Define population dynamics: I need a definition of population dynamics along with some of its characteristics?
please focus the population dynamics definition on ecological biology
POPULATION DYNAMICS DEFINITION:
- population dynamics deals with characteristics, structure and changes in population size and the factors causing the changes over time.
- population refers to a group of organisms of the same species i.e organisms of the same species i.e organisms are alike and can interbreed to produce fertile offspring…being that they have certain characteristics peculiar to them.
- demography deals with human population.
- population ecology is important for proper and guided use or utilization of available resources and environmental management.
Characteristics of populations.
- Number of individuals of population per unit area.
- example: number of neem tree in a hectare of land.
- crude density – all the area……… Ecological density…Actual area of occurence.
- Birth rate: rate at which individuals are being added to the population through reproductive processes at a particular time.
- birth rate is age-specific when only the offspring produced by the females of the reproductive age in a unit of time are considered. Note: females of reproductive age do not have the same capacity for giving birth to young ones.
- Gross Reproductive Rate – mean number of female births in each female age group.
- Net Reproductive Rate – fertility rate – number of birth per 1000 females of age 14 – 45 (reproductive age).
- Mortality: Death rate – number of death at a given period of time per unit population.
- Age Structure:
- the fate of a population depends on the ratio of the age groups in the population.
- the ratio is what determines the age structure of the population.
- the three age groups in a population are:
- pre-reproductive age
- post-reproductive age.
- Growth Rate: population growth rate is the average annual percent change in the population, resulting from increase or decrease of births over deaths and the balance between emigration and immigration, as a fraction of the initial population.
- population is said to increase when the sum of births (b) and immigration (i) exceeds deaths (d) and emigration (e). Thus: (b+i)>(d+e).
- the reproductive (biotic) potential of a population is the number of individuals in the population that have the capacity to produce maximum number of offspring possible.
- PGR = P(t2) – P(t1)/P(t1)
- the maximum rate of increase = (b+I) – (d+e)/t
- where there is abundance of food, space and other resources)
- sex ratio: this is the ratio of males to females in a population. the ratio is mostly 1:1 in most species. Gender imbalance may arise as consequence of various factors like
- natural factors
- exposure to harmful chemicals and other environmental contaminants.
- war casualties
- gender-selective abortions and infanticides