Evaluating monitoring methods to guide adaptive management of a threatened amphibian (Litoria aurea)

Prompt detection of declines in abundance or distribution of populations is critical when managing threatened species that have high population turnover. Population monitoring programs provide the tools necessary to identify and detect decreases in abundance that will threaten the persistence of key populations and should occur in an adaptive management framework which designs monitoring to maximize detection and minimize effort. We monitored a population of Litoria aurea at Sydney Olympic Park over 5 years using mark–recapture, capture encounter, noncapture encounter, auditory, tadpole trapping, and dip‐net surveys. The methods differed in the cost, time, and ability to detect changes in the population. Only capture encounter surveys were able to simultaneously detect a decline in the occupancy, relative abundance, and recruitment of frogs during the surveys. The relative abundance of L. aurea during encounter surveys correlated with the population size obtained from mark–recapture surveys, and the methods were therefore useful for detecting a change in the population. Tadpole trapping and auditory surveys did not predict overall abundance and were therefore not useful in detecting declines. Monitoring regimes should determine optimal survey times to identify periods where populations have the highest detectability. Once this has been achieved, capture encounter surveys provide a cost‐effective method of effectively monitoring trends in occupancy, changes in relative abundance, and detecting recruitment in populations.     

Calling phenology and detectability of a threatened amphibian (Litoria olongburensis) in ephemeral wetlands varies along a latitudinal cline: Implications for management

Amphibian reproductive biology and activity are highly sensitive to environmental cues. For amphibian conservation in the face of climate change, a clear priority is to investigate impacts of variable weather on breeding activity and detectability. This study assessed variation in the phenology, intensity and detectability of calling for a threatened temporary wetland breeding species, Litoria olongburensis. Acoustic and visual surveys were conducted monthly from August 2009 to July 2011 over the species latitudinal range in eastern Australia. Calling phenology of L. olongburensis varied spatially and temporally within and among latitudinal clusters. Detectability of frogs also varied among months and transects, and also with the type of survey conducted (visual vs. acoustic). Air temperature was a strong predictor for the onset of the calling season (early spring); however, peaks in calling abundances were primarily driven by monthly accumulated rainfall. The duration of the calling season varied among latitudinal clusters, becoming narrower moving south, reflecting clinal variation in weather patterns. This study presents a framework for amphibian species management using a combination of survey techniques and the climatic conditions influencing detectability. Applied along the latitudinal gradient, it provides data for predicting the likely impacts of climate change on amphibian activity and reproduction.     

Microsatellite variation and population structure in a declining Australian Hylid Litoria aurea

The green and golden bell frog (Litoria aurea) was once a common Australian Hylid. Today, many populations are small and fragmented as a result of dramatic declines in distribution and abundance. We undertook a large-scale assessment of genetic structure and diversity in L. aurea using four species-specific microsatellite markers. Twenty-one locations were sampled from throughout the species range covering 1000 km of the east coast of Australia. Levels of allelic diversity and heterozygosity were high (uncorrected mean alleles/locus and H(E) were 4.8-8.8 and 0.43-0.8, respectively) compared to other amphibian species and significant differences among sampled sites were recorded. Despite recent population declines, no sites displayed a genetic signature indicative of a population bottleneck. Significant genetic structuring (overall F(ST) 0.172) was detected throughout the species range, but was relatively low compared to previous amphibian studies employing microsatellites. In addition we found that some areas sampled within continuous habitat showed evidence of weak genetic structuring (data subset F(ST) 0.034). We conclude that maintaining areas of continuous habitat is critical to the conservation of the species and argue that population recovery and/or persistence in all areas sampled is possible if appropriate protection and management are afforded.     

