Carolyn J. Ferguson

The Decline of Plant Collecting in the United States: A Threat to the Infrastructure of Biodiversity Studies

Abstract Collections of plant specimens are the basic infrastructure for all studies of plant diversity, but there is concern that plant collecting is in decline. We acquired collection data from a diverse sample of 71 herbaria to test whether there is a decrease in rates of local collecting in the United States. The recorded data were the decade of collection for all specimens of nine exemplar genera from the local region of the herbarium. All analyses showed evidence of a decline in local collecting. We found that the temporal pattern of collecting varied considerably from herbarium to herbarium, but that more herbaria showed a decreasing trend than an increasing trend. The total accumulation of specimens is in decline and only 21% of the sampled herbaria reached their peaks in local collecting activity in the last 20 years. Furthermore, two thirds of the herbaria acquired fewer locally-collected specimens in the last two decades than in the prior two. These trends were consistent over all size classes of herbaria and over herbaria from all regions, though they were less severe in the Mountain region herbaria. Tests for bias indicated that our sample of herbaria was more active than typical, thus our conclusions should be considered a conservative estimate of decline.

Thirteen decades of foliar isotopes indicate declining nitrogen availability in central North American grasslands

*Humans are increasing both the deposition of reactive nitrogen (N) and concentrations of atmospheric CO(2) on Earth, but the combined effects on terrestrial ecosystems are not clear. In the absence of historical records, it is difficult to know if N availability is currently increasing or decreasing on regional scales. *To determine the nature and timing of past changes in grassland ecosystem dynamics, we measured the composition of stable carbon (C) and N isotopes in leaf tissue from 545 herbarium specimens of 24 vascular plant species collected in Kansas, USA from 1876 to 2008. We also parameterized a simple model of the terrestrial N cycle coupled with a stable isotope simulator to constrain processes consistent with observed patterns. *A prolonged decline in foliar N concentrations began in 1926, while a prolonged decline in foliar delta(15)N values began in 1940. Changes in the difference between foliar and atmospheric C isotopes reveal slightly increased photosynthetic water use efficiency since 1876. *The declines in foliar N concentrations and foliar delta(15)N suggest declining N availability in these grasslands during the 20th century despite decades of anthropogenic N deposition. Our results are consistent with progressive-nitrogen-limitation-type hypotheses where declines in N availability are driven by increased ecosystem N storage as a result of increased atmospheric CO(2).

A chloroplast DNA phylogeny of eastern Phlox (Polemoniaceae): implications of congruence and incongruence with the ITS phylogeny

The comparison of independent phylogenies is a valuable approach to the study of evolutionary pattern and process. Available data on eastern North American Phlox, including our recent ITS phylogeny, suggest that relationships are complicated in the group and that hybridization may have been a contributing factor. We used restriction site data from the chloroplast genome to develop a second phylogeny for eastern Phlox. Sampling was the same as that for the ITS study and consisted of 79 samples (including all 22 eastern Phlox species and most eastern subspecies, as well as multiple populations of many taxa). The resulting cpDNA phylogeny agrees with the ITS phylogeny in many respects, strengthening earlier conclusions. Nevertheless, incongruence between the trees is noteworthy: many samples, particularly of members of the P. pilosa and P. glaberrima complexes, are placed in different clades. A variety of tests were carried out to assess congruence in terms of topological patterns, character congruence, and homogeneity of data sets. Significant conflict between the phylogenies is discussed in light of the hypothesis that hybridization has affected relationships in this genus.

Implications of the Decline in Plant Collecting for Systematic and Floristic Research

In a companion paper in this issue, we have shown that plant collecting in the U.S. is in decline (Prather et al. 2004). We focused on the U.S. only because it was relatively easy for us to measure collecting there, but we are concerned that the decline in collecting may be pervasive worldwide. Because specimens are the fun damental records of biodiversity, we believe that this has serious ramifications in many arenas, particularly in systematic and floristic research, but also in conser vation biology, land management, and education, to name only the most obvious. Here we elaborate on the importance of collecting, even in the United States where the flora is relatively well-known. We further discuss some of the many causes of the decline, and encourage the systematics community to advocate con tinued plant collecting. Curators of collections and floristic researchers are

Relationships of Eastern North American Phlox (Polemoniaceae) based on ITS Sequence Data

Phylogenetic relationships of eastern Phlox (Polemoniaceae) are examined using sequence data from the internal transcribed spacer (ITS) region of the nuclear ribosomal DNA. Eastern North American Phlox species have been the focus of many evolutionary studies, and hybridization is thought to have played a role in the origin and evolution of some taxa. The phylogenetic information presented here leads to several important conclusions relevant to taxonomy, notably that Wherrys sections Phlox and Aiinnuae are not mono- phyletic, and that the eastern mat-forming taxa and the annuals of central Texas each form monophyletic groups. Neither of the two large species complexes in the east, the P pilosa complex and the P glaberrima complex, is monophyletic in the ITS tree. While the tree is consistent with a history of hybridization, the ITS data do not directly support previous hypotheses of hybrid origin of particular taxa.

