Implications of assumption violation in density estimates of antelope from dung-heap counts: a case study on grey duiker (Sylvicapra grimmia) in Zimbabwe

Dung‐heap counts were used to estimate density of grey duiker (Sylvicapra grimmia Linnaeus 1758) in the Matobo National Park, Zimbabwe. To test assumptions of this method, defecation rate and defecation site selection were investigated under captive and field conditions, and densities were compared with independent estimates derived from territory mapping. Many assumptions were violated: males defecated more frequently than females with mean dry mass per deposit greater in females, but total daily faecal production was similar between sexes. Spatial distribution of faeces was clumped, and 52.8% of locations contained multiple deposits. Duikers exhibited habitat type preferences (i.e. low‐ to medium‐density woodland) with herbaceous layer heights 40–100 cm and visibility >20 m. Calculated grey duiker density from dung‐heap counts in cleared plots was 9.7 ± 1.3 animals km⁻², approximately double the territory‐mapping estimate based on Minimum Convex Polygons (5.13 animals km⁻²) but similar to the 75% Fixed Kernel estimate (10.95 animals km⁻²). Provided that sex ratios approach parity and sampled area is representative of all utilized habitats, violation of basic assumptions of the dung‐heap count method has a minor effect on density estimate accuracy.     

Age determination and growth in the hyrax Procavia capensis (Mammalia: Procaviidae)

The use of eye lens weight, tooth eruption and tooth attrition has been investigated as a method for age determination in the hyrax. Illustrations are presented on the stages of eruption to reduce subjectivity of eruption criteria and to aid age determination. All teeth are fully erupted and in wear by five years of age, from which point age determination can be based on attrition of M3. Growth with age is described by means of the von Bertalanffy equation. Asymptotic weight is reached by 60 months, asymptotic body length and body girth by 40 months, and hindfoot length by 35 months. The asymptotes and the coefficient of catabolism (K) are compared with values obtained in other studies.     

Age determination, age structure, and longevity in the mole Scalopus aquaticus (Mammalia: Insectivora)

Three hundred and eighty-two moles, Scalopus aquaticus , were collected from 16 sampling grids located within a 23 km² area in South Carolina, USA. Age of moles was determined using tooth wear. Both the mean and median ages of trapped moles were c. two years; the oldest mole was in its seventh year of life. More than 50% of the individuals are estimated to die during the first six months of life; adult survivorship was relatively high and age-dependent. There was differential mortality between the sexes, and females lived longer than males. Scalopus aquaticus in South Carolina lived c. 1.2 times longer than the maximum lifespan predicted on the basis of body mass. Pooled samples of moles yielded the expected age distribution, with fewer individuals occurring in successively older age classes. However, based on bootstrap estimates of the variance in age structure, samples from some grids contained significantly more young or old individuals than expected due to sampling error. Mole populations appear not to be in demographic equilibrium at this local scale, but instead conform more closely to a metapopulation-type of structure.     

Foraging and habitat use of common duikers,Sylvicapra grimmia,in a heterogeneous environment within the Soutpansberg,South Africa

We investigated aspects of the foraging behaviour and activity patterns of free‐ranging common duikers (Sylvicapra grimmia) within the Soutpansberg, South Africa. We used giving‐up densities (GUD) and camera traps to test for habitat selection and patch‐use behaviour by common duikers inhabiting a grassland containing distinct ‘islands' of woody vegetation. Foraging in or around a wooded island was affected by its surrounding vegetation. GUDs were significantly lower in portions dominated by tall grass and scattered ferns and highest in areas with open short grass and thick fern. Using grids of 5 × 5 stations, we mapped the duikers' foraging on a larger scale that incorporated neighbouring rocky hillsides. The duikers preferred feeding in areas with tall grass and scattered fern (sufficient cover and escape routes), followed by the wooded islands and thick fern (lack of sightlines/escape routes and presence of predator‐ambush sites), whereas little foraging occurred at the edges and rocky areas (hard substrate that impede escape potential). Photos (total 873) revealed solitary activity, highest in the late afternoon. Photos of vigilant individuals were mostly from rocky and fern habitats. Our results suggest that the duikers allocated their feeding efforts, activity and vigilance patterns to attune to their perceived risk of predation within their heterogeneous environment.     

Age determination and growth rate of eels, Anguilla anguilla (L)

Measurements taken from a series of photographs of otoliths of 37 eels caught in a stretch of river of 150m length were used to prepare a growth curve based on back-calculated measurements. Values of L ∞= 1045 and K = 0.046 were determined. Mean incremental growth calculated as 33 mm per year agreed closely with increments determined from growth observed up to 4 years after tagging eels from the same location. Inconsistencies in results of age determinations based on burned otoliths are described but it is concluded that the technique yields results of sufficient reliability to be used in practical management situations.     

