Field observation,capture and anesthesia of a colugo (Galeopterus variegatus) in Laos

In the course of the wildlife rescue program on the Nakai Plateau during the Nam Theun 2 Hydropower Project a colugo (Galeopterus variegatus) was captured in September 2008. Following the project's general wildlife capture protocol sampling and measuring were conducted during monitored anesthesia. This is the second field observation of a free ranging colugo in Laos and the first documented anesthesia in this species.     

Shifts from native to invasive small mammals across gradients from tropical forest to urban habitat in Borneo

Urbanization has paved the way for the spread of commensal rodents at global scale. However, it is largely unknown how these species use tropical anthropogenic landscapes originally covered with forests and inhabited by diverse small mammal assemblages. We surveyed non-flying small mammals in various urban and suburban habitat types and adjacent forest in the tropical town of Kota Kinabalu in Borneo. We used occupancy and polynomial regression models to determine variation in species occurrences along gradients of land-use intensity. Müller’s sundamys (Sundamys muelleri) was the only native small mammal species found in urban and suburban landscapes with a continuous decrease in occurrence probability from forests to urban habitats. The invasive Asian black rat (Rattus rattus species complex) and the invasive Asian house shrew (Suncus murinus) had the highest occurrence probabilities in habitats of intermediate land-use intensity, but Asian black rats are also likely to occasionally invade forested habitats and occupied urban habitats in sympatry with the Norway rat (Rattus norvegicus). In urban and suburban habitats, fallow land possibly favoured the occurrence of S. muelleri and S. murinus. Other native small mammal species (Muridae, Sciuridae, Tupaiidae) were found only in forested areas. Our study shows that native small mammals found in forest are largely replaced by invasive species in urban and suburban habitats. Due to their occurrence in habitats of various land use intensities, S. muelleri and R. rattus comprise central links between forest wildlife and urban species, an association that is important to consider in studies of parasite and disease transmission dynamics.     

Dendrochronological potential of four neotropical dry-forest tree species: Climate-growth correlations in northeast Brazil

Tropical dry forests (TDF) are highly important tropical forest ecosystems. Yet, these forests are highly threatened, usually neglected and only poorly studied. Understanding the long-term influences of environmental conditions on tree growth in these forests is crucial to understand the functioning, carbon dynamics and potential responses to future climate change of these forests. Dendrochronology can be used as a tool to provide these insights but has only scantly been applied in (dry) tropical forests. Here we evaluate the dendrochronological potential of four Caatinga neotropical dry forest tree species – Aspidosperma pyrifolium, Ziziphus joazeiro, Tabebuia aurea, and Libidibia ferrea – collected in two locations in northeastern Brazil (Sergipe state). We provide an anatomical characterization of the ring boundaries for the four species and investigate correlations of their growth with local and regional climatic variables. All four species form annual rings and show high inter-correlation (up to 0.806) and sensitivity (up to 0.565). Growth of all species correlated with local precipitation as well as with sea-surface temperatures in the tropical Atlantic and/or tropical Pacific oceans. We also show teleconnections between growth and the El Niño South Oscillation. The strong dependence of tree on precipitation is worrisome, considering that climate change scenarios forecast increased drought conditions in the Caatinga dry forest. Including more species and expanding dendrochronological studies to more areas would greatly improve our understanding of tree growth and functioning in TDFs. This type of knowledge is essential to assist the conservation, management and restoration of these critical tropical ecosystems.     

Sloth Hair as a Novel Source of Fungi with Potent Anti-Parasitic,Anti-Cancer and Anti-Bacterial Bioactivity

The extraordinary biological diversity of tropical forests harbors a rich chemical diversity with enormous potential as a source of novel bioactive compounds. Of particular interest are new environments for microbial discovery. Sloths – arboreal mammals commonly found in the lowland forests of Panama – carry a wide variety of micro- and macro-organisms on their coarse outer hair. Here we report for the first time the isolation of diverse and bioactive strains of fungi from sloth hair, and their taxonomic placement. Eighty-four isolates of fungi were obtained in culture from the surface of hair that was collected from living three-toed sloths (Bradypus variegatus, Bradypodidae) in Soberanía National Park, Republic of Panama. Phylogenetic analyses revealed a diverse group of Ascomycota belonging to 28 distinct operational taxonomic units (OTUs), several of which are divergent from previously known taxa. Seventy-four isolates were cultivated in liquid broth and crude extracts were tested for bioactivity in vitro. We found a broad range of activities against strains of the parasites that cause malaria (Plasmodium falciparum) and Chagas disease (Trypanosoma cruzi), and against the human breast cancer cell line MCF-7. Fifty fungal extracts were tested for antibacterial activity in a new antibiotic profile screen called BioMAP; of these, 20 were active against at least one bacterial strain, and one had an unusual pattern of bioactivity against Gram-negative bacteria that suggests a potentially new mode of action. Together our results reveal the importance of exploring novel environments for bioactive fungi, and demonstrate for the first time the taxonomic composition and bioactivity of fungi from sloth hair.     

