Comparative tests of ectoparasite species richness in seabirds

Background  

The diversity of parasites attacking a host varies substantially among different host species. Understanding the factors that explain these patterns of parasite diversity is critical to identifying the ecological principles underlying biodiversity. Seabirds (Charadriiformes, Pelecaniformes and Procellariiformes) and their ectoparasitic lice (Insecta: Phthiraptera) are ideal model groups in which to study correlates of parasite species richness. We evaluated the relative importance of morphological (body size, body weight, wingspan, bill length), life-history (longevity, clutch size), ecological (population size, geographical range) and behavioural (diving versus non-diving) variables as predictors of louse diversity on 413 seabird hosts species. Diversity was measured at the level of louse suborder, genus, and species, and uneven sampling of hosts was controlled for using literature citations as a proxy for sampling effort.     

田鼠属动物婚配制度的研究范式

从社会组织的生态格局、熟悉性、社会等级和交配近况等择偶行为的影响因子,性二型和雄性射精能力等个体特征,配对关系的神经内分泌机制几方面综述了田鼠动物婚配制度的研究进展,同时从生态学、比较心理学、生理学、神经生物学等方面探讨择偶行类节式的特点。生态学方法,用鼠动物具有完整的婚配制度多样性格局,是婚配制度比较研究的哺乳动物类群。运用比较心理学方法,通过择偶行为实验可直接比较单配制与较研究的理想哺乳动物类     

Deterministic diversity changes in freshwater phytoplankton in the Yunnan–Guizhou Plateau lakes in China

Diversity measures reflect different aspects of a community, which are determined by different ecological processes. However, information is still limited on the ecological processes that are represented by different measures of species diversity. In this study, the primary driving factors for richness and diversity indices were tested. The possible ecological processes represented by each index were analyzed. First, the type of ecological process that governed the phytoplankton community in the Yunnan–Guizhou Plateau lakes, either deterministic or stochastic, was identified by Caswell's neutral model. The results indicate that a deterministic process governs the phytoplankton community. Second, the driving factors of richness and diversity indices were screened with mixed models. The results suggest that the variation of phytoplankton richness in different lakes or sites was primarily related to bottom-up factors. The variations in evenness and other measures based on the relative abundance were driven by both top-down and bottom-up factors, such as zooplankton biomass, and pH and mean light, respectively. Finally, although the different measures of diversity may respond to specific bottom-up or top-down processes, the responses to the two processes were not independent of each other. These findings will increase our understanding of the relationships between ecological processes and diversity measures for freshwater phytoplankton.     

An ecosystem organization model explaining diversity at an ecosystem level: Coevolution of primary producer and decomposer

Ecological complexity of species interactions and habitat heterogeneity creates and maintains biodiversity at a trophic level in an ecosystem. This biodiversity simultaneously serves as raw material on which selective forces for organizing ecosystems operate. As a result of this organization process, differences in structure and functioning of ecosystems (diversity at ecosystem level) are generated. Although understanding diversity at the ecosystem level has attracted great interest, recent theoretical advances toward this aim have not been fully appreciated yet. Following Higashi et al. (1993), this report presents a theoretical framework that deals with the organization process of an ecosystem as a consequence of the interactions among its biotic components and their modification of ecological traits. Specifically, the ecosystem organization process of a terrestrial ecosystem is analyzed, including primary producers and decomposers. This model sheds new insight into the differences between temperate and tropical forest ecosystems.     

Towards a unifying approach to diversity measures: bridging the gap between the Shannon entropy and Rao's quadratic index

The diversity of a species assemblage has been studied extensively for many decades in relation to its possible connection with ecosystem functioning and organization. In this view most diversity measures, such as Shannon's entropy, rely upon information theory as a basis for the quantification of diversity. Also, traditional diversity measures are computed using species relative abundances and cannot account for the ecological differences between species. Rao first proposed a diversity index, termed quadratic diversity (Q) that incorporates both species relative abundances and pairwise distances between species. Quadratic diversity is traditionally defined as the expected distance between two randomly selected individuals. In this paper, we show that quadratic diversity can be interpreted as the expected conflict among the species of a given assemblage. From this unusual interpretation, it naturally follows that Rao's Q can be related to the Shannon entropy through a generalized version of the Tsallis parametric entropy.     

生态复杂性研究——综述与展望

简要介绍了生态复杂性研究的最新进展与动态,生态复杂性研究的背景及若干重要的概念与方法,生态复杂性指生态系统内不同层次上的结构与功能的多样性,自组织及有序性,生态复杂性研究的显著特征是：它应用复杂的理论,方法和观点来研究生态与进化问题,其研究方法主要有元胞机法和遗传算法,认为生态系统是一个适应复杂系统,处于混沌的边缘或临界态,内部作用是生态系统复杂化,有序化及自组织的主要推动力。     

Ecological integrity of supraspecific taxa and the arctic biota

Some specific features of the development of concepts about integrity (systemic organization) of supraspecific taxa are considered. Several forms of integrity can be distinguished: taxonomic, or genealogical; evolutionary (considering a taxon as a developing system); ecological, or eco-adaptive (manifestation of the properties of a united system in the course of exploring the various conditions and types of environment by the phyletically specified biota). Taxa of different level “behave” as whole units or blocks, forming structural parts of the cenotic and biotic forms of life. The properties of integrity, systemic organization of supraspecific taxa can be displayed by analysis of changes in the structural parameters of the biota related to latitudinal gradients of climatic factors, in phenomena of individualistic distribution, ecological substitution (vicariance) of taxa, and preservation of their ecological functions (adaptive zone) despite the reduced species diversity. The variants of adaptive exploration of high-latitude landscape-zonal conditions are considered using examples from the Arctic flora and fauna.     

Within‐population variation in social strategies characterize the social and mating system of an Australian lizard,Egernia whitii

The lizard genus Egernia has been suggested as an excellent model system for examining the evolution of sociality as it exhibits considerable diversity in social organization both between and within species. To date the majority of work examining the factors responsible for the evolution of sociality within Egernia has advocated a broad scale approach; identifying the social structure of specific species or populations and comparing the degree of sociality between them. However, we argue that significant advancements could also be gained by examining variation in social strategies within populations. Here we integrate a detailed, 3‐year, field‐based examination of social spacing and juvenile dispersal with molecular analyses of paternity to determine the social and mating system of a Tasmanian population of White's skink (Egernia whitii). We show that E. whitii live in small stable family groups consisting of an adult male, his female partner(s), as well as juvenile or sub‐adults individuals. In addition, while the mating system is characterized by considerable genetic monogamy, extra‐pair fertilizations are relatively common, with 34% of litters containing offspring sired by males from outside the social group. We also show that traits related to social organization (social group composition, group size, stability and the level of extra‐pair paternity) vary both between and within individuals. We suggest that ecological factors, such as habitat saturation, quality and availability, play a key role in maintaining between individual variation in social strategies, and that examining these individual level processes will allow us to more clearly understand variation in sociality among species.     

Morphological assembly mechanisms in Neotropical bat assemblages and ensembles within a landscape

Empirical studies on bat assemblages have shown that richness is not appreciably influenced by local processes such as ecological interactions. However, most of these studies have been done in large areas that include high heterogeneity, and they analyse all bat species within such areas, and thus they may be not reflecting local but supra-community conditions. We followed an ecomorphological approach to assess how bat assemblages of species from the families Phyllostomidae and Mormoopidae, and ensembles of frugivorous bats, are assembled in local habitats within a single landscape. We measured the volume of the space defined by wing morphology and quantified the average distance between species within such a volume. Then, we related these measures to local richness. Such relationships were contrasted against relationships with random assemblages to test for statistical differences. At the ensemble level of organization, we found that the frugivorous bat morphological assembly mechanism is different from random patterns, and it corresponds to the volume-increasing model. On the other hand, bat assembly mechanisms may be ubiquitous at the assemblage level, because groups of species coexisting in a local habitat and delimited only by phylogeny include more than one ecological group with no potential to interact. Assembling processes are crucial to an understanding of species diversity in local communities, and ecomorphological analyses are very promising tools that may help in their study.     

Development of an Angiosperm Quality Assessment Index (AQuA-Index) for ecological quality evaluation of Portuguese water bodies—A multi-metric approach

Salt marsh vegetation is one important biological element for establishing the ecological quality status (EQS) while evaluating transitional waters (TW). This intertidal plant community is sensitive to the most important pressures present in estuaries. In this study, an ecological index based multi-metric was established taking into account the species composition and ecological relations in Portuguese salt marsh habitats. During the AQuA-Index elaboration it was found that the parameters that respond better to the variability of ecological conditions present nowadays are the Shannon Diversity Index, the Shannon Maximum Diversity Index, the number of halophytic species, the Margalef Diversity Index and the Pielou Equitability Index. The application of the AQuA-Index index to eight TW systems varying in morphology and pressures, demonstrated that the metric responds to the ecological quality of each system. Also, it showed some advantages in comparison with other approaches, in zones with a relevant proportion of middle and upper marsh and where historical data were not available. This way the AQuA-Index proved to be an efficient Index for ecological quality assessment, using salt marsh vegetation as indicator.     

The relationship between environmental complexity, species diversity and productivity in a natural reconstructed yeast community

Diversity, whether ecological or genetic, is widely believed to be beneficial to the functioning of ecosystems. Although many studies have investigated relationships between environmental complexity, species diversity and ecosystem function, few have examined these factors simultaneously. We propagated combinations of three naturally coexisting yeast species for 200 generations, in environments of increasing complexity represented by combinations of up to eight different carbon sources. We found that competitive ability was transitive, and not related to productivity, which was equal among the species. Species diversity had a positive effect on productivity and overyielding in mixtures was caused primarily by complementation. Environmental complexity and species diversity were positively correlated, though not significantly, and the sole case of coexistence of all three yeasts after 200 generations occurred on a single carbon source, melezitose. Environmental complexity also enhanced productivity, although this relationship failed, for unknown reasons, at the highest level of complexity. Our results suggest that maintaining species diversity contributes to ecosystem productivity, but that the mechanisms responsible for maintaining diversity may not be straightforward.     

Integrated ecosystem health assessment based on eco-exergy theory: A case study of the Jiangsu coastal area

The main objective of ecosystem health management is to preserve the capacity of ecosystems to respond to disturbances and future changes. We proposed a set of ecological indicators for coastal ecosystem health assessment using physical stressors such as total suspended matter, chemical stressors including nutrients and heavy metal pollutants, community structure metrics including species richness, diversity and evenness, and ecosystem level eco-exergy indicators. The results of our case study indicate that the health status of the Jiangsu coastal ecosystem is limited by environmental stressors and factors that affect the community species diversity. The health status of nektonic and benthic communities is reflected by water quality and sediment physicochemical properties, respectively. The results of our case study demonstrate that the integrated ecological health indicator system can provide a comprehensive assessment that corresponds with the current health of coastal ecosystems and a reliable theoretical basis for regional coastal management.     

Emergence of community structure in terrestrial mammal-dominated ecosystems

We present a paper that combines empirical and theoretical research about the trophic organization of biological communities. Some regularities are observed in the analysis of the relationship between the trophic structure (how the species are distributed among a set of feeding groups) of a number of African large mammal communities and the type of ecosystem. Different types of ecosystems are characterized by specific patterns in the trophic structure of the mammal community. In order to explain the origin of these patterns, we propose a model defining the underlying dynamic of mammal-dominated ecosystems. The main aim of this study is to show that it is possible to obtain a dynamic explanation of those patterns. The model is shown to spontaneously define different types of structures in community organization, related to those observed. We propose a model that could help to explain the correlation between different environmental factors and the abundance or diversity of herbivores, and which establishes a general mechanism that makes it possible to understand how some rules constrain the assembly of the communities. In addition, the proposed model leads us to see how biological communities can operate in an integrated way, which allows for the acceptance of their changes on large time-scales as evolutionary. In summary, we suggest that communities are unitary structures with coherent properties that result from the self-organizing dynamic of the whole system.     

Wave stress and coral community structure in Hawaii

Summary The most significant factor determining the structure of Hawaiian reef coral communities is physical disturbance from waves. Sequential analysis of community structure off the west coast of the island of Hawaii shows that variation of wave energy and storm frequency clearly affects organization in time and space. Normal conditions of low wave stress maintain four well-defined reef zones; diversity is highest at intermediate depths and decreases in physically rigorous shallow areas and stable deep reef slopes. Intermediate level storm wave events cause variable effects within the reef zones, but the zonation pattern, as a whole, is maintained. Diversity increases in zones that are dominated by a single species largely through nonlethal fragmentation and transport, but decreases in the zone of most equitable species distribution. Conversely, severe infrequent storm disturbances that cause massive mortality to all coral species wipe out the pattern of community structure and return the entire community to a low diversity early successional stage.Hawaii Institute of Marine Biology Contribution No.616     

Allozyme diversity in endemic flowering plant species of the Juan Fernandez Archipelago, Chile: ecological and historical factors with implications for conservation

The level and apportionment of allozyme diversity were determined for 29 endemic (and 1 native) species from the Juan Fernández Islands, Chile. Mean diversities at the species level (H(es) = 0.065) are low but comparable to those measured for other insular endemics in the Pacific. A high mean proportion (0.338) of species-level diversity resides among populations. Diversity statistics were compared for species in different ecological-life history trait categories and abundance classes. Species occurring in large populations and those present in scattered small populations have higher diversities than species occurring in one or two populations. Although not significant with the conservative statistical test employed, lower diversity was found in highly selfing species as compared to animal- or wind-pollinated species. The apportionment of genetic diversity within and among populations (G(ST) values) is not significantly different for any of the species categories. Of particular interest is the lack of difference between animal- and wind-pollinated species because previous analyses of large data sets showed higher differentiation between populations of animal- than wind-pollinated species. Historical factors, both ecological and phylogenetic in nature, can influence the level and apportionment of diversity within insular endemics, and thus ecological correlates of diversity seen in many continental species may not apply to endemics. The results have several conservation implications. The preservation of large populations or several small populations is important for conserving diversity within species because when species are reduced to one or two populations, allozyme diversity is sharply reduced. High mean G(ST) values for the species examined illustrate the need for conserving as many populations as possible, either in the wild or in the garden, to preserve maximal diversity within species. Effective conservation strategies require empirical knowledge of each species.     

Stand and neighbourhood parameters as determinants of plant species richness in a managed forest

Abstract. Patterns of species richness in a managed forest were related to ecological factors at two spatial scales. Local variables within a plot (5 m × 5 m) included 13 soil classes and nine stand classes. Neighbourhood variables were defined within a 25 m radius from the focal plot and were measured using a Neighbourhood Diversity Index (NDI - total diversity of different stand classes) and nine Neighbourhood Scores (NS - relative dominance of a given stand class). 224 species were registered in the survey of which 138 were true forest species. Local parameters (stand and soil class) were weak predictors of total and forest species richness. High total and forest species richness were significantly related to high values of NDI (i.e. heterogeneous neighbourhoods). Regression trees showed that total species richness was best predicted by the amount of roadside habitat in the neighbourhood and NDI. Forest species richness was positively related to NDI and negatively related to the amount of coniferous stands in the neighbourhood.     

Effects of local negative feedbacks on the evolution of species within metacommunities

Local negative feedbacks occur when the occupation of a site by a species decreases the subsequent fitness of related individuals compared to potential competitors. Such negative feedbacks can enhance diversity by changing the spatial structure of the environment. The conditions, however, involve dispersive, environmental and evolutionary processes in complex interactive ways. We introduce a model that accounts for four mechanisms: colonisation‐competition‐extinction ecological dynamics, evolutionary dynamics, local negative feedbacks and environmental averaging. Three qualitatively distinct dynamics are possible, one dominated by specialists, another dominated by generalists and an intermediate situation exhibiting taxon cycles. We discuss how metacommunity diversity, macro‐ecological patterns and environmental patterning are linked to the three qualitative dynamics. The model provides classical shapes for morph‐abundance distributions, or diversity‐area relationships. Diversity can be high when specialists dominate or when taxon cycles happen. Finally, local negative feedbacks often yield fine‐grain environments for taxon cycle dynamics and coarse‐grain environments when generalists dominate.     

Diversity of Tiphiidae (Insecta: Hymenoptera) in the fragmented Brazilian semi-deciduous Atlantic Forest

The Atlantic Forest is one of the most important areas of biodiversity in the world, but it has been largely replaced with agropastoral areas and at the present only 12.5 % of the original cover remains. Despite the ecological importance of insects, few studies have been used in conservation approaches for the Atlantic Forest, mainly due to a great taxonomic impediment. A group quite ecologically important but deeply neglected includes parasitoid wasps that control a great number of invertebrates, like tiphiid wasps that are parasitoids of underground coleopteran larvae. The present study aimed to estimate Tiphiidae species richness and diversity in 15 patches of a highly fragmented Atlantic Forest region, using factors that drive the diversity pool from a metacommunity, such as immigration and speciation probabilities. The parameters were estimated using the Neutral Biodiversity Theory, which is based on the total ecological equivalence of species at the same trophic level. Diversity values were molded to the area size, the immigration probabilities, and/or the speciation probability. Eight genera and 460 individuals of Thynninae, Myzininae and Tiphiinae were collected. Variation in species richness, estimated by both rarefaction and first-order jackknife methods, was explained by patch size and by immigration and speciation probabilities. These variables also explained the variation in Shannon diversity and species evenness. Variations in species richness and diversity of Tiphiidae are strongly associated with neutral processes, but they are also influenced by forest fragmentation and intensive agricultural activities.     

Conservation goals and fisheries management units for Atlantic salmon in the Baltic Sea area

The effective application of genetic information in fisheries management strategies implies political goal setting taking both conservation and fisheries management into account. The concept of sustainable use as set out by the Convention on Biological Diversity offers a valuable starting point in this respect, since the criterion for it is defined as the maintenance of genetic diversity within each species. However, strategic decisions are also needed on the practical level, where the actual genetic information can be taken into account. Genetic factors, such as glacial differentiation, the postglacial genetic structure of populations, gene flow levels and the probability of the existence of adaptive differences, have an effect on the formation of conservation and management units and on the long-term strategy for the sustainable use of aspecies. The Atlantic salmon ( Salmo salar ) in the Baltic Sea area is treated here as an example of a complicated management problem with a highly hierarchical genetic structure associated with marked loss of naturally reproductive stocks, extensive hatchery production and an effective international offshore fishery. The implications of genetic factors for the conservation and management strategy of the Baltic salmon is discussed in the light of the goals set by the Convention on Biological Diversity, the Straddling Fish Stocks and Highly Migratory Fish Stocks Agreement, the Habitats Directive of the European Union and the International Baltic Sea Fishery Commission.     

Consumer vs environmental productivity control of bacterial diversity and bacteria-mediated organic matter decomposition

We experimentally investigated the determinants (consumer vs environmental productivity) and functional consequences of bacterial diversity using a simple laboratory bacterial assemblage and the bacterivorous ciliated protist Colpidium striatum . A two-way factorial design was used, with two productivity levels crossed with the presence/absence of Colpidium striatum . The effects of productivity and predation on bacterial diversity were similar to those previously reported for plant diversity in systems characterized by high productivities, with increased productivity reducing diversity and predation increasing diversity. When Colpidium was present, changes in trophic level biomass and individual bacterial species abundance in response to increased productivity were largely consistent with the keystone predation model. Importantly, Colpidium predation also resulted in an increase in particulate organic matter decomposition, largely due to an increase in the abundance of one single bacterial species that appeared resistant to predation. These results suggest that changes in community structure as a result of trophic interactions and other factors may have profound consequences for important ecosystem functions. We suggest that future research should take an integrative approach and study causes and consequences of biodiversity simultaneously.