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Chapter 4:
The ecosystem is defined as within a given region; the variety of ecosystem exists.
Biodiversity or species diversity is generally regarded as the number of species present within a given region of various origins.
Species richness is regarded as the number of species present in a given area.
Species evenness is the measure through which we can determine whether a particular ecosystem is dominated by one species or the same number of species represents that specific region.
Evolution is defined as the change that occurs within the species’ genetic composition over a specific period of time.
Genes are present on the chromosomes within each cell of an organism.
Inherited traits are the codes by the genes which may or may not expressed in an organism physically.
The complete set of genes present in an individual is referred to as the genotype.
The collection of the genes within an organism are defined as the genome.
The mutation is defined as the change which occurs in the genetic code of an organism.
Phenotype is defined as the set of traits that are usually expressed physically or biochemically in an organism.
Evolution by artificial selection refers to the selection of the traits which can be passed to over the next generation and the selection of breeding by specific individuals.
In evolution by natural selection, the survival and reproduction of individuals are determined by the environment.
Adaptation is defined as those characteristics or traits which is responsible for the improved fitness in an organism.
Fitness is defined as that characteristic which helps the organism to survive.
The main points of the Charles Darwin theory are:
- An excess of off-springs can be produced by an individual.
- The survival of all off-springs is not possible.
- Traits are different in individuals.
- The variation in traits can transfer from one generation to another.
- The variation in traits is because of the variation in the ability of survival and reproduction.
Natural selection is the driving force for evolution.
Variation is the driving force for natural selection.
Mutation and sexual reproduction is the driving force for variation.
The factors affecting the pace of evolution include:
- The more slowly the rate of the environmental change, the better for evaluation.
- For evolution, the variation in the genetic amount is better.
- The population size which is involved is better for evaluation.
- The faster the generation time, the better is evolution.
The range of tolerances is those abiotic conditions under which the species perform best.
Realized niche is defined as those conditions, i.e., biotic or abiotic under which the species lives.
Niche generalist is defined as the wide range of conditions under which the species live.
Niche specialist is defined as those species which can survive only in specific conditions.
Fossils are the preserved organic material of an organism which is largely by minerals in rocks.
Within a short period of geological time, a large number of species became extinct, called mass extinction.
Humans are causing the sixth mass extinction.
The population is defined as the number of individuals who live in a particular area and are capable of interbreeding.
Community is defined as the various groups interacting with each other in a given area.
An ecosystem is defined as the interaction of the organism with each other and their physical environment.
Population size is defined as the number of individuals present within a defined area at a specified time.
Population density is defined as, at a specified time, the number of individuals presents per unit area.
Population distribution is defined as the distribution of individuals with respect to one another. Three types of population distribution are:
Density-dependent factors are those factors in which there is an influence of population size is present on the probability of the survival of the individual. For example:
- Soil nutrients and water are essential for terrestrial plants.
- Food, water, and nesting sites are important for animals.
Density independent factors are those factors in which there is no influence of population size on the probability of the survival of the individual—for example, fires, volcanoes, the temperature of the environment, and hurricanes.
Population growth models are the type of mathematical expressions which can be used to determine the size of the population present anywhere in time.
The growth rate is defined as the difference between the production of a number of individuals in a specified time and individuals’ death during the same time period.
The intrinsic growth rate is defined as the maximum potential for growth for a population under the ideal condition but with limited resources.
The rapid growth of the individuals, because the population is not limited by resources, leads to the formation of a J-shaped curve when the population’s size is graphed against time is defined as an exponential growth model.
Logistic growth is defined as the growth of a population exponentially but slows as the population.
The s-shaped appearance in the logistic growth model is defined as the S-shaped curve.
Carrying capacity is the limit basically, which determines the sustainability of the population when there are limited resources present. It is denoted by K.
Environmental resistance is defined as the pushing back or the slowdown of the growth of the population.
Overshoot is defined as the scarcity condition in which limited resources become unavailable, and the population will experience overshoot as they become larger compared to their capacity.
Die-off refers to the population crash, which occurs because of over-shoot.
K-selected species are those species that grow slowly until a time come, and they reach their carrying capacity.
R-selected species are those species that grows quickly and is followed by overshoots and die-offs.
Competition refers to the struggling of the individuals for the limited resources available.
The competitive exclusion principle is defined as the competition which cannot exist among two species for the same limiting resources.
Niche overlap is defined as the overlap which occurs when the same resources are utilized by two different species.
Resource partitioning is defined as the co-evolvement of the two species for the division of limited resource by adapting specific behaviour or form.
Mutualism is a type of symbiosis in which both organisms benefit from each other: corals, lichens and pollination.
Parasitism is a type in which one gets the benefit, but the host will get harm; examples are the cat and roundworm, human and lice, mosquitoes, and humans.
In commensalism, one is getting the benefit, and others got no benefit and neither harm—for example, frog and tree, deer and spider, cattle and egrets.
The animal that hunts and kills other animals for food is called predators, such as lion and deer, leopard and zebra, eagle, and snail.
Herbivores are animals that depend on plants to eat and make their food, for example, cow, goat, and sheep.
Parasites are those organisms that take their food from their host and harm them, an example, mosquito, lice, GIT worms.
Parasitoids are defined as
Keystone species have a disproportionately large effect on their natural environment relative to their abundance,
Alien species are living outside their native distributional range, arrived there by human activity, either deliberately or accidentally directly or maybe indirectly.
An invasive species is an organism that negatively alters its new environment. However, their spread can have good aspects.
Primary succession is an ecological succession that starts in virtually no life areas, such as regions in which there is soil not present or where the soil is incapable of sustaining life—examples: volcano eruption, soil erosion, land sliding.
After a significant disturbance, if plant and animal recolonized, secondary succession examples are fled, wildfire clear the forest.
Chapter 5:
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