Zootaxa 3722 (1): 001–021 (21 Oct. 2013)
Two new stingrays (Chondrichthyes: Dasyatidae) from the eastern Indonesian Archipelago
PETER R. LAST & WILLIAM T. WHITE
Two new stingrays, Dasyatis longicauda sp. nov. and Himantura javaensis sp. nov., are described from material collected in the eastern Indonesian Archipelago. These species, which are both relatively small stingrays (both probably smaller than 40 cm DW), have been confused with closest relatives in the region. Dasyatis longicauda sp. nov., known from West Papua, differs from its congener, the Australian endemic D. fluviorum, in having a slightly lower vertebral count, lower pectoral-radial count, a longer tail, larger and less numerous thorns along the mid-disc and tail, as well as a different CO1
Barcode. Himantura javaensis sp. nov., known only from southern Java (near Cilacap), belongs to a complex of small whiprays which also includes another Indonesian species, H. walga. Apart from major differences in squamation and a different CO1 Barcode, Himantura javaensis is more brownish in coloration, has more vertebrae, a longer tail, smaller eye and orbit, more posteriorly positioned sting, shorter adult claspers, shorter pelvic fin, and differs in various measurements around the head.
Zootaxa 3722 (1): 061–072 (21 Oct. 2013)
A new frog species (Microhylidae: Cophixalus) from boulder-pile habitat of Cape Melville, north-east Australia
CONRAD J. HOSKIN
In Australia, microhylid frogs are found almost exclusively in the tropical north-east, but in this region diversity is high. Sixteen species occur in the Wet Tropics region and a further six species are found further north on Cape York Peninsula. Most Australian microhylid species belong to the genus Cophixalus (18 species). The majority of these have highly localized distributions, with two-thirds being found on single mountain ranges. While most Cophixalus are small (10–29 mm snout to vent length) rainforest species, four differ dramatically in morphology and ecology, being large (30–53 mm) species
that inhabit isolated areas of jumbled boulder-pile habitat. Here I describe a new species of Cophixalus from boulderpile habitat in the Melville Range on Cape Melville, north-east Cape York Peninsula. Cophixalus petrophilus sp. nov. is highly distinct from all congeners in morphology, colour pattern and mating call. This species is restricted to deeply piled granite boulder habitat that is largely devoid of vegetation. As for the other four boulder-pile Cophixalus, C. petrophilus sp. nov. is large and shows other similar morphological adaptations to this unique habitat (e.g., long limbs, large finger
discs). However, it is notable in that it is the smallest of the boulder-pile species (26–32 mm) and it has particularly large eyes. I speculate that the latter trait is an adaptation to dimly lit conditions deep within the boulder-field. Cophixalus petrophilus sp. nov. was only found in exposed boulder habitat, whereas the co-occurring boulder species, C. zweifeli, was found using forested areas on and adjacent to the boulder-fields at night. Cape Melville is the only boulder-field with two co-occurring boulder Cophixalus and it appears that there is habitat partitioning between them. Cophixalus petrophilus sp. nov. has a highly localised distribution but appears common within this and is probably secure.
Zootaxa 3722 (1): 083–091 (21 Oct. 2013)
Anampses viridis Valenciennes 1840 (Pisces: Labridae)—a case of taxonomic confusion and mistaken extinction
BARRY C. RUSSELL & MATTHEW T. CRAIGAnampses viridis Valenciennes 1840 is known from only three specimens collected from Mauritius, and despite intensive sampling, the species has not been seen or reported since it was originally described. This apparent failure to ‘rediscover’ A. viridis at Mauritius has led to speculation that it is extinct, and the species has been widely cited as an example of a marine fish extinction. Far from being extinct, Anampses viridis has been taxonomically confused and actually is the adult male (terminal phase) colour form and a junior synonym of A. caeruleopunctatus Rüppell 1829, a species that is common and widespread throughout the Indo-West Pacific region.
Characterizing the mammalian hair present in Great Tit (Parus major) nests
Kateřina Ondrušová, Peter Adamík
Bird Study Vol. 60, Iss. 3, 2013
Many birds are known to incorporate mammal hair into their nest lining, but the frequency with which they use hair from different mammals is unknown. We performed one of the first detailed examinations of mammalian hair from 54 Great Tit nests. We identified 5317 hairs belonging to 21 mammal species. Almost all of the examined nests contained hair from Roe Deer (Capreolus capreolus), but hair from Wild Boars (Sus scrofa), European Hares (Lepus europaeus) and Red Foxes (Vulpes vulpes) was also common.
