Download Billy West GEO 4300 Lit Review 2 Ishtiaq, F., Clegg, S. M., Phillimore

Billy West
GEO 4300
Lit Review 2
Ishtiaq, F., Clegg, S. M., Phillimore, A. B., Black, R. A., Owens, I. P. F. and
Sheldon, B. C. 2010. Biogeographical patterns of blood parasite lineage
diversity in avian hosts from southern Melanesian islands. Journal of
Biogeography, (2010) 37: 120–132.
Ishtiaq and Sheldon are both with the Edward Grey Institute in the University of
Oxford’s department of Zoology. Clegg and Black are both with the department of
Biology at Imperial College London. Phillimore and Owens too are with the
department of Biology at ICL, as well as being with the NERC Centre for Population
Biology at ICL.
2) Research Question/Problem
How do populations of the parasites Plasmodium and Haemoproteus vary due
to their spatial distribution across different islands of varying size in southwest
Pacific archipelagos, with specific regard to the population(s) of avian host genus
Zosterops?
3) General Background Knowledge for the Study
Species richness on islands is strongly correlated with island size, such that
larger islands have higher values of species richness; vector-borne parasites, such as
Plasmodium and Haemoproteus, that rely on a variety of host species (including
insects and birds) might thus be expected to fare better on larger islands with
correspondingly larger values of host species richness. Additionally, despite their
populations’ being geographically isolated on individual islands in a chain, the intraspecies diversity of such vector-borne parasites may not depend so much on that
given that avian hosts can allow for inter-island traffic.
4) Methods
The distribution and diversity of the parasite populations was determined by
testing enzymes from host Zosterops (Polymerase Chain Reaction, or PCR). Genetic
diversity in terms of both nuclear (i.e., species) and mitochondrial DNA was taken
into account. Statistical calculations were used to determine host and species’
spatial relationships (linear regressions for species-area and species-distance;
Mantel tests for distance-decay).
5) Results of the Study
The host bird and mosquito species showed strong species-area
relationships, while the parasite Plasmodium's populations showed relatively weak
such relationships and Haemoproteus' none at all. Species richness for the parasites
was more strongly correlated with avian species richness than with mosquito
species richness, and similarity between populations decreased with distance for
host species and Plasmodium, but not for Haemoproteus.
6) Weaknesses of the Study
While the inadequate sampling for species richness was statistically
corrected for, a larger sample would have obviated the need for corrective
techniques. Furthermore, the Mantel test is non-parametric and preferentially needs
larger samples than do parametric tests in order to be effective (this is unrelated to
the sample size for species richness).
7) What we learned new from the study
Species-distance relationships for parasites Plasmodium and Haemoproteus
are relatively weak, suggesting other factors are more important for species
richness on a single island, although distance between islands was generally a factor
in terms of genetic diversity.