Comparative Genetic Structure of the Threatened Tenebrionid Beetle Oplocephala haemorrhoidalis and its Common Relative Bolitophagus reticulatus

We used RAPD and allozyme genetic markers to compare the genetic structures of a threatened saproxylic tenebrionid beetle, Oplocephala haemorrhoidalis, and its common relative (different subfamilies), Bolitophagus reticulatus, to evaluate the relative importance of habitat fragmentation on the occurrence of the two species. O. haemorrhoidalis showed significantly higher levels of genetic differentiation between sites than B. reticulatus for both types of genetic marker. Patterns of isolation by distance were consistent with (B. reticulatus) or close to (O. haemorrhoidalis) theoretical expectations for equilibrium between gene flow and genetic drift. For O. haemorrhoidalis, the RAPD-patterns also showed a steeper increase in isolation by distance where geographic distances were small than at larger distances. This suggests that gene flow between the populations of O. haemorrhoidalis has declined as an effect of recent habitat fragmentation and is probably relatively restricted at present. For B. reticulatus, levels of genetic differentiation were low, suggesting that B. reticulatus readily moves over large areas. Genetic variability was not low in either species. Genetic differentiation among and relatedness within fruiting bodies varied substantially within sites for both species. This variation was probably due to founder events: when levels of relatedness were close to zero, genetic differentiation was also low.     

The saproxylic beetle Bolitophagus reticulatus: its frequency in managed forests, attraction to volatiles and flight period

Reduction in amount of dead trees in Scandinavian forests due to intensive forest management has aroused interest in the requirements of saproxylic (wood-living) species. Much attention has been focused on Bolitophagus reticulatus , a tenebrionid beetle that lives on polypore fruiting bodies of Fomes fomentarius . Although earlier studies have suggested that the species has limited dispersal abilities, the beetle is abundant and widely distributed in Swedish forests. To resolve this paradox we conducted a series of field experiments. Firstly, the frequency of the species was found to be similar in six forest stands with a low density of fruiting bodies and six stands with a high density. Secondly, flying individuals were caught in window traps placed in all of eight randomly chosen, well-managed pine stands. Thirdly, we tested volatiles that flying beetles may use to find hosts by baiting window traps. We found strong attractions to ethanol and to a combination of ethanol and fruiting body. The dispersal period was almost entirely restricted to one week during the summer. Our results suggest that B. reticulatus is distributed wherever the host occurs. Long distance dispersal of B. reticulatus is difficult to observe, but appears to be effective when it does occur. Previously observed patchy distribution patterns of the species are probably due to short-distance movements being more frequent than long-distance movements. A general conclusion is that interpretations based on mark-recapture data and indirect measures of substrate and beetle occurrences that claims limited dispersal should be treated with caution.     

The importance of scale and spatial variables for the fungivorous beetle Bolitophagus reticulatus (Coleoptera, Tenebrionidae) in a fragmented forest landscape

Effects of isolation, habitat size and several microhabitat variables on presence/absence of the monophagous Bolitophagus reticulatus (L.) (Coleoptera. Tenebrionidae) were investigated in 58 forest fragments in an agricultural landscape (15 km²) in south-eastern Norway, All potential habitats of the beetle, dead Fomes fomentarius (L,) Kiekx basidiocarps (n = 587), were collected from trees (n = l85) within the study area. The basidiocarps were dissected and the number of B, reticulatus specimens (larvae, pupae and adults) counted. The material was analysed at four distinguishable spatial scales; basidiocarp-. tree-, tree-group- and forest island level. Different patterns of beetle presence emerged at the different scales, increasing habitat size and decreasing degree of isolation increased the probability of B, reticulatus presence at three (basidiocarp-, tree- and forest island level) and one (tree level) scales, respectively, whilst no such trends were found at the fourth level (tree-group level). Increasing insolation and thereby higher ambient temperatures, indicated by several microhabitat variables, improved the probability of beetle presence amongst the trees. The number of beetle specimens correlated positively with an increase in the habitat size at the tree level.     