Non-linear phenomena in little spotted kiwi calls
Andrew Digby, Ben D. Bell, Paul D. Teal
Non-linear phenomena (NLP) in vocalizations may have adaptive functions, such as increasing acoustic impact or conveying fitness or identity information. Yet despite their potential to impart behavioural information, these spectral features have not been studied in most bird species and many genera. This applies to the New Zealand kiwi (Apterygidae), with NLP-like features indicated in one species, but not explored further. Yet as nocturnal and cryptic birds heavily reliant on vocal communication, kiwi are ideal species in which to assess the function of these structures. Furthermore, kiwi are acoustically typical but taxonomically and ecologically unique among birds, so can provide an important reference for determining the behavioural relevance of NLP in other bird species. We have assessed the occurrence of NLP in little spotted kiwi (Apteryx owenii) calls, in the first detailed study of such features in a ratite. NLP in the form of subharmonics are common in this species. We tested for possible adaptive functions of these features by comparing their occurrence with call spectral parameters and conditions. Subharmonics increased with frequency and during calls produced in territorial contexts, indicating that these features may provide acoustic impact, possibly to convey aggression or fitness information. Our results also suggest that NLP are unlikely to provide identification information in this kiwi species.
Nasal and oral calls in mother and young trunk-nosed saiga antelopes, Saiga tatarica
Ilya A. Volodin, Olga V. Sibiryakova, Lyudmila E. Kokshunova, Roland Frey, Elena V. Volodina
The trunk-like nose of the saiga antelope Saiga tatarica is a striking example of an exaggerated trait, assumed to having evolved as a dust filter for inhaled air. In addition, it functions to elongate the vocal tract in harem saiga males for producing low-formant calls that serve as a cue to body size for conspecifics. This study applies the source–filter theory to the acoustics of nasal, oral and nasal-and-oral calls that were recorded from a captive herd of 24 mother and 32 neonate saigas within the first 10 days postpartum. Anatomical measurements of the nasal and oral vocal tracts of two specimens (one per age class) helped to establish the settings for the analysis of formants. In both mother and young, the lower formants of nasal calls/call parts were in agreement with the source–filter theory, which suggests lower formants for the longer nasal vocal tract than for the shorter oral vocal tract. Similar fundamental frequencies of the nasal and oral parts of nasal-and-oral calls were also in agreement with the source–filter theory, which postulates the independence of source and filter. However, the fundamental frequency was higher in oral than in nasal calls, probably due to the higher emotional arousal during the production of oral calls. We discuss production mechanisms and the ontogeny of formant patterns of oral and nasal calls among bovid and cervid species with and without a trunk-like nose.
Improving individual identification in captive Eastern grey wolves (Canis lupus lycaon) using the time course of howl amplitudes
Holly Root-Gutteridge, Martin Bencsik, Manfred Chebli, Louise K. Gentle, Christopher Terrell-Nield, Alexandra Bourit, Richard W. Yarnell
Many bioacoustic studies have been able to identify individual mammals from variations in the fundamental frequency (F 0) of their vocalizations. Other characteristics of vocalization which encode individuality, such as amplitude, are less frequently used because of problems with background noise and recording fidelity over distance. In this paper, we investigate whether the inclusion of amplitude variables improves the accuracy of individual howl identification in captive Eastern grey wolves (Canis lupus lycaon). We also explore whether the use of a bespoke code to extract the howl features, combined with histogram-derived principal component analysis (PCA) values, can improve current individual wolf howl identification accuracies. From a total of 89 solo howls from six captive individuals, where distances between wolf and observer were short, we achieved 95.5% (+9.0% improvement) individual identification accuracy of captive wolves using discriminant function analysis (DFA) to classify simple scalar variables of F 0 and normalized amplitudes. Moreover, this accuracy was increased by 100% when using histogram-derived PCA values of F 0 and amplitudes of the first harmonic. We suggest that individual identification accuracy can be improved by including amplitude changes for species where F 0 has only been included so far. Using DFA on PCA values of both F 0 and amplitude could optimize vocal identification in a range of mammal bioacoustic studies.
