Paul M. Beardsley

RAPID EVOLUTION OF AN INVASIVE PLANT

Exotic plants often face different conditions from those experienced where they are native. The general issue of how exotics respond to unfamiliar environments within their new range is not well understood. Phenotypic plasticity has historically been seen as the primary mechanism enabling exotics to colonize large, environmentally diverse areas. However, new work indicates that exotics can evolve quickly, suggesting that contemporary evolution may be more important in invasion ecology than previously appreciated. To determine the influence of contemporary evolution, phenotypic plasticity, and founder ef- fects in affecting phenotypic variation among introduced plants, we compared the size, fecundity, and leaf area of St. Johns wort ( Hypericum perforatum) collected from native European and introduced western and central North American populations in common gardens in Washington, California, Spain, and Sweden. We also determined genetic rela- tionships among these plants by examining variation in amplified fragment length poly- morphism (AFLP) markers. There was substantial genetic variation among introduced populations and evidence for multiple introductions of H. perforatum into North America. Across common gardens in- troduced plants were neither universally larger nor more fecund than natives. However, within common gardens, both introduced and native populations exhibited significant lat- itudinally based clines in size and fecundity. Clines among introduced populations broadly converged with those among native populations. Introduced and native plants originating from northern latitudes generally outperformed those originating from southern latitudes when grown in northern latitude gardens of Washington and Sweden. Conversely, plants from southern latitudes performed best in southern gardens in Spain and California. Clinal patterns in leaf area, however, did not change between gardens; European and central North American plants from northern latitudes had larger leaves than plants from southern latitudes within these regions in both Washington and California, the two gardens where this trait was measured. Introduced plants did not always occur at similar latitudes as their most closely related native progenitor, indicating that pre-adaptation (i.e., climate matching) is unlikely to be the sole explanation for clinal patterns among introduced populations. Instead, results suggest that introduced plants are evolving adaptations to broad-scale environmental conditions in their introduced range.

AFLP PHYLOGENY OF MIMULUS SECTION ERYTHRANTHE AND THE EVOLUTION OF HUMMINGBIRD POLLINATION

Abstract.— Species in Mimulus section Erythranthe (monkeyflowers) have become model systems for the study of the genetic basis of ecological adaptations. In this study, we pursued two goals. First, we reconstructed the phylogeny of species in Erythranthe using both DNA sequences from the ribosomal DNA ITS and ETS and AFLPs. Data from rDNA sequences support the monophyly of the section, including M. parishii, but provide little support for relationships within it. Analyses using AFLP data resulted in a well‐supported hypothesis of relationships among all Erythranthe species. Our second goal was to reconstruct ancestral pollination syndromes and ancestral states of individual characters associated with hummingbird‐pollinated flowers. Both parsimony and likelihood approaches indicate that hummingbird pollination evolved twice in Erythranthe from insect‐pollinated ancestors. Our reconstruction of individual characters indicates that corolla color and some aspects of corolla shape change states at the same point on the phylogenetic tree as the switch to hummingbird pollination; however, a switch to secretion of high amounts of nectar does not. Floral trait transformation may have been more punctuational than gradual.

Redefining Phrymaceae: the placement of Mimulus, tribe Mimuleae, and Phryma.

Chloroplast trnL/F and nuclear ribosomal ITS and ETS sequence data were used to analyze phylogenetic relationships among members of tribe Mimuleae (Scrophulariaceae) and other closely related families in Lamiales. The results of these analyses led to the following conclusions. (1) The Australian genera Glossostigma and Peplidium and the taxonomically isolated Phryma join four genera of tribe Mimuleae to form a well-supported clade that is distinct from other families in the Lamiales. We refer to that clade as the subfamily Phrymoideae. (2) The genera Mazus and Lancea (tribe Mimuleae) together form a well-supported clade that we recognize as the subfamily Mazoideae. Mazoideae is weakly supported as sister to Phrymoideae. We assign Mazoideae and Phrymoideae to a redefined family Phrymaceae. (3) Mimulus is not monophyletic, because members of at least six other genera have been derived from within it. In light of the molecular evidence, it is clear that species of Phrymaceae (about 190 species) have undergone two geographically distinct radiations; one in western North America (about 130 species) and another in Australia (about 30 species). Phylogenetic interpretations of morphological evolution and biogeographical patterns are discussed.

Patterns of evolution in western North American Mimulus (Phrymaceae).

