Vent Length Research Articles

The Composition and Function of Intestinal Microbiota Were Altered in Farmed Bullfrog Tadpoles (Aquarana catesbeiana) during Metamorphosis

The bullfrog Aquarana catesbeiana is one of the main farmed frog species in China, with a low overall survival of farmed bullfrogs from hatching to harvest since bullfrog tadpoles are fragile during the metamorphosis period. The intestinal bacterial community can play crucial roles in animal development; however, little is known about the alteration of the gut microbial community of A. catesbeiana during metamorphosis. The present study used 16S rRNA amplicon sequencing to investigate the intestinal bacterial community in A. catesbeiana at four distinct developmental stages. Moreover, we determined the bullfrog’s body morphological parameters and the intestine histology at different developmental stages. The results showed a reduction in the total length and snout–vent length of A. catesbeiana during metamorphosis. The intestinal microbial composition of A. catesbeiana exhibited variation throughout the process of metamorphosis. The terrestrial stage showed shifts in the bacterial composition compared to the aquatic stages, including a reduction in Bacteroidetes and an increase in Firmicutes. Furthermore, the presence of Prevotella, Bifidobacterium, Leucobacter, Corynebacterium, Bulleidia, Dorea, Robinsoniella, and Clostridium in A. catesbeiana metamorphosis appears to be mainly related to the host’s epithelial cells’ height and total body mass. The results indicated that the intestinal microbial composition changed with the bullfrog–tadpole metamorphosis. The genera of Prevotella, Bifidobacterium, Leucobacter, Corynebacterium, Bulleidia, Dorea, Robinsoniella, and Clostridium might be potential probiotics.

A new species of colorful Platypelis (Amphibia: Microhylidae) from the Tsaratanàna and Bemanevika massifs in northern Madagascar

Frogs of the genus Platypelis are known to have their center of species richness in the mountain massifs of northern Madagascar. We here formally describe a new species of Platypelis from this region. Platypelis saikamavo sp. nov. has been known for over 20 years but its taxonomic identity has only recently been robustly clarified as a result of ongoing taxonomic revisions of other Platypelis species. The new species is known from rainforest on the Tsaratanàna Massif and Bemanevika, at elevations of 1000–1530 m above sea level. It is characterized by an isolated phylogenetic position and is genetically highly divergent, with an uncorrected pairwise distance ≥4.5% in the mitochondrial 16S rRNA gene to all other nominal species of Platypelis. It has a unique combination of morphological and chromatic character states such as a relatively large body size of 28–31 mm in snout–vent length, distinct superciliary tubercles, and bright yellow color around the forelimb insertion and on the posterior abdomen where this color extends in the form of flash marks onto the inguinal region.

Prevalence of injuries in a Caiman crocodilus chiapasius (Bocourt 1876) population from the South Pacific coast of Mexico

ABSTRACT Crocodilians injuries are indicators of their health and social interactions. We analyzed the prevalence and distribution of injuries in spectacled caiman (Caiman crocodilus chiapasius) from the Biosphere Reserve of La Encrucijada (BRLE) in relation to the habitat, size, and sex of individuals. We collected data on injuries in caimans captured during nocturnal surveys (2014–2022) in the estuary and swamps of the BRLE. We determined the sex of each caiman, measured their snout–vent length, and registered the type of injury and body region where injuries were detected. From all records, 102 of 301 caimans (33.9%) presented injuries and they were more likely to be injured in the estuary than in the swamps, probably due to the presence of a larger sympatric crocodile species in the estuary (Crocodylus acutus). Sex had no effect on the proportion of injured individuals, but larger caimans have a higher probability of being injured than smaller ones, explained by an ontogenetic change in the individuals’ behaviors. Habitat, sex, and size class of individuals do not influence the number of injuries on different body regions. The tail was the most injured body region (17.6% of individuals), followed by the abdomen (13.0%), back (12.6%), head (9.6%), and extremities (4.0%).