Temporal and spectral characteristics of the male Eleutherodactylus coqui two-note vocalization in Hawaii
Francis L. Benevides, William J. Mautz
Temporal and spectral characteristics of the two-note vocalization of the male Eleutherodactylus coqui in Hawaii were investigated and measured in order to establish an average source level of the male coqui. We compared various vocalization parameters obtained from previous research in Puerto Rico with similar parameters measured in Hawaii, including note duration, inter-note interval, call repetition period, centre frequency and bandwidth. Digitized sound records of coqui vocalization were used to calculate the root-mean-square of source level for the frog referenced to a 1 m distance for the Co and Qui notes individually and combined. Additional parameters calculated for the vocalizations were difference in the source levels between Co and Qui notes, duty cycle, ratio of Qui to Co note duration and ratio of the Qui to Co centre frequencies. Most of the frog vocalization parameters were sensitive to air temperature displaying significant regressions over a 4°C temperature range (18.6–22.6°C). Surprisingly, the average ratio of Qui to Co centre frequency among n = 55 frogs was 1.81 with a strikingly low standard deviation of 0.07. The coupling of individual variation in Co and Qui centre frequencies producing such low ratio standard deviation is likely due to body mass-related scaling of laryngeal cartilages, vocal chords and muscles responsible for the vocal emission. Co and Qui centre frequency variations can reveal information about the body size of the calling frogs.
The vocal repertoire of infant giant pandas (Ailuropoda melanoleuca)
Anton Baotic, Angela S. Stoeger, Desheng Li, Chunxiang Tang, Benjamin D. Charlton
Infant giant pandas (Ailuropoda melanoleuca) are highly vocal during the first few weeks of their life. Despite this, no previous studies have attempted to systematically categorize infant giant panda vocalizations into different call types. In this study, we used acoustic and video analyses to split infant giant panda vocalizations into three distinct call types based on their acoustic structure as well as their use in different behavioural contexts. A discriminant functions analysis on the acoustic variables confirmed our initial subjective classification of 281 vocalizations into three call types: the harsh sounding “squawk”, the high-pitched “squall” and the pulsed “croak”. Based on the observed spectral acoustic characteristics, none of these three infant call types appears to be a precursor of an adult giant panda vocalization. In addition, individual call types could not be assigned to specific recording contexts. These findings suggest that infant giant panda vocalizations convey information about a cub’s distress and need, rather than being tied to specific contexts of emission. Our objective demonstration that infant giant pandas have three basic call types provides a foundation for future studies of vocal ontogeny in this highly endangered species.
Zootaxa 3722 (2): 143–169 (22 Oct. 2013)
Three new species of horned frogs, Megophrys (Amphibia: Megophryidae), from northeast India, with a resolution to the identity of Megophrys boettgeri populations reported from the region
STEPHEN MAHONY, EMMA C. TEELING & S.D. BIJU
Northeast India is a well-established region of biological importance but remains poorly understood with regards to the species level identifications of many of its extant amphibians. In this study we examined small sized frogs from the genus Megophrys recently collected from remote and suburban forests in the northeast Indian states of Meghalaya and Arunachal Pradesh, from which we have identified three new species. Megophrys vegrandis sp. nov., Megophrys ancrae sp. nov. and Megophrys oropedion sp. nov. are compared with all known congeners from India and surrounding regions from which they differ based primarily on a combination of morphological characters. Megophrys boettgeri is removed, and Megophrys minor added to the Indian amphibian checklist, through critical review of all literature pertaining to the former species,
and the discovery of an overlooked historical report of the latter species. Two of the new species, Megophrys ancrae sp. nov. and Megophrys vegrandis sp. nov. are known from low and mid elevations within two large protected forests in Arunachal Pradesh, both with poorly studied amphibian fauna. Contrastingly, Megophrys oropedion sp. nov. is currently
known only from small forested areas on the upper reaches of the Shillong Plateau. The importance of the Shillong Plateau as an area of known high amphibian endemicity is highlighted in the light of the miniscule proportion of its land area afforded government protection, raising concerns about the future conservation of its still poorly known species.
Zootaxa 3722 (3): 301–316 (23 Oct. 2013)
A review of the Cnemidophorus lemniscatus group in Central America (Squamata: Teiidae), with comments on other species in the group
JAMES R. MCCRANIE & S. BLAIR HEDGES
We provide the results of a morphological and molecular study on the Honduran Bay Island and mainland populations of the Cnemidophorus lemniscatus complex for which we resurrect C. ruatanus comb. nov. as a full species. Morphological comparison of the Honduran populations to Cnemidophorus populations from Panama led to the conclusion that the Panamanian population represents an undescribed species named herein. In light of these new results, and considering past morphological studies of several South American populations of the C. lemniscatus group, we suggest that three other nominal forms of the group are best treated as valid species: C. espeuti (described as a full species, but subsequently treated as a synonym of C. lemniscatus or a subspecies of C. lemniscatus until this publication), C. gaigei comb. nov., and C. splendidus comb. nov.
