Concepts and definitions

1. The evolution and emergence of new species

Answer: The evolution and emergence of new species

2. What is a tectonic plate?

Answer: Contiguous masses of the Earth’s crust and upper mantle

3. Explain two meanings of species radiation.

Answer: Evolutionary radiation: occupation of new territories by groups of individuals prior to colonization and eventual emergence of new species variants. Adaptive radiation: all forms of species diversification associated with the occupation of new or expanded ranges.

4. Define migration.

Answer: The five assumptions of Hardy–Weinberg equilibrium are:

5. What are peristalsis and undulation in the context of animal movement?

Answer: Peristalsis: movement of body mass by successive muscular squeezing of body material against a resistive external surface. Undulation: movement of body mass by sequential wave-like motions of the body in a vertical or horizontal plane.

6. Define aerofoil lift and drag and distinguish between laminar and turbulent flow in a fluid.

Answer: Lift: upward vector resulting from differential surface pressures. Drag: frictional resistance to movement through a fluid. Laminar flow: flow by essentially linear movement of fluid particles (particle positions in time are theoretically predictable). Turbulent flow: flow by chaotic movement of fluid particles (particle positions in time are unpredictable).

Apply the concepts

7. Explain how island isolation might influence speciation.

Answer: Separation of a subgroup of a population, due to island isolation, leading to the formation of new species

8. Why is it advantageous for plants to exploit moving features of their environment (fluids, animals)?

Answer: Allows for the distribution of seeds, fruits, and other tissues over a wider range than would normally occur, leading to the colonization of new areas and greater potential for cross-fertilization.

9. What limits the speed at which an elephant can run?

Answer: Maximum mechanical forces sustainable by limb bones; limiting inertial forces and musculature; limiting cardiac output and oxygen availability to musculature; and limiting rate of metabolic heat dissipation.

10. Explain why some birds and insects flap their wings.

Answer: Initiating and/or sustaining air movement over the wing to obtain lift and thrust and to maintain hovering

11. Explain how bird wings have evolved to avoid the effects of the boundary layer of air.

Answer: Feather covering creates an unstable surface which disperses the boundary layer. Some wing movements also cause the boundary layer to roll down the wing surface, reducing loss of lift and risk of stalling.

12. Explain how fish body surfaces have evolved to avoid the effects of the boundary layer of water.

Answer: Scales and skin denticles deflect the boundary layer and reduce drag caused by movement through a relatively viscous medium.

Beyond the concepts

13. Using a ruler or tape, measure the likely pendulum components in one of your legs. Also measure your stride length when a) walking and b) running at different speeds. Explain how the same leg dimensions allow you to move at different speeds.

Answer: Features personal measurements. Includes variations in stride length and frequency; transition from walking (constant ground contact) to running (leap/jump between steps).

14. Look out of the window or stand outside. For the next bird you see, roughly sketch its wing shape and decide the most likely nature of its flight pattern(s). If the bird is flying, compare your conclusion with what you observe.

Answer: Includes sketch of wing shape for a selected bird. Use Figures 31.41 and 31.42 to relate shape to flight pattern.

15. Eucalyptus trees are endemic to Australasia and other regions of the Southern hemisphere but not to the Northern hemisphere. Why might this be?

Answer: Most eucalypts are intolerant of the cold temperatures and frosts common to higher Northern latitudes. Many also require repeated, occasional exposure to fire in order to flourish. Some eucalypts can grow in the Northern hemisphere, but largely as a result of human intervention, selection, and cultivation.

16. Using online resources, obtain some information on the history and distributions of the white-clawed crayfish (Austropotamobius pallipes) and the signal crayfish (Pacifastacus leniusculus) in the UK. Would you describe each of these species as native or alien? What reasons could be used to argue for or against your conclusions?

Answer: The origin of white-clawed crayfish and its first occurrence in the UK is not known, but its sustained historical presence leads to it being considered “native”. The signal or American crayfish was introduced to the UK at the end of the 20thcentury. It out-competes the white-clawed crayfish and is therefore considered to be non-native/alien and invasive. These are subjective descriptors, which give weight to interpretations of historical rights, biodiversity values, and even nationalism and chauvinism. The success or otherwise of a species, and its displacement by another, are ecological events reflecting the phenotypes of the organisms involved. Human activity may, however, be an important environmental variable

17. Would it be correct to describe the European eel (Anguilla anguilla) as a migratory fish? What is its life story and what determines its global location at different times of year?

Answer: European eels undergo and extend migration as part of their complex life cycle. Spawn are produced at sea (especially the Sargasso Sea) and develop into larvae that transform into “glass eels” as they drift towards continental river systems. In brackish and fresh water, they transform into elvers, which then mature into the fully adult form over a long period (5–20 years). Adults return to the sea for mating and spawning.

18Charles Darwin was interested in the movement of plant seeds around the world in ocean currents and the importance of this for plant distribution. How did he attempt to find out about this?

Answer: Charles Darwin asked travellers to make observations and bring back, or post back to him, specimens of plants and seeds, which he then plotted against known ocean currents. He also experimented with the buoyancy of seeds in sea water and the effect of sea water exposure on the seeds’ germination.

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