bioknowledgy presentation on 4.1 species, communities and ecosystems

Essential idea: The continued survival of living organisms including humans depends on sustainable communities.

By Chris Paine

https://bioknowledgy.weebly.com/

Honey bees are in decline in many parts of the world, the phenomena is known as Colony Collapse Disorder (CCD). Though many factors, including parasites are involved it is likely that a major factor is in CCD is modern farming practices, particularly pesticide use. This is ironic given that approximately a third of all crops rely on bees for pollination. Food production is reliant on healthy, sustainable communities of animals surrounding the agricultural land.

4.1 Species, communities and ecosystems

http://www.gaiahealthblog.com/wordpress1/wp-content/uploads/2013/11/bee-and-daisy.jpg








Understandings

Statement Guidance4.1.U1 Species are groups of organisms that can potentially

interbreed to produce fertile offspring.

4.1.U2 Members of a species may be reproductively isolated in separate populations.

4.1.U3 Species have either an autotrophic or heterotrophic method of nutrition (a few species have both methods).

4.1.U4 Consumers are heterotrophs that feed on living organisms by ingestion.

4.1.U5 Detritivores are heterotrophs that obtain organic nutrients from detritus by internal digestion.

4.1.U6 Saprotrophs are heterotrophs that obtain organic nutrients from dead organisms by external digestion.

4.1.U7 A community is formed by populations of different species living together and interacting with each other.

4.1.U8 A community forms an ecosystem by its interactions with the abiotic environment.

4.1.U9 Autotrophs obtain inorganic nutrients from the abiotic environment.

4.1.U10 The supply of inorganic nutrients is maintained by nutrient cycling.

4.1.U11 Ecosystems have the potential to be sustainable over long periods of time.

Applications and Skills

Statement Guidance4.1.S1 Classifying species as autotrophs, consumers,

detritivores or saprotrophs from a knowledge of their mode of nutrition.

4.1.S2 Setting up sealed mesocosms to try to establish sustainability. (Practical 5)

Mesocosms can be set up in open tanks, but sealed glass vessels are preferable because entry and exit of matter can be prevented but light can enter and heat can leave. Aquatic systems are likely to be more successful than terrestrial ones.

4.1.S3 Testing for association between two species using the chi-squared test with data obtained by quadrat sampling.

To obtain data for the chi-squared test, an ecosystem should be chosen in which one or more factors affecting the distribution of the chosen species varies. Sampling should be based on random numbers. In each quadrat the presence or absence of the chosen species should be recorded.

4.1.S4 Recognizing and interpreting statistical significance.

http://www.slideshare.net/gurustip/communities-and-ecosystems



4.1.U1 Species are groups of organisms that can potentially interbreed to produce fertile offspring.

Species is a group of organisms that can interbreed to produce fertile offspring

If species are not closely related it is often impossible for individuals of the different species to breed.

If members of two closely related species do interbreed and produce offspring the hybrids will be sterile e.g. mules.

https://i.ytimg.com/vi/8P01Y6LDwi0/maxresdefault.jpg



4.1.U2 Members of a species may be reproductively isolated in separate populations. AND 4.1.U7 A community is formed by populations of different species living together and interacting with each other.

Population is a group of organisms of the same species that are living in the same area at the same time.

Organisms of the same species separated geographically or temporally are unlikely to breed, though the ability to do so remains. The separated organisms are regarded as being members of different populations.

All organisms are dependent on interactions with members of other species for survival, e.g. a Lion depends on the availability prey species, such as Zebra and Antelope.

Community is a group of populations that are living and interacting together in the same area.

http://www.adventurewomen.com/wp-content/uploads/2015/04/WPanimals-at-watering-hole-at-Etosha.jpg

Communities also include plants and microbes and hence often involve thousands of species.



