We analysed sexual dimorphism, various aspects of feeding ecology, and reproductive traits of the grass snake (Natrix natrix) population inhabiting the marshy-swamp ecosystem of Bardača. Through a capture-mark-recapture study, between 2011 and 2014, the first long-term investigations of this snake species were commenced in Bosnia and Herzegovina. A total of 172 adult individuals (96 ♀ : 76 ♂) have been captured and marked. Females reached larger overall body dimensions than males (maximum snout-vent length, SVL, was 994 mm and 640 mm, respectively) and had longer jaws than males of the same body length. On the other hand, tails were relatively longer in males compared to females (22.3% and 19.3% of total body length). Diet analysis revealed yearly differences in qualitative composition of prey, which confirmed intra-population plasticity in the grass snake’s diet. We also found differences in the direction of prey swallowing depending on the prey type (frog or fish): anurans were significantly more often swallowed tail-first, and fish head-first. Also, we found intersexual differences in prey type: females consumed more diverse prey and ate green frogs (Pelophylax sp.) significantly more often. Females reach adulthood at SVL of 62.6 cm and males at SVL of 48.5 cm. Clutch sizes ranged between eight and 28 eggs, and the correlation between female body size and clutch size was positive.

Within-species variation in male morphology is common among vertebrates and is often characterized by dramatic differences in behavior and hormonal profiles. Males with divergent morphs also often use communication signals in a status-dependent way. Weakly electric knifefish are an excellent system for studying variation in male morphology and communication and its hormonal control. Knifefish transiently modulate the frequency of their electric organ discharge (EOD) during social encounters to produce chirps and rises. In the knifefish Compsaraia samueli, males vary extensively in jaw length. EODs and their modulations (chirps and rises) have never been investigated in this species, so it is unclear whether jaw length is related to the function of these signals. We used three behavioral assays to analyze EOD modulations in male C. samueli: (1) artificial playbacks, (2) relatively brief, live agonistic dyadic encounters, and (3) long-term overnight recordings. We also measured circulating levels of two androgens, 11-ketotestosterone and testosterone. Chirp structure varied within and across individuals in response to artificial playback, but was unrelated to jaw length. Males with longer jaws were more often dominant in dyadic interactions. Chirps and rises were correlated with and preceded attacks regardless of status, suggesting these signals function in aggression. In longer-term interactions, chirp rate declined after 1week of pairing, but was unrelated to male morphology. Levels of circulating androgens were low and not predictive of jaw length or EOD signal parameters. These results suggest that communication signals and variation in male morphology are linked to outcomes of non-breeding agonistic contests.

The effects of two contrasting environmental conditions in nearshore waters off central Chile on the diet and morphospace of two cohorts of larval labrisomid blenny Calliclinus geniguttatus were studied using geometric morphometrics and gut content analysis. The two environmental conditions corresponded to (a) a cold period with upwelling-favourable southwesterly winds and a mixed water column of cooler water and (b) a warm period with calm winds and stratified warmer water. During the cold period, fish larvae had a more hydrodynamic head shape, longer jaws and a higher feeding incidence, suggesting a greater food supply due to upwelling events and a possible increase in encounter rates in the turbulent environment. In contrast, the larvae from the warm period had a more robust head shape with smaller jaws and a lower feeding incidence, which was related to higher water temperatures and lower wind intensities. The present study suggests that larvae have a rapid response to environmental changes on a short time scale (i.e., from weeks to months), showing a link between environmental conditions and changes in the phenotypic traits and diet of the larval stages of this cryptobenthic species.

Phenotypic plasticity is a major factor contributing to variation of organisms in nature, yet its evolutionary significance is insufficiently understood. One example system where plasticity might have played an important role in an adaptive radiation is the threespine stickleback (Gasterosteus aculeatus), a fish that has diversified after invading freshwater lakes repeatedly from the marine habitat. The parallel phenotypic changes that occurred in this radiation were extremely rapid. This study evaluates phenotypic plasticity in stickleback body shape in response to salinity in fish stemming from a wild freshwater population. Using a split-clutch design, we detected surprisingly large phenotypically plastic changes in body shape after one generation. Fish raised in salt water developed shallower bodies and longer jaws, and these changes were consistent and parallel across families. Although this work highlights the effect of phenotypic plasticity, we also find indications that constraints may play a role in biasing the direction of possible phenotypic change. The slopes of the allometric relationship of individual linear traits did not change across treatments, indicating that plastic change does not affect the covariation of traits with overall size. We conclude that stickleback have a large capacity for plastic phenotypic change in response to salinity and that plasticity and evolutionary constraints have likely contributed to the phenotypic diversification of these fish.

A combination of morphological and molecular techniques was used to confirm the existence of a second species of the monotypic centrolophid genus Tubbia. Adults of the seamount rudderfish, T. stewarti sp. nov., which reaches about 56 cm SL, is mesopelagic at depths of 525-1438 m in the temperate waters of the Southern Hemisphere. It has a confirmed distribution off Australia and New Zealand where it occurs sympatrically with the wider ranging T. tasmanica Whitley. Like most other members of the group, juveniles live in the epipelagic zone where they have been taken at 30-50 m depth. The new species has a more robust head, more slender body, more flattened interorbit, longer jaws, denser head pores, relatively larger eyes and nostrils, narrower caudal peduncle and more vertebral centra than T. tasmanica, and also differs subtly in some morphometric ratios. A rediagnosis of T. tasmanica is also provided.

Cross-breeding between Janti’s Black Tilapia (female parent) and Janti’s White Tilapia (male parent) has been performed by Institution of Germination and Freshwater Fish Farming which is located at Janti Village – District of Klaten and produced Tilapia Larasati (Red Tilapia Strain Janti) F5. This study aimed to compare the Tilapia Larasati F5 and it parents based on morphometric and meristic characters, and to know the length-weight relationship of three strains of tilapia. Analysis of morphometric characters performed by Principal Component Analysis (PCA) while the meristic character analyzed descriptively by reviewing the literature. Kinship of three strains were tested by cluster analysis while length-weight relationship analysis was conducted to determine the pattern of fi sh growth and condition factor . The scatter plot results of the 12 morphometric characters showed that Tilapia Larasati F5 has a similar body form with Janti’s Black Tilapia and has a slightly different form of Janti’s White Tilapia especially in the part of head. Tilapia Larasati F5 and Janti’s Black Tilapia obtained on a longer body, longer forehead, longer jaw (big mouth), and long face and long nose. It result supported by cluster analysis which showed that Tilapia Larasati F5 has a closer kinship distance to Janti’s Black Tilapia viewed from morphometric characters. Analysis of meristic characters showed that the number of scales on the dorsal fi n in front of the Tilapia Larasati F5 and Janti’s Black Tilapia amounted to more than the Janti’s White Tilapia. Third tilapia strains had isometric growth pattern. Analysis of the value of condition factor indicates that Tilapia Larasati F5 has the best body condition.

Event Abstract Back to Event Androgens regulate differences in chirp duration in the weakly electric fish Parapteronotus hasemani Jacquelyn Petzold1* and G. Troy Smith1, 2, 3 1 Indiana University - Bloomington, Department of Biology, United States 2 Indiana University - Bloomington, Center for the Integrative Study of Animal Behavior, United States 3 Indiana University - Bloomington, Program in Neuroscience, United States Apteronotid electric fish produce a continuous electric organ discharge (EOD) that functions in electrolocation and communication. The frequency and amplitude of the EOD can be modulated during reproductive and agonistic interactions to produce chirps. In several species, EOD frequency and chirping are sexually dimorphic traits that are regulated by steroid hormones (Zakon & Smith, 2009). However, the signal parameters that differ between the sexes vary greatly among species. We tested how EOD frequency and chirping vary between and within sexes in Parapteronotus hasemani, a species of South American weakly electric fish with extreme sexual dimorphism in body size. We performed playbacks of species-typical EODs to male and female P. hasemani to quantify EOD frequency and chirping. EOD frequency, chirp rate, and chirp amplitude modulation were not sexually dimorphic. However, males produced chirps that were longer in duration than those of females. Thus, chirp duration, but not EOD frequency, is a sexually dimorphic trait that may be used as an honest indicator of sex in P. hasemani. As with sexually dimorphic communication signals in many species, sex differences in EODs and chirping in electric fish are often regulated by androgens (Zakon & Dunlap, 1999). We treated male P. hasemani with the androgen receptor blocker flutamide to test whether androgens maintain male-typical chirp duration. Chirp duration decreased significantly in males treated with flutamide but not in males treated with vehicle. This suggests that sex differences in electrocommunication signals in P. hasemani are likely regulated by activational effects of androgens. Jaw morphology varies substantially among male P. hasemani and may be correlated with age or social status (Cox Fernandes, 2010). To determine whether morphological variation in males was associated with variation in gonadal steroid levels, we measured hormones (11KT, T) and morphology (jaw length, body length, and body mass). Unlike other species of fish that have morphologically distinct classes of males (Bass, 1992), larger males with longer jaws did not have higher concentrations of 11KT. Circulating concentrations of T and 11KT were not correlated with jaw morphology, body size, or EOD frequency in males. Additionally, EOD frequency and chirping were not correlated with jaw length or body size. The lack of a correlation of EOD and chirp parameters with hormone levels or morphological traits in males suggests that these signals may not necessarily serve as reliable indicators of male quality. Acknowledgements Supported by NSF IOS 0950721 and the Indiana University Center for the Integrative Study of Animal Behavior. Keywords: electrocommunication, Hormones, sex differences Conference: Tenth International Congress of Neuroethology, College Park. Maryland USA, United States, 5 Aug - 10 Aug, 2012. Presentation Type: Poster (but consider for student poster award) Topic: Hormones and Sex Differences Citation: Petzold J and Smith G (2012). Androgens regulate differences in chirp duration in the weakly electric fish Parapteronotus hasemani. Conference Abstract: Tenth International Congress of Neuroethology. doi: 10.3389/conf.fnbeh.2012.27.00336 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 30 Apr 2012; Published Online: 07 Jul 2012. * Correspondence: Ms. Jacquelyn Petzold, Indiana University - Bloomington, Department of Biology, Bloomington, IN, 47405, United States, jpetzold@indiana.edu Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Jacquelyn Petzold G. Troy Smith Google Jacquelyn Petzold G. Troy Smith Google Scholar Jacquelyn Petzold G. Troy Smith PubMed Jacquelyn Petzold G. Troy Smith Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Species with expanding ranges provide unique opportunities to examine environmentally induced adaptations in ecological traits and anatomical characteristics. Since the late 1800s, the North American red squirrel (Tamiasciurus hudsonicus) has expanded its range into the central hardwoods of the United States in conjunction with increasing agricultural fragmentation. We examined whether red squirrels from the central hardwoods (west‐central Indiana, USA) displayed differences in foraging behaviors and morphology relative to red squirrels from conifer‐dominated environments (upper peninsula of Michigan, USA), a biome in which red squirrels evolved. Specifically, we measured rates of energy extraction, variation in cranial morphology, and diet preference between red squirrels from both regions. In addition, we compared foraging behaviors of red squirrels from the central hardwoods to those of a competitor that coevolved with nut‐producing trees, the gray squirrel (Sciurus carolinensis). Red squirrels from Indiana and Michigan differed significantly in the efficiency with which they used food items, with individuals from each region extracting calories at a more rapid rate for items that were common in their region. The enhanced efficiency of southern red squirrels feeding on black walnuts (Juglans nigra) was correlated with geographic differences in cranial morphology; skulls of southern squirrels were larger, with longer jaws and higher metrics associated with greater mandibular force than northern squirrels. Contrary to our expectations, red squirrels from Indiana and Michigan did not differ qualitatively in preferences for food items, suggesting that diet choice may be governed by perishability of food items rather than by rates of energy extraction. Gray squirrels were more efficient than Indiana red squirrels in using all food items, and differed only slightly from red squirrels with regard to preference for food items. Measures of efficiency of resource use, after accounting for species‐specific metabolic requirements, suggest that red squirrels are unlikely to compensate ecologically for declining gray squirrel populations in fragmented portions of the central hardwoods, with potentially adverse effects for forest regeneration and succession. Our results demonstrate that invading species can display significant flexibility in adapting to new environments, but they may not be flexible enough to exploit resources in a manner comparable to native species.

