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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