California Floristic Province Research Articles

Páramo is the world's fastest evolving and coolest biodiversity hotspot

Understanding the processes that cause speciation is a key aim of evolutionary biology. Lineages or biomes that exhibit recent and rapid diversification are ideal model systems for determining these processes. Species rich biomes reported to be of relatively recent origin, i.e., since the beginning of the Miocene, include Mediterranean ecosystems such as the California Floristic Province, oceanic islands such as the Hawaiian archipelago and the Neotropical high elevation ecosystem of the Páramos. Páramos constitute grasslands above the forest tree-line (at elevations of c. 2800–4700 m) with high species endemism. Organisms that occupy this ecosystem are a likely product of unique adaptations to an extreme environment that evolved during the last three to five million years when the Andes reached an altitude that was capable of sustaining this type of vegetation. We compared net diversification rates of lineages in fast evolving biomes using 73 dated molecular phylogenies. Based on our sample, we demonstrate that average net diversification rates of Páramo plant lineages are faster than those of other reportedly fast evolving hotspots and that the faster evolving lineages are more likely to be found in Páramos than the other hotspots. Páramos therefore represent the ideal model system for studying diversification processes. Most of the speciation events that we observed in the Páramos (144 out of 177) occurred during the Pleistocene possibly due to the effects of species range contraction and expansion that may have resulted from the well-documented climatic changes during that period. Understanding these effects will assist with efforts to determine how future climatic changes will impact plant populations.

Phylogenetic treatment and taxonomic revision of the trapdoor spider genus Aptostichus Simon (Araneae,Mygalomorphae, Euctenizidae).

This systematic study documents the taxonomy, diversity, and distribution of 40 species of the predominately Californian trapdoor spider genus Aptostichus Simon, 1891. Thirty-three of these species are newly described: Aptostichus dantrippi, Aptostichus cabrillo, Aptostichus pennjillettei, Aptostichus asmodaeus, Aptostichus nateevansi, Aptostichus chiricahua, Aptostichus icenoglei, Aptostichus isabella, Aptostichus muiri, Aptostichus barackobamai, Aptostichus sinnombre, Aptostichus hedinorum, Aptostichus aguacaliente, Aptostichus chemehuevi, Aptostichus sarlacc, Aptostichus derhamgiulianii, Aptostichus anzaborrego, Aptostichus serrano, Aptostichus mikeradtkei, Aptostichus edwardabbeyi, Aptostichus killerdana, Aptostichus cahuilla, Aptostichus satleri, Aptostichus elisabethae, Aptostichus fornax, Aptostichus lucerne, Aptostichus fisheri, Aptostichus bonoi, Aptostichus cajalco, Aptostichus sierra, Aptostichus huntington, Aptostichus dorothealangeae, and Aptostichus chavezi. Most of these species are restricted to the California Floristic Province, a known biodiversity hotspot. Of the 40 recognized species, over half are considered to be imperiled or vulnerable and two have likely gone extinct over the past half-century; the conservation status of only 11 species is considered to be secure. Using 73 quantitative and qualitative morphological characters I propose a preliminary phylogeny for the genus that recognizes four major lineages: the Atomarius, Simus, Hesperus, and Sierra species groups. Additionally, the phylogenetic analysis indicates that adaptations favoring the invasion of the arid desert habitats of southern California have evolved multiple times across the group. The existence of both desert and non - desert species in three of the four species groups makes this genus an ideal candidate for the study of the evolutionary ecology of desert arthropods. A set of molecular characters based on the contiguous mitochondrial DNA genes 16S-tRNA valine-12S is used in an independent analysis to assist in placement of specimens into species. The taxonomy section explicitly identifies the concept employed in species delimitation. Niche based distribution models are constructed to predict the ranges of species for which an adequate number of sampling sites were known.

