Conley K. McMullen

Invaders of pollination networks in the Galapagos Islands: emergence of novel communities.

The unique biodiversity of most oceanic archipelagos is currently threatened by the introduction of alien species that can displace native biota, disrupt native ecological interactions, and profoundly affect community structure and stability. We investigated the threat of aliens on pollination networks in the species-rich lowlands of five Galápagos Islands. Twenty per cent of all species (60 plants and 220 pollinators) in the pooled network were aliens, being involved in 38 per cent of the interactions. Most aliens were insects, especially dipterans (36%), hymenopterans (30%) and lepidopterans (14%). These alien insects had more links than either endemic pollinators or non-endemic natives, some even acting as island hubs. Aliens linked mostly to generalized species, increasing nestedness and thus network stability. Moreover, they infiltrated all seven connected modules (determined by geographical and phylogenetic constraints) of the overall network, representing around 30 per cent of species in two of them. An astonishingly high proportion (38%) of connectors, which enhance network cohesiveness, was also alien. Results indicate that the structure of these emergent novel communities might become more resistant to certain type of disturbances (e.g. species loss), while being more vulnerable to others (e.g. spread of a disease). Such notable changes in network structure as invasions progress are expected to have important consequences for native biodiversity maintenance.

Pollination patterns and plant breeding systems in the Galápagos: a review

BACKGROUND Despite the importance of the Galápagos Islands for the development of central concepts in ecology and evolution, the understanding of many ecological processes in this archipelago is still very basic. One such process is pollination, which provides an important service to both plants and their pollinators. The rather modest level of knowledge on this subject has so far limited our predictive power on the consequences of the increasing threat of introduced plants and pollinators to this unique archipelago. SCOPE As a first step toward building a unified view of the state of pollination in the Galápagos, a thorough literature search was conducted on the breeding systems of the archipelagos flora and compiled all documented flower-visitor interactions. Based on 38 studies from the last 100 years, we retrieved 329 unique interactions between 123 flowering plant species (50 endemics, 39 non-endemic natives, 26 introduced and eight of unknown origin) from 41 families and 120 animal species from 13 orders. We discuss the emergent patterns and identify promising research avenues in the field. CONCLUSIONS Although breeding systems are known for <20 % of the flora, most species in our database were self-compatible. Moreover, the incidence of autogamy among endemics, non-endemic natives and alien species did not differ significantly, being high in all groups, which suggests that a poor pollinator fauna does not represent a constraint to the integration of new plant species into the native communities. Most interactions detected (approx. 90 %) come from a single island (most of them from Santa Cruz). Hymenopterans (mainly the endemic carpenter bee Xylocopa darwinii and ants), followed by lepidopterans, were the most important flower visitors. Dipterans were much more important flower visitors in the humid zone than in the dry zone. Bird and lizard pollination has been occasionally reported in the dry zone. Strong biases were detected in the sampling effort dedicated to different islands, time of day, focal plants and functional groups of visitors. Thus, the existing patterns need to be confronted with new and less biased data. The implementation of a community-level approach could greatly increase our understanding of pollination on the islands and our ability to predict the consequences of plant invasions for the natural ecosystems of the Galápagos.

Two new species of Miconia sect. Sagraea (Melastomataceae) from the Macaya Biosphere Reserve, Haiti, and twelve relevant new species combinations

The Sagraea clade (Melastomataceae, tribe Miconieae) is briefly characterized, typified, and formally treated as a section within Miconia. In addition, two new species of Miconia sect. Sagraea, endemic to the floristically diverse Massif de la Hotte of southwestern Haiti and discovered during the course of a systematic revision of the Caribbean species of this section, are here described and illustrated. Miconia hottensis and M. navifolia, morphologically similar and possible sister species, are compared to each other and to the widespread Caribbean species M. capillaris and the southwestern Dominican Republic endemic M. tetraptera; these four species share rectangular stems with four low ridges or wings and minute, short-stalked, peltate or pseudopeltate hairs and likely form a clade.

Nocturnal and diurnal pollination of Clerodendrum molle (Verbenaceae) in the Galápagos Islands

The primary hypothesis of this study was that in the Galápagos Islands, fruit and seed set via nocturnal pollination would exceed that of diurnal pollination because of the greater insect activity at night typical of hot, arid regions. Clerodendrum molle, a widespread member of the Galápagos flora was submitted to pollination experiments, visitor observations, nectar sampling, pollen transfer studies, pollen–ovule ratio studies, and pollen measurements. Flowers set fruit and seed via open pollination, autonomous autogamy, facilitated autogamy, facilitated cross-pollination, diurnal pollination, and nocturnal pollination. Results indicate no significant difference in fruit set. Cross-pollinated flowers showed a significant increase in seed set over all treatments except facilitated autogamy. Nocturnal and diurnal fruit and seed set did not differ significantly. Nocturnal visitors included ants, spiders, hawk moths, and roaches whereas diurnal visitors included carpenter bees and ants. Galápagos members of C. molle exhibit incomplete protandry and set fruit via autonomous autogamy as a result of natural selection in an environment with few faithful pollinators. Overall low fruit and seed set are likely because of a combination of pollen and resource limitation, the latter exacerbated by nectar robbing. Studies of island angiosperms are crucial for complete understanding of the population dynamics of indigenous plants, which can assist conservation officials in protecting these species.

