Message of Ecology

Population Growth Models 1. Exponential population growth model        In the exponential growth model, population increase over time is a result of the number of individuals available to reproduce without regard to resource limits. In exponential growth, the population size increases at an exponential rate over time, continuing upward as shown in this figure. The line, or curve, you see in the figure shows how quickly a population can grow when it doesn’t face any limiting resources. The line creates a shape like the letter J and is sometimes called a J-curve. Scientists often describe models with equations. The exponential growth model equation looks like this: dN/dt = rN       The symbols in this equation represent concepts. Here’s how to translate the equation into words: The change (d) in number of individuals (N) over a change (d) in time (t) equals the rate of increase (r) in number of individuals (N). 2. Logistic population growth model       In reali

 Mark Capture-Recapture Method               Mark and recapture is a method commonly used in eco l ogy to estimate an animal population 's size. A portion of the population is captured, marked, and released. Later, another portion is captured and the number of marked individuals within the sample is counted. Since the number of marked individuals within the second sample should be proportional to the number of marked individuals in the whole population, an estimate of the total population size can be obtained by dividing the number of marked individuals by the proportion of marked individuals in the second sample. The method is most useful when it is not practical to count all the individuals in the population.              It is assumed that all individuals have the same probability of being captured in the second sample, regardless of whether they were previously captured in the first sample (with only two samples, this assumption cannot be tested directly). This

RELUNG MULTIDIMENSI          Any developing condition or resource that can be used in a single axis or dimension, where dimensions can be explained as placement where the organism will be. Given the number of dimensions at the same time, a clear picture of the niche of an organism can be seen. For example, the temperature range in which chaffinch birds tolerate will overlap with many other species. Also, if we consider the size of the prey and the height of the foraging as the next dimension. To change any dimension of a resource or condition that affects the organism, it produces a clearly illustrated ecological niche - a 'n-dimensional hypervolume' (where n is the number of axes). Simple theories such as these clearly illustrated niches are 'unique' to each species (or even at one level of life of the species), although previous research shows this trend does not occur in a dynamic or limited (patchwork) environment. The practical weakness of the hypervolume

HABITAT AND MICROHABITAT                A habitat is an ecological or environmental area that is inhabited by a particular species of animal , plant , or other type of organism . The term typically refers to the zone in which the organism lives and where it can find food, shelter, protection and mates for reproduction. It is the natural environment in which an organism lives, or the physical environment that surrounds a species population . A habitat is made up of physical factors such as soil , moisture , range of temperature , and light intensity as well as biotic factors such as the availability of food and the presence or absence of predators . And micohabitat is   the small part of habitat, the precise location within a habitat where a species is normally found.

TOLERANCE RANGE Different species are found in different areas; some species have overlapping ranges, others do not. Each species has a set of environmental conditions within which it can best survive and reproduce. Not surprisingly, those conditions are the ones for which it is best adapted. Many different physical, abiotic (non- living) factors influence where species live, including temperature, humidity, soil chemistry, pH, salinity and oxygen levels. Just as species have geographic ranges, they also have tolerance ranges for the abiotic environmental conditions. In other words, they can tolerate (or survive within) a certain range of a particular factor, but cannot survive if there is too much or too little of the factor. Take temperature, for example. Polar bears survive very well in low temperatures, but would die from overheating in the tropics.  In example : Fish have a certain tolerance temperature and have different preference temperatures, depending on the