Habitat characteristics predict occupancy patterns of the endangered amphibian Litoria raniformis in flow‐regulated flood plain wetlands

Identification of habitat features that are strongly associated with the occurrence of threatened species is important in terms of predicting impacts of habitat change and identifying key habitats for conservation. In this paper, we apply habitat‐based statistical models to predict occupancy patterns of the endangered southern bell frog (Litoria raniformis) across inland New South Wales (Australia). Litoria raniformis previously occupied a wide range of natural and man‐made waterbodies across a large geographic range, including flood plain wetlands, oxbow lagoons, irrigation canals and rice bays. Alteration of natural flooding regimes has affected a large proportion of habitats within the historical range of Litoria raniformis, but it is not clear how these changes have influenced habitat occupancy patterns. Fifty‐two waterbodies were surveyed for presence/absence of Litoria raniformis in 2001 and 2004. Stepwise logistic regression models were generated to select a subset of variables that best predicted occupancy. Using three predictor variables, vacant and occupied habitats could be predicted with an accuracy of 90% and 70%, respectively. The predictor variables were: the interaction between wetland hydrology and complexity of aquatic vegetation, complexity of fringing vegetation and water temperature. While this study demonstrated that a range of waterbody types were occupied by Litoria raniformis, these habitats shared common hydrological conditions and vegetation characteristics. Altered flooding regimes and reductions in the complexity of aquatic and fringing vegetation are likely to increase the probability of localized extinctions of Litoria raniformis populations.     

Fruit size in a tropical tree species: variation,preference by birds,and heritability

Ocotea tenera (Lauraceae), an understory bird-dispersed tree, produces single-seeded fruits that vary in diameter from 1.4 to 2.4 cm. Much of the variation within a population at Monteverde, Costa Rica occurred within individual trees. The relative size of fruits produced by different trees remained generally constant over an 11-year period despite slight differences between years in the average size of fruits produced by a given tree.Fruit-eating birds could thus express their preferences for particular fruit size characteristics by choosing among trees that have distinct distributions of fruit diameters, and between individually variable fruits within trees. In a field study of individually marked fruits, birds removed 46.2% of fruits; the rest of the fruits were destroyed by invertebrate (25.3%) and vertebrate (4.3%) pulp-feeders or aborted by the plant after remaining ripe but uneaten for as long as 100 days (24.2%). The four major avian seed dispersers of O. tenera each have gape widths exceeding all but the largest fruits. Birds preferred plants with greater-than-average-sized fruits; within trees, they favored larger fruits, apparently because net pulp mass increases with fruit diameter. Fruits that ripened early in the season were more likely to be removed and were removed more quickly than late-ripening fruits.Based on mother-offspring regressions of mean fruit size, the phenotypic variation in fruit diameter in O. tenera is highly heritable, indicating the potential for an evolutionary response to selection by birds. Nonetheless, directional selection on fruit size or shape is likely to be inconsistent, constrained by genetic correlations, and weak compared to selection on traits like fecundity or phenology.     

Life history comparisons of Daphnia obtusa from temporary ponds, cultured with a low-quality food

Temporary pond Daphnia flourish on relatively poor-quality food, suggesting adaptation to stringent temporary pond conditions. We conducted laboratory life history experiments on populations of Daphnia obtusa from a shaded woodland temporary pond (short hydroperiod, dystrophic) and an open farmland temporary pond (long hydroperiod, eutrophic), and compared a suite of physical/chemical conditions in the ponds to evaluate habitat conditions. We hypothesized that the shaded woodland pond population would be more fit in terms of life history variables for individuals (age and size at first reproduction, mean brood size, mean number of neonates) and populations (generation time, net reproductive rate R ₀, and intrinsic reproductive rate r) given a standard, low-quality food (trout chow and yeast). Life history traits of woodland pond animals were mixed, relative to farm pond animals, and consistent with bet-hedging for an unpredictable habitat. Values of life history traits rivaled or exceeded those of other studies using phytoplankton as food, and were influenced by the pond water used for our study. Life histories clearly differ among local and regional temporary pond Daphnia obtusa populations, and should be valuable for examining the relative influences of local selection and metapopulation dynamics on population structure.     

