Natural hybridization in heliconiine butterflies: the species boundary as a continuum

Table 1 Natural and laboratory hybridization between species of Heliconius (see Additional File 1 for specimen details)

Genus	Species 1	Species 2	Geographic relationship	No. of natural hybrids	Backcrossing in lab or field	Laboratory hybrids	Molecular evidence	Assortative mating	F₁ female sterility
Eueides
	lybia	vibilia	sympatric	1	-	-	-	(+)	?
	isabella	vibilia	sympatric	4	-	-	-	(+)	?
	isabella	procula	sympatric	1	-	-	-	(+)	?
	pavana	vibilia	sympatric	1	-	-	-	(+)	?
Heliconius (melpomene-cydno-silvaniform group)
	numata	melpomene	sympatric	4	-	-	-	(+)	?
	ismenius	cydno	sympatric	-	+	+	-	+	+
	hecale	melpomene	sympatric	2	-	+	-	+	?
	hecale	elevatus	sympatric	3	+	-	-	(+)	?
	hecale	atthis	sympatric	-	+	+	-	+	+
	ethilla	melpomene	sympatric	4	+	-	-	+	?
	ethilla	numata	sympatric	2	-	-	-	(+)	?
	ethilla	besckei	sympatric	6	+	-	-	(+)	?
	melpomene	cydno	sympatric	68	+	+	+	+	+
	melpomene	heurippa	sympatric	1	+	+	+	+	+
	melpomene	pachinus	sympatric	-	+	+	+	+	+
	cydno	pachinus	parapatric	3	+	+	+	+	-
	cydno	heurippa	parapatric	-	+	+	+	+	-
Heliconius (erato-sara-sapho group)
	himera	erato	parapatric	57	+	+	+	+	-
	erato	charithonia	sympatric	1	-	-	-	+	?
	charithonia	peruvianus	parapatric	1	+	-	+	(+)	?
	hecalesia	hortense	sympatric	1	-	-	-	(+)	?
	hecalesia	clysonymus	sympatric	1	-	-	-	(+)	?
Total				161

ISSN: 2730-7182