A well-supported phylogeny is presented from both chloroplast DNA (the trnL/F region) and two regions of nuclear rDNA (ITS [internal transcribed spacer] and ETS [external transcribed spacer]) with nearly complete sampling for Mimulus (Phrymaceae) in western North America. Three separate genera are derived from within the clade that contains all the Mimulus species in western North America. The taxonomic status of the proposed sections of Mimulus and the relationships of many taxonomically difficult species are considered with observations on morphological evolution. Discordance between data sources provides support for the hypothesis that M. evanescens is a hybrid between M. latidens and M. breviflorus. In two major clades (Eunanus and Diplacus), patterns of genetic variation do not match the current taxonomy. The clustering of taxa in Eunanus is strongly associated with geographic distributions. Mimulus aurantiacus sensu Thompson, M. nanus, and M. floribundus are found to be progenitor species to other species that appear to be derived from within them. Polyploidy and aneuploidy events are clustered near the tips of the phylogeny. Thus, these two mechanisms are concluded to have played a relatively small role in the evolution of persistent lineages in Mimulus. The phylogenetic distribution of rare taxa is also examined.

Review of the systematics of Scrophulariaceae s.l. and their current disposition

Recent molecular phylogenetic studies in Lamiales have shown that the large group traditionally recognised as Scrophulariaceae is not monophyletic. Efforts to reconstruct the phylogeny of this large clade and to revise its classification to reflect that phylogeny have resulted in seven monophyletic groups, comprised mostly of members of Scrophulariaceae s.l., recognised as families in recent angiosperm classifications. These are Scrophulariaceae s.s., Orobanchaceae, Veronicaceae (cf. Plantaginaceae), Phrymaceae, Calceolariaceae, Linderniaceae, and Stilbaceae. Sampling completeness at the genus level varies from group to group, but is quite good for many. A few individual genera formerly assigned to Scrophulariaceae do not fit into any existing clade recognised at family rank and are left, at present, unassigned to family. In addition to the recognition of several clades comprised primarily of former members of Scrophulariaceae s.l., several groups previously recognised as families are now included within some of these clades. For example, Scrophulariaceae s.s. includes Buddlejaceae and Myoporaceae, and Veronicaceae includes Callitrichaceae, Globulariaceae, Hippuridaceae, and Plantaginaceae. The clades now recognised as families often are not easily diagnosed, but in many cases are more consistent with certain functional traits and geographical patterns. Examples include Orobanchaceae, which comprises all of the parasitic plants (hemiparasites and holoparasites) and Scrophulariaceae s.s., which is predominantly a southern hemisphere group.

Evolution of biogeographic disjunction between eastern Asia and eastern North America in Phryma (Phrymaceae).

This study examines molecular and morphological differentiation in Phryma L., which has only one species with a well-known classic intercontinental disjunct distribution between eastern Asia (EA) and eastern North America (ENA). Phylogenetic analysis of nuclear ribosomal ITS and chloroplast rps16 and trnL-F sequences revealed two highly distinct clades corresponding to EA and ENA. The divergence time between the intercontinental populations was estimated to be 3.68 ± 2.25 to 5.23 ± 1.37 million years ago (mya) based on combined chloroplast data using Bayesian and penalized likelihood methods. Phylogeographic and dispersal-vicariance (DIVA) analysis suggest a North American origin of Phryma and its migration into EA via the Bering land bridge. Multivariate analysis based on 23 quantitative morphological characters detected no geographic groups at the intercontinental level. The intercontinental populations of Phryma thus show distinct molecular divergence with little morphological differentiation. The discordance of the molecular and morphological patterns may be explained by morphological stasis due to ecological similarity in both continents. The divergence of Phryma from its close relatives in the Phrymaceae was estimated to be at least 32.32 ± 4.46 to 49.35 ± 3.18 mya.

