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In this study, we investigated the mechanisms used by the arboreal termite Nasutitermes corniger (Motschulsky, 1855) to follow trails from the nest to sources of food. A plate containing one of seven trail types was used to connect an artificial nest of N. corniger with an artificial foraging arena. The trail types were: termite trail; paraffined termite trail; trail made of paraffin; rectal fluid extract trail; sternal gland extract trail; feces extract trail; and solvent trail (control). In each test, the time was recorded from the start of the test until the occurrence of trail following, at which point the number of termites that followed the trail for least 5 cm in the first 3 min of observation was recorded. The delay for termites initiating trail following along the termite trail was lower (0.55 ± 0.16 min) than in the trails of sternal gland extract (1.05 ± 0.08 min) and trails of termite feces extract (1.57 ± 0.21 min) (F2, 48 = 22.59, P < 0.001). The number of termites that followed the termite trail was greater (207.3 ± 17.3) than the number that followed the trail of termite feces extract (102.5 ± 9.4) or sternal gland extract (36, 9 ± 1.6) (F2, 48 = 174.34, P < 0.001). Therefore, feces on the trail may play an important role alongside sternal gland pheromones in increasing the persistence of the trail.
Urodele amphibians can regenerate their limbs after amputation. After amputation, undifferentiated cells appear on the amputation plane and form regeneration blastema. A limb blastema recreates a complete replica of the original limb. It is well known that disturbance of the location of limb tissues prior to amputation perturbs limb patterning, suggesting that different intact limb tissues carry different location information despite their identical appearance. The cause of such differences in intact tissues remains unknown. In this study, we found that Lmx1b, Tbx2, and Tbx3 genes, which are expressed in developing limb in a region specific manner, remained detectable in a mature axolotl limb. Furthermore, those position-specific gene expression patterns were conserved in mature limbs. Treatment with retinoic acid (RA), which is known to have ventralizing activity, changed Lmx1b expression in intact dorsal skin and dorsal character to ventral, indicating that conserved Lmx1b expression was due to the dorsal character and not leaky gene expression. Furthermore, we found that such conserved gene expression was rewritable in regeneration blastemas. These results suggest that axolotl limb cells can recognize their locations and maintain limbness via conserved expression profiles of developmental genes.
Parthenogenesis is a form of clonal reproduction. Eggs develop in the absence of sperm and offspring are genetically identical to their mother. Although common in invertebrates, it occurs in only a few species of squamate reptiles. Parthenogenetic reptiles have their origin in interspecific hybridization, and their populations are exclusively female. Because of its high mutation rate and maternal inheritance, mitochondrial DNA sequence data can evaluate the origin and evolution of all-female vertebrates. Partial sequences from two mitochondrial genes, Cytb and ND4, were analyzed to investigate questions about the origin of parthenogenesis in the Aspidoscelis cozumela complex, which includes A. cozumela, A. maslini and A. rodecki. Low levels of divergence were detected among parthenogenetic species, and between them and A. angusticeps, confirming it as the maternal species of the parthenoforms. A gene tree was constructed using sequences from three populations of A. angusticeps and nine of its unisexual daughter species. The phylogeny suggests that two independent hybridization events between A. angusticeps and A. deppii formed three unisexual species. One hybridization resulted in A. rodecki and the other formed A. maslini and A. cozumela. Although A. cozumela has the haplotype characteristic of A. maslini from Puerto Morelos, it is considered to be a different species based on karyological and morphological characteristics and its geographical isolation.
Human and livestock related disturbances of habitat selection by ungulates are topics of global concern, as they have profound impacts on ungulate survival, population density, fitness, and management; however, differences in ungulate habitat use under different human and livestock densities are not fully understood. Mongolian gazelle (Procapra gutturosa), an endemic ungulate species on the Asia-European steppe, faces varying intensities of human and livestock disturbances in the area around Dalai Lake, China. To investigate how habitat selection strategies vary as disturbance intensity changes, we randomly set 20 transects containing 1486 plots, on which we conducted repeated surveys of 21 ecological factors during the winters in the period of 2005–2008. We aimed to: 1) determine the critical factors underlying habitat selection of the gazelles; 2) determine the gazelles' habitat preferences in this area; 3) determine how habitat selection varies with disturbance intensity and explore the primary underlying mechanism. We used binary-logistic regressions and information theoretic approaches to build best-fit habitat selection models, and calculated resource selection functions. Sixty-six herds, 522 individuals, and 499 tracks were recorded. Our results indicate that snow depth and aboveground biomass are the main factors affecting habitat selection by Mongolian gazelle throughout the district in winter. Thin snow cover and abundant aboveground biomass are preferred. Avoiding disturbance was the primary factor accounting for habitat selection in low disturbance areas, although with increasing human or live-stock-related disturbance, gazelle maintained a reduced distance to the source of the disturbance. Presumably owing to that shift, movement costs were more important as disturbance increased. In addition, Mongolian gazelle selected habitats based on topographical features promoting greater visibility where disturbance was lower. We suggest several management implications of our findings for this ungulate species will contribute to the effective conservation of Mongolian gazelle in the Dalai Lake area.
Assessment of salivary volatile compounds adopting gas chromatography-linked mass spectrometry (GC-MS) analysis revealed the presence of a total of 11 compounds in the buffalo saliva irrespective of the stages in the reproductive cycle. p-cresol was identified as an estrus-specific volatile compound in the saliva. In addition, modeling of odorant-binding protein (OBP) and β-lactoglobulin revealed that OBP is highly stable and has strong binding affinity with p-cresol. Hydrogen bond interactions indicated that OBP is responsible for pheromone release through saliva. In contrast, β-lactoglobulin, which belongs to the same lipocalin family as OBP, possesses less affinity to p-cresol than OBP, suggesting that it is not involved in p-cresol binding and transport. Phylogenetic characterization revealed that bovine family of OBP is separately clustered. It is suggested that p-cresol has the potential to be developed as a biomarker to detect the reproductive status in the buffalo and for behavioral manipulations.
I examined the reproductive strategies of leopard toad and mascarene frog by studying their annual vitellogenic cycle, monthly changes of masses of ovary, liver and fat bodies as well as egg size and number in two study areas, Abo Roash and El Mansuriya, and in the years 2001, 2005, and 2008–2009, particularly during the final two years of that period. Based on the presence of the mature ova, I found that vitellogenic cycle is continuous in toad, but discontinuous in frog. Further, leopard body reserves allocated more energy to vitellogenesis than did mascarene frog. Hence, fecundity in toad was higher than that in frog, as associated with higher egg number and size. During oviposition, female mascarene retained a small portion of a clutch, whereas toad shed all egg mass at once. Over the study period, both body and reproductive conditions reacted positively in toad, but negatively in frog. Warm temperature and long photoperiod elucidated ovarian development under high relative humidity in frog. In contrast, in toad, low relative humidity may be an environmental cue for the increase in ovarian mass. Thus, higher sexual activities occurred in spring for toad (dry environment), but in moist summer for frog. Ovarian mass and egg number were temperature-dependent in frog, but independent in toad. Relative humidity correlated significantly and negatively to egg size in both populations. It also related inversely to egg number in toad, but not in frog. Hence, eggs of the frog are controlled by both temperature and humidity in summer season. Rainfall had no effect on sexual parameters in both species.
We record a tree frog of the genus Chiromantis for the first time from outside the Southeast Asian continent and describe it as a new species, Chiromantisinexpectatus. The new species from the Malaysian state of Sabah, Borneo, is a small-sized Chiromantis (male snout-vent length ca. 22 mm), and is distinguished from all other members of the genus by the combination of the following morphological characteristics: dark stripes absent, but dark spots present on dorsum; a dark-brown lateral band present from snout tip to half of body, bordered ventrally by white stripe; third and fourth fingers less than half webbed; third finger disk wider than tympanum diameter; and inner metatarsal tubercle present. Significance of findings of this species from Borneo Island, as well as phylogeny and breeding habit of the genus Chiromantis, are briefly discussed.
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