CONTENT - International Society of Zoological Sciences

S2 ICZ2008 - Abstracts
Closing the ring: biogeography of the salamander ring species
Ensatina eschscholtzii
Shawn R. Kuchta 1 , Duncan Parks 2 , Rachel Lockridge Mueller 3 and
David B. Wake 4
1
Lund University, Department of Animal Ecology, Ecology Building,
Sölvegatan 37, SE-223 62, Lund, Sweden
2
Mt. Angel Seminary, St. Benedict, OR 97373, USA
3
Department of Biology, Colorado State University, Fort Collins, CO
80523-1878, USA
4
Museum of Vertebrate Zoology, Department of Integrative Biology,
University of California Berkeley, Berkeley, CA 94720-3160, USA
Ring species exhibit a circular arrangement of populations around a
central barrier, with reproductively isolated parts overlapping at one
point in the ring, yet morphological and genetic intergradation
elsewhere. They evolve when two or more lineages descend from a
common ancestor and become reproductively isolated while
maintaining their connectivity through a chain of interbreeding
populations. The salamander Ensatina eschscholtzii is a classic
example of a ring species. In the original biogeographical scenario,
the point of ring closure was situation in southern California, USA.
Here we develop an alternative biogeographic scenario that is
informed by the geomorphological development of California, and
situates the point of ring closure in central coastal California. To
distinguish between these two biogeographical alternatives, mtDNA
sequence data was collected from 385 individuals from 224
populations, and a Bayesian phylogeny was inferred. The two
biogeographical scenarios were tested against our Bayesian
topology, including the associated Bayesian 95% credible set of
trees. Our Bayesian topology contradicts the new biogeographic
hypothesis.
Evolution of the chromosomal organization in the Sophophora
subgenus of Drosophilidae : the nucleolus organizer region
Laurence Monti 1,2 , Nicole Chaminade 2 , Jean-Luc Da Lage 2 , Marie-Louise
Cariou 2 , Françoise Lemeunier 2 and Sylvie Aulard 2
1 present address: Laboratoire Stress, Défenses et Reproduction des
Plantes, Université de Reims, Champagne, Ardenne. Campus Moulin de
la Housse Bat 8 – BP 1039 51687 Reims cedex 2, France
2 Laboratoire Evolution, Génomes et Spéciation, CNRS, Avenue de la
Terrasse, 91198 Gif-sur-Yvette cedex, France
In Drosophila, the heterochromatic sequences are found into specific
chromosomal regions and submitted to rapid evolution. Due to its
heterochromatic localisation, and its highly conserved structure in Insects,
the nucleolus organizer region (NOR) is a useful tool to study the
rearrangements of the chromosomal architecture.
Using fluorescent in situ hybridization, we have analysed 54 species
belonging to different groups of the Sophophora subgenus.
The presence of one NOR on each sexual chromosome (X and Y), already
known in Drosophila melanogaster, has been detected for the 16 other
species studied in the melanogaster group. However, NORs on the Y
chromosome of D. simulans and D. sechellia have lost the 28s rDNA
genes.
In the 26 species of the montium group, the NORs are also localised on the
sex chromosomes but their number can vary between 1 and 3, which
implies the loss or the gain of a NOR in some species. In conclusion, the
presence of NORs on sexual chromosomes is an ancestral feature for
these two groups.
On the contrary, the 12 species of the ananassae group show quite
different pattern, most of them showing only one NOR, on chromosome 4.
This could be related to data on chromosomal evolution that point
out the hypothesis of a translocation between the X or the Y
chromosome (depending on authors) and chromosome 4 in D.
ananassae. Such an event could explain the presence of the NOR
on this autosome without rejecting that NORs on sexual
chromosomes are ancestral for the Sophophora subgenus.
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The Crassostrea oyster species in China
Haiyan Wang 1,2 , Guofan Zhang 1 , Xiao Liu 1 and Ximing Guo 2
1Institute
of Oceanology, Chinese Academy of Sciences, Qingdao,
Shandong, PRC
2
Haskin Shellfish Research Laboratory, Institute of Marine and
Coastal Sciences, Rutgers University, Port Norris, New Jersey, USA
China is the home to many oyster species. Crassostrea species are
most common and commercially important in China. There is
considerable confusion about the classification of Crassostrea
species in China. In the past five years, we collected and analyzed
thousands of oysters at typical sites along the coast of China. By
comparing the morphology and sequences of 16S, COI and 28S
gene, we found seven Crassostrea species occurring along the coast
of China. One of our studies is on the taxonomic status of the red
and white forms of C. rivularis (Gould, 1861), which shows that the
red oyster is the same species as C. ariakensis; the white oyster is
the same species as a newly described species, C. hongkongensis
(Wang et al., 2004). Another study is on the classification of small
cupped oysters along the coast of China, which includes three
species, C. gigas, C. angulata and C. sikamea. Recently we found
that C. nippona and C. iredalei were also presented in China. Our
studies clarified the classification of Crassostrea species in China,
providing basic information for oyster classification, aquaculture and
the protection of oyster resources in China.
Guo X., S. Ford and F. Zhang. 1999. J. Shellfish Res., 18:19-31.
Wang H. and X Guo, 2008. J. Shellfish Res., 27(3):481-487.
Wang H., X. Guo, G. Zhang and F. Zhang. 2004. Aquaculture (242):
137-155.
Wang H., G. Zhang, X. Liu and X. Guo. 2008. J. Shellfish Res.,
27(3):495-503.
The unexpected ecology of allopatric speciation
John Wiens
New York, 11794-5245, Stony Brook, U.S.A.
Allopatric speciation is widely considered to be the most common of
the thre geographic modes. Yet, there has been suprisingly little
focus on the evolutionary and ecological processes that cause
species to become allopatric. In this talk, I will discuss recent
research from my lab looking at this neglected aspect of speciation.
Consideration of how a species becomes split into allopatric populat!
ions leads to an unexpected view: that the key to geographic
isolation is not necessarily the adaptive divergence of different
populations, but rather the failure of an ancestral species to adapt to
environmental change in part of its geographic range. Thus, the
ecological similarity of species over time (niche conservatism) may
often be essential to their geographic isolation; if all species could
quickly adapt to any environmental conditions, there would be few
geographic barriers to gene flow and little allopatric speciation. I will
describe how we have tested and supported this model of allopatric
speciation through niche conservatism in North American
salamanders. However, the situation is more complicated in tropical
salamanders, where closely related species tend to occur in
dissimilar environments. Explanations for these divergent patterns
will be addressed, along with their implications for the causes of the
latitudinal diversity gradient. Research on the evol! utionary ecology
of allopatry will be placed within the larger conceptual framework of
speciation research. Finally, the relationships between speciation,
niche conservatism, and other topics in ecology and evolution will be
discussed (e.g., responses to climate change, spread of invasive
species, community assembly, historical biogeography).