Ecology, ecogenetics

Ecology of populations
By population we call a set of individuals of the same species inhabiting a certain territory in a given time period.

Population ecology examines the influence of ecological factors on populations (demecology).

In a population, individuals are distributed in such a way that each has a probability of participating in the reproduction of the population's offspring. It is therefore a living system in which not only the biological properties of individuals are manifested, but also the biological properties of the entire group. A population can thus: grow, age, differentiate, maintain itself, have a certain structure, birth rate, mortality, dispersion, etc. Population ecology makes it possible to examine these characteristics, thereby contributing to a more complete knowledge Gene pool nature.

Dispersion
Dispersion (spreadsl) – distribution of individuals in the population, informs about the location of individuals in the inhabited area. Divided:


 * linear;
 * flat;
 * spatial.

Population density
Population density is subject to species-related changes:
 * Population density is related to the distribution of individuals - it is given by the number of individuals per unit area – abundance.


 * oscillations (fluctuations in frequency during 1 year);
 * fluctuations (fluctuations in abundance over several years, the result of mortality and birth rates).


 * Some species overgrow from time to time. Proliferation phase: gradation → gradation peak → culmination → retrogradation → latency → pregradation → progression with a new gradation peak.
 * Fluctuations in the number of populations are influenced by: climatic conditions, diseases, human interventions, ...
 * As a result of the uneven distribution of the vital components of the environment, animals are scattered in the landscape non-randomly and unevenly.
 * The social structure of the population and the gender ratio also play a role.

Age structure of the population

 * Another characteristic of the population is its age structure. From this point of view, we can divide the population into 3 categories:


 * 1) pre-productive;
 * 2) productive;
 * 3) postproductive (old individuals).

The animal population is subject to a kind of spatial activity, either during movement due to the expansion of the species, or also in search of warmth, reproduction, food, etc. Vertical activity (chamois) is interesting. A significant feature is the form of population growth:
 * Natality (multiplicity) is directly dependent on metabolic rate and inversely dependent on size.
 * Mortality (mortality rate).
 * 1) closed growth (S curve) – the maximum population density fluctuates around the so-called carrying capacity of the environment;
 * 2) open growth (J curve) – a gradual increase at first, then a sharp rise and finally a steep decline.

Ecogenetics

 * It studies hereditary differences in people's reactions to physical, biological and chemical environmental influences.
 * It follows on from pharmacokinetics and the development of modern medicine.

Physical influences

 * UV radiation – a strong mutagen for unicellular organisms. In humans, it is needed in small amounts for the production of vitamins. Protection is provided by the pigment.
 * Pigmentation is polygenically inherited, the level of protection is given genotype.
 * UV radiation causes Mutation, these are removed by reparation activities enzyme e. Persons with repair disorders have an increased risk of malignancies.
 * Diseases associated with sensitivity to UV radiation:


 * Xeroderma pigmentosum is an autosomal recessive disease. The skin is extremely sensitive to sunlight, cancers form at an early age in exposed areas. Endonuclease defect + mutation of about 6 others gen es, individuals with a combination Alleles Aa affected less.


 * Ataxia teleangiectasia.
 * Bloom syndrome (erythema congenitale teleangiectaticum Bloom) is an autosomal recessive syndrome of chromosomal instability.

Foodstuffs

 * Fats
 * Hyperlipemia with subsequent atherosclerosis, ICHS, Heart Attack.
 * Individual risk is determined not only by lifestyle, but also by genetic disposition.
 * The metabolism of fats depends on their transport in the blood, their binding to cell receptors and the breakdown of fats in cells.
 * The amount of fat can be influenced by diet and medication.
 * Salt
 * the sensitivity of sensors to salty taste is influenced by the threshold of sensitivity to salty taste and gender habits;
 * genetically conditioned, modified in childhood;
 * persons with a dominantly inherited disorder of transport of Na+ from cells and K+ into cells (Na-K pump);
 * arterial hypertension.
 * Milk
 * reduced lactase activity → undigested lactose → GIT problems;
 * AR hereditary lactase deficiency - atrophic enteritis;
 * degenerative changes in the renal canals
 * Flour
 * Persons with Celiac disease (gluten enteropathy) – it is the inability to break down gluten in flour, nutrient absorption disorders, digestive difficulties. Inheritance irregularly dominant. The condition can be modified by diet (gluten-free).
 * Proteins
 * Toxic for children with congenital disorders of amino acid metabolism (e.g. PKU, diet low in phenylalanine).
 * Alcohol
 * Alcoholism it is conditioned by social factors and genetically.
 * Alcohol dehydrogenases (ADH) – alcohol is metabolized in the liver to acetaldehyde (absorption already in the stomach).
 * Tolerance to alcohol is also affected by the activity of acetaldehyde dehydrogenase (ALDH).

Inhalants

 * dust (antitrypsin deficiency → pulmonary emphysema);
 * smoking (lung cancers);
 * Allergens (changes in the immune response, bronchial asthma).

Infection

 * 1) Insulin dependent DM (DM I.type):
 * 2) * manifestation in childhood;
 * 3) * the antigenic makeup (HLA haplotypes, DR3 and 4) is inherited – in 95% of those affected;
 * 4) Immune disorders:
 * 5) * Agama-globulinemia (GR);
 * 6) * aplasia thymus;
 * 7) * AIDS, mononucleosis due to the EB-virus;
 * 8) Ulcer disease of the stomach and duodenum:
 * 9) * Helicobacter pylori.
 * 10) Jaundice, TBC, …

related articles

 * Population polymorphisms
 * Multifactorial Inheritance
 * Origin and development of species
 * Evolution