Ecology and Population Dynamics Quiz

Ecology Definition

• Ecology is derived from two Greek words:
  • Oikos: meaning "home" or "house"
  • Logy: meaning "the study of"
• Ecology is literally "the study of an organism in its natural home."
• The term was coined by a German zoologist, Ernst Haeckel, in 1869 as Oekologie.
• It refers to the total relationship of an animal to its organic and inorganic environment.
• Several definitions have been proposed since.

Alternative Definitions

• Frederick Clements (1916): Ecology is the science of community.
• Charles Elton (1927): Ecology is scientific natural history focused on the sociology and economics of animals.
• Taylor (1936): Ecology is the science of the relations of all organisms to all their environments.
• Andrewaetha (1961): Ecology is the study of organism distribution and abundance.
• Kendeigh (1974): Ecology examines animals and plants in their relations to each other and their environment.
• Kinako (1988): Ecology examines the interrelationships between organisms and their biotic and abiotic environment through qualitative and quantitative analysis.

Unifying Factor

• The uniting factor in these definitions is that ecology studies the relationship between organisms and their environment.
• This encompasses the relationships between organisms and between organisms and their environment.

Distribution and Abundance

• Distribution refers to where organisms are found geographically, in terms of habitat, and spatially within a habitat.
• Abundance refers to the number of organisms present. Questions about abundance include whether a species occurs in multiple habitats and if there are many individuals of a species in a given habitat. Abundance can also be considered in relation to species rather than individual organisms.

Interactions

• Interactions refer to the relationships between an organism or species and aspects of its environment.
• The environment includes surroundings, which are generally categorised as biotic and abiotic factors.

Biotic Factors

• Biotic factors are other organisms and their organic products that interact with an organism or species.
  • Includes species that produce food for an organism
  • Species that feed on and harm an organism, including:
    • Predators: Species that kill and eat prey, with no long-term relationship.
    • Parasites: Species that live on or in a host and harm over a long period, but are unlikely to directly kill the host.
    • Parasitoids: Species laying eggs on a host, often insects, leading to eventual host death.
    • Brood Parasites: Species laying eggs in the nests of other species, harming the host's offspring.
    • Mutualists: Species whose presence is beneficial or essential to an organism and vice versa.

Abiotic Factors

• Abiotic factors are non-living elements in an environment that affect an organism, such as oxygen, water, pH, salinity, and temperature.

Ecology as Part of Biology

• Ecology is a part of biology, examining living systems at levels from organism to population to community to ecosystem, and biosphere.

Practical Applications

• Ecology involves measuring factors affecting the environment.
• Studying the distribution of living organisms and how they depend on each other and their non-living environment.

Explanatory Scope of Ecology

• Life processes and adaptations
• Distribution and abundance of organisms
• Movement of materials and energy in living communities
• Successional development of ecosystems
• Abundance and distribution of biodiversity

Subdivisions of Ecology

• Ecology is broadly divided into:
  • Autecology: The study of a single species, often encompassing life history, population dynamics, behavior, and home range.
• Synecology: The study of multiple species in a community, or entire ecosystems. This can include studies of deserts, caves, or tropical forests, focusing on energy flow and material movement through the system.
• Specialized Branches: Various specialised branches, with examples like habitat ecology, community ecology, population ecology, evolutionary ecology, taxonomic ecology, human ecology, applied ecology, production ecology, paleoecology, space ecology, and radiation ecology.

Scope of Ecology

• Wide range of applications
• Range, forest, and game management
• Agriculture, livestock, fish culture
• Conservation of land, products like minerals, soil, vegetation, and water.
• Space ecology
• Growing population problems
• Pollution
• Urbanization, town planning, and disaster mitigation

Levels of Organization in Ecology

• Organism: Fundamental unit of ecology, performing life processes independently.
• Population: Group of individuals of a single species in a specific geographical area. Factors affecting population size and genetic composition are studied. Different areas are considered in local populations and sister populations. Variation is measured through population size and population density at a given period
• Community: Association of interacting species in a particular area, analyzing how interactions shape community structure and organization.
• Ecosystem: Biological community plus abiotic factors influencing it. Focuses on entire ecosystems, including responses to abiotic components and large-scale topics like energy and nutrient cycling.
• Biosphere: Aggregation of all ecosystems comprising the whole earth's living zone.

Ecological Hierarchy

• Organism - fundamental unit of life.

  • characteristics of an organism:
    • performs all life processes independently.
    • a quantitative unit that has the ability to grow and regenerate.
    • resembles its parents and has a definite life span
    • ensures continuity of its race through transmission of characters to its offspring though reproduction.
    • cannot live in isolation showing interdependence with other biotic and abiotic factors of environment.

• Population - the next level in ecological hierarchy the word population has its origin in the Latin word populus meaning 'people'.

