If I can identify a common thread in my rather eclectic research background, it is a fascination with the processes maintaining and promoting biological diversity.
1. For my dissertation research, I considered adaptations that contribute to the maintenance of phenotypic diversity (in the form of stable polymorphisms) within populations. My research was conducted in the side-blotched lizard system (Uta stansburiana), under Barry Sinervo at UC Santa Cruz:
Polymorphic phenotypes ("morphs") tend to involve multiple, often unlinked traits that are differentiated on more than one axis (e.g., alternative mating, foraging, antipredator, and dispersal strategies). These alternative strategies, when present, are advantageous because they increase the niche breadth of the population. However, this advantage is potentially opposed by correlational selection (multivariate disruptive selection favoring alternative combinations of traits), which can impose a recombinational genetic load, lowering the fitness of the population.
Part of my research focused on identifying facultative maternal effect mechanisms which induce adaptive traits in offspring in a context-dependent manner, thus resolving correlational selection pressures and promoting phenoypic and genetic diversity within the population. (Lancaster et al. 2007, Ecology Letters; Lancaster et al. 2010, Evolution)
2. For my first postdoctoral research project at NCEAS, I examined factors promoting and maintaining species diversity in the California flora.
With Emma Goldberg and Rick Ree, I examined the role of the threatened and unique habitat of chaparral in promoting species diversification within two key California shrubs, Arctostaphylos and Ceanothus. These genera inhabit mesic, forest habitats in California as well as the dynamic, fire- and flood-prone, nutrient-poor, and arid chaparral habitats. Our study also piloted Emma's GeoSSE method for phylogenetic estimation of range shifts and habitat-dependent diversification. (Goldberg et al. 2011, Sys. Biol.)
With Kathleen Kay, I examined the historical factors of speciation, extinction, and migration that have contributed to the California Floristic Province's status as a biodiversity hotspot. We also examined classical hypotheses for California's diversity, which are: 1) its Mediterranean climate, and 2) its location at a broad ecotone between two Tertiary geofloras (Raven and Axelrod 1978). (Lancaster and Kay, accepted with revisions, Evolution)
3. For my work at Lund University, I will be studying adaptation at range limits in the polymorphic blue-tailed damselfly, Ischnura elegans. Range limits are thought to be maintained by a combination of gene flow and trade-offs: adaptations to extreme conditions at range limits are often in trade-off with traits that are more advantageous towards the center of the range. Gene flow from the center of the range prevents organisms at the edges from maximizing their fitness and adapting further to more extreme conditions (beyond the stable limits). Under conditions of climate change, environmental conditions ancestrally characterizing the center of the range are expected to shift towards the edges, such that range expansion is possible. We will look for the genetic and phenotypic signatures of expanding ranges, partially focusing on changes in genetic and phenotypic diversity and thermal adaptations to extremes of heat and cold. This work is largely to be carried out, but I will present some preliminary results on how sex, developmental phase, and polymorphism explain individual variation in response to extreme heat and cold within non-range-limit populations. These results suggest possible demographic changes under changing climates and at range limits.
For more information about each of these studies, and to access the manuscripts cited here, please visit my research website: http://www.nceas.ucsb.edu/~lancaster/Welcome.html.
Thanks for coming!!