Review: 4.3.U1 Autotrophs convert carbon dioxide into carbohydrates and other carbon compounds. AND 4.1.U9 Autotrophs obtain inorganic nutrients from the abiotic environment.

http://commons.wikimedia.org/wiki/File:Plagiomnium_affine_laminazellen.jpeghttp://www.earthtimes.org/newsimage/photosynthesis-dream-renewable-energy_1_02842012.jpg

n.b. Although most autotrophs fix carbon by photosynthesis. A few are Chemoautotrophs and fix carbon by utilising the energy in the bonds of inorganic compounds such as hydrogen sulfide.

All autotrophs convert carbon dioxide (from the atmosphere or dissolved in water) into organic compounds.

Plant initially synthesis sugars (e.g. glucose) which are then converted into other organic compounds such as:• complex carbohydrates e.g.

starch, cellulose• lipids• amino acids

The inorganic nutrient compounds, e.g. water, carbon dioxide, nitrates, phosphorous and oxygen are obtained from the abiotic environment, whether it be the soil, air or water.

http://commons.wikimedia.org/wiki/File:Plagiomnium_affine_laminazellen.jpeg

http://commons.wikimedia.org/wiki/File:Plagiomnium_affine_laminazellen.jpeg

http://www.earthtimes.org/newsimage/photosynthesis-dream-renewable-energy_1_02842012.jpg

http://www.earthtimes.org/newsimage/photosynthesis-dream-renewable-energy_1_02842012.jpg

4.1.U3 Species have either an autotrophic or heterotrophic method of nutrition (a few species have both methods).

Autotrophs synthesise their own organic molecules and are therefore known as producers

All organisms require organic molecules, such as amino acids, to carry out the functions of life, for example metabolism, growth, and reproduction.

https://commons.wikimedia.org/wiki/File:Colpfl27a.jpg

Heterotrophs however obtain their organic molecules from other organisms

https://commons.wikimedia.org/wiki/File:Zebra_Grazing_%289659709105%29.jpg



https://commons.wikimedia.org/wiki/File:Zebra_Grazing_(9659709105).jpg



Nature of Science: Looking for patterns, trends and discrepancies - plants and algae are mostly autotrophic but some are not. (3.1)

https://commons.wikimedia.org/wiki/File:Venus_Flytrap_showing_trigger_hairs.jpghttps://commons.wikimedia.org/wiki/File:Euglena_sp.jpg

Euglena sp. is a genus of Algae that will photosynthesise (autotroph) in sufficient light, feeding as an autotroph, but can also ingest particles of food by phagocytosis, which it then digests (heterotroph)

Venus flytrap (Dionaea muscipula) is found in subtropical wetlands and like most plants photosynthesise (autotroph), but also traps and digests both insects and spiders (heterotroph), to compensate for the nutrient poor soil of the wetlands.

A few plants and algae use a combination of different modes of nutrition and are hence known as mixotrophs

https://commons.wikimedia.org/wiki/File:Venus_Flytrap_showing_trigger_hairs.jpg

https://commons.wikimedia.org/wiki/File:Venus_Flytrap_showing_trigger_hairs.jpg

https://commons.wikimedia.org/wiki/File:Euglena_sp.jpg

https://commons.wikimedia.org/wiki/File:Euglena_sp.jpg

https://commons.wikimedia.org/wiki/File:Zebra_Grazing_%289659709105%29.jpg

4.1.U4 Consumers are heterotrophs that feed on living organisms by ingestion.

Heterotrophs that ingest other organisms obtain their organic molecules are known as Consumers

Herbivores feed on producers (e.g. deer, zebra and aphids)

Consumers use a range of different food sources and feeding mechanisms. The combination of food source and feeding mechanism can be used to classify consumers.

Carnivores feed on other consumers (e.g. lions, snake and ladybirds)

Omnivores feed on a combination of both producers and consumers (e.g. chimpanzee, mouse)

https://commons.wikimedia.org/wiki/File:Lion_feeding_-_melbourne_zoo.jpg

Scavengers are specialised carnivores that feed mostly on dead and decaying animals (e.g. hyenas, vultures crows)

https://commons.wikimedia.org/wiki/File:Vulture_-_Sky_burial.jpg

https://commons.wikimedia.org/wiki/File:Gombe_Stream_NP_Jungtier_fressend.jpg













4.1.U5 Detritivores are heterotrophs that obtain organic nutrients from detritus by internal digestion.