Polyploid cytotypes and their habitat preferences inLycopodium clavatum

Morphological, cytological and ecological observations were made onLycopodium clavatum. Among 121 individuals from 26 populations studied 31 were of the diploid cytotype with 2n=68, 45 were of the triploid cytotype with 2n=102 and 45 were of the tetraploid cytotype with 2n=136. The populations were divided into three types: (1) the sole type—characterized by a single cytotype occupying an entire population, (2) the mixed type A—characterized by two or three cytotypes occupying together the same population, but each cytotype choosing different habitats, (3) the mixed type B—characterized by two or three cytotypes occupying together the same population and sharing the same habitat with each other. The mixed type B populations were found in the places of the early phase of secondary succession in a plant community. In the sole type and the mixed type A, the habitat preference for each cytotype was described as follows: the habitat for the diploid was in humid and shady places, that for the tetraploid was in open and sunny, unstable places, and that for the triploid was intermediate between the other two. Each cytotype can progress towards occupying their optimum habitat successively from the mixed type B population to the mixed type A population and finally reaching the sole type population.     

The effect of natal experience on habitat preferences

Several important problems in ecology, evolution and conservation biology are affected by habitat selection in dispersing animals. Experience in the natal habitat has long been considered a potential source of variation in the habitat preferences displayed when dispersers select a post-dispersal habitat. However, the taxonomic breadth of this phenomenon is underappreciated, in part because partially overlapping, taxon-specific definitions in the literature have discouraged communication. Here, we explore the phenomenon of natal habitat preference induction (NHPI) and demonstrate that NHPI has been observed in a broad range of animal taxa. We consider the potential adaptive significance of NHPI, identify implications of its occurrence for problems in evolution, ecology and conservation biology, and encourage further study of this phenomenon.     

Modelling the habitat preferences of preadult and adult fishes on the shoreline of the large, lowland Elbe River

From the years 1997 to 2000, fish assemblages from 15 groyne fields and training walls (a current guiding dyke, protecting the groyne field) of the Middle Elbe River (Germany) were examined by electrofishing. The aim of the study was to detect abiotic environmental key variables which determine preadult and adult fish assemblage in typical riverbank structures using multivariate ordination techniques (canonical correspondence analysis) and univariate methods (logistic regression analysis). Habitat preferences of preadult and adult stages of selected fish species were also estimated. Fish sampling was carried out at 190 river stretches; a further 1615 samples were taken by the point‐abundance sampling method. In total, 21 732 preadult and adult individuals belonging to 30 fish species were caught; perch, eel, ide, roach, chub, gudgeon, bleak and white bream were the most frequent. Eurytopic species clearly dominated the fish assemblage with 72% total abundance, followed by rheophilic species (26%). Limnophilic fish species (rudd, crucian carp, stickleback and tench) were relatively rare (2% of total abundance), with frequencies of occurrence between 1 and 10%. The highest species diversities were estimated in structurally diverse training walls and groyne fields with defective groynes, whereas low species diversity was found to occur in poorly structured, strongly silted groyne fields with intact groynes. Additionally, typical seasonal and annual changes of the fish assemblage were observed. From the mesoscalic point of view, the structure of the preadult and adult fish assemblage was affected by both spatial (type of groyne field, river stretch) and temporal factors (year, season). Regarding the microhabitat, hydromorphological parameters (slope, current velocity, water level, predominant and secondary substrate) followed by physicochemical water values [dissolved oxygen (DO), temperature and pH‐value] are of significance for the structure of the fish community. Furthermore, hiding places (shelter) are of subordinate but significant importance for the fish assemblage in the poorly structured main channel of the Elbe River. Importance of hydromorphological factors on the microhabitat scale was confirmed by multiple logistic regression in 12 of 14 preference models, conducted for different ontogenetic stages of roach, bream, white bream, bleak, ide, chub, gudgeon, asp, perch and eel. Habitat preferences of adult bleak and preadult roach were first determined by physicochemical water values and seasonal influences. Univariate models were generated to describe specific habitat preferences of different species and age‐stages regarding the most important environmental variables (depth, velocity, predominant substrate, slope and shelter). Intraspecific differences were noticed between preadult and adult chub regarding preferences for water velocity, or between preadult and adult perch concerning slope of shore. Interspecific differences were observed, e.g. between adult roach and white bream, with regard to the use of shelters.     

