Surface water and ground-water thresholds for maintaining Populus-Salix forests, San Pedro River, Arizona

Ground-water and surface flow depletions are altering riparian ecosystems throughout the southwestern United States, and have contributed to the decline of forests of the pioneer trees Populus fremontii (Fremont cottonwood) and Salix gooddingii (Goodding willow). On some rivers, these forests have been replaced by shrublands of Tamarix ramosissima (tamarisk), a drought-tolerant species from Eurasia. The physiological response of these three riparian plant species to decreases in water availability is well studied, but little attention has been given to shifts in community and population structure in response to declines in surface flow and ground-water levels. Based on study of 17 sites spanning a hydrologic gradient, this research identified hydrologic thresholds above which P. fremontii-S. gooddingii maintain tall dense stands with diverse age classes, and above which they are more abundant than T. ramosissima stands along the San Pedro River in Arizona. Surface flow permanence was the hydrologic variable that explained most of the variance in species abundance and relative importance, with inter-annual ground-water fluctuation and depth to ground water also contributing. P. fremontii and S. gooddingii were dominant over T. ramosissima at sites where surface flow was present more than 76% of the time, inter-annual ground-water fluctuation was less than 0.5 m, and average maximum depth to ground water was less than 2.6 m, during a two-year period of data collection. Because T. ramosissima is a shrub species with smaller leaves and lower canopy heights than P. fremontii and S. gooddingii, these shifts in species composition corresponded to decreases in maximum canopy height and upper stratum (above 8 m) vegetation volume as site water availability declined. As well, sites with deeper water tables and more intermittent flows had greater areal coverage of shrublands and less of woodlands. The altered vegetation structure along dewatered rivers may lower wildlife habitat quality. This study provides river managers with quantitative hydrologic guidelines for conserving tall dense P. fremontii-S. gooddingii stands and emphasizes the importance of maintaining long-term hydrologic conditions that are favorable to these species. The study also has implications for riparian restoration and invasive species management by suggesting that desired outcomes may be achieved through restoration of physical processes.     

Competition between invasive earthworms (Amynthas corticis, Megascolecidae) and native North American millipedes (Pseudopolydesmus erasus, Polydesmidae): Effects on carbon cycling and soil structure

Invasive earthworms can have significant impacts on C dynamics through their feeding, burrowing, and casting activities, including the protection of C in microaggregates and alteration of soil respiration. European earthworm invasion is known to affect soil micro- and mesofauna, but little is known about impacts of invasive earthworms on other soil macrofauna. Asian earthworms (Amynthas spp.) are increasingly being reported in the southern Appalachian Mountains in southeastern North America. This region is home to a diverse assemblage of native millipedes, many of which share niches with earthworm species. This situation indicates potential for earthworm-millipede competition in areas subject to Amynthas invasion.In a laboratory microcosm experiment, we used two ¹³C enriched food sources (red oak, Quercus rubra, and eastern hemlock, Tsuga canadensis) to assess food preferences of millipedes (Pseudopolydesmus erasus), to determine the effects of millipedes and earthworms (Amynthas corticis) on soil structure, and to ascertain the nature and extent of the interactions between earthworms and millipedes. Millipedes consumed both litter species and preferred red oak litter over eastern hemlock litter. Mortality and growth of millipedes were not affected by earthworm presence during the course of the experiment, but millipedes assimilated much less litter-derived C when earthworms were present.Fauna and litter treatments had significant effects on soil respiration. Millipedes alone reduced CO₂ efflux from microcosms relative to no fauna controls, whereas earthworms alone and together with millipedes increased respiration, relative to the no fauna treatment. CO₂ derived from fresh litter was repressed by the presence of macrofauna. The presence of red oak litter increased CO₂ efflux considerably, compared to hemlock litter treatments.Millipedes, earthworms, and both together reduced particulate organic matter. Additionally, earthworms created significant shifts in soil aggregates from the 2000-250 and 250-53 μm fractions to the >2000 μm size class. Earthworm-induced soil aggregation was lessened in the 0-2 cm layer in the presence of millipedes. Earthworms translocated litter-derived C to soil throughout the microcosm.Our results suggest that invasion of ecosystems by A. corticis in the southern Appalachian Mountains is unlikely to be limited by litter species and these earthworms are likely to compete directly for food resources with native millipedes. Widespread invasion could cause a net loss of C due to increased respiration rates, but this may be offset by C protected in water-stable soil aggregates.     

