Management Notes

Reference Notes for Management

Research on flat-tailed horned lizards demonstrated that natural selection favored lizards that:

Research on flat-tailed horned lizards demonstrated that natural selection favored lizards that:


A. ran faster when exposed to bright sunlight
B. buried themselves faster when startled
C. searched for ants hidden under logs
D. had longer horns on the rear of the skull

The Correct Answer Is:

D. had longer horns on the rear of the skull

Correct Answer Explanation: D. had longer horns on the rear of the skull

The research on flat-tailed horned lizards has provided valuable insights into the mechanisms of natural selection and the adaptations of this species to its environment. The correct answer to the question is option D: “had longer horns on the rear of the skull.”

The longer horns on the rear of the skull in flat-tailed horned lizards serve as a key adaptation that has been favored by natural selection. These elongated structures, known as occipital horns, play a crucial role in the lizard’s defense against predators.

When threatened, the lizard adopts a defensive posture by flattening its body and burying its head into the ground, leaving the horns prominently displayed. This serves as a deterrent to predators, making the lizard appear larger and more challenging to attack.

The elongated occipital horns are not only visually imposing, but they also provide a physical barrier that further deters predators. The horns are sharp and pointed, making it difficult for predators to grasp the lizard’s head or swallow it whole.

This defense mechanism greatly enhances the lizard’s chances of survival in the face of potential threats.

Furthermore, the longer occipital horns also play a role in intraspecific competition, particularly during territorial disputes or mating interactions. Lizards with longer horns are more likely to establish dominance over others, which can increase their reproductive success and overall fitness.

Now, let’s discuss why the other options are not correct:

A. Ran faster when exposed to bright sunlight:

While speed can be advantageous in certain ecological contexts, it is not the primary selective pressure acting on flat-tailed horned lizards. In their native arid environments, speed may be less critical for survival compared to other traits.

These lizards have evolved a suite of adaptations that are better suited to their specific ecological niche. For instance, their flattened bodies and cryptic coloration are more geared towards camouflage and minimizing detection, rather than relying solely on speed to escape predators.

Furthermore, flat-tailed horned lizards are ectothermic, meaning they rely on external sources of heat to regulate their body temperature. They are most active during periods of optimal temperature and often seek shelter during extreme conditions.

This reliance on environmental factors for thermoregulation suggests that their evolutionary success is more closely tied to their ability to utilize the available resources and adapt to the challenges of their particular habitat.

B. Buried themselves faster when startled:

The ability to quickly bury themselves is indeed an important defense mechanism for flat-tailed horned lizards. When threatened, they will often flatten themselves against the ground and use their limbs to rapidly dig into loose soil or sand.

However, while this behavior is crucial for evading immediate danger, it does not represent the primary trait that has been favored by natural selection in this species.

In fact, many lizard species possess similar burrowing abilities, as it is a widespread survival strategy in response to predators. Therefore, while burying behavior is an important aspect of their defensive repertoire, it is not the specific trait that has been demonstrated to undergo strong selective pressures leading to evolutionary changes.

C. Searched for ants hidden under logs:

This option pertains to the lizard’s feeding behavior. While diet and foraging strategies are indeed relevant to a species’ overall ecological niche, they are not the primary drivers behind the observed preference for longer occipital horns in flat-tailed horned lizards.

Their dietary preferences and foraging tactics are likely influenced by the availability of specific prey items in their environment, but this does not account for the evolutionary significance of occipital horns.

Additionally, while ants are a common prey item for flat-tailed horned lizards, this aspect of their behavior is more reflective of their ecological role as insectivores rather than a key factor in the selective pressures shaping their adaptations.

In summary, the research on flat-tailed horned lizards underscores the importance of understanding the specific ecological pressures and adaptations that shape a species’ evolutionary trajectory.

While traits such as speed, burrowing behavior, and feeding strategies are all relevant to their overall ecology, it is the longer occipital horns that have been demonstrated to be favored by natural selection in this particular species.

These adaptations enhance their survival and reproductive success in their arid habitat, showcasing the intricate interplay between selective pressures and the evolution of specialized traits.

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