Jeffrey Pine Seed Dispersal in the Sierra San Pedro Mártir, Baja California, Mexico

The Sierra San Pedro Mártir (SSPM) in northern Baja California, Mexico, is a remote mountain at the southern edge of the California Floristic Province, a vegetation type that includes the Sierra Nevada of California and western Nevada. Unlike most forests in the southwestern United States, the forests of the SSFM have never been logged and have experienced only light grazing in recent years, and wildfires have not been suppressed until recent decades. The SSFM represents one of the best examples of an intact presettlement forest in the California Floristic Province. We investigated the mode of seed dispersal of Jeffrey pine (Pinus jeffreyi) in the SSPM, and compared it to that from the eastern slope of the Sierra Nevada, to determine how this process might differ between nearly pristine and heavily altered forests. We found that seed dispersal appears to occur by the same means in both forests (i.e., scatter hoarding of seeds by rodents), but that seedling establishment is much less successful in the SSPM. We considered several hypotheses for why this difference might exist, including the size of seed crops, fire regimes, climate change, grazing by domestic ungulates, and lack of facilitation by shrubs (i.e., nurse plants), but none of these explanations appears adequate to account for the difference. Instead, we suggest that the slow rate of seedling establishment at the SSPM is due to a greater consumption of seeds cached by California chipmunks (Tamias obscurus), who experience a relatively long period of euthermic winter activity in the warm climate of the SSPM. This greater consumption leaves few seeds to germinate. Future studies should test the relative importance of these alternative causes for low seedling recruitment at the SSPM.

Modeling plant species distributions under future climates: how fine scale do climate projections need to be?

Recent studies suggest that species distribution models (SDMs) based on fine-scale climate data may provide markedly different estimates of climate-change impacts than coarse-scale models. However, these studies disagree in their conclusions of how scale influences projected species distributions. In rugged terrain, coarse-scale climate grids may not capture topographically controlled climate variation at the scale that constitutes microhabitat or refugia for some species. Although finer scale data are therefore considered to better reflect climatic conditions experienced by species, there have been few formal analyses of how modeled distributions differ with scale. We modeled distributions for 52 plant species endemic to the California Floristic Province of different life forms and range sizes under recent and future climate across a 2000-fold range of spatial scales (0.008-16km(2) ). We produced unique current and future climate datasets by separately downscaling 4 km climate models to three finer resolutions based on 800, 270, and 90m digital elevation models and deriving bioclimatic predictors from them. As climate-data resolution became coarser, SDMs predicted larger habitat area with diminishing spatial congruence between fine- and coarse-scale predictions. These trends were most pronounced at the coarsest resolutions and depended on climate scenario and species' range size. On average, SDMs projected onto 4 km climate data predicted 42% more stable habitat (the amount of spatial overlap between predicted current and future climatically suitable habitat) compared with 800m data. We found only modest agreement between areas predicted to be stable by 90 m models generalized to 4 km grids compared with areas classified as stable based on 4km models, suggesting that some climate refugia captured at finer scales may be missed using coarser scale data. These differences in projected locations of habitat change may have more serious implications than net habitat area when predictive maps form the basis of conservation decision making.

Testing the species limits of the tarantulas (Araneae: Theraphosidae) endemic to California's Southern Coast Ranges, USA

Abstract The California floristic province is home to several threatened or endangered species and has been the focus of numerous conservation efforts. These conservation efforts have largely ignored the diverse and distinctive arthropod fauna found in this region. We investigate the species boundaries of the four tarantula (Araneae: Theraphosidae) species endemic to California's Southern Coast Ranges through molecular phylogenetic analysis using a 680 bp region of the mitochondrial gene cytochrome oxidase subunit 1 from 51 individuals. Our analysis resulted in a well‐supported phylogeny showing three distinct clades. As a result, we recognise only one species in the Southern Coast Ranges (Aphonopelma brunnius, with A. chamberlini and A. smithi treated as junior synonyms; if the holotype of A. rileyi is located it will likely be a synonym as well). Two additional species were found in the foothills of the Sierra Nevada. Although the tarantulas in California's Southern Coast Ranges are not as endemic as was previously thought, their position as top arthropod predators make them ideal sentinel species, suggesting they should be targeted by conservationists. Furthermore, our analyses illustrate the importance in using molecular tools to investigate biodiversity.