The impacts of Phalaris arundinacea (reed canarygrass) invasion on wetland plant richness in the Oregon Coast Range, USA depend on beavers

Invasive plants can threaten diversity and ecosystem function. We examined the relationship between the invasive Phalaris arundinacea (reed canarygrass) and species richness in beaver wetlands in Oregon, USA. Four basins (drainages) were chosen and three sites each of beaver impoundments, unimpounded areas and areas upstream of debris jams were randomly chosen in each basin for further study (n = 36). Analysis of covariance (ANCOVA) showed that the relationship between Phalaris and species richness differed significantly (p = 0.01) by site type. Dam sites (beaver impoundments) exhibited a strong inverse relationship between Phalaris and species richness (b_D = −0.15), with one species lost for each 7% increase in Phalaris cover. In contrast, there was essentially no relationship between Phalaris cover and species richness in jam sites (debris jam impoundments formed by flooding; b_J = +0.01) and unimpounded sites (b_U = −0.03). The cycle of beaver impoundment and abandonment both disrupts the native community and provides an ideal environment for Phalaris, which once established tends to exclude development of herbaceous communities and limits species richness. Because beaver wetlands are a dominant wetland type in the Coast Range, Phalaris invasion presents a real threat to landscape heterogeneity and ecosystem function in the region.     

Habitat selection by the pale-headed brush-finch (Atlapetes pallidiceps) in southern Ecuador: implications for conservation

The pale-headed brush-finch (Atlapetes pallidiceps) is threatened with extinction due to habitat loss, but very little is known about its ecological requirements. We used multiple logistic regression to study habitat selection of this species at landscape, territory, and nest site scales in order to make recommendations about effective management. Habitat selection by the sympatric stripe-headed brush-finch (Buarremon torquatus) was examined with the same methods in order to analyse interspecific resource partitioning and potential competition. The pale-headed brush-finch selected semi-open habitat types with intermediate scrub heights, and avoided forests. Nest sites depended on the presence of vines or bamboo. By contrast, the stripe-headed brush-finch chose dense habitat with low ground cover under tall vegetation and avoided semi-open habitat. The two species had overlapping territories but differed significantly in microhabitat use and the use of vegetation strata. We found no convincing evidence that the stripe-headed brush-finch displaces the pale-headed brush-finch from optimal habitat. The preservation of semi-open scrubland maintained by low-intensity grazing is suggested for future conservation of the pale-headed brush-finch.     

Habitat selection of endangered and endemic large flying-foxes in Subic Bay, Philippines

Large flying-foxes in insular Southeast Asia are the most threatened of the Old World fruit bats due to high levels of deforestation and hunting and effectively little local conservation commitment. The forest at Subic Bay, Philippines, supports a rare, large colony of vulnerable Philippine giant fruit bats (Pteropus vampyrus lanensis) and endangered and endemic golden-crowned flying-foxes (Acerodon jubatus). These large flying-foxes are optimal for conservation focus, because in addition to being keystone, flagship, and umbrella species, the bats are important to Subic Bay’s economy and its indigenous cultures. Habitat selection information streamlines management’s efforts to protect and conserve these popular but threatened animals. We used radio telemetry to describe the bats’ nighttime use of habitat on two ecological scales: vegetation and microhabitat. The fruit bats used the entire 14,000 ha study area, including all of Subic Bay Watershed Reserve, as well as neighboring forests just outside the protected area boundaries. Their recorded foraging locations ranged between 0.4 and 12 km from the roost. We compared the bats’ use to the availability of vegetative habitat types, riparian areas, and bat trees. The fruit bats’ locations showed a preference for undisturbed forest types and selection against disturbed and agricultural areas. Bat locations also showed selection for particular fruiting/flowering bat trees. The bats showed strong preference for riparian areas; locations were in riparian areas over four times more than expected. From these results we recommend that management focus flying-fox conservation efforts on undisturbed forest and riparian areas.     

Habitat of endangered white abalone, Haliotis sorenseni

Surveys with a submersible at offshore islands and banks in southern California found that white abalone were most abundant at depths between 43 and 60 m. This is deeper than estimates taken when white abalone were more abundant. Densities were highest at sites far from fishing ports. Controlling for depth and site found that white abalone were significantly more abundant in areas with Laminaria farlowii (an alga) but abalone were not associated with areas high in the cover of other algae (Pelagophycus porra or Eisenia arborea) or the amount of sand in the habitat (except that abalone always occurred on rock). Within an area with abalone, the particular rock they occurred on was significantly larger than unoccupied neighboring rocks. Occupied rocks were not significantly different in algal cover or in sea urchin density than unoccupied neighboring rocks. The position of abalone on a rock was nearer to the rock-sand interface than would be expected based on a random distribution. More white abalone were feeding when in association with red urchins, perhaps because both grazers capture drift algae to eat. These data may aid future efforts to locate white abalone brood stock and identify locations for outplanting.     

Polyphasic characteristics of bradyrhizobia isolated from nodules of peanut (Arachis hypogaea) in China

Peanuts (Arachis hypogaea L.) were introduced to China about 500 years ago. However, the diversity of Rhizobial strains in China that can nodulate peanut was poorly understand. Diversity and phylogeny of 50 slow-growing strains, isolated from root nodules of peanut in different geographical regions of China, were studied using polyphasic techniques. All stains were clustered by phenotypic tests into two distinct groups: Group I: 16S rRNA RFLP genotype 3, and Group II, which divided into 16S rRNA RFLP genotypes 1 and 2. Genotype 1 shares the same genotype with USDA110, USDA122 and USDA127 of Bradyrhizobium japonicum, and genotype 2 solely consisted of extra-slow growing bradyrhizobia isolated from Hongan, China. Results of 16S rRNA sequencing revealed that peanut bradyrhizobia were phylogenetically related to B. japonicum and their sequence divergence was less than 1.1%. Based upon the size of the internally transcribed spacer (ITS) between the16S and 23S RNA genes, strains were classified into ITS-I, ITS-II and ITS-III genotypes. Strains could be further divided into sub-clusters IA, IB, IIa, IIb and IIc five sub-clusters through ITS PCR-RFLP and repetitive extragenic palindromic PCR (REP-PCR) analysis. Host specificity test revealed that all peanut bradyrhizobia tested nodulated Phaseolus vulgaris and strains of clusters IIb and IIc nodulated Glycine soja efficiently. Bradyrhizobia isolated from peanut were related, but still exhibited phylogenetical divergence with B. japonicum.     

Genetic and demographic responses of fragmented Acacia dealbata (Mimosaceae) populations in southeastern Australia

Genetic and demographic studies of fragmented populations of common plant species often reveal negative impacts that are likely to constrain persistence. Examining species that are broadly representative of functional groups within fragmented landscapes is one approach to providing a better understanding of how these processes will influence vegetation persistence. Acacias are a significant component of the Australian flora, with Acacia dealbata being a common and representative species of fragmented landscapes across New South Wales. Previous reproductive assessments of fragmented A. dealbata populations indicated significant constraints for small populations through low reproductive output mediated by fertilisation success. This study examined genetic diversity, mating system, and progeny growth parameters of the seed crops produced by these populations to assess whether further constraints to persistence could be detected. Spatially explicit simulation studies were also conducted to assess the persistence likelihood of fragmented populations. Landscape parameters such as population size and plant density were useful predictors for some of the genetic and demographic responses, but a poor response signal was generally observed. Strong evidence for a self-incompatibility mechanism was observed in A. dealbata and is likely to be the major driver of population persistence. Self-incompatibility in small populations limits mate availability and eliminates inbred progeny early in the reproductive cycle leading to poor reproductive output. The simulation data provides further evidence that mate limitation in smaller populations (<200 plants and 40 S alleles) constrains reproductive output and persistence. These data indicate that introducing new germplasm to smaller populations can dramatically improve their persistence likelihood.     

Distribution, status, and conservation needs of the golden-crowned sifaka (Propithecus tattersalli)

The golden-crowned sifaka is considered one of the world's most endangered primates. To evaluate the species' current conservation status we established its actual distribution and abundance, and assessed current threats that affect its survival. Study methods involved direct sifaka observations and interviews to local villagers. Propithecus tattersalli's distribution is restricted to the region comprised between the Loky and Manambato rivers. Throughout its range, the species is abundant and it can even be found in small forest fragments, although it was never observed at elevations above 700 m.a.s.l. Major threats to the species include habitat destruction through slash-and-burn agriculture, grass fires, wood and gold extraction, and poaching. Total population estimates range from 6100 to 10,000 individuals, with an effective population size of approximately 2500-4000 sifakas. Though sensitive to forest destruction, the species seems to be resilient to current levels of landscape fragmentation. We recommend the establishment of a system of protected areas throughout the Loky-Manambato region and the implementation of a “Flagship Species Program” utilizing the golden-crowned sifaka as a catalyst for a regional Conservation Management Plan.     

Herbicides, weeds and endangered species: management of bitou bush (Chrysanthemoides monilifera ssp. rotundata) with glyphosate and impacts on the endangered shrub, Pimelea spicata

Environmental weed invasion threatens the biodiversity of native species. Unfortunately, managing these weeds may also affect biodiversity adversely. A recent example occurred when glyphosate, a herbicide used to control the highly invasive weed, bitou bush (Chrysanthemoides monilifera ssp. rotundata), accidentally drifted over a small population of an endangered shrub, Pimelea spicata. Following concerns that the affected population would not recover and, thereby, cause the local extinction of P. spicata, we conducted a series of glasshouse and field experiments to explore the impacts of glyphosate on this endangered species. Seedlings and young plants of P. spicata, in which the tap root was undeveloped, were killed by a single application of glyphosate. Older plants with a well developed tap root also died back initially, but about 50% of individuals re-sprouted. This re-growth was associated with a significant decrease in tap root diameter, implying that further disturbance, including repeated treatment with glyphosate, would kill plants by impairing their potential for recovery. Unlike some sclerophyllous native shrubs, the tolerance of P. spicata to glyphosate was limited, even when its growth was slowed artificially by limiting water availability. Winter applications of glyphosate to manage infestations of bitou bush will impact adversely on populations of P. spicata and may also affect the other rare and endangered species whose survival is threatened by this species, even though some natives are unaffected by the herbicide. Protecting native biodiversity from bitou bush will involve sustainable weed management that minimises impacts on non-target native species.     

Red alder (Alnus rubra) alters community-level soil microbial function in conifer forests of the Pacific Northwest, USA

Nitrogen-fixing tree species have been shown to improve site fertility and increase N transformation rates, but the influence of N-fixing plants on the soil microbial community as a whole is largely unknown. We used patterns of individual carbon-source utilization and enzyme activities to assess the relative effects of N-fixing red alder on the soil microbial community in three adjacent stands (pure conifer, mixed alder-conifer, and pure alder) of a highly productive coastal Oregon forest where the density of red alder has been experimentally manipulated for over 65 years. Two major patterns were revealed: (1) bacterial and fungal carbon-source utilization patterns in soil from pure conifer stands were significantly different from both pure alder soils and mixed conifer-alder soils, while there was no difference in substrate utilization patterns between soils from the mixed alder-conifer and pure alder stands; and (2) the activities of nine extracellular enzymes involved in ligno-cellulose degradation and the mineralization of organic nitrogen, phosphate, and sulfate compounds were all significantly greater in pure alder soils compared to either pure conifer or mixed conifer-alder soils. Our results show that, in addition to an overall increase in soil fertility, microbial biomass, and microbial activity, the presence of N-fixing red alder significantly alters the physiological profile of the microbial community-even in an ecosystem already of high N status.     

Genetic variation in captive population of chinese alligator, Alligator sinensis, revealed by random amplified polymorphic DNA (RAPD)

Chinese alligator (Alligator sinensis) is an endemic species in China. The likely extinction of it in the wild has been recognised. To prevent this species becoming extinct, the Anhui Research Centre of Chinese Alligator Reproduction (ARCCAR) was established in Xuanzhou, Anhui Province in 1979, where has been established the largest captive population of Chinese alligator (XZSP) in the world. Another farm (CXSP) was established by villagers in Changxin, Zhejiang Province. The results of an investigation of the two captive subpopulation structures by genetic analysis are presented in this paper. We examined the genetic variation in the two captive subpopulations using RAPDs. Thirty-one random primers were selected among 199 random primers screened. A total of 193 reproducible RAPD fragments were scored among 43 individuals, of which 21 (10.88%) were polymorphic. The genetic distances between 43 individuals ranged from 0 to 0.0376 with average of 0.0104±0.0055 S.E. The genetic similarity in CXSP (0.9948±0.0029 S.E.) was higher than that in XZSP (0.9894±0.0055 S.E.). The founder effect is a possible explanation for very low genetic variation in CXSP. Analysis of the RAPD data showed that the mean phenotypic band frequencies of each polymorphic loci was 0.6656±0.3730 S.E. The lowest phenotypic band frequency (0.0233) was found in four of those polymorphic loci. There was no genetic difference between the two subpopulations (D_ij=0.0009). According to the dendrogram and the distribution of polymorphic fragments in two subpopulations, CXSP originated genetically from XZSP. This paper summarises a preliminary research on genetic structure in populations of Chinese alligator. Although there is higher genetic similary (0.9896±0.0055 S.E.) in captive population of A. sinensis, we did not determine whether or not loss of genetic variation had occurred in relation to a wild control population. The data of malformed offspring will be collected carefully, and wild samples be added to set up a control population in future study.     

Habitat suitability, threats and conservation of isolated populations of the smooth snake (Coronella austriaca) in the southern Iberian Peninsula

During the Pleistocene, climatic fluctuations due to glacial and interglacial periods greatly modified the distribution of boreal organisms. One direct effect of these distribution shifts is that, along the southern edge of the range of some boreal species, populations persist only in isolated patches of suitable habitats, surrounded by less suitable areas. Isolated populations in marginal habitat are vulnerable to several threats, including climate change, anthropogenic threats, and stochastic events. We developed habitat-suitability models using Ecological Niche Factor Analysis for populations of the smooth snake, Coronella austriaca, at the southernmost limit of the species range. These models were based on historical and current records of occurrence, coupled with remote sensing data including elevation, slope, and climatic variables. Our results indicated that C. austriaca in the Iberian Peninsula occurred in areas associated with high slope and precipitation, low temperatures, and low variation in seasonal temperature and precipitation compared to areas of non-occurrence. At a broad scale, the areas classified as highly suitable for the species in the southern Iberian Peninsula were small and fragmented. At a local scale, extensive field work demonstrated that C. austriaca occurs in low densities in these areas. In addition, we detected several human-induced threats like habitat loss, favoured by temperature increase and rainfall reduction. Several life-history traits, such as dietary specialization and low frequency reproduction, also may contribute to the vulnerability of these populations to local extinctions. Although the most suitable southernmost areas are included in protected reserves, specific guidelines for management are needed to assess conservation needs.     

Ex situ genetic conservation of endangered Vatica guangxiensis (Dipterocarpaceae) in China

RAPD polymorphisms were applied to check the efficiency of ex situ genetic conservation of endangered Vatica guangxiensis X. L. Mo. endemic to southwestern China. Low level of genetic variation was revealed in three remaining natural populations. Twenty random primers, each with 10 base pairs, generated 231 bands with 53.68% being polymorphic, and with an average of 32.46% being polymorphic in each natural population. Strong population differentiation was revealed by AMOVA (analysis of molecular variance) and Gst value was 0.3764. The population ML ex situ conserved in the Xishuangbanna Tropical Botanical Garden contained an intermediate genetic variation compared with natural populations, with 30.74% bands being polymorphic. Of the total 231 bands generated in V. guangxiensis, 204 bands were also detected in population ML, indicating that 88.31% of the total genetic variations of this species were conserved in ex situ population. If only the alleles with moderate to high frequency (P>0.05) were considered, 204 out of 209 bands (97.61%) occurred in ex situ population ML. RAPD analysis also detected one exclusive band in natural population NS, and five in natural population NP, three of these exclusive bands were generated in every samples of natural population (NP), and other three had moderate to high frequencies. While none of these exclusive bands were detected in ex situ conserved population ML. Our conclusions are that the ex situ conserved population ML contains representative genetic variation to maintain long-term survival and evolutionary process of V. guangxiensis, and that more extensive ex situ sampling in natural population NS and NP is needed to conserve more exclusive alleles in ex situ population. The tropical area in the Botanical Garden would play a more important role in the ex situ conservation of rare and endangered plants.     

Rapid eradication of feral pigs (Sus scrofa) from Santa Cruz Island, California

Eradication of invasive alien species from islands is often necessary to protect native biota. The rapidity in which eradication projects are implemented can help reduce risk they will fail. We describe the eradication of feral pigs (Sus scrofa) from Santa Cruz Island, California, highlighting those control techniques that removed the most pigs and those that removed the last pigs. In 411 days, a total of 5036 pigs were removed from the 25,000-ha island. Before the eradication began, the island was fenced into five zones. Within each zone, the same general sequence of control methods was used: trapping (16% of dispatches in 1660 trap-nights); aerial shooting from a helicopter (77% of dispatches in 13,822 km of flight path); and then ground-based hunting with trained dogs (5% of dispatches in 1111 hunter-days). Sterilized adult pigs fitted with radio collars were subsequently used to aid in the location of surviving wild pigs and to monitor the success of the project. Female telemetered pigs were more effective than males at locating remaining wild pigs. Only 10% of the last 102 pigs (the last 20 or so present in each fenced zone) were dispatched as a result of being found with a telemetered pig, but telemetered animals were responsible for finding 43% of the very last pigs once normal hunting had ceased. The time taken to eradicate pigs on Santa Cruz Island was about half that taken on a neighbouring island of similar size (Santa Rosa Island) and 12 times as fast as that on Santiago Island (58,465 ha), Galapagos Islands. The deliberate sequencing of control methods, using first those that taught surviving pigs the least, and the intensive implementation of those methods, represent important advances in the practice of eradication and so biodiversity conservation.     

Hydrolytic enzyme activities in maize (Zea mays) and sorghum (Sorghum bicolor) roots inoculated with Gluconacetobacter diazotrophicus and Glomus intraradices

Two strains of Gluconacetobacter diazotrophicus (Pal 5, UAP5541) and the arbuscular mycorrhizal fungus Glomus intraradices increased both the shoot and root dry weight of sorghum 45 days after inoculation, whereas they had no effect on the shoot and root dry weight of maize. Co-inoculation (Gluconacetobacter diazotrophicus plus Glomus mosseae) did not increase the shoot and root dry weight of either plant. There was a synergistic effect of Gluconacetobacter diazotrophicus on root colonization of maize by Glomus intraradices, whereas an antagonistic interaction was observed in the sorghum root where the number of Gluconacetobacter diazotrophicus and the colonization by Glomus intraradices were reduced. Plant roots inoculated with Gluconacetobacter diazotrophicus and Glomus intraradices, either separately or together, significantly increased root endoglucanase, endopolymethylgalacturonase and endoxyloglucanase activities. The increase varied according to the plant. For example, in comparison with non-inoculated plants, there were higher endoglucanase (+328%), endopolymethylgalacturonase (+180%) and endoxyloglucanase (+125%) activities in 45-day old co-inoculated maize, but not in 45-day old sorghum. The possibility is discussed that hydrolytic enzyme activities were increased as a result of inoculation with Gluconacetobacter diazotrophicus, considering this to be one of the mechanisms by which these bacteria may increase root colonization by AM fungi.     

