Selection pressures and information of shrublands PDF

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it's a great course, and the document is very helpful with understanding selection pressures and finding out information about shrublands...

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Module 3: Biological diversity Inquiry question: How do environmental pressures promote a change in species diversity and abundance? Predict the effects of selection pressures on organisms in ecosystems, including: - biotic factors - abiotic factors

Selection Pressures in an Ecosystem

Natural selection is the mechanism proposed by Charles Darwin and Alfred Wallace to explain how species change over time. This theory states that:1. There is variation in a population. Individuals are born with variations. 2. There is selecting pressure that allows individuals to be best suited to the environment. (survival of the fittest) 3. These individuals survive and reproduce, passing their variation onto their offspring. 4. Over time, the numbers of individuals with this variation will increase. https://www.youtube.com/watch?v=zeoBG2wDScg What is a selection pressure? Selection pressures are external agents which affect an organism's ability to survive in a given environment. Selection pressures can be negative (decreases the occurrence of a trait) or positive (increases the proportion of a trait).

Examples of selection pressures (see Pearson Biology p310 – p314) Abiotic factors Rainfall and water availability Light intensity and availability Temperature Topography Wind speed and direction Soil type Presence of pollutants and chemicals eg antibiotics, pesticides

Biotic Factors Availability and abundance of foods Competition for the same limited resources Predators and availability of prey Number and variety of disease-causing organisms Number of mates

Example of how abiotic factors have acted as selection pressures on the organisms living in an ecosystem. Australian tropical rainforests https://www.agriculture.gov.au/abares/forestsaustralia/profiles/rainforest-2016

Australia’s rainforests are typically characterised by high rainfall, lush growth and closed canopies. They rarely experience fire, and generally contain no eucalypts or only the occasional individual eucalypt tree emerging from the rainforest canopy. Rainforest tree species are shade-tolerant when young and establish in the understorey of mature forest. Abiotic factors: are high rainfall, low light, high temperatures and humidity. Plants that have adaptations to these conditions have been selected for.

Task: The Australian shrubland The Australian shrubland is an example of a common ecosystem found in Australia. Choose one organism that lives in the Australian shrubland and answer the following questions: a) Name the organism chosen including both its common name and scientific name. The organism chosen is a rabbit, and it’s common name is known as a European rabbit and its scientific name it Oryctolagus cuniculus. b) Describe the ecosystem in terms of the abiotic and biotic factors. The shrubland ecosystems abiotic factors would include the climate. The shrubland has many different characteristics and climates, for example the shrublands generally have hot, dry summers, and cool, moist winters. Another abiotic factor of shrublands is that there are fires. They often have fires caused by the lightening storms, because they have such little rain, and the plant are very flammable. Shrublands generally have mostly nutrient poor soil, which means there aren’t any large trees. The biotic factors of a shrubland are usually primary consumers that live their and have very varied diets of grasses, leaves, and shrubs to sustain themselves, and animals are often small and burrow to avoid the sun’s extreme heats. Plants often have waxy coatings on their leaves to maintain moisture.

c) Identify and justify which factors may have acted as selection pressures on the organism you have chosen. Some of the factors that may have acted as selection pressures on rabbits in shrublands could be the temperature and climate that they are living in, the food sources they have around them, and maybe diseases carried by predators and pathogens. The Australian shrubland...