Spatial and Temporal Patterns of Activity


Lizards -- nearly "ideal" animals for ecological studies
ectotherms, often abundant, conspicuous, easy to locate, observe and capture
Insectivorous, eat prey whole (not "warm fuzzies")
Ectothermy facilitates metabolic inactivity, Confers an advantage over birds
(one day's food supply for a bird lasts same-sized lizard a month)
Diverse, 4 major lineages (iguania, scleroglossa, autarchoglossa, anguimorpha)

Habitats

Creeks, rivers, swamps, ponds, lakes, oceans (turtles, frogs, snakes, crocs)
Forests (deciduous, rainforest), savannas, grasslands, thornscrub, shrubby habitats
Deserts (warm, cold)
Sandridges, sandplains
Rocky outcrops ("tors," "kopjes")
Habitat specificity [shrub-Acacia, sandplain, sandridges (flat, base, slope, crest)]
Habitat niche breadth (reciprocal of Simpson's 1949 diversity index)

Habits
Aquatic (both freshwater and marine)
Arboreal, semiarboreal, climbing ground feeders
Terrestrial (open, closed)
Saxicolous
Fossorial (subterranean)

Microhabitats (sun, shade)
On ground, in open, near grass, near bush, under tree, other
Above ground, low or high
Structural niche (perch height and diameter, Anolis)
Below ground
Diurnal versus nocturnal retreats
Microhabitat niche breadth (reciprocal of Simpson's 1949 diversity index)
Anatomical correlates of ecology (tail length, limb length, jaw length, etc.)

Daily and Seasonal Patterns of Activity
Anuran breeding seasons
Daily march of temperature, windows of opportunity
Unimodal & bimodal periods of activity
Diurnal-Nocturnal (also crepuscular)
Does temporal separation reduce dietary overlap (competition)?

Thermoregulation
Cowles and Bogert (1944) classic paper
Ectotherms versus endotherms
Poikilotherms versus homeotherms
Homiostaesis (regulation never perfect)
Schultheiss thin-bulb rapid reading cloacal thermometers (Heath's beer cans)
Thermoconformer --> thermoregulator continuum (slope BT versus AT)
Arboreal vs. terrestrial desert lizards (% microhabitats in sun vs. time of day)
Behavioral thermoregulation

Color, Background Matching

Norris (1967)
1) Middle activity-level color match (Callisaurus, Dipsosaurus)
2) Upper activity-level color match (Uma)
3) Pseudomatch, dazzle effect (blinding light saturates human eye), very reflective substratum (white sand, Holbrookia)
4) Color match, no lability (Pisgah Lava Uta)

Modern Day Thermoregulation Studies

"Set points," temperatures at which heat seeking and heat avoidance occur
"Null" lizards (randomly-placed copper models)


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Last updated 17 Feb 1997 by Eric Pianka