Distribution Pattern and Climate Preferences of the Representatives of the Cosmopolitan Genus Sirthenea Spinola, 1840 (Heteroptera: Reduviidae: Peiratinae)

The main goal of this study was to predict, through the use of GIS tool as ecological niche modelling, potentially suitable ecological niche and defining the conditions of such niche for the representatives of the cosmopolitan genus Sirthenea. Among all known genera of the subfamily Peiratinae, only Sirthenea occurs on almost all continents and zoogeographical regions. Our research was based on 521 unique occurrence localities and a set of environmental variables covering the whole world. Based on occurrence localities, as well as climatic variables, digital elevation model, terrestrial ecoregions and biomes, information about the ecological preferences is given. Potentially useful ecological niches were modelled using Maxent software, which allowed for the creation of a map of the potential distribution and for determining climatic preferences. An analysis of climatic preferences suggested that the representatives of the genus were linked mainly to the tropical and temperate climates. An analysis of ecoregions also showed that they preferred areas with tree vegetation like tropical and subtropical moist broadleaf forests biomes as well as temperate broadleaf and mixed forest biomes. Therefore, on the basis of the museum data on the species occurrence and ecological niche modelling method, we provided new and valuable information on the potentially suitable habitat and the possible range of distribution of the genus Sirthenea along with its climatic preferences.     

Characterizing growth rings in the trees of Perú: A wood anatomical overview for potential applications in dendroecological-related fields

Sustainable forestry requires accurate ecological information such as species composition, growth rates and recruitment dynamics. Tree growth rates are usually obtained through long-term periodic re-measurements of individual trees or through the analysis of tree growth rings in stem cross sections. However, tree growth ring analysis was traditionally thought to be only possible in biomes with strong seasonality such as those found in high latitude temperate regions. A lack of data on the occurrence and characteristics of tree rings in tropical trees may be due to a lack of investigations. Here we characterise the growth rings of 183 tree species from seven forest types across an altitudinal gradient in northern and central Perú at macro- and microscopic levels. A correspondence analysis showed an association between phylogenetic relatedness and the level of distinctiveness in the growth rings. Deciduous species of seasonally dry tropical forests were associated with distinct growth rings and mainly delimited by marginal parenchyma, while indistinct growth rings were associated with evergreen trees from lowland Amazonian and pre-montane wet forests. Additionally, for the first time the presence of growth ring boundaries defined by marginal phloem is reported in two tropical tree species, Gallesia integrifolia (Spreng.) Harms and Vochysia mapirensis Rusby. This contribution represents the most exhaustive record to date of the occurrence and anatomy of growth rings in trees of the Peruvian tropics, which can be used to inform future dendrochronological studies.     

Why tropical forest lizards are vulnerable to climate warming

Biological impacts of climate warming are predicted to increase with latitude, paralleling increases in warming. However, the magnitude of impacts depends not only on the degree of warming but also on the number of species at risk, their physiological sensitivity to warming and their options for behavioural and physiological compensation. Lizards are useful for evaluating risks of warming because their thermal biology is well studied. We conducted macrophysiological analyses of diurnal lizards from diverse latitudes plus focal species analyses of Puerto Rican Anolis and Sphaerodactyus. Although tropical lowland lizards live in environments that are warm all year, macrophysiological analyses indicate that some tropical lineages (thermoconformers that live in forests) are active at low body temperature and are intolerant of warm temperatures. Focal species analyses show that some tropical forest lizards were already experiencing stressful body temperatures in summer when studied several decades ago. Simulations suggest that warming will not only further depress their physiological performance in summer, but will also enable warm-adapted, open-habitat competitors and predators to invade forests. Forest lizards are key components of tropical ecosystems, but appear vulnerable to the cascading physiological and ecological effects of climate warming, even though rates of tropical warming may be relatively low.     