Niche evolution across spatial scales: climate and habitat specialization in California Lasthenia (Asteraceae)

Ecologists and evolutionary biologists perceive the ecological niche as a multidimensional relationship between an organism and its environment. Yet, we know little about the degree to which multiple niche axes evolve in concert across various spatial scales to explain differences in distribution patterns and habitat specialization among lineages. Here we used contemporary phylogenetic approaches to analyze the evolution of species' distributions across multiple spatial scales in Lasthenia, a young and ecologically diverse plant clade largely occurring within the California Floristic Province, USA. Lasthenia species and subspecies range from widely distributed taxa that occupy a diversity of habitat types to locally restricted habitat endemics, including several lineages that are strongly associated with isolated ephemeral wetlands called vernal pools. We quantified the niche of Lasthenia species and subspecies at three different spatial scales: the range‐wide climate niche, the habitat niche, and the within‐habitat depth niche for those taxa occupying vernal pools. We incorporated phylogenetic uncertainty into our analyses by reanalyzing previously described DNA sequences in a Bayesian context and conducting all subsequent comparative analyses over the resulting posterior distribution of ultrametric phylogenetic trees. Using a biogeographic approach for ancestral habitat reconstruction, we estimated that Lasthenia lineages have undergone up to four independent transitions from strictly terrestrial habitats to a niche that incorporates semiaquatic habitats, and one of these transitions led to the subsequent proliferation of vernal pool species and subspecies. We found that the local niche axis, corresponding to the depth distribution of taxa within pools, was more phylogenetically conserved than the large‐scale axes representing climatic associations. Furthermore, we did not find evidence that niche breadth estimates along different axes were consistently correlated, indicating that ecological specialization may be specific to certain niche axes rather than an overall characteristic of a species.

Historical and Ecological Controls on Phylogenetic Diversity in Californian Plant Communities

We addressed the classic question of whether community diversity is determined from the bottom up by the breadth and partitioning of niche space or from the top down by historical and evolutionary forces. Specifically, we contrasted local and regional explanations for the diversity of Californian plant communities using phylogenetic and functional analyses. Our communities were sets of four field plots that sampled alpha (within-plot) and beta (among-plot) sources of variation in diversity. We sampled 93 such communities nested within 78 larger regions for which regional species pools could be independently estimated, spanning the California Floristic Province. We measured phylogenetic and functional diversity within plots and between plots on neighboring soils and slopes. We also measured the phylogenetic diversity of regional species pools and analyzed them in terms of biogeographic groups. We found no evidence linking the phylogenetic diversity of communities to within-plot functional diversity or among-plot beta diversity. Instead, we found that the phylogenetic diversity of communities depends on that of regional species pools. In turn, phylogenetically diverse pools were those with high proportions of species of northern biogeographic affinity, which have relatively mesic distributions and traits. This supports what we call the climatic refuge hypothesis rather than the biogeographic crossroads hypothesis.

Phylogeny, biogeography, and chromosome evolution of the amphitropical genus Grindelia (Asteraceae) inferred from nuclear ribosomal and chloroplast sequence data

AbstractGrindelia is among the most taxonomically challenging groups of North American composites. The genus as a whole has an amphitropical distribution, with approximately half of the species native to North America and Mexico and the remainder native to South America. We used DNA sequence data from the nuclear ribosomal ITS and ETS and chloroplast psaI‐accD regions to revisit hypotheses on biogeographic history across the genus. Grindelia as a whole is well‐supported and is composed of two sister clades, one native to South America and the other native to North America including Mexico. The North American taxa constitute two clades that largely occur on different sides of the Continental Divide. The diverse radiation of Grindelia in the California Floristic Province appears to be most closely related to species from the Great Basin and Colorado Plateau and evidently descended from drought‐adapted ancestors. Although Steyermark's hypotheses about the relationships of North American Grindelia are not all supported, we did recover a clade corresponding to his Pacific radiation and many of the Mexican and Texan species that he hypothesized to be basal in the genus represent early diverging lineages in our trees. Dunford's cytogenetic data on the North American species of Grindelia were also examined in a phylogenetic context.

