Non-gravid Females Research Articles

The Spatial Ecology of the Eastern Massasauga (Sistrurus c. catenatus) in Northern Michigan

We investigated the spatial ecology of the eastern massasauga (Sistrurus c. catenatus) at a study site unique in that it was near the northern extent of the species' geographic range and had a sandy substrate and extensive mixed coniferous forest. Forty-six individuals were radiotracked for at least one complete season between 2002 and 2004 or 2006 and 2007. Males had larger home ranges and core areas, range lengths, and movement rates than nongravid females, which in turn had larger movement parameters than those of gravid females. Movement rates and distances were not constant throughout the activity season, with males making greater movements as the activity season progressed and gravid females making the longest movements immediately following parturition. Total area used during the activity season was intermediate relative to that used by massasaugas at other sites, with minimum convex polygons around outermost observations during the active season averaging 16.7 ha. Movement indices at our site were much larger than reported indices from study sites in the central or southern portions of the massasauga's geographic range and more similar to those from Ontario and New York. The trend for increased movements at northern latitudes may have implications for managers attempting to provide sufficient habitat for viable populations and minimize interactions between snakes and roads or other anthropogenic disturbances.

Description and life cycle of Bathylaimus anatolii sp.n. (Nematoda, tripyloididae)

Bathylaimus anatolii sp. n. is described and illustrated. The new species resembles B. capacosus Hopper, 1962 but differs from the latter by shorter setae, body and by the c-index and has three onchs in the buccal cavity. The seasonal dynamics of abundance, proportion of adults and larvae, as well as the gravid and nongravid females and males were studied. An elongated breeding season from April to November and a long spring-summer peak of population density with a winter minimum at low temperatures for B. anatolii are characteristic in Peter the Great Bay.

Sex- and maturity-based differences in movement and migration patterns of grey nurse shark, Carcharias taurus, along the eastern coast of Australia

Photo-identification techniques were used to investigate temporal and spatial distributions of Carcharias taurus (Rafinesque, 1810) in relation to maturity, sex and pregnancy status at 19 sites along Australia’s eastern coastline. Of 931 individual sharks identified between 2004 and 2008, 479 were female (271 mature, 208 immature) and 452 male (288 mature, 164 immature). Mature, non-gravid females and mature males were mostly observed in the southern to central parts of this species range, along the eastern coast of Australia, in early summer to early winter. These sharks subsequently moved northward, and mating occurred in late spring to early summer in waters off the coast of northern New South Wales and southern Queensland. Pregnant C. taurus aggregated at Wolf Rock in southern Queensland, at the most northerly part of their known range, from late summer to early winter. These sharks subsequently migrated south to pup in central and southern waters of their range in late winter to late spring. Immature sharks of both sexes moved less than mature sharks, showed no synchronised migration patterns, and were mostly restricted to central and southern waters. The improved understanding of sex- and maturity-based migration of C. taurus provided here should facilitate a conservation strategy appropriate for this species in Australian waters.

Ionic Composition and Ion Provisioning in Marsupial Fluid of Terrestrial Isopods (Isopoda, Oniscidea)

Abstract The marsupium of the primarily terrestrial isopod sub-order Oniscidea is modified from the basal marine design and represents one of the key evolutionary innovations enabling the invasion of land habitats. In the Ligiidae, the marsupial chamber is provisioned with water from the external environment via a capillary channel formed from the apposed 6th and 7th pereiopods. The other oniscidean families possess a 'closed' marsupium, isolated from the pleural water-conducting system and provisioned with water and ions by sternal cotyledons. How these different modes of fluid provisioning influence the ionic composition of marsupial fluid and its osmotic and ionic relationship to the haemolymph remains essentially unstudied. We analysed the ionic composition (Na+, K+, Ca2+, Cl–, pH) of marsupial fluid and haemolymph in 4 species of Oniscidea: Ligia occidentalis (Ligiidae), Ligidium lapetum (Ligiidae), Alloniscus perconvexus (Alloniscidae), and Armadillidium vulgare (Armadillidiidae). In all four species, ion concentrations show a broad similarity between marsupial fluid and haemolymph, but with elevated potassium concentrations in the 'closed'-marsupium species. The sternal integument of Armadillidium vulgare is permeable to inulin and the volume of the combined marsupial fluid and haemolymph is not significantly enlarged compared to the haemolymph of non-gravid females. Accordingly, the 'closed' marsupium of A. vulgare can be viewed as a functional subdivision of the haemolymph space. In Ligidium lapetum, marsupial water is derived from external freshwater sources, but marsupial fluid [Na+] and [Cl–]are actually significantly higher than haemolymph values. This species thus possesses an effective means of ion provisioning, paralleling that seen in the 'closed' marsupial species.

Effects of Maternal Status on the Movement and Mortality of Sterilized Female White-Tailed Deer

Surgical sterilization by tubal ligation has been proposed as a technique for controlling white-tailed deer (Odocoileus virginianus) populations in urban or suburban areas where other forms of population control are impractical, but little is known about demographic rates in populations under management with surgical sterilization. We analyzed seasonal movement and mortality data collected during a 4-year study of surgical sterilization in suburban Chicago, Illinois, USA. We calculated 323 home range size estimates for 62 individual females within season and year. Non-gravid females without young exhibited home range sizes 52% larger than gravid females and females with fawns. Mortality rate was positively correlated with home range size. We suggest that the increased mortality rate observed in surgically sterilized females may be due to greater movement by non-maternal females. Population managers will need to account for potential effects of maternal status on movement and mortality when considering the use of sterilization for management of suburban populations of white-tailed deer.

Seasonal Occurrence of Activity and Reproduction of the Three-Toed Box Turtle (Terrapene Carolina Triunguis) in East Texas

North American box turtles (Terrapene spp.) typically demonstrate localized activity patterns that are highly dependent on temperature and precipitation. In east Texas, we found no documented reports of activity patterns, clutch sizes, sex ratios, or ratios of gravid to non-gravid females in T. Carolina triunguis. Here, we report data on the monthly occurrence and reproductive status for a population of T. c. triunguis in Walker County, Texas. We used a volunteer sampling protocol to investigate when males and females were most active. April and May had the greatest frequency of captures while June and July had the least. Captures were slightly male-biased (1.6 males: 1 female) and the first gravid female was collected on April 29. About half (54%) of all females x-rayed were gravid with clutch sizes ranging from one to five eggs. The variation in the clutch size of eggs is explained by female body mass with larger females having larger clutches of eggs. The activity and reproductive patterns reported here are similar to those patterns documented in past studies and other Terrapene populations, but provide what may prove to be useful natural history information for an urban population of T. c. triunguis.

Relationship of larval desiccation to Anopheles gambiae Giles and An. arabiensis Patton survival

Relationship of larval desiccation to Anopheles gambiae Giles and An. arabiensis Patton survival

Do alternate escape tactics provide a means of compensation for impaired performance ability?

Whole-animal performance abilities can facilitate the avoidance of predation and consequently influence fitness, but determining the functional significance of antipredation tactics is difficult without understanding how alternate predator escape strategies are related. We measured maximal sprint speed and dive duration in the semi-aquatic skink Oligosoma suteri to determine how morphology and behaviour influence these alternate predator escape techniques and the relationship between the two measures. Gravid females and juveniles ran significantly slower, but had equivalent or longer dive durations than males and nongravid females. The two performance measures were not influenced by the same morphological and behavioural traits, and were not correlated among individuals. Thus, individuals that are poor sprinters because of their state (e.g. gravid or tail-less individuals) would have a greater likelihood of successful escape by adopting an alternate escape strategy. For species that use multiple strategies for the same function, quantifying selection on whole-animal performance will be difficult. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 99, 241–249.

Effects of incubation temperature on hatchling phenotypes in an oviparous lizard with prolonged egg retention: are the two main hypotheses on the evolution of viviparity compatible?

Effects of incubation temperature on hatchling phenotypes in an oviparous lizard with prolonged egg retention: are the two main hypotheses on the evolution of viviparity compatible?

Amphibian Chytridiomycosis in the Oregon Spotted Frog (RANA PRETIOSA) IN WASHINGTON STATE, USA

In recent years Batrachochytrium dendrobatidis (Bd), a chytridiomycete fungus pathogenic to amphibians (Longcore and others 1999), has been implicated as the proximate cause of amphibian declines around the world (Berger and others 1998; Daszak and others 2003; Muths and others 2003; Pounds and others 2006). Despite the insidious nature of Bd (Green and others 2002), few published data exist addressing its occurrence in the Pacific Northwest (PNW). When Pearl and others (2007) opportunistically examined 7 PNW amphibian species, they found Bd most often (57% of 21 individuals from 14 sampled populations) in the highly aquatic Oregon Spotted Frog (Rana pretiosa), an Endangered Species in Washington State (WDFW 2009). However, all R. pretiosa they sampled were from Oregon, and Bd was not detected in the Rana cascadae (Cascades Frog) and Anaxyrus boreas (Western Toad) specimens they sampled from Washington. Here, we report the detection of Bd in R. pretiosa from Washington. Since 1997 and 1998, respectively, we have been monitoring R. pretiosa populations at the Trout Lake Natural Area Preserve (TLNAP: UTM Zone 10, 610857-612950E, 5095880-5097574N, WGS84; elev. 594 to 599 m) and Conboy Lake National Wildlife Refuge (CLNWR: UTM Zone 10, 625223-635180E, 5086652-5095491N, WGS84; elev. 552 to 576 m), in Klickitat County, Washington. These sites represent 2 of only 3 areas where R. pretiosa is known to occur in Washington (McAllister and Leonard 1997). At both sites, monitoring included egg mass surveys during the annual breeding season following snowmelt (late February to mid-March at CLNWR; midMarch to early April at TLNAP). Surveys involved area-specific counts of individual egg masses and egg mass groups, each of which was marked with flags and geo-referenced using a Geographic Positioning System (GPS) to avoid double-counting. Sampling at CLNWR addressed 4 hydrologically distinct units, which were surveyed repeatedly until no new egg masses were found; at TLNAP, 3 units consistently used for breeding were sampled. We inferred a 1:1 correspondence between egg mass numbers and number of breeding females based on a combination of our direct observations of oviposition (n 5 13), the recapture of non-gravid females known to have laid eggs (n 5 84), and the relatively short interval over which the laying of new egg masses occurs (about 3 wk). Collectively, these data indicate that females lay only 1 clutch annually, and that egg mass numbers reflect the effective population numbers of adult females. Decline in egg mass numbers in 3 of the 4 surveyed units at CLNWR from 2004 to 2005 (Fig. 1) and 2 of the 3 units at TLNAP over the same period (Fig. 2), coupled with the increasing recognition of Bd as a cause of amphibian declines, motivated us to collect dead frogs found during 2006 and test them for Bd. Five dead adult R. pretiosa were tested for Bd; 1 from CLNWR and 4 from TLNAP. The CLNWR specimen collected on 13 March 2006 displayed feeble vital signs, minimal response to touch, and righting response was lacking. The frog died within 20 min of discovery, was preserved in 10% formalin, and then stored in 70% ethanol before histological examination using a standard wet-mount preparation of its epidermal tissue (Berger and others 1999), which was sloughing extensively as multiple epidermal layers. A dead adult female R. GENERAL NOTES

Timber Rattlesnakes (Crotalus horridus) Exhibit Elevated and Less Variable Body Temperatures during Pregnancy

Body temperatures of ectotherms critically affect their bioenergetics, and thus have consequences for multiple aspects of population ecology, including recruitment, survival, and population viability. We compared body temperatures and movement between gravid and non-gravid female Timber Rattlesnakes (Crotalus horridus) inhabiting northwestern Arkansas using radiotelemetry. Body temperatures (n = 839) were recorded from six gravid and five non-gravid adult female rattlesnakes using temperature-sensitive radiotelemetry. Mean Tbs were calculated for each hour of the day from 15 July–22 August 2002 and used to construct a representative 24-hour body temperature profile. Gravid females had significantly higher mean Tbs in the early morning and again for most hours in the late afternoon and first half of scotophase. Overall snake Tbs were higher during the day and lower at night. Moreover, gravid females exhibited lower variation in Tb during late afternoon than did non-gravid females. Mean area used (± SD) by gravid females (0.4 ± 0.4 ha) was significantly less than that of non-gravid females (2.4 ± 1.8 ha), and daily movement (18.2 ± 6.1 m/day) and overall distance traveled by non-gravid females (827.4 ± 234.4 m) was over twice that of gravid females (8.8 ± 4.6 m/day; 384.0 ± 236.1 m). Understanding the thermal ecology of reproduction in this viviparous capital breeder provides valuable information for habitat management and species conservation.

Food Habits of the Plains Garter Snake (Thamnophis radix) at the Northern Limit of Its Range

The North American genus Thamnophis is a widely distributed and abundant group of snakes. Previous research has indicated that most garter snakes are generalist predators that largely consume anurans, with some degree of geographic and temporal plasticity in response to resource variation. We studied the dietary habits of the Plains Garter Snake, Thamnophis radix, based on stomach contents from 548 animals collected in the field from 1995-2006 at the northern limit of the species' range in central Alberta, Canada. Feeding frequency overall was low (22%) and was highest in spring and early summer. Diet was composed mainly of anurans (85%), especially Wood Frogs (Rana sylvatica) and Boreal Chorus Frogs (Pseudacris maculata), and occasionally invertebrates (10%) and small mammals (5%). Small snakes (<200 mm) began feeding shortly after birth and consumed mainly smaller frogs. Larger snakes ate a wider range of prey sizes and types, but frogs still constituted the majority of prey consumed. Despite sexual size dimorphism, males and females ate prey of the same size and type; however, gravid females contained food less frequently than both males and nongravid females. This study adds to the growing number of dietary studies on T. radix and provides additional evidence for the ecological plasticity of Thamnophis species. Further studies are needed to examine how important these snakes are as components of wetland food chains.

The Physiological Cost of Pregnancy in a Tropical Viviparous Snake

During pregnancy, the metabolic rate of females may increase above basal levels to support metabolically active tissues and developing embryos. In mammals, this energetic cost of supporting the pregnancy (MCP) is an important component of reproductive effort, but less is known about the magnitude of this cost in ectothermic vertebrates. We estimated the metabolic cost of supporting pregnancy in a tropical viviparous snake, the Northern Death Adder, Acanthophis praelongus. We measured the metabolic rates of non-gravid and gravid females throughout gestation and following parturition. We also measured the oxygen consumption of a sample of neonates from each clutch within 24 h of birth. The metabolic rate of gravid females rose slowly during pregnancy, but was significantly elevated during the last three weeks of gestation. Considering the late term metabolism of gravid females as 100%, then the baseline metabolism of female Death Adders represented 36.6%, embryo metabolism accounted for 37.0%, and the cost of supporting the pregnancy was 26.4% of the total metabolic rate. Neonate metabolism during the first 24 h of birth was 2.9 times higher than the estimate for embryo metabolism. Thus, our results do not support the assumption that the metabolism of embryos (prior to birth) and neonates is similar in this species. Although gravid female Death Adders maintain high and constant body temperatures during late gestation, the energetic cost of supporting the pregnancy is only a minor component of the total reproductive effort for females of this species.

The Effect of Reproductive Condition on Thermoregulation in Female Agkistrodon piscivorus Near the Northwestern Range Limit

Females of some temperate-zone snake species appear to exhibit thermophilic behavior during gestation, resulting in differential habitat use between gravid and nongravid individuals. We investigated thermoregulation of 13 female cottonmouths (Agkistrodon piscivorus) near their northwestern range limit in southwestern Missouri during mid-summer. Mean preferred body temperature (23.4 C) and preferred body temperature range (Tset, 20.0-26.5 C) measured in a laboratory thermal gradient were lower than those reported for most snake species. Physical models demonstrated that Tset consistently was available to snakes during the study period, although the frequency of availability varied among habitats. The relatively high thermal quality of the environment (based on Tset availability) allowed snakes to achieve field body temperatures (Tb) closely matching laboratory preferences. Gravid females exploited the thermal environment more efficiently than nongravid females by preferentially occupying the most thermally favorable microhabitats. Accordingly, gravid females consistently maintained higher Tb than nongravid females, demonstrating a functional link between habitat use and thermoregulation. Differences in Tb between gravid and nongravid females were greatest at low ambient temperatures, highlighting their different thermoregulatory strategies. Maintenance of low Tb in nongravid females is consistent with an energy conservation strategy benefiting reproductive investment.

Effect of 17β-estradiol and progesterone on vitellogenesis in the spotted ray Torpedo marmorata Risso 1810 (Elasmobranchii: Torpediniformes): Studies on females and on estrogen-treated males

Effect of 17β-estradiol and progesterone on vitellogenesis in the spotted ray Torpedo marmorata Risso 1810 (Elasmobranchii: Torpediniformes): Studies on females and on estrogen-treated males

Evaluation of a nonlethal technique for determining sex of freshwater mussels

Abstract The shells of most North American freshwater mussel species are not sexually dimorphic. During the brooding period, gravid females can be identified by inspection of marsupial gills; however, it is difficult to separate nongravid females from males in species lacking sexual dimorphism. The ability to differentiate males from females throughout the year would assist mussel conservation and research. Our objective was to test the accuracy and safety of a method to determine the sex of live mussels. We used a syringe to extract ∼0.2 mL of gonadal fluid from 67 Elliptio dilatata and 65 Actinonaias ligamentina. The fluid was stained and examined microscopically for developing gametes. This method was safe and effective for determining the sex of mussels. After 1 y, survival was indistinguishable between test and control groups for both species. We sacrificed 4 to 7 E. dilatata and A. ligamentina at 3-mo intervals and examined histological sections of gonads. Sex assigned from examination of gonadal flu...

