bluuebunny/crossref_metadata_2025_split huggingface dataset:
Inter-signal interaction and uncertain information in anuran multimodal signals
Authors: Taylor Ryan C. , Klein Barrett A. , Ryan Michael J. 
Published: February 2016

Abstract
Disentangling the influence of multiple signal components on receivers and elucidating general processes influencing complex signal evolution are difficult tasks. In this study we test mate preferences of female squirrel treefrogs Hyla squirella and female túngara frogs Physalaemus pustulosus for similar combinations of acoustic and visual components of their multimodal courtship signals. In a two-choice playback experiment with squirrel treefrogs, the visual stimulus of a male model significantly increased the attractivness of a relatively unattractive slow call rate. A previous study demonstrated that faster call rates are more attractive to female squirrel treefrogs, and all else being equal, models of male frogs with large body stripes are more attractive. In a similar experiment with female túngara frogs, the visual stimulus of a robotic frog failed to increase the attractiveness of a relatively unattractive call. Females also showed no preference for the distinct stripe on the robot that males commonly bear on their throat. Thus, features of conspicuous signal components such as body stripes are not universally important and signal function is likely to differ even among species with similar ecologies and communication systems. Finally, we discuss the putative information content of anuran signals and suggest that the categorization of redundant versus multiple messages may not be sufficient as a general explanation for the evolution of multimodal signaling. Instead of relying on untested assumptions concerning the information content of signals, we discuss the value of initially collecting comparative empirical data sets related to receiver responses.
Can rarefaction be used to estimate song repertoire size in birds?
Authors: Peshek Kathleen R. , Blumstein Daniel T. 
Published: February 2016

Abstract
Song repertoire size is the number of distinct syllables, phrases, or song types produced by an individual or population. Repertoire size estimation is particularly difficult for species that produce highly variable songs and those that produce many song types. Estimating repertoire size is important for ecological and evolutionary studies of speciation, studies of sexual selection, as well as studies of how species may adapt their songs to various acoustic environments. There are several methods to estimate repertoire size, however prior studies discovered that all but a full numerical count of song types might have substantial inaccuracies associated with them. We evaluated a somewhat novel approach to estimate repertoire size—rarefaction; a technique ecologists use to measure species diversity on individual and population levels. Using the syllables within American robins’ Turdus migratorius repertoire, we compared the most commonly used techniques of estimating repertoires to the results of a rarefaction analysis. American robins have elaborate and unique songs with few syllables shared between individuals, and there is no evidence that robins mimic their neighbors. Thus, they are an ideal system in which to compare techniques. We found that the rarefaction technique results resembled that of the numerical count, and were better than two alternative methods (behavioral accumulation curves, and capture-recapture) to estimate syllable repertoire size. Future estimates of repertoire size, particularly in vocally complex species, may benefit from using rarefaction techniques when numerical counts are unable to be performed.
Avian succession along ecological gradients: Insight from species-poor and species-rich communities of Sylvia warblers
Authors: Guillaumet Alban , Prodon Roger 
Published: February 2016

Abstract
The mechanisms responsible for species replacement during ecological successions is a long-standing and open debate. In this study, we examined the distribution of the Sardinian warbler Sylvia melanocephala along two grassland-to-forest gradients, one in a high-diversity area (Albera-Aspres chain in Catalonia: eight Sylvia warbler species) and one in a low-diversity area (Mount Hymittos in Greece: four species). In Catalonia, distribution models suggested that the apparent exclusion of S. melanocephala from the open and forest ends of the gradient may be explained entirely by the preference of S. melanocephala for mid-successional shrublands. However, a joint analysis of both data sets revealed that: 1) S. melanocephala was more evenly distributed along the vegetation gradient in Greece, suggesting ecological release in the low-diversity area; and 2) a distribution model assuming interspecific competition (based on the distribution of Sylvia species showing a negative co-occurrence pattern with S. melanocephala) had a significantly higher predictive ability than a distribution model based on habitat variables alone. Our study supports the view that species turnover along ecological gradients generally results from a combination of intrinsic preferences and interspecific competition.
Vertebrate species introductions in the United States and its territories
Authors: Witmer Gary W. , Fuller Pam L. 
Published: February 2016

