Research
We typically use various species of fish to address these issues and use a range of approaches from molecular to morphological to understand how evolution occurs. Recent research has used adaptive radiations of African cichlids, adaptively divergent populations of Arctic charr, and populations of
sticklebacks inhabiting geothermally heated waters. We even cause evolution in the lab by selecting phenotypic variation in lines of zebrafish derived from wild
populations. Together this range of projects creates a dynamic lab environment covering a range of integrative research.
Research areas
Bone and craniofacial development
Adaptive radiations in vertebrates are often characterized by variation in the face. This is likely because the craniofacial apparatus provides a direct interface with prey providing a key target for ecological selection. The changes brought about by selection in the face are underlain by developmental processes that determine what variation is available for evolution. Specifically, we are interested in characteristics of bone development in the facial region including how it initially forms, ossifies, and how these alter functional abilities. We employ a range of methods including QTL mapping, population genomics, and a range of developmental genetic approaches to understand how phenotypes are achieved. We also assess the performance of these traits so that we can better understand their adaptive importance.
We take a broad approach towards understanding biodiversity which takes into account the interactions that take place between evolution, ecology, and development. This emerging 'eco-evo-devo' view takes a realistic view toward how adaptive phenotypes are formed as genes (as well as additional inheritance systems) and the environment interact ubiquitously during development. In short, we embrace complexity and our research typically takes a 'phenotype first' approach toward the connections we make to mechanisms of adaptive divergence.
Adult and embryonic stages of sticklebacks stained to accentuate bone and cartilage
Phenotypic plasticity
Development cannot occur without influences from the environment. Over the past decade it has become much more widely accepted that environmental conditions can contribute phenotypic variation that is important for adaptive evolution. We approach the topic of phenotypic plasticity by taking advantage of a strong theoretical framework to examine the mechanistic basis of plasticity. This includes determining what genetic and epigenetic variation controls plasticity, and how these mechanisms have changed across cases of adaptive divergence.
Identifying candidate genes for plastic responses and genetic assimilation in Malawi cichlids
Non-genetic inheritance
Heritability was once thought to exclusively be a genetic phenomenon but it is now appreciated that several other types of inheritance systems exist. This includes epigenetic and parental effects whereby the previous generation can influence the current one based on its experiences. We are actively examining the phenotypic outcomes of maternal effects over multiple generations of cichlids, and have recently embarked on a muli-generation project examining how variation in natural geothermally-heated populations of stickleback can influence a range of phenotypes. Our approaches are experimental, and we complement this with sequencing approaches (i.e. bisulphite sequencing) which complement our interests. Ultimately these less appreciated forms of inheritance can play a role in determining how evolution proceeds, and be especially important for determining how the genome is exposed to selection through the phenotype.
Cichlid brains respond to the presence or absence of maternal care
Conservation Evo-Devo
Human activity is causing a range of challenges for biodiversity. Conservation as a field is benefiting from the incorporation of evolutionary theory but we contend that this hasn't extended into the advances made by evo-devo. Development will be among the first aspects of an organism to change in an altered environment, and this change will precede the current empirical monitoring strategies employed within conservation (i.e. demography, and genetic variation). Thus, phenotypic development can be used as a monitoring tool, or studied in experiments that emulate predicted changes in environments. Further, conservation practises that aim to preserve the evolutionary process must take evolvablity (the ability of a population to produce adaptive variation) into account rather than aim to preserve populations on the basis of shear amounts of molecular genetic variation (much of which will be neutral).
Currently we are interested in factors such as overharvesting, and climate change. Specifically projects focused on fisheries-induced evolution and how harvesting can change the developmental environment are being conducted. Another major project is focused on the long-term effects of increased temperature by comparing natural populations of fish from geothermally heated environments to those from neighboring ambient temperature environments.
Unifying evo-devo's strands
The greatest advances in evolutionary biology have been the outcome of major syntheses (i.e. the modern synthesis). Yet, since evo-devo gained momentum in the 1990s to the present it has largely advanced along two distinct lines of research. One being largely typological and focused on the molecular basis of discrete, qualitative shifts in phenotype. The other has been heavily quantitative with a focus on describing developmental phenomena (e.g., phenotypic integration) largely through morphometrics of complex phenotypes. We have recently argued in TREE (Parsons and Albertson, 2013), that integrating these views holds tremendous potential for evo-devo to reach its full potential. Most traits that evolve in nature are in fact complex, part of a continuum, variable, and quantitative yet we know very little about the molecular mechanisms which determine them. Therefore we use a practical road map to discover the genetic and/or developmental basis of continuous and complex adaptive phenotypes in non-model organisms.
A 3d model of a cichlid mandible used to relate shape to genetic variation