Microhabitat Specificity of Paulisentis missouriensis (Acanthocephala) in Creek Chub (Semotilus atromaculatus) in Southeastern Nebraska, U.S.A.

Microhabitat specificity of Paulisentis missouriensis (Acanthocephala) in the intestine of creek chub (Semotilus atromaculatus) was studied. Data from 64 naturally infected fish harboring only P. missouriensis were utilized to determine if site specificity of worms varied by sex, size, and reproductive maturity, and to test the hypothesis that the first flexure of the intestine of creek chub is the preferred microhabitat, as reported in the literature. Location of worms within the intestine did not differ among size classes of either female or male worms. However, gravid female worms occupied intestinal segments around the first flexure of the intestine, whereas nongravid females were concentrated in the posterior part of the intestine around the second flexure. The distribution of males coincided with that of gravid females. These data suggest that P. missouriensis initially establishes in the posterior regions of the intestine of creek chub, after which they move anteriorly, mate, and come to occupy positions centered around the first flexure of the intestine.

MALE RED-BACKED SALAMANDERS CAN DETERMINE THE REPRODUCTIVE STATUS OF CONSPECIFIC FEMALES THROUGH VOLATILE CHEMICAL SIGNALS

Previous research suggests that female red-backed salamanders (Plethodon cinereus )i n Virginia court biennially whereas males court annually. Therefore, males may face a choice to court either gravid or nongravid females. Because gravid females represent an immediate insemination opportunity (whereas nongravid females do not), male red-backed salamanders may be under selection to be able to distinguish the reproductive status of conspecific females. We conducted an experiment to determine if males could discriminate between gravid and nongravid conspecific females through volatile chemical signals. Focal males were allowed to establish territories in testing arenas for 5 d and then were exposed to three treatments in a randomized order: volatile chemical signals from gravid females, nongravid females, and a control (blank filter paper). Randomization tests revealed that focal males exhibited significantly more aggressive behavior when they were exposed to volatile chemical signals from nongravid females than when they were exposed to those from gravid females and the control. We infer that male red-backed salamanders can determine the reproductive status of conspecific females through volatile chemical signals, which may influence their social associations.

Movements, Home Ranges, and Capture Effect of the Endangered Otago Skink (Oligosoma Otagense)

Otago Skinks (Oligosoma otagense) are some of New Zealand's largest and most rare lizards. The movements and home ranges of these skinks were investigated using radio-telemetry at the Redbank Reserve near Macraes Flat, Central Otago, New Zealand. Thirteen Otago Skinks were tracked from December 2003 through April 2004 for 26–111 days. There was no significant difference in the distance or frequency of movements between sexes. Home ranges estimated for all individuals using the 100% Minimum Convex Polygon method varied from 200–5,400 m2. Male home ranges were significantly larger than female home ranges, and nongravid females had significantly larger home ranges than gravid females. There was a considerable amount of home-range overlap and interaction between individuals. Human capture of skinks, the most common method for the monitoring this species, increased the frequency of movements. Capture-induced disturbance caused skinks to increase the frequency of movements in the days immediately following the event. The results of this study will be used in the future conservation management of the Otago Skinks.

Evolution of viviparity in warm‐climate lizards: an experimental test of the maternal manipulation hypothesis

The maternal manipulation hypothesis for the evolution of reptilian viviparity has been claimed to apply to any situation where gravid females are able to maintain body temperatures different from those available in external nests, but empirical data that support this hypothesis are very limited. Here, we tested this hypothesis using gravid females of a warm-climate lizard, Mabuya multifasciata, by subjecting them to five thermal regimes for the whole gestation period. We found gravid females selected lower body temperatures and thermoregulated more precisely than did nongravid females. Offspring produced in different treatments differed in head size, limb length and sprint speed, but not in overall body size or mass. Variation in morphological traits of offspring was induced primarily by extreme temperatures. Sprint speed of offspring was more likely affected by the mean but not by the variance of gestation temperatures. Gravid females maintained more stable body temperatures than did nongravid females not because these temperatures resulted in the optimization of offspring phenotypes but because the range of temperatures optimal for embryonic development was relatively narrow. Our data conform to the main predictions from the maternal manipulation hypothesis that females should adjust thermoregulation during pregnancy to provide optimal thermal conditions for developing embryos and that phenotypic traits forged by maternal thermoregulation should enhance offspring fitness.