These are just a few examples of papers that would fit the bill for your taxonomic paper,
but are not from the sort of straight-and-narrow pathway…. just to give you a sense of
what your range of options are. You can use these as a springboard for new ideas of your
own, or you are welcome to use any of these as well – but you should e-mail me to check
in if you’d like to do that. I don’t want too many people using the same paper(s), and one
of these examples is quite short and the paired paper would need to be selected carefully.
What I am trying to do here is mostly to encourage you to have fun with this assignment –
think about what your interests are, and how you could meld what you would like to learn
more about anyway with a taxonomic issue or question. There are articles that pertain to
taxonomy in the fields of conservation biology, forensic botany, paleobiology, and all sorts
of other issues I’m probably not thinking of. So be creative!
Cheers,
Priya
Brouat, C., D. McKey, et al. (2004). "Differentiation in a geographical mosaic of plants
coevolving with ants: phylogeny of the Leonardoxa africana complex (Fabaceae :
Caesalpinioideae) using amplified fragment length polymorphism markers." Molecular
Ecology 13(5): 1157-1171.
Comprising four allopatric subspecies that exhibit various grades of ant-plant
interactions, from diffuse to obligate and symbiotic associations, the Leonardoxa africana
complex (Fabaceae, Caesalpinioideae) provides a good opportunity to investigate the
evolutionary history of ant-plant mutualisms. A previous study of the L. africana complex
based on chloroplast DNA noncoding sequences revealed a lack of congruence between
clades suggested by morphological and plastid characters. In this study, we analysed
phylogenetic relationships within the L. africana complex using a Bayesian probability
approach on amplified fragment length polymorphism markers. The results reported
permit partial validation of the four subspecies of L. africana previously defined by
morphological and ecological markers. Incongruences between phylogenies based on
chloroplast DNA and amplified fragment length polymorphism markers are discussed in
the light of morphological and ecological data, and confronted with hypotheses of
convergence, lineage sorting and introgression.
Feild, T. S., N. C. Arens, et al. (2004). "Dark and disturbed: a new image of early
angiosperm ecology." Paleobiology 30(1): 82-107.
Better understanding of the functional biology of early angiosperms may clarify
ecological factors surrounding their origin and early radiation. Phylogenetic studies identify
Amborella, Nymphaeales (water lilies), Austrobaileyales, and Chloranthaceae as extant
lineages that branched before the radiation of core angiosperms. Among living plants,
these lineages may represent the best models for the ecology and physiology of early
angiosperms. Here we combine phylogenetic reconstruction with new data on the
morphology and ecophysiology of these plants to infer early angiosperm function. With
few exceptions, Amborella, Austrobaileyales, and Chloranthaceae share ecophysiological
traits associated with shady, disturbed, and wet habitats. These features include low and
easily light-saturated photosynthetic rates, leaf anatomy related to the capture of
understory light, small seed size, and clonal reproduction. Some Chloranthaceae,
however, possess higher photosynthetic capacities and seedlings that recruit in canopy
gaps and other sunny, disturbed habitats, which may have allowed Cretaceous
Chloranthaceae to expand into more diverse environments. In contrast, water lilies
possess ecophysiological features linked to aquatic, sunny habitats, such as absence of a
vascular cambium, ventilating stems and roots, and floating leaves tuned for high
photosynthetic rates in full sun. Nymphaeales may represent an early radiation into such
aquatic environments. We hypothesize that the earliest angiosperms were woody plants
that grew in dimly lit, disturbed forest understory habitats and/or shady streamside
settings. This ecology may have restricted the diversity of pre-Aptian angiosperms and
living basal lineages. The vegetative flexibility that evolved in the understory, however,
may have been a key factor in their diversification in other habitats. Our inferences based
on living plants are consistent with many aspects of the Early Cretaceous fossil record and
can be tested with further study of the anatomy, chemistry, and sedimentological context
of Early Cretaceous angiosperm fossils.