The effect of aquatic and terrestrial habitat characteristics on occurrence and breeding probability in a montane amphibian: insights from a spatially explicit multistate occupancy model

Understanding species distribution and predicting range shifts are major goals of ecology and biogeography. Obtaining reliable predictions of how species distribution might change in response to habitat change requires knowledge of habitat availability, occupancy, use for breeding, and spatial autocorrelation in these parameters. Amphibians in alpine areas provide an excellent model system for disentangling habitat drivers of occupancy from that of breeding while explicitly accounting for spatial autocorrelation. We focused on the widespread common frog (Rana temporaria) inhabiting alpine lakes in the Southern Carpathians, Romania. We used single season multistate occupancy models developed to account for imperfect detection and spatial autocorrelation to estimate the occupancy and breeding probabilities and to evaluate their response to habitat characteristics. We found that frogs do not occur in all water bodies [occupancy probability: 0.697; 95% credible interval (0.614, 0.729)] and do not breed in a substantial proportion of water bodies where they occur [breeding probability conditional on occupancy: 0.707; 95% credible interval (0.670, 0.729)]. Habitat characteristics explain water body occupancy but not breeding probability; and altitude, water body surface area, water body sinuosity and permanency, presence of invertebrates, and grazing along the banks all had positive effects on occupancy. We also detected strong spatial autocorrelation in occupancy and breeding probabilities. Thus, our results indicate that habitat choice by montane amphibians is influenced by both spatial autocorrelation and habitat characteristics. Because spatial autocorrelations matter and because the presence of adults is not the same as the presence of a reproducing population, it will be difficult to predict the effects of habitat change on high altitude amphibian populations.     

The life history and decline of the threatened Australian frog,Litoria raniformis

A popular idea amongst ecologists last century was that animals which exploit dynamic environments often display ‘fast’ life history strategies (high fecundity, rapid growth and maturation, and low or variable adult survival rates) relative to those which occupy more stable environments. Whilst the underlying theory has been discredited, the categorization remains of interest, because species with ‘fast’ life history traits are thought to be more robust to human‐induced environmental change than those with ‘slow’ life history traits. We examined the life history traits of the endangered Australian frog Litoria raniformis, to determine whether it displays ‘fast’ life history traits (like its sister species L. aurea and L. castanea), and to assess the role of these traits in the decline of this species. Mark‐recapture data confirmed that L. raniformis displays rapid growth and maturation. The data also suggest that L. raniformis displays relatively low adult survival rates. We propose that the ‘fast’ life history traits of this species are adaptive to metapopulation dynamics. In turn, we suggest that the rapid decline of L. raniformis may have resulted from metapopulation collapse, driven ultimately by habitat loss, degradation and fragmentation, and proximately by severe stochastic perturbations.     

On the occurrence of the Asiatic cyprinid Pseudorasbora parva in the Netherlands

A large scale inventory along the Meuse River (the Netherlands), showed that floodplain lakes function as spawning, nursery and adult habitats, while the main river channel merely serves as a dispersal corridor for adult Pseudorasbora parva , one of the most successful invasive fish species that have colonized Europe.     

Determination of age, longevity and age at reproduction of the frogMicrohyla ornata by skeletochronology

Skeletochronological estimation of age, longevity, age at sexual maturity and breeding of Microhyla ornata was done. Frogs (n=62) were collected locally in August (rainy season) 1997 and brought to the laboratory. Body mass and snout-vent-length (SVL) of each frog was recorded; the 4th toe of both the hind limbs was clipped under anaesthesia, fixed in 10% formalin, demineralized in 5% nitric acid and processed for histology. Limb bones (femur, humerus, tibiofibula and radioulna) of 6 large sized frogs were also processed for skeletochronology in order to study the rate of resorption. Gonads of 25 frogs (belonging to different body size ranges) were processed for histology in order to ascertain the gametogenic status of individual frogs. One to four growth rings consisting of growth zones and lines of arrested growth (LAGs) were noticed in frogs of different body sizes; the number of LAGs remained identical in all the limb bones and phalanges in 5 out of 6 frogs. Back calculation indicated that the resorption rate is very low in this frog. Male frogs possessed sperm bundles in seminiferous tubules in the 1st year, while females showed yolky follicles in the ovary in the 2nd year. Frogs found in amplexus were 3 5 years old. The results suggest that this frog may live for a maximum of 5 years in the natural population.     

