Differences In Habitat Preferences Research Articles

Modelling potential habitats for Artemisia sieberi and Artemisia aucheri in Poshtkouh area, central Iran using the maximum entropy model and geostatistics

Predicting potential habitats of endemic species is a suitable method for biodiversity conservation and rehabilitation of rangeland ecosystems. The present study was conducted to estimate the geographic distribution of Artemisia sieberi (A. sieberi) and Artemisia aucheri (A. aucheri), find the most important environmental predictor variables and seek for similarities and differences in habitat preferences between the two species for Poshtkouh rangelands in Central Iran. Maps of environmental variables were created by means of geographic information system (GIS) and geostatistics. Then predictive distribution maps of both species were produced using the maximum entropy modeling technique (Maxent) and presence-only data. Model accuracy is evaluated by using the area under the curve (AUC). Lime1, gravel1, lime 2 and elevation most significantly affect habitat distribution of A. aucheri, while habitat distribution of A. sieberi is affected by elevation, lime1, am1, lime2, and om2. For both species, elevation has an influence on their potential distributions. However, A. aucheri depends more on elevation, and consequently climate in comparison to A. sieberi. Finally, it is revealed that the potential distribution of A. aucheri is limited mostly to mountainous landscapes while A. sieberi is present in wide ranges of environmental conditions.

Habitat Partitioning and Niche Overlap of Two Forest Thrushes in the Southern Appalachian Spruce–Fir Forests

Abstract. Guilds of species that share ecological similarities or recent ancestors are often the basis of studies concerning habitat partitioning. An interesting result of many of these studies is that means of partitioning in one area of sympatry may be different from those in disjunct areas of overlap. Here, we quantified the differences in habitat preference of two forest thrushes in the southern Appalachian Mountains. The Hermit Thrush (Catharus guttatus) has recently expanded its breeding range south along the spine of the Appalachians into the spruce—fir forests of Virginia, North Carolina, and Tennessee. There, it shares breeding habitat with the congeneric Veery (C. fuscescens), previously the only forest thrush breeding in this area. We used several multivariate analyses of habitat variables within both species' territories to understand how these species partition the available habitat and to test if these means of partitioning are similar to those found by other studies. We calculated the niche...

Distribution of cryptic shrew species of the genus Sorex (Mammalia) on the plain between the Don and Kuban rivers as inferred by molecular markers

Microsatellite and mtDNA markers have been used to identify two pairs of cryptic species Sorex araneus L. (Sorex satunini Ogn.) and Sorex minutus L. (S. volnuchini Ogn.). The new data were obtained on the distribution of these species on the plain between the Don and Kuban rivers. The shrew S. volnuchini and Caucasian mole are distributed on the plain areas up to the Eya River. The endemic species of the Caucasus, the shrews S. satunini and S. volnuchini, are widely distributed across the valleys alongside small streams on the steppe plain. Both species are most abundant on thick grasslands, bushy scrub, and deciduous woodlands. They don't show any clear differences in habitat preferences.

Community Ecology of Container Mosquitoes (Diptera: Culicidae) in Virginia Following Invasion by <I>Aedes japonicus</I>

The success of an invasive species in a new region depends on its interactions with ecologically similar resident species. Invasions by disease vector mosquitoes are important as they may have ecological and epidemiological consequences. Potential interactions of a recent invasive mosquito, Aedes japonicus Theobald, with resident species in Virginia were evaluated by sampling larvae from containers and trapping adults. Distinct species compositions were observed for artificial containers and rock pools, with Ae. albopictus most abundant in the former and Ae. japonicus in the latter. However, these two species were found to co-occur in 21.2% of containers sampled. Among the six mosquito species most common in containers from May through September, 2006, only interspecific associations of Ae. japonicus with Aedes albopictus (Skuse) and Aedes triseriatus (Say) were significant, and both were negative. In addition to differences in habitat preference, mean crowding estimates suggest that interspecific repulsion may contribute to the significant negative associations observed between these species. High relative abundances of late instars and pupae of Ae. japonicus seem to provide this species with a mechanism of evading competition with Ae. albopictus, facilitating their coexistence in artificial containers. Although annual fluctuations were observed, trends in adult populations over a 6-yr period provide no evidence of declines. In summary, this survey of diverse container types and all life stages provided only limited evidence for competitive displacements or reductions of resident container species by Ae. japonicus, as observed elsewhere in its invasive range.