Zootaxa 3722 (3): 333–346 (23 Oct. 2013)
A new species of Acanthodactylus Fitzinger 1834 (Sauria: Lacertidae) from southern Iran
NASTARAN HEIDARI, NASRULLAH RASTEGAR POUYANI, ESKANDAR RASTEGAR-POUYANI & MEHDI RAJABIZADEH
A new and distinctive species of lacertid genus Acanthodactylus Fitzinger, 1834 is described from 7 km east of Khamir Port, Hormozgan Province, southern Iran at an elevation of 30–40m above sea level (asl). Analyses of morphological characters
and the comparison with other formerly known species of this genus have proven the status of this taxon as a new, distinct species. Combinations of scalation characters and distinct morphology, coloration and habitat peculiarities in calcareous mountains distinguish Acanthodactylus khamirensis sp.nov from all remaining species of the genus in the area. In order to show the validity of the new species, we carried out a comparative statistical analysis using 13 metric and six meristic morphological characters on all of the neighboring congeners of the new species using descriptive (one-way ANOVA) as well as multivariate analyses (PCA and DFA). The results confirm the specific status of the new taxon. Detailed information and an updated identification key for the genus Acanthodactylus in Iran are presented.
Zootaxa 3722 (3): 361–371 (23 Oct. 2013)
The types of Osteoglossum formosum Müller & Schlegel, 1840 (Teleostei, Osteoglossidae)
MARTIEN J.P. VAN OIJEN & SANCIA E.T. VAN DER MEIJ
The designation of a neotype for Scleropages formosus (Müller & Schlegel, 1840) by Pouyaud et al. (2003) triggered a search for the type specimens of the species, which were found in the collections of the Naturalis Biodiversity Center, Leiden (RMNH) and the Natural History Museum, London (BM(NH)). The publication date of the species is corrected. Moreover, detailed data on the day of capture and the type locality were uncovered. An English translation of the major part of the original Dutch description is provided, and a number of neglected colour descriptions and figures of S. formosus are discussed. Lastly, a lectotype is designated.
Zootaxa 3722 (3): 385–395 (23 Oct. 2013)
A new skink (Scincidae: Saproscincus) from rocky rainforest habitat on Cape Melville, north-east Australia
CONRAD J. HOSKIN
Saproscincus skinks are restricted to wet forest habitats of eastern Australia. Eleven species have previously been described, with most having small distributions in disjunct areas of subtropical and tropical rainforest. The localized distributions and specific habitat requirements of Saproscincus have made them a key group for understanding the biogeographic history of Australia’s rainforests. Here I describe a new species of Saproscincus from the Melville Range on Cape Melville, north-east Australia. The Melville Range is composed of boulder-fields and areas of rainforest in the uplands, and is highly isolated from other areas of elevated rainforest. All individuals of the new species were found on a moist ridgeline, active on boulders under a rainforest canopy or on boulder-field immediately adjacent to rainforest. Saproscincus saltus sp. nov. is highly distinct in morphology and colour pattern. Of particular interest are its long limbs and
digits compared to congeners, which in conjunction with the observed ecology, suggest a long history of association with rock. The discovery of S. saltus sp. nov. extends the distribution of the genus over 100 km north from the nearest congeners in the Wet Tropics region. This species brings the number of vertebrates known to be endemic to the Melville Range to six, which is remarkable for such a small area.
Franziska Freese, Andreas Bernhard, Eve Müller-Deck, Klaus Eulenberger, Handaufzucht eines männlichen Ursons Erethizon dorsatum (Linné, 1758), Der Zoologische Garten, Available online 22 October 2013, ISSN 0044-5169, http://dx.doi.org/10.1016/j.zoolgart.2013.09.001.
One immediately after its birth orphaned American porcupine (Erethizon dorsatum) had to be hand raised. The diet used composed of 12% fatty milk and boiled carrots as well as sun flower oil and minerals. The daily increase of body mass averaged out has been 6g within the first five weeks. During the first four weeks the porcupine suffered intermittently on severe health problems, mainly on pyaemia and ataxias, which could treated successfully. At first the animal was very sociable, later it tried sometimes to bite the keepers.
