NEO-ALLOPATRY. Invasive species as model systems for the study of the early stages of allopatric speciation.
Coordinator - Daniel Montesinos
Execution dates - 2016-01-01 - 2019-05-31 (41 Months)
Funding Entity - FCT
Funding for Grupo - 199 440.00 €
Total Funding - 199 440 €
Proponent Institution - Centro de Ecologia Funcional - Universidade de Coimbra
Participating Institutions
Durham University (UK)
Universidad Nacional de La Pampa (Argentina)
University of Wollongong (Australia)
York University (Canada)
The University of Montana (USA)

Invasive species are optimum model systems to understand the early stages of allopatric speciation. Since their distributions are typically allopatric among native and non-native regions, and approximate introduction dates to each region are often known, the rate at which adaptations develop can be determined. Genetic drift associated with founder events and colonization and adaptation to different environments lead to genetic divergence between native and non-native ranges. Divergent selection of ecological traits can drive reproductive isolation (RI) and, eventually, speciation. Invasives have been found to rapidly adapt to local conditions, and there is a strong correlation between adaptation and RI, with recent evidence for emerging RI between native and non-native ranges of an invasive species. However, it is unclear if newly developed reproductive barriers are adaptive, or if they appear as a side effect of other adaptive traits (pleiotropy). In either case, reproductive barriers should play an important role in the conservation and spread of locally adapted traits important for invasibility. However, there is limited experimental information on the mechanisms involved in the origin and spread of newly adapted traits, or on their genetic bases.

We aim to study the worldwide geographic mosaic of local adaptation and competitive ability of the annual herb Centaurea solstitialis. This is an ideal study system, since introduction dates are known, and it is native to Europe and invasive in several parts of the world (Australia, North and South America), in which it has developed different sets of local adaptations, including an incipient but significant degree of RI between some native and non-native regions. Traditional studies have limited their studies to quantify trait-shifts between native and non-native regions. However, for this proposal, we aim to use an absolutely novel approach by experimentally producing, by means of controlled cross-pollinations, inter-regional hybrids between each pair of regions, across all world regions with C. solstitialis presence.

We will experimentally produce F1 and F2 generations of within-region and inter-regional hybrid individuals between each pair of regions in order to study fitness components across the worldwide geographic mosaic of local adaptation, competitive ability and RI. We will also determine the genetic basis of invasive evolutionary change by using genetic and quantitative trait locus (QTL) mapping to investigate the genetic architecture of quantitative trait variation and emerging RI, and to correlate it to fitness levels detected in common garden experiments. The ecological and genetic study of the heritability of different local traits on these inter-regional hybrids will allow us to assess the dominance of expression of new local adaptations in allopatry, and the role of reproductive barriers in favoring or limiting the spread of locally adapted traits in the event of population reinforcements with non-adapted individuals from other regions (e.g. new introductions of seeds from the native range in the invaded range).

Overall, this project aims to elucidate the ecologic and genetic mechanisms involved in the early stages of allopatric speciation, a keystone concept of evolutionary biology, in order to address how repeatable is evolutionary change resulting in invasiveness. Repeated and predictable evolution of invasiveness would enable the development of universal strategies to combat the problem while region-specific evolution would require the development of local targeted strategies for maximum effect.