Two in one: cryptic species discovered in biological control agent populations using molecular data and crossbreeding experiments

Iain D Paterson; Rosie Mangan; Douglas A Downie; Julie A Coetzee; Martin P Hill; Ashley M Burke; Paul O Downey; Thomas J Henry; Stephe G Compton

doi:10.1002/ece3.2297

Two in one: cryptic species discovered in biological control agent populations using molecular data and crossbreeding experiments

Ecol Evol. 2016 Jul 30;6(17):6139-50. doi: 10.1002/ece3.2297. eCollection 2016 Sep.

Authors

Iain D Paterson¹, Rosie Mangan¹, Douglas A Downie¹, Julie A Coetzee¹, Martin P Hill¹, Ashley M Burke¹, Paul O Downey², Thomas J Henry³, Stephe G Compton¹

Affiliations

¹ Department of Zoology and Entomology Rhodes University PO Box 94 Grahamstown 6140 South Africa.
² Department of Zoology and Entomology Rhodes University PO Box 94 Grahamstown 6140 South Africa; Institute for Applied Ecology University of Canberra Canberra Australian Capital Territory 2601 Australia.
³ Systematic Entomology Laboratory ARS, USDA, c/o National Museum of Natural History Smithsonian Institution Washington District of Columbia 20013.

Abstract

There are many examples of cryptic species that have been identified through DNA-barcoding or other genetic techniques. There are, however, very few confirmations of cryptic species being reproductively isolated. This study presents one of the few cases of cryptic species that has been confirmed to be reproductively isolated and therefore true species according to the biological species concept. The cryptic species are of special interest because they were discovered within biological control agent populations. Two geographically isolated populations of Eccritotarsus catarinensis (Carvalho) [Hemiptera: Miridae], a biological control agent for the invasive aquatic macrophyte, water hyacinth, Eichhornia crassipes (Mart.) Solms [Pontederiaceae], in South Africa, were sampled from the native range of the species in South America. Morphological characteristics indicated that both populations were the same species according to the current taxonomy, but subsequent DNA analysis and breeding experiments revealed that the two populations are reproductively isolated. Crossbreeding experiments resulted in very few hybrid offspring when individuals were forced to interbreed with individuals of the other population, and no hybrid offspring were recorded when a choice of mate from either population was offered. The data indicate that the two populations are cryptic species that are reproductively incompatible. Subtle but reliable diagnostic characteristics were then identified to distinguish between the two species which would have been considered intraspecific variation without the data from the genetics and interbreeding experiments. These findings suggest that all consignments of biological control agents from allopatric populations should be screened for cryptic species using genetic techniques and that the importation of multiple consignments of the same species for biological control should be conducted with caution.

Keywords: Biological species concept; C01; DNA‐barcoding; Eccritotarsus catarinensis; Eichhornia crassipes; Inter Simple Sequence Repeats; reproductive incompatibility.