The diversity of life on our planet is generated by the process of speciation, the splitting of a population into two divergent groups that can coexist in a state of nature. What changes at the genomic level cause speciation are still obscure. This is a time to jettison preconceived ideas, and to absorb what new data can tell us.
Today, these data will frequently include whole genome sequences. Heliconius
melpomene is the first butterfly species to have had its genome both sequenced
and mapped to chromosomes...
Heliconius are famous for the extraordinary diversity of colour patterns
within and between species. All of the heliconiine and ithomiine species
are distasteful to predators, and their bright "aposematic"
coloration is used to warn enemies. I have long been interested in mimicry,
and newer genomics work is at last leading to an understanding of the
regulatory genetic switches involved in mimicry. ...
Many species hybridize with other species, and this can lead to wholesale
transfer of variation important in adaptive evolution. In some cases, this
sudden acquisition of recombined adaptive traits can lead to the origins
of new species, or "hybrid speciation." Our group, working with Heliconius, ithomiines,
and other insects, has been at the forefront of this recent research. ...
The newer understanding we have reached about the genomic nature of species
and hybridization is leading to a re-examination of what we mean by the
term "species." For instance, the argument that species are "reproductively
isolated" seems to lose its power when over 40% of the genome has undergone
admixture between the sympatric pair Heliconius cydno and Heliconius melpomene. ...
Interest in hybridization and revised species concepts led to a fascination
with why others had held different views in the past ...