Ecosystems and Biological Interactions Flashcards
Defining Species and Biological Classification
A species is defined as a group of animals or plants that are capable of breeding with one another to produce fertile offspring. This biological classification is deeply rooted in the genetic makeup of the organisms, involving DNA and genes, which determine the specific characteristics of the individuals. Within plant cells, several key structures are essential for their function and classification, including chloroplasts, the nucleus, the cell wall, and the vacuole.
Scientific classification follows a hierarchical structure to categorize life on Earth. This hierarchy begins at the broadest level and moves toward the most specific. The levels of classification are Kingdom, Phylum, Class, Order, Family, Genus, and finally Species. This system allows scientists to precisely identify and group organisms based on shared physical and genetic traits.
Ecological Levels of Organization and Environmental Factors
Ecological studies organize the natural world into distinct levels of complexity. An individual organism is the basic unit, and a group of individuals belonging to the same species living in a specific area is referred to as a population. When multiple populations of different species live together in the same area, they form a community. An ecosystem is a broader level of organization that encompasses all the living organisms (the community) in an area along with the environmental conditions or abiotic factors that influence them.
Environmental factors that affect ecosystems are categorized as either biotic or abiotic. Biotic factors are living components that impact an organism, such as diseases, predators, and the availability of food. Abiotic factors are non-living environmental conditions that determine the survival of organisms; these include soil pH, temperature, light intensity, and moisture levels. The specific area where an organism lives within its ecosystem is known as its habitat.
Energy Transfer and Trophic Levels in Food Webs
Energy in an ecosystem flows through food chains and food webs, which illustrate the transfer of energy from one organism to another. All energy in these systems ultimately originates from the Sun, which producers, such as plants, use to create energy through the process of photosynthesis. A food chain represents a linear sequence of energy transfer, while a food web is complex and contains many interconnected food chains.
Organisms within a food chain are classified into different trophic levels. At the base are the Producers (plants), such as lettuce. These are consumed by Primary Consumers (herbivores), such as slugs or rabbits. Secondary Consumers (carnivores or omnivores) eat the primary consumers; for example, a hedgehog might eat a slug. Tertiary Consumers, such as a fox, eat the secondary consumers. At the very top of the food chain is the Apex Predator, which has no natural predators of its own. An example chain provided is Lettuce to Slug to Hedgehog to Fox.
Pyramids of Number and Biomass
Ecologists use pyramids to represent the distribution of organisms and energy within a food chain. A Pyramid of Number shows the actual count of individuals at each level. For instance, a chain might include lettuces supporting rabbits, which in turn support fox. These pyramids do not always take the traditional shape if the producer is a single large organism like a tree.
Biomass refers to the mass of living material in a population or community, typically measured in grams () or kilograms (). A Pyramid of Biomass represents the total mass of organisms at each trophic level and almost always maintains a pyramid shape because energy and mass are lost at each level of the chain. For example, a biomass pyramid might consist of a large Oak tree at the base, followed by lace wings, then hectic blue wings, and finally a sparrowhawk at the top.
Adaptations and Population Dynamics of Predators and Prey
Predators and prey have evolved specific characteristics to survive. Predators are often stealthy and quick, possessing strong legs for chasing. They typically have big, sharp teeth and forward-facing eyes to provide depth perception for hunting. Camouflage is also a common trait to aid in stalking prey and good hearing allows them to detect movement. High-level examples of predators include owls, mice (which can act as predators to insects), and cats.
Prey species exhibit different adaptations aimed at avoiding detection and capture. They often have eyes on the sides of their heads to provide a wide field of view, sometimes reaching degree vision. Like predators, they use camouflage for protection and have acute hearing. Some prey species also use bright colors to mimic toxic animals to ward off attackers. Examples of prey include caterpillars and mice.
The relationship between predator and prey populations is dynamic. Generally, at the beginning of a cycle, as time increases, the number of prey increases. As the number of prey increases, there is more food available for predators, so the number of predators also increases. This increase in predators eventually causes the number of prey to decrease because more of them are being eaten. This cycle causes both populations to fluctuate over time.
Chemical Controls and Ecosystem Disruption
In agricultural settings, a pest is defined as any organism that reduces the yield of a crop for the farmer. To combat this, farmers use pesticides, which are chemicals used to kill any animals or plants that could reduce crop yields. While effective at protecting crops, pesticides can cause significant disruption to ecosystems. If an ecosystem is disrupted, for instance by the removal of a predator, the prey population might grow too large (being "strong and happy" and having many offspring), leading to overconsumption of resources at lower trophic levels.
A specific type of pesticide is the insecticide, which is a chemical designed specifically to kill insect pests. However, insecticides can cause problems because they may disrupt the food chain and kill non-pest species, such as pollinators. If the number of insects in a habitat is reduced, there is less pollination, leading to fewer fruits growing. This results in a decrease in primary consumers, which then leads to less food for secondary consumers, causing the entire population to decrease.
Bioaccumulation and Biological Pest Control
Bioaccumulation is a major consequence of using certain chemicals in the environment. It is the build-up of toxic pesticides within the food chain. Because persistent chemicals do not break down easily, they are passed from one trophic level to the next. By the time the chemical reaches the apex predator, it has reached its highest concentration. This can lead to the apex predator being poisoned or becoming unable to reproduce. Furthermore, these toxins could enter the human food chain and cause illness.
As an alternative to chemical pesticides, some farmers use biological pest control. This method involves using natural predators to kill pests instead of chemicals. A common example of biological control is using ladybugs to manage pest populations naturally. This avoids the introduction of toxic chemicals and the risks associated with bioaccumulation.
Defining and Preserving Biodiversity
Biodiversity is defined as the number of different species within a specific area or room. High biodiversity indicates a wide variety of species, while low biodiversity indicates few species. Maintaining high biodiversity is crucial for several reasons: it provides sources for medicines, a steady food supply, building materials, and contributes to human mental wellbeing. Furthermore, biodiverse systems are generally more stable ecosystems.
There are several threats to biodiversity, including overhunting, the introduction of new diseases, pollution, climate change, and deforestation. To combat these threats, various conservation measures can be implemented. These include creating protected reserves (like nature reserves), establishing breeding programs for endangered species, maintaining seed and gene banks to preserve genetic diversity, and promoting education and ecotourism to raise awareness and provide economic incentives for conservation.
Questions & Discussion
Question 1: What happens when an ecosystem is disrupted? Response: If a predator is removed, the prey would grow strong and happy and have many children (offspring), leading to an increase in their population which may then over-consume the levels below them.
Question 2: What are the consequences of bioaccumulation? Response: The apex predator can be poisoned or lose the ability to produce (reproduce). Additionally, it could enter the human food chain, causing people to get ill.
Question 3: What are the problems with insecticides? Response: They can disrupt the food chain and kill non-pest species. If we reduce the number of insects, there is less pollination, leading to less fruit and a decrease in primary and secondary consumers.
Question 4: How do predators and prey interact? Response: Predators have adaptations like forward-facing eyes and sharp teeth, while prey have adaptations like eyes on the sides of their heads. Their population numbers fluctuate in cycles where an increase in prey leads to an increase in predators, which then leads to a decrease in prey.