CHROMOSOMAL REARRANGEMENTS AND THE GENETICS OF REPRODUCTIVE BARRIERS IN MIMULUS (MONKEY FLOWERS)

Chromosomal rearrangements may directly cause hybrid sterility and can facilitate speciation by preserving local adaptation in the face of gene flow. We used comparative linkage mapping with shared gene‐based markers to identify potential chromosomal rearrangements between the sister monkeyflowers Mimulus lewisii and Mimulus cardinalis, which are textbook examples of ecological speciation. We then remapped quantitative trait loci (QTLs) for floral traits and flowering time (premating isolation) and hybrid sterility (postzygotic isolation). We identified three major regions of recombination suppression in the M. lewisii × M. cardinalis hybrid map compared to a relatively collinear Mimulus parishii × M. lewisii map, consistent with a reciprocal translocation and two inversions specific to M. cardinalis. These inferences were supported by targeted intraspecific mapping, which also implied a M. lewisii‐specific reciprocal translocation causing chromosomal pseudo‐linkage in both hybrid mapping populations. Floral QTLs mapped in this study, along with previously mapped adaptive QTLs, were clustered in putatively rearranged regions. All QTLs for male sterility, including two underdominant loci, mapped to regions of recombination suppression. We argue that chromosomal rearrangements may have played an important role in generating and consolidating barriers to gene flow as natural selection drove the dramatic ecological and morphological divergence of these species.

Middle School Student Learning in Evolution: Are Current Standards Achievable?

he designation of reasonable and sound academic standards is often touted as the cornerstone upon which science education reform rests (National Academy of Sciences, 1998; Alles, 2001). Given their importance, it is vital that standards be written so that the outlined goals are practically attainable, especially if they are used to design state tests. Therefore, standards for each grade level should be written to coincide with results from the educational literature (Linn et al., 1994).

The Mimulus moschatus Alliance (Phrymaceae): Molecular and Morphological Phylogenetics and their Conservation Implications

Abstract The Mimulus moschatus alliance consists of 13 morphologically similar species, the majority of which have been considered for conservation protection. Phylogenetic analyses of four rapidly evolving molecular DNA regions (ITS, ETS, trnL-F, and rpl16) and a morphological data set under several optimality criteria reveal that the M. moschatus alliance is composed of three geographically defined clades: the Sierra Nevada Clade (M. floribundus, M. norrisii, and M. dudleyi), the Snake River Clade (M. hymenophyllus, M. ampliatus, and M. patulus), and the Columbia River Clade (M. washingtonensis and M. jungermannioides). The relationships within and among the clades are well resolved. Numerous instances of morphological homoplasy among the clades are inferred, including three independent origins of the autogamous mating system. Although nearly half of the morphological characters are highly homoplasious, the inclusion of morphological data in the combined maximum parsimony and Bayesian analyses improves topological resolution and branch support. The phylogenetic results support the specific recognition of three rare taxa (M. ampliatus, M. patulus, and M. dudleyi), previously synonymized with more widespread species. A key to the species within the M. moschatus alliance is provided.

Patterns of evolution in Australian Mimulus and related genera (Phrymaceae~Scrophulariaceae): a molecular phylogeny using chloroplast and nuclear sequence data

The aim of this work was to develop rigorous phylogenetic hypotheses for the mostly Australian species of Mimulus, Glossostigma, Peplidium, Microcarpaea and Elacholoma (Phrymaceae sensu Beardsley and Olmstead 2002), and to use the phylogeny to explore morphological patterns of evolution. Chloroplast trnL/F and nuclear ribosomal internal and external transcribed spacer sequence data were used to analyse phylogenetic relationships. The results of these analyses confirmed the following conclusions proposed in previous morphological analyses: (1) Glossostigma and Peplidium are supported as monophyletic groups, although support is weak for Peplidium; (2) Australian endemic Elacholoma, in the past of uncertain family placement, is embedded within the same clade as the former two genera despite its unique pair of terete stigmatic lobes; (3) a relatively recent dispersal event from Australia to Iraq and the Middle East for P. maritimum is inferred; (4) a reduction in stamen number from four to two has evolved independently several times in Glossostigma, Peplidium, Microcarpaea and Elacholoma; (5) a switch to an obligately autogamous breeding system has evolved several times independently in the group. New findings include the following: (1) Glossostigma, Peplidium, Microcarpaea and Elacholoma are derived from within Mimulus; (2) Mimulus prostratus is part of a clade that contains Elacholoma and Glossostigma, and this clade is not a part of the same clades as other Mimulus species in Australia; (3) there is some support for Microcarpaea being sister to a clade including Elacholoma, Mimulus prostratus, Glossostigma and Peplidium. The discovery that four mostly Australian genera are derived from within the mostly western North American genus Mimulus has important implications for generic assignments. Phylogenetic interpretations of additional morphological character transformations are discussed.