# Population

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## Presentation Transcript

### Population :

Population - A group of species occupying a particular space at a particular time Characteristics: Size or Density Age distribution Genetic composition Pattern distribution

### NATALITY& MORTALITY :

NATALITY& MORTALITY Life Tables - is termed demography which tells how the populations grow Time-Specific Life Tables Age- Specific Life Tables Reproductive Rate-Fecundity Deterministic model: Geometric Growth Stochastic Growth

### Population Parameters that affect the size /density :

Population Parameters that affect the size /density DENSITY EMIGRATION - IMMIGRATION MORTALITY NATALITY + - +

### Density :

Density numbers of species/unit area or per unit volume FORMULA: Density = No. of species Total area

### Slide 5:

TYPES OF DENSITY 1. Absolute Density Total Counts – human population, large plants on small areas and territorial birds

### Sampling Methods - counting a small proportions and use the sample to estimate the total.. :

Sampling Methods - counting a small proportions and use the sample to estimate the total.. Use of Quadrats – count all the species on several quadrants of known size and get the average of the whole area used extensively in sampling plants TYPE OF DENSITY

### Sampling Methods :

Sampling Methods Capture-Recapture Method – capture, marking, release and recapture is extensively used in animal ecology, can also be use to estimate" birth-rate “ and “death rate”

### B. Measurements of Relative Density - is expressed as a percentage of the total density :

B. Measurements of Relative Density - is expressed as a percentage of the total density FORMULA: Relative Density of a Species = Density of species Total densities of all species X 100

### Measurements of Relative Density :

Traps – number of species are determined and their activities Number of Fecal pellets – the average rate of defacation can get the index of population size Measurements of Relative Density

### Slide 10:

Measurements of Relative Density Vocalization frequency- humming of birds,pheasant calls are used as index of population size Pelt Records – number of animals caught that extend back a century Catch per unit fishing effort –index of fish abundance per 100 hours of trawling

### Measurements of Relative Density :

Measurements of Relative Density Number of artifacts- counts for organism that leave evidence of their activities Questionnaire – this can be sent to different scientists/trappers to get a subjective estimate of population Frequency – calculating the sum of quadrats in which a particular species occurs Formula: F = number of species/number of the total quadrats Feeding Capacity –the amount of bait taken by the species in a given time

### SAMPLING PLANT POPULATIONS :

SAMPLING PLANT POPULATIONS Quadrats/Sample Plots List Quadrat-organisms found are listed by name only Count Quadrat – numbers and names are recorded Chart Quadrat – mapped to show the location of different species Cover Quadrat - to know what percentage of the land surface in the study area is “covered’ by a certain species.

### Slide 13:

Belt Transect- cross section of an area used as sample for mapping, recording or studying vegetation Line Intercept-one dimensional, used for shrubs stands, woody plants in the forests SAMPLING PLANT POPULATIONS

### Slide 14:

Point Quarter Method- using the radius method of forest sampling Dendrochronolgy- aging of trees by using growth rings SAMPLING PLANT POPULATIONS

### Slide 15:

Phytoplankton - can be obtained drawing water sample from several depths -Sedgewich-Rafter counting chamber or Whipple ocular or by filtration Periphyton - by using the transmission of light to pass through a thin or transparent leaves ALGAE

### Sampling Animal Populations :

Sampling Animal Populations Flying Insects Diurnal insects- using aerial nets - Nocturnal insects – by using traps containing UV light or mercury vapor light or if the insects are to be killed we can use plaster of Paris

### Slide 17:

Aquatic Organisms - dip nets -bottom nets - wire basket scraper nets - plankton towing nets - aquatic throw nets Birds and Mammals - live traps with baits - marking with cellulose paint for arthropods - ship-fouling paint for mollusks and insects - strap tags for fishes - toe clipping for frogs toads and salamander Sampling Animal Populations

### SOIL ORGANISMS :

SOIL ORGANISMS can be extracted from the soil by using Tullgren funnel Flotation Funnels for spiders and beetles Sticky boards for millipeedes,slugs,and centipedes Meat bait in small wire - Combination of formalin and shovel for sampling earthworm