Navy blue. For other uses, see Navy blue (disambiguation). Navy blue is a very dark shade of the color blue. French sailor in dark blue uniform. Navy blue got its name from the dark blue (contrasted with white) worn by officers in the British Royal Navy since 1748 and subsequently adopted by other navies around the world.
Hybrid sterility is what results when individuals from two. different species are able to mate but their offspring is infertile, meaning that their. offspring are not able to reproduce. Because this occurs after the formation of the. zygote, this is a postzygotic isolating mechanism, not a prezygotic mechanism.
Five reproductive barriers are habitat isolation, temporal isolation, gametic isolation, hybrid breakdown, and reduced hybrid fertility. Habitat isolation, temporal isolatâ¦ion, and gametic isolation are examples of prezygotic reproductive barriers, meaning that they impede mating or hinder fertilization if mating does occur.