My PhD

1. My Phd Project

The official title of my thesis was "The taxonomy of Senecio sect. Senecio: hybridisation and speciation". The aims were varied.

Initially the plan was to determine the ecological and genetic barriers to hybridization between Senecio aethnensis (picture) and S. chrysanthemifolius, two species that hybridize on Mt. Etna, Sicily. aethnensis is the high altitude species (>1600 m) and chrysanthemifolius is found from sea level up to ~1000 m. Hybrid swarms are common at intermediate altitudes.

After my initial field work, Etna decided to erupt, limiting slightly the work I wanted to carry out.... (BBC news, July, 2001).

So, I moved into the lab a little more!

Firstly, I looked into the genetic barriers to hybridization between the two species by performing a pollen competition experiment in the greenhouse. As we guessed, there was virtually no barrier to hybrid production in these two species (Chapman et al. 2005). In addition, hybrids (F1, F2 and backcross) are fit and fertile.

I then spent a little time looking at the ecological barriers (primarily temperature) that may be maintaining the hybrid zone. Firstly, the aethnensis seed germinate at lower temperatures compared to chrysanthemifolius and they also exhibit significantly different seed oil profiles, with aethnensis having more unsaturated fatty acids (FAs) than chrysanthemifolius. I am still looking into this at UGA.

In addition I used morphology and molecular markers to identify the non-hybrid parentage of two populations of plants from Sicily (Chapman and Abbott, 2005).

 My final year or so in the lab in St. Andrews involved isolating cycloidea like genes from Senecio vulgaris. This species is polymorphic for presence/absence of ray florets (picture)

In collaboration with Enrico Coen at the John Innes Centre we are identfying the genes responsible.

For part of my PhD I used DNA sequences of one of the cycloidea genes linked to the ray floret locus plus PgiC to determine the origin of tetraploid Senecio mohavensis (subsp. mohavensis and subsp. breviflorus). The tetraploid is morphologically almost identical to one parent, diploid S. flavus, which does not have ray florets, however whether S. mohavensis is an autopolyploid (with the ray gene introgressed from another species) or an allopolyploid had not been determined. I showed that S. mohavensis is an allopolyploid (Chapman [thesis], 2004).

2. St. Andrews is great!

Just visit it! I'd recommend:

Kinshaldy beach to see the seals

The Isle of May

The music quiz at the Cellar bar

Lafferty's Irish Bar