2.3 Measuring Biotic Components

What is classification?

Science of grouping organisms based on their physical characteristics.

What characteristics do we use?

Structures (morphology)Functions (physiology)BiochemistryGenetics

Why do we classify?

Identify organismsCompare organismsIdentify relationships among organismsCommunicate with others (universal

language)Identify evolutionary relationships

Why do we classify?What am I?FireflyLightning bugGlow FlyBlinkie Golden SparklerMoon bugGlühwürmchenLuciérnagaLucioleWe all have different names for the same

organism…this is a problem for communication.

From Aristotle to Linneaus

Aristotle (Greek philosopher) (384-322 B.C) First System of Classification

1. Plants Based on stem type

2. Animals Land, air or water

From Aristotle to Linneaus

Carolus Linneaus (Sweedish botanist) (1707-1778) Came up with modern classification system Used binomial nomenclature (2 word naming

system) This two word name is called a scientific name Composed of the genus name followed by the species

name

Scientific Names

Either written in italics or underlinedGenus is always capitalized and species is

always lowercaseBased on Latin Examples:

Cat: Felix domesticus Mosquito: Colex pipens Human: Homo sapien

Funny Scientific NamesAgra vation (a beetle)Colon rectum (another beetle)Ba humbugi (a snail)Aha ha ( a wasp)Lalapa lusa (a wasp)Leonardo davinci (a moth)Abra cadabra (a clam)Gelae baen, Gelae belae, Gelae donut, Gelae fish,

and Gelae rol (all types of fungus beetles)Villa manillae, Pieza kake and Reissa roni  (bee

flies)

Dichotomous Keys A series of yes/no questions about an organisms

structure Used to identify new and unknown organisms

Example of Dichotomous Key

1a. Hair Present…………..Class Mammalia1b. Hair Absent……………Go to statement 2

Example of Dichotomous Key

2a. Feathers present…………..Class Aves2b. Feathers absent…………….Go to statement 33a. Jaw Present…………………..Go to statement 43b. Jaw Absent……………………Class Agnatha

Example of Dichotomous Key

4a. Paired fins present……………Go to 54b. Paired fins absent…………….Go to 6

Example of Dichotomous Key

6a. Skin scales present………………Class Reptilia

6b. Skin scales absent……………….Class Ampibia

Estimating Populations of Organisms

We estimate populations because it would take way too long to count every living thing in a given ecosystem.

We can estimate populations of plants or animals

Random Sampling: All organisms must have an equal chance of being captured.

Estimating Populations of Animals

Lincoln index (capture-mark-release-recapture)n1 x n2N = n3

• N = Total number of population • n1 = Number of animals first (mark all of them)• n2= Number of animals captured in second sample• n3= Number of marked animals in second sample

Ex. 40 mice were caught, marked (tail tattoo) and released. Later, 10 mice were recaptured, 4 of which had tattoo marks.

Lincoln Index

Lincoln Index Assumptions

1. The marked animals are not affected (neither in behavior nor life expectancy).

2. The marked animals are completely mixed in the population.

3. The probability of capturing a marked animal is the same as that of capturing any member of the population.

4. Sampling time intervals must be small in relation to the total time of experiment of organisms life span.

5. The population is closed (no immigration and emigration)

6. No births or deaths in the period between sampling.

Estimating Populations of PlantsQuadrat Estimation

Population Density- The number of plants within the given area of the quadrat (m2)

Percentage Coverage- How much of the area of a quadrat is covered by plants?

Frequency- How often does a plant occur in each quadrat? Acacia senegalensis was present in 47 of 92

quadrats, for a frequency of 51%

Calculate Population Density

X X X W W

W X X W X

W X X X X

W X W X W

W z W W Y

What is the population density of species x ?

What is the population density of species Y?

What is the population density of species Z?

Quadrat 1= 0.5m2

Calculate Percentage Coverage

X X WW X X W X

W X X X

W X W

X W Y

What is the percentage of plant coverage in this quadrat?

Quadrat 1= 0.5m2

Percentage Frequency

X X X W WW X X W XW X X X XW X W X WW Z W W Y

What is the frequency of species X?

What about species V?

Z Z Z W WW Z Z Z ZW Z Z W ZW X W Z WW Z W W Y

Quadrat 2 Quadrat 3

X X X W WW X X W XW X X X XW X V X WW Z W W Y

Quadrat 1

Other Methods of Estimation(Plants)

Sampling – Take a sample from one area and assume the organisms are evenly spread out through the area. Biomass (dry weight) of living tissue

We use dry weight because water is non-living and needs to be excluded

Ex. 10 ferns were found in a 100m2 area. How many ferns would be in 1000m2 field in the same ecosystem?

What is diversity?

Diversity is the variety of lifeDiversity is a combination of two components

Evenness: The number individuals of each species present in a sample

Richness: The total number of different species in a sample

How Can We Know Diversity?

Use the Simpsons diversity index below

D = ____________N (N-1)_______________ n1(n1−1) + n2(n2 −1) + n3(n3 −1) +…nk(nk −1)

D = DiversityN = Total number of organisms of all speciesn = number of individuals of a particular species***The higher the D value the more diverse the sample is!!!!!

Example Data Calculations

  Abundance of Organism

  Ecosystem A Ecosystem B

species 1 3 5

species 2 7 4

species 3 26 12

species 4 9 7

species 5 7 0

Diversity 3.27