Opinion: Habitat data resolution and the detection of species interactions

opinion ISSN 1948-6596 opinion Habitat data resolution and the detection of species interactions In a recent paper, Gotelli et al. (2010) presented evidence for competition structuring in the bird assemblages of Denmark at two spatial scales (5 and 10 km grid cells). They used whole-matrix null models to show that ecologically similar species co-occurred less than expected by chance. As these species had similar habitat preferences they concluded that species interactions must have created the mutually exclusive distributions of the birds. This led them to suggest that species inter- actions should be included in environmental niche models for predicting species occupancy. Whilst the methodology presented in the paper is sound, we have some doubts about the conclusions. As acknowledged by Gotelli et al. (2010), spatially segregated distributions can be formed either by species interactions, e.g., com- petitive exclusion, or by species having distinct habitat preferences. The probability of detecting habitat differences is directly related to the reso- lution of available habitat data; at low resolutions it is unlikely that habitat differences within a guild of similar species will be detected. For example, two species may both live in forests, but if the species require different types of forest they will not overlap. This difference in habitat preference will not be detected unless habitat types are more finely defined than forest . Gotelli et al. (2010) only recognize 12 habitat types in Denmark, but we believe that birds are likely to have more spe- cific habitat preferences. If so, the spatial segrega- tion of species may reflect the distribution of mi- crohabitats rather than competitive interactions. Ecologists are increasingly recognizing that the importance of ecological mechanisms changes according to the scale of observation. Similarly, the apparent importance of species interactions at macroecological scales will be contingent on habi- tat resolution. Broad habitat designations will al- ways overestimate the importance of species in- teractions. However, at fine enough resolutions we are bound to conclude that patterns are due to habitat partitioning. Unfortunately, the only way to truly detect competition is to perform ma- nipulative experiments in the field or lab. Even then it is hard to separate the importance of pre- sent-day competition from the ghost of competi- tion past . Given that manipulative experiments are impossible at large scales, should we consider biological interactions in niche models as pro- posed by Gotelli et al. (2010)? We believe that the resolution of habitat data should influence such decisions. An environmental niche model using coarse habitat designations may indeed need to incorporate species interactions to predict species occupancy. However, a similar model using finer- grained habitat designations may not. Gotelli N.J., Graves G.R., & Rahbek C. (2010) Mac- roecological signals of species interactions in the Danish avifauna. Proceedings of the National Academy of Sciences USA, 107, 5030-5035. Natalie Cooper Department of Ecology and Evolutionary Biol- ogy, Yale University, USA e-mail: natalie.cooper@yale.edu http://pantheon.yale.edu/~nc295/home.html Jonathan Belmaker Department of Ecology and Evolutionary Biol- ogy, Yale University, USA e-mail: jonathan.belmaker@yale.edu http://sites.google.com/site/jonathanbelmaker/ Edited by Frank A. La Sorte Remember that being a member of IBS means you can get free online access to four biogeography journals: Journal of Biogeography, Ecography, Global Ecology and Biogeography and Diversity and Distributions. You can also obtain a 20% discount on the journals Oikos and Journal of Avian Biology. Additional information is available at http://www.biogeography.org/. © 2010 the authors; journal compilation © 2010 The International Biogeography Society — frontiers of biogeography 2.2, 2010

The role of temperature in determining distributions and coexistence of three species of Plestiodon

The Common Five-Lined Skink (Plestiodon fasciatus), Southeastern Five-Lined Skink (P. inexpectatus), and Broadheaded Skink (P. laticeps) are all found in forested ecosystems of the southeastern United States and occur in apparent sympatry. No aspect of their ecology has been quantitatively shown to be different. Differences in their natural history, such as northern extent of geographic range, observations of differences in habitat preference, and differing physiological responses to temperature, implicate the thermal environment as a potential niche dimension by which these organisms partition resources. Here we show that the northernmost extent of each species' range can be adequately discriminated by temperature extremes and that their preferred habitats differ in canopy cover, mean temperature, and daily maximum temperatures. These differences are supported by observations in the field. Based upon these findings and observations, we conclude that these species may be able to exist in such close proximity due to differences in their thermal niche, particularly the two like-sized species, P. fasciatus and P. inexpectatus. P. laticeps is a much larger lizard as an adult and functionally coexists with its congeners, potentially by partitioning resources along a different axis.