Michael L. Platt
Personality Traits in Rhesus Macaques (Macaca mulatta) Are Heritable but Do Not Predict Reproductive Output
Lauren J. N. Brent, Stuart Semple, Ann MacLarnon, Angelina Ruiz-Lambides, Janis Gonzalez-Martinez, International Journal of Primatology October 2013
There is growing evidence that behavioral tendencies, or “personalities,” in animals are an important aspect of their biology, yet their evolutionary basis is poorly understood. Specifically, how individual variation in personality arises and is subsequently maintained by selection remains unclear. To address this gap, studies of personality require explicit incorporation of genetic information. Here, we explored the genetic basis of personality in rhesus macaques by determining the heritability of personality components and by examining the fitness consequences of those components. We collected observational data for 108 adult females living in three social groups in a free-ranging population via focal animal sampling. We applied principal component analysis to nine spontaneously occurring behaviors and identified six putative personality components, which we named Meek, Bold, Aggressive, Passive, Loner, and Nervous. All components were repeatable and heritable, with heritability estimates ranging from 0.14 to 0.35. We found no evidence of an association with reproductive output, measured either by infant survival or by interbirth interval, for any of the personality components. This finding suggests either that personality does not have fitness-related consequences in this population or that selection has acted to reduce fitness-associated variation in personality.
Emma Sheehy, Denise B. O’Meara, Catherine O’Reilly, Anthony Smart, Colin Lawton
A non-invasive approach to determining pine marten abundance and predation
European Journal of Wildlife Research October 2013
A non-invasive approach was used to investigate variation in pine marten (Martes martes) abundance between the midlands and east of Ireland, and to determine the frequency of occurrence of squirrels and other small mammals in the diet. Remotely plucked hair samples were genotyped to differentiate between individual animals, and real-time polymerase chain reaction (PCR) was used to identify predator and prey DNA in scats. Macro analysis of prey remains was carried out on a sub sample of scats and the results from both methods are compared. Non-invasive techniques were successful in determining the presence and relative abundance of the pine marten at woodland level. As expected, abundance was found to be higher in the core population of the midlands than in the east. Pine martens were found to reach higher numbers per km2 of forested habitat in Ireland than their British or European counterparts. Both traditional hard part analysis and molecular dietary analysis of mammalian prey yielded similar results. We provide the first evidence of the European pine marten predating upon the North American grey squirrel (Sciurus carolinensis) in its invasive range. While the grey squirrel was not available as a prey item in any of the midlands sites, it was available in the east, where it featured significantly more frequently in the diet than the native red squirrel. In both the midlands and the east the woodmouse is the most frequently occurring mammal in the diet.
Ana Galov, Magda Sindičić, Tibor Andreanszky, Snježana Čurković, Danko Dežđek, Alen Slavica, Günther B. Hartl, Bastian Krueger, High genetic diversity and low population structure in red foxes (Vulpes vulpes) from Croatia, Mammalian Biology – Zeitschrift für Säugetierkunde, Available online 24 October 2013, ISSN 1616-5047, http://dx.doi.org/10.1016/j.mambio.2013.10.003.
Hiroki Koda, Chisako Oyakawa, Akemi Kato, Daisuke Shimizu, Rizaldi, Yasuhiro Koyama, Satoshi Hasegawa
Immature male gibbons produce female-specific songs
Primates October 2013
Gibbons are apes that are well known to produce characteristic species-specific loud calls, referred to as “songs.” Of particular interest is the sex specificity of the “great calls” heard in gibbon songs. However, little is known about the development of such calls. While great calls are given by female gibbons of various ages, they have never been recorded from males. Here, we report two observations of immature male gibbons from two different species, wild Hylobates agilis and captive H. lar, which spontaneously sang female-specific great calls. Based on the video clips, we conclude that immature males also have the potential to produce great calls. Our observations led us to propose a new hypothesis for the development of sexual differentiation in the songs of gibbons, and its implications for the general issue of sex-specific behavior in primates.