Kawakita, A., A. Takimura, et al. (2004). "Cospeciation analysis of an obligate pollination
mutualism: Have Glochidion trees (Euphorbiaceae) and pollinating Epicephala moths
(Gracillariidae) diversified in parallel?" Evolution 58(10): 2201-2214.
Species-specific obligate pollination mutualism between Glochidion trees
(Euphorbiaceae) and Epicephala moths (Gracillariidae) involves a large number of
interacting species and resembles the classically known fig-fig wasp and yucca-yucca
moth associations. To assess the extent of parallel cladogenesis in Glochidion-Epicephala
association, we reconstruct phylogenetic relationships of 18 species of Glochidion using
nuclear ribosomal DNA sequences (internal and external transcribed spacers) and those
of the corresponding 18 Epicephala species using mitochondrial (the cytochrome oxidase
subunit I gene) and nuclear DNA sequences (the arginine kinase and elongation factor1alpha genes). Based on the obtained phylogenies, we determine whether Glochidion and
Epicephala have undergone parallel diversification using several different methods for
investigating the level of cospeciation between phylogenies. These tests indicate that
there is generally a greater degree of correlation between Glochidion and Epicephala
phylogenies than expected in a random association, but the results are sensitive to
selection of different phylogenetic hypotheses and analytical methods for evaluating
cospeciation. Perfect congruence between phylogenies is not found in this association,
which likely resulted from host shift by the moths. The observed significant discrepancy
between Glochidion and Epicephala phylogenies implies that the one-to-one specificity
between the plants and moths has been maintained through a complex speciation process
or that there is an underestimated diversity of association between Glochidion trees and
Epicephala moths.
Percy, D. M., R. D. M. Page, et al. (2004). "Plant-insect interactions: Double-dating
associated insect and plant lineages reveals asynchronous radiations." Systematic
Biology 53(1): 120-127.
An increasing number of plant-insect studies using phylogenetic analysis suggest
that cospeciation events are rare in plant - insect systems. Instead, nonrandom patterns of
phylogenetic congruence are produced by phylogenetically conserved host switching ( to
related plants) or tracking of particular resources or traits ( e. g., chemical). The
dominance of host switching in many phytophagous insect groups may make the
detection of genuine cospeciation events difficult. One important test of putative
cospeciation events is to verify whether reciprocal speciation is temporally plausible. We
explored techniques for double-dating of both plant and insect phylogenies. We use dated
molecular phylogenies of a psyllid (Hemiptera) - Genisteae (Fabaceae) system, a
predominantly monophagous insect - plant association widespread on the Atlantic
Macaronesian islands. Phylogenetic reconciliation analysis suggests high levels of parallel
cladogenesis between legumes and psyllids. However, dating using molecular clocks
calibrated on known geological ages of the Macaronesian islands revealed that the
legume and psyllid radiations were not contemporaneous but sequential. Whereas the
main plant radiation occurred some 8 million years ago, the insect radiation occurred
about 3 million years ago. We estimated that >60% of the psyllid speciation has resulted
from host switching between related hosts. The only evidence for true cospeciation is in
the much more recent and localized radiation of genistoid legumes in the Canary Islands,
where the psyllid and legume radiations have been partially contemporaneous. The
identification of specific cospeciation events over this time period, however, is hindered by
the phylogenetic uncertainty in both legume and psyllid phylogenies due to the apparent
rapidity of the species radiations.
Sargent, R. D. (2004). "Floral symmetry affects speciation rates in angiosperms."
Proceedings of the Royal Society of London Series B-Biological Sciences 271(1539): 603608.
Despite much recent activity in the field of pollination biology, the extent to which
animal pollinators drive the formation of new angiosperm species remains unresolved.
One problem has been identifying floral adaptations that promote reproductive isolation.
The evolution of a bilaterally symmetrical corolla restricts the direction of approach and
movement of pollinators on and between flowers. Restricting pollinators to approaching a
flower from a single direction facilitates specific placement of pollen on the pollinator.