Humus is decaying leaf litter mixed with the soil

Detritivores are a type of heterotroph that obtain nutrients by consuming non-living organic sources, such as detritus and humus

Detritus is dead, particulate organic matter. This includes decaying organic material and fecal matter

Examples of detritivores include dung beetles, earthworms, woodlice and crabs

https://commons.wikimedia.org/wiki/File:Earthworm.jpg



4.1.U6 Saprotrophs are heterotrophs that obtain organic nutrients from dead organisms by external digestion.

unlike most heterotrophs, saprotrophs are not consumers, as they do not ingest food: digestion is external as enzymes are secreted.

https://commons.wikimedia.org/wiki/File:Gelbstieliger_Nitrathelmling_Mycena_renati.jpg

Saprotrophs live on, or in, non-living organic matter. They secrete digestive enzymes on to the organic matter and absorb the products of digestion.

Examples of saprotrophs include bacteria and fungi

Because saprotrophs facilitate the breakdown of organic material, they are referred to as decomposers



4.1.S1 Classifying species as autotrophs, consumers, detritivores or saprotrophs from a knowledge of their mode of nutrition.

Which group of organisms in the carbon cycle converts carbon into a form that is available to primary consumers?

A. Decomposers

B. Saprotrophs

C. Detritus feeders

D. Producers

Classifying organisms based on their nutrition


Slime moulds (Acrasiomycota) are protoctists. They feed on decaying organic matter, bacteria and protozoa. Which of the terms describes their nutrition?

I. DetritivoreII. AutotrophIII. Heterotroph

A. I only

B. I and II only

C. I and III only

D. I, II and III



The scarlet cup fungus (Sarcoscypha coccinea) obtains its nutrition from decaying wood by releasing digestive enzymes into the wood and absorbing the digested products. Which of the following terms describe(s) the fungus?

I. AutotrophII. HeterotrophIII. Saprotroph

A. III only

B. II and III only

C. I and III only

D. I, II and III


4.1.S3 Testing for association between two species using the chi-squared test with data obtained by quadrat sampling. AND 4.1.S4 Recognizing and interpreting statistical significance.

Testing for associations between speciesspecies may be associated in different ways

Positive association Negative association No association

Species found in the same habitat.e.g. predator - prey, herbivore & plant, symbiosis

Species occur separately in differing habitats.e.g. competitive exclusion, require different nutrients

Species occur as frequently apart as together.


Testing for associations between species

Quadrat sampling can be used in a number of ways including:• Estimation of population density/size• Measuring the distribution of species

Quadrats are placed repeatedly in a sample area to provide a reliable estimate. Quadrats can be placed systematically, e.g. in a ‘belt transect’, typically to measure changing distribution, or randomly, e.g. to estimate population density. Depending on what is being measured either presence/absence, frequency or % coverage of a given species can be recorded. Both systematic and random sampling methods are used to avoid bias in the selection of samples.

The major limitation of quadrat sampling is that large and mobile animals cannot be effectively sampled. It is most suitable for plants and small, slow moving animals.


Data from: https://www.geography-fieldwork.org/ecology/hydrosere/4-data-analysis.aspxhttps://c1.staticflickr.com/9/8678/15983466342_62a12ba53d_b.jpg

https://en.wikipedia.org/wiki/Galium_elongatum#/media/File:Galium_elongatum_eF.jpg

Two continuous belt transects were taken from the edge of a lake to 25m inland. 1m2 quadrats were used making a total sample of 100 quadrats. The presence or absence of two species was recorded for each quadrat:

Within the 100 quadrats sampled, 12 contained both bottle sedge and marsh bedstraw, 3 contained only marsh bedstraw, 29 contained only bottle sedge, and 56 contained neither species.