Abstract
At least 1,065 introduced vertebrate species have been introduced in the United States and its territories, including at least 86 mammalian, 127 avian, 179 reptilian/amphibian, and 673 fish species. Examples in each major taxonomic group include domestic cat, small Indian mongoose, red fox, goat, pig, rabbit, rats, house mouse, gray squirrel, nutria, starling, Indian common myna, red-vented bulbul, brown treesnake, red-eared slider, brown trout, tilapia, and grass carp. We briefly review some of these species and the types of damage they cause. We then review the basic types of methods used for control or eradication of each taxonomic group, including physical, chemical, biological, and cultural methods. We discuss some of the challenges in managing these species, including issues with the use of toxicants, land access, public attitudes, and monitoring difficulties. Finally, we list some ongoing research and future research needs, including improved detection methods, improved attractants, improved barriers, improved capture methods, fertility control, and risk assessment methods.
Estimated prevalence of Echinococcus multilocularis in raccoon dogs Nyctereutes procyonoides in northern Brandenburg, Germany
Authors: Schwarz Sabine , Sutor Astrid , Staubach Christoph , Mattis Roswitha , Tackmann Kirsten , Conraths Franz Josef 
Published: February 2016

Abstract
Human alveolar echinococcosis, caused by the larval stage of the small fox tapeworm, is a lethal zoonotic infection if left untreated. E. multilocularis is distributed in the Northern Hemisphere and lives in the small intestines of carnivores, mainly canids. The main definitive host of E. multilocularis in European countries is the red fox Vulpes vulpes and in the last ten years new endemic areas for the parasite in Central Europe have been identified. In some areas, for instance in Germany, the raccoon dog Nyctereutes procyonoides - a spreading neozoon - must be regarded as an additional definitive host for E. multilocularis. In 2001 this parasite was found for the first time in raccoon dogs in the Federal State of Brandenburg, Germany. Between 2000 and 2008, 1,252 raccoon dogs from Brandenburg were examined by the Intestinal Scraping Technique. The majority of samples were obtained in five northern counties and all 60 animals that tested positive for E. multilocularis were located there. The estimated true prevalence calculated by a beta-binomial- model ranged from 6%–12%.
Thermal preference, thermal tolerance and the thermal dependence of digestive performance in two Phrynocephalus lizards (Agamidae), with a review of species studied
Authors: Qu Yanfu , Li Hong , Gao Jianfang , Xu Xuefeng , Ji Xiang 
Published: February 2016

Abstract
We reported data on thermal preference, thermal tolerance and the thermal dependence of digestive performance for two Phrynocephalus lizards (P. frontalis and P. versicolor), and compared data among lizards so far studied worldwide. Mean values for selected body temperature (Tsel) and critical thermal maximum (CTMax) were greater in P. versicolor, whereas mean values for critical thermal minimum (CTMin) did not differ between the two species. The two lizards differed in food intake, but not in food passage time, apparent digestive coefficient (ADC) and assimilation efficiency (AE), across the experimental temperatures. Four general conclusions can be drawn from published data. Firstly, thermal preference and thermal tolerance differ among lizards differing in distribution, temporal activity pattern and habitat use. Lizards in thermally more variable regions are better able to tolerate low and high temperatures. Diurnal lizards generally select higher body temperatures than nocturnal lizards, and lizards using habitats with direct sun exposure generally selected higher body temperatures and are better able to tolerate high temperatures. Secondly, CTMax is positively correlated with Tsel. Lizards more likely exposed to extremely high temperatures while active select higher body temperatures than those using shaded habitats. Thirdly, the effects of body temperature on food intake, food passage time, ADC and AE differ among lizards, but it seems to be common among lizards that ADC and AE are less thermally sensitive than food intake and food passage time. Lastly, ADC is dependent on the type of food ingested, with insectivorous lizards digesting food more efficiently than herbivorous lizards.
Location of rut stands vs. mating opportunities in Przewalski’s gazelle: A field test of the “Resource-based Hypothesis” and “Female Traffic Version of the Hotspot Hypothesis”
Authors: You Zhangqiang , Jiang Zhigang , Li Chunwang 
Published: February 2016

Abstract
We studied the mating tactics of Przewalski’s gazelle on the Qinghai-Tibetan Plateau from 2002 to 2005. Przewalski’s gazelle is a cluster mating animal whereby female groups, including juveniles, travel to and from their resting grounds along fixed routes and dominant males stand on or near these travel routes during rut. To explain rut patterns in male gazelles, we tested predictions arising from the “Resource-based Hypothesis” and “Female Traffic Version of the Hotspot Hypothesis”. We marked the location of each rut stand and female travel route, measured food availability in each rut stand and recorded the mating opportunities of rut stand owners. We also conducted a field experiment to force female groups to change their daily travel route, and observed whether males abandon their original rut stands and shift their rut stands to new travel routes of females during the 3rd rut. We found that: (1) male gazelle defending rut stands closer to a female travel route had a higher chance of mating; (2) food resources within rut stands had no effect on mating opportunities of the rut stand owner; (3) when the female travel route was obstructed, female groups changed grazing sites, and all males abandoned their original rut stands and defended new rut stands along the new female travel route. In conclusion, the location of rut stands in relation to female travel routes is the ultimate factor for consolidating mating opportunities in male gazelle, supporting the “Female Route Version of Hotspot Hypothesis”.
Bioacoustic variation of swimbladder disturbance sounds in Neotropical doradoid catfishes (Siluriformes: Doradidae, Auchenipteridae): Potential morphological correlates
Authors: Kaatz Ingrid M. , Stewart Donald J. 
Published: February 2016