Polemoniaceae phylogeny and classification: implications of sequence data from the chloroplast gene ndhF

The chloroplast gene ndhF was used to study phylogenetic relationships of the Polemoniaceae at two levels: among members of the Ericales and among genera of the family. Sequence data for interfamilial analyses consisted of 2266 bp for 14 members of the Ericales, including four species of the Polemoniaceae, plus three outgroup taxa. The Polemoniaceae were found to be related to Diospyros, Fouquieria, the Primulales, Rhododendron, and Impatiens, but relationships among taxa were generally not well supported. The precise position of the Polemoniaceae within the Ericales remains obscure. Data for intrafamilial analyses consisted of 1031 bp for 27 species of the Polemoniaceae, including at least one species from most genera of the family, plus five outgroup taxa. A single most parsimonious tree was identified. The analyses suggested that subfamily Cobaeoideae, excluding Loeselia, is monophyletic and that Huthia is sister to Cantua. Acanthogilia was sister to the remainder of subfamily Cobaeoideae. Subfamily Polemonioideae plus Loeselia formed four subclades that were strongly supported as monophyletic and represent the major lineages of the subfamily.

Intraspecific cytotypic variation and complicated genetic structure in the Phlox amabilis-P. woodhousei (Polemoniaceae) complex.

PREMISE OF THE STUDY Polyploidy is widely recognized as an important process in the evolution of plants, but less attention has been paid to the study of intraspecific polyploidy, including its prevalence, formation, taxonomic implications, and effect on genetic diversity, structure, and gene flow within and among individuals and populations. Here we studied intraspecific ploidy level variation in the Phlox amabilis-P. woodhousei complex to determine the amount and distribution of cytotypic and genetic variation present and measure the extent of gene flow among species, cytotypes, and populations. METHODS Flow cytometry and microsatellite analyses were used to ascertain cytotypic variation, genetic diversity, and population structure within and among eight populations of P. amabilis and 10 populations of P. woodhousei from Arizona and New Mexico. KEY RESULTS Our analyses support the recognition of P. amabilis and P. woodhousei as two distinct species. Both species exhibit cytotypic variation with geographically structured diploid, tetraploid, and hexaploid populations, and genetic analyses suggest a combination of auto- and allopolyploidy in their formation. Diploid, tetraploid, and most hexaploid populations within species share much of their genetic variation, while some hexaploid populations are genetically distinct. All populations maintain moderately high genetic diversity and connectivity, and genetic structure is strongly influenced by geography. CONCLUSIONS This study highlights the potential for complicated patterns of genetic variation relative to cytotypic variation and provides evidence for the role of cytotypic variation and geographic isolation in shaping diversity, differentiation, and potentially speciation in the P. amabilis-P. woodhousei complex.

Phylogenetics of Morus (Moraceae) Inferred from ITS and trnL-trnF Sequence Data

Abstract Morus (Tribe Moreae, Moraceae) consists of ca. 13 species of trees distributed in Asia, Africa, Europe, and North, Central, and South America. The broad geographical distribution of the genus, overlapping ranges of many taxa, and documented hybridization between some species present interesting questions of taxonomy, phylogeny, and biogeography. Phylogenetic data for Morus also contribute to higher level taxonomic work in the family. We used sequence data from ITS of the nrDNA and the chloroplast trnL-trnF intergenic spacer to study phylogenetic relationships of Morus. Phylogenies based on separate data sets were not statistically incongruent, and the combined tree reveals that Morus, as currently circumscribed, is non-monophyletic. Subgenus Morus (sensu Leroy) is resolved as a clade and consists of two well-supported clades: one of Asian taxa and one of North American taxa. Sampled members of the genus Trophis (two, including the type) form a clade sister to subgenus Morus. Morus mesozygia (Africa; subgenus Afromorus) and M. insignis (Neotropics; subgenus Gomphomorus), which have not been included to date in other phylogenetic studies of the family, are placed outside the subgenus Morus-Trophis clade. This work is an important step in elucidating relationships of Morus and along with other recent phylogenetic studies in Moraceae, underscores the need for further work within Tribe Moreae to clarify natural generic relationships.

Development, characterization and transferability of microsatellite markers for the plant genus Phlox (Polemoniaceae)

In order to study diversification and microevolution in Phlox, we developed nine polymorphic microsatellite loci. In 20 individuals of Phlox pilosa from a single population, the average number of alleles per locus was 10.0 ± 5.1, and average observed and expected heterozygosities were 0.611 ± 0.234 and 0.769 ± 0.170, respectively. Most of these markers amplified successfully in 11 additional species of Phlox, representing a broad diversity of the genus, and some also amplified in more distantly related members of the Polemoniaceae. These microsatellite markers will be valuable for investigation of evolutionary processes in this important study system.

The role of polyploidy in shaping morphological diversity in natural populations of Phlox amabilis

PREMISE OF THE STUDY Studies of natural populations of polyploids increasingly highlight complex patterns of variation in ploidy and geographic distribution of cytotypes. As our understanding of the complexity of polyploidy grows, our understanding of the morphological correlates of polyploidy should expand as well. Here we examine in what ways, and to what degree, polyploidy affects the overall phenotype of a species across its distribution when there are three ploidies and geographic complexity in cytotype distribution. METHODS We measured 31 morphological traits from stems, leaves, and flowers from up to 25 individuals from 11 sites across the distribution of Phlox amabilis. Chromosome counts and flow cytometry confirmed and expanded upon earlier research documenting diploid, tetraploid, and hexaploid populations, and also identified a site with two ploidies. Univariate and multivariate statistics were used to characterize the morphological effects of polyploidy. KEY RESULTS We detected significant associations between morphology and ploidy in 11 traits spread across vegetative and reproductive structures. Generally, diploid individuals differed from polyploid individuals to a greater extent, and in different ways, than tetraploid and hexaploid plants differed from each other. Multivariate morphometrics demonstrated that the two primary axes of overall variation are driven by morphological traits associated with polyploidy, and individuals of different ploidies can be discriminated with 95% success. CONCLUSIONS Polyploidy plays a major role in shaping overall morphological diversity in natural populations of P. amabilis.