Galling: the prevalent form of insect folivory in the latest Neogene monsoon-influenced tropical forests of the Chotanagpur Plateau,eastern India

Indian Cenozoic deposits contain well-preserved diverse angiosperm leaf assemblages, but galling, a common form of angiosperm leaf damage in modern tropical forests, has not been well-documented. Here we report insect herbivory on diverse angiosperm fossil leaf specimens from Pliocene (Rajdanda Formation) sediments of the Chotanagpur Plateau, eastern India, revealing that galling was the most common form of folivory in the latest Neogene monsoon-adapted tropical forests of eastern India. Diverse well-preserved galls are described on the basis of their size, shape and position on the host angiosperm leaf remains. Nine gall damage types (DT 32, DT 33, DT 34, DT 80, DT 83, DT 85, DT 110, DT 120, and DT 144) are identified. They are compared with extant galls and the probable gall inducers making morphologically similar galls on related host tropical plant species of Ficus, Mangifera, Albizia, Galactia, Ziziphus, Hylodesmum, Adina, and Psidium. The gall producers belong to the insect orders Orthoptera, Hemiptera, Hymenoptera, Coleoptera, Lepidoptera, and Diptera (Cecidomyiidae). Although the detailed morphology of the phytophagous insects associated with the recovered fossil leaves is unknown, our findings indicate that many modern plant-insect relationships were likely established by the Pliocene. The reconstructed warm, humid Pliocene climate with a weak monsoon seasonality was conducive to extensive galling activity during this time.     

Genetic diversity analysis in disjunct populations of Rhododendron arboreum from the temperate and tropical forests of Indian subcontinent corroborate Satpura hypothesis of species migration

Rhododendron arboreum of the family Ericaceae represents one of the ancient relict tree species of the genus showing extreme disjunction in the Indian subcontinent. It is represented by two sub-species viz., ssp. arboreum Smith in the forests of north-eastern India (temperate) and spp. nilagiricum (Zenker) Tagg distributed in the southern Western Ghats (tropical) of India with apparently no distribution in the intervening plains. 35 Samples corresponding to different locations in the tropical montane forests of Nilgiris and temperate forests of northeast India were analyzed for distribution of genetic variation using 25 random primers. Relatively high genetic diversity was measured in the temperate populations (Ht = 0.21; Nm = 1.13) than tropical Rhododendrons. The hierarchical analysis of molecular variance showed that among the total variance, 25% is residing within populations while 63% of variance is among regions apparently revealing that disjunct distribution has structured genetic differentiation pattern in this species. Grouping of samples was in conformity with their spatial distribution, which was confirmed by UPGMA cluster analysis and PCA scatter plot. The taxon with its unique distribution pattern and wide cross compatibility between sub-species is however threatened by low genetic variation and gene flow that catalyses it’s shifting towards genetic drift and hence long-term conservation strategies need to be formulated particularly for the tropical Rhododendron sub-species. Among the various hypotheses and theory proposed to explain the Malayan affinity in the flora and fauna of Western Ghats, Satpura hypothesis based on dispersal model of distribution largely explains the discontinues distribution of R. arboreum.     

Comparison of pasture types in the tropical Andes: Species composition,distribution, nutritive value and responses to environmental change

Pastoralism is the main land use in the humid tropical Andes of South America. Wide areas of mountain rainforest have been cleared for gaining pastureland. Due to the lack of indigenous useful grasses in the pristine forests, mainly exotic grass species have been used for establishing the pastures. In the Ecuadorian Andes, Axonopus compressus, Melinis minutiflora, Pennisetum clandestinum and Holcus lanatus are common pasture grass species. Their preference for certain microsites resulted in a mosaic of different pasture types, which reflect the differing ecological conditions on the undulating terrain of the mountain slopes. During the last decades, however, another exotic grass species, Setaria sphacelata has widely been introduced which, because of its fast growth on some of the sites could successfully suppress the formerly dominant plant species. With respect to the changing microclimate and cattle stocking rates the present study explored, whether planting Setaria is the best option for the common low-input type of pasture farming in these tropical mountains. In a study over twenty years, the development of four main pasture types, dominated by the above-mentioned grass species was investigated in areas with and without Setaria, and their topographical occurrence on the sloping terrain was analyzed. On forty-eight plots a pairwise (with or without Setaria) comparison of species composition and diversity, biomass production, forage quality and soil properties was performed. Although Setaria grows faster than the other grass species, its productivity was only higher on flat terrain. The nutritive value of the Setaria plots was at best equivalent to that of the former pastures, while species richness was consistently lower. Our results suggest the maintenance of a terrain-adapted diversification of the pastures and in particular the use of Setaria only on flat terrain.     

