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What Does Population Mean In Biology

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Effects Of Mode Of Reproduction: Sexual And Asexual

Biology Definition

In sexual populations, genes are recombined in each generation, and new genotypes may result. Offspring in most sexual species inherit half their genes from their mother and half from their father, and their genetic makeup is therefore different from either parent or any other individual in the population. In both sexually and asexually reproducing species, mutations are the single most important source of genetic variation. New favourable mutations that initially appear in separate individuals can be recombined in many ways over time within a sexual population.

In contrast, the offspring of an asexual individual are genetically identical to their parent. The only source of new gene combinations in asexual populations is mutation. Asexual populations accumulate genetic variation only at the rate at which their genes mutate. Favourable mutations arising in different asexual individuals have no way of recombining and eventually appearing together in any one individual, as they do in sexual populations.

Using Population Definition Biology

Causes of death are different in a variety of sections of Earth. Population is likewise an ecological unit which plays important part in ecosystem. They are more likely to be open.

Populations of distinct species dwell in communities. Ecosystems can be split into major biomes, which are characterized by a particular sort of geography, vegetation and climate. It is an effort to protect biodiversity.

Is Population A Statistics

In statistics, a population is the pool of individuals from which a statistical sample is drawn for a study. Thus, any selection of individuals grouped together by a common feature can be said to be a population. A sample is a statistically significant portion of a population, not an entire population.

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What Is Population Science Definition

A population is defined as a group of individuals of the same species living and interbreeding within a given area. Scientists study a population by examining how individuals in that population interact with each other and how the population as a whole interacts with its environment.

What is an example of a population in Science?

A population is a group of one particular species in a particular place. That group of birds that lives near your house, you know which one, is a good example.

What is population in basic Science?

A population is the number of organisms of the same species that live in a particular geographic area at the same time, with the capability of interbreeding. Population biology is the study of population characteristics and the factors that affect their size and distribution.

Evolution Of Genetic Systems

By assuming that there are loci that control the genetic system itself, population genetic models are created to describe the evolution of dominance and other forms of robustness, the evolution of sexual reproduction and recombination rates, the evolution of mutation rates, the evolution of evolutionary capacitors, the evolution of costly signalling traits, the evolution of ageing, and the evolution of co-operation. For example, most mutations are deleterious, so the optimal mutation rate for a species may be a trade-off between the damage from a high deleterious mutation rate and the metabolic costs of maintaining systems to reduce the mutation rate, such as DNA repair enzymes.

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Population Demographics And Dynamics

Chapter 19: Population and Community Ecology.

While population size and density describe a population at a particular time, scientists must use demography to review the dynamics of the population. Demography may be the record study of population changes with time: birth rates, dying rates, and existence expectancies. These population characteristics are frequently displayed inside a existence table.

  • Learning Objectives

Population Size Is Regulated By Factors That Are Dependent Or Independent Of Population Density

Biological and non-biological factors can influence population size. Biological factors include interspecific interactions like predation, competition, parasitism, and mutualism, as well as disease. Non-biological factors are environmental variables like temperature, precipitation, disturbance, pollution, salinity, and pH. All of these factors can change population size, but only the biological factors can regulate a population, meaning they push the population to an equilibrium density, or carrying capacity. Of the biological factors, mutualism does not regulate population size because mutualisms promote population increase through beneficial interactions with another species.

The biological factors of competition, predation, etc. that regulate population growth affect dense versus sparse populations differently. For instance, communicable disease doesnt spread quickly in a sparsely packed population, but in a dense population, like humans living in a college residence hall, disease can spread quickly through contact between individuals. Density plays a key role in population regulation in the following ways:

  • Territoriality: Maintaining a territory will enable an individual to capture enough food to reproduce, where space is a limiting resource.
  • Disease: Transmission rate often depends on population density
  • Predation: Predators may concentrate on the most abundant prey
  • Toxic Wastes: Metabolic by-products accumulate as populations grow

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The Origins Of Population Genetics

To understand how population genetics came into being, and toappreciate its intellectual significance, a brief excursion into thehistory of biology is necessary. Darwin’s Origin of Species,published in 1859, propounded two main theses: firstly, that modernspecies were descended from common ancestors, and secondly that theprocess of natural selection was the major mechanism of evolutionarychange. The first thesis quickly won acceptance in the scientificcommunity, but the second did not. Many people found it difficult toaccept that natural selection could play the explanatory role requiredof it by Darwin’s theory. This situationaccepting thatevolution had happened but doubting Darwin’s account of what hadcaused it to happenpersisted well into the twentiethcentury .

Opposition to natural selection was understandable, for Darwin’stheory, though compelling, contained a major lacuna: an account of themechanism of inheritance. For evolution by natural selection to occur,it is necessary that parents should tend to resemble their offspring otherwise, fitness-enhancing traits will have no tendency to spreadthrough a population. In theOrigin, Darwin rested his argument on the observed fact thatoffspring do tend to resemble their parentsthestrong principle of inheritancewhile admitting that hedid not know why this was. Darwin did later attempt an explicit theoryof inheritance, based on hypothetical entities calledgemmules, but it turned out to have no basis in fact.

