Enquiry Question 1 Defining Biodiversity What is the nature and value of biodiversity? Learning Objectives – * To know & understand what ‘biodiversity’ is * To be able to explain the three ways in which biodiversity can be measured * To evaluate the advantages and disadvantages of each measure
TASK: Look at the words around the room – and come up with 2 sentences that define the word ‘biodiversity’ Biodiversity There are 3 measures of biodiversity!! Answer: Biodiversity is the degree of variation of all life forms – plants, animals and microorganisms – within a given place. It is the main measure of health for biological systems, like ecosystems.
Genetic Diversity Genetic diversity is the range of species found within a species. This means that it refers to the total number of genetic characteristics within the DNA of a species.
Genetic variation in Giraffes http: //www. bbc. co. uk/lear ningzone/clips/6244. html http: //www. youtube. com/ watch? v=y 4 b. Icsw. VZMU Why is genetic variation important? Example – Giraffe or you can use Darwin’s finches with their different beaks Task: Watch the clip, then describe how genetic variation has helped this species to survive and adapt
Genetic variation in Giraffes Model answer: 1. Genetic variation exists among individuals within giraffes – some have short necks like a horse, others have slightly longer necks. 2. All the giraffes have competition for resources (food and space) 3. This competition would lead to the death of some individuals (mainly shorter necked ones, as their food is also eaten by all the other short necked animals). Whereas others would survive (the longer necked ones have an advantage as they can reach the juicy leaves at the top!) 4. Individuals that have advantageous variations are more likely to survive and reproduce.
Therefore, it is important because… • Genetic diversity and biodiversity are dependent upon each other – genetic diversity within a species is necessary to maintain biodiversity. • Genetic diversity plays a very important role in survival and adaptability of a species because when a species’ environment changes, slight gene variations are necessary for it to adapt and survive. A species that has a large degree of genetic diversity among its population will have more variations from which to choose the most fit genes. • Species that have very little genetic variation are at a great risk. With very little gene variation within the species, healthy reproduction is difficult. Task: Sum the above up into only 2 sentences in your own words!!
Species Diversity Species diversity is the range between different species. Commonly given via the Simpson's Diversity Index: D = (n / N)2 n = species abundance (the total number of organisms of a particular species; which shows how common or rare they are relative to other species in the same area) N = species richness (the number of organisms of all species in an area) A value of 0 indicates infinite diversity, a value of 1 indicates no diversity
• Why are species diversity important!? • The Bio Da Versity Code! • http: //assets. panda. org/custo m/flash/daversitycode/ http: //www. youtube. com/watc h? v=BXXcz. Lhzl. HA • TASK: What is meant by the ‘web of life’ and how does it show the importance of species diversity? Watch the clip carefully then draw a diagram to support your answer.
Ecosystem Diversity Ecosystem diversity is the interdependence and interactions of species within their environments. This refers to the diversity of a place in terms of its variety of ecosystems or habitats i. e. what is the diversity of different ecosystems within the UK, as opposed to the diversity of species within these ecosystems. Task: Describe and compare two continent examples – what ecosystem diversity do they have?
Advantages GENETIC Diversity SPECIES Diversity ECOSYSTEM Diversity Disadvantages
Advantages Disadvantages GENETIC Diversity • Allows an accurate picture of diversity within a population (2) • Helps explain how isolated species eg birds have adapted to new environments (10) • Difficult to assess without high level biological skills as DNA is required (11) SPECIES Diversity • A good general measure (4) • Better to use a range of indicator species (8) • Better to use taxonomic diversity eg 1 rodent, 2 bird, 1 lizard species = better than 4 bird species (7) • Must compare similar sized areas for a fair test (3) ECOSYSTEM Diversity • A more complex measure as it considers the interaction of species within their environment (1) • Possibly more useful when deciding which areas to protect as has a wider focus (5) • Difficult to know where the boundary of the ecosystem is (6) • Must compare similar sized areas for a fair test (3) • Species richness does not cover species distribution or interaction between species • (9)
Vote Which measure is the best and why: • Genetic diversity? • Species diversity? • Ecosystem diversity?