Reproductive output in a small Mediterranean lizard, the western three-toed skinks Chalcides striatus

Abstract The Western Three-toed Skink (Chalcides striatus) is a viviparous species found in arid Mediterranean climates. Using artificial shelters, we captured five pregnant females (snout vent length = 139.2 ± 7.9 mm [SD], 131 to 150 mm; total length = 286.0 ± 9.6 mm, 275 to 292 mm [N = 3, two females with damaged tails]); body mass 15.72 ± 3.89 g, 11.55 to 19.88) and kept them in captivity until parturition. Mean litter size and litter mass were 6.2 ± 1.3 (5 to 8 neonates) and 3.85 ± 0.88 g (2.99 to 5.13 g), respectively. Mean neonatal size and mass were 81.2 ± 4.1 mm (total length = 70 to 90 mm, N = 26) and 0.62 ± 0.07 g (0.49 to 0.82 g, N = 31), respectively. On average, the relative litter mass represented 32 ± 3% (29% to 36%) of the postpartum female body mass. The estimated mass of water lost at birth (total mass loss at parturition minus litter mass) was 0.37 ± 0.39 g (0.00 to 0.98 g), representing 10 ± 8% (0 to 26%) of the individual neonate mass. This low value is in line with that expected for viviparous squamates from arid climates, which is much lower than that observed in oviparous or in viviparous squamates from temperate climates. These results help to fill a gap, as the reproductive output of Chalcides striatus has been poorly documented, but mostly because the importance of extraembryonic water mass has been neglected.

Are Bergmann's and Jordan's rules valid for a neotropical pitviper?

AbstractMorphological variation along the spatial distribution of species has been extensively investigated in ecological studies, and several ecogeographical rules explore the relationships between morphological traits and the environment. Many morphological traits are correlated, providing an opportunity to evaluate the validity of multiple ecogeographical rules simultaneously. Bergmann's rule predicts that endothermic animals in colder locations are larger than those in warmer locations. Jordan's rule predicts that fish from colder locations have more vertebrae than those from warmer locations. We tested the validity of Bergmann's and Jordan's rules for the neotropical lancehead snake Bothrops jararaca. We evaluated three morphological characters of 342 specimens: number of ventral scales (proxy for vertebrae number), snout–vent length (a linear measure of body size) and stoutness (volumetric body size). We implemented spatial regressions to evaluate the variation of morphological dimensions using climatic predictors: the minimum temperature and evapotranspiration. SVL was poorly related to minimum temperature and evapotranspiration. However, stouter individuals were found in colder places with greater evapotranspiration, following Bergmann's rule and the water conservation hypothesis. Individuals in warmer locations also had a greater number of ventral scales, reversing Jordan's rule. We showed that different selective pressures act on different morphological dimensions. Although stoutness follows Bergmann's rule, its variation would arise from an energy storage demand rather than heat conservation. Also, stoutness variation along evapotranspiration gradients could represent a mechanism to avoid hydric stress in environments with considerable climatic variations. The variation in vertebrae number along temperature gradients could be related to ecological factors and foraging. We highlight that physioecological mechanisms to deal with climatic variation and ecological aspects could be identified in snakes through intraspecific analyses, contrasting with interspecific studies that can hardly detect general trends. Due to different environmental effects on body size, we shed new light on the importance of exploring multiple morphological dimensions in macroecological studies.

Description of a new sandstone-dwelling species of genus Cnemaspis (Sauria: Gekkonidae) from Gunung Santubong National Park, southwestern Sarawak, Malaysia

A newly discovered sandstone-dwelling species of the rock gecko, genus Cnemaspis, is described from Santubong National Park, 25 km north of Kuching, southwestern Sarawak, Malaysian Borneo. Molecular phylogenetic analysis confirmed that Cnemaspis puterisantubongae sp. nov. is closely related to other Cnemaspis species in southwestern Sarawak, except for C. kendallii, although these relationships remain unclear. The new species differs from closely related species in having a moderate snout–vent length of up to 66.7 mm; 10–14 precloacal pores in males; 9–14 obviously-convex precloacal pore-bearing scales in females; enlarged, smooth, flat median subcaudal scales; sharp-edged, broad black markings on the trunk dorsum; and a black–gray banding pattern on the posterior part of the original tail, with white median subcaudal scales in males. This discovery of this new species from Santubong National Park, which is highly accessible due to its proximity to Kuching, highlights the need for extensive inventory surveys throughout the national parks of Sarawak.