This Article Is A Part Of The Guide:

What is Biology? The Characteristics of Life.
  • 3.12Poisonous and Venomous Animals
  • Although there are individual behaviors that can be studied populations also have characteristics that relate to them as a cohesive unit. They have a growth rate which is related to the birth and death rates of the population. They also have an age structure and genetic fitness.

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    Population Size Density And Distribution

    Communities are made up of populations of different species. In biology, a population is a group of organisms of the same species that live in the same area. The population is the unit of natural selection and evolution. How large a population is and how fast it is growing are often used as measures of its health.

    Adaptations Interdependence And Competition

    Organisms depend on each other for survival. This is called interdependence. Both living and non-living factors will affect the abundance and distribution of organisms in a habitat.

    • is the interaction between a community of living organisms and their environment
    • the environment consists of all the conditions that surround any living organism – both the other living things and the non-living things or physical surroundings
    • is all the organisms of the same or closely-related species in an area

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    What Do You Mean By Population Ecology

    Population ecology is the study of these and other questions about what factors affect population and how and why a population changes over time. Population ecology has its deepest historic roots, and its richest development, in the study of population growth, regulation, and dynamics, or demography.

    What Is So Fascinating About Population Definition Biology

    1 obvious advantage a variety of folks believe are offered in a large population is an elevated amount of human resources. Migration desires a great deal of energy and several individuals die during migration. You should begin paying up nearly all your center towards last, found, and potential elements of your charm report.

    Governments increasingly supply the wellness services that enable couples to plan their families. Living our lives targeting average for decades isnt likely to provide access to somebodys full wellness potential. By means of example, social media groups allow various individuals to communicate with one another through a dynamic web of relationships.

    Patterns of population abundance are affected by means of a selection of biological and physical things. Population bottleneck is a decrease in the size of population for a brief time. A population is made up of a group of people who dwell in a particular habitat at a particular moment.

    In each instance, humans have provided the environmental challenge in the kind of poisons acting on the populace. Additionally, the boundaries of the ring species are hard to distinguish. The majority of the biospheres life is found between 500 meters under the face of the ocean and six kilometers over the surface of the planet, though there are organisms, especially microorganisms, able to reside at much higher and lower depths.

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    The Fight Against Population Definition Biology

    The idea of synbio foods is a remarkable deal less selfish that the idea of GMOs. Lets examine some of the general factors theyd consider. The patients response to a trigger is composed of complex, web-like influences on the biologic system called mediators.

    Every different section might have a subject sentence thats one of the very best reasons to believe that the thesis. This definition works nicely with animals. Differences between species may be the result of natural selection.

    When and in the event you choose to come out to them, it might be helpful to prepare what youd like to say beforehand. term paper writer The problem is that extended fasting isnt a fantastic long-term fat loss strategy. The consequent dialogue box is just the exact same as for phrase 2007.

    A simple phase diagram proves that the custom of sublimation isnt as complicated. Synthetic biology is merely designing genomes. These definitions are just wrong.

    The Population Definition Biology Stories

    For a consequence, in diploma it involves a considerable quantity of qualities, but its really not a product that might be worthwhile in the possess specific daily life. When you inform us about all the paper info, we will begin attempting to come across a perfect writer for your paper. Without the ability to change, organisms using that material wouldnt have the capability to evolve.

    The notion of a community, is dependent on the manner that its defined. Whenever you have settled on a really superior term paper for sale research topic, the subsequent thing you would like to form is a strong thesis statement. Theres a huge number of suggestions that may have to be adhered to when preparing the assignments to earn sure decent quality isnt compromised.

    The choice of individuals a particular habitat or environment can support is called the carrying capacity. Even the price of faculty essays on the web is cheap for fiscal convenience of the customers. The next degree of organization is an ecosystem, which contains all living things in a specific area, plus all the non-living elements of the surroundings.

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    Philosophical Issues In Population Genetics

    Population genetics raises a number of interesting philosophicalissues. One such issue concerns the concept of the gene itself. As wehave seen, population genetics came into being in the 1920s and 1930s,long before the molecular structure of genes had been discovered. Inthese pre-molecular days, the gene was a theoretical entity,postulated in order to explain observed patterns of inheritance inbreeding experiments what genes were made of, how they causedphenotypic changes, and how they were transmitted from parent tooffspring were not known. Today we do know the answers to thesequestions, thanks to the spectacular success of the molecular geneticsushered in by Watson and Crick’s discovery of the structure of DNA in1953. The gene has gone from being a theoretical entity to beingsomething that can actually be manipulated in the laboratory.

