A) Explain why you might be more likely to find a large lizard foraging in the s

Question

A) Explain why you might be more likely to find a large lizard foraging in the shade, rather than a small lizard in the shade, or the large lizard in the sun.

B) If you found a dead lizard, what morphological cues could you use to infer its foraging strategy in life?

C) Because they are limbless, snakes must grab their prey using their heads. This is potentially risky for the snake, given the important things that can be found in the head. In what ways do snakes minimize the risk of damage to themselves while feeding?

D) Some species of lizards have temperature-dependent sex determination. What might be an adaptive reason for this, as opposed to just using genes?

E) Some anthropologists think that australopithecines were tool makers, not just users. What evidence leads them to believe this?

Explanation / Answer

A)

Reptiles use the environment to regulate their warmth. This strategy helps them conserve energy in the cold and rapidly ramp up their body temperature in the heat, but it also makes them particularly sensitive to global warming.

For most lizards, cooling down is as easy as moving into the shade or hiding under a rock, a research associate at the American Museum of Natural History in New York and a specialist in reptile biology. Reptiles warm up just as simply, by basking in the sun.

A lizard in a desert that feels like it needs to warm up for its metabolism to work better, it goes and sits on a rock in the sun. If it gets too warm from running around, it goes and sits under a rock in the shade.

Very big lizards like the Komodo dragon have so much mass that their bodies trap a lot of heat, allowing them to maintain a fairly consistent body temperature, almost like a mammal.

But for small lizards , maintaining this consistency is more difficult. Their bodies cool down and heat up when the air around them changes temperature even slightly. Small lizards can feel changes as subtle as the sun moving behind a cloud, and their metabolisms slow down to a level near that of hibernation when they rest in the shade. Then, when they move into the sunlight, the lizards become hyperactive.

B) Evolutionary changes in foraging style are often believed to require concurrent changes in a complex suite of morphological, physiological, behavioural and life-history traits. In lizards, species from families with a predominantly sit-and-wait foraging style tend to be more stocky and robust, with larger heads and mouths than species belonging to actively foraging families. Here, we test whether morphology and foraging behaviour show similar patterns of association within the family Lacertidae. We also examine the association of bite force abilities with morphology and foraging behaviour. Lacertid lizards exhibit considerable interspecific variation in foraging indices, and we found some evidence for a covariation between foraging style and body shape.

However, the observed relationships are not always in line with the predictions. Also, the significance of the relationships varies with the evolutionary model used. Our results challenge the idea that foraging style is evolutionarily conservative and invariably associated with particular morphologies. It appears that the flexibility of foraging mode and its morphological correlates varies among lizard taxa.

C) Snakes have no limbs or claws to overpower their prey. Some, like cobras and vipers, use venom to kill, while others, like checkered keelback water snakes, swallow frogs alive. But large snakes like pythons and boas need large meals. Swallowing kicking pigs and fighting deer alive would be impossible without getting grievously hurt in the struggle. The only weapon at their disposal is their muscular strength.

Pythons and boa constrictors strike and grab their prey. While six rows of sharp hooked teeth grip the animal firmly, the snake throws two or three loops of its muscular body coils around the victim’s torso like a straitjacket. The coils tighten until the poor animal becomes lifeless.

D) Temperature-dependent sex determination(TSD) is a type of environmental sex determination in which the temperatures experienced during embryonic/larvae development determine the sex of the offspring. It is only observed in reptiles and teleost. TSD differs from the chromosomal sex-determination systems common among vertebrates. It is the most popular and most studied type of environmental sex determination (ESD). Some other conditions, e.g. density, pH, and environmental background color, are also observed to alter sex ratio, which could be classified either as temperature-dependent sex determination or temperature-dependent sex differentiation, depending on the involved mechanisms.

As sex-determining mechanisms, TSD and GSD should be considered in an equivalent manner, which leads to reconsider the status of fish species that are claimed to have TSD when submitted to extreme temperatures instead of the temperature experienced during development in the wild since changes in sex ratio with temperature variation are ecologically and evolutionally relevant.

E) Archaeologists recognize four kinds of tools, 1) choppers, crude tools made by shearing one or a few pieces off a stone; 2) flake tools, implements made with numerous flakes, or small pieces chiseled off; 3) crude biface tools , ax-like tools or tools with a point made from stone, wood antler or bone that are fashioned by chipping way material from two or more sides; and 4) hand axes, which are similar to biface tools except they are made with more advanced skills. Sophisticated Acheulean hand axes are named after a French site. They were also produced in Africa and the Middle East

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