Abstract We studied the ecology of the checkered garter snake, Thamnophis marcianus, in a desert grassland in southeastern Arizona. The adult sex ratio was 0.67 M:F and varied significantly among seasons. As with other species of Thamnophis, adult females were significantly larger than males in SVL and body mass, and females also had longer jaws. Activity occurred both during the day and nighttime, but was confined to aquatic areas or their immediate vicinity. Mating occurred in late March and females gave birth to a single brood of an average of 15 offspring in late May and early June. The timing of birth in this population was among the earliest on record for any live-bearing snake in North America and was much earlier than for other checkered garter snake populations. In comparison with populations of T. marcianus from northern and southern Texas, females from Arizona had larger maternal body sizes and their offspring were larger as well; conversely, we found no significant differences in brood size am...

The pronounced sexual dimorphism of the chaenopsid Coralliozetus angelica was examined using 37 measurements taken from a size-series ofjuveniles, males and females. A subset of these measurements was used to generate an index of body size by principal component analysis. Each of the 37 measurements was tested for the presence of sexual dimorphism. Osteology and the cephalic sensory pore system were studied using a size-series of cleared-and-stained and intact specimens, respectively. Many dimorphic characters are evident by the onset of sexual maturity (17 and 19 mm SL for females and males, respectively), and all are evident by 21 mm. Males are on average larger than females and have a more robust head, longer jaw, higher dorsal fin, longer supraorbital and nasal cirri, and more palatine teeth. Females have a longer, more pointed pectoral fin, deeper notch in the dorsal fin, longer abdomen, and more precaudal vertebrae. Males develop fused nasals, heavily pitted cranial bones, thick infraorbitals, fused infraorbitals 2 and 3, a fleshy head covered dorsally with muscles, and reduced numbers of cephalic sensory pores. Females are developmentally paedomorphic, resembling juveniles and prematurational males in having separate nasals, smooth cranial bones, three thin infraorbitals, no muscles on the dorsal surface of the neurocranium, and high numbers of sensory pores.

Marmosets have reduced second molars of which size and shape are varied in different species. Mesiodistal and buccolingual diameter of the first and second upper molars in 16 species were measured, and molar area (molar rectangle) and M2 reduction index were calculated by the equation,R=(M2 area/M1 area) × 100. This index ranged from 36.1 inSaguinus oedipus geoffroyi to 70.6 which was the largest found inCebuella pygmaea. Species ofSaguinus showed relatively wide variation as well as a consistantly smaller index. The index forCallithrix registered around 60 andLeontopithecus rosalia was positioned within this genus. There was no relationship between this index and body size of each form. The sizes of the first molar and second molar may not significantly correlate either with body size across species, becauseLeontopithecus rosalia had exceptionally large molars for its body size and contrarily genusSaguinus had relatively small molars. When the shape of the mandible was expressed as length/width ratio, the reduction index significantly correlate with this ratio in genusSaguinus andCallithrix, indicating that longer jaw in shape had relatively large M2. The reduction indices of two possible subspecies,S. oedipus geoffroyi andS. o. oedipus, were 36.1 and 47.3, respectively. This difference suggested that there was a difference in diet or function of jaw apparatus beyond subspecies level.

Viperid snakes have stouter bodies, larger heads, and longer jaws than snakes in other families; there are no major differences between the two subfamilies of vipers in these features. A suite of morphological characters that facilitates swallowing large prey finds its greatest expression among vipers, but certain elapid and colubrid snakes have converged upon the same body form. The number of jaw movements required to swallow prey is linearly related to the size of a prey item when shape is held constant. Very small and very large prey are not disproportionately difficult for a snake to ingest. Vipers swallow their prey with fewer jaw movements than do colubrids or boids and can swallow prey that is nearly three times larger in relation to their own size. Proteolytic venom assists in digestion of prey, and melanin deposits shield the venom glands from light that would degrade the venom stores. Ancillary effects of the morphological features of vipers, plus the ability to ingest a very large quantity of food in one meal, should produce quantitative and qualitative differences in the ecology and behavior of vipers and other snakes.