Table 1.

Hypotheses pertaining to the strength and nature of abiotic versus biotic range limitation, their expected ecological outcomes, the tests performed in this study and predicted region of limitation.

ID	name (the ‘…’ )	hypothesis (‘…states that…’ )	ecological outcome (‘…resulting in…’ )	test of outcome (‘…evidenced by…’ )	predicted region of limitation (‘…in…’ )
abiotic predictions
A1	species-interactions/abiotic stress hypothesis	increased temperature fluctuations impose thermoregulatory stress	thermal niche tracking	greater thermal niche overlap	seasonal environments (western Himalayas)
A2	climatic variability hypothesis	decreased seasonality limits adaptation to variable temperatures	thermal niche tracking	greater thermal niche overlap	aseasonal environments (eastern Himalayas)
A3	thermoregulatory capacity hypothesis	smaller species, given poorer thermoregulatory capacity, are more strongly limited by abiotic factors than larger species	thermal niche tracking	negative correlation between body size and thermal niche overlap	all environments; stronger in the region where abiotic factors more important
biotic predictions
B1	species-interactions/abiotic stress hypothesis	increased species richness enhances competitive interactions	competitive exclusion	lower congeneric niche overlap	aseasonal environments (eastern Himalayas)
B2	ecological similarity hypothesis	competition increases with greater ecologically similarity between species	competitive exclusion	positive correlation between congeneric body size differences and congeneric niche overlap	all environments; stronger in the region where biotic factors more important
abiotic–biotic prediction
AB	resource availability hypothesis	competition increases in resource-scarce periods, and relaxes in resource-abundant periods	competitive exclusion	lower congeneric niche overlap in resource-limiting season	all environments; stronger in the region with greater seasonality (western Himalayas)