Evolution and Development of Butterfly Wing Patterns
- the eyespots of Bicyclus anynana
During my Ph.D. work at the University of Leiden (The Netherlands),
Paul Brakefield and myself used Bicyclus anynana
to explore different (populational and organismal, evolutionary and developmental)
processes that shape variation in morphology.
Using artificial selection on a large laboratory population,
we explored the possibilities for changes in dorsal forewing eyespot size.
Despite the evidence that all eyespots are genetically and developmentally
coupled, artificial selection based on a single lab population produced
changes in the
two target eyespots in
and matched variation found
across different Bicyclus species
These results revealed much flexibility for
independent changes in individual eyespots, probably resulting from the
balance between the origin of all eyespots as a single developmental module
and a history
of selection favouring eyespot individuality
Despite such flexibility, further
illustrated by the phenotypes produced by different
spontaneous mutations of large effect,
there are obvious genetic correlations across eyespots on the same butterfly
The phenotypically divergent lines derived by selection were used in a number
of experiments aiming at understanding the mechanisms underlying the production
and maintenance of variation in eyespot size.
These included laboratory mate choice experiments testing whether female B. anynana
showed preference for males with different eyespot sizes, and manipulative experiments
on pupae analyzing the changes in the
cellular interactions underlying eyespot formation
The selection lines were also used to study the molecular genetic basis of variation in
B. anynana eyespot size. This work was done in collaboration with
Tony Long at the
University of California at Irvine (CA, USA).
Developmental biologists identified a number of
genetic pathways involved in eyespot formation but little was known about which genes
(if any) within the implicated pathways contributed to variation in eyespot patterns.
We focused on the transcription factor
Distal-less and showed that different alleles at this locus co-segregate
with eyespot size in laboratory crosses between butterflies from different artificial
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