Considerable Size Overlap Research Articles

Pelagic food-webs in a changing Arctic: a trait-based perspective suggests a mode of resilience

Arctic marine ecosystems support fisheries of significant and increasing economic and nutritional value. Commercial stocks are sustained by pelagic food webs with relatively few keystone taxa mediating energy transfer to higher trophic levels, and it remains largely unknown how these taxa will be affected by changing climate and the influx of boreal taxa. Calanus species store large quantities of lipids, making these zooplankton a critical link in marine food-webs. The Arctic Calanus species are usually larger and, importantly, have been suggested to contain disproportionately larger lipid stores than their boreal congeners. Continued climate warming and subsequent changes in primary production regimes have been predicted to lead to a shift from the larger, lipid-rich Arctic species, Calanus glacialis and Calanus hyperboreus, toward the smaller, boreal Calanus finmarchicus in the European Arctic, with negative consequences for top predators. Our data show that lipid content is closely related to body size for all three species, i.e. is not a species-specific trait, and that there is considerable overlap in size between C. finmarchicus and C. glacialis. A trait-based life-history model was used to examine an idealized scenario where, in a changed Arctic with a longer period of primary production, C. glacialis- and C. hyperboreus-like copepods are indeed replaced by C. finmarchicus-like individuals, whether through competition, plasticity, hybridization, or evolution. However, the model finds that transfer of energy from primary producers to higher predators may actually be more efficient in this future scenario, because of the changes in generation length and population turnover rate that accompany the body-size shifts. These findings suggest that Arctic marine food webs may be more resilient to climate-related shifts in the Calanus complex than previously assumed.

Mayr’s Swiftlet Aerodramus orientalis: A reinterpretation

Mayr’s Swiftlet Aerodramus orientalis was described from two specimens, one each from the islands of Guadalcanal and New Ireland, 880 km apart and with many other islands between. Both had blue gloss on the dorsal surface and a pale rump and, although one had naked tarsi, the other had feathered tarsi. It is here shown that these features are found on some Uniform Swiftlets A. vanikorensis , with which there is considerable size overlap, and so it is more consistent to subsume Mayr’s Swiftlet into the Uniform Swiftlet.

Techniques used for the isolation and characterization of extracellular vesicles: results of a worldwide survey

Extracellular vesicles (EVs) represent an important mode of intercellular communication. Research in this field has grown rapidly in the last few years, and there is a plethora of techniques for the isolation and characterization of EVs, many of which are poorly standardized. EVs are heterogeneous in size, origin and molecular constituents, with considerable overlap in size and phenotype between different populations of EVs. Little is known about current practices for the isolation, purification and characterization of EVs. We report here the first large, detailed survey of current worldwide practices for the isolation and characterization of EVs. Conditioned cell culture media was the most widely used material (83%). Ultracentrifugation remains the most commonly used isolation method (81%) with 59% of respondents use a combination of methods. Only 9% of respondents used only 1 characterization method, with others using 2 or more methods. Sample volume, sample type and downstream application all influenced the isolation and characterization techniques employed.

Use of external biometrics to sex Carrion Crow Corvus corone, Rook C. frugilegus and Western Jackdaw C. monedula in Northern England

Carrion Crow Corvus corone, Rook C. frugilegus and Western Jackdaw C. monedula culled as part of a predator control study in Northern England were sexed by inspecting internal reproductive organs and measured to determine whether external biometrics (wing, head‐plus‐bill and tarsus length) could be used to identify the sex of live birds. Tarsus length was found to vary between observers measuring the same bird so was not considered further. Due to considerable size overlap between the sexes it was not possible to sex all individuals correctly, particularly those less than a year old. The larger males and smaller females could be sexed with 85–93% accuracy, in adult birds using wing length of Carrion Crows of male >327 mm, female <309 mm; Rook male >320mm, female <307 mm; and Western Jackdaw male >246 mm, female <233 mm. Head‐plus‐bill length improved the number of birds sexed when used in combination with wing length for Carrion Crow and Rook.

In situ evidence for pre-capture qualitative selection in the tropical bivalve Lithophaga simplex

Few feeding studies have been performed on tropical bivalves, and in situ feeding studies are lacking altogether. We investigated retention efficiencies for natural particles in the coral-boring tropical mytilid Lithophaga simplex. Using the in situ InEx technique (Yahel et at. 2005; Limnol Oceanogr Methods 3:46-58) SCUBA divers collected samples from the water inhaled and exhaled by undisturbed bivalves at the coral reef of Eilat (Gulf of Aqaba). Particle retention efficiencies were determined using flow cytometry analysis of the paired water samples. The photosynthetic bacterium Synechococcus (0.9 +/- 0.1 mu m) and larger eukaryotic algae (1 to 10 mu m) were preferentially retained by the bivalve with removal efficiencies of up to 90 % (1996 to 2000: averages of 69 +/- 14 % and 60 +/- 17 %, respectively, n = 74 individual bivalves). The minute photosynthetic bacterium Prochlorococcus (0.4 +/- 0.1 mu m) was also moderately retained (41 +/- 19%). Only a small proportion of the non-photosynthetic bacteria (0.3 +/- 0.1 mu m) were retained (5 +/- 18%, median of 9%), despite their numerical dominance in the plankton and considerable size overlap with Prochlorococcus. Size-independent preferential retention was also observed within particle types: (1) L. simplex more efficiently retained Prochlorococcus and picoeukaryotic algal cells with higher chlorophyll content and (2) the small fraction of non-photo synthetic bacteria retained did not differ in size, but bad higher nucleic acid content (compared to the inhaled population) an indicator for viable and active bacteria. We conclude that particle retention is not strictly size-dependent in L. simplex, and probably involves other cell attributes such as cell surface properties and/or motility.

