4.1 Biodiversity in ecosystems


4.1.1: Define the term biodiversity, genetic diversity, species diversity and habitat diversity.

  • Biodiversity: The number and variety of organisms found within a specified geographic region
  • Genetic diversity: the number of different and variation of genes in a genetic pool
  • Species diversity: the number of different and variation of species in a region
  • Habitat diversity: the number of different variation of habit in a region

http://sciencebitz.com/?page_id=27 (More info)

4.1.2: Outline the mechanism of natural selection as a possible driving force for speciation.


Natural Selection: where some species are more adapted to their environment and have an advantage in times of change. Their genes are passed onto future generation.
Environment change gives new changes to the species, those that are suited survive, those that are not will not.
Natural selection is an evolutionary driving force, sometimes called 'survival of the fittest'. (Fittest: the best suited to the niche)Natural selection is one of the main methods in which speciation occurs through the following steps
  • Within a population of one species there is genetic diversity, which is called variation
  • Due to the natural variation some individuals will be fitter than others
  • Fitter individuals have an advantage and will reproduce more successfully
  • The offspring of fitter individuals may inherit the genes that give the advantage
Due to the process of natural selection over generations there is a movement towards fitness in the whole population, the environment constantly selecting for the individuals that are best suited to that niche. Negative changes lead to extinction.


http://evolution.berkeley.edu/evosite/evo101/VSpeciation.shtml (Further reading)

4.1.3: State that isolation can lead to different species being produced that are unable to interbreed to yield fertile offspring

Speciation: the formation of species through gradual change over time
Depended on:
  • isolation of species
  • change of environmental
  • change of gene pool
Isolation: the process by which two populations become separated by:
  • Geographical factors: island formation, loss of land bridges and mountain ranges
  • Behavioral factors: reproductive displays, songs, daily activity
  • Genetic factors: inability to produce fertile offspring due to genetic different
  • Reproductive factors: anatomical different especially in reproductive organs

All these Lead to speciation



external image isolation.jpg


4.1.4: Explain how plate activity has influenced evolution and biodiversity

Plate activity

  • Collide of land: new mountain, meaning change of climate and formation of new haibitat
external image tectonics-collide.jpg
  • Subduction: creation of volcanic activity and island which could also change the climate.
external image Subduction1.gif
--Change in climate and creation of new habitat cause speciation

Plate activity could also lead to:
  • separation of gene pools
  • formation of physical barriers and land bridges


http://en.wikipedia.org/wiki/Plate_tectonics (Background knowledge)


4.1.5: Explain the relationships among ecosystem stability, diversity, succession and habitat.


  • "A complex ecosystem with its variety of nutrient and energy pathways provides stability"
  • Stability lead to diversity
  • Succession: increase in species diversity as there are new habitats been formed and a more complex ecosystem had been formed
  • human activities modify succession, for example, logging, grazing, burning
  • Greater habitat diversity leads to greater species and genetic diversity
  • an ecosystem’s capacity to survive change may depend on diversity, resilience(how well the system can return to the starting position) and inertia (how hard it is to move the system to a new position)
  • human activities often simplify ecosystems, rendering them unstable