Evaluation of assisted colonization strategies under global change for a rare, fire‐dependent plant

AbstractAs a clear consensus is emerging that habitat for many species will dramatically reduce or shift with climate change, attention is turning to adaptation strategies to address these impacts. Assisted colonization is one such strategy that has been predominantly discussed in terms of the costs of introducing potential competitors into new communities and the benefits of reducing extinction risk. However, the success or failure of assisted colonization will depend on a range of population‐level factors that have not yet been quantitatively evaluated – the quality of the recipient habitat, the number and life stages of translocated individuals, the establishment of translocated individuals in their new habitat and whether the recipient habitat is subject to ongoing threats all will play an important role in population persistence. In this article, we do not take one side or the other in the debate over whether assisted colonization is worthwhile. Rather, we focus on the likelihood that assisted colonization will promote population persistence in the face of climate‐induced distribution changes and altered fire regimes for a rare endemic species. We link a population model with species distribution models to investigate expected changes in populations with climate change, the impact of altered fire regimes on population persistence and how much assisted colonization is necessary to minimize risk of decline in populations of Tecate cypress, a rare endemic tree in the California Floristic Province, a biodiversity hotspot. We show that assisted colonization may be a risk‐minimizing adaptation strategy when there are large source populations that are declining dramatically due to habitat contractions, multiple nearby sites predicted to contain suitable habitat, minimal natural dispersal, high rates of establishment of translocated populations and the absence of nonclimatic threats such as altered disturbance regimes. However, when serious ongoing threats exist, assisted colonization is ineffective.

Fungal endophyte–grass symbioses are rare in the California floristic province and other regions with Mediterranean-influenced climates

Abstract Research on agronomic grasses has shown that Class 1 fungal endophytes ( Neotyphodium/Epichloe ; Clavicipitaceae) can have profound effects on host plant fitness. However, in natural systems, even basic ecological knowledge of most endophyte symbioses is lacking. Here, I describe the distribution and abundance of endophytes across 36 native (or naturalized) grasses in a previously unsurveyed region, the California Floristic Province. Symbiosis was generally low: 8.33 % of species and 18.75 % of genera hosted endophytes. I then compared the proportions of symbiotic species and genera found in California and other Mediterranean regions to the proportions found in non-Mediterranean regions. Surveys of Mediterranean-influenced regions showed significantly lower proportions of species (∼66 % lower) and genera (∼65 % lower) hosting endophyte than surveys of non-Mediterranean regions. This pattern suggests that selection in Mediterranean climates may not favor endophyte symbioses.

Diversification ofCeanothus(Rhamnaceae) in the California Floristic Province

High diversity and endemism in the California Floristic Province (CFP) are an alleged response to the late Cenozoic advent of Mediterranean-type climate in this region. Ceanothus comprises two divergent subgenera with centers of diversity in the CFP. We reconstruct the evolution of Ceanothus by using DNA sequence data from the nuclear gene nitrate reductase. We find that the timing of diversification events is related to geological and climatic history. In both subgenera, diversification is characterized by recent divergence of extant taxa and geographically structured phylogenetic relationships. A strong north-south divergence of subgenus Cerastes across the Transverse Ranges indicates that phylogenetic relationships may be structured by climatically divergent regions of the CFP. Divergence-time estimation suggests that the age of extant diversification in both subgenera is ∼6 Ma. This agrees with the fossil record but predates the hypothesized Quaternary (2-Ma) origin of Mediterranean-type climate in the region.

