How inclines affect the escape behaviour of a dune-dwelling lizard, Uma scoparia.
نویسندگان
چکیده
Although previous laboratory studies have commonly determined sprinting speeds of lizards on horizontal surfaces, the speeds and slopes used during the escapes of lizards in natural habitats with variable inclines are virtually unstudied. To quantify performance and the use of inclined surfaces during escape, we took advantage of the footprints left in soft substrate and the simple surface topography of the natural dune habitat of the Mojave fringe-toed lizard, U. scoparia. The lengths of 52 escape paths ranged from 1.7-34 m, and the inclines of 1-m portions of escape paths ranged from -25 degrees to 28 degrees, which effectively encompassed the entire range of inclines in the habitat. The cumulative frequencies (N=550) of inclines along 1-m intervals of the escape paths were not a simple random sample of the habitat. Less than 10% of the cumulative distance travelled during escape was bipedal, and the escape paths were relatively straight. Trajectories of the first metre of escapes were oriented significantly away from the presumed threat (observer) but were random with respect to the orientation of both the nearest cover and steepest incline. Eleven per cent of the cumulative number (N=1382) of strides measured were within 90% of the maximum stride length within each path. Multiple regressions revealed that stride lengths (and hence speed) during escapes in the field were maximized on level surfaces with no turning. For lizards tested on a level racetrack in the laboratory, maximum speeds averaged 2.8 m/s (range=2.1-3.9) and approximated 75% of the maximum performance attained in the field.Copyright 1998 The Association for the Study of Animal Behaviour. Copyright 1998 The Association for the Study of Animal Behaviour.
منابع مشابه
A field study of the effects of incline on the escape locomotion of a bipedal lizard, Callisaurus draconoides.
We analyzed footprints on the surface of a sand dune to estimate maximal running speeds and the incidence of bipedality in nature, as well as to investigate the effects of incline on the escape locomotion of the lizard Callisaurus draconoides. Previous laboratory tests predicted that inclines would negatively affect sprinting performance in C. draconoides. Although physiologists commonly assume...
متن کاملSpeciation, population structure, and demographic history of the Mojave Fringe-toed Lizard (Uma scoparia), a species of conservation concern
The North American deserts were impacted by both Neogene plate tectonics and Quaternary climatic fluctuations, yet it remains unclear how these events influenced speciation in this region. We tested published hypotheses regarding the timing and mode of speciation, population structure, and demographic history of the Mojave Fringe-toed Lizard (Uma scoparia), a sand dune specialist endemic to the...
متن کاملEnvironmental differences in substrate mechanics do not affect sprinting performance in sand lizards (Uma scoparia and Callisaurus draconoides).
Running performance depends on a mechanical interaction between the feet of an animal and the substrate. This interaction may differ between two species of sand lizard from the Mojave Desert that have different locomotor morphologies and habitat distributions. Uma scorparia possesses toe fringes and inhabits dunes, whereas the closely related Callisaurus draconoides lacks fringes and is found o...
متن کاملEffects of incline on speed, acceleration, body posture and hindlimb kinematics in two species of lizard Callisaurus draconoides and Uma scoparia.
We examined the effects of incline on locomotor performance and kinematics in two closely related species of iguanian lizards that co-occur in sandy desert habitats. Callisaurus draconoides differs from Uma scoparia of equal snout-vent length by being less massive and having greater limb and tail lengths. We analyzed high-speed video tapes of lizards sprinting from a standstill on a sand-covere...
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ورودعنوان ژورنال:
- Animal behaviour
دوره 55 5 شماره
صفحات -
تاریخ انتشار 1998