Analysis of Morphological Change during a Co-invading Assemblage of Lizards in the Hawaiian Islands

Phenotypic change plays diverse roles in species’ colonization, but most invasion studies target single species. To compare ecomorphological changes among co-invading species with overlapping niches, we examined three lizards on the island of O‘ahu (Anolis carolinensis, A. sagrei, Phelsuma laticauda). Using specimens from three decades of unfolding invasions obtained through museum collections and contemporary field work, we quantified shifts in three traits: snout vent length (SVL), forelimb-, and hindlimb-length (limb lengths relative to SVL). We hypothesized that competition among these three species has led to ecological shifts that will be detectable through morphological change. Overall, we found that unique patterns of phenotypic change were both species-specific and sex-specific within species: (1) male A. sagrei, female A. carolinensis, and male P. laticauda increased in SVL and (2) relative hindlimb length increased in female A. carolinensis since the 1980s. The observed changes involve traits that may be consequential to invasion dynamics. This study illustrates how museum- and field-based research can be integrated to document nuanced temporal patterns in the phenotypes of co-invading species that share similar niches in native ranges, raising questions about the underlying process(es) driving species- and sex-specific change in co-invaded systems.

Life-history of masked water snakes (Homalopsis buccata) in Java: implications for the sustainability of harvesting

Context Masked water snakes (Homalopsis buccata, Homalopsidae) thrive in the muddy edges of agricultural ponds and canals in densely populated areas of West Java, Indonesia, and are harvested by local farmers to protect fish stocks and to provide meat, skins, and medicines for commercial use. Aims Here, we aimed to quantify sexual dimorphism and reproductive biology of H. buccata, so as to deepen our knowledge of the species’ inherent ability to withstand commercial harvests. Methods We examined carcasses of 4286 snakes at six processing sites to quantify biological attributes (e.g. sexual dimorphism in body size and shape, seasonality of reproduction, fecundity, reproductive frequency), with emphasis on traits that affect the ability of snake populations to withstand this intensive harvesting. Key results The snakes we examined were primarily adults (<1% juvenile), with approximately equal numbers of males and females except in January (when females comprised >90% of specimens). Females grow larger than males, and they are more heavy-bodied but shorter-tailed than are males of the same snout–vent length. Reproduction is seasonal in both sexes, with testis volumes decreasing to a minimum over the period August to November (late dry season) when most adult-size females were gravid. Litter sizes ranged from 1 to 37 (mean 12), increasing with maternal body size, with ~75% of females reproducing each year. Conclusions On the basis of these results, we infer that the life history of H. buccata (viviparity, high fecundity, frequent reproduction, rapid maturation) renders it inherently resilient to harvesting, especially because that offtake is based on males as well as females. Because a lack of sustainability is evident only in hindsight, regular monitoring of the trade could assure that any problems are detected rapidly. Implications To further buffer these populations from the impact of harvest, hunting could be restricted during January (a time when gravid females are disproportionately vulnerable) and the largest snakes (females, with high fecundity and reproductive frequency) could be excluded from harvests.

Diet composition of three amphisbaenian species (Amphisbaena alba, Amphisbaena pretrei, and Amphisbaena vermicularis) from Northeast Brazil

Amphisbaenians usually have a diet composed of a wide variety of small arthropods, with some species being more selective in their feeding and others considered more generalist. Using only specimens deposited in scientific collections, the diet composition of Amphisbaena alba Linnaeus, 1758, Amphisbaena pretrei Duméril and Bibron, 1839, and Amphisbaena vermicularis Wagler, 1824 from the Northeast region of Brazil was analyzed. Except for individuals of A. alba, due to the small sample size, we also investigated the possible intersexual difference in the volume, length, and number of prey in the diet of amphisbaenians and the possible relationship between prey volume and body size (snout–vent length) of individuals was analyzed. The diet of worm-lizard in general was composed of termites, cockroaches, ants, and beetle larvae, and no intersexual differences were found in the size, length, and number of consumed prey. The body size of A. pretrei and A. vermicularis showed no relationship with the volume of prey consumed. Amphisbaenians presented a characteristic diet of opportunistic generalist predators, with several food categories in the composition of their diets, indicating that the studied species feed according to the availability and abundance of prey in the environment.

