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David L. Stern| Stern Lab Webpage | |
| This e-mail address is being protected from spam bots, you need JavaScript enabled to view it | Assistant: |
| Guyot Hall-M166 | This e-mail address is being protected from spam bots, you need JavaScript enabled to view it |
| Phone: 609-258-0759 | 609-258-7127 |
Evolutionary developmental biology
Our research addresses biological problems arising at the interface of evolution and development. How does development evolve on a short time scale, within and between closely related species, to generate phenotypic variation? What are the genetic mechanisms regulating polyphenisms and other dramatic life-history switches? We address these questions using genetic, molecular and developmental techniques. For studying the problem of variation we primarily work with the fruit fly Drosophila melanogaster and closely related species. We study polyphenisms in the pea aphid (Acyrthosiphon pisum).
Variation
The first problem in evolution is variation. Hence, evolutionary biologists have invested heavily into studies of both genetic and phenotypic variation. Despite this effort, and an increasing understanding of development itself, we currently have almost no idea how genetic variation is transformed into phenotypic variation. The predominant model in evolutionary biology, traceable back to Darwin, suggests that continuous variation within populations is gradually selected upon to generate species differences. Further, the model suggests, this continuous variation is likely to be generated by a large number of loci each of small effect. It is true that quantitative variation abounds in natural populations and it is plausible to extrapolate from this variation to species differences. However, there is little empirical evidence to support or reject this view. It remains possible that most species differences do not arise from standing variation, but instead represent rare variants that are rapidly swept through populations. We require data on the actual genetic differences that generate variation within and between species.
We have begun by studying the developmental genetics underlying variation in two pieces of morphology, the distribution of trichomes on the legs (Stern 1998) and on the dorsum of larvae (Sucena & Stern 2000). In the legs of Drosophila, we discovered that the precise spatio-temporal expression of Ultrabithorax (Ubx) protein is required to generate the distribution of naked cuticle and trichomes. Ubx is expressed in a gradient in the leg where high levels repress trichomes and lower levels do not. We found that evolution at the Ubx locus contributes to a difference in this trait between Drosophila melanogaster and D. simulans and this difference appears to be due to evolution of cis-regulatory DNA. This is the first experimental demonstration that evolution of Hox gene patterning is responsible for an interspecific morphological difference.
On the dorsum of first instar larvae, the distribution of trichomes differs between D. sechellia and its close relatives. We have discovered that this difference is due entirely to cis-regulatory evolution of the gene shavenbaby/ovo. Our current studies are aimed at identifying the nucleotide changes responsible for these and other evolutionary transitions.
Aphid development and genetics
Many organisms have evolved to cope with predictably variable environments by producing specific adaptive phenotypic changes. In one of its most extreme incarnations, aphid clones respond to seasonal and other environmental changes by producing alternative morphs in different generations. For example, in the summer, aphids produce apterous morphs that feed until the host plant becomes crowded, they then produce a generation of winged individuals that found new colonies on distant plants. In some species, aphid clones can produce more than eight distinct morphs. Although the environmental cues that induce alternative morphs are well understood, the genetic control of these polyphenisms is mysterious. We are using genetic and genomics approaches to unravel the genetic control of aphid polyphenisms in the pea aphid, Acyrthosiphon pisum.
Selected Publications
Orgogozo V, Stern DL. (2009) How different are recently diverged species?: More than 150 phenotypic differences have been reported for the D. melanogaster species subgroup. Fly (Austin). 3. [Epub ahead of print]
Stern DL, Orgogozo V. (2009) Is genetic evolution predictable? Science. 2009 323: 746-751. PubMed
Stern DL, Orgogozo V. (2008) The loci of evolution: How predictable is genetic evolution? Evolution 62: 2155-2177. PubMed
Rockman MV, Stern DL. (2008) Tinker where the tinkering's good. Trends Genet 24: 317-319. PubMed
Stern DL. (2008) Aphids. Curr Biol 18: R504-505. PubMed