秦岭大熊猫种群扩散格局及研究方法

种群扩散格局是研究种群扩散规律和机制的关键信息,也是制定物种保护对策的重要基础。大型动物种群扩散格局研究方法为扩散生态学研究的薄弱领域,并制约扩散生态学的发展。以秦岭大熊猫为研究对象,根据2000年以来的种群调查数据,基于大熊猫领域的特性,利用GIS的扩展区分析功能和景观分析方法研究了大熊猫种群分布区及动态;基于聚集的特性,利用GIS的核密度分析功能对大熊猫种群多度和聚集状况及空间变化进行了分析。发现2012年的秦岭大熊猫种群分布区较2000年增加5.5%(即15307.8hm~2),高密度种群聚集区从2处变成1处,种群聚集程度进一步增加、聚集格局的完整性大大提升,尤以中密度聚集区增长最显著,种群格局呈明显的分布区扩张、聚集度增加的态势。表明基于物种的生物学特性,立足于种群分布和多度格局变化,通过长期调查和监测可以有效掌握物种的种群扩散格局;大型动物可根据其生物学特性探索可行的方法与量化种群扩散的参数来研究其扩散格局,从而促进大型动物种群扩散研究的开展。     

Reproductive mode and genetic variation suggest a North American origin of European Letharia vulpina

Our data on the intercontinental population biology of Letharia vulpina show an unexpected shift from a recombining North American population with unique haplotypes to genetically depauperate Swedish and Italian populations, each with many representatives of a single repeated haplotype. Analysis of eight loci in 47 individuals supported recombination in North American populations and showed almost no variation among European populations. We infer that a genetic bottleneck caused by limited long-distance dispersal accounts for the lack of genetic variation found in marginal populations. This lack of variation in the European populations makes it impossible to use population genetic means to distinguish clonal reproduction from self-fertilization or even outcrossing, but phenotype indicates that reproduction in the marginal populations is by clonal spread, via soredia and isidioid soredia.     

Effects of landscape and history on diversification of a montane, stream-breeding amphibian

Aim The aim of this study was to understand the roles of landscape features in shaping patterns of contemporary and historical genetic diversification among populations of the Andean tree frog (Hypsiboas andinus) across spatial scales. Location Andes mountains, north‐western Argentina, South America. Methods Mitochondrial DNA control region sequences were utilized to assess genetic differentiation among populations and calculate population pair‐wise genetic distances. Three models of movement, namely traditional straight‐line distance and two effective distances based on habitat classification, were examined to determine which of these explained the most variation in pair‐wise population genetic differentiation. The two habitat classifications were based on digital vegetation and hydrology layers that were generated from a 90‐m resolution digital elevation model (DEM) and known relationships between elevation and habitat. Mantel tests were conducted to test for correlations between geographic and genetic distance matrices and to estimate the percentage variation explained by each type of geographic distance. To investigate the location of possible barriers to gene flow, we used Monmonier’s maximum difference algorithm as implemented in barrier 2.2. Results At both geographic scales, effective distances explained more variation in genetic differentiation than did straight‐line distance. The least‐cost distances based on the simple classification performed better than the more detailed habitat classification. We controlled for the effects of historical range fragmentation determined from previous nested clade analyses, and therefore evaluated the effect of different distances on the genetic variation attributable to more recent factors. Effective distances identified populations that were highly divergent as a result of isolation in unsuitable habitats. The proposed locations of barriers to gene flow identified using Monmonier’s maximum difference algorithm corresponded well with earlier analyses and supported findings from our partial Mantel tests. Main conclusions Our results indicate that landscape features have been important in both historical and contemporary genetic structuring of populations of H. andinus at both large and small spatial scales. A landscape genetic perspective offers novel insights not provided by traditional phylogeographic studies: (1) effective distances can better explain patterns of differentiation in populations, especially in heterogeneous landscapes where barriers to dispersal may be common; and (2) least‐cost path analysis can help to identify corridors of movement between populations that are biologically more realistic.     