Size Overlap between Benign Melanocytic Choroidal Nevi and Choroidal Malignant Melanomas

To estimate size overlap between large choroidal nevi and small choroidal melanomas by using plotted frequency distributions of tumor size. Frequency distributions of largest linear basal diameter (LBD) and thickness (TH) of choroidal nevi and melanomas were plotted from published data and cases in the senior author's practice. Relative frequencies of choroidal nevi and melanomas were estimated from published data. Relative frequency distributions of the tumors were plotted to illustrate the extent of overlap between them. Comparison of plotted frequency distribution curves for thickness indicated that there were approximately 125 nevi for every melanoma in the TH range 1.5 to 2 mm, approximately 25 nevi for every melanoma in the TH range 2 to 2.5 mm, and approximately 5 nevi for every melanoma in the TH range 2.5 to 3 mm. Similarly, comparison of the plotted frequency distribution curves for LBD of these tumor types indicated that there were approximately 70 nevi for every choroidal melanoma in the LBD range 5 to 6 mm, approximately 10 nevi for every melanoma in the LBD range 6 to 7 mm, and approximately 3 nevi for every melanoma in the LBD range 7 to 8 mm. Because of the markedly greater cumulative lifetime incidence of choroidal nevi, the results of this analysis suggest considerable size overlap between larger nevi and smaller melanomas. Attempts to classify small melanocytic choroidal tumors clinically as benign nevi versus malignant melanomas on the basis of tumor size appear likely to result in multiple misclassifications.

Postlarval development of &lt;i&gt;Halicarcinus planatus&lt;/i&gt; females (Crustacea, Decapoda, Hymenosomatidae) in the estuary of the Deseado River, Argentina

This study analyses morphology and morphometric growth changes of Halicarcinus planatus females until their terminal moult, and characterises new juvenile stages. Monthly samples were collected in the estuary of the Deseado River, Santa Cruz Province, Argentina. Crabs were sampled between the mid-intertidal and upper subtidal levels. Intermoult stages were analysed in sub-samples of adolescents and adults, and the presence of epizoic organisms was registered. Juveniles and adults were reared at the laboratory and examined for moult changes. All 3376 crabs caught were females, indicating a clear spatial segregation between sexes. Five juvenile stages (immature 1, 2, 3, 4 and adolescent) and a mature one were recognised on the basis of morphology and morphometry. All immature stages differed in cephalothorax width (CW) and abdomen width (AW). Positive allometry was observed in some juvenile stages and isometry in an immature stage and in mature females. Adolescents and adults encompassed a wide range of sizes, and the considerable size overlap between them suggests an anomalous growth process. Moult staging analysis indicated that adolescents have a high incidence of pre-moult stages in winter, when the terminal moult occurs. The measurements performed in laboratory-reared females indicated no abnormal increases during the moult. The terminal moult occurs within a wide size range, perhaps in association with mating.

Body Form and Trackway Pattern in Australian Desert Monitors (Squamata: Varanidae): Comparing Zoological and Ichnological Diversity

Abstract To what extent does ichnological diversity (the number of distinctive trace fossil morphologies) serve as a proxy for zoological diversity (species richness of trackmakers in the living fauna) in footprint assemblages made by terrestrial lower vertebrates? This question was investigated in a study of body form and trackway features of monitor lizards (varanids) from the Western Australian desert. Body-shape parameters deemed likely to affect trackway pattern of seven varanid species were measured. These lizards differ in average adult size, but there is considerable size overlap between adults of small-bodied species and juveniles of large-bodied species. Although subtle species differences in body form were detected, these were largely swamped by intraspecific variability. Furthermore, the most distinctive features in which trails of monitor species differ reflect interspecific differences in foraging behavior rather than anatomical differences, and are features that would be difficult or imposs...

Body Form and Trackway Pattern in Australian Desert Monitors (Squamata: Varanidae): Comparing Zoological and Ichnological Diversity

Other| June 01, 2000 Body Form and Trackway Pattern in Australian Desert Monitors (Squamata: Varanidae): Comparing Zoological and Ichnological Diversity JAMES O. FARLOW; JAMES O. FARLOW 1Department of Geosciences, Indiana-Purdue University at Fort Wayne, IN 46805 Search for other works by this author on: GSW Google Scholar ERIC R. PIANKA ERIC R. PIANKA 2Integrative Biology, C0930, University of Texas, Austin, TX 78712-1064 Search for other works by this author on: GSW Google Scholar PALAIOS (2000) 15 (3): 235–247. https://doi.org/10.1669/0883-1351(2000)015<0235:BFATPI>2.0.CO;2 Article history accepted: 07 Feb 2000 first online: 03 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share MailTo Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation JAMES O. FARLOW, ERIC R. PIANKA; Body Form and Trackway Pattern in Australian Desert Monitors (Squamata: Varanidae): Comparing Zoological and Ichnological Diversity. PALAIOS 2000;; 15 (3): 235–247. doi: https://doi.org/10.1669/0883-1351(2000)015<0235:BFATPI>2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyPALAIOS Search Advanced Search Abstract To what extent does ichnological diversity (the number of distinctive trace fossil morphologies) serve as a proxy for zoological diversity (species richness of trackmakers in the living