•How does chromosomal
rearrangement result in
morphological and behavioral differences?
• For
reasons discussed at the meeting, structural rearrangements of chromosomes can result in complex and pervasive changes
in the activity of many genes
and gene products. The specific changes
that occur in White-throated
Sparrows are not known.
•Why do birds choose
mates of the opposite morph?
• Although
many hypotheses have been advanced, the answer to this question is not known with any certainty. However, the answer may lie in behavioral
factors which make same-morph
matings incompatible. White-striped
birds are very aggressive
and fight between themselves, possibly making WS x WS pairings unstable.
Tan-striped birds exhibit reduced territorial behavior, and TS x TS pairs have difficulty keeping possession of a
territory; this would weaken the pair bond.
Occasionally, however, both of these pairings do occur, and they succeed in fledging young.