  • characteristics of populations: -Individuals living in the same area are called local populations. -Individuals share similar ecological processes at particular stages of their life cycles.
    • Similar populations of one species across different areas are known as sister populations. -Population a dynamic unit - number of individuals may increase or decrease due to factors such as birth rate, death rate, migration etc. -Population is measured using size and population density at a particular time. Populations are divisible into sub-groups called demes. A deme is a local population of closely related interbreeding species. Sexual communication more likely within the same deme.

• Factors affecting populations: Factors including birth rate (natality rates), death rate (mortality rate), age distribution, immigration, and emigration will affect populations.

Community

• Group of organisms of different species living together in a common environment.
  • Characteristics include Composition (species list) and Diversity (number and relative abundance of species)

Interactions in Communities

• Predation: One organism (predator) feeds on another (prey)

• Predation Defense Mechanisms:

  • Structures: Sharp spines, pointed leaves, poisons
  • Camouflage: Blending with surroundings
  • Harmful/Fright: Structures that harm predator
  • Flocking: Cooperative defense strategies
  • Mimicry: Mimicking another organism with a predator defense

• Commensalism: A symbiotic relationship where one species benefits while the other is neither harmed nor benefitted.

• Parasitism: An obligatory relationship where a parasite derives nourishment from a host, often harming it.

Symbiosis/Mutualism

• Symbiosis is a relationship in which both members of the association benefit.
  • Example, bacteria in the human intestinal tract provide vitamins.

Ecosystem

• Ecosystem is defined as a place or natural unit where organisms interact among themselves and their physical and chemical environment.
• Characterized by energy flow and chemical cycling.
• Populations are classified into feeding levels (trophic levels).

Trophic Levels/Feeding Groups

• Autotrophs: Producers, requiring only inorganic nutrients and an outside energy source to create organic compounds.
  • Chemoautotrophs: Bacterial producers that obtain energy from oxidizing inorganic compounds.
  • Photoautotrophs: Photosynthetic producers (e.g., algae and green plants), crucial for organic nutrient production in the biosphere.
• Heterotrophs: Consumers, needing pre-formed organic nutrients.
  • Herbivores: Feed directly on plants or algae.
  • Carnivores: Feed on other animals.
  • Omnivores: Feed on both plants and animals.
  • Detritivores/Decomposers: Organisms feeding on detritus (decomposing organic matter); examples include maggots, termites, and earthworms; also non-photosynthetic bacteria and fungi (e.g., mushrooms).

Biosphere

• The biosphere is the earth's thin zone of air, soil, and water that supports life.

Aquatic Habitat

• Classified into: freshwater, marine, and brackish.

• Salinity is the basis of category order.

• Freshwater habitats have low salt content (< 0.5 parts per thousand), compared to marine environments with higher salinity (> 30 parts per thousand)

  • Ecological factors are crucial in freshwater systems such as temperature, transparency, currents and biogenic salts (nitrates and phosphates).

• Marine habitats

  • Include oceans and seas; the largest ecosystem.
    • Features include great size and depth, covering a large portion of Earth's surface, including large and fluctuating waves, tides, currents, and dissolved nutrient concentration.

• Brackish water

  • A transition zone between freshwater and saltwater; often found where rivers meet the sea (estuaries).
    • Characteristics like fluctuating salinity, and abundant siltation make it a unique habitat with plant life and a significant fishery industry.

Terrestrial Habitat/Biomes

• Terrestrial communities are categorized into biomes distinguished by the dominant species.

• Key characteristic is vegetation type.

• Biomes include Tundra, Taiga, temperate deciduous forests, grasslands and deserts

  • Tundra is a biome characterized by permanently frozen subsoil (permafrost) and low rainfall. The dominant vegetation includes moss, grasses, and small perennials.
  • Taiga, a Russian term meaning "swampy forest," is dominated by coniferous forests; the soil is different in type than in the deciduous forests further south.
  • Temperate deciduous forests: Forests with a significant amount of rainfall and milder climates, with diverse populations of mammals, birds, insects. These have soils rich in nutrients.
  • Grasslands: Characterized by low rainfall and high evaporation, with vast open areas of grass or prairie. Carnivores are abundant here, with vegetation like tallgrass prairies and shortgrass prairies in North America, steppe in Eurasia, and veld in Africa. -Deserts are areas with less than 10 inches of rainfall per year. The lack of moisture is the primary shaping factor. Examples include Antarctic, Sahara, Arabian, Gobi, Patagonia, and Atacama.

• Tropical rainforests: characterized by high temperatures and abundant rainfall, containing a significant amount of plant and animal diversity, but typically having thin, nutrient-poor soil.

Test your knowledge of ecology with this quiz focused on ecosystems, the biosphere, and population dynamics. Explore essential attributes of organisms and distinctions between types of populations within ecological hierarchies. Challenge yourself with questions that assess your understanding of these fundamental concepts.