Explain the specific attributes of a population.

(N/A) In nature,we rarely find individuals of any species living in isolation; most of them live in groups in a well-defined geographical area,share or compete for similar resources,potentially interbreed,and thus form a population.
Although the term interbreeding implies sexual reproduction,a group of individuals resulting from even asexual reproduction is also generally considered a population for the purpose of ecological studies. Examples include all cormorants in a wetland,rats in an abandoned dwelling,teakwood trees in a forest tract,bacteria in a culture plate,and lotus plants in a pond.
While an individual organism is the one that has to cope with a changed environment,it is at the population level that natural selection operates to evolve the desired traits. Population ecology is,therefore,an important area of ecology because it links ecology to population genetics and evolution.
$A$ population has certain attributes that an individual organism does not. An individual may have births and deaths,but a population has birth rates and death rates. In a population,these rates refer to per capita births and deaths. The rates,hence,expressed are change in numbers with respect to the members of the population.
For example,if in a pond there were $20$ lotus plants last year and through reproduction $8$ new plants are added,taking the current population to $28$,we calculate the birth rate as $8/20 = 0.4$ offspring per lotus per year. If $4$ individuals in a laboratory population of $40$ fruit flies died during a specified time interval,say a week,the death rate in the population during that period is $4/40 = 0.1$ individuals per fruit fly per week.
Another attribute characteristic of a population is sex ratio. An individual is either a male or a female,but a population has a sex ratio (e.g.,$60 \%$ of the population are females and $40 \%$ are males).
$A$ population at any given time is composed of individuals of different ages.