Interspecific dominance relationships and hybridization between black-capped and mountain chickadees

Black-capped chickadees (Poecile atricapillus) and mountain chickadees (P. gambeli) are ecologically segregated due to differences in habitat preference. However, forestry practices in northwestern Canada have created a mosaic of coniferous (mountain chickadee habitat) and deciduous forest patches (black-capped habitat), which might explain cases of observed regional sympatry between these 2 closely related species. In Poecile species, social hierarchies amongst conspecific individuals influence lifehistory parameters such as mate choice. As a result, interspecific social hierarchies might drive hybridization between these 2 closely related species. By conducting field observations and aviary experiments, we demonstrated that black-capped chickadees are dominant over mountain chickadees. Using a combination of species-specific phenotypes (plumage), mitochondrial DNA (mtDNA) to assess maternal genotype, and microsatellite markers, we confirmed that genetic mixing occurs within our contact zone but that the pattern of parentage appears directional. All but one of the adult hybrids was phenotypically identified as mountain chickadee and had mountain chickadee mtDNA. Furthermore, all nestlings where microsatellites detected mixedspecies ancestry were from mountain chickadee nests with both attending parents having mountain chickadee phenotypes. All mtDNA from these nestlings was mountain chickadee except for one individual, and in all cases, these nestlings showed genetic patterns of having arisen through extrapair copulations between female mountain and male black-capped chickadees. Our results suggest that hybridization may result from males of the mountain chickadees having lower expression of a preferred trait (dominance) than the black-capped chickadees. Key words: black-capped and mountain chickadees, dominance hierarchies, extrapair paternity, hybridization. [Behav Ecol]

The natural history of mudskippers in northern Australia, with field identification characters

We provide field identification characters and report on the natural history of mudskippers (Gobiidae: Oxudercinae) in Cairns, Darwin, Derby and Broome, northern Australia. Nine species in four genera are recorded (Boleophthalmus birdsongi, B. caeruleomaculatus, Periophthalmodon freycineti, Periophthalmus argentilineatus, P. darwini, P. minutus, P. novaeguineaensis, P. takita and Scartelaos histophorus). The intertidal zonation of mudskippers conforms to previously reported patterns, but subtle differences in habitat preference are observed at both intraspecific and intrageneric levels, underlining the need for in-depth investigation of habitat selection by mudskippers. Although most species inhabit littoral mudflats, some show possible habitat expansion: juvenile Periophthalmodon freycineti are found occasionally in pools on a sandy shore, and a population of Periophthalmus minutus is found to be established in a marginal mangrove habitat (a salt flat behind a pioneer mangrove assemblage). Burrow confinement during high tide is confirmed for both species of Boleophthalmus, two Periophthalmus (P. minutus and P. novaeguineaensis) and Scartelaos, but not for Periophthalmodon or the other Periophthalmus species. Territory formation is described for S. histophorus.

Predicting the environmental niche of the genusPhymaturus: Arepallumaandpatagonicusgroups ecologically differentiated?

AbstractThe genusPhymaturus(Reptilia: Liolaemidae) is distributed in the mountains and rocky plateaux of Argentina and Chile and comprises two groups of species,pallumaandpatagonicus. The two lineages have diverged early in the evolution of the genus and up to today, there is very little geographical overlap between them. We worked with records of localities from the literature, herpetological collections and field data to evaluate habitat suitability of the genusPhymaturus. We used 11 environmental variables to develop environmental niche models (ENMs) for each group within the genus using the Maxent software, and to determine those variables that best explain the distribution of each group. We also estimated measures of niche similarity using ENMTools to determine whether niche differentiation is real or apparent. The geographical overlap between the groups was very low considering the large geographical range of the genus. Some variables, such as mean annual temperature, soil type and bare soil cover, have a high contribution to the models for both groups. The current niche overlap betweenPhymaturusgroups indicates that the environmental niches of thepallumaandpatagonicusgroups are not equivalent. Based on background analysis, we cannot reject the hypothesis that similarity (or divergence) between groups ofPhymaturusis no more than expected based on the availability of habitat. The results of this study are a first approximation to the knowledge of the environmental variables associated with thepallumaandpatagonicusgroups, and reveal that the ecological differences found between these groups are more likely due to habitat availability in their respective regions than to differences in habitat preferences.

