Points of Agreement

Passage A
The striking black-and-white striping of zebras has puzzled evolutionary biologists since the days of Charles Darwin. While numerous hypotheses have been proposed over the decades—including camouflage against large predators, social cohesion within herds, and even individual identification—recent empirical evidence points most strongly toward thermoregulation as the primary evolutionary driver. In the scorching environments of the African savanna, a zebra's coat heats up unevenly under direct sunlight; the black stripes absorb significantly more heat than the adjacent white stripes. This stark temperature differential creates small-scale convection currents—often referred to as micro-eddies of air—just above the surface of the skin, effectively acting as an active cooling mechanism for the animal. Extensive field observations robustly demonstrate that zebras with the most pronounced, high-contrast striping are consistently found in the hottest regions of their geographic range, establishing a compelling correlation between coat pattern and environmental temperature gradients. It is undeniably true that controlled experiments have shown biting flies, such as tsetse flies and tabanids, struggle to land on striped surfaces due to optical illusions that disrupt their close-range visual processing. However, given the immense metabolic cost and lethality of severe heat stress in arid, open grasslands, it is highly probable that the fly-deterring property of stripes is merely a fortuitous secondary benefit. It remains an evolutionary byproduct of a trait selected fundamentally for keeping the animal physiologically cool under the relentless equatorial sun.

Passage B
Determining the true evolutionary purpose of zebra stripes requires meticulously analyzing the specific ecological pressures that most directly and severely impact equine survival and reproduction. Currently, the most scientifically compelling explanation centers squarely on protection from disease-carrying biting flies. Tsetse flies and tabanids (horseflies) are highly prevalent in typical zebra habitats and serve as vectors for fatal pathogens, including those causing equine infectious anemia and trypanosomiasis. Exhaustive field tests utilizing striped pelts and painted models have conclusively shown that these particular insects are severely visually confused by high-contrast striped patterns. Consequently, the flies tend to collide awkwardly with or completely avoid the striped surfaces instead of landing safely to feed. This profound reduction in bite rates undeniably offers a massive survival advantage. Proponents of alternative evolutionary theories frequently point to the potential thermal benefits of stripes, arguing that the temperature differences between heat-absorbing black hairs and reflective white hairs might generate cooling airflows over the zebra's body. However, rigorous thermographic imaging of zebras in their natural habitats has completely failed to demonstrate any significant reduction in core body temperature when compared to unstriped equids of similar size living in identical ecological conditions. While the striped coat itself may experience some localized surface cooling, this phenomenon does not translate to any meaningful systemic thermoregulation. The primary selective pressure for this distinctive morphology was undoubtedly the evasion of deadly parasitic flies, with any minor thermal effects being largely inconsequential to the animal's overall evolutionary fitness.

Based on the paired passages, which of the following statements represent points of agreement between the two authors? (Select all that apply)