Review Proposal
Emerging Model Systems for the Study of Ecology and Evolution
Arkhat Abzhanov1, Justin Borevitz2, Cassandra Extavour1, John Finnerty3, Andrew
Groover4, Scott Hodges5, Hopi Hoekstra1, Elena Kramer1, Christopher Lowe6, Antonia
Monteiro7, Mike Shapiro8, John Willis9
1
Dept. of Organismic and Evolutionary Biology, Harvard University
2
Dept. of Ecology and Evolution, University of Chicago
3
Dept. of Biology, Boston University
4
Dept. of Plant Biology, Univ. of CA, Davis; USDA Forest Service, Institute of Forest
Genetics
5
Dept. of Ecology, Evolution and Marine Biology, Univ. of CA, Santa Barbara
6
Dept. of Organismal Biology and Anatomy, Univ. of Chicago
7
Dept. of Ecology and Evolutionary Biology, Yale Univ.
8
Dept. of Biology, Univ. of Utah
9
Dept. of Biology, Duke Univ.
The modern field of molecular developmental evolution (evo-devo) was largely founded
on comparisons that were drawn among existing model species such as Drosophila (fruit
fly), Caenorhabditis (nematode), Mus (mouse) and Gallus (chick). It has rapidly become
clear, however, that since phylogenetic position and the availability of ecological
information was not generally considered as a factor when these models were selected,
new model systems are needed in order to achieve a better understanding of many
questions related to aspects of evolution and ecology. The development of these new
models is not trivial, however, and requires a significant investment in money and time.
Therefore, it is critical to make wise choices and, to these ends, we have outlined the
fundamental characteristics and tools that are essential to any new system. An important
corollary to these criteria is the nature of the research questions that are being asked.
Therefore, we also review the diverse array of topics that the new model systems
currently under development will help us to understand, including the genetic basis for
speciation and adaptation, the evolution of morphological and ecological novelty, and the
nature of the metazoan genetic toolkit. Finally, we provide a brief overview of a wide
range of model systems that are poised to elucidate these questions as well as many
others. Featured systems include: Geospiza (Darwin's finch; Grant et al. 2006),
Peromyscus (wild mice; Hoekstra 2006; Storz and Hoekstra 2007), Gasterosteus
(stickleback; Peichel et al. 2001; Shapiro et al. 2004; Peichel 2005), Parhyale (sand flea;
Extavour and Akam 2003; Extavour 2005), Nematostella (star anemone; Putnam et al.
2007; Reitzel et al. 2007), Bicyclus (a butterfly; Ramos and Monteiro 2007), Aquilegia
(columbine; Whittall and Hodges 2007) and Populus (poplar; Brunner et al. 2007).
Brunner AM, DiFazio SP, Groover AT (2007) Forest genomics grows up and branches
out. New Phytologist 174(4): 710-713.
Extavour CG (2005) The fate of isolated blastomeres with respect to germ cell formation
in the amphipod crustacean Parhyale hawaiensis. Developmental Biology 277(2):
387-402.
Extavour CG, Akam M (2003) Mechanisms of germ cell specification across the
metazoans: epigenesis and preformation. Development 130(24): 5869-5884.
Grant PR, Grant BR, Abzhanov A (2006) A developing paradigm for the development of
bird beaks. Biological Journal of the Linnean Society 88(1): 17-22.
Hoekstra HE (2006) Genetics, development and evolution of adaptive pigmentation in
vertebrates. Heredity 97(3): 222-234.
Peichel CL (2005) Fishing for the secrets of vertebrate evolution in threespine
sticklebacks. Developmental Dynamics 234(4): 815-823.
Peichel CL, Nereng KS, Ohgi KA, Cole BLE, Colosimo PF et al. (2001) The genetic
architecture of divergence between threespine stickleback species. Nature
414(6866): 901-905.
Putnam NH, Srivastava M, Hellsten U, Dirks B, Chapman J et al. (2007) Sea anemone
genome reveals ancestral eumetazoan gene repertoire and genomic organization.
Science 317(5834): 86-94.
Ramos DM, Monteiro A (2007) Transgenic approaches to study wing color pattern
development in Lepidoptera. Molecular Biosystems 3(8): 530-535.
Reitzel AM, Burton PM, Krone C, Finnerty JR (2007) Comparison of developmental
trajectories in the starlet sea anemone Nematostella vectensis: embryogenesis,
regeneration, and two forms of asexual fission. Invertebrate Biology 126(2): 99112.
Shapiro MD, Marks ME, Peichel CL, Blackman BK, Nereng KS et al. (2004) Genetic
and developmental basis of evolutionary pelvic reduction in threespine
sticklebacks. Nature 428(6984): 717-723.
Storz JF, Hoekstra HE (2007) The study of adaptation and speciation in the genomic era.
Journal of Mammalogy 88(1): 1-4.
Whittall JB, Hodges SA (2007) Pollinator shifts drive increasingly long nectar spurs in
columbine flowers. Nature 447(7145): 706-U712.
Figure. This model represents the spectrum of genetic and genomic tools that can be
developed for new model systems. The outermost whorl represents the major
criteria used to select the new system, e.g., is the taxon a representative of a
critical evolutionary transition, often a deep evolutionary node, or is it a model for
recent evolutionary radiation? The next three whorls represent tools that are
essential to a successful model. We believe that deep EST sequencing and
optimized expression protocols are critical and the taxon must either be easily
culturable in the lab or obtainable in nature. The innermost whorls represent tools
that are undeniably useful but not necessarily critical, depending on the types of
questions that are being targeted. While a major model system would be expected
to possess all of these tools, models for speciation, for example, require the ability
to do genetics whereas models for ancient evolutionary transitions may not.