When coupled with pollinator constancy, precise pollen placement can increase the
probability that pollen grains reach a compatible stigma. This has the potential to generate
reproductive isolation between species, because mutations that cause changes in the
placement of pollen on the pollinator may decrease gene flow between incipient species. I
predict that animal-pollinated lineages that possess bilaterally symmetrical flowers should
have higher speciation rates than lineages possessing radially symmetrical flowers. Using
sister-group comparisons I demonstrate that bilaterally symmetric lineages tend to be
more species rich than their radially symmetrical sister lineages. This study supports an
important role for pollinator-mediated speciation and demonstrates that floral morphology
plays a key role in angiosperm speciation.
Stewart, C. N., G. Rosson, et al. (1996). "Population genetic variation in rare and
endangered Iliamna (Malvaceae) in Virginia." Biological Journal of the Linnean Society
58(3): 357-369.
Random amplified polymorphic DNA (RAPD) markers were used as input for an
analysis of molecular variance (AMOVA), homogeneity of molecular variance analysis
(HOMOVA), and cluster analysis to describe the population genetic structure of Ihiamna
corei, a federally endangered plant located only in Virginia, and I. remota, a rare plant in
Virginia, Indiana, and Illinois. The analysis was performed to help clarify the taxonomic
relationship between the two closely related species. We analysed four clones in the only
known population of I. corei, breeding stock derived from seeds originating from the
population site, and three I. remota populations in Virginia. Eighty-five percent of screened
primers revealed DNA polymorphisms in Ihiamna. Ninety-nine informative markers were
generated using seven primers. No significant statistical differences (at P = 0.05) in RAPD
variation was found between species (24% of variance) using the AMOVA procedure.
However, within species/among populations (31% of the variance) and within populations
(45% of the variance) there were significant differences (P < 0.002). An unweighted paired
group method using arithmetic averages (UPGMA) cluster analysis showed the federally
endangered I. corei population to be genetically distinct from the apparently recently
introduced (in Virginia: similar to 100 ybp) I. remota. The lack of significant differences
from the AMOVA and the high number shared bands between I. corei and I. remota
suggest that I. corei may be more appropriately classified as a subspecies of I. remota.
Ihiamna corei plants in the natural population were genetically similar to one another while
the I. corei breeding stock plants and I. remota plants were genetically relatively diverse.
(C) 1996 The Linnean Society of London
Stuessy, T. F., K. Tremetsberger, et al. (2003). "The melding of systematics and
biogeography through investigations at the populational level: examples from the genus
Hypochaeris (Asteraceae)." Basic and Applied Ecology 4(4): 287-296.
In recent years molecular data, especially from DNA, have provided more precise
estimates of relationships among vascular plants. Different types of data have been used
efficaciously at different levels of the taxonomic hierarchy from ordinal and familial
classifications to genetic variation within populations. The impact on systematics has been
enormous, often confirming previous hypotheses established through morphological or
other data, but sometimes offering novel and surprising insights. Although it is far from
clear which genes or intergenic regions will eventually be known to contain the most
helpful phylogenetic information for general and special classification, it is abundantly
clear that a genetic yardstick will be used routinely. The impact of molecular data on plant
systematics is now having a similar import in biogeography. Sequence data, as well as
DNA fingerprinting of various types, are now being employed to assess patterns of
isolation and speciation, timing of changes of distributions and speciation events, routes of
migration and/or dispersal, population-level divergence, and hybridization. Systematics
and biogeography, therefore, are melding together more closely than ever before,
because the same kinds of data can be used to address questions regarding evolutionary
relationships as well as patterns of distribution in space and time. Data at the populational
level are especially helpful in a multidisciplinary context for answering questions regarding
infraspecific affinities and for explaining distributions resulting from recent historical and
ecological factors. Examples from the genus Hypochaeris (Asteraceae) from southern
South America, using DNA sequence and AFLP data, are used to illustrate these points.
The genus appears to have originated in Eurasia, dispersed to South America during the
past several million years, and radiated into more than 45 species that are adapted to
many different ecological regimes.