Identifying and understanding ecological preferences for habitat or prey

Patchy, non-random associations of species with habitats and of consumers with particular types of food are commonly found in the ecological literature. In many cases, these patterns are reported to show some preference by an animal making choices about its environment. Generally, however, what is reported is simply the pattern of association and the process that gives rise to this pattern is not further examined. Nevertheless, there are numerous concepts that need to be considered simply to demonstrate the pattern, including the spatial and temporal scales at which the observations are made. When animals make choices between two objects, it is difficult to separate out potential negative, neutral or positive responses to either or both of the objects, without well thought-out manipulative experiments. Apparent preference for food may be influenced by “catchability” or “acceptability” of the prey and/or the past history of the consumer and the experiments to separate these effects are naturally complex. Many experiments examining preferences are beset by problems of non-independence and lack of appropriate controls, which makes them difficult to interpret. This review introduces some of the logical, conceptual, experimental and statistical problems that beset many studies of preference and proposes important steps that must be considered in further studies to unravel this fascinating topic.     

Physical and biological variables related to habitat preferences of rodents

This study determined habitat characteristics related to the presence of species of rodents and possible associations between pairs of these species that may affect their distribution. The study was conducted in the southern half of the Baja California Peninsula, Mexico. We used an environmentally constrained null model with 200 data sites that were sampled from 1999 to 2004 and measurements of different environmental factors obtained from electronic maps, meteorological stations, and measurements in the field. Although most of the isolated factors were not adequate for distinguishing between sites (rodents’ habitat), the combination of all the factors gave an acceptable explanation for the presence of rodent species. The low selectivity of the species for the variables used in the model could be related to the selection of variables that were not appropriate for all species and because an artifact of scale of several variables was employed in the analysis. The percentage of rock cover and vegetation types was most closely related to habitat preference for most species. The possible associations between pairs of these species shown by the null model, the negative interaction between two pairs of species (Peromyscus eva vs. P. fraterculus and Chaetodipus spinatus vs. C. fallax) have probably affected the distribution of these rodents.     

Fish habitat preferences in large streams of southern France

1. Relationships between fish and their habitat over whole geographic regions, which are evident from studies of many streams and species, can improve understanding of lotic communities and provide reliable management tools. Nevertheless, most habitat preference studies have been based on single sites, and confined to small streams and to game species.
2. Regional habitat preference models, based on local velocity, depth and roughness, were developed for twenty-four species and their size classes commonly found in large European streams. Fish surveys were conducted in six large streams in southern France over an 8-year period. To limit the influences of habitat variables other than those studied, we estimated fish preferences within each survey and averaged this information across surveys. Preferences were fitted with confidence intervals and their sensitivity to field uncertainty was evaluated.
3. Most species and size classes had significant preferences for local habitat conditions which were consistent across the region. Habitat preferences predominant in the region overall were not always observed at any one site, but habitat conditions preferred on average in the region were never actually avoided locally. These results support the use of regional preference models for fish and the development of similar models for other lotic groups whose sensitivity to local habitat conditions has been reported elsewhere.     

青斑蝶Tirumala limniace成虫颜色偏好性研究

【目的】明确青斑蝶Tirumala limniace雌、雄成虫对颜色的偏好性,可以为此蝴蝶人工饲养时的合理环境条件设定提供必要的理论支持。【方法】本研究通过在室内和野外对青斑蝶成虫对6种颜色(白色、红色、绿色、黄色、蓝色和紫色)光源的选择行为进行观察,明确青斑蝶成虫对不同颜色的偏好性。【结果】(1)在室内和在野外雌、雄成虫均优先选择黄色。(2)雌雄成虫在野外无其它光源干扰下对黄色的选择性强于室内。(3)单色光源照明和多种不同颜色光源同时存在下,成虫对颜色的偏好程度存在差异:当只有单色光源照明时,成虫对颜色的偏好程度为黄色>绿色=红色≥蓝色≥紫色;当不同颜色光源同时存在时,成虫对颜色的偏好程度则为黄色>蓝色≥绿色=红色≥紫色。(4)在不同颜色光源同时存在时,配对后的雌成虫表现出了比雄成虫更强的颜色选择性:雌成虫对黄色光源的选择性强于雄成虫,且其未产生颜色选择的成虫数量也少于雄成虫。【结论】青斑蝶成虫存在对黄色选择的颜色恒常性,野外成虫对颜色的选择性强于室内,雌、雄成虫对偏好颜色选择性存在性别差异。     

Adaptive habitat preferences in the Tawny Owl Strix aluco

Capsule: Tawny Owls Strix aluco occupying nest boxes preferred habitats which were positively associated with the probability of nesting success.