Pollinator‐mediated gene flow fosters genetic variability in a narrow alpine endemic, Abronia alpina (Nyctaginaceae)

For rare and endemic plants that exist in small, isolated habitats, natural selection is expected to favor self-compatibility, which can result in low genetic diversity due to inbreeding and genetic drift. Using Abronia alpina, a rare alpine endemic of the California Floristic Province, we demonstrate that there are exceptions to these predictions. We present the results of both a pollination experiment and a genetic study using AFLPs (amplified fragment length polymorphisms). Using controlled hand-pollination and pollinator observations, we examined the breeding system, pollination ecology, and mechanism for self-incompatibility in A. alpina. Abronia alpina exhibits an allogamous mating system with probable self-incompatibility resulting from limited growth of pollen tubes originating from self-pollination. Only xenogamous crosses and open-pollinated controls produced seed, and only xenogamous crosses produced pollen tubes that reached the ovary. The molecular study shows that A. alpina has substantial genetic diversity for a rare, endemic species, evidenced by the high percentage of polymorphic loci and average expected heterozygosity. Gene flow among subpopulations, as inferred from AFLP markers, appears to be substantial, although the Kern River is an important physical barrier. Our results indicate that A. alpina is dependent on insects for both seed production and the maintenance of genetic diversity. This finding suggests that pollinators may be crucial to the long-term adaptive potential of rare, endemic plants and that conservation of rare endemics is, in part, dependent on community-level interactions such as plant-pollinator mutualisms.

Inferring Species Trees from Gene Trees in a Radiation of California Trapdoor Spiders (Araneae, Antrodiaetidae, Aliatypus)

BackgroundThe California Floristic Province is a biodiversity hotspot, reflecting a complex geologic history, strong selective gradients, and a heterogeneous landscape. These factors have led to high endemic diversity across many lifeforms within this region, including the richest diversity of mygalomorph spiders (tarantulas, trapdoor spiders, and kin) in North America. The trapdoor spider genus Aliatypus encompasses twelve described species, eleven of which are endemic to California. Several Aliatypus species show disjunct distributional patterns in California (some are found on both sides of the vast Central Valley), and the genus as a whole occupies an impressive variety of habitats.Methodology/Principal FindingsWe collected specimens from 89 populations representing all described species. DNA sequence data were collected from seven gene regions, including two newly developed for spider systematics. Bayesian inference (in individual gene tree and species tree approaches) recovered a general “3 clade” structure for the genus (A. gulosus, californicus group, erebus group), with three other phylogenetically isolated species differing slightly in position across different phylogenetic analyses. Because of extremely high intraspecific divergences in mitochondrial COI sequences, the relatively slowly evolving 28S rRNA gene was found to be more useful than mitochondrial data for identification of morphologically indistinguishable immatures. For multiple species spanning the Central Valley, explicit hypothesis testing suggests a lack of monophyly for regional populations (e.g., western Coast Range populations). Phylogenetic evidence clearly shows that syntopy is restricted to distant phylogenetic relatives, consistent with ecological niche conservatism.Conclusions/SignificanceThis study provides fundamental insight into a radiation of trapdoor spiders found in the biodiversity hotspot of California. Species relationships are clarified and undescribed lineages are discovered, with more geographic sampling likely to lead to additional species diversity. These dispersal-limited taxa provide novel insight into the biogeography and Earth history processes of California.

Relationships in the Lupinus albifrons Species Complex (Fabaceae) based on Two Highly Variable Chloroplast Regions

Abstract The perennial lupines of western North America, previously suggested to be monophyletic, comprise an apparently rapid and recent species radiation concentrated in the California Floristic Province. The Lupinus albifrons species complex consists of a number of closely related yet morphologically variable taxa within the larger group of perennial lupines. We used sequence data from two rapidly evolving noncoding chloroplast regions to analyze relationships in the perennial lupines, with special emphasis on the Lupinus albifrons species complex. Sampling from throughout the ranges of species thought to be closely related to Lupinus albifrons, we found that this group is characterized by high genetic diversity not only between species, but also within species and even within populations. The results of this study call into question the monophyly of the western North American perennials. Only two taxa clearly emerge as deserving recognition at the species or subspecies level based on the molecular dat...

