Citation:
Rosser, N., Seixas, F., & Mallet, J. (2022). Sympatric speciation by allochrony? Molecular Ecology , 31, 3975-3978.
Abstract:
Sympatric speciation was once thought most improbable, but carefulstudy of some systems, particularly the apple maggot (Rhagoletis
pomonella) and related Rhagoletis species, has led to its reinstatement as
a likely mode of speciation in some cases. Different species and host
races in this clade of flies often have highly specialized host preference,
and along with frequent evolutionary shifts to different fruit species
between sister taxa, there is a likely effect of the timing of adult
emergence that follows host fruiting phenology. This is known as
"allochronic" isolation (from the Greek, meaning "different timing").
This overview covers recent discoveries by Inskeep et al. (Molecular Ecology, 2021) showing
how allochrony is a major factor in preventing gene flow between a pair
of sister species of Rhagoletis on different host fruits. Although the
authors do not claim to prove sympatric speciation, it does seem very
likely, and the work clearly underscores how readily host shifts via
allochrony can aid sympatric speciation.
Selection against melanism in UK after the Clean Air Act.