Notes on Collybia V. Gymnopus section Levipedes in tropical South America,with comments on Collybia

Five species of Gymnopus section Levipedes are reported for tropical South America. Two of these, Gymnopus macropus and G. nubicola, are newly described. Collybia laccata is considered synonymous with G. mucubajiensis comb. nov. now known from Andean Ecuador; both were originally described from the Venezuelan páramo. Gymnopus alkalivirens and G. semihirtipes are compared to G. mucubajiensis. Gymnopus spongiosus, previously known from the eastern United States, is newly reported from Colombian Quercus forests and is proposed as a new combination. Gymnopus dryophilus is, at present, not known from tropical South America, but extralimital material from nearby Costa Rica is described for comparison. No known species of Collybia s.str. have been identified from tropical South America.     

Interactions between terrestrial mammals and the fruits of two neotropical rainforest tree species

Mammalian frugivory is a distinctive biotic interaction of tropical forests; however, most efforts in the Neotropics have focused on cases of animals foraging in the forest canopy, in particular primates and bats. In contrast much less is known about this interaction when it involves fruits deposited on the forest floor and terrestrial mammals. We conducted a camera-trapping survey to analyze the characteristics of the mammalian ensembles visiting fruits of Licania platypus and Pouteria sapota deposited on the forest floor in a well preserved tropical rainforest of Mexico. Both tree species produce large fruits but contrast in their population densities and fruit chemical composition. In particular, we expected that more species of terrestrial mammals would consume P. sapota fruits due to its higher pulp:seed ratio, lower availability and greater carbohydrate content. We monitored fruits at the base of 13 trees (P. sapota, n = 4 and L. platypus, n = 9) using camera-traps. We recorded 13 mammal species from which we had evidence of 8 consuming or removing fruits. These eight species accounted for 70% of the species of mammalian frugivores active in the forest floor of our study area. The ensemble of frugivores associated with L. platypus (6 spp.) was a subset of that associated with P. sapota (8 spp). Large body-sized species such as Tapirus bairdii, Pecari tajacu and Cuniculus paca were the mammals more frequently interacting with fruits of the focal species. Our results further our understanding of the characteristics of the interaction between terrestrial mammalian frugivores and large-sized fruits, helping to gain a more balanced view of its importance across different tropical forests and providing a baseline to compare against defaunated forests.     

Differences in climate-growth relationships between two tree species that co-occur in a seasonally dry tropical forest in Northeastern Brazil

Seasonally dry tropical forests are an important global climate regulator and represent one of main drivers of carbon sink dynamics. However, projections of climate change suggest future productivity losses and negative impacts on forest functioning. Understanding the interaction between climate variability and tree growth responses between species with different growth strategies represents a crucial challenge to forecast ecosystem functioning in the future. Here we used tree ring chronology to evaluate changes in growth and climate sensitivity of two tropical tree species that co-occur in a seasonally dry tropical forest in Brazil: Cedrela odorata and Ceiba glaziovii. Using Pearson correlations and linear regressions we explored how growth variability is correlated with local (precipitation, temperature) and global (ocean temperature and El Niño Southern Oscillation - ENSO) climatic factors. Tree growth was closely related with precipitation in C. odorata (r = 0.59) and C. glaziovii (0.24). Differences were found at monthly level, which C. odorata showing greater sensitivity in the beginning of rainy season. The South Atlantic Temperature was positively correlated with C. odorata, while ENSO was negatively correlated. Our results showed a dominant effect of precipitation on tree growth and suggest that are different growth strategies among species, which C. odorata being the most sensitive to drought and C. glaziovii more adapted with parenchyma in trunk. Therefore, C. odorata is probably more vulnerable to the deleterious effects of future climate change than C. glaziovii. Our findings highlight the importance of understanding the climate sensitivity of different seasonally dry tropical forest species, which is critical to predicting carbon dynamics in tropical regions. These also reveal that differences in sensitivity must be considered when prioritizing conservation measures for seasonally dry tropical forests.     