Digestive tract morphology and argyrophil cell distribution of three sympatric lizard species

The digestive tract plays a crucial role in an organism’s health. Here, the digestive tract morphology and argyrophil cell distribution of three sympatric lizard species, Teratoscincus roborowskii, Phrynocephalus axillaris and Eremias roborowskii, were studied. Our results show that T. roborowskii’s snout–vent length (SVL) and digestive tract length (DTL) were significantly longer than those of P. axillaris and E. roborowskii. P. axillaris’ relative intestine length was 1.25, which was significantly longer than those of the other two species. The three lizard species’ digestive tract structures were generally similar, whereas their histologic characteristics exhibited significant differences. Particularly, T. roborowskii’s and P. axillaris’ esophagus mucosa was pseudostratified ciliated columnar epithelium, whereas simple columnar epithelium was observed in E. roborowskii, which also had fewer mucosal folds than the other two species. In all three lizard species, the small intestines’ mucosal lining consisted of simple columnar epithelium with many goblet cells; the largest quantity of villi was found in T. roborowskii. Moreover, T. roborowskii’s mucous membrane (MM) and tunica muscularis (TM) were obviously thicker than those of the other two species. However, the argyrophil cells’ distribution densities of the three species were remarkably different; such differences were highest in the cardia of T. roborowskii and E. roborowskii, but P. axillaris was observed to have more argyrophil cells in its stomach body. Our results indicated that the three lizards’ different histomorphologies might be due to limited food resources, availability of a single food type in the Turpan Basin’s extremely arid and hot environment, as well as T. roborowskii’s special frugivorous behavior. Morphological studies of these lizards are necessary to understand their digestive systems’ structure and operation, as well as to facilitate physiological studies of adaptions to extreme desert habitats.

Determining the generation length and level of morphological and genetic differentiation in the Data Deficient glossy grass skink (Pseudemoia rawlinsoni)

Context Human activities are having a significant impact on biodiversity worldwide, to the extent that we are in the midst of the sixth mass extinction event. Although a substantial proportion of species globally have an elevated risk of extinction, some species are poorly known and there is insufficient information available to adequately assess their risk of extinction. Aims and methods One such species is the glossy grass skink (Pseudemoia rawlinsoni), a widespread but enigmatic lizard species in south-eastern Australia. In order to improve our knowledge of its life history, and particularly its generation length, we examined museum specimens collected from across the range of the species, supplemented with measurements from field-caught individuals. Key results We estimated that the species reaches sexual maturity in 3 years, at approximately 40 mm snout–vent length. Its generation length was estimated as 5 years. Sexual dimorphism was evident, and female body size was positively related to litter size. Although there was no evidence for substantial variation in morphology across the range of the glossy grass skink, a phylogeographic analysis using mitochondrial DNA sequence data (ND4) revealed the presence of seven genetic sublineages (up to 5.1% genetic divergence) within the species. Conclusions The glossy grass skink appears to be a single, but widespread and genetically variable, species. Implications Our study demonstrates how a targeted, multifaceted study can be effective at rapidly gathering data that can be used to contribute vital information to the assessment of extinction risk in Data Deficient species.

A chance encounter in central Texas yields insights on the ecology of aestivating Siren nettingi (Caudata: Sirenidae)


 
 
 
 Siren spp. are often dominant vertebrates in the wetlands they occupy and are known to estivate when such wetlands dry up. Practical considerationslimit in-situ observations of estivating individuals. On 12 October 2021, we incidentally discovered an estivating aggregate of Siren nettingi in Bastrop County, Texas, USA. These salamanders were excavated from compact, rocky soil adjacent to a caliche road, at depths that ranged between ~0.2 to 1.5 m. The dominant vegetation at this site included Ulmus crassifolia, Persicaria sp., and various grass species. We recovered 140 individuals of which seven were salvaged and 133 were captured live. We measured 115 of these for snout–vent length (SVL) and observed the aggregate was predominated by juveniles. We estimated an estivation density of 2.33 sirens/m2 that is comparable to densities estimated for non-estivating populations. However, in-lieu of monitoring that was in place for this study, we expect a mass mortality event would have likely occurred. We therefore suggest that roadway construction in preferred habitat be considered as a threat to siren populations.
 
