Ten species in one: DNA barcoding reveals cryptic species in the neotropical skipper butterfly Astraptes Fulgerator Paul Hebert, Erin Penton, John Burns, Daniel Janzen & Winnie Hallwachs Proceedings of the National Academy of Sciences 2004 Content: Jan Critique: Emily In

DNA Barcoding What is it? ● Large scale screening of just a few reference genes for species ‘barcodes’. e.g. COI (Cytochrome C Oxidase 1) mtDNA Two purposes : 1)Molecular classification of unknown individuals to identified taxa. (e.g. the field barcoder) 2) Discovery of previously unknown species. (e.g. cryptic species)

DNA Barcoding Is it anything really new? ………NO ………. BUT! Scale & Standardization ‘One gene fits all’

DNA Barcoding However, ‘Barcoding’ is a bit of a misnomer… … not all individuals have the same ‘barcode’! Thus required that: Intraspecific variation << Interspecific variation

DNA Barcoding For example in moths and birds it has been shown that: - Intraspecific sequence variation < 0.5%. - Interspecific sequence variation > 5%. Thus the general rule that > 3% sequence divergence is indicative of separate species. Recognised sister taxa generally show > 3% sequence divergence.

Study Species Described in 1775 Single Species Common USA to Argentina Near desert to rainforest Neotropical Skipper Butterfly Astraptes fulgerator

Study Species However… Diversity of Food Plants Caterpillar Color Pattern V. subtle differences in adult morphology. 6 – 7 Species??? Years more work…

But wait…… ‘DNA barcoding’ is here!

Methods 484 museum specimens. Data on food plant, caterpillar color pattern & adult morphology. ‘legs away for DNA’ Barcoding at Guelph: –Extraction –Amplification of 648bp COI region –Sequencing

Methods Sequences aligned. Divergence measured with K-2-P distance model. Displayed in neighbour joining tree.

Results 10 Distinct Sequence Groups Close correspondence with other characteristics

Key Points Branch lengths Other characters Intraspecific v Interspecific

TRIGO & CELT > 3% Sequence Divergence Diverged ~ 2 & 4 mya Unique food plants Distinct Spp?

FABOV, HIHAMP & INGCUP < 0.5% Sequence Divergence Diverged < 0.5 mya Host plants not exclusive ???Distinct Spp???

Conclusion Not one species BUT….. A complex of 10 cryptic species!

Conclusion How many more such complexes are out there? Crucial to our estimates of global biodiversity and extinction rates. DNA barcoding could provide the answers.

Conclusion Isn’t DNA Barcoding great?

Recorded debate on DNA Barcoding at: