Ecology Of Individual Species Research Articles

Complex Trophic Interactions in an Acidophilic Microbial Community.

Extreme habitats often harbor specific communities that differ substantially from non-extreme habitats. In many cases, these communities are characterized by archaea, bacteria and protists, whereas the number of species of metazoa and higher plants is relatively low. In extremely acidic habitats, mostly prokaryotes and protists thrive, and only very few metazoa thrive, for example, rotifers. Since many studies have investigated the physiology and ecology of individual species, there is still a gap in research on direct, trophic interactions among extremophiles. To fill this gap, we experimentally studied the trophic interactions between a predatory protist (Actinophrys sol, Heliozoa) and its prey, the rotifers Elosa woralli and Cephalodella sp., the ciliate Urosomoida sp. and the mixotrophic protist Chlamydomonas acidophila (a green phytoflagellate, Chlorophyta). We found substantial predation pressure on all animal prey. High densities of Chlamydomonas acidophila reduced the predation impact on the rotifers by interfering with the feeding behaviour of A. sol. These trophic relations represent a natural case of intraguild predation, with Chlamydomonas acidophila being the common prey and the rotifers/ciliate and A. sol being the intraguild prey and predator, respectively. We further studied this intraguild predation along a resource gradient using Cephalodella sp. as the intraguild prey. The interactions among the three species led to an increase in relative rotifer abundance with increasing resource (Chlamydomonas) densities. By applying a series of laboratory experiments, we revealed the complexity of trophic interactions within a natural extremophilic community.

The communities of terrestrial macrofungi in different forest types in vicinities of Khanty-Mansiysk (middle taiga zone of West Siberia).

BackgroundThe diversity of macrofungi in the vicinities of Khanty-Mansiysk (Yugra, Russia) was surveyed using a method of permanent sampling plots. Ten plots, each consisting of a number of micro-plots, were established in several different communities ranging from old-growth mixed taiga forest to its derivatives in cutting succession and bogged areas. For more complete registration of the mycota, plots were supplemented with random walking routes directly nearby. Survey results were subjected to various quantitative analyses which allowed not only to evaluate the diversity of fungi but also to obtain valuable information on occurrence, abundance and ecology of individual species as well as community structure and its dynamics in the course of ecological succession. The paper reports the results of the first year of observations.New information460 species of terrestrial macrofungi revealed in a poorly explored area in middle taiga of West Siberia. The plot-based study revealed differences between communities of terrestrial macrofungi of old coniferous forests, their after-cutting secondary formations and bogged stages. The survey allowed to reveal records of 3 species listed in the Red Data Book of Russia and 9 species listed in the Red Data Book of Yugra.

Two newly recognized species of Hemidactylus (Squamata, Gekkonidae) from the Arabian Peninsula and Sinai, Egypt

A recent molecular phylogeny of the Arid clade of the genus Hemidactylus revealed that the recently described H. saba and two unnamed Hemidactylus species from Sinai, Saudi Arabia and Yemen form a well-supported monophyletic group within the Arabian radiation of the genus. The name ‘Hemidactylus saba species group’ is suggested for this clade. According to the results of morphological comparisons and the molecular analyses using two mitochondrial (12S and cytb) and four nuclear (cmos, mc1r, rag1, rag2) genes, the name Hemidactylus granosus Heyden, 1827 is resurrected from the synonymy of H. turcicus for the Sinai and Saudi Arabian species. The third species of this group from Yemen is described formally as a new species H. ulii sp. n. The phylogenetic relationships of the members of ‘Hemidactylus saba species group’ are evaluated and the distribution and ecology of individual species are discussed.

Shellfish, Seasonality, and Stable Isotope Sampling: δ18O Analysis of Mussel Shells From an 8,800-Year-Old Shell Midden on California's Channel Islands

ABSTRACT Analyzing stable isotopes in mollusk shells allows archaeologists to address issues ranging from seasonality of harvest, to settlement and subsistence strategies, sea surface temperatures, and nearshore paleoecology. Studying California mussel shells from an ∼8,800-year-old shell midden on San Miguel Island, we investigate how mollusk growth rates influence sampling strategies for determining seasonality. Using a fully profiled shell as a standard to interpret more limited measurements (terminal growth band plus one) on 39 additional shells, we identified what appeared to be a multi-seasonal occupation. Sampling 20 of the 39 shells more intensively, however, changed our conclusions about season of harvest for 35 percent of the analyzed shells, producing data more consistent with other evidence for a short-term occupation of CA-SMI-693. Sampling strategies for determining seasonality from marine mollusks should carefully consider the ecology of individual species, particularly for fast-growing shellfish such as California mussels. [Supplementary material is available for this article. Go to the publisher's online edition of Journal of Island & Coastal Archaeology for the following free supplemental resource(s): Appendix 1. Reported δ13C and δ18O and inferred temperature values for all isotopic determinations from forty analyzed California mussel shells from CA-SMI-693.]

Relationships of exotic plant communities with native vegetation, environmental factors, disturbance, and landscape ecosystems of Pinus ponderosa forests, USA

Invasions by exotic plant species can threaten forest ecosystems in numerous ways. Theories on relationships of exotic species invasions with native vegetation, resource availability, and disturbance could assist in managing exotic plants by identifying parts of the landscape and ecological conditions most susceptible to invasion. However, generality of these theories is complicated by considerable variation among landscapes and ecology of individual species. We assessed hypotheses on relationships of exotic plant communities with native vegetation, environmental (soil, topographic, and climate), and disturbance (roads and grazing) variables using data from 66 plots within a 110,000-ha Pinus ponderosa forest landscape in northern Arizona, USA. We further assessed exotic plant relationships with ecosystem classification, which has a long history of use in forest ecology and management but has been underutilized for understanding exotic species distributions. Plots contained a total of 251 native and 20 exotic plant species. As hypothesized for distributional studies, native and exotic species were positively correlated, but the correlation varied with scale for species richness (m2, r=0.65; 500m2, r=0.41) and was weaker for cover (r=0.32). Multiple regression, including native vegetation and environmental variables, accounted for similar amounts of variation in exotic species richness (50% of variation) and cover (51%). Disturbance variables only entered regression models when native vegetation was excluded from models. Exotic species richness m−2, cover, and community composition were strongly related to the ecosystem classification. For example, mean exotic cover ranged from <0.1% in ecosystems with volcanic cinder soils to 7% in ecosystems containing Populus tremuloides. As hypothesized, moist ecosystems were generally most invaded. However, also considering factors such as past management of the ecosystems and literature on the introduction histories (e.g., intentional seeding for range improvement) of the species, we hypothesize that the ecosystem classification integrated co-varying environmental, disturbance, and management variables related to exotic plant communities. Ecosystem classification was a useful framework for understanding distributions of exotic plant communities across the landscape.

A comparison of tree seedling growth in artificial gaps of different sizes in two contrasting forest types.

One of the major concerns in forestry in the tropics is the lack of information on the impact of canopy disturbance through logging. The degree of canopy opening that should be allowed during logging to enhance natural regeneration of timber tree species is not known. Information on the seedling ecology of individual species and ecological species groups on which to base management decisions are also lacking. Experiments to determine the ecophysiological responses of seedlings of timber tree species to different irradiances in two forest sites were carried out. The two forest reserves are Nkrabia and Tinte Bepo in the Moist Evergreen and Moist Semi-Deciduous Forest Types, respectively. Eight species, representing three Shade Bearers, four Non-Pioneer Light Demanders and one Pioneer species, were grown in a series of artificially-created gaps in two forest sites differing in annual rainfall. The forest shade received 1-2% irradiance, while the artificial gaps received 5, 10, 15, 30 and 65% irradiance. Seedling growth was greater at Nkrabia Forest Reserve (Moist Evergreen Forest Type) than at Tinte Bepo Forest Reserve (Moist Semi-Deciduous Forest Type). This is probably due to the lower soil moisture stress at Nkrabia as a result of more rainfall. Lower moisture stress at Nkrabia may also explain the greater leaf area and specific leaf area ratios, lower leaf turnover and lower number of small leaves on plants than those at Tinte Bepo. Response of height growth to irradiance of Shade Bearers and Non-Pioneer Light Demanders was similar but different from that of Pioneer species.

Modelling plant species richness using functional groups

Conservation biologists increasingly rely on spatial predictive models of biodiversity to support decision-making. Therefore, highly accurate and ecologically meaningful models are required at relatively broad spatial scales. While statistical techniques have been optimized to improve model accuracy, less focus has been given to the question: How does the autecology of a single species affect model quality? We compare a direct modelling approach versus a cumulative modelling approach for predicting plant species richness, where the latter gives more weight to the ecology of functional species groups. In the direct modelling approach, species richness is predicted by a single model calibrated for all species. In the cumulative modelling approach, the species were partitioned into functional groups, with each group calibrated separately and species richness of each group was cumulated to predict total species richness. We hypothesized that model accuracy depends on the ecology of individual species and that the cumulative modelling approach would predict species richness more accurately. The predictors explained plant species richness by ca. 25%. However, depending on the functional group the deviance explained varied from 3 to 67%. While both modelling approaches performed equally well, the models of the different functional groups highly varied in their quality and their spatial richness pattern. This variability helps to improve our understanding on how plant functional groups respond to ecological gradients.

MATCHING MORPHOLOGY AND DIET IN THE DISC-WINGED BAT THYROPTERA TRICOLOR (CHIROPTERA)

The dietary niche and morphological adaptations of a species should be highly correlated. However, conflicting selective pressures may make predictions about diet difficult without additional knowledge of a species' life history. We tested the reliability of predicting a bat's diet from its wing morphology using data for Spix's diskwinged bat (Thyroptera tricolor). The species had been predicted to fall within either the aerial hawking or gleaning foraging group. We compared the results of a theoretical (canonical discriminant function analysis of morphology) and an applied (analysis of droppings) method of diet determination. Our results place T. tricolor in the gleaning functional group with a 77% probability according to morphology. Correspondingly, a large proportion of the diverse diet consisted of nonflying prey, such as spiders, insect larvae, and other silent prey, which should be difficult to detect using echolocation. Although some flying prey were taken, it is clear that T. tricolor regularly gleans prey from surfaces, indicating that for this species, morphology is a useful indicator of diet. However, the breadth of the diet; the high proportion of jumping spiders, leafhoppers, and insect larvae; and the extremely small size of prey were unique features of the diet that could not be predicted from morphology alone. Thus, although comparative statistical methods and the analysis of wing morphology may be helpful to predict the general ecological niche, only detailed investigation of the life history may yield the detail needed for understanding the link between morphology and ecology of individual species.

Facilitation and interference among three predators affect their consumption of a stream‐dwelling mayfly

Summary1. We experimentally tested if a multiplicative risk model accurately predicted the consumption of a common mayfly at risk of predation from three predator species in New Zealand streams. Deviations between model predictions and experimental observations were interpreted as indicators of ecologically important interactions between predators.2. The predators included a drift‐feeding fish [brown trout (T), Salmo trutta], a benthivorous fish [galaxiid (G), koaro, Galaxias brevipennis] and a benthic predatory stonefly (S; Stenoperla sp.) with Deleatidium sp. mayflies as prey. Eight treatments with all predator species combinations and a predator‐free control were used. Experiments were performed in aquaria with cobbles as predator refuges for mayflies and we measured the proportion of prey consumed after 6 h for both day and night trials.3. Trout consumed a higher proportion of prey than other predators. For the two predator treatments we found less than expected prey consumption in the galaxiid + trout treatment (G + T) for both day and night trials, whereas a higher than expected proportion of prey was consumed during night time in the stonefly + trout (S + T) treatment.4. The results indicate interference (G + T) and facilitation (S + T) between predators depending on predator identity and time of day. Thus, to make accurate predictions of interspecific interactions, it is necessary to consider the ecology of individual species and how differences influence the direction and magnitude of interactions.

Fish assemblage structure and relations with environmental conditions in a Rocky Mountain watershed

Fish and habitat were sampled from 110 reaches in the Salt River basin (Idaho and Wyoming) during 1996 and 1997 to assess patterns in fish assemblage structure across a Rocky Mountain watershed. We identified four distinct fish assemblages using cluster analysis: (1) allopatric cutthroat trout (Oncorhynchus clarki (Richardson, 1836)); (2) cutthroat trout – brook trout (Salvelinus fontinalis (Mitchell, 1814)) – Paiute sculpin (Cottus beldingi Eigenmann and Eigenmann, 1891); (3) cutthroat trout – brown trout (Salmo trutta L., 1758) – mottled sculpin (Cottus bairdi Girard, 1850); and (4) Cyprinidae–Catostomidae. The distribution of fish assemblages was explained by thermal characteristics, stream geomorphology, and local habitat features. Reaches with allopatric cutthroat trout and the cutthroat trout – brook trout – Paiute sculpin assemblage were located in high-elevation, high-gradient streams. The other two fish assemblages were generally located in low-elevation streams. Associations between habitat gradients, locations of reaches in the watershed, and occurrence of species were further examined using canonical correspondence analysis. The results suggest that stream geomorphology, thermal conditions, and local habitat characteristics influence fish assemblage structure across a Rocky Mountain watershed, and they provide information on the ecology of individual species that can guide conservation activities.

Cymatium corrugatum (Lamarck 1816) gastropoda, prosobranchia. A new species for the Adriatic

Very valuable papers concerning malacology of the Adriatic Sea deal, for the most part, with the systematics, whereas there is a substantial number of papers with very scarce information on the ecology of individual species. Since I intended to provide some more comprehensive data on individual species, rather complex bionomic and biocoenological research was undertaken aiming to study the taxonomy and the ecology of the Prosobranchiata group. Present research covered different biotopes of the northern, middle and southern Adriatic, both in the shallow coastal and deeper open littoral, and hard and mobile bottoms. Material was collected in two ways: 1) Scuba diving or direct collection and observations; and 2) an indirect method of collection of samples by Petersen grab, dredge and trawl. Throughout years of investigations of the coastal and open Adriatic, the species Cymatium corrugatum has been recorded only in the vicinity of the Vis and Hvar islands, at 60 and 80 m depths. It was found in the biocoenosis of detritic bottoms of the open sea and biocoenosis of coastal detritic bottoms. Cymatium corrugatum is a new species for the Adriatic and therefore it should be included in the register of the Gastropod fauna of the Adriatic Sea.

Die Besiedlung innerstädtischer Grünflächen Greifswalds durch Kurzflügeldecken-Käfer (Coleoptera: Staphylinidae)

In 1993 staphylinids of 18 urban habitats in Greifswald were identified and analysed. The beetles were caught by pitfall traps operated from April until October. 10366 individuals from 161 species were found. The habitats subdivide into 3 types: green areas (high frequency of cutting, more than 4 times per year), meadows (less than 4 cuttings per year) and pasture. The relationships between number of species, activity abundance, dominance structure, identity of the inventory of species, parts of different size classes, demands of moisture and the different types of habitat were analysed. Only the staphylinid fauna of green areas is distinctive. The staphylinids of green areas are on average smaller, have a lower number of species and a higher number of xerophil species than meadows and pastures. The staphylinid faunas of meadows and pastures show no significant differences. After analysing the indigenous species, differences between greens with little or no use and greens with medium use were noted. Greens with little or no use are important for reproduction of urban staphylinid beetles. Furthermore, staphylinid beetles were studied for preference for each of the habitat types. Most species were ubiquitous, with Zyras humeralis and Plataraea brunnea being the only species that had a preference for green areas. The occurence of these two species in a large spectrum of habitats does not allow their use as differential species, however. Species with preference of meadows or pasture were not found. In general, it is necessary to increase our knowledge about the ecology of individual species before staphylinids can be used as bioindicators for urban habitats.

The occurrence of thermophilous trees in the Scandes Mountains during the early Holocene: evidence for a diverse tree flora from macroscopic remains

1 Macroscopic remains of the fairly thermophilous tree species Alnus glutinosa, Tilia cordata and Betula pendula were recovered in subalpine and adjacent boreal environments far above and beyond their present‐day distributional limits. This establishes that the early Holocene tree flora of the Scandes Mountains in northern Sweden was indeed richer than it is today. 2 Dates ranged between c. 8600 and 7000 radiocarbon years bp. These are much earlier than previous estimates by conventional pollen stratigraphical analyses of the arrival of these species at their maximum geographical limits. This highlights problems in using only pollen data for vegetation reconstruction, and suggests re‐evaluation of earlier records. 3 The results, together with similar macrofossils for Picea abies and Larix sibirica in northern Sweden, suggest that many tree species spread rapidly and became established at their most extended range limits during the early Holocene. Abundances have subsequently varied in accordance with the ecology of individual species as well as with climatic change. 4 Palaeoclimatic inferences may suggest a strongly continental climate, i.e. warmer and drier summers and possibly fairly cold winters between 8600 and 7000 bp relative to the present. Some change towards a more oceanic climate regime with less pronounced seasonal contrasts may have occurred towards the end of the period.

Living (stained) benthic foraminifera within surficial sediments of the Skagerrak

An analysis of living (stained) benthic foraminifera within four box cores raised from water depths of 74 to 621 m in the Skagerrak shows that faunal patterns at different water depths are strikingly different within this relatively shallow, organicrich marginal sea environment. Although some genera show vertical stratification within the sediments, a number of taxa are found over wide intervals or have different patterns between cores. The vertical distributional data are compared with deep-sea data from the eastern margin of North America. Benthic foraminifera from a deep core at 530 m in the Skagerrak have similar faunal patterns within the surficial sediments as found in the deep sea, but shallow cores at 74 and 212 m have more complex patterns. This difference between shallow and deep cores within the Skagerrak and the North Atlantic is attributed to higher biological activity in the shallow environments, which creates a greater amount of heterogeneity within the shallow-water sediments than is found in deeper environments. The faunal data suggest that the use of benthic foraminifera for paleoenvironmental reconstructions in shallow, organicrich regions will be complicated in future studies. The ecology of individual species is difficult to assess because of the complex faunal patterns observed within the surficial sediments. Geochemical studies for estimating bottom water oxygen or organic carbon flux will also be difficult, since these studies assume that taxa occupy particular microhabitats within the surficial sediments.

THE SOIL ALGAL COMMUNITY. II. SOVIET SOIL STUDIES

SUMMARY The enormous quantity of work done in the Soviet Union is inadequately known elsewhere. Soviet generalizations rest on extensive data published in the Russian and Ukranian languages. The primary criterion of community analysis is now the total algal flora, but it is foreseen that the ecology of individual species is a more desirable parameter. Methods of sampling and culture in the Soviet Union are largely the same as those used elsewhere. The basic problems of sampling and quantification have not been solved yet. It is felt that the prerequisite to understanding the Soviet experience is a commonly held taxonomy. Soviet taxonomists are judged as fully competent, but lack communications with outside taxonomists in respect to methodology and references. As a contribution to the common understanding, new identifications of Soviet species (mostly blue‐greens) are included in this paper. These were derived from: a study of moist soil dishes from collections made according to a horizontal distribution plan in a single field; collections from near Leningrad, Middle Asia (Alma‐Ata, Tashkent, Samarkand, Buchara); liquid cultures of soil collected by a Soviet investigator in Kazakistan; and agar cultures of soil algae which are maintained in Soviet laboratories. Also included is a selected bibliography, in English translation, of 71 Soviet publications.