Survival of the western pond turtle (Emys marmorata) in an urban California environment

The western pond turtle Emys (formerly Clemmys) marmorata is declining throughout its range, primarily due to loss of habitat via urbanization and conversion to agriculture. Urban waterways present several important challenges to freshwater turtle populations, but they also present an opportunity to maintain declining species in a ubiquitous habitat that has high public visibility. The arboretum waterway on the University of California, Davis campus is an example of an extensively altered urban habitat that supports a relatively large E. marmorata population. Over the last 6 years, we monitored the turtle population inhabiting the arboretum waterway to determine the demographic health of the population, and the challenges and opportunities that urban environments pose for pond turtles. Since 1993, the naturally existing arboretum pond turtle population has declined by approximately 40% and has shown little natural recruitment. During this time, we also introduced 31 headstarted turtles into the arboretum. Headstarting is the process of raising juveniles in captivity until they have outgrown their period of greatest vulnerability to predators, and then releasing them into the wild. Our headstarting results demonstrate that this contentious strategy is a viable option for adding young turtles to the population, although it does not address the causes of decline. Over the course of our study, we encountered nine species of non-native turtles in the waterway, and these appear to be a serious threat to the native species. As more habitat becomes urbanized, it is increasingly important to understand how freshwater turtles, such as E. marmorata, adapt to urban waterways and the impact of non-native turtles on native turtle species. Our strong feeling is that urban waterways can provide habitat for viable populations of freshwater turtles and showcase them to the public, but both the aquatic and terrestrial habitat must be managed according to the biological requirements of individual species.     

Agricultural insect pest compromises survival of two endemic Braya (Brassicaceae)

Agro-ecosystems support a vast array of non-native insects, but the potential of these insects to invade and degrade natural ecosystems is largely unknown. Plutella xylostella L. (diamondback moth) is a global agricultural pest that is not native to North America. It feeds on members of the Brassicaceae family, including the endangered Braya longii (Fernald) (Long’s braya) and threatened B. fernaldii (Abbe) (Fernald’s braya) which are endemic to the limestone barrens of Newfoundland, Canada. The immigration of P. xylostella from overwintering sites in the United States to this rare natural ecosystem was monitored with pheromone traps between 2003 and 2005. After their mass immigration in early summer, females lay eggs on an average of 30% of the B. longii and 16% of the B. fernaldii population. Larval feeding reduces the mean seed output of infested plants by 60%, from 10.8 to 4.3 seeds/fruit, and damages 26% of their leaves. There are residual and long-term effects of this herbivory, as many dead braya had higher numbers of eggs, and subsequent leaf and fruit damage one to three years before they died. High summer air temperatures and low precipitation allowed this pest to become multivoltine, resulting in additive damage to braya individuals. Presently, insufficient attention is directed to the impacts of agricultural pests on native ecosystems and rare host plants; hence, there is a need for both the conservation and agricultural communities to cooperate in mitigating the impacts of these pests on native biodiversity.     

Reproductive biology and conservation implications of three endangered snapdragon species (Antirrhinum, Plantaginaceae)

About 32% of Antirrhinum species are considered to be endangered; however, no field studies have focused on their reproductive biology. In this work, several aspects of the reproductive biology (flowering phenology, floral biology, breeding system) and potential limits on seed quantity and quality (pollen limitation, inbreeding depression) were studied in natural populations of three endangered species of the genus (Antirrhinum charidemi, Antirrhinum subbaeticum, Antirrhinum valentinum). Results disclose that all three species need insect visitors for seed production since fruit set after autonomous self-pollination was lower than under hand cross-pollination. A. charidemi and A. valentinum were mainly self-incompatible, whereas A. subbaeticum was self-compatible but herkogamous. Supplementary pollination in open-pollinated flowers only increased fruit set and seed set relative to controls in a given population of A. valentinum. Preliminary data on inbreeding depression at early life-cycle stages of the self-compatible A. subbaeticum revealed that the cumulative level was low. Despite the three species being closely related and sharing many ecological characteristics, they show different mating systems, and different factors limit seed quantity and quality. Thus, caution should be taken when making a common conservation plan for a group of closely related taxa.