Cope's rule and the evolution of body size in Pinnipedimorpha (Mammalia: Carnivora)

Cope's rule describes the evolutionary trend for animal lineages to increase in body size over time. In this study, we tested the validity of Cope's rule for a marine mammal clade, the Pinnipedimorpha, which includes the extinct Desmatophocidae, and extant Phocidae (earless seals), Otariidae (fur seals and sea lions), and Odobenidae (walruses). We tested for the presence of Cope's rule by compiling a large dataset of body size data for extant and fossil pinnipeds and then examined how body size evolved through time. We found that there was a positive relationship between geologic age and body size. However, this trend is the result of differences between early assemblages of small-bodied pinnipeds (Oligocene to early Miocene) and later assemblages (middle Miocene to Pliocene) for which species exhibited greater size diversity. No significant differences were found between the number of increases or decreases in body size within Pinnipedimorpha or within specific pinniped clades. This suggests that the pinniped body size increase was driven by passive diversification into vacant niche space, with the common ancestor of Pinnipedimorpha occurring near the minimum adult body size possible for a marine mammal. Based upon the above results, the evolutionary history of pinnipeds does not follow Cope's rule.     

Funktionsanatomische untersuchungen an der kaumuskulatur des blauduckers Cephalophus monticola (Thunberg, 1789) (Mammalia,Bovidae) Investigations on the gross functional anatomy of the muscles of mastication in the blue duiker,Cephalophus monticola (Thunberg, 1789) (Mammalia,Bovidae)

The study of the masticating muscles of ruminants has been rather neglected. Two specimens (skinned head and skull) allowed for the study of the shape of the masticating muscles and their tendinous skeleton. The masseter conformed fairly well to the normal bovid type, the other three muscles very much less so. The outer ear has a special supporting osseous process.     

Age determination, bomb-radiocarbon validation and growth of Atlantic halibut (Hippoglossus hippoglossus) from the Northwest Atlantic

Atlantic halibut (Hippoglossus hippoglossus) is the largest and one of the most widely-ranging and commercially-valuable groundfish in the Atlantic Ocean. Although presumed to be long-lived, their age and growth has not been validated. Ages were estimated by counting growth increments from approximately 2400 thin-sectioned sagittal otoliths collected from the Scotian Shelf and southern Grand Banks off eastern Canada. The accuracy of age estimates made from otolith thin sections was validated using bomb-radiocarbon assays of 13 otolith cores whose year of formation ranged from 1949 to 1975, encompassing the timeframe of the global radiocarbon pulse. Known-age juvenile halibut from a culture facility were used to identify the approximate location of the first annulus. Growth rate for males and females was similar up to about 70 cm (~5 years), after which point male growth slowed, while female growth continued to an age of up to 38 years and a maximum observed size of 232 cm. Males grew to an observed maximum length of about 175 cm and a maximum age of 50 years. A comparison of age estimates for otoliths collected in a ‘historic’ time frame (1963 to 1974) with those from recent years (1997 to 2007) shows that growth rate has not changed appreciably between the two time periods. Small but significant growth differences were observed between the Scotian Shelf and southern Grand Banks for both sexes, while large differences in length at age were observed between halibut caught with longline compared to otter trawl due to differences in length-based gear selectivity. Age interpretations based on sectioned otoliths tended to be 10–15% different than those based on break and burn, although the age comparison was confounded by other variables and must be considered provisional. Atlantic halibut is a long-lived fish, living up to at least 50 years, an important consideration for the management of the fishery.     

Age and annual growth rate cause spatial variation in body size in Phrynocephalus przewalskii (Agamid)

Whether or not biogeographic rules dealing with spatial patterns of animal body sizes are valid for ectotherms is controversial. As the ectotherms grow all their lives, we explored the role of age and annual growth rate in body size variation in Phrynocephalus przewalskii in northern China. Morphological data were collected from 11 populations across a broad geographic gradient. Correlations between age, sex, climatic factors, and body size were analyzed using generalized linear model (GLM) and generalized linear mixed model (GLMM). GLM analysis indicated that the general body size of both sexes and the appendage size of females increased significantly with increasing temperature; however, the coefficient of determination was very small. GLMM analysis indicated that body size only correlated with age, whereas appendage size was affected by age, temperature, rainfall, and sunshine. Annual growth rates were positively correlated with temperature. We concluded that body size variation was mainly caused by age structure and plasticity of the growth rate in P. przewalskii and did not follow Bergmann''s rule; however, females followed Allen''s rule. Future studies to investigate the effect of energy restriction are needed to further understand the relationship between growth rate and body size. We also suggest that further studies on thermal advantage and sexual selection may be helpful to understand appendage size variation in P. przewalskii.     

Mechanisms behind active trends in body size evolution of the Canidae (Carnivora: Mammalia)

Clade-level interactions can impart trends on observed characters. In this study, origination and extinction events were compiled for the three subfamilies of the Canidae (dogs): Hesperocyoninae, Borophaginae, and Caninae. These events were binned into 2-million-year time slices, and median body masses were calculated for each time slice. Originations and extinctions were classified as "large" or "small" relative to these median values. Likelihood ratios demonstrate that originations were significantly biased from random in four time slices, while extinctions were never significantly different from random. Two models were chosen by the Akaike Information Criterion to describe the evolutionary dynamics of canid body size. Both proposed a consistent, significant bias toward larger originations, punctuated by episodic "pulses" of increased bias toward larger originations and a Quaternary "pulse" favoring smaller originations, tracking the Quaternary diversification of foxlike canids. These pulses correspond in each subfamily to periods of rapid taxonomic diversification and the appearances of morphologies associated with hypercarnivorous diets. Together, the diversity data, the appearance of hypercarnivory, and the biases in originations document competitive interactions between Hesperocyoninae and Borophaginae and suggest that body size trends were driven, in part, by clade-level dynamics in the Canidae.     

软刺裸裂尻鱼的年龄鉴定

检测并比较了软刺裸裂尻鱼（Schizopygopsis malacanthus）鳞片、耳石、脊椎骨和背鳍条的年轮特征。结果表明,这4种材料上均具有年轮特征,以耳石最明显,且易于识别,为最好的年龄鉴定材料;鳞片上的年轮也较明显,但高龄鱼外围的年轮常挤在一起,使鉴定结果偏低;背鳍条上的环纹清晰,但边缘出现轮纹的重叠,影响年龄准确判读;脊椎骨上通常只能观察到比较有限的环纹,不适合用作年龄鉴定。     

Age determination of the perennial herb Lilium polyphyllum (Liliaceae)

This study aims to determine the age of individual plants of the perennial herb Lilium polyphyllum in its natural habitats. Plant age was successfully estimated as the number of years a seed takes to produce the first stem plus the number of remnants of old shoots visible on the basal plates of the bulbs. Plant age as well as morphological features of shoots and bulbs were recorded at one temperate and one high altitude site. There were significant differences between the sites with respect to plant height, leaf number, bulb diameter and weight. The results show that individuals of similar age differ in morphology between temperate and high altitude sites. At both sites, all flowering plants of L. polyphyllum were 10–12 years old.     

A pantodont (Mammalia) from the latest Puercan North American Land Mammal Age (earliest Paleocene) of the Western Interior,USA

Abstract

Discovery of an Alcidedorbignya-like isolated upper molar in an early Paleocene (latest Puercan, Puercan 3, North American Land Mammal Age) local fauna found in the Tullock Member of the Fort Union Formation in northeastern Montana has been cited in the paleontological literature. This fossil is described, and a new genus and species, Crustulus fontanus, are established. They add to the taxonomic diversity of Puercan 3 local faunas in the North America Western Interior. The tooth’s morphology including a deep ectoflexus, nearly parallel preparacrista and postmetacrista, and expansion of the postcingulum, suggests evolution to accommodate increased herbivory. The appearance of C. fontanus with no clearly related taxa in older Puercan or Lancian (latest Cretaceous) local faunas of the currently sampled areas of the Western Interior indicates it probably was yet another post-Cretaceous/Paleogene boundary immigrant into this region. The few characters preserved in the single upper molar strongly suggest but do not conclusively indicate phylogenetic affinities with pantodonts. Perhaps C. fontanus was a member of yet another lineage stemming from the common ancestry of pantodonts and tillodonts. It is the oldest record of this complex group in North America.

http://www.zoobank.org/urn:lsid:zoobank.org:act:3643EA78-9A1A-4A2A-BFAF-4C2B6355B834     

Rule reversal: Ecogeographical patterns of body size variation in the common treeshrew (Mammalia,Scandentia)

There are a number of ecogeographical “rules” that describe patterns of geographical variation among organisms. The island rule predicts that populations of larger mammals on islands evolve smaller mean body size than their mainland counterparts, whereas smaller‐bodied mammals evolve larger size. Bergmann's rule predicts that populations of a species in colder climates (generally at higher latitudes) have larger mean body sizes than conspecifics in warmer climates (at lower latitudes). These two rules are rarely tested together and neither has been rigorously tested in treeshrews, a clade of small‐bodied mammals in their own order (Scandentia) broadly distributed in mainland Southeast Asia and on islands throughout much of the Sunda Shelf. The common treeshrew, Tupaia glis, is an excellent candidate for study and was used to test these two rules simultaneously for the first time in treeshrews. This species is distributed on the Malay Peninsula and several offshore islands east, west, and south of the mainland. Using craniodental dimensions as a proxy for body size, we investigated how island size, distance from the mainland, and maximum sea depth between the mainland and the islands relate to body size of 13 insular T. glis populations while also controlling for latitude and correlation among variables. We found a strong negative effect of latitude on body size in the common treeshrew, indicating the inverse of Bergmann's rule. We did not detect any overall difference in body size between the island and mainland populations. However, there was an effect of island area and maximum sea depth on body size among island populations. Although there is a strong latitudinal effect on body size, neither Bergmann's rule nor the island rule applies to the common treeshrew. The results of our analyses demonstrate the necessity of assessing multiple variables simultaneously in studies of ecogeographical rules.