« Previous Abstract"Where one species leads, another follows: interspecies processions in tropical caterpillars"    Next AbstractVolatile Organic Compound Emissions from Prescribed Burning in Tallgrass Prairie Ecosystems »

Evolution

Title:		Pollinator specificity drives strong prepollination reproductive isolation in sympatric sexually deceptive orchids
Author(s):		Whitehead MR; Peakall R;
Address:		"Evolution, Ecology and Genetics, Research School of Biology, The Australian National University, Canberra, Acton 0200, Australia. michael.r.whitehead@gmail.com"
Journal Title:		Evolution
Year:		2014
Volume:		20140326
Issue:		6
Page Number:		1561 - 1575
DOI:		10.1111/evo.12382
ISSN/ISBN:		1558-5646 (Electronic) 0014-3820 (Linking)
Abstract:		"Few studies have quantified the full range of pre- and postzygotic barriers that limit introgression between closely related plant species. Here, we assess the strength of four isolating mechanisms operating between two morphologically similar and very closely related sympatric orchid taxa, Chiloglottis valida and C. aff. jeanesii. Each taxon sexually attracts its specific wasp pollinator via distinct floral volatile chemistry. Behavioral experiments with flowers and synthetic versions of their floral volatiles confirmed that very strong pollinator isolation is mediated by floral odor chemistry. However, artificially placing flowers of the two taxa in contact proximity revealed the potential for rare interspecific pollination. Although we found hybrid vigor in F1 hybrids produced by hand-crossing, genetic analysis at both nuclear and chloroplast loci showed significant and moderate-to-strong genetic differentiation between taxa. A Bayesian clustering method for the detection of introgression at nuclear loci failed to find any evidence for hybridization across 571 unique genotypes at one site of sympatry. Rather than inhibiting gene flow, postpollination barriers surveyed here show no contribution to overall reproductive isolation. This demonstrates the primacy of pollinators in maintaining species boundaries in these orchids, which display one of the strongest known examples of prepollination floral isolation"
Keywords:		"Animals Flowers/chemistry Genes, Chloroplast Genes, Plant Hybrid Vigor Hybridization, Genetic Oils, Volatile Orchidaceae/*genetics/physiology *Pollination *Reproductive Isolation *Sympatry Wasps/*physiology Chiloglottis floral isolation floral odor hybrid;"
Notes:		"MedlineWhitehead, Michael R Peakall, Rod eng Research Support, Non-U.S. Gov't 2014/02/18 Evolution. 2014 Jun; 68(6):1561-75. doi: 10.1111/evo.12382. Epub 2014 Mar 26"