Uniramia

Question 1

Myriapoda

Answer 1

All trunk segments are similar, bearing one/two pairs of walking legs.
Single pair of Malpighian tubules.
Consists of Centipedes and millipedes.

Question 2

Myriapoda: Class Chilopoda (centipedes)

Answer 2

Depressed
Elongate
Heads with 2 pairs of maxillae
15-181 leg bearing segments with similar legs
One pair of segments have poison claws
Sperm transfer is done via external spermatophore.

Question 3

Myriapoda: Class Diplopoda (millipedes)

Answer 3

Short elongate
Cylindrical
Most segments are diplosegments, with two pairs of limbs, ganglias, hearts
In males the anterior legs are modified for sperm transfer.
One pair of maxillae
All herbivores/detritivores
The only uniramia with calcified cuticle (calcium carbonate)

Question 4

Hexapoda (insects and relatives)

Answer 4

Most speciose of all taxa on earth, no consensus of the number of species.
Insects make up at least 58% of all described species on earth, dominating the terrestrial habitat.
Marine species are rare, and this is one habitat they have never successfully invaded.

Question 5

Why so many insects?

Answer 5

Fine grainedness of habitat, as small insects have a greater number of potential niches (spatial and ecological).
Have diversified into a huge range of feeding types.
With trachea can occupy anaerobic areas.
Excellent vision , mechanoreception and chemoreception, also very mobile due to sophisticated perception and motor responses.
Very rapid life cycles which allows for rapid selection, faster rates of evolution and local adaptation.
Well developed symbiosis and coevolution with plants.
Persistence of lineages, numerical abundance and size.
Possession of wings which helps predator avoidance, movement to new habitats, including isolated habitats where speciation may occur.
Metamorphosis, allows for the larvae and adult to exploit different resources of the habitat. The pupal stage can also act as a resting stage, during unfavorable times of the year.

Question 6

Atmospheric oxygen level and the evolution of insect body size.

Answer 6

Insects are small size is possibly due to limitations associated with their blind ended tracheal respiratory system.
Most insects develop smaller body sizes in hypoxia, and some develop and evolve larger sizes in hyperoxia.
Insects developmentally and evolutionarily reduce their proportional investment in the tracheal system when living in higher aPO2, suggesting that there are significant costs associated with tracheal system structure and function.
Larger insects invest more of their body in their tracheal system, potentially leading to greater effects of aPO2 on larger insects

Question 7

Cladogram

Answer 7

Phylogeny constructed on the process of using derived shared characters to define a group.

Question 8

Apomorphic

Answer 8

Derived characters, in contrast to primate/basal (pleisiomorphic) states of that character.

Question 9

Sister groups

Answer 9

Defined cladistically, and on basis of sharing the greatest number of derived characteristics, and sharing a recent common ancestor.