Multi‐scale effects of habitat structure and landscape context on a vertebrate with limited dispersal ability (the brown‐throated sloth,Bradypus variegatus)

As human population, food consumption, and demand for forest products continue to rise over the next century, the pressures of land‐use change on biodiversity are projected to intensify. In tropical regions, countryside habitats that retain abundant tree cover and structurally complex canopies may complement protected areas by providing suitable habitats and landscape connectivity for a significant portion of the native biota. Species with low dispersal capabilities are among the most at risk of extinction as a consequence of land‐use change. We assessed how the spatial distribution of the brown‐throated sloth (Bradypus variegatus), a model species for a vertebrate with limited dispersal ability, is shaped by differences in habitat structure and landscape patterns of countryside habitats in north‐central Costa Rica using a multi‐scale framework. We quantified the influence of local habitat characteristics and landscape context on sloth occurrence using mixed‐effects logistic regression models. We recorded 27 sloths within countryside habitats and found that both local and landscape factors significantly influenced their spatial distribution. Locally, sloths favored structurally complex habitats, with greater canopy cover and variation in tree height and basal area. At the landscape scale, sloths demonstrated a preference for habitats with high proportions of forest and nearby large tracts of forest. Although mixed‐use areas and tree plantations are not substitutes for protected forests, our results suggest they provide important supplemental habitats for sloths. To promote the conservation and long‐term viability of sloth populations in the tropical countryside, we recommend that land managers retain structurally complex vegetation and large patches of native habitat.     

Influence of piperonyl butoxide on the toxicity of organophosphate insecticides to three species of freshwater benthic invertebrates

Toxicity tests were conducted with amphipods (Hyalella azteca), chironomids (Chironomus tentans) and oligochaetes (Lumbriculus variegatus) exposed to a series of organophosphate insecticides in the absence or presence of piperonyl butoxide (PBO), an inhibitor of cytochrome(s) P450. Piperonyl butoxide effectively reduced the toxicity to H. azteca and C. tentans of three organophosphates (diazinon, chlorpyrifos, azinphos-methyl) which undergo metabolic activation by cytochrome(s) P450. Coadministration of PBO with another organophosphate (dichlorvos) which is not activated by cytochrome(s) P450, did not reduce the toxicity to the two species. Lumbriculus variegatus was relatively insensitive to the organophosphates, and PBO did not reduce their toxicity to the oligochaete. These data indicate that both H. azteca and C. tentans possess cytochrome P450-mediated MOs capable of metabolizing organic xenobiotics. However, the degree to which L. variegatus might be capable of the oxidative metabolism of organic xenobiotics is uncertain.     

Distinctive Bacterial Communities in the Rhizoplane of Four Tropical Tree Species

It is known that the microbial community of the rhizosphere is not only influenced by factors such as root exudates, phenology, and nutrient uptake but also by the plant species. However, studies of bacterial communities associated with tropical rainforest tree root surfaces, or rhizoplane, are lacking. Here, we analyzed the bacterial community of root surfaces of four species of native trees, Agathis borneensis, Dipterocarpus kerrii, Dyera costulata, and Gnetum gnemon, and nearby bulk soils, in a rainforest arboretum in Malaysia, using 454 pyrosequencing of the 16S rRNA gene. The rhizoplane bacterial communities for each of the four tree species sampled clustered separately from one another on an ordination, suggesting that these assemblages are linked to chemical and biological characteristics of the host or possibly to the mycorrhizal fungi present. Bacterial communities of the rhizoplane had various similarities to surrounding bulk soils. Acidobacteria, Alphaproteobacteria, and Betaproteobacteria were dominant in rhizoplane communities and in bulk soils from the same depth (0–10?cm). In contrast, the relative abundance of certain bacterial lineages on the rhizoplane was different from that in bulk soils: Bacteroidetes and Betaproteobacteria, which are known as copiotrophs, were much more abundant in the rhizoplane in comparison to bulk soil. At the genus level, Burkholderia, Acidobacterium, Dyella, and Edaphobacter were more abundant in the rhizoplane. Burkholderia, which are known as both pathogens and mutualists of plants, were especially abundant on the rhizoplane of all tree species sampled. The Burkholderia species present included known mutualists of tropical crops and also known N fixers. The host-specific character of tropical tree rhizoplane bacterial communities may have implications for understanding nutrient cycling, recruitment, and structuring of tree species diversity in tropical forests. Such understanding may prove to be useful in both tropical forestry and conservation.     