Aims: We aimed to determine whether or not: (1) Tawny Owls showed habitat preferences when occupying nest boxes; (2) nesting performance was related to the habitats around occupied nest boxes and (3) habitat availability had changed around available and occupied nest boxes between 1995–2004 and 2005–14.

Methods: Tawny Owls were studied using nest boxes erected in a commercial forest. During nest boxes checks (724 cases), data on occupancy and nesting performance (88 cases) were recorded, and habitat within a 0.4?km radius around nest boxes was analysed.

Results: Tawny Owls had preferences for clearings within forests, mature forests and grasslands but avoided young forests. We found a positive relationship between nesting success and abundance of clearings within the forest, and a negative relationship between nesting success and abundance of young forests. A change in habitat preferences over the two decades was evident, but habitat availabilities remained similar.

Conclusions: Findings indicate adaptive habitat selection in Tawny Owls because preferred habitats were associated with higher fitness and this type of habitat became more frequently selected over time.     

Survival of adult Great Tits Parus major in relation to sex and habitat; a comparison of urban and rural populations

Capture-recapture data were obtained for two populations of Great Tits Parus major in southeast Estonia, one rural, the other urban. These data were used to estimate and compare survival probabilities between sexes and populations using capture-recapture statistical models. As is generally assumed, urban birds survived better than rural ones. Females survived better than males, and the survival probabilities varied over time. The three sources of variation considered (sex, habitat and time) had additive effects on survival probability on a logit scale. The estimated annual survival probabilities varied from 0.19 to 0.70. The averages over time ranged from 0.26 to 0.47 and were generally lower than published estimates from other populations. The proportion of yearling breeders was higher among females than among males, contrary to what could have been deduced from survival patterns, and is possibly a consequence of complex recruitment mechanisms.     

Survival and habitat use in translocated and resident greater prairie-chickens

Translocation, or the purposeful movement of organisms from one location to another for conservation, is currently being used to bolster populations of the endangered greater prairie-chicken (Tympanuchus cupido). We used radiotelemetry to compare survival between 58 resident birds and 54 newly translocated greater prairie-chickens that were sourced from a location more than 325 km away. Model averaged survival estimates were lower in translocated birds (0.42; 95% CI: 0.17–0.66) than in resident prairie-chickens (0.65; 95% CI: 0.46–0.79) through the breeding season. Habitat, sex and year were each included in at least 1 of the top 4 models, but the model averaged confidence intervals for each parameter encompassed zero. Survival of both resident and translocated prairie-chickens increased throughout the breeding season. Both translocated and resident prairie-chickens selected for core prairie habitat over agriculture, and birds tended to avoid surrounding private grasslands and wooded areas. We suggest that future translocation projects account for reduced survival of translocated birds when determining the appropriate release cohort sizes and sex ratios. We also recommend that future management for greater prairie-chicken habitat focus on the expansion of core protected patches of prairie to promote elevated survival and better chances of conservation success.     

Host and habitat preferences of polypore fungi in Micronesian tropical flooded forests

The distribution and ecological impacts of plant-associated fungi is determined in large part by their degree of specificity for particular host species or environmental conditions. Here we evaluate the host and habitat preferences among the Aphyllophorales, a guild of wood-decay basidiomycete fungi usually considered to be host generalists. We determined the patterns of host association in three well-defined, floristically distinct, tropical wetlands — freshwater forested wetlands, saltwater mangrove forests, and peatlands with scattered trees — on the islands of Kosrae and Pohnpei in the Federated States of Micronesia. Of 33 fungal species, 20 were locally rare. Of the 11 species sufficiently common to evaluate habitat specificity, nine showed significant habitat preferences. Of eight species common enough to evaluate within-habitat host specificity, six showed strong host preferences. All except one of the nine habitat-specialized fungi showed either statistically significant host specificity or strong numerical biases toward single host species. Our results suggest that host preferences may be important in shaping the assemblages of wood-decay fungi, and that the effect of environment on the distribution of susceptible plant species, rather on the fungi themselves, may ultimately drive the apparent habitat specificity of many fungi.     

