The term “population” today is used in various fields and fields of science. It has the greatest influence in biology, demography, ecology, medicine, psychometrics, and cytology. But what is a population, and how is it characterized?
A population is a group of individuals of one species. Each of these organisms has a strictly limited and specific habitat. In other words, a population is a family of individuals that make up a particular biocenosis. For free-living forms, the boundary of distribution relative to the territory is due to such factors as relief, climate, etc. For parasitic organisms, the barrier to settlement is the fitness and life cycle.
To date, the study population mainly conducted to detect genetic or environmental sequences. This allows you to define the environment the survival of the species and their heredity. At the moment there is another concept – "cell population". This isolated the offspring of a specific number of groups of cells. The study of this sphere by specialists within Cytology. From the point of view of genetics, a population is a heterogeneous hereditary set of forms of one species, with which the so-called pure line is opposed. The fact is that each family of individuals responds to specific characteristics and represents a particular phenotype and genotype.
Before you begin to understand in more detail what a population is, you need to know and understand its main components. In total there are 5 main characteristics:
1. Distribution. It can be spatial and quantitative. The first type, in turn, is divided into a random and uniform distribution. The quantitative indicator is responsible for the size of the population or its separate group. The distribution of individuals depends on climatic conditions, the genome, the food chain and the degree of adaptation.
2. The number. This is a separate characteristic of the population, which should not be confused with the subspecies distribution. Here, the number is the total number of organisms in a particular unit of space. Most often it is dynamic. Depends on the ratio of mortality and fertility of individuals.
3. Density. Determined by biomass or the number of organisms per unit area (volume).4. Fertility. It is determined by the number of individuals that appeared as a result of reproduction per unit of time.
5. Mortality. It is divided by age criteria. Represents the number of life forms killed per unit of time.
At the moment there are the following types of populations: age, sex, genetic, environmental and spatial. Each of these variations has its specific structure. So, the age of the population is determined by the ratio of individuals of different generations. The same species can have both ancestors and piploda.
The genital population depends on the type of reproduction of the family and the totality of determined morphofunctional and anatomical characteristics of organisms. The genetic structure is determined by variations of alleles and the way they are exchanged. Ecological population is a division of the family into groups according to environmental factors. The spatial structure depends on the distribution and placement of individual individuals of the species in the area.
In different families this property depends on the environment and forms of coexistence. If the same species is moving in large spaces, such population can be called large. In the case of weak development of the ability distribution, the family is determined by small populations, which may reflect, for example, the mosaic of the landscape. Population of animals with a sedentary lifestyle and plants depends on the heterogeneity of the environment.The level of isolation of neighboring families of one species is different. In this case, populations can be sharply distributed in space or be clearly localized in a certain area. There is a continuous settlement of a huge area with one type. In turn, the boundaries between populations can be blurred and distinguishable.
The interaction and attitude of the species are carried out by means of individual contact. The most short-term is the predator's connection with the prey. The longest contact occurs when interacting with parasitic organisms.
Population: population dynamics
Today, the survival curve plays an important role in the study of species. It determines the degree of population size. This characteristic of the species depends on the survival ability of the family.The number dynamics can be of 3 types:
- most of the individuals live up to the maximum age threshold (humans and mammals),
- death can occur at any time (reptiles and birds),
- the mortality rate is high already in the early stages of development (fish, plants, invertebrates).
In some populations, this characteristic is caused by significant fluctuations. The main factors affecting the abundance of the species are food, environment, predators, parasites, climate, etc.
View as a unit of structure
The population consists of a set of individuals who are similar by morphological and physiological properties, habitat, the type of crossing, the origins. This group of organisms is called a species. Is the unit structure of the population. Species depend on the following criteria: morphological, genetic, physiological, biochemical. According to the additional classification, the characteristics of influence are geographic and ecological.
Each species arises, then develops and adapts. With a sharp change in the conditions of the environment, it can disappear.