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What can we learn from evo-devo on butterfly wing patterns?
major contributions today:
Patrícia Beldade
Hans Roskam
Suzanne Saenko
Henri Descimon
David Lees
Bas Zwaan
our Lab. and others:
AD Long, A Monteiro,
D Stern, V French
Funding: LU, N.W.O.,
HFSP, NSF, JGI
also, Animal & Plant Sciences, University of Sheffield, UK
Evo-Devo:
How do developmental
processes evolve?
(how do eyespots evolve
via gene redeployment?)
How does development
contribute to shaping
evolution?
(are patterns of eyespot
diversity influenced by
how they are formed?)
S Saenko
Development: toolkit of signalling processes and pathways
Adaptation: by generating phenotypic variation for natural
selection to sieve. Does how development works bias this
process and thus become reflected in patterns of evolution?
genomics
resources
mapping G to P
evo-devo
natural
selection
Know some of how Natural Selection works – mimicry case studies.
evo-devo is coming to these as well
Wing
Patterns
But influenced by
development too?
Species of
Delias
captured by
T. Larsen at a
single site
over 1 h
in Borneo
Are there patterns
that do not occur
due to how development works?
Presumably
natural selection
with eyespots:
handle on devo
Eyespot Pattern Evolution using
evo-devo to link process and pattern.
First an evolutionary scenario:
ELABORATION
ORIGIN?
TINKERING
and
radiation – is
everything
possible?
Gene co-option
and redeployment
Bicyclus and related genera
Bicyclus anynana – the lab ‘rat’ butterfly and eyespot evo-devo
Artificial selection is major tool
Eyespots formed around signalling cells: Transplanted Bicyclus
organizer or focus gives an ectopic
++
Model of signal source
or inductive organizer
Skills of Vernon French
Evo-devo
Tool kit of
signalling
pathways
with redeployment
in new:
tissues;
times and
functions
Genes: here
expression
patterns of
Distal-less
in developing
wings;
hedgehog
signalling
pathway;
also Notch
(Reed & Serfas
2004)
with Sean
Carroll & team
Goldeneye x Bigeye mating
Mutant
Goldeneye
has changed
expression of
engrailed and
spalt in pupae,
in response to
focal signalling
Brunetti et al. 2001 Curr Biol
Some Bicyclus mutants illustrate pathway redeployment
Eyespot - number
- shape
wing
pigmentation
- size
wild type
- colour
5 mutants
here are
homozygous
lethal
Wild type
Bigeye
Spread size
Spread
Frodo
Spread colour
Suzanne Saenko
Pathways recruited to make eyespots also function in
embryonic development - e.g. here the segment
polarity gene, engrailed, at 12h and 20h (of 4d)
Potential route to identifying genes
Work of Suzanne Saenko
Spread mutation may shed more light on the eyespot colour
determination? (Suzanne Saenko with thanks to M. Akam/N. Patel)
embryo
wing
WT
Engrailed is
anterior in
each segment
Engrailed
- Recessive lethal (embryos)
- Changed eyespots in heterozygote adults
(homozygous)
Engrailed both post- and
anterior in each segment
Spread
(heterozygous)
Phenotype similarity with a
Drosophila mutant:
shaggy/GSK-3
Are there QTL at such loci that are evolutionarily relevant?
A key component of
the Wnt pathway
? Hedgehog/Wnt
interactions have been
redeployed too
Why use eyespots to analyse whether development matters?
Bigeye
++
Pattern is a Module of repeated
elements with a shared development
Also,
a common
genetics
So how do eyespots become different to
each other for a) size and b) colour?
Black
Gold
Patrícia Beldade
Artificial selection along two axes
Selection responses for FW eyespot relative size
Representative phenotypes after 11 and 25 generations
High flexibility and divergence; highly novel phenotypes
Beldade et al., Nature or PNAS 2002a, b; 2003
Is this flexibility reflected within the genus and the lineage
taenias
procorus
danckelmani
Some
Bicyclus
species
Photos:
smithi
simulacris
nobilis
Hans
Roskam
Variation in another highly speciose, Asian genus
Mycalesis
species
sirius
splendens
mucia
Photos:
Hans
Roskam
medus
mineus
oculus
Plot the selected line wings and the species means in morphospace
So, the genera together indicate no constraints on size with perhaps only
a weak effect of any axis of least resistance (Am Nat, 2006);
Why the difference across genera? We don’t know: courtship differs??
II, What about eyespot colour composition?
‘Black’
selected
line
‘Gold’
Monteiro et al 1997, Genetics
Original experimental concept - now targeting the hindwing pattern
Cerisse
Allen
4
6
Selection responses for HW eyespot colour composition – no
novel phenotypes being produced along the ‘uncoupled axis’
at gen 11
Allen et al, in press, BMC Evol Biol
Is this reflected in consequences for eyespot colour diversity in lineage?
Bicyclus species
YES: narrow OR broad rings
Mycalesis species
V. French
Models for
eyespot size
and colour
based on
grafting
experiments:
Size depends
on local sources
of signal while
Colour depends
on threshold
responses across
whole wings and is
inflexible
Follows on
Monteiro
et al 1997;
Beldade 2002
So Development
can matter
And contribute
to biodiversity
But maybe there is more than one way to make an eyespot and
this can break any fundamental constraint (S Saenko and P Beldade)
Parnassius apollo
(with Henri Descimon)
Heteropsis iboina
(with David Lees, BMNH and B. Kubbinga)
Here eyespots have a startling function and
flicking display – novel function & ecology
b) deeper in the butterfly phylogeny?
Apollo ‘Papilioniid’ butterflies,
Parnassius apollo
Eyespot-like markings also to
intimidate or startle predators
with Henri Descimon
mutant form: wiskotti
Distal-less (red) and Engrailed (green) expression in larval and
pupal wing discs; with thanks to Nipam Patel
P. apollo
hindwings
B. anynana
hindwings
No gene expression associated with patterning in apollo wings implies
co-option of colour band-patch pathways not nymphalid-type eyespots
First interspecific focal graft that has worked!; S, Saenko
control
B. anynana
focus grafted
into H. ibiona
An attractive notion is that here Heteropsis has produced a novel
pattern by combining two patterning systems;
If so, how did suite of patterning and behavioural traits evolve?
From B. anynana to genus-wide patterns in morphospace for satyrid butterflies
A broad Evo-Devo can begin to explore
patterns of evolution in morphospace,
And examine how the way development
works can contribute to shaping evolution
Flexibility
in eyespot
size
but not in
colour
??
Novelty
Elaboration and
Tinkering
Parallel
Evolution
Lake
Tanganyika
Lake
Malawi
‘only’
shaped by
natural
selection?
or ‘also’ by
developmental
bias;
by emergent
properties of
dev. system.
Kocher et al. 1993
Albertson & Kocher 2006
Much of theoretical morphospace is unoccupied, here for snail shells
– why: due to ecology & function, or also to how variation is generated?
Engrailed in wildtype (12 h) present only in posterior of each segment
S. Saenko
Engrailed in Spread homozygotes (12–14 h) also appears in anterior cells
Manipulative handles on development (after Fred Nijhout):
ablation or damage to central cells by piercing cuticle in early
pupae with a sharpened needle reduces or eliminates eyespots
control wing
treated