 
 

Hemoparasites Do Not Affect Life-History Traits and Cellular Immune Response in Treefrog Hosts Boana cordobae.

We provide the first evidence for hemoparasites in the endemic Cordoba treefrog Boana cordobae. We collected 37 adult frogs at 1200 m a.s.l. in the Comechingones Mountains in the Córdoba province (Argentina). Each individual was sexed, then snout-vent length and body mass were recorded, a toe was collected for skeletochronological age determination, and a slide with a blood smear was prepared for hemoparasite screening, before releasing the frogs in situ. A total of 81% (n = 30) of the frogs were infected by hemogregarines and trypanosomes with a high intensity of infections. Dactylosoma was found for the first time in Argentina. Hemoparasites had no significant effect on the leukocyte profile, which we assessed from the May-Grünwald-Giemsa-stained blood smears. The neutrophils/lymphocytes ratio, indicative of stress, was insignificantly higher (0.06) in parasitized frogs than in parasite-free individuals (0.04). Infected frogs were larger than the controls, but this effect vanished when correcting size data for age. Young frogs (first-breeders) dominated the age distribution of parasite-free individuals, suggesting that infection of frogs takes usually place after sexual maturation. Vectors transmitting hemoparasites to B. cordobae remain to be identified. We demonstrate that moderate to high intensities of hemoparasites do not significantly affect the cellular immune response of B. cordobae, or any of the life-history traits studied, nor did they show any external sign of disease.

Scaling relationships of maximal gape and prey size of snakes for an egg‐eating specialist (Dasypeltis gansi) and a dietary generalist (Pantherophis obsoletus)

AbstractThe size of both predators and prey can profoundly affect the foraging ecology of animals. This is especially true for snakes which consume prey whole. Although their gape imposes an anatomical limit on prey size, different snake species have a wide variety of prey types, prey sizes, and dietary breadth. To test whether a dietary specialist that only consumes bird eggs (Dasypeltis gansi) differed from a generalist that occasionally eats eggs (Pantherophis obsoletus), I quantified and compared the scaling relationships between overall size, cranial dimensions, and maximal gape and the orientation and mobility of relevant bones. Compared to P. obsoletus with a given overall size, D. gansi had maximal gape areas approximately 3–4 times greater and a significantly larger relative contribution to gape by the intermandibular (IM) soft tissues (50% vs. 19%). The greater distensibility of the IM soft tissues also allowed much greater lateral displacement of the distal end of the lower jaw in D. gansi versus P. obsoletus, but at maximal gape, the bones of these species had unexpectedly similar orientations in lateral view. The large gape of D. gansi was attained despite having a significantly shorter head than P obsoletus for a given snout–vent length. As a result of their large gape and more slender build, the predicted values of relative prey masses (RPM) for D. gansi at maximal gape vastly exceeded those of P. obsoletus for a given prey type. Although eggs are much stouter than rats, values of RPM at maximal gape for D. gansi eating eggs greatly exceeded those for P. obsoletus eating rats. Perhaps, Dasypeltis has the greatest size‐corrected gape and potential values of RPM (for a given prey shape) of any snake taxon as these values of D. gansi exceed those from all previously studied species with similar data.

