows through an ecosystem
  • Show transfer of energy / nutrients from organisms to organisms in a pathway
  • Producers use energy from the sun to make food and start the chain
  • Arrows represent the direction of energy flow consumed to the receiver
  • Decomposers may feed on organisms at any stage and recycle nutrients
• Food Webs:
  • Represents multiple pathways through which energy and matter flow through an ecosystem
  • Includes many intersecting food chains
  • Demonstrates that organisms eat, and area aten, by than one species

Energy Pyramid

• It is a diagram that illustrates the relative amounts of energy within each trophic level
• It can be used to describe an ecosystem
• Where levels have:
  • Primary Producers 100%
  • Primary Consumers 10%
  • Secondary Consumers 1%
  • Third Level Consumers .1%
  • Apex Predators .01%
• Most of the energy in an energy pyramid is used or lost as heat energy at each tier up the pyramid
• Only 10% of the energy produced at a level is available to the one above it
• Producers are the foundation of all pyramids

Symbiosis

• Interaction between individuals of different biological species
• One organisms receives a benefit from the interaction and the other can receiving a benefit, be harmed or not be affected
• Three main symbiotic relationships:
• Commensalism: one organism benefits, the other is unaffected
• Mutualism: both organisms are benefited from each other
• Parasitism: one organism is benefited while the other organism is harmed

Types of Symbiosis

• Mutualism: both organisms benefit (e.g., coral reefs: coral organisms and algae residing inside them)
• Commensalism: one organism benefits, the other is neither helped nor harmed (e.g., hermit crabs using gastropod shells for protection)
• Parasitism: one organism benefits, the other is harmed (e.g., liver fluke attaching to the liver)

Additional Other Biological Relationships

• Amensalism:
• One species causes harm to another without benefit to itself (e.g., cattle trample grass)
• Competition: Organisms compete for the same resources (food, water, shelter, space, mate (e.g., goats and beetles feed on the same shrub)
• Antibiosis: One organism is damaged or killed by a chemical secretion of another (e.g., Penicillium mold creating penicillin, toxic to bacteria)
• Predator/Prey: predator hunts, kills, and eats prey
• Cooperation: organisms work together (e.g., wolf packs)

Population Ecology

• Groups of the same species living in the same area forms a population, population ecology studies a population's structure and how it changes
• In population studies, we investigate:
• Types of organisms
• Dominant species: one or a few species are dominant based on numbers or size, greatly influence the habitat is
• Population characteristics: size, frequency, density, percentage, cover distribution
  • Size: affects survival of a species, large populations resist dangers better
  • Density: average number of individuals per unit area, estimate = population size/area
  • Frequency: how often a species occurs at sites
  • Percentage cover: area of ground covered/occupied by a species
  • Distribution: arrangement of individuals - clumped, evenly spaced, or randomly spaced

Population Studies

• Since populations are always changing, estimate population by using sampling, a method scientists use quadrat
• Quadrat is a rectangular used on small, slow-moving plants, which is by placing it randomly in the ground and counting
  • to determine density do the following
  • Frequency of the species: the amount of times an organism is in the quadrat
  • Number of tosses/ throws: say, for example, 20 times
  • Average number of organisms per quadrat = Frequency/number of tosses (e.g., 100/20= 5)

Calculating Size/Density

• Population density = Average Frequency/Area of habitat
• Transect Method: Use a measuring tape and recording encountered plants at marked intervals to estimate number of plants
• Capture and recapture: -Capture, mark with paint and recapture mobile organisms -Animals of the same species are caught, counted (A1), marked and released -The next day the same number of animals are caught (A2) and recorded -The number of marked (A3) animals the day before is counted recorded
• The population is calculated by the formula: Population=A1* A2/A3

Investigating Animal Life

• Butterfly/sweep net: Capturing surface specimens
• Traps include attractants for capturing mammals and nocturnal animals
• Tullgren Funnel: Capturing soil using a wire gauze which dries out the contents and forces them into a collection container underneath
• Plankton Net: Collects tiny aquatic organisms as it slowly filters water
• Fish Trap: Traps many fishes swimming in the center
• Pooter: collecting small insects on trees by sucking through a mouth piece

Carrying Capacity

• Real world has limited resources
• The number of individuals that can be sustained by The environment is called Carrying Capacity
• Carrying Capacity: the maximum number of individuals that the environment an carry and sustain.

