Unit 2: Population Study

UNIT-2 POPULATION STUDY 1. Unique & group attributes of population (a) population density (b) Survivort ship cureve 6) Natality (9) sex ratio (C) Montality Age ratio (d) Life table (1) Dispersal and Fecundity table (J) dispension 2. Equation and Patterns (M) Exponetial & logistic growth (a) re & K-studies 3. population régulation (a) Density dependent factoris (6) Density independent factorys! 4. Population interaction. e) Gause's principle with labarjotary example and Field example. Q.1 Attributes of Population →A Population has characterstics that it shares with an organism as well as the chanactenstice that one tit own. → the bonmen indivisual may be called "biobgical attributes". → The next term that is unique attributes ane langely Statistical this is not to cay that a population is unique only al a stactical entity 7 Rather it is also say that biological teatures express themselves as statistical tunction which emenge at the group level as new biological expressions. → at least 5 general attributes are exhibited by population and organisms there are In A debinite structure and composition is constant for any moment of time but bluctuate with age. (2) The population exhibit growth, ditterentiation, division eb Labour, maintenance, senescence (aging process of body) and death Population has henedity (4) The population is integrated by both genetic and Integrated bactons (5) The population should meet the impact of environment. → A population is a group of living individuals which are bonmed in a particular time and space the essential and litteriential group of biology is that it consider group as wholes. It aims to describe the attributes and behaviour of a group as such →The concept of group attribute, separate and dibberent brom the attributel is a bamiliar one in other bield. → the bamily are measurel a variations such as standard deviation are the quantitative expression of a grap attni bates. 1. Population De Density →size/dencity of a population is its basic characteristics, → population density may be debined as population size in relation to some unit of space. →Density is one of the mearuning criteria mattern bore population size is devided by total land area. → these are some bactors that affecte population density populationsize is devided by total land area.. →There are come bactors that affects population density.. which are (1) Natality (2) Montality (3) Food supply on some ethen influente. Source of + population density may change withnfea food supply → there is alimit of population denicity with respect to the trophic level. population density gives as the information about magnitude of population but is also gives information about the distribution path. (impune) cruden density, the density /runtor →Population density may be crudendens /biomass, per unit arrea/space. → Ecological density is, the number/biomass unit of habitat/space That is available, at volume that can be actually colonised by population. 15 Population index ~ ~ (1/10) Due to out Binancial/time constainty it may not be possible to cariny a total count of a particular population It's alko, impontant to know the increasing/decreasing as a result of which densit be calculated which density may be calculated density may alterr In a particular, anea population density may after with respect to time.. دا → Hence these methods may not the animals but to get the sign. give direct seeing hearing +It means tixed amount of searching effort will locate a bixed location of the population. 2. Natality 01911 Matality of population is also called birth nate It is cimply a broaded Forim covering the production of new individuals of any organisms of a population. →Natality is the population increasing Factory It may also be debined as bonce of total population reproduction New individuals are hatched germinated anised by division. Strictly in human population birth rate is term which may be used in place of natality →Two types of natality are generall show seen (1) maximum) of absolute natality (2) Ecological / realised natality. → maximum natality is the theoritical maximum production of new individuals undern ideal condition 7 Ecological natality nebens to a population in which Population actually existing underr a specific condition. → Matality is generally expressed as anate dettenmined by dividing the number of new individuals produced per unit population. by time one problem in comparing the natality of dibterrent species population is the difficulty of measure in natality at comparable Stages in the lite history. 1 7 Specific natality can be detined as specific nabality Makes pen dibtenent age groups in the population 7 Maximum Natality on the otherthand is the theoritical upper limit which the population would be capable of Producing under the ideal condition: Nomino 3. Mortality •Mortality nerens to death of individuals in a population Moritality rate is equivalent to death rate in human, demogranty catagories are recognized (1) Ecological 12 ca 2 Specific mortality *Ecological Montality It is also called realised moritality it is loss of individuals unden a given environmental condition. It is not constant, but vanies with population and environmental condition. Specific Montality yst is also called potential mortality this is the theoritical minimum. montality. A constant for a populations which represents the lower under ideal/ limiting condition that is even under the best Conditions individual would die of old age non- → Generally old age determined by physiological: longivity In other terim specific moritality is expressed as a pericentage of initial population dying within a given time. → often it is the sunvival Mate ie of greater, in tenest than the death rate. → As with natality both minimum mortality reate and the actual montality rate are of interrest → It is the m measuring stick torp comparision Because of even, undef ideal condition individuals of any population die of old age there is a minimum mortality that would ocean under best porcible conditions this should be determined by average physiological Lengetivity of the individuals. → However, in some population mortality rate may dibtery undere minimum natural conditione. Hence, neithery population size not the trend can be determined by montality (4) Life tables → Since mortality varties greatly with age, as does natality specific mortality at as many dibrenent ager as possible ane of great interest in as much as they enable us to determine the tonces under lying the crude, overall population mortality. 7 A complete picture of moritality survivorship with in population is given a table called lite table. in of individuals a systematic way through → Lite table is reliable method bort keeping recorid of births, deaths & reproductive cutput of a population interrest. 