Light and electron microscopic analyses of the high deformability of adhesive toe pads in White's tree frog,Litoria caerulea

White's tree frog (Litoria caerulea) has large, adhesive toe pads that are among the softest of all known biological structures. To explore the morphological basis for the physical properties of the toe pads, the internal microstructure of the toe pads in L. caerulea was examined using both light and transmission electron microscopy. Three design elements that are distinct from other areas of skin were observed. First, the keratinocytes comprising the adhesive surface of the toe pad all contained keratin filament bundles (tonofibrils) exhibiting structural anisotropy. Specifically, the curved conformation of the hierarchical (branching) tonofibrils was characterized by the formation of anastomoses consisting of tonofibrils beneath the adhesive cell surface and stem keratin filament bundles concentrated in the lower‐middle part of the dorsal‐side of adhesive cells. Second, the cytoplasm of keratinocytes in the most superficial cell layer contained glycoproteins (stained by periodic acid/Schiff reagent) that are considered to confer high viscoelasticity. Third, the dermis contained large lymph spaces interspersed with elastic fibers and collagen fibers, which were relatively sparsely distributed compared to the dorsal skin of the toe pads. The profiles of these structures were easily deformed by the slight application of pressure. These findings reaffirmed that the unique internal architecture of the toe pads in L. caerulea contributed to their remarkable softness and high deformability, which in turn increased the contact area and provided improved adaptability to the local topography of natural surfaces. J. Morphol. 277:1509–1516, 2016. © 2016 Wiley Periodicals, Inc.     

The capuchin, the howler, and the Caatinga: seed dispersal by monkeys in a threatened Brazilian forest

Regeneration of the Brazilian Caatinga forest may be restricted by the naturally low diversity and density of fruit-eating animals, which has been aggravated by local faunal extinction induced by human activities. We made a preliminary evaluation of the potential seed-dispersal role of capuchin (Cebus apella libidinosus) and howler monkeys (Alouatta caraya) in Serra da Capivara National Park. The monkeys dispersed at least 26 species. Alouatta dispersed larger seeds than Cebus, and the two species apparently dispersed seeds in different local habitats. Seed dispersal by monkeys potentially makes a significant contribution to Caatinga regeneration.     

Highlighting the effects of land-use change on a threatened amphibian in a human-dominated landscape

In Western Europe, habitat loss and landscape fragmentation has led to significant population decline in various animal groups, including amphibians. The extinction of the last natural populations of the yellow-bellied toad in Belgium, Luxembourg and several regions of southern and western France suggests a widespread decline. By using site-occupancy models and adding covariates corresponding to the human-influenced features of the landscape, we tried to identify the relative effects of different land-use types on the species’ distribution pattern in a man-made environment (the Alsatian Rhine floodplain in France). We recorded presence–absence data in 150 forest sample plots (300 × 300 m) and then modeled species distribution while taking into account detection errors in the field. Land-use was recorded on two spatial scales: within the forest sample plots and in a 1500 m radius buffer area around the forest plots. In the forest plots, toad occurrence was negatively correlated with loss of forest cover to agricultural land. In contrast, occurrence is positively correlated with the density of human-made rutted dirt paths and tracks, which provide semi-natural breeding sites. In the 1500 m radius buffer zones around forest plots, toad occurrence was negatively correlated with the density of urbanization and road networks. These results can be used to plan conservation strategies for amphibians in human-dominated landscapes.     