Fish distribution and ontogenetic habitat preferences in non-estuarine lagoons and adjacent reefs

We surveyed fish distribution in three lagoons and adjacent forereefs in the British Virgin Islands recording about 28,000 fish from 40 families and 118 species. Canonical correspondence indicated that rock, sand, fleshy algae, gorgonians, mangroves and live hard coral were the most important habitat types influencing fish assemblage composition. About 47% of fishes occurring at more than 10 stations displayed evidence of ontogenetic partitioning between reefs and lagoons but post-settlement ontogenetic life history strategies were quite varied depending on the species. For example Chaetodon striatus juveniles occurred exclusively in lagoons and all sexually mature adults were found on reefs. Some differences were less pronounced as seen in Halichoeres bivittatus where individuals of all sizes occurred on reefs and lagoons, but when analysed it was found that reefs had larger individuals than lagoons. Some species, such as Acanthurus bahianus, were primarily reef species whose juveniles also used lagoon habitats while others, such as Gerres cinereus, were generally lagoon species whose adults occasionally moved onto reefs. Even with all this variation in life-history strategies, all the species that exhibited bay-reef partitioning used the lagoons as juveniles then moved onto reefs as adults and not vice versa, supporting the hypothesis that bays are important nursery areas for reef-dwelling fishes. These results show that a detailed review of the natural life-history strategies and habitat requirements are required before making further generalisations about the role of near-shore habitat types as nurseries for reef fishes. This is especially important given the rapid changes in tropical near-shore habitats around the world.     

Larval habitat preferences of a threatened butterfly species in heavy-metal grasslands

Understanding the factors that determine habitat quality is of vital importance in ensuring appropriate habitat management. Here we used the Niobe fritillary (Argynnis niobe) as a study system to analyse the larval habitat preferences in a small network of heavy-metal grasslands in western Germany. The data were compared with the results of a previous study in coastal dune grasslands of the German North Sea. Based on this knowledge, we give management recommendations for the conservation of this threatened species. The key factors for the survival of A. niobe in heavy-metal grasslands were (i) open vegetation with a warm microclimate and (ii) sufficient host plants for the larvae. This reflects similar results from the previous study in coastal grey dune grasslands. However, in the heavy-metal grasslands, physiological stress generally slows down succession and favours the fritillary’s host plant, the metallophyte Viola calaminaria. As a result, the cover of the host plant was nearly twice as high in heavy-metal grasslands compared to the dune grasslands. Heavy-metal grasslands are of great significance for the conservation of A. niobe and overall butterfly diversity. Usually, the speed of succession in heavy-metal grasslands is slow and, hence, sites with high heavy-metal concentrations are characterised by relatively stable plant composition and vegetation structure. However, on soils with low heavy-metal content a loss of habitats of A. niobe and associated species of conservation concern may occur without management. On those sites sheep grazing seems to be an appropriate way to keep the habitats open and rich in violets.     

Modelling habitat preferences of feral pigs for rooting in lowland rainforest

Feral pigs (Sus scrofa) occupy many different habitats worldwide. Their rooting foraging behaviour poses a serious threat to biodiversity as the resulting soil disturbance alters ecosystem structure and function. Understanding what characteristics are important in selecting rooting locations can be used to predict the impact of pigs on ecosystems. We investigated patch selection for rooting by feral pigs at two spatial scales: (1) habitat variables at a site level, and (2) dependency between observations in a spatial context. Seasonal influences on the modelled environmental variables were also examined. We applied a generalised linear modelling approach and model-averaging to explain the relative importance of variables, as measured by the standardised parameter estimates and unconditional variance. Soil texture, rock cover, soil compaction and sand texture were important explanatory variables in the presence of pig rooting. Soil compaction and distance to roads had a negative influence. The highest ranking model included seven explanatory variables with a 41 % chance that this is the Kullback–Leibler best model. Six of the 128 candidate models were in the 95 % confidence set indicating low model uncertainty. Although no differences in pig rootings were detected between seasons, most rooting (65.7 %) occurred during the dry season with soil and sand texture having the strongest effect. This study highlights how pig control programmes can focus limited resources on either the strategic positioning of control devices (e.g., traps and baits) to either reduce the number of pigs or help prioritise habitats of high conservation value for protection (e.g., exclusion fencing).