7 Ecologist learined this approach brom lite insurance industry. Basically thene are 2 types of lite tables Horizontal life table. (2) Static (vertical lite table) Honizontal lite table ohard 7It is also called forenda lite table + greup et enganism borin at the same time is called "Lohand → The lite table ie. prepared with such data ane called cohard" Cchand/horizontal lite table 7It is a stredy that includes a group of population /plants Seeding that germinated at same time 7 constructing La cohand lite table a group at same aged individuals are required. 7 they can be used to determine age, specific mortality! Mate, basic reproductive rates, so that annual variation Can be analysed. Figune (2) Static Live table (Vertical Life table) The second way to estimate patterne of survival pr a population is to recond the age at death of the lange number of individuak. → This method dibbens brom cohond like table because the Individuals in thit sample are borin at dibterrent times! The stable is called static because the method Involves a Sharep Seampie net survival with in a population during interval at time. a chont → Ideally, in static like table population is neither increasing nor decreasing. Static life table makes two important assumptions (a14 population has a stable age structure 1b) The population size is nearlly stationary" → To produce Static life table the the age at which they die. the biologists" "need to estimate This can be done by tagging individuals when they then recovering the stage after death. Figure they are born f 420 Utility of like table Life table helps to comparie 'Survivorship path It can 'Find age specific montality. It can also, Find libe expectency It can calculate population growth rate. 5) Survivor chip curves 7 Fon a population the important thing is not tow many individuals die but which member sunviveε. → The survival rates are much interest than the deaths pater when a greaph is plotted taking 2 bacrons in to consideration ie total numbers of individuals and libe span, the cartve that is resulted is a cunvivonship curves. Ecologist propoted 3 majory catagonies of survivorship curves (1) Highly conven cunves 2) Highly concave curves (3) Diagonal curvel (1) Highly convex curves A highly corven curve is charracterstic of species in which Population mortality rate is low until neary the end of the libespan. (2) Highly concave. Curves www This is other example of survivorship curves when montality. is high during young stages such type of curve is available. (3) Diagonal cunve These are the Patterins in which the age specibic survival is mone nearly constant so that the curve approach a straight line. (6) Age Natio → The relative abundance of various age in a population is called the age natio. → It is also called Age distribution of population. 7 It is an important ecological bactory yage distribution extects both natality and montality rates. → It is related with sunvival reproductive of potential tor buture growth. →Age distribution Indicates periods of successful reproфиснал reniods of high & low survival weather the alden individuals in a population are is declining. replacing the meselves or the population By studying the history of a population population ecologiste can make prediction about the Fortune. usually , the ratio of vanioul ages. determines the neproductive status. in a population alco → Rapidly growing population contains lange numbers of young individuale. de Clining individuak. population contains Larige rumbers, ob old Raw & Functional Age, →Raw age simply means the age of an organisms, days months. in terms of → It is the simplest measure born age Aut ditticulter anise, when compartisions are made. Functional age in the other hand is called "Ecological Age". A population is said to have individuals belong in to this catagony with bollowing (3) post-reproductive (1)pre-reproductive (2 Reproductive Stable age distribution A population having a monelless constant proportion of individual of dittenent is said to have a stable age distribution. Age pyramid An age pyramid is a vertical bary graph in which the numbert et individuals in various range at any given time is shown triom the youngere at the bottom and the oldere at the top. (7) Sex Maio sex natio is the ratio of male to bemale in a population. 7 → Great variations exist among "animals interims of the numbery of male and female individuals. egy Honey beer a single queen honey bee is responsible 807 production of queen workers of the drone. Age and sex ratio are important influence on the birth Mate It the rate is not maintained population dynamic get ebtected. sex ratio is usually expressed as malesi bemales to make to make total hundred (50:50) 7 In case of Range mammals it is costumary to maintain the percentage generally. + the verbal expression of the sex ratio says that it is male/temale biased. → In most species sex ratio varies according to the age Probile in a population. It may be (1) Primary sex ratio: The point at which the sperm bertilizes the orum. (2) Secondary sey natio: at the time of hatching /Biri (3) Tentiary sex ratio: sequally active / maturated organisms. (4) Quaternary sex mano: Itd's the post reproductive stage. Factors Abrecting sex ratio: Various tactons are known to attect the sex ratio like (1) Density independent montality 2) Interspecific competition (3) Breeding pattern (4) (nowding 8) Dispersal and dispension Dispension: → The dispension et population is the description of pattern of distribution of organism in space in change in dispension pattern are generally considered along with changes in size, while interpreting population dynamics. 7 Indivi quak in a population may be distributed according to the three basic patterns. Randomy this type of distribution is veny name, where the environment unitonm Bi uniformy It is, mone regulan type e) Clumpedy In clumped distribution the individual like close together like groups Dispensal (alla) pepectation dispensal is the movement of individuals / propagules into/out to the population. → Dispensal is the means by which new aneas are colonised and equilibrium diversity is established.. → all animals donot spread across the barniens with the same speed come ane tastery, some are slow and some do not cross at all. There are dibt erent types of barriers boy dispensal like Land bridges 12) wind and stomme Dss through blade birds Human agencies 5) sweeps takes Ebrect of dispersal en population → Dispersal supplements natality & montality shaping population growth brom & density.. 7 The ettect that dispersal will have on a population depende Finct con the status of the growth brom of the population of 2nd on the rate of dispersal. In most caser some individuals) theiry neproductive products are constantly entering / Reaving population. But regulan/ Graqual type of dispensal queinot ettet mone on a population.