form and function

Question 1

why do insects have six legs

Answer 1

stability, points of contact in climbing, climbing in a fractal world

Question 2

what is natural selection

Answer 2

the process whereby organisms better adapted to their environment tend to survive and produce more offspring.

Question 3

what is evolution

Answer 3

Over time selection produces genes that increase fitness in particular environments

Question 4

what is an adaptation of a butterfly

Answer 4

• butterfly proboscis- for feeding on tubular flowers
• wings for flight

Question 5

what are the coconut crabs adaptations

Answer 5

the claws

Question 6

what are the questions to test for an adaptation

Answer 6

• is the trait heritable
• is it functional
• does the trait increase fitness
• evolutionary history can help

Question 7

what are non adaptive explanations for traits

Answer 7

1. chance events
2. by product of another characteristic
3. biophysical constraint or default arrangement
4. they could be a product of genetic drift

Question 8

what are some of the features of body plans in invertebrates phyla ?

Answer 8

skeletons
symmetry
segmentation
body cavities

Question 9

what is the trade off theory

Answer 9

This theory suggests that you can’t as an organism be good at everything all of the time. The range in the diversity of the invertebrate forms reflect the diversity of life styles

Question 10

what are the trade off in shell morphology

Answer 10

in freshwater snails if they are round they are crush resistant however they are more susceptible to the entry of predators. Elongate shape is more resistant to predators but they are more likely to be crushed.

Question 11

what does the cross sectional area in worms determine ?

Answer 11

determines the resistance to burrowing. Being long and thin is a win as they are low resistance and they have opportunities to have a high pushing strengths and they can have lots of legs and muscles.

Question 12

what is the Reynolds number?

Answer 12

Re: the ratio of inertial to viscous forces in fluid. When re is high we tend to see turbulent flow but when it is low the fluid motion is more smooth or laminar

Question 13

Re=?

Answer 13

length X relative fluid velocity / viscosity

Question 14

what is the outcome of evolution

Answer 14

• diversity of organisms
• over 99% already extinct
• organised ways of organising and classifying

Question 15

what is taxonomy

Answer 15

the scientific study of naming, defining and classifying groups

Question 16

what is phylogeny

Answer 16

study of the history and relationship between organisms

Question 17

what is the Linnaean system- hierarchical classification

Answer 17

• Genera contained within families
• Taxon is the taxonomic unit at any level of the hierarchy
• Genera and species name always written in italics
• Higher taxa have capitals, Latin binomials are comprised of genus and species name

Question 18

what does the Linnaean system consist of

Answer 18

• Kingdom
  
  • Phylum
  • Class
  • Order
  • Family
  • Genus
    
    • Species

Question 19

what are clades

Answer 19

ancestral species and all its decedents

Question 20

how are clades nested

Answer 20

Clades can be nested within larger clades

Question 21

what is a taxon

Answer 21

equivalent to a clade if its monophyletic ( a group composed of the most common recent ancestor and all of the recent descends of it)

Question 22

what are phylogenies made up of

Answer 22

Made up of branches and nodes

Question 23

what does polytomy mean?

Answer 23

more than 2 lineages diverge from a single nodes

Question 24

what are sister taxa

Answer 24

share and immediate common ancestor

Question 25

what is a Monophyletic group

Answer 25

ancestorial species and all its decedents

Question 26

what is a Paraphyletic group

Answer 26

ancestorial species and some of its decedents

Question 27

what is a Polyphyletic group

Answer 27

taxa with different ancestors

Question 28

what is convergent evolution

Answer 28

Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time. Appear similar but will have different internal anatomy and physiology

Question 29

why is molecular data important when it comes to phylogenies

Answer 29

Molecular data can revise phylogenies and provider a deeper understanding

Question 30

What phylogenetic trees do not tell us:

Answer 30

1. Sequence of branching does not indicate age 2. If trees are based on morphology/ anatomy the branch lengths do not indicate time 3. Cannot assume a taxon evolved from the taxon next to it e.g. humans did not evolved from chimps

Question 31

what are molecular clocks

Answer 31

means of dating the divergence of organisms by looking at the changes in the structure of basic proteins or DNA

Question 32

what are the assumptions about mutations

Answer 32

- they accumulate randomly - the number of changes is proportional to time since divergence from the common ancestor

Question 33

how are molecular clocks calibrated

Answer 33

by measuring the differences between the genes in different groups that diverged at a known point (using fossils or geological data)

Question 34

what are the problems with molecular clocks

Answer 34

1. Regularity of change over time thought to be due to genetic drift. This is a random accumulation of mutations with little effect on fitness 2. Only ticks regularly for mutations that are neutral 3. DNA regions under strong neutral selections are not neutral and not good for phylogenies 4. Clock rate can vary between taxa and different regions of trees