Orgogozo V, Muro NM, Stern DL. (2007) Variation in fiber number of a male-specific muscle between Drosophila species: a genetic and developmental analysis. Evol Dev 9: 368-377. PubMed
McGregor AP, Orgogozo V, Delon I, Zanet J, Srinivasan DG, Payre F, Stern DL. (2007) Morphological evolution through multiple cis-regulatory mutations at a single gene. Nature.448: 587-590. PubMed
Stern DL. (2007) The developmental genetics of microevolution. Novartis Found Symp 284: 191-200; discussion 200-206. PubMed
McGregor AP, Orgogozo V, Delon I, Zanet J, Srinivasan DG, Payre F, Stern DL (2007). Morphological evolution through multiple cis-regulatory mutations at a single gene. Nature 448: 587-590. PubMed
Davis GK, Srinivasan DG, Wittkopp PJ, Stern DL (2007). The function and regulation of Ultrabithorax in the legs of Drosophila melanogaster. Dev Biol 308: 621-631. PubMed
Brisson JA, Davis GK, Stern DL (2007). Common genome-wide patterns of transcript accumulation underlying the wing polyphenism and polymorphism in the pea aphid (Acyrthosiphon pisum). Evol Dev 9: 338-346. PubMed
Orgogozo V, Muro NM, Stern DL (2007). Variation in fiber number of a male-specific muscle between Drosophila species: a genetic and developmental analysis. Evol Dev 9: 368-377. PubMed
Brisson JA, Stern DL (2006). The pea aphid, Acyrthosiphon pisum: an emerging genomic model system for ecological, developmental and evolutionary studies. Bioessays.28: 747-755. PubMed
Stern DL (2006). Developmental biology. Morphing into shape. Science 313: 50-51. PubMed
Orgogozo V, Broman KW, Stern DL (2006). High-resolution QTL mapping reveals sign epistasis controlling ovariole number between two Drosophila species. Genetics 173: 197-205. PubMed
Hittinger CT, Stern DL, Carroll SB (2005). Pleiotropic functions of a conserved insect-specific Hox peptide motif. Development 132: 5261-5270. PubMed
Shingleton AW, Das J, Vinicius L, Stern DL (2005). The temporal requirements for insulin signaling during development in Drosophila. PLoS Biol 3: e289. PubMed
Shingleton AW, Stern DL, Foster WA (2005). The origin of a mutualism: a morphological trait promoting the evolution of ant-aphid mutualisms. Evolution Int J Org Evolution 59: 921-926. PubMed
Braendle C, Friebe I, Caillaud MC, Stern DL (2005). Genetic variation for an aphid wing polyphenism is genetically linked to a naturally occurring wing polymorphism. Proc Biol Sci 272: 657-664. PubMed
Braendle C, Caillaud MC, Stern DL (2005). Genetic mapping of aphicarus -- a sex-linked locus controlling a wing polymorphism in the pea aphid (Acyrthosiphon pisum). Heredity 94: 435-442. PubMed
Frankino WA, Zwaan BJ, Stern DL, Brakefield PM (2005). Natural selection and developmental constraints in the evolution of allometries. Science 307: 718-720. PubMed
Das J, Miller ST, Stern DL (2005). Comparison of diverse protein sequences of the nuclear-encoded subunits of cytochrome C oxidase suggests conservation of structure underlies evolving functional sites. Mol Biol Evol 21: 1572-1582. PubMed
Braendle C, Miura T, Bickel R, Shingleton AW, Kambhampati S, Stern DL (2003). Developmental origin and evolution of bacteriocytes in the aphid-Buchnera symbiosis. PLoS Biol 1: E21. PubMed
Sucena E, Delon I, Jones I, Payre F, Stern DL (2003). Regulatory evolution of shavenbaby/ovo underlies multiple cases of morphological parallelism. Nature 424: 935-938. PubMed
Shingleton AW, Sisk GC, Stern DL (2003). Diapause in the pea aphid (Acyrthosiphon pisum) is a slowing but not a cessation of development. BMC Dev Biol 3:7. PubMed
Stern DL (2003). The Hox gene Ultrabithorax modulates the shape and size of the third leg of Drosophila by influencing diverse mechanisms. Dev Biol 256: 355-366. PubMed
Stern DL (2003). Gene regulation. In: Keywords and Concepts in Evolutionary Developmental Biology. Eds: Hall B and Olson W. Harvard University Press pp 145-151.
Miura T, Braendle C, Shingleton A, Sisk G, Kambhampati S, Stern DL (2003). A comparison of parthenogenetic and sexual embryogenesis of the pea aphid Acyrthosiphon pisum (Hemiptera: Aphidoidea). J Exp Zoolog B Mol Dev Evol 295: 59-81. PubMed
Shingleton AW, Stern DL (2003). Molecular phylogenetic evidence for multiple gains or losses of ant mutualism within the aphid genus Chaitophorus. Mol Phylogenet Evol 26: 26-35. PubMed
Stern DL (2000). Evolutionary developmental biology and the problem of variation. Evolution Int J Org Evolution 54: 1079-1091. PubMed
Sucena E and Stern DL (2000). Divergence of larval morphology between Drosophila sechellia and its sibling species caused by cis-regulatory evolution of ovo/shaven-baby. Proc Natl Acad Sci USA 97: 4530-4534. PubMed
Stern DL and Emlen DJ (1999). The developmental basis for allometry in insects. Development 126: 1091-1101. PubMed
Stern DL (1998). A role of Ultrabithorax in morphological differences between Drosophila species. Nature 396: 463-466. PubMed