On Mon, 10 Sep 2001 wrote:
> By the way, what was the basis for Schodde's differentiation between the
> races / species?
Here are the six criteris given by Schodde & Mason:
(i) by the criterion of treating groups of ultrataxa as species
(ii) their differences (morphological) are as great or greater tha
other allospecies of Psophodes
(iii) there is no confirmed intergradation between where they abut
(iv) two traits presumed possibly intergradient by Schodde & Mason -
dorsal tone and tail patterning - are, on reassessment doubtfully so
(v) the black line above the white malar stripe shared bya dult
ingrogularis and WA leucogaster and present in erratic traces in SA populations,
is evidentally ancestral and of little phylogentic and
taxonomic significance at this level
(vi) other traits of WA leucogaster, on the contray, are the most divergent of
all from nigrogularis, particularly size, proportion (long tail) and
ventral toning
On the subject of calls, basic evolutionary biology would suggest if the
Two People's Bay population is nigrogularis you would expect significant
differences between their calls and nearby leucogaster populations,
assuming calls are an important isolating mechanism - and for Whipbirds, a
cryptic fairly sombre species with complex calls, this would seem likely.
I guess significant (to Whipbird) differences would be apparent to human.
The converse doesn't follow - differences in calls between populations
which are apparent to humans, may not be significant to the birds, and
hence not an isolating mechanism. Hence, there can be regional dialects
in the songs of single species.
Andrew Taylor
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