Systematics, Phylogeny, and Evolution of Papaver californicum and Stylomecon heterophylla (Papaveraceae)

We present a detailed comparison of Papaver californicum and Stylomecon heterophylla, which earlier were found to be sister species and most closely related to Meconopsis cambrica Papaver s.str. from western Eurasia. The two species of winter annuals differ mainly in the shape of their distal cauline leaves, coloration of petals and staminal filaments, and most notably morphology of the gynoecium and capsule, with Papaver californicum having a sessile stigmatic disc and Stylomecon heterophylla having a distinct style. They were earlier found to differ in ploidy, with chromosome numbers of 2n = 28 (Papaver californicum) and 2n = 56 (Stylomecon heterophylla). Mapped distributions of the two species indicate that the range of S. heterophylla encompasses and exceeds that of P. californicum; both are known only from the California Floristic Province except for one collection of S. heterophylla from central Baja California. Whereas Papaver californicum is most commonly found in burn localities in the first wet season after fire, Stylomecon heterophylla is active under a broader range of environmenal conditions and often occurs in habitats that appear to be somewhat more mesic. Both species are self-compatible and autonomously self-pollinating. Experimental hybridization resulted in well-developed but entirely sterile hybrids; no hybrids are known from nature. Based on these and earlier findings, we conclude that Stylomecon heterophylla is best treated in Papaver, as P. heterophyllum.

Plants of the Colonet Region, Baja California, Mexico, and a Vegetation Map of Colonet Mesa

The Colonet region is located at the southern end of the California Floristic Province, in an area known to have the highest plant diversity in Baja California. A preliminary list of vouchered specimens is developed for the area, and a vegetation map for Colonet Mesa is presented. The Colonet region has at least 435 vascular plant taxa, of which 383 are native to Baja California, and 52 are endemic or nearly endemic. This list includes five local endemic taxa known only from the Colonet region, 18 taxa on the California Native Plant Society List 1B of taxa that are "rare, threatened, or endangered in California and elsewhere," and three on the Mexican NOM 059 list of protected taxa. The Mexican federal government has proposed to build a major port and a new city at Colonet. To understand the potential impact of the port on the regional biodiversity, we examine three areas---a Footprint area which will presumably be highly affected by the port, the Mesa area which contains all the known vernal pools, and a Buffer area surrounding the other two areas. The large Buffer shows the greatest number of native and endemic taxa, followed by the Mesa. The Footprint has two species of high conservation concern that are not represented elsewhere in the study area. The vegetation map of Colonet Mesa confirms the presence of large vernal pools and shows extensive maritime chaparral, neither of which has been reported from elsewhere in northwest Baja California. This report documents the high plant biodiversity of the region and highlights the rare and unique species and vegetation types of Colonet Mesa.

Range edges and the molecular divergence of Greya moth populations

Aim We investigated the geographical pattern of genetic divergence and demographic history in the prodoxid moth Greya obscura throughout its entire geographical range in far western North America and compared it to the geographical patterns found in a previously studied species, Greya politella, which co-occurs over the same range, in the same habitats, and on the same host plants. Location The study included sites distributed throughout the California Floristic Province. Methods We used analysis of cytochrome c oxidase subunit I (COI) and amplified fragment length polymorphisms to evaluate the pattern and history of genetic continuity among populations. Results Greya obscura populations show a history of spatial expansion with considerable haplotype diversity in the centre of the geographical range. As with G. politella, some range-edge populations of G. obscura are sufficiently divergent (6.7% in COI) to be considered as potentially cryptic species. Greya obscura and G. politella, however, differ in the specific range-edge sites showing greatest genetic divergence and cryptic speciation. Main conclusions These results corroborate the view that range edges are important cradles of divergence and speciation. In addition, the results indicate that the geographical pattern of divergence at edges may differ even among closely related species occupying the same habitats and using the same hosts.

