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
Physical differences Voice

Song/Calls

Habitat preference
Behaviour
including
migration
Known
genetic differences

Assuming a rate of divergence in mtDNA of 1.6–2.0% per million years. (Fleischer et al.1998; also see Lovette 2004; Ho 2007; Weir and Schluter 2008).

From mtDNA analysis, species take from between 0.2 to 5.5m yrs.  ("The Speciation & Biogeography of Birds", Ian Newton, 2003.

MU

Total points
sp
or
subsp

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

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 mtDNA and other genetic 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, or successful breeding is not known to occur where there is breeding overlap.


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.
Genetic differences are barely measurable.


Genetic
differences are definitely measurable.



Genetic differences indicate larger divergences.

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


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




Trans-Berringian passerines
Comparison of a Universally Accepted Species with Other Taxon such as a Subspecies
 Geographic separation/Chance
of cross-breeding

Physical differences
Voice

Song/Calls

Habitat preference

Behaviour
differences

Genetic differences

Total Points
sp
or
subsp
These three taxa are mentioned in "The Speciation and Biogeography of Birds", Ian Newton, 2003, p 317, as having marked genetic differences from one side of Bering Strait to the other (Zink et al.1995).
Research -
Pica pica
Eurasian Magpie
Pica hudsonica Black-billed Magpie

Anthus rubescens American Pipit
Anthus r. japonicus Buff-bellied Pipit

Leucosticte arctoa Asian Rosy Finch
Leucosticte tephrocotis Gray-crowned Rosy Finch
Conclusions -
These three taxa show marked genetic differences (Zink et al. 1995); WL thinks this warrants a genetic divergence score of 2.
Although L. tephrocotis has an endemic subspecies on Commander Island, nearest to Kamchatka, and A. r. japonicus has populations on Commander and Ostrova (not too far from the Aleutians), WL thinks a geographic separation of 2 is still justified.
The reason that A. r. japonicus does not make species level is that there are no obvious reproductive differences in any of the other four criteria and chances of cross-breeding are quite good. IOC agrees :)   






0
2

0
1-2

0
2





0
0

0
0

0
1





0
1

0
0

0
0







0
0

0
0

0
0










0
0

0
0

0
0









0
2

0
2

0
2









0
5

0
3-4

0
5






sp

sp

sp
subsp

sp
sp