Life history and the evolution of family living in birds

The reason why some bird species live in family groups is an important question of evolutionary biology that remains unanswered. Families arise when young delay the onset of independent reproduction and remain with their parents beyond independence. Explanations for why individuals forgo independent reproduction have hitherto focused on dispersal constraints, such as the absence of high-quality breeding openings. However, while constraints successfully explain within-population dispersal decisions, they fail as an ultimate explanation for variation in family formation across species. Most family-living species are long-lived and recent life-history studies demonstrated that a delayed onset of reproduction can be adaptive in long-lived species. Hence, delayed dispersal and reproduction might be an adaptive life-history decision rather than 'the best of a bad job'. Here, we attempt to provide a predictive framework for the evolution of families by integrating life-history theory into family formation theory. We suggest that longevity favours a delayed onset of reproduction and gives parents the opportunity of a prolonged investment in offspring, an option which is not available for short-lived species. Yet, parents should only prolong their investment in offspring if this increases offspring survival and outweighs the fitness cost that parents incur, which is only possible under ecological conditions, such as a predictable access to resources. We therefore propose that both life-history and ecological factors play a role in determining the evolution of family living across species, yet we suggest different mechanisms than those proposed by previous models.     

Viability analysis of a threatened amphibian population: modelling the past,present and future

Conservation actions that have maintained populations in the past may not necessarily do so in the future. Population viability analysis provides one tool for exploring the impact of management actions on large temporal scales. However, there are relatively few long‐term data sets that provide the demographic and environmental data demanded by such models. Using a 37‐yr data set, we used RAMAS Metapop to model the persistence of natterjack toads Epidalea (Bufo) calamita on a heathland in southern Britain. A retrospective analysis showed that the best fit between the predicted population trajectories and the real population was when the management carried out was modelled as an increase in K of 150 toads yr^?1. However, even if ongoing management continues to improve K by a further 40–60 toads yr^?1 over the next 50 yr, the population still has an extinction risk of at least 60% if other factors remain unchanged. Sensitivity analyses and simulated management scenarios indicated that the population was most sensitive to changes in the survival of juvenile (i.e. 1–2 yr old) toads. In addition, if the frequency and severity of pond desiccation increases, the risk of extinction was predicted to increase as a result of reduced recruitment. Low levels of extinction risk occurred irrespective of K when juvenile survival was enhanced in combination with low frequency and severity of pond desiccation. The models suggest that populations that are responding to management against a background of natural fluctuations may remain vulnerable to extinction for several decades. These extinction risks may increase if habitat management fails to offset reductions in recruitment and juvenile survival caused by environmental change.     

Calcareous sponges of the genera Clathrina and Guancha (Calcinea, Calcarea, Porifera) of Norway (north-east Atlantic) with the description of five new species

The taxonomy and distribution of 11 species of calcareous sponges of the subclass Calcinea from the Norwegian coast are reviewed. The Norwegian Calcinea represents a mixture of southern boreal/boreal and boreoarctic species, and the calcinean sponge fauna of northern Norway has strong similarities to the Greenlandic and the White Sea/Barents Sea sponge faunas. Most Norwegian Calcinea have their main distribution between 20 and 100 m depth, although some species are found only in the shallow sublittoral or from sublittoral to abyssal depths. Six species were previously reported in the area: Clathrina coriacea (Montagu, 1818), Clathrina cribrata Rapp et al ., 2001, Clathrina nanseni (Breitfuss, 1896), Clathrina septentrionalis Rapp et al ., 2001, Guancha blanca Miklucho-Maclay, 1868 and Guancha lacunosa (Johnston, 1842). Five species are new to science: Clathrina corallicola , Clathrina jorunnae , Guancha arnesenae , Guancha camura , and Guancha pellucida spp. nov. A key to the known Norwegian Calcinea is provided.  © 2006 The Linnean Society of London, Zoological Journal of the Linnean Society , 2006, 147 , 331–365.