Floral Phenology and Sex Ratio of Piratebush (Buckleya distichophylla), a Rare Dioecious Shrub Endemic to the Southern Appalachian Mountains

ABSTRACT Piratebush (Buckleya distichophylla, Santalaceae) is a rare dioecious and hemiparasitic shrub endemic to the Appalachian Mountains of Virginia, North Carolina, and Tennessee. Previous studies on piratebush suggest sexual reproductive deficiency as a possible explanation for the rare and scattered distribution of piratebush and a concern for subsequent population decline. To further investigate the reproductive biology of piratebush, we examined sex ratio and flowering phenology in the densest population of piratebush, found on Poor Mountain in southwest Virginia. Sex ratio data were collected through field surveys along ecological transects. Results show a male-biased sex ratio (61:39) of flowering individuals, with 15% nonflowering. Size data confirm significantly smaller size for nonflowering individuals (p < 0.01), suggesting combined characteristics of size and nonflowering as an indicator of juvenility. Floral phenology data were recorded from 23 males and 20 females in varied representative elevation and aspect gradients. Flower abundance was male-dominant by >24:1. Floral phenology showed individual variation, with males beginning and ending approximately 1 wk before females, but considerable synchrony for the bulk of flower production for about 2 wk from 4 May to 16 May. Average high and low ground surface temperatures from the site are also reported. The widely male-dominant sex ratio and floral abundance, as well as variation in flower production by females, underscore the importance of ongoing investigations into the reproductive and regenerative health of this rare and scattered species.

Noteworthy Additions to the Vascular Flora of Rockingham County, Virginia

Abstract Rockingham County, located in northwestern Virginia, is the third largest county in the state and is botanically rich and diverse. Over the past few decades, it has experienced unprecedented population growth and the loss of undisturbed habitat that accompanies such growth. This study updates the documented flora of Rockingham County, so that it may serve as a baseline for future studies, as well as provide new plant distribution information for the Flora of Virginia Project. During the course of this study, 425 numbers representing 316 species, subspecies, and varieties were collected. Fifty-two county records are reported. Five of these, Abies balsamea, Alnus incana ssp. rugosa, Calycanthus floridus var. glaucus, Scutellaria incana, and Penstemon hirsutus, are listed on the Virginia Department of Conservation and Recreations (Division of Natural Heritage) Rare Vascular Plant List. Two others, Sanicula trifoliata and Helianthus hirsutus, are currently listed on the Virginia Vascular Plant Watch List.

Floristic Survey of the Vascular Plants of Shenandoah County, Virginia

ABSTRACT The objective of this study was to create a comprehensive list of the vascular plants of Shenandoah County, Virginia. Specimens were collected from the field during the 2011 growing season, from March 21 to October 27, and part of the 2012 growing season, from March 22 to May 30. Local herbaria of James Madison University (JMUH), Bridgewater College (BDWR), Eastern Mennonite University (HAVI) and Lord Fairfax Community College (LFCC) were searched for pre-existing specimens. The results of the study were compared to records of the Digital Atlas of the Virginia Flora, which currently maps the distribution of vascular plants in Virginia. The combined list based on field collections, pre-existing herbarium specimens, and the Digital Atlas comprises a total of 1,296 species in 568 genera and 142 families. Of these, 57 species are ferns and fern allies, 8 are gymnosperms, 911 are dicots, and 320 are monocots. The records represent 1,009 species native to Virginia, 271 introduced, 12 of uncertain native status, and 2 species believed to occur in both native and introduced populations. Of the 271 introduced species, 61 are considered invasive to some degree. Forty-one species are considered rare in Virginia, and one is endangered at the federal level. This survey resulted in 53 county records, 2 of which also represent state records. Voucher specimens of new field collections are housed in JMUH.

Noteworthy Collections: VIRGINIA

Trillium nivale Riddell (TRILLIACEAE)— Rockingham County: Approximately 4.0 km N of Keezletown, off of Mountain Valley Road, at the end of Walnut Hill Drive on forested hillside; 38u26.6509N, 078u46.3179W; elevation ca. 526 m; 30 March 2008. Conley K. McMullen 891 (photo) (JMUH). Significance. This is the first collection of T. nivale (snow trillium) from Rockingham County, and the second report for Virginia. An earlier collection was made near Forks of Waters in Highland County by Charles E. Stevens on 17 April 1983 [Charles E. Stevens 18455 (VPI)]. The specific location listed by Stevens is ‘‘wooded, limestone bluff of South Branch Potomac River ca. 0.15 mi S of where West Virginia line crosses river.’’ Stevens lists the elevation as 2330 ft. Trillium nivale is also found in Pendleton County, West Virginia, which borders both Rockingham and Highland Counties. Although considered rare in West Virginia, it is also listed for the counties of Cabell, Grant, Preston, Randolph, and Tucker (Harmon et al. 2006). The Cabell County record was likely planted and has not been observed since the mid-1970s (Paul J. Harmon pers. comm.). Other states reporting T. nivale include Illinois, Indiana, Iowa, Kentucky, Maryland, Michigan, Minnesota, Missouri, Nebraska, Ohio, Pennsylvania, South Dakota, and Wisconsin (Case 2002). This species is found primarily at the southern edge of Pleistocene glaciation, and tends to prefer areas devoid of humus, leaf litter, and other plants (Case 2002). *email address: mcmullck@jmu.edu Received May 8, 2008; Accepted July 18, 2008.