Poster Session I
Head size allometry supports differences in digging ability between sexes in a semi-fossorial lizard
Project Type
Poster
Faculty Mentor’s Full Name
David Tevs
Faculty Mentor’s Department
Division of Biological Sciences
Abstract / Artist's Statement
In lizards, sexual dimorphism in head shape has commonly been studied from a male perspective, with larger heads being associated with greater fighting ability during male-on-male combat or for displaying colored throats. However, reductions in overall head size and length are also associated with adaptation to a fossorial lifestyle. Consequently we hypothesize that reduced female head size in sub-surface nesting lizards may also confer greater digging ability and provide greater freedom when selecting suitable nest sites. We collected western skinks (Plestiodon skilontianus) by turning rocks on dry-pine slopes in the Bitterroot National Forest (Montana, USA). For each lizard, we recorded snout-vent length and head length, width and height. We also recorded the embedded depth of rocks we found observed lizards under. After correcting for differences in body size, the head width, length and height of female lizards were smaller than that of males. Female head length and width, but not height, also grew at a slower rate relative to body size compared to males. Finally, although the average embedded depth for both sexes was similar, female embedded depth measurements were more variable and had a larger maximum depth than that of the males. These findings support reduced head size in female lizards beneficial for accessing a wide range of nesting depths and suggest that selective pressures acting on lizard head shape differ between sexes.
Category
Life Sciences
Head size allometry supports differences in digging ability between sexes in a semi-fossorial lizard
UC South Ballroom
In lizards, sexual dimorphism in head shape has commonly been studied from a male perspective, with larger heads being associated with greater fighting ability during male-on-male combat or for displaying colored throats. However, reductions in overall head size and length are also associated with adaptation to a fossorial lifestyle. Consequently we hypothesize that reduced female head size in sub-surface nesting lizards may also confer greater digging ability and provide greater freedom when selecting suitable nest sites. We collected western skinks (Plestiodon skilontianus) by turning rocks on dry-pine slopes in the Bitterroot National Forest (Montana, USA). For each lizard, we recorded snout-vent length and head length, width and height. We also recorded the embedded depth of rocks we found observed lizards under. After correcting for differences in body size, the head width, length and height of female lizards were smaller than that of males. Female head length and width, but not height, also grew at a slower rate relative to body size compared to males. Finally, although the average embedded depth for both sexes was similar, female embedded depth measurements were more variable and had a larger maximum depth than that of the males. These findings support reduced head size in female lizards beneficial for accessing a wide range of nesting depths and suggest that selective pressures acting on lizard head shape differ between sexes.