Doğu Akdeniz, Türkiye'deki Su Kurbağalarının (Pelophylax ridibundus-complex) Üreme Ekolojisi ve Larval Gelişimi

Reproductive biology of Marsh frogs (Pelophylax ridibundus s.l.) was investigated in the Eastern Mediterranean Region of Türkiye in terms of reproductive phenology, fecundity, clutch size, reproductive effort, and mate choice. Frogs are active for approximately ten months throughout the year and hibernate between November and January. Breeding occurs from mid-January until early June and metamorphosis took 45-65 days, with juveniles observed from the end of March. The tadpole reaches its largest size at stage 38, with a mean total length of 60.61 mm and juveniles have an average snout-vent length of 20 mm at the end of metamorphosis. Secondary sexual characters can be observed on individuals reaching 45 mm snout-vent length and we could not detect any amplexed pairs below this length. The clutch size of spawned egg masses ranged between 144 – 645 and the mean egg size was calculated as 1.73 mm. The mean fecundity was 3853 (ranging between 940 and 6000) eggs and the reproductive effort was 0.094 in females. Females were approximately 16% larger than males and the snout–vent length of males and females of amplexed pairs is significantly different but not correlated. These findings signify random mating instead of size-assortative mating. However, the preference of 6.8% larger females than single ones to mate indicates a size-dependent mating for Western Mediterranean population.

“Anteaters” under the airport: a slender new species of blindsnake, genus Indotyphlops, from Timor-Leste (Scolecophidia: Typhlopidae: Asiatyphlopinae)

We describe a slender immature female blindsnake from the main airport in Dili, Timor-Leste, as a new species of Indotyphlops, adding a third species to the country's known blindsnake fauna of Sundatyphlops polygrammicus (Schlegel, 1839) and Virgotyphlops braminus (Daudin, 1803). The new species has the following combination of characteristics: small size (snout–vent length = 119 mm), slender body (relative body thickness 71), T-V supralabial imbrication pattern, relative rostral width 0.36, 434 middorsal scales, relative tail length 1.7%, absence of enlarged occipital scales, and apical spine absent. The snake was found in an ant nest under several flat rocks near the fuel depot of Nicolau Lobato International Airport, and this habitat and the discovery in a busy location with heavy human impacts indicate that the species is likely a primarily subterranean myrmeco- or termitophage.

Morphometrics, Habitat and Breeding Activity of Asian Common Toad, <i>Duttaphrynus melanostictus</i>, in Pakistan

The scientific data on ecology of amphibians from Pakistan are scarce. Asian Common Toad (Duttaphrynus melanostictus) is widely distributed in South Asia, and has been introduced outside its range causing severe ecological problems. We gathered data on morphometrics, habitat and breeding activity of the species in its western edge, North Punjab, Pakistan, of the range. The morphometric measurements of Asian Common Toad showed that the males were 49 ± 3.4 mm in snout vent length while the females were 58 ± 5.5 mm. Of the 13 measurements tested, the factor analysis produced five (head width, forelimb length, femur length, width of upper eyelid and foot length) significant measurements (r 0.80) for male while six (snout-vent length, head width, head length, greatest tympanum diameter, forelimb length, length of tarsus and foot) for female. The substrate of the habitat of Asian Common Toad was recorded as muddy to stony; water with neutral to slightly alkaline pH; dominated by herbs: Cannabis sativa, Parthenium hysterophorus; shrubs: Dodonaea viscosa, Lantana camara; grasses: Cynodon dactylon, Dactyloctenium aegyptium; and hydrophytes Alternanthera sessilis and Centella asiatica. The mean air and water temperature (day) during the breeding period were 27 – 30.5 and 25 – 28.5°C, respectively. The toad species laid eggs in small sized pools with lentic to slow-moving water with the mean depth of 32 – 64 cm. The males were more abundant than females (2.14♂:1♀) at the breeding sites. The advertisement call was of 9.3 ± 0.80 sec duration with a single note and 49.5 ± 6.5 nodes, –7.45 ± 0.95 average amplitude, 776 ± 51.8 Hz minimum frequency and 7011 ± 1680 Hz maximum frequency.

