Evolutionary genetics and plant reproductive biology.
My research seeks to understand fundamental processes in plant reproduction and evolution using genetics and genomics. Current research is focused on studying the interacting forces of mating system, interspecific hybridization, and polyploidy in the evolution of taxonomically ‘difficult’ genera, in particular Senecio (ragworts, Asteraceae) and Sorbus (whitebeams, rowans and wild service trees, Rosaceae).
The genomic basis of adaptation and speciation in the genus Senecio (Asteraceae)
Speciation events in Senecio have occurred relatively recently and involve examples of ecological speciation (sister species Senecio aethnensis and S. chrysanthemifolius) and hybrid speciation, both homoploid (S. squalidus) and allopolyploid (S. cambrensis). This project seeks to understand the genomic basis of speciation in the closely related species S. aethnensis and S. chrysanthemifolius, which diverged on Mt Etna, Sicily ~300 thousand years ago, and their homoploid hybrid, S. squalidus (Oxford ragwort), which evolved in allopatry in the UK following its introduction via the Oxford Botanic Garden ~300 years ago. The project is in collaboration with Dmitry Filatov (Oxford), Tom Batstone and Gary Barker (Bristol), Richard Abbott (St Andrews), Adrian Brennan (Durham) and Matthew Hegarty (IBERS, Aberystwyth). Current work is focused on analysing draft genome sequences, transcriptomes, and microRNA profiles for all three Senecio species to determine the relative importance of coding sequence changes vs non-coding regulatory sequence changes in their genetic divergence and adaptation to their distinct habitats.
The molecular basis of sporophytic self-incompatibility (SSI) in the Asteraceae
Another aspect of the Senecio genome project involves bioinformatic analysis of a genomic region containing candidate genes for self-incompatibility - the S-locus. The identification of a putative S-locus in Senecio (in collaboration with Tom Batstone, Bristol), and in Cichorium (chicory, in collaboration with Theo Hendriks and Marie-Christine Quillet) offers an opportunity to elucidate the molecular basis of SI in the Asteraceae.
Genetic divergence, mating systems, and ongoing evolution in the genus Sorbus (Rosaceae)
This project uses molecular markers (cpDNA, microsatellites and dd-RAD) to understand the evolutionary relationships between UK and European Sorbus species. Work to date has shown that Sorbus diversification in the Avon Gorge, Bristol is ongoing and is driven by hybridization, polyploidy, and facultative apomixis. These findings have influenced conservation management strategy for Sorbus in the Avon Gorge – a world ‘hotspot’ for Sorbus diversity. Current research in collaboration with Mike Fay (RBG Kew) seeks to determine the origin of Sorbus porrigentiformis, which has been central to the origin of new Sorbus taxa in the UK via hybridization.
Brennan AC, Hiscock SJ, Abbott RJ (2014) Interspecific crossing and genetic mapping reveal intrinsic genomic incompatibility between two Senecio species that form a hybrid zone on Mount Etna, Sicily. Heredity 113: 195-204.
Taylor RS, Tarver JE, Hiscock SJ, Donoghue PCJ (2014) Evolutionary history of plant microRNAs. Trends in Plant Sciences. 19: 175–182.
Brennan AC, Harris SA, Hiscock SJ (2013) The population genetics of sporophytic self-incompatibility in three hybridizing Senecio (Asteraceae) species with contrasting population histories. Evolution 67: 1347-1367.
Chapman MA, Hiscock SJ, Filatov DA (2013) Genomic divergence during speciation driven by adaptation to altitude. Molecular Biology and Evolution 30: 2553-256.
Ludwig S, Robertson A, Rich TCG, Djordjevic M, Cerovic R, Houston L, Harris SA, Hiscock SJ (2013) Breeding systems, hybridization and continuing evolution in Avon Gorge Sorbus. Annals of Botany 111: 563-575.
Osborne, OG, Batstone TE, Hiscock SJ, Filatov DA (2013) Rapid speciation with gene flow following the formation of Mt Etna. Genome Biology and Evolution 5: 1704-1715
Brennan AC, Barker D, Hiscock SJ, Abbott RJ. (2012) Molecular genetic and quantitative trait divergence associated with recent hybrid speciation: a study of Senecio squalidus (Asteraceae). Heredity 108: 87-95.
Allen AM, Thorogood CJ, Hegarty MJ, Lexer C, Hiscock SJ (2011) Pollen-pistil interactions and self-incompatibility in the Asteraceae: new insights from studies of Senecio squalidus L. (Oxford ragwort). Annals of Botany 108: 687-698.
Hegarty, MJ, Batstone T, Barker, GLA, Edwards, KJ, Abbott, RJ, Hiscock, SJ. (2011) Non-additive changes to cytosine methylation as a consequence of hybridization and genome duplication in Senecio (Asteraceae) Molecular Ecology 20: 105-113.
Allen AM, Lexer C, Hiscock SJ. (2010) Comparative analysis of pistil transcriptomes reveals conserved and novel genes expressed in dry, wet, and semidry stigmas. Plant Physiology 154: 1347-1360.
Brennan AC, Hiscock SJ. (2010) Expression and inheritance of sporophytic self-incompatibility in synthetic allohexaploid Senecio cambrensis (Asteraceae). New Phytologist 186: SI, 251-261.
Robertson A, Rich TCG, Allen AM, Houston L, Roberts C, Bridle JR, Harris SA, Hiscock SJ. (2010) Hybridization and polyploidy as drivers of continuing evolution and speciation in Sorbus. Molecular Ecology 19: 1675-1690.
Hegarty, MJ, Barker, GLA, Brennan, AC, Edwards, KJ, Abbott, RJ, Hiscock, SJ. (2009) Extreme changes to gene expression associated with homoploid hybrid speciation. Molecular Ecology 18: 877 - 889.
Thorogood CJ, Rumsey FJ, Harris SA, Hiscock SJ (2008) Host-driven divergence in the parasitic plant Orobanche minor Sm. (Orobanchaceae). Molecular Ecology 17: 4289-4303.
Hiscock SJ, Allen A. (2008) Diverse cell signalling pathways regulate pollen-stigma interactions: the search for consensus. Tansley Review New Phytologist 179:286-317.
Hegarty MJ, Hiscock SJ. (2008) Genomic clues to the evolutionary success of polyploid plants. Current Biology 18: R435-R444.
Hegarty M, Hiscock, SJ. (2007) Polyploidy: Doubling up for Evolutionary Success. Current Biology 17: R927-R929.
McInnis, SM, Desikan, R, Hancock, JT, Hiscock, SJ. (2006) Production of reactive oxygen species and reactive nitrogen species by angiosperm stigmas and pollen: potential signalling crosstalk. New Phytologist 172: 221-228.
Hegarty, MJ, Barker, GL, Wilson, ID, Abbott, RJ, Edwards, KJ, Hiscock, SJ. (2006) Transcriptome shock after interspecific hybridization in Senecio is ameliorated by genome duplication. Current Biology 16: 1652-1659.
Hegarty, MJ, Hiscock, SJ. (2004) Hybrid speciation in plants: new insights from molecular studies. New Phytologist 165: 411-423