I need more details to answer your question
He observed 15 different finch species that originated as one ancestral bird. all differing in body shape, beak size, and mating habbits
I would say "gene", as it is the basic unit of heredity.<span />
<h2>Vasa recta </h2>
Explanation:
The vasa recta is a specialized capillary that branches from the efferent arteriole; The blood flow in the vasa recta runs parallel, but in the opposite direction to the flow of tubular filtrate within the nephron loop
- The vasa recta capillaries are long, hairpin-shaped blood vessels that run parallel to the loops of Henle
- The hairpin turns slow the rate of blood flow, which helps maintain the osmotic gradient required for water reabsorption
- Absorbed water is returned to the circulatory system via the vasa recta, which surrounds the tips of the loops of Henle
- Because the blood flow through these capillaries is very slow, any solutes that are reabsorbed into the bloodstream have time to diffuse back into the interstitial fluid, which maintains the solute concentration gradient in the medulla; this passive process is known as counter-current exchange