Abstract
Swimbladder disturbance sounds of doradoid catfishes (Doradidae and Auchenipteridae) demonstrated striking waveform and spectrographic variation. We surveyed sounds of 25 doradoid species in 20 genera comparing these to sounds of four vocal outgroup catfish families. Sounds were either continuous waveforms (lacking interpulses) or pulsed (groups of pulses repeated at fixed temporal intervals). This is the first evidence for swimbladder calls with fixed interpulse patterns in catfishes. Vocal mechanism components that were similar between doradids and auchenipterids included: swimbladder shape, swimbladder dimensions and sonic muscle-somatic index. Morphological traits that showed variation among taxa and were evaluated for potential correlates of call diversity are: 1) diverticula (marginal outpocketings of the swimbladder with no connection to inner ear) and 2) elastic spring apparatus Müllerian rami (ESA-Mr). Within the doradid subfamilies and within the Auchenipteridae most species differed significantly in dominant frequency with frequency ranges overlapping to some extent for most. Doradid swim-bladder diverticula did not explain dominant frequency variation within the doradoid superfamily. Some doradids with conical ESA-Mr had the highest dominant frequency sounds. Auchenipterids included both relatively lower and higher dominant frequency sound producers but lacked diverticula and had discoidal ESA-Mr. Comparing a phylogeny of doradoid genera with out-group taxa, we infer that complex diverticula and conical ESA-Mr are derived characters within the Doradidae. Species representing outgroup families produced either continuous lower dominant frequency sounds (aspredinids, mochokids and pseu-dopimelodids) or pulsed higher dominant frequency sounds (pimelodids).
Coat color and its effect on preference for the scent marks of opposite-sex conspecifics in the meadow vole Microtus pennsylvanicus
Authors: Vaughn Ashlee A. , Finger Antedra A. , Gibbs Porshia E. , Ferkin Michael H. 
Published: February 2016

Abstract
Many mammal species can distinguish between opposite-sex conspecifics that differ in a certain trait. In that coat coloration is associated with differences in physiological and behavioral traits, coat color may affect the attractiveness of odor cues produced by conspecifics. Individuals may be able to respond preferentially to conspecifics with a particular coat color. In the present study, we test the hypothesis that scent marks of brown and blond voles differ in their attractiveness to male and female conspecifics. Male voles and brown females did not discriminate between blond- and brown-coated opposite-sex conspecifics suggesting that they are neither selecting potential mates dissociatively nor associatively. However, blond females behaved as if the scent marks of blond males were more attractive than were the scent marks of brown males. Our data suggest that blond females who are already conspicuous to predators, may select blond males as mates because they do not appreciably increase the risk of detection to predators, particularly avian predators. Moreover, because these conspicuous males have survived to mate they may have good genes that reflect their relatively higher quality [Current Zoology 58 (2): 221–227 , 2012].
Discriminative predation: Simultaneous and sequential encounter experiments
Authors: Beatty C. D. , Franks D. W. 
Published: February 2016

Abstract
There are many situations in which the ability of animals to distinguish between two similar looking objects can have significant selective consequences. For example, the objects that require discrimination may be edible versus defended prey, predators versus non-predators, or mates of varying quality. Working from the premise that there are situations in which discrimination may be more or less successful, we hypothesized that individuals find it more difficult to distinguish between stimuli when they encounter them sequentially rather than simultaneously. Our study has wide biological and psychological implications from the perspective of signal perception, signal evolution, and discrimination, and could apply to any system where individuals are making relative judgments or choices between two or more stimuli or signals. While this is a general principle that might seem intuitive, it has not been experimentally tested in this context, and is often not considered in the design of models or experiments, or in the interpretation of a wide range of studies. Our study is different from previous studies in psychology in that a) the level of similarity of stimuli are gradually varied to obtain selection gradients, and b) we discuss the implications of our study for specific areas in ecology, such as the level of perfection of mimicry in predator-prey systems. Our experiments provide evidence that it is indeed more difficult to distinguish between stimuli – and to learn to distinguish between stimuli – when they are encountered sequentially rather than simultaneously, even if the intervening time interval is short.
The reliability of morphometric discriminant functions in determining the sex of Chilean flamingos Phoenicopterus chilensis
Authors: Montalti Diego , Graña Grilli Maricel , Maragliano René E. , Cassini Guillermo 
Published: February 2016