Testing for the association between two species using the Chi-squared test

Bottle sedge (Carex rostrata) is a swamp plant

Marsh bedstraw (Galium elongatum) is found in ditches and wet meadows.

Is there an association between the two species?

https://www.geography-fieldwork.org/ecology/hydrosere/4-data-analysis.aspx



https://c1.staticflickr.com/9/8678/15983466342_62a12ba53d_b.jpg

https://c1.staticflickr.com/9/8678/15983466342_62a12ba53d_b.jpg

https://en.wikipedia.org/wiki/Galium_elongatum%23/media/File:Galium_elongatum_eF.jpg

https://en.wikipedia.org/wiki/Galium_elongatum%23/media/File:Galium_elongatum_eF.jpg


Data from: https://www.geography-fieldwork.org/ecology/hydrosere/4-data-analysis.aspx

Complete the contingency table of observed frequencies using the data provided:

Testing for an association between two species using the Chi-squared test

Observed values

Marsh bedstraw

present absent total

Bottle sedge

present 41

absent 59

total 15 85 100

Null hypothesis (H0): There is no significant difference between the distribution of two species (i.e. distribution is random)Alternative hypothesis (H1): There is a significant difference between the distribution of species (i.e. species are associated)

First step in statistics is ALWAYS to define the hypotheses

1

2






Complete the contingency table of observed frequencies using the data provided:


Observed values

Marsh bedstraw


Bottle sedge

present 12 29 41

absent 3 56 59

total 15 85 100


First step in statistics is ALWAYS to define the hypotheses

1

2







Observed values

Marsh bedstraw


Bottle sedge

present 12 29 41

absent 3 56 59

total 15 85 100Expected values Marsh bedstraw


Bottle sedge

present 41

absent 59

total 15 85 100

Calculate expected values using the formula: = row total x column total grand total

3


n.b. Expected values are what you would expect to be find if there is no association between the species.







Observed values

Marsh bedstraw


Bottle sedge

present 12 29 41

absent 3 56 59



Bottle sedge

present 6.15 34.85 41

absent 8.85 50.15 59

total 15 85 100

Calculate expected values using the formula: = row total x column total grand total

3


n.b. Expected values are what you would expect to be find if there is no association between the species.







Observed values

Marsh bedstraw


Bottle sedge

present 12 29 41

absent 3 56 59



Bottle sedge

present 6.15 34.85 41

absent 8.85 50.15 59

total 15 85 100


4

χ2 =

= (12 – 6.15)2 + … + (56 – 50.15)2

6.15 50.15

= 5.56 + 3.86 + 0.98 + 0.68

= 11.10

Calculate the Chi-squared value:







Observed values

Marsh bedstraw


Bottle sedge

present 12 29 41

absent 3 56 59



Bottle sedge

present 6.15 34.85 41

absent 8.85 50.15 59

total 15 85 100


5 Determine the degrees of freedom:

Degrees of freedom (df)= (rows* – 1) x (columns* –

1)= (2 - 1) x (2 - 1)= 1

n.b. for an association between two species df ALWAYS = 1

*not including totals







df p (% certainty)0.5

(50%)0.1

(90%)0.05

(95%)0.01

(99%)0.001

(99.9%)

1 0.455 2.706 3.841 6.635 10.827

2 1.386 4.605 5.991 9.21 13.815

3 2.366 6.251 7.815 11.345 16.268

4 3.357 7.779 9.488 13.277 18.465

5 4.351 9.236 11.07 15.086 20.517


6 Compare the χ2 value with the critical values and validate the hypotheses:

Critical values for the χ2 distribution

• It is usual to consider a result statistically significant at the 95% certainty (p <0.05) level.