Turnover in burrowing rodents: The roles of competition and habitat change

Changes in the burrowing herbivore fauna during the Cenozoic have led to the suggestion that competitive replacement was a driving force in the ecology and evolution of the burrowing herbivore guild. Alternatively, it has been proposed that differences in habitat preferences were associated with the expansion and contraction of the ranges of burrowing herbivores. We examine hypotheses of drivers of mammalian evolution in this guild by looking for evidence of apparent competitive replacements at a regional scale in the middle to late Miocene fossil record of the northern Great Basin. Mylagaulids are most common from 17.5 to 9 Ma, in the Hemingfordian through Clarendonian North American Land Mammal Ages and decline to extinction in the Hemphillian (9 to 5 Ma), at which time the family Geomyidae became more common in this region. In addition to observing this turnover within the guild, we find that geomyids and mylagaulids may occupy different habitats as indicated by evidence from mammalian assemblages and paleopedology. This suggests that mylagaulids and geomyids, rather than competing, may be tracking the extent of their preferred environment. We find no evidence for direct biotic interaction between the members of the guild and suggest instead that the changing abundance of mylagaulids and geomyids in Oregon's Miocene was shaped by habitat partitioning.

Comparison of fibroin cDNAs from webspinning insects: insight into silk formation and function

Embiopterans (webspinning insects) are renowned for their prolific use of silk. These organisms spin silk to construct elaborate networks of tubes in which they live, forage, and reproduce. The silken galleries are essential for protecting these soft-bodied insects from predators and other environmental hazards. Despite the ecological importance of embiopteran silk, very little is known about its constituent proteins. Here, we characterize the silk protein cDNAs from four embiopteran species to better understand the function and evolution of these adaptive molecules. We show that webspinner fibroins (silk proteins) are highly repetitive in sequence and possess several conserved characteristics, despite differences in habitat preferences across species. The most striking similarities are in the codon usage biases of the fibroin genes, particularly in the repetitive regions, as well as sequence conservation of the carboxyl-terminal regions of the fibroins. Based on analyses of the silk genes, we propose hypotheses regarding codon bias and its effect on the translation and replication of these unusual genes. Furthermore, we discuss the significance of specific fibroin motifs to the mechanical and structural characteristics of silk fibers. Lastly, we report that the conservation of webspinner fibroin carboxyl-terminal regions suggests that fiber formation may occur through a mechanism analogous to that found in Lepidoptera. From these results, insight is gained into the tempo and mode of evolution that has shaped embiopteran fibroins.

Traditional and diversified crops in South Moravia (Czech Republic): Habitat preferences of common vole and mice species

Substantial changes in the composition of crops in Central Europe during the last two decades (increasing areas of maize, rape and sunflower fields) have significantly influenced the structure and dynamics of animal communities, though there is a lack of data available for small rodents. In this study, we assessed the importance of these three crops for rodents and compared it with traditional crops (alfalfa, barley, wheat). We observed that herbivorous species (especially the common vole) do not live in crops which do not have green leaves near the ground (e.g. sunflower, maize), while mobile granivorous species can inhabit all types of crop. We confirmed the presumed differences in habitat preferences; however we rejected the hypothesis of a general increase of rodent abundance during the vegetative season in managed fields. We found that (1) maize and sunflower had no importance for common voles, but they were favored habitats for wood mice; (2) numbers of wood mice in rape decreased during the season, while abundances of common voles increased; (3) common vole populations tended to increase during the season in all suitable crops (alfalfa, barley, wheat, tendency in maize and rape); (4) wood mice populations seemed stable in all crops; i.e. without a seasonal increase. It can be concluded that even if the new crop fields are an important part of the agricultural landscape, they are only a temporal habitat for small mammals, especially granivorous species.

Ubiquity of Polynucleobacter necessarius subspecies asymbioticus results from ecological diversification

The subspecies Polynucleobacter necessarius asymbioticus (> 99% 16S rRNA similarity) has a cosmopolitan distribution and a ubiquitous occurrence in lentic freshwater habitats. We tested if the observed ubiquity of these free-living planktonic freshwater bacteria results from a euryoecious (generalist) adaptation of P. n. asymbioticus strains, or from ecological diversification within the subspecies. We developed a reverse line blot hybridization assay enabling the cultivation-independent detection of 13 groups within the subspecies in environmental samples. A set of 121 lentic freshwater habitats, spanning a broad variety of habitat types (e.g. pH levels ranging from 3.8 to 8.5) was investigated for the presence of these 13 P. n. asymbioticus groups. Statistical analyses of the reverse line blot hybridization detections revealed pronounced differences in habitat preferences of several of the groups. Their preferences differed regarding pH, conductivity, dissolved organic carbon and oxygen concentration of habitats. For some groups, differences in environmental preferences resulted even in complete niche separation between them. The revealed differences in habitat preferences suggest that the previously reported ubiquity of P. n. asymbioticus results from ecological diversification within the taxon and not from generalist adaptation of strains.