Factors Affecting Population Size

• It is dynamic so it's constantly changing
• Increase in population is generally related to:
• Birth Rate: The is an increase to the population
• Immigration: New comers increase the number of the species
• Abundance in food: animals are attracted to locations with lots of food, increasing the population.
• Factors that lead to decrease in population may include
• Death Rate: decrease in number of of animals leads to decrease in population size
• Emigration: individuals that are moving away from the range decrease it.
• Competition
• Disease Factors Affecting Ecosystem - pathogens, water and competition
• Pathogens lower the population
  • a disease multiply grows the population

Ecological Factors Affecting Pop Size

• Ecological factors are those factors in the environment which can influence living organisms or cause changes in any habitat.
• Include to aquatic species, salinity, density, waves,
• terrestrial species are relative humidity, rainfall, edaphics (soil factors)
• Most common factors across habitats that can influence living organisms may include - light, temperature, pressure, etc.

Biogeochemical Cycle

• Biogeochemical cycles are movement and transformation of certain elements through living organisms
• The term itself is derived from the breakdown; Bio (Biosphere), Geo (Geosphere), Chemical (moving elements)
• The earth obtains energy from the sun, all other elements is obtained in closed systems.

Biogeochemical Cycles

• Water Cycle: From the different water regions to the air through evaporation and back as rainfall, responsible for maintaining conditions

• Carbon Cycle: Carbon is exchanged through all green plants through carbon dixode during photosynthesis .

• This Carbon is thus stored in the plant. , when dead, they can transform into fossil fuels through the earth.

• When combusted it goes back into the atmosphere. Animals that consume these plants are also storing it, and decomposing it after is returned.

• Nitrogen Cycle: Converts into several forms throughout the envrionment.

• Is fixed by bacterias in root nodules in pants is made available to soil

• Convert this gas into ammonia and supply to fertilizers

• is turned back by into an atmosphere

Environmental Impacts (Natural and Human)

• Natural:
  • Volcanoes: Greenhouse Gases Increases temp
  • Fires: Beneficial and Harmful to the environment by either allowing new plants to grow and removing resources for animals
  • plants have mutiple benfits - erosion, improving air/ soil quality, etc
• Human:
  • Activities can change the balance
  • Hurt through pollution, resource
  • Introduce invasive However, also help by preserving and helping envrionment.

Heredity

• Refers to the passing through genes from generation
  • Genes are section of DNA that code for a certain charateristic
• Alleles: different versions of the same gene in a flavor/ variant
  • Example pea plant height
  • Genes: Specific Traits, Alleles which dictate the form it'll take
• traits which come in 2 (pair forms) - the term in genetics for this is called alleles

Heredity Definitions

• Homozygous – Each organism has two alleles for every gene (Each chromosome has one each). In homozygous, both the alleles are the same. For Example, “TT” is the homozygous expression for tallness trait.
• Heterozygous – If the two alleles are different from each other, then they are heterozygous in nature. For Example, "Tt" is the heterozygous expression for tallness trait.
• Chromosomes – These are thread-like structures made up of nucleic acids (DNA) and proteins. They are mostly found in the nucleus of the cells. They carry the hereditary or genetic information in the form of genes.

Gene Location

• Loci locations that have been in
  • Genotype: combination of alleles
• Phenotypes: the appreance of the organisms
• Gregor Mendel conducted research to see these

Gregor Mendel's studies

• He used pea plants to show inheritance
• He was able to observe patterns from gens and summarize under headings below Law of Dominance: hybrid offspring will only inherit the dominant trait,
• Segregation every dividual possess two and 1 is passed
• Independent Assortment: one pair of genetics inherits independendent of each

Monohybrid Cross

• A cross between organisms that have ONE pairing of characters for example cross a short and tall tea plant
  • In the first progeny for monohybrid plants result is 50 percent
  • Tall for all test
• In the second progeny the split but the short is expressed more
• For a plant to be tall only single part is needed, but in second both sides need to short for expression

dihybrid Cross

• Crossing across 2 to consider alterative
• pea plant with round and green
• heterozygous
• Parental, geno is need and test from the start and u should understand you self is just cross to itself.

Variation

• occurs in DNA copying , and heredity
• Sexual is where production creates gentic variation that can occur , it can happen
• Where one chromosome comes together duing meiosis, transfering each other and results new dna
• Meiosis is a combination and random, so the race will one win and transfer the info and be a result.
• Where in Miosis replication the chromosomes and split

Explore fundamental ecological concepts such as ecosystems, biomes, the ecosphere, and habitats. Learn about population dynamics, including density, frequency, and distribution patterns, alongside methods like quadrat sampling for ecological studies.