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SUMMARY:Unlocking the evolutionary secrets of a key innovation in the worl
 d’s most variable daisy inflorescence\, Gorteria diffusa - Joshua Kestel
 \, University of Cambridge (Department of Plant Sciences)
DTSTART:20260305T130000Z
DTEND:20260305T140000Z
UID:TALK240235@talks.cam.ac.uk
CONTACT:131500
DESCRIPTION:Adaptive radiation\, the diversification of species from a com
 mon ancestor into ecologically distinct forms\, can occur following the ev
 olution of key innovations. Such innovations require sufficient genetic va
 riation\, yet only a subset of emerging traits will ultimately contribute 
 to diversification. In plants\, sexual deception\, in which flowers mimic 
 female insects to attract male pollinators that attempt pseudocopulation\,
  is considered a potential key innovation. However\, few sexually deceptiv
 e systems include multiple co-occurring phenotypes\, limiting our ability 
 to link insect-mediated gene flow with underlying genetic modules and thei
 r phenotypic consequences. Gorteria diffusa\, a South African daisy\, is u
 nusual in possessing a spectrum of sexually deceptive morphotypes. Over th
 e past approximately 1.5 million years\, the species has radiated into 16 
 morphotypes\, several of which hybridise in narrow secondary contact zones
 . This diversification is hypothesised to stem from the evolution of sexua
 lly deceptive petal spots that mimic female Megapalpus capensis bee flies\
 , although this remains an ongoing area of research. To address this\, we:
  1) sampled 500 G. diffusa individuals across four hybrid zones with varyi
 ng levels of sexual deception in 2018\; 2) conducted manual pollinator obs
 ervations in 24 Gorteria populations in 2025\; and 3) collected 280 M. cap
 ensis pollen loads in 2025 to examine M. capensis foraging patterns. Our G
 enotyping-by-Sequencing data identified six genomic clusters with hybrids 
 occurring predominantly within these clusters. Admixture was strongest in 
 central regions of the hybrid zones\, and cline shapes varied\, with the s
 teepest between strongly deceptive and moderately or weakly deceptive morp
 hotypes. Megapalpus visits in 2025 were low\, 0.019 ± 0.0025 SE flies per
  flower\, equivalent to one fly per 53 flowers. Megapalpus visited approxi
 mately eight species per 750 m2 and was 2.3 times more likely to forage on
  G. diffusa than on other Asteraceae\, although deceptive and non-deceptiv
 e morphs received similar visit rates. Together\, these results suggest th
 at adaptive radiation in G. diffusa reflects complex interactions among ge
 netic structure\, pollinator behaviour\, and both pre-zygotic and post-zyg
 otic barriers\, contributing to novel phenotypes and potential key innovat
 ions.
LOCATION:Part II Lecture Theatre\, Department of Zoology
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