DelGiudice, G. D., Sampson, B. A. and Giudice, J. H. (2013), A long-term assessment of the effect of winter severity on the food habits of white-tailed deer. The Journal of Wildlife Management, 77: 1664–1675. doi: 10.1002/jwmg.616
Nutrition is a critical link between environmental and population variation in northern populations of free-ranging white-tailed deer (Odocoileus virginianus). Yet, few studies have investigated winter food habits of northern free-ranging deer and all of these were short-term studies (1–2 winters). Consequently, little information is available on the effect of inter-annual variation in winter severity on browse availability and diet composition of free-ranging deer. We describe winter browse use by white-tailed deer on 4 study sites in northern Minnesota during 1991–2005. We also tested several a priori predictions about how browse use and availability would change as a function of winter severity. We collected browse data from 1,028 feeding trails and recorded 38 available browse species or species groups. The 4 most common browse species (beaked hazel [Corylus cornuta], mountain maple [Acer spicatum], trembling aspen [Populus tremuloides], and speckled alder [Alnus incana]) accounted for 76% of total available stems, and beaked hazel and mountain maple accounted for 68% of total used stems. As expected, browse use and availability distributions were very similar (i.e., deer used many of the available browse resources). Mean number of browse species used did not increase (decreased selection) with snow depth. However, mean browse rate (functional response) increased with increasing snow depth, and use of speckled alder (starvation food) increased when snow depth exceeded 40 cm. In addition, the number of browse species along feeding trails declined and stem abundance increased, on average, with increasing snow depth. Deep snow and increased use of dense conifer cover in northern Minnesota may restrict deer to greater use of lower quality feeding sites. In landscapes where this may occur, habitat management should attempt to minimize over-browsing on feeding sites in proximity to dense conifer cover by maximizing browse abundance and availability, particularly for beaked hazel and mountain maple. Managers also should consider enhancing alternative early-winter feeding sites.
Olson, Z. H., Whittaker, D. G. and Rhodes, O. E. (2013), Translocation history and genetic diversity in reintroduced bighorn sheep. The Journal of Wildlife Management, 77: 1553–1563. doi: 10.1002/jwmg.624
Because genetic diversity provides the substance for adaptation and evolution and its decline signifies the potential for deleterious effects on demography, biologists must understand how management action can facilitate or hinder the retention of genetic diversity at the level of the population being managed. We assessed genetic diversity in 8 reintroduced populations of bighorn sheep using 16 microsatellite markers and a 515-base-pair segment of the mitochondrial control region. Populations were categorized by their translocation histories: first-order populations were those established directly from large source populations, second-order populations were established using individuals from first-order populations, and populations with mixed translocation histories were those established or supplemented with sheep from more than 1 sample on a source population. Nuclear and mitochondrial datasets yielded complementary signals of declining genetic diversity (mixed > first order > second order) that differed predictably in magnitude. Our suite of microsatellites revealed that populations with mixed translocation histories had greater allelic richness (AR) and expected heterozygosity (HE) than second-order populations, but we found no statistical differences between mixed:first order or first:second order population pairs. Mitochondrial diversity, however, was limited to populations with mixed translocation histories. Similarly, we detected significant differentiation (FST) among most populations using data from microsatellites, but found major differentiation in mitochondrial diversity. All first-order and second-order populations shared a single haplotype, whereas mixed populations contained 6 haplotypes. Finally, estimates of effective population size (Ne) derived from our microsatellite data were uniformly low (range 9–27), indicating that the maintenance of genetic diversity in the reintroduced populations of bighorn sheep in our study likely will require management action; possibly including future translocations and improvements in natural connectivity among populations.
Tucker, A. J., Williamson, C. E. (2013), The invasion window for warmwater fish in clearwater lakes: the role of ultraviolet radiation and temperature. Diversity and Distributions. doi: 10.1111/ddi.12138
In clear, cold-water lakes, ultraviolet radiation (UV) and temperature are two important stressors that may prevent the establishment of aquatic invasive species by inhibiting the survival of sensitive early life history stages. In this study, we develop a UV–temperature response model to predict the establishment potential of a warmwater fish, largemouth bass (Micropterus salmoides), in a large subalpine lake based on the ability of bass larvae to tolerate UV and temperature stress along a UV–temperature stress gradient.LocationLake Tahoe (California/Nevada, USA). We compared the UV tolerance of largemouth bass larvae to that of the native redside minnow (Richardsonius egregius) in outdoor UV exposure–response experiments. A UV–temperature response model for larval bass was developed that combined the experimentally derived UV exposure response from our outdoor experiments with a temperature response curve derived from the literature. We used the UV–temperature response model to predict reproductive success (i.e. larval survival) over the range of UV exposure and temperature conditions in nearshore Lake Tahoe. The model predictions were validated with in situ incubation experiments at nearshore locations. Non-native bass were significantly less UV tolerant than native redside minnows. The UV–temperature response model predicted that larval bass survival varies seasonally, spatially and over depth gradients in nearshore Lake Tahoe and is constrained by UV and temperature conditions. In situ incubation experiments confirmed model predictions.Main conclusionsOur findings provide important insights into the potential for species invasion in clear, cold-water lakes that are experiencing significant changes in both temperature and transparency. The conceptual model and approach that we employ is a potentially powerful tool for exploring unanswered questions in invasion biology, including the role of alternate stable states in facilitating invasion and the potential for invasive species to promote ‘invasional meltdown’ through their impacts on water clarity and temperature.
