AFUW-ACT
Inc. Meeting Report
Topic: BEHAVIOUR OF LIZARDS
Speaker: Dr Sharon Downes
In 1758 Carl Linnaeus said lizards were 'Foul and Loathsome creatures'.
In fact they have many interesting behaviours. I shall tell three stories
to show their phenotypic plasticity in response to environmental heterogeneity.
1. LOCAL SKINKS Eggs were collected and taken to the University where
bush temperatures were simulated for their hatching. It was found that
skinks incubated under hot conditions were bigger and ran fastest. There
were also differences in gender - females under hot conditions were
heavier than the males. If eggs were laid in hot areas there were more
females than males; if in a colder area there were more males.
2. JACOBSON'S ORGAN is for flicking the tongue out. This can determine
chemicals if lizard is exposed to danger. For example geckos are preyed
on by specific snakes- broad headed, which are dangerous. Small eyed
snakes do not eat geckos. It was found that geckos responded strongly
to chemical cues from broad headed snakes. Anti - predator behaviour
- lie flat on rock so are hard to see and flick their tails and can
detach their tails to distract attention. Foraging behaviour - Broad
headed snakes remain within a specific area. In experiments in the lab.,
when sedentary and active movement of snakes was mimicked, it was found
that geckos preferred sites without snakes or ones where snake was sedentary.
3.SWEDEN - GOTTENBURG - Work was done in Sweden on sun bathing lizards
on rocks. The female sand lizard was drab brown throughout and the male
was spectacular green display under throat and stomach during the mating
season. In a contest between competing males it was found that the larger
male mates with the female. Survival relates to the intelligence of
lizards. By observing behaviour it was noted which male mated with which
female and the eggs were collected; DNA fingerprinting of offspring
showed that the male most closely related to the female sired very few
offspring, and the male least closely related to the female selected
sperm to allow greatest chance of survival.
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