Arthropod success Flashcards
What are the four main factors of Arthropod success?
- Biodiversity
- Ecological range
- Ecological importance
- Historical persistence
How is body size a reason for arthropod success?
Organisms range in over 8 orders of magnitude. Intermediate organisms, such as arthropods (around 3mm) dominate as there are more ecological niches for such intermediate sized organisms
How are speciation rates a reason for arthropod success?
Numbers of species in a group is a balance between speciation and extinction:
- Large organisms tend to be good dispersers = lowers likelihood of allopatric speciation
- Very small organisms also tend to be good dispersers = lowers likelihood of allopatric speciation
How is an arthropod’s cuticle a reason for arthropod success?
- Provides skeletal support
- Relatively impermeable to water
- Cuticle has proved uniquely flexible
Why is the skeletal support from the cuticle beneficial?
As it is especially important in colonisation in land : water is 1,000 times denser than air
Why is the cuticle being relatively impermeable to water important?
- It maintains homeostasis, especially avoiding desiccation on land
- due to epicuticular waxes, the rate of water loss is as low as 0.01% of that in soft bodied organisms such as the land snail Helix.
Why is it important that the cuticle is uniquely flexible?
Its segments and their appendages are modified in a variety of ways both within and between individual arthropod types
Why is an arthropod’s flexible bauplan important?
- Due to tagmosis and regional specialisation.
- The arthropod bauplan has undergone various forms of regional specialisation – most arthropods have bodies composed of functionally specialised regions (e.g. head, thorax, abdomen)
- Modification of appendages
What is true of Arthropods’ historical persistence?
Arthropod world domination has persisted since (before) the ‘Cambrian explosion’ (540MY)
What percentage of extant species do arthropods account for?
Around 70%