• As df = 1 that means the H0 is rejected if X2 > 3.841

• Since 11.10 > 3.84 H0 is rejected and H1 is accepted: there is an association between Marsh bedstraw and Bottle Sedge.

n.b. In this case 11.10 > 10.827 we can go further and say that we are 99.9% certain there is an association between the two species.




4.1.U8 A community forms an ecosystem by its interactions with the abiotic environment.


Ecosystems consist of both the community and the

environment. The abiotic environment has a fundamental

impact on the community it supports. The community that

can exists in a sand dune ecosystem is very different from the

aquatic community in the adjacent sea.



4.1.U10 The supply of inorganic nutrients is maintained by nutrient cycling.

Nutrient cycling

The supply of nutrients is limited and therefore ecosystems constantly recycle the nutrients between organisms.

Elements required by an organism for growth and metabolism are regarded as nutrients, e.g. carbon, nitrogen and phosphorous.

• Autotrophs convert nutrients from inorganic form into organic molecules, e.g. carbon dioxide becomes glucose

• Heterotrophs ingest other organisms to gain organic forms of nutrients

• Saprotrophs breakdown organic nutrients to gain energy and in the process release nutrients back into inorganic molecules, e.g. fungi release nitrogen as ammonia into the soil. This ensures the continuing availability of nutrients to autotrophs.

http://www.ib.bioninja.com.au/_Media/nutrient-cycling_med.jpeg



4.1.U11 Ecosystems have the potential to be sustainable over long periods of time.

Ecosystems are sustainable

To remain sustainable an ecosystem requires:• Continuous energy availability, e.g. light from the sun• Nutrient cycling - saprotophs are crucial for continuous provision of nutrients to

producers• Recycling of waste – certain by products of metabolism, e.g. ammonia from excretion,

are toxic. Decomposing bacteria often fulfill this role by deriving energy as toxic molecules are broken down to, simpler, less toxic molecules.

Most flows of energy and nutrients in an ecosystem are between members of the biotic community. Relatively few flows of energy and nutrients enter or leave from surrounding ecosystems.

Therefore ecosystems are to a large extent self-contained and hence self-sustaining.

http://i.dailymail.co.uk/i/pix/2013/01/24/article-2267504-17212EB3000005DC-781_634x663. jpg

http://i.dailymail.co.uk/i/pix/2013/01/24/article-2267504-17212EB3000005DC-781_634x663.jpg



Mesocosms are biological systems that contains the abiotic and biotic features of an ecosystem but are restricted in size and/or under controlled conditions.


The restriction placed on mesocosms make them useful for scientific investigations where the uncontrolled nature of a natural ecosystems makes it difficult to collect meaningful data.

The mesocosm in the image has survived for 53 years since being sealed in the bottle: http://www.dailymail.co.uk/sciencetech/article-2267504/The-sealed-bottle-garden-thriving-40-years-fresh-air-water.html



http://www.dailymail.co.uk/sciencetech/article-2267504/The-sealed-bottle-garden-thriving-40-years-fresh-air-water.html

http://www.dailymail.co.uk/sciencetech/article-2267504/The-sealed-bottle-garden-thriving-40-years-fresh-air-water.html


Mesocosms are biological systems that contains the abiotic and biotic features of an ecosystem but are restricted in size and/or under controlled conditions.


Build your own mesocosm and blog the changes you observe:http://scribbit.blogspot.com/2010/05/kids-summer-crafts-build-ecosystem.html

Learn more about mesocosms developed for research:• The biosphere -

http://archive.bio.ed.ac.uk/jdeacon/biosphere/biosph.htm

• Ecotron - http://www3.imperial.ac.uk/cpb/history/theecotron



http://scribbit.blogspot.com/2010/05/kids-summer-crafts-build-ecosystem.html





http://www3.imperial.ac.uk/cpb/history/theecotron

http://www3.imperial.ac.uk/cpb/history/theecotron

Bibliography / Acknowledgments

http://ib.bioninja.com.au/

http://i-biology.net/

bioknowledgy presentation on 4.1 species, communities and ecosystems

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