Habitat preferences and positive assortative mating in an avian hybrid zone

The relatively narrow hybrid zone between hooded and carrion crow is characterised by a high proportion of breeding hybrids, no known intrinsic postzygotic costs, and most likely, high gene flow between populations. It is therefore of interest to identify factors preventing a breakdown of the zone. In this study, we investigate the possibility that habitat choice could create assortative mating in the German–Danish part of the zone. In a GIS analysis, we used two approaches to investigate the role of habitat selection in the maintenance of this zone. We tested if there are 1) any correlations between habitat and the shape of the hybrid zone, and 2) any differences in habitat preferences between territorial individuals of the crow phenotypes. The most extensive habitat, non‐irrigated arable land (Habitat 1), which covers almost 50% of the area in the zone was preferred by all three phenotypes (carrion, hooded and hybrid crows), but showed no change in frequency across the zone. Pastures (Habitat 2) and agricultural areas mixed with natural vegetation (Habitat 4) correlated with the shape of the zone, but only H4 differed in preference between the crow phenotypes. H4 was preferred by hybrids and hooded crows, but not by carrion crows. This habitat is present only in 17% of the hooded crow territories, and thus, it is not likely to have a strong influence on the maintenance of the hybrid zone. There was evidence of assortative mating in pure phenotypes, whereas hybrids showed no consistent mating pattern. Because our GIS analyses suggest that species specific habitat preferences are not involved in shaping the assortativeness, we discuss other possible mechanisms.

Spider Habitat Classification and the Development of Habitat Profiles

The definition of the habitat characteristics of spider species is an essential part of arachnid ecology. In this paper the method of developing habitat profiles from histograms of the number of records of occurrence for each habitat category (Hänggi et al., 1995) has been followed. Those authors used published records from a wide range of sources, mainly in central Europe but also elsewhere. This paper argues that clearer and more precise profiles could be obtained by using data from each individual country so that comparisons of habitat preferences can be made between different geographical regions. The abundant data in the Spider Recording Scheme of the British Arachnological Society (Harvey et al., 2002) make this possible for Britain, but it is not known whether the same amount of information is available in other European countries. An investigation of the latitudinal differences in habitat preferences in Britain was made by dividing the country into three regions: South England, North England and Scotland. A 21-category habitat classification was designed to represent the British landscape. Habitat profiles were prepared for several species in each of the three areas. In most cases habitat differences were recorded. Interpretation of these differences and the possible errors which have to be taken into account are discussed.

Differences in habitat selection of male and female megrim ( Lepidorhombus whiffiagonis, Walbaum) to the west of Ireland. A result of differences in life-history strategies between the sexes?

The sex ratio in the catches of megrim ( Lepidorhombus whiffiagonis, Walbaum) varied systematically with depth on three independent trawl survey series off the west coast of Ireland. Female megrim dominated the shallow catches, while males were more common in catches from deeper waters. The size difference between the sexes alone cannot explain this pattern because it remained evident when fish length was taken into account. Therefore size-specific habitat preferences or size-selective fishing mortality cannot fully explain the observed trend in the sex ratio of megrim. Female megrim grow to a larger size, at a faster rate than males and it is likely that their differences in habitat preferences are related to this. Shallower waters are warmer during the growing season and are likely to provide better conditions for fast growth. An understanding of the mechanisms behind these patterns is an important consideration in the management and conservation of this fish stock, which might be particularly vulnerable because the commercial landings are to a large extent dominated by female megrim.

Evolution of a unique predatory feeding apparatus: functional anatomy, development and a genetic locus for jaw laterality in Lake Tanganyika scale-eating cichlids

