Body condition and head size in snakes

Abstract

On several occasions during my many years of working with various snake species, I observed a significant positive relationship between body condition and head size (the former calculated from residual scores from a general linear regression of ln-transformed mass on ln-transformed snout-vent length). Based on results from my long-term study of water pythons (Liasis fuscus) this relationship is, however, most likely caused by a condition-dependent bias when recording snake snoutvent length (SVL). Water pythons in good condition were recorded as being "shorter" and hence having relatively larger head size, whereas snakes in poor condition were recorded as being "longer" with concomitant smaller head relative head size. Such a systematic bias may lead to spurious conclusions concerning the adaptive significance of the relationship between snake body condition and head size.

No signs of Na+/K+‐ATPase adaptations to an invasive exotic toxic prey in native squamate predators

“…Alignment of the 36 nucleotides constituting the H1-H2 extracellular loop of the alpha-3 subunit of the Na + /K + -ATPase gene in red-bellied snakes and yellow spotted goannas. Madsen 2011). Since snakes are gape-limited predators their maximum ingestible prey size is dependent on their head size (e.g.…”

“…Since snakes are gape‐limited predators their maximum ingestible prey size is dependent on their head size (e.g. Madsen ). Consequently, red‐bellied black snakes with relatively larger heads would stand a greater risk of ingesting a large cane toad (with fatal consequences) compared to snakes with a smaller head size.…”