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Bering Cisco Coregonus laurettae is an anadromous coregonine species known almost exclusively from northwestern North America and with only three documented spawning populations, all in Alaska. Previous studies of Bering Cisco phenotypic variation examined individuals collected primarily in coastal rearing habitats where population affiliation was not known. Here we compare meristic counts and morphometric ratios of pre-spawning adults among the three known populations: one each in the Yukon, Kuskokwim, and Susitna rivers in Alaska. We also compare meristic data with those previously reported for this species. Populations in the Yukon and Kuskokwim rivers were very similar, while the population in the Susitna River was significantly divergent for certain meristic counts and morphometric ratios. Our findings are consistent with recent genetic analyses that found the Susitna River population to be the most divergent of the three populations. While the Yukon and Kuskokwim river populations survived the Wisconsinan Ice Age in the Beringian Refugium, the Susitna River population colonized the drainage following ice retreat sometime in the last few thousand years. The population's divergence from the source population in the Yukon or Kuskokwim river could be due to a founder effect or adaptation to different environmental conditions.
The Eastern Massasauga (Sistrurus catenatus) is a small, grassland-dependent rattlesnake species declining throughout its native range, and is thus a species of high conservation priority. In Illinois, only a single population remains of a once widespread distribution. We documented genetic diversity in this population over a ten-year period and assessed levels of heterozygosity, allelic diversity, inbreeding (FIS), and effective population size (Ne). Neither heterozygosity nor levels of inbreeding differed significantly among periods. We identified 21 alleles that occurred in a single time period, some of which may have been lost from the population given our estimated detection probability of 93%. Effective population size (Ne) was numerically small and showed a decreasing trend through time. Despite small population size and a lack of connectivity, there was no significant decline in genetic diversity over the ten-year study. Aspects of life history, coupled with a preference for a historically patchy habitat, may mitigate the loss of genetic diversity in the species and promote their persistence in the fragmented habitats of the Anthropocene. However, continued genetic monitoring is recommended, and population recovery measures should be implemented as soon as possible to mitigate the deleterious effects of small population size.
The behavioral variation in alligator nest attendance has characterized the species as iconic in common lore and perplexed biologists for decades. Here, we quantify patterns in nest attendance among mothers as well as variation in such patterns throughout two nesting seasons. We employed camera traps controlled by circuit boards to capture time-lapse photographs of alligator nest areas for the duration of each nesting season. Data revealed a bimodal pattern of nest attendance over time that significantly varied across incubation days in both 2011 and 2012, and also differed between years. Nest attendance also differed among hours in the diel cycle, and this pattern was the same for both years. Nest visits were frequent immediately after the eggs were laid, and attendance behavior attenuated rapidly after the first week of incubation. Nest visitation then increased near the end of the incubation period with the largest portion of visits recorded during hatching and the maternal movement of hatchlings away from nest sites. While the extent of this pattern varied between years, the pattern itself did not. The majority of attendance behavior occurred during night hours, with little visitation recorded between 1000 and 1600 hours. Our study is the first to document temporal variation in alligator nest attendances at daily, seasonal, and annual temporal scales, and our findings suggest nighttime visits during oviposition and hatching periods are consistent among years.
Visualizing complex morphological features using digital photographs is often challenging in comparative anatomical studies. Progress in comparative anatomical studies has made substantive shifts through the development of new and improved methods for preparing specimens and visualizing characters. The advent of enzyme-cleared and bone-stained specimens revolutionized comparative anatomical studies in the middle of the 20th century. Continued refinement and improvement on these techniques combined with alternative approaches to visualization have allowed for more detailed investigations of vertebrate anatomy. One of the most difficult challenges remaining in comparative anatomy is accurately communicating morphological variation, and methodological improvements that refine the visual explanation are critical. Here we present two methods that simplify and improve the digital imaging of vertebrate skeletons and their components. First, fluorescence microscopy with alizarin-stained specimens is shown to help identify bony margins, facilitate the identification of skeletal elements in extant and fossil specimens, enhance the light alizarin staining of bone, and differentiate skeletal and soft tissues. Second, the non-permanent mounting of cleared-and-stained vertebrate specimens in a glycerine-gelatin matrix allows researchers to temporarily pose specimens for otherwise impossible scientific or artistic images. These two methods greatly improve researchers' ability to visualize vertebrate specimens or characters they are describing. The improved communication of critical anatomical variation through visual means facilitates the explanations demanded by evolutionary research, specifically, and biology, generally.
While organisms are capable of detecting predators via chemical cues, how well these detection abilities are matched to different historical predation regimes remains poorly understood. The Least Killifish, Heterandria formosa, is a small live-bearing fish whose predominant predators differ among habitats. We performed two experiments to see how H. formosa from different populations respond to a chemical cue from either a familiar predator (abundant in that population's habitat) or novel predator (absent from its habitat but abundant in another habitat inhabited by a different population of H. formosa). Our first experiment compared fish from two populations exposed to a familiar predator, a novel predator, and water from each habitat. Fish from the population with lower historical predation risk were more active regardless of treatment but were especially active when cues from a novel predator were offered. Our second experiment compared fish from four populations exposed to either a familiar or novel predator at the same time. Large fish were more active than small fish and, as in the first experiment, fish from the population with the lowest historical predation risk were more active regardless of the identity of the predator. These results suggest that predator recognition is not specific to individual populations but that historical levels of predation risk have selected for different characteristic levels of activity in different populations.
Groupers (Epinephelidae) are a species-rich assemblage of marine reef fishes whose classification has undergone many changes across various taxonomic levels. Over the past two decades, a number of molecular phylogenetic studies have contributed significantly to clarifying the relationships among groupers; however, usage of the relationships recovered by these studies in the classification of groupers has been inconsistent. In this paper, we build upon the most comprehensive phylogeny for groupers and their allies and use it as a framework for a phylogenetic classification of the group. We correct previous errors or omissions in earlier works and hope to lay to rest any doubts regarding previously proposed classification schemes for groupers. The resulting classification scheme includes nine monophyletic genera and the subsummation of all but one previously monotypic genus.
Organisms with complex life cycles face the challenge of when to switch between habitats and foraging strategies over ontogeny in ways that improve their fitness. Metamorphosis is a well-studied life history event in animals, and ecologists have spent decades trying to understand how the size at and time to metamorphosis are altered by natural stressors such as competition and predation. The challenges in interpreting the effects of predators on metamorphic decisions include the need to compare predator species that pose different levels of risk, compare the roles of predators inducing fear versus thinning of the density of prey, and examine prey life history traits and behavior over ontogeny. We addressed these challenges in a mesocosm experiment in which we introduced a high initial density of hatchling Northern Leopard Frogs (Rana pipiens) and exposed them to three different species of caged predators (to induce three different levels of fear), three rates of hand-thinning (to mimic the thinning effect of each predator), or three species of lethal predators (to cause induction and thinning). Under these initial high densities, we found that caged predators had no effects on tadpole activity, growth, and development. This outcome was likely due to the high density of tadpoles causing high competition, which can inhibit anti-predator responses. High rates of hand thinning caused decreased tadpole activity, greater mass, and faster development. Interestingly, lethal predators caused phenotypic changes that were largely in line with the hand-thinning effects alone. These results suggest that at high initial prey densities, the thinning process of predation appears to play a much more important role in prey metamorphosis than induction from predatory chemical cues.
Lizards at the northern, cool edge of their geographic range in the northern hemisphere should encounter environmental conditions that differ from those living near the core of their range. To better understand how modest climate differences affect lizard energetics, we compared daily feeding and metabolism rates of individual Sceloporus occidentalis in two populations during mid-summer. Chuckanut Beach (CB) was a cool, maritime climate in northern Washington State, and Sondino Ranch (SR) was a warmer, drier climate in southern, inland Washington. We found no difference between populations in daily energy expenditure (DEE), as calculated from doubly labeled water estimates. The CB population, however, had significantly higher prey availability and rate of daily energy intake (DEI) as estimated from fecal pellet masses. Consequently, CB lizards had higher size-adjusted body masses than lizards from SR. Within CB, during midsummer, DEE was similar to DEI. Within the SR population, DEE trended higher than DEI during mid-summer, but was not significantly different. We found no population differences in lizard activity, active body temperature, or preferred body temperature. Hence, we infer the longer activity season for the SR population may compensate for the low food availability and high daily energy cost of midsummer. Moreover, for the CB population, we infer that cooler temperatures and higher food availability allow the lizards to compensate for the shorter activity. We also suggest the CB population may benefit from the predicted warmer temperatures associated with climate change given the similar activity-period body temperatures and DEE between these lizard populations assuming food availability is sufficient.
Life history traits, such as body size and age at maturity, display intraspecific variation across a species' geographic range. Previous studies that examined body size variation among conspecific populations of turtles found that body size generally increases with increasing latitude, with the exception of Wood Turtles (Glyptemys insculpta) and Spotted Turtles (Clemmys guttata), which follow a non-linear relationship with larger body sizes at the two range extremes. Similarly, growth rates are influenced by climatic variables and should display geographic patterns reflective of different environments. The objectives of our study were to a) quantify somatic growth in a northern population of Wood Turtles, and b) determine if the observed geographic variation in body size was the result of interpopulation variation in somatic growth rates. In the northern population, as turtles approached maturity, somatic growth increments varied between the sexes such that on average males grew to larger mean carapace lengths than females within the same number of growing periods, likely indicating the point at which energy is reallocated from growth to reproduction. Populations in the south had relatively higher somatic growth rates, grew to smaller mean carapace lengths, and attained sexual maturity earlier than those at the northern extreme; this pattern was related to the number of frost-free days and temperature. Understanding variation in species' life history traits is critical to understanding changes in population demography, which is important when managing populations that are at risk of extinction.
A new reed snake of the genus Calamaria Boie, 1827, Calamaria andersoni, new species, is described on the basis of a single male specimen collected from Yingjiang County, Yunnan Province, China. The new species can be distinguished from other congeners by the unique combination of the following morphological characters: nine modified maxillary teeth; four supralabials, second and third supralabials entering orbit; one preocular; mental not touching anterior chin shields; six shields and scales surrounding the paraparietal; dorsal scales in 13:13:13 rows; 171 ventral scales; 23 subcaudals; tail slowly tapering anteriorly, then abruptly tapering at tip; dorsal scales reduced to four rows on tail at last two subcaudals; dorsum of body and tail brownish with indistinct narrow black stripes on sides; dark collar on neck absent; light rings/blotches on neck and tail absent; and ventral scales with dark outermost corners. Calamaria andersoni, new species, is the fourth species of the genus recorded from China.
The ability of organisms to respond adaptively to anthropogenic environmental change is behaviorally mediated, and recent studies indicate that anthropogenic acidification impairs behavioral responses by impacting olfactory abilities of aquatic organisms. The effect on behavior of other stressors, such as plant secondary compounds, in concert with low pH, has not been investigated. In this study we sought to a) determine whether the oviposition site choices of adult female Cope's Gray Treefrogs (Hyla chrysoscelis) correspond with the pH and tannin conditions that maximize tadpole survival and performance in the laboratory and b) investigate the impacts of mildly acidic conditions, with and without the added stress of tannins, on the survival, development, and antipredator behavior of this frog's tadpoles. We conducted a field oviposition experiment to determine adult female site choice and reared tadpoles in acidic and tannic conditions to investigate survival and antipredator behaviors. Female oviposition site choice did not correspond with conditions that maximize offspring survival. Acidity did not reduce embryonic (pH = 4.5, 5.5) or larval (pH = 5.5) survival. Tadpole mortality was highest in tannic treatment, yet this treatment received the second most eggs in the oviposition experiment. Some aspects of tadpole antipredator behavior in mildly acidic conditions suggested impaired predator recognition, though this difference was not statistically significant. Tannic conditions appear to have the greatest negative effect on tadpole fitness, and adult females appear to respond maladaptively when offered pools with a tannin concentration likely to be created by some invasive exotic wetland plants.
Local adaptation to an environment can vary across very fine scales—as little as a few meters in some species, kilometers in others. This divergence at microgeographic scales has been linked to dispersal ability and could be responsible for geographic variation in the strength of species interactions. For example, the spread of maladaptive traits across short distances could lead to inferior performance and local extinctions across the landscape. We utilized a model study system (headwater streams of New Hampshire) with known differences in dispersal, gene flow, and intraspecific competition to test for microgeographic variation in interspecific competition. We conducted a common garden experiment and measured survival and growth of larval Spring Salamanders from different stream reaches (fish and fishless) in response to the presence of conspecific salamanders or heterospecific Brook Trout fingerlings. We predicted that Spring Salamanders from reaches with fish would have higher competitive performance with fish than naïve salamanders from reaches without fish. No significant differences were detected in salamander survival. Overall salamander growth was negative but was not affected by reach, heterospecific competitor, or the interaction between those two factors. Based on our results, microgeographic variation does not appear to be important in determining the strength of interactions between larval Spring Salamanders and Brook Trout. Salamander dispersal between our collection reaches is possible, and high gene flow of maladaptive traits could be responsible for the overall negative growth patterns. Our research highlights the importance and complexity of testing species interactions in model systems with known microgeographic variation.
Two new species of Liotyphlops are described from Brazil, one from the Cerrado Biome in central Brazil and the other from the Atlantic Rainforest Biome in south Brazil. The new species are mainly diagnosed by the arrangement of cephalic scales and bones and counts of body scales. High-resolution X-ray computed tomography (HRXCT) was used to present data on the skull of the holotypes. In addition, meristic characters for all species of Liotyphlops are presented in comparison to the new species.
Duas novas espécies de Liotyphlops são descritas do Brasil, uma do Bioma Cerrado no Brasil central e outra do Bioma Mata Atlântica no sul do Brasil. As novas espécies são diagnosticadas principalmente pelo arranjo de escamas e ossos cefálicos e contagens de escamas corporais. Tomografia computadorizada de raios X de alta resolução (HRXCT) foi utilizada para apresentar dados do crânio dos holótipos. Além disso, caracteres merísticos para todas as espécies de Liotyphlops são apresentados em comparação com as novas espécies.
The Mottled Scorpionfish (Pontinus clemensi) is an ecologically and economically important species endemic to the Eastern Tropical Pacific. Despite its importance, little is known about its life history traits. In order to close this knowledge gap, we analyzed otoliths and gonads to describe age and reproduction, fit the von Bertalanffy, logistic, and Gompertz growth models, and selected the most parsimonious model using Akaike Information Criterion. We collected 420 samples from fishing trips throughout the archipelago and fish landed at Pelican Bay dock in Santa Cruz Island from 2013–2015. Fork length of fish ranged from 19–67 cm, with males being significantly larger than females, age ranged from 9 to 17 years (n = 203), with similar ranges for both genders, and the logistic model was the most parsimonious growth model (k5 = 0.46 in males, 0.28 in females, 0.31 for the species). Spawning-capable females were observed in all months, suggesting fish can reproduce year round, with size at first maturity (L90) occurring at 33.6 cm or 11.8 years for females, and 43.4 cm or 13.7 years for males. Our results suggest that, similarly to other species in this family, P. clemensi is a slow-growing fish that begins reproducing later in life. Considering P. clemensi represents an important resource, a management plan should be urgently introduced to ensure a sustainable fishery and the survival of the population.
Conservation and management of cryptic species is particularly challenging since it can be difficult to determine their exact distributions. Knowledge of species distribution is required to recognize management units based on taxonomy and whether there are any pertinent biogeographic patterns that could be relevant to the development of a management plan. Such a situation exists in Illinois with the Rosyface Shiner Notropis rubellus and Carmine Shiner Notropis percobromus. There are no reliable anatomical characters to distinguish between the two species. Instead, they are distinguished by genetic data. Samples were obtained for these two species from across the state from each major watershed in which they are found. Based on cytochrome b sequence variation the two species can be distinguished by 44 species-distinct differences. Notropis percobromus is restricted to the Rock River watershed and nearby Mississippi River tributaries in northwest Illinois. Notropis rubellus is found in the Illinois River basin and Vermilion-Wabash watershed. This is a reflection of historical drainage patterns from the geologic period when eastern Illinois was connected to the Great Lakes, as opposed to today when all the rivers in this study are part of the Mississippi basin. Using a previously published rate of divergence of the cytochrome b gene, we estimated a divergence time for these two species that was consistent with a previous estimate—2.8–2.6 MYA. Statistically, there was no genetic difference among populations within N. rubellus or N. percobromus. Haplotype networks and a phylogenetic analysis do provide some evidence for potential bottlenecks/founder effects and/or haplotype-specific selection within each species.
The spatial patterns of feces deposition have been well studied in many terrestrial organisms, while few studies have examined these behaviors in marine fishes. Territorial animals tend to feed within their respective territories. Thus, individuals are faced with the decision of defecating within their territory, where they live and feed, or outside where they are potentially more susceptible to predation. In this study, we conducted behavioral observations on three species of damselfishes to quantify defecation rates and to investigate the spatial distribution of defecation events relative to territory location on Caribbean coral reefs. Defecation rates were low in the early morning and steadily increased throughout the day, peaking in the late afternoon. All 108 observed defecation events occurred outside of the territory. Additionally, 73% of individuals (n = 52) utilized the same location in successive defecation events, which is a significant departure from what would be expected were they defecating in randomly selected locations. Daily defecation rates follow previously determined rates for diurnal coral reef fishes and are closely linked to feeding behavior. However, the spatial patterns of damselfish defecation are likely related to territory maintenance, predator avoidance, or parasite avoidance. This is only the second study to investigate the spatial distribution of fecal matter in damselfishes.
Many amphibians use multiple habitats across seasons. Information on seasonal habitat use, movement between seasonal habitat types, and habitats that may be particularly valuable is important to conservation and management. We used radio-telemetry to study late-season movement and habitat use by Oregon Spotted Frog (Rana pretiosa) at nine sites from four populations along the Cascade Mountains in Oregon. Movement rates declined with date and were the lowest at the end of tracking in December and January. Frogs across our sites used vegetated shallows in late summer and early fall. In fall, frogs used a range of habitat types, and at several sites moved to distinctive habitats such as springs, interstices in lava rock, and semi-terrestrial beaver channels. Distance between first and last tracking location was <250 m for 84.5% (49/58) of frogs, ranged up to 1145 m, and was greater for frogs in ditch habitats than those not in ditches. Distinctive features like springs or semi-terrestrial retreats can host multiple frogs and may represent particularly valuable wintering habitat for R. pretiosa in some sites in their Oregon range.
Morphological variation between closely related island endemics offers a unique system to study ecological and evolutionary processes. The Island Night Lizard, Xantusia riversiana (Cope, 1883), is endemic to three of the Southern Channel Islands off the coast of Southern California: Santa Barbara, San Clemente, and San Nicolas. Some authors treat the species as polytypic with the night lizards on San Nicolas (X. r. riversiana) distinct from those on Santa Barbara and San Clemente (X. r. reticulata). Previous studies failed to find strong morphological divergence, but it remains uncertain if those studies were hampered by a combination of small sample size, small number of characters, and/or the lack of modern morphometric techniques. Here we examined 172 Island Night Lizards from the three islands for nine morphometric and five meristic characters, increasing the number and types of morphological characters examined over previous studies and applying modern morphometric techniques to test for divergence associated with island and sex. We found significant differences in both body measurements and meristic characters among the nominal subspecies as well as among the three islands. We also detected significant sexual dimorphism in body and scale characteristics for both subspecies. However, assigning individuals to an island based on morphology is difficult because all three islands harbor morphologically overlapping individuals. Our study clarifies Island Night Lizard systematics, as well as informs conservation efforts for an island endemic that was until recently listed as threatened under the U.S. Endangered Species Act.