BackgroundWhile bilaterality is a defining characteristic of triploblastic animals, several assemblages have managed to break this symmetry in order to exploit the adaptive peaks garnered through the lateralization of behaviour or morphology. One striking example of an evolved asymmetry in vertebrates comes from a group of scale-eating cichlid fishes from Lake Tanganyika. Members of the Perissodini tribe of cichlid fishes have evolved dental and craniofacial asymmetries in order to more effectively remove scales from the left or right flanks of prey. Here we examine the evolution and development of craniofacial morphology and laterality among Lake Tanganyika scale-eating cichlids.ResultsUsing both geometric and traditional morphometric methods we found that the craniofacial evolution in the Perissodini involved discrete shifts in skeletal anatomy that reflect differences in habitat preference and predation strategies. Further, we show that the evolutionary history of the Perissodini is characterized by an accentuation of craniofacial laterality such that certain taxa show elaborate sided differences in craniofacial shape consistent with the sub-partitioning of function between sides of the head during attacks. Craniofacial laterality in the scale-eating specialist Perissodus microlepis was found to be evident early in development and exhibited a unimodal distribution, which is contrary to the adult condition where jaw laterality has been described as a discrete, bimodal antisymmetry. Finally, using linkage and association analyses we identified a conserved locus for jaw handedness that segregates among East African cichlids.ConclusionsWe suggest that, during the evolution of the Perissodini, selection has accentuated a latent, genetically determined handedness of the craniofacial skeleton, enabling the evolution of jaw asymmetries in order to increase predation success. Continued work on the developmental genetic basis of laterality in the Perissodini will facilitate a better understanding of the evolution of this unique group of fishes, as well as of left-right axis determination among vertebrates in general.

Habitat and morphological differentiation between Pohlia annotina and P. drummondii (Mniaceae) at higher elevations in Yakushima Island, Japan

Habitat segregation between two closely related Pohlia species, P. annotina and P. drummondii, was documented on the basis of field observations at higher elevations in Yakushima Island, supplemented with molecular analysis to confirm the species identities. Both species, belonging to the P. annotina complex, grow on bare soils and have similar gametophytic features as well as heavy dependence on asexual reproduction by propagules produced in leaf axils. The species show a clear difference in habitat preference: P. drummondii is strictly confined to invariably wet or moist soils such as at the edge of bog swamps or streamlets in mountain trails excavated by heavy rains, while P. annotina is mostly found in less humid habitats even if both species sometimes grow side-by-side. A phylogenetic tree using rbcL sequences confirmed that P. annotina, P. drummondii and P. flexuosa, another member of the complex, represent distinct species. In addition to the usual vermicular propagules, Japanese plants of P. annotina and P. flexuosa were shown for the first time to have several other kinds of propagules, as also found in European and American plants. Morphological changes during propagule development in Japanese P. drummondii are also reported.

Differences in Preference and Performance of the Water Lily Leaf Beetle,Galerucella nymphaeaePopulations on Native and Introduced Aquatic Plants

Plant invasions represent ecological opportunities for herbivorous insects able to exploit novel host plants. The availability of new hosts and rapid adaptations may lead to host race formation and ultimately speciation. We studied potential host race formation in the water lily leaf beetle, Galerucella nymphaeae, in response to invasion by water chestnut, Trapa natans, in eastern North America. This leaf beetle is well suited for such studies because previous work showed that different herbivore populations follow different "evolutionary pathways" and specialize locally in response to differences in habitat preferences and host plant availability. We compared host preference and performance of G. nymphaeae offspring originating from T. natans and offspring of individuals originating from an ancestral host Nuphar lutea, yellow water lily, on T. natans and three native hosts (N. lutea, Nympheae odorata, and Brasenia schreberi). Regardless of origin (Trapa or Nuphar), adults strongly preferred their native host, N. lutea, over T. natans. Although laboratory survival rates (larva to pupa) were extremely high (80%) regardless of origin or host offered, survival rates in a common garden were greatly reduced, particularly for T. natans (24%) and to a lesser extent on N. lutea (54%), regardless of beetle origin. Larval drowning during more frequent leaf changes when developing on small Trapa leaves seems to be responsible for this difference. Preference of females for N. lutea is beneficial considering the much higher larval survival on the ancestral host. Abundant T. natans where the plant is invasive provides an alternative food source that beetles can use after egg/larval loads on their preferred host reach carrying capacity, but this utilization comes at a cost of high larval mortality.

Mixtures of GAMs for habitat suitability analysis with overdispersed presence/absence data

A new approach to species distribution modelling based on unsupervised classification via a finite mixture of GAMs incorporating habitat suitability curves is proposed. A tailored EM algorithm is outlined for computing maximum likelihood estimates. Several submodels incorporating various parameter constraints are explored. Simulation studies confirm that under certain constraints, the habitat suitability curves are recovered with good precision. The method is also applied to a set of real data concerning presence/absence of observable small mammal indices collected on the Tibetan plateau. The resulting classification was found to correspond to species level differences in habitat preference described in the previous ecological work.