Biology Ecosystem an Ecosystem Essay

Biology Ecosystem an Ecosystem Essay Biology: Ecosystem an Ecosystem Essay Ecosystem An ecosystem includes all of the living things (plants, animals and organisms) in a given area, interacting with each other, and also with their non-living environments (weather, earth, sun, soil, climate, atmosphere).In an ecosystem, each organism has its’ own role to play. Usually, biotic members of an ecosystem, together with their abiotic factors depend on each other. This means the absence of one member, or one abiotic factor can affect all parties of the ecosystem. A new organism or physical factor, can distort the natural balance of the interaction and potentially harm or destroy the ecosystem. As ecosystems are defined by the network of interactions among organisms, and between organisms and their environment, they can be of any size but usually encompass specific, limited spaces. Biomes Biomes are very large areas on the earth’s surface, with animals and plants adapting to their environment. Biomes are often defined by abiotic factors such as climate, relief, geology, soils and vegetation. A biome is NOT an ecosystem. If you take a closer look, you will notice that different plants or animals in a biome have similar adaptations that make it possible for them to exist in that area. There are many major biomes on earth. Different Types of Biome:- 1. Desert:-The Sahara Desert is the world’s largest desert, located in North Africa. Very hot and dry with very little rain. 2. Tropical Forests:- Found near the equator in Central and South America, parts of Africa and Asia. Hot, humid with equatorial climate and biggest biodiversity. Almost half of the world’s species (plants and animals) live there. The trees are mostly hardwood. 3. Savannah:- Found in Central Africa (Kenya, Zambia, Tanzania), northern Australia and central South America (Venezuela and Brazil). Hot and dry, mainly grass, scrub and occasional trees. This biome has two distinct seasons - a dry season and a rainy season. During the dry season the vegetation dies and re-appears rapidly during the rainy season. 4. Mediterranean:-Found in Mediterranean Sea, near Cape Town in South Africa and Melbourne in Australia. The climate of this biome is not too hot or cold. 5. Temperate Grasslands:- Mainly found in the Puszta in Hungary, the Veldt in South Africa, the Pampas in Argentina and the Prairies in the USA. Many grass and trees with little large bushes. Climates are temperate continental with mild weather and moderate rainfall. 6. Temperate deciduous Forest:- Found usually across Europe and USA contain trees that lose their leaves. These have a temperate maritime climate, usually with mild and wet weather. 7. Coniferous: Found in Scandinavia, Russia and Canada. Have Evergreen trees, cool climate with moderate rainfall. 8. Mountain:-These areas can be very cold at night and during winter. Trees usually do not grow at higher levels. About 80 per cent of our planet's fresh water originates in the mountains. 9. Tundra:- Surrounds the North and South poles. Extremely cold climate, temperatures often reaching about -50Â °F in the winter, supporting only a few plants and animals. Tundra covers about one-fifth of the Earth's land surface. Food Chains All living things need to feed to get energy to grow, move and reproduce. But what do these living things feed on? Smaller insects feed on green plants, and bigger animals feed on smaller ones and so on. This feeding relationship in an ecosystem is called a food chain. Food

Population Biology Basics

Population Biology Basics Populations are groups of individuals belonging to the same species that live in the same region at the same time. Populations, like individual organisms, have unique attributes such as growth rate, age structure, sex ratio, and mortality rate Populations change over time due to births, deaths, and the dispersal of individuals between separate populations. When resources are plentiful and environmental conditions appropriate, populations can increase rapidly. A populations ability to increase at its maximum rate under optimal conditions is called its biotic potential. Biotic potential is represented by the letter r when used in mathematical equations. Keeping the Population in Check In most instances, resources are not unlimited and environmental conditions are not optimal. Climate, food, habitat, water availability, and other factors keep population growth in check due to environmental resistance. The environment can only support a limited number of individuals in a population before some resource runs out or limits the survival of those individuals. The number of individuals that a particular habitat or environment can support is referred to as the carrying capacity. Carrying capacity is represented by the letter K when used in mathematical equations. Growth Characteristics Populations can sometimes be categorized by their growth characteristics. Species whose populations increase until they reach the carrying capacity of their environment and then level off are referred to as K-selected species. Species whose populations increase rapidly, often exponentially, quickly filling available environments, are referred to as r-selected species. Characteristics of K-selected species include: Late maturationFewer, larger youngLonger life spansMore parental careIntense competition for resources Characteristics of r-selected species include: Early maturationNumerous, smaller youngShorter lifespansLess parental careA little competition for resources Population Density Some environmental and biological factors can influence a population differently depending on its density. If population density is high, such factors become increasingly limiting on the success of the population. For example, if individuals are cramped in a small area, the disease may spread faster than it would if population density were low. Factors that are affected by population density are referred to as density-dependent factors. There are also densitys of density-independent factors might include a change in temperature such as an extraordinarily cold or dry winter. Intra-Specific Competition Another limiting factor on populations is intra-specific competition which occurs when individuals within a population compete with one another to obtain the same resources. Sometimes intra-specific competition is direct, for example when two individuals vie for the same food, or indirect, when one individuals action alters and possibly harms the environment of another individual. Populations of animals interact with each other and their environment in a variety of ways. One of the primary interactions a population has with its environment and other populations is due to feeding behavior. Types of Herbivores The consumption of plants as a food source is referred to as herbivory and the animals that do this consuming are called herbivores. There are different types of herbivores. Those that feed on grasses are referred to as grazers. Animals that eat leaves and other portions of woody plants are called browsers, while those that consume fruits, seeds, sap, and pollen are called frugivores. Predators and Prey Populations of carnivorous animals that feed on other organisms are called predators. The populations on which predators feed are called prey. Often, predator and prey populations cycle in a complex interaction. When prey resources are abundant, predator numbers increase until the prey resources wane. When prey numbers drop, predator numbers dwindle as well. If the environment provides adequate refuge and resources for prey, their numbers may again increase and the cycle begins again. Competing Species The concept of competitive exclusion suggests that two species that require identical resources cannot coexist in the same location. The reasoning behind this concept is that one of those two species will be better adapted to that environment and be more successful, to the point of excluding the lesser species from the environment. Yet we find that many species with similar requirements do coexist. Because the environment is varied, competing species can use resources in different ways when competition is intense, thus allowing space for one another. When two interacting species, for example, predator and prey, evolve together, they can influence the evolution of the other. This is referred to as coevolution. Sometimes coevolution results in two species that influence (both positively or negatively) from each other, in a relationship referred to as symbiosis. The various types of symbiosis include: Parasitism: One species (parasite) benefits more than the other species (host).Commensalism: One species benefits while a second species is neither helped nor injured.Mutualism: Both species benefit from the interaction.