MACGRAN-IJ: AN EFFICIENT METHOD TO ANALYZE DIMENSIONS AND COLOR OF WHEAT GRAINS

The dimensions, shape, and color of wheat grain are important in plant breeding, although their manual measurement is difficult and time-consuming. While it is true that digital image analysis (DIA) with specific software has made it easier, some are semiautomatic, exclude color, and require the digitization of individual grains. The goal of this study was to compare the precision, accuracy, and efficiency of MacGran-IJ versus SmartGrain, GrainScan, and manual caliper measurement. The morphological characteristics of durum wheat (Triticum durum Desf.) and bread wheat (Triticum aestivum L.) grains were measured using DIA with MacGran-IJ, including color (in RGB and CIELab color spaces), size (mm2), lateral length (LLG, mm), ventral length (VLG, mm), lateral (LWG, mm) and ventral (VWG, mm) width, perimeter (mm), and circularity. Length, LWG, and VWG were measured with a digital caliper. The time (s) taken in each method was recorded. Size, LLG, VLG, and VWG were the same between methods for both species, but the LWG measurement obtained with vernier showed differences between the three programs (p ≤ 0.01), as well as low accuracy and precision. VWG obtained manually had R2 values of 0.92, 0.91, and 0.89 (p ≤ 0.01) for MacGran-IJ, SmartGrain, and GrainScan, respectively. The ventral and lateral color red of wheat grain differed between MacGran-IJ and GrainScan; the lateral part of the bread wheat grain showed differences for red, green, and blue (p ≤ 0.05). DIA in CIELab color required 11.57 s, and in RGB it needed 7.25 s (p ≤ 0.01). Manual measurement of 50 wheat grains required 1528.07 s, whereas SmartGrain took 101.84 s, MacGran-IJ 45.4 s, and GrainScan 54.11 s (H = 36.59, p ≤ 0.01). MacGran-IJ is an automated, simple, and efficient method for accurately measuring the size, length, and width of wheat grains using digitized images

Variation in body size and reproductive characteristics among chromosomal races of the Sceloporus grammicus complex in México

Abstract Populations and chromosomal races of a species often show variation in life-history characteristics due to phylogeny and environmental factors. We analysed variation in snout–vent length (SVL) and reproductive variables, such as minimum SVL at sexual maturity, litter size and embryo volume in females of the Sceloporus grammicus lizard complex, which includes seven chromosomal races as well as hybrid zones among different combinations of races (F5, F5 + 6, potential but unverified F5 + 6, F6, FM1, FM2, FM2 × F5 hybrid zone, FM3, LS and unverified SGG). The SGG, F5 and LS females were larger than F6 and FM3 females. Females with non-vitellogenic follicles and vitellogenic follicles were smaller than females with embryos. The SVL of females containing embryos varied among chromosomal races, the largest being the same as indicated above, but the smallest was the FM2 × F5 hybrid zone. Litter size was similar among chromosomal races (5.8 embryos), while embryo volumes varied among them. Two patterns of reproductive activity were found: seasonal and continuous reproduction. Our results showed the influence of environmental factors of each locality, which supports the ecological hypothesis. The use of chromosomal races did not reveal a significant phylogenetic effect, because allozyme and molecular data show only small pairwise genetic distances among the S. grammicus populations on the Mexican Plateau.

Effects of environmental factors on the ecology and survival of a widespread, endemic Cerrado frog

AbstractUnderstanding the mechanisms that affect habitat use by vertebrates is critical for understanding how species are distributed across landscapes and how they cope with habitat change. The Brazilian Savanna (the Cerrado) has vegetation ranging from grassland to woodland savannas and harbors a rich and diverse amphibian fauna impacted by accelerated habitat loss. Here, we test the influence of vegetation type (from grassy scrubland to woodland) and distance from breeding sites (ephemeral water bodies) on body size, abundance, and survival of the frog Physalaemus nattereri in a natural metapopulation system of south‐central Brazil. We also test whether body size is a significant predictor of population abundance. We found that the abundance of P. nattereri varies according to the mean snout–vent length of each metapopulation (sampling unit), as well as a higher estimated mortality rate in woodlands compared with typical Cerrado. Furthermore, we found no difference in estimated mortality among sampling units located far or close to ephemeral water bodies. Thus, our results highlight variable responses of P. nattereri metapopulations to environmental factors, despite the observed high heterogeneity among sampled habitats and the importance of ephemeral water bodies for reproduction. These findings highlight that land cover and availability of breeding sites might not always interact to explain population persistence of Cerrado frogs.