Final answer:
Species W and Y can likely be considered the same species, as they can produce fertile offspring, which fits the biological species concept. Genus B, with a wide variety of genetic traits, has a higher likelihood of surviving environmental changes. The ZW sex-determination system plays a crucial role in avian sex determination. The correct answer is option 4.
Step-by-step explanation:
When considering whether species W and Y are the same species, it seems that since they can produce fertile offspring, they may be considered the same species according to the biological species concept, which defines a species as a group of organisms that can breed and produce fertile offspring together in nature. This indicates that there is no complete reproductive barrier between species W and Y. However, the fact that species W cannot produce fertile offspring with species X or Z suggests that these species are reproductively isolated from species W and, therefore, distinct species.
Regarding the bird genera from your reference, genus B with a wide variety of genetic traits would have a higher probability of surviving after a volcanic explosion. This diversity increases the chances that some species within the genus will possess traits suitable for the new environmental conditions, a concept known as genetic diversity.
In the context of avian sex determination, it's interesting to note the use of the ZW sex-determination system, where the presence of different sex chromosomes (Z and W) determines if the bird will be male (ZZ) or female (ZW).