AASAGACITY.NET
  Knowledge is Empowering
A scoring system to define a species; an evaluation of a taxon/some taxa, using the Sensible Species Definition. 5 points between taxa makes a different species.



Geographic separation/Chance
of cross-breeding
Morphological and plumage differences Voice

Song/Calls

Habitat preference
Behaviour
including
migration
Known
DNA differences

Total Points
sp
or
subsp

Scoring 0-1-2-3 0-1-2-3 0-1-2-3 0-2-3-4 0-1-2-3 0-2-4-5

A SENSIBLE SPECIES DEFINITION (Anderson 1998 and 2012)
Species are populations that are interbreeding and which are reproductively isolated from other such populations by their reproductive isolating mechanisms.
These may include -
     geographic separation / chance of cross-breeding;
    morphological and plumage differences;
    voice;
    habitat preference;
    behavioural differences such as nest-building, social grouping or migration;
    consistent DNA differences.
Each mechanisms can be weighted according to the strength of difference from a recognised species and given a score between 0 and 5; a total of 5 would give the taxon species status.
0





1






2




3




4





5




Broad hybrid zone





e.g. Narrow and stable hybrid zone,
or good chance of interbreeding.


e.g A small chance of interbreeding.



No chance of interbreeding.

Feather tracts and/or bare parts a little different,



Feather tracts and/or bare parts noticeably different,


Feather tracts and/or bare
parts very different.

Feather tracts and/or bare
parts completely different.
Not so different voice range and/or song phrases.





Noticeably different voice range and/or song phrases,





Completely different voice range and/or song phrases.
Similar or slightly different habitat preferences.





Noticeably different habitats.







Completely different habitats.
Slightly different behaviour.






Noticeably different behaviour.






Very different behaviour.
DNA differences are barely measurable.



DNA differences are measurable.




DNA differences are larger.



DNA differences are large enough to probably have non-viable offspring.




DNA differences are so great that viable inter-breeding would be impossible.




Psophodes
Comparison of a Universally Accepted Species with Other Taxon such as a Subspecies
 Geographic separation/Chance
of cross-breeding
Morphological and plumage differences Voice

Song/Calls

Habitat preference

Behaviour
differences

DNA differences

Total Points
sp
or
subsp
Research -
Psophodes c. cristatus
              Chirruping Wedgebill
Psophodes c. occidentalis           Chiming Wedgebill

Psophodes olivaceus              Eastern Whipbird
Psophodes nigrogularis         Western Whipbird

Conclusions -
Although the total of small differences add up significantly,  cristatus and  occidentalis seem to be the same species,
Psophodes cristatus.
Psophodes olivaceous & Psophodes nigrogularis are different species as most people would expect.

0
1

0
2

0
0

0
2

0
1-2

0
1-2


0
0

0
1-2




0
1

0
0




0
0

0
0




0
3-4

0
6-8






sp
subsp

sp
sp