Abstract
Monomorphic birds cannot be sexed visually and discriminant functions on the basis of external morphological variations are frequently used. Our objective was to evaluate the reliability of sex classification functions created from structural measurements of Chilean flamingos Phoenicopterus chilensis museum skins for the gender assignment of live birds. Five measurements were used to develop four discriminant functions: culmen, bill height and width, tarsus length and middle toe claw. The functions were tested on a sample of live flamingos from a zoo. The best classification for museum flamingos was given by a function using tarsus length, bill width and middle toe claw (97%). However, this function did not give the best classification for the zoo-based flamingos (81%) which had the best sex assignment by a function including measurements of tarsus, culmen and bill height and width (85%). This shows that a function giving good results in the sample from which it originated may not be as good when applied to another group of animals. Our study emphasizes the need for assessing the accuracy of a function by testing it with other methods to ensure its suitability when being applied.
The effects of cues from kingsnakes on the reproductive effort of house mice
Authors: Starke W. Wallace , Ferkin Michael H. 
Published: February 2016

Abstract
It is not clear if rodents express inducible defenses in response to reptilian predators such as snakes. We tested the hypothesis that adult house mice Mus musculus decrease aspects of their reproductive effort upon 1 hour of exposure every 48 hours for a 25-day period to the fecal material and shed skins of a euryphagous ophidian predator, the kingsnake Lampropeltis getula, that had been fed mice. We found no significant differences in the total number of offspring born, the number of pups per litter, and the mean weight of pups in litters born to male and female mice that were exposed to predator cues and those mice that were not exposed to such cues. The lack of an inducible response may be associated with the low cost of an effective defense, or the lack of an effective defense against a generalist snake predator.
Speciation by selection: A framework for understanding ecology’s role in speciation
Authors: Langerhans R. Brian , Riesch Rüdiger 
Published: February 2016

Abstract
Speciation research during the last several decades has confirmed that natural selection frequently drives the generation of new species. But how does this process generally unfold in nature? We argue that answering this question requires a clearer conceptual framework for understanding selection’s role in speciation. We present a unified framework of speciation, providing mechanistic descriptions of fundamentally distinct routes to speciation, and how these may interact during lineage splitting. Two major categories are recognized: reproductive isolation resulting from (1) responses to selection, “speciation by selection,” or (2) non-selective processes, “speciation without selection.” Speciation by selection can occur via three mechanisms: (1) similar selection, (2) divergent selection, and (3) reinforcement selection. Understanding ecology’s role in speciation requires uncovering how these three mechanisms contribute to reproductive isolation, and their relative importance compared to non-selective processes, because all three mechanisms can occur side-by-side during speciation. To accomplish this, we highlight examination of groups of organisms inhabiting replicated environmental gradients. This scenario is common in nature, and a large literature illustrates that both parallel and non-parallel responses to similar environments are widespread, and each can result in speciation. This recognition reveals four general pathways of speciation by similar or divergent selection—parallel and nonparallel responses to similar and divergent selection. Altogether, we present a more precise framework for speciation research, draw attention to some under-recognized features of speciation, emphasize the multidimensionality of speciation, reveal limitations of some previous tests and descriptions of speciation mechanisms, and point to a number of directions for future investigation.
Self-referent phenotype matching and its role in female mate choice in arthropods
Authors: Weddle Carie B. , Hunt John , Sakaluk Scott K. 
Published: February 2016

Abstract
A growing body of empirical evidence shows that females of many animal species gain benefits by mating polyandrously, and often prefer to mate with novel males over previous mates. Although a female preference for novel males has been demonstrated for multiple animal taxa, the mechanisms used by females to discriminate between novel and previous mates remain largely unknown. However, recent studies suggest that in decorated crickets Gryllodes sigillatus, females actually imbue males with their own chemical cues, known as cuticular hydrocarbons (CHCs) during mating, and utilize chemosensory self-referencing to recognize recent mates. Here we review evidence that self-referent phenotype matching is a widespread mechanism of recognition in arthropods, and explore how CHCs are used to facilitate mate-choice decisions. There is substantial evidence that CHCs are used as recognition cues to discriminate between species, kin, sexes, mates, individuals, and self and non-self, and are used to facilitate mate-choice decisions in a wide range of arthropod taxa. There is also evidence that CHCs are often transferred between individuals during direct physical contact, including copulation. Chemosensory self-referencing via cuticular hydrocarbons could provide a simple, but reliable mechanism for identifying individuals from previous mating encounters. This mechanism does not require any specialized cognitive abilities because an individual’s phenotype is always available for reference. Given the ubiquitous use of CHCs among arthropods, chemosensory self-referencing may be a widespread mechanism used by female arthropods to facilitate female mate-choice decisions and to enhance opportunities for polyandry.