The Succulent Scrub of San Martín Island, Baja California, Mexico

Baja California, Mexico, is home to enormous floristic diversity (Rieman & Ezcurra 2005; Peinado et al. 1995; Wiggins 1980) including a wealth of cacti and succulents. Readers may have accompanied CSSA trips to Baja California or may have read articles about the plants seen on those trips. On the Pacific Coast, near the southern edge of the California Floristic Province (which California shares with Oregon and Baja California), lies Greater San Quintin, a diverse and relatively unspoiled region (Howell 1957; Thorne 1993). The area includes eleven extinct volcanic cones with elevations up to 260 m, one of which is the island of San Martin that lies 5 km (3 mi) off shore. Island floras are of particular interest to botanists due to their isolation from mainland source populations which, in the context of variation in dispersal abilities among plant groups, results in unique plant communities (Carlquist 1974). San Martin Island is the southernmost of the Pacific Channel Islands on the continental shelf; it is also amongst the smallest, being only 0.9 square mile (2.3 square kilometers) in area ( Junak & Philbrick 1994). San Martin is unusual never having had large introduced animals such as goats and pigs, which have seriously impacted most of the California Channel Islands at some point in their history. Thus despite the small size of San Martin Island, it remains home to several endemic vertebrates (Samaniego-Herrera 2007). Although rabbits and cats were reported on the Island historically, today the largest non-native inhabitants are a few chickens that forage in the area around the fishing camp. San Martin Island is a cindercone, mostly composed of sharp volcanic lava rock, often with a dense covering of foliose lichens. There is relatively little soil buildup across most of the island, and the plants of the succulent maritime scrub grow among the rocks. There are also small areas

Elucidating the phylogeographic structure among a mosaic of unisexual and bisexual populations of the weevil Geodercodes latipennis (Coleoptera: Curculionidae) in the Transverse Ranges of southern California

Studies investigating the short-term benefits of asexual reproduction suggest that there are a variety of ecological and genetic factors that influence relative success rates. The current study focuses on investigating these factors in the weevil Geodercodes latipennis with newly discovered parthenogenetic populations in the California Floristic Province. Phylogenetic analysis of mitochondrial and nuclear sequence data revealed three independent transitions from sexual to asexual reproduction. One of these asexual lineages had a much broader range than the other sexual and asexual populations, and was distributed across several geographic features that have been implicated as strong phylogeographic barriers in other species in the region, suggesting high migration rates, high adaptability, or both. The success of this lineage relative to the other parthenogenetic clades may be related to its age; however, there were several possibilities explaining why it was more broadly distributed than its sexual sister group. Understanding how various factors operate in one system contributes to our understanding of how the evolutionary history of lineages with frequent transitions to parthenogenesis can be affected by the short-term advantages of asexual reproduction. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 101, 935–948.

Isolation of microsatellite loci from endangered members of Lotus (Fabaceae) subgenus Syrmatium

Lotus subgenus Syrmatium is a group of 11 plant species that exhibit extensive ecological and morphological diversity throughout the California floristic province. Fifteen polymorphic microsatellite loci were isolated from two taxa, Lotus argophyllus var. adsurgens and L. dendroideus var. traskiae, and were screened for variability in 15 additional taxa within Lotus subgenus Syrmatium. Moderate levels of variability were observed with mean numbers of alleles per locus ranging from 1.3 to 7.3. The mean observed and expected heterozygosities ranged from 0.09 to 0.47 and 0.10 to 0.79, respectively. These new loci will be useful in conservation genetic and evolutionary studies within Lotus subgenus Syrmatium.