Berg, O. K., Bremset, G., Puffer, M. and Hanssen, K. (2013), Selective segregation in intraspecific competition between juvenile Atlantic salmon (Salmo salar) and brown trout (Salmo trutta). Ecology of Freshwater Fish. doi: 10.1111/eff.12107
Interactive segregation has been suggested as the ruling competition mechanism determining niche and niche segregation between juvenile Atlantic salmon (Salmo salar) and brown trout (Salmo trutta). Results from allopatry–sympatry observations of habitat use in both nature and in experiments were contrary to predictions derived from the interactive segregation hypothesis. Habitat use parameters under natural conditions such as distance to shore for Atlantic salmon parr were nearly identical in allopatric (mean ± SD; 3.2 ± 1.4 m) and sympatric (3.3 ± 1.4 m) situations. Occupied water depths largely reflected available water, but water depths <15 cm were avoided by salmon parr. Under experimental conditions, habitat use of allopatric salmon was density independent and salmon size had only minor effects, with smaller fish being more likely to occur in the shallow. Habitat use of salmon in sympatry with trout did not differ from allopatric salmon habitat use, and only salmon size had minor effects on depth choice – occurrence of trout or fish density had no effect. Allopatric trout was in general more frequent in the shallow habitat than salmon. Habitat use of sympatric trout was affected by the occurrence of salmon and trout size, resulting in a higher use of the shallow habitats for small trout. To conclude, selective segregation has a dominant role in salmon habitat use (not affected by trout occurrence), whereas a mixed situation occurs in trout habitat use with elements of interactive segregation when competing with Atlantic salmon (affected by salmon occurrence). Suárez-Seoane, S., Virgós, E., Terroba, O., Pardavila, X. and Barea-Azcón, J. M. (2013), Scaling of species distribution models across spatial resolutions and extents along a biogeographic gradient. The case of the Iberian mole Talpa occidentalis. Ecography. doi: 10.1111/j.1600-0587.2013.00077.x
Scaling is a key process in modelling approaches since it allows for translating information from one scale to another. However, the success of this procedure may depend on ‘source’ and ‘target’ scales, but also on the biogeographic/ecological context of the study area. We aimed to quantify how the performance and success of scaling species distribution model (SDM) predictions across spatial resolution and extent along a biogeographic gradient using the Iberian mole as study case. We ran separate MaxEnt models at two extents (national and regional) using independent datasets (species locations and environmental predictors) collected at 10 km and 50 m resolutions respectively. Model performance and success of scaling SDMs were quantified on the basis of accuracy measures and spatial predictions. Complementarily, we calculated marginality and tolerance as indicators of habitat availability and niche truncation along the biogeographic gradient. Model performance increased with resolution and extent, as well as from north to south (mainly for high resolution models). When regional models were validated at different scales, their performance reduced severely, particularly in the case of coarse resolution models (some of them performed worse than random). However, when the 10 km-national model was downscaled within regions, it performed better (AUCtest: 0.82, 0.85 and 0.55 respectively for Galicia, Madrid and Granada) than models specifically calibrated within each region at 10 km (0.47, 0.65, 0.44). Indeed, it also had a better accuracy when projected at 50 m (0.77, 0.91, 0.79) than models fitted at that resolution (0.62, 0.83, 0.96) in two of the three cases. The success of scaling model predictions decreased along the biogeographic gradient, being these differences associated to niche truncation. Models representing non-truncated niches were more successfully scaled across resolutions and extents (particularly in areas not offering all possible habitats for species), which has important implications for SDM applications.