Why be cryptic? Choice of host urchin is not based on camouflage in the caridean shrimp Gnathophylloides mineri

The caridean shrimp Gnathophylloides mineri lives among the spines of various species of sea urchins. The shrimp has cryptic coloration that closely matches the coloration of the Caribbean urchin Tripneustes ventricosus. Despite this camouflage, in Jamaica, G. mineri is three times more abundant on the urchin Lytechinus variegatus than on T. ventricosus. L. variegatus exhibits more pronounced covering behavior than T. ventricosus. In laboratory choice experiments, the shrimp exhibited no preference between live, uncovered T. ventricosus or L. variegatus. Similarly, there was no preference between models (the tests, with spines attached, of hollowed out urchins) of T. ventricosus or L. variegatus without cover, or between models of T. ventricosus or L. variegatus with switched cover (i.e., each model was covered with the debris that had belonged to its partner when collected). There was, however, a significant preference for L. variegatus models with their natural covering over T. ventricosus with their natural covering. The shrimp may prefer L. variegatus with its extensive covering over T. ventricosus with extensive covering because the spines of the former are typically erect, as opposed to the spines of T. ventricosus, which usually lay flat across the test and would not give the shrimp much room to maneuver under the debris layer. Our study indicates that despite effective morphological and behavioral traits that render an organism highly cryptic, other, more effective, means of concealment may undermine the usefulness of this crypsis.     

Potential for Nematode Control by Mycofloras Endemic in the Tropics

Results of mycological surveys of root-knot and cyst nematodes from tropical regions indicate that most fungal species associated with females or cysts of species of Globodera, Heterodera, and Meloidogyne are those found with nematodes from temperate areas. Some fungal species, however, were found in higher frequency in tropical regions than in temperate countries; e.g., Cylindrocarpon destructans and Ulocladium atrum were the most common species associated with G. pallida and G. rostochiensis cysts in Peru. These fungi are not so frequent in nematodes from temperate areas. Fungi associated with diseased nematodes in the tropics vary greatly in nutritional requirements and include thermophilic species as well as cold-tolerant fungi. Multi-cropping systems possible in most tropical regions may be designed to increase the frequency of occurrence of microbial species antagonistic to phytonematodes.     

Landscape Genetics of Leaf-Toed Geckos in the Tropical Dry Forest of Northern Mexico

Habitat fragmentation due to both natural and anthropogenic forces continues to threaten the evolution and maintenance of biological diversity. This is of particular concern in tropical regions that are experiencing elevated rates of habitat loss. Although less well-studied than tropical rain forests, tropical dry forests (TDF) contain an enormous diversity of species and continue to be threatened by anthropogenic activities including grazing and agriculture. However, little is known about the processes that shape genetic connectivity in species inhabiting TDF ecosystems. We adopt a landscape genetic approach to understanding functional connectivity for leaf-toed geckos (Phyllodactylus tuberculosus) at multiple sites near the northernmost limit of this ecosystem at Alamos, Sonora, Mexico. Traditional analyses of population genetics are combined with multivariate GIS-based landscape analyses to test hypotheses on the potential drivers of spatial genetic variation. Moderate levels of within-population diversity and substantial levels of population differentiation are revealed by F _ST and D _est. Analyses using structure suggest the occurrence of from 2 to 9 genetic clusters depending on the model used. Landscape genetic analysis suggests that forest cover, stream connectivity, undisturbed habitat, slope, and minimum temperature of the coldest period explain more genetic variation than do simple Euclidean distances. Additional landscape genetic studies throughout TDF habitat are required to understand species-specific responses to landscape and climate change and to identify common drivers. We urge researchers interested in using multivariate distance methods to test for, and report, significant correlations among predictor matrices that can impact results, particularly when adopting least-cost path approaches. Further investigation into the use of information theoretic approaches for model selection is also warranted.