Biology
Ecology
It is the scientific study of ecosystems
Can you define the following words?
Species Habitat Population Community Ecosystem : it is a biological community of interacting organisms and their physical environment. Biosphere is the global sum of all ecosystems.
Ecosystem
Is made up of two components
A. Biotic factors: all the living livin g organisms Abiotic factors: The physical physica l or non-living part of the ecosystem. Examples of abiotic factors includes: •
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Water Sunlight Soil: structure Humidity/moisture Atmospheric gases Pressure and sound (for marine habitats) Can you add to this list?
Abiotic factorfactor- Light
Photosynthesis Light intensity affects photosynthesis rate Plants living on forest floor prefer shade, other prefer greater light intensity
Abiotic factors-light factors-light
Length of day/night affects flowering and fruiting of plants in seasonal regions of Earth
Abiotic Factors-soil Factors-soil
Importance of Soil Anchorage Provision of nutrients/minerals nutrients/minerals Provision of water Air to plants and soil organisms organisms
Soil Formation-Weathering Formation-Weathering of rocks
There are three main methods
Physical: e.g. action of water waves Chemical: e.g. acid rain Biological : action of microorganisms or plant roots
Components of soil
Four components of soil Mineral matter Organic matter Water content Air content
How will the above affect plants and animal lives?
Types of Soil
Lots of clay, little sand and
1/2 sand, 1/3 clay and 1/6
Lots of sand, little clay and
little humus
load
humus
Many sm small cla clay y pa particle icless
Mixture of of lar larg ge an and sm small all
Many large particles of sand
particles Water drains poorly (high
Water drains well
retentivity)
Water drains too easily (low retentivity) so soil is dry
Small air spaces, little air
Intermediate size air space
Large air space
Heavy to dig
Intermediate
Light and easy to dig
Can be waterlogged easily
Intermediate
Minerals are leached out of soil more quickly
High water holding capacity
Intermediate
Low water holding capacity
Biotic Factors
Symbio Sym biosis sis-- Rev Revisi ision on
Symbiosis: is a close and often long-term interaction between two or more different different biological species Three main types:
Mutualism Commensalism Parasitism
Mutualism Mutualism is the way two organisms of different species exist in a relationship in which each individual benefits. Explain how the organisms benefit from each other
Mutualism
Mutualism: Clown fish and Sea anemones
Sea anemones capture their prey by paralyzing them with discharged cnidoblasts. But Clownfish are not affected Suggest what the sea anemone gains from this relationship
Image source: http://facstaff.cbu http://facstaff.cbu.edu/~sei .edu/~seisen/Exampl sen/ExamplesOfMutua esOfMutualism.htm lism.htm
Mutualism in leguminous Plants
Commensalism
In ecology, commensalism is a class of relationship between two organisms where where one organism benefits without affecting the other.
Commensalism: leopard shark and remora
Parasitism
Parasitism is a non-mutual symbiotic relationship between species, where one species, the parasite, benefits at the expense of the other, the host.
Ecological Study Techniques A sample study is done , i.e. a small portion of an area is studied Why? It is impossible to count all the number of plants of animals in an area
Precausion Avoid degrading the habitat/environment Avoid removing organism from their natural habitat
Ecological Study Techniques
1. Quadrats
It is a square metal or wood frame of known area
It is used to estimate the number of species in an ecosystem
E.g. to estimate # of weeds in an area A sample area area is studied, then, the information is used to estimate estimate the number of species in the entire area
E.g. 1m2 Quadrats are thrown 10 times at random in a 300 m 2 area. The average per throw is calculated. That number is then multiplied by 300 to estimate the total number in the area
Example showing how the number of weeds in an area can be estimated
Quadrat
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(Throws)
Organisms
Total # =90 Average per throw = 90/10 =9 (density) 2 = 9 * 300 Estimated number in 300 m =2700 species
Quadrats
Quadrat frames, constructed from wood from wood or metal,, are used to investigate the distribution metal of species
Square quadrat frame for determining population densities
Subdivided quadrat frame for determining % cover of species
Ecological study using Quadrat
Ecological Study Technique
2. Nets
Nets are used for sampling small moving animals such as insects. They can also be used to estimate the number of species in pond.
http://wiki.bugwood.org/upload http://wiki.bug wood.org/uploads/Fig27_b s/Fig27_bugnet.jpg ugnet.jpg
Nets
Using sweep nets for ecological studies
Ecological Study Technique
3. Transects
Line transects are used in habitats where there is a clear change in conditions and the distribution of the vegetation or sessile (immobile) animal from one point to another. E.g. of area that can be studied : river banks and swampy areas
A line transect transect is one in which all all individual organisms organisms touching touching the tape/string are recorded
Ecological Study Technique
Jars/bottles and pitfall traps
Bottles can be used to set pitfall traps, so that they cannot escape easily Jars/bottles can be used to study aquatic organisms, e.g. a person may collect a few sample of water from a stream, river, trench, trench, then take the sample to a lab, and then identify microorganism microorganism using a microscope, or by culture technique (using agar plates)
Line Transect
http://teacheratsea.wor http://teach eratsea.wordpress.com/ dpress.com/2013/07/3 2013/07/31/julia-harvey-de 1/julia-harvey-determining-populat termining-population-sizeaion-sizea-
Pitfall trap
http://www.bbc.co.uk/bitesize/s http://www.bbc.co.uk /bitesize/standard/b tandard/biology/biosphe iology/biosphere/investiga re/investigating_an_ecos ting_an_ecosystem/revisi ystem/revision/3 on/3 /
Transects
Belt transect involves laying a tape through the area of study and sampling the population with Quadrats positioned at regular intervals alongside the tape
Species Frequency
The percentage frequency of a species is the percentage of sample units (usually Quadrats) in which the species species occurs. E.g. If a species X occurs in 10 out of 25 Quadrats thrown randomly, what is its frequency? Solution:
= 10/25 * 100 = 40 %
Density
Density of a population is the number of organisms in 1m2 found using a quadrat of sides 1m. Average number of organisms inside the quadrat on ten throws is the density. Check slide 22
ANY QUESTIONS?
Lab # 20 Aim: Introduction