    To conclude, it is unsurprising to find so much philosophicaldiscussion of population genetics given its centrality to evolutionarybiology, a science which has long attracted the attention ofphilosophers. The preceding discussion has focused on the mostprominent debates surrounding population genetics in the recentphilosophical literature but in fact population genetics is relevant,at least indirectly, to virtually all of the topics traditionallydiscussed by philosophers of evolutionary biology.

    How Population Size And Density Are Calculated

    Exponential and logistic growth in populations | Ecology | Khan Academy

    Quadrat method: Ideally, population size could be determined by counting every individual in a habitat. This is highly impractical in many cases, if not impossible, so ecologists often have to extrapolate such information.

    In the case of very small organisms, slow movers, plants or other non-mobile organisms, scientists scan use what is called a quadrat . A quadrat entails marking off same-sized squares inside a habitat. Often string and wood are used. Then, researchers can more easily count the individuals within the quadrat.

    Different quadrats can be placed in different areas so that researchers get random samples. The data collected from counting the individuals in the quadrats is then used to extrapolate population size.

    Obviously a quadrat would not work for animals that move a round a great deal. So to determine the population size of more mobile organisms, scientists use a method called .

    In this scenario, individual animals are captured and then marked with a tag, band, paint or something similar. The animal is released back into its environment. Then at a later date, another set of animals is captured, and that set may include those already marked, as well as unmarked animals.

    The result of capturing both marked and unmarked animals gives researchers a ratio to use, and from that, they can calculate estimated population size.

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    Propositions 1 And : Critically Parsing Population Rates And Theircomparisons

    Consider, first, three illustrative cases pertaining to analyses of populationrates of breast cancer:

  • A recent high-profile analysis of the global burden of breast cancer, whichestimated and compared rates across countries, accompanied byinterpretative text, with the article stating, for example, thatColombia and Venezuela have very different trends,despite sharing many of the same lifestyle and demographicfactors, followed by the inference that the explanationof these divergent trends may lie in the interaction between genes andindividual risk factors.
  • Typical reviews of the global epidemiology of breast cancer, whichcontain such statements as Population-based statistics show thatglobally, when compared to whites, women of African ancestry tendto have more aggressive breast cancers that present more frequently asestrogen receptor negative tumors and early onset ERnegative tumors also develop more frequently in Asian Indian andPakistani women and in women from other parts of Asia, although not asprevalent as it is in West Africa.
  • The headline-making news that the U.S. breast cancer incidence rate in2003 unexpectedly dropped by 10 percent, a huge decrease .
  • Population: Definition Attributes And Growth


    In this article we will discuss about:- 1. Definition of Population 2. Population Attributes 3. Growth.

    Definition of Population:

    Population is a set of individuals of a particular species, which are found in a particular geographical area.

    The population that occupies a very small area, is smaller in size, such a population is called local population. A group of such a closely related local population is called meta-population.


    Population ecology is an important area of ecology because it links ecology to the population genetics and evolution. Natural selection operates at a levels of population.

    Population Attributes:

    A population has certain attributes that an individual organism does not have.

    Some of them are given below:

    Population Size or Density:


    It is the number of individuals of a species per unit area or volume

    Birth Rate :

    It is the rate of production of new individuals per unit of population per unit time. For example, if in a pond, there are 20 lotus plants last year and through reproduction, 8 new plants are added, taking the current population to 28. Then, birth rate = 8/20 = 0.4 offspring per lotus per year.

    Death Rate :

    Sex Ratio:

    An individual is either a male or a female but a population has a sex ratio like 60% of the population are females and 40% are males.

    Age Pyramid:


    The age pyramids of human population generally shows the age distribution of males and females in a combined diagram.

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    Selection At One Locus

    Natural selection occurs when some genotypic variants in a populationenjoy a survival or reproduction advantage over others. The simplestpopulation-genetic model of natural selection assumes one autosomallocus with two alleles, A1 andA2, as above. The three diploid genotypesA1A1,A1A2 andA2A2 have different fitnesses,denoted by w11, w12 andw22 respectively. These fitnesses are assumed tobe constant across generations. A genotype’s fitness may be defined,in this context, as the average number of successful gametes that anorganism of that genotype contributes to the nextgenerationwhich depends on how well the organism survives, howmany matings it achieves, and how fertile it is. Unlessw11, w12 andw22 are all equal, then natural selection willoccur, possibly leading the genetic composition of the population tochange.

    Suppose that initially, i.e. before selection has operated, the zygotegenotypes are in Hardy-Weinberg proportions and the frequencies of theA1 and A2 alleles arep and q respectively, where p + q= 1. The zygotes then grow to adulthood and reproduce, giving rise toa new generation of offspring zygotes. Our task is to compute thefrequencies of A1 and A2 inthe second generation let us denote these by p andq respectively, where p +q = 1.

    pq /w

    Equations and show, in precise terms, how fitness differencesbetween genotypes will lead to evolutionary change. This enables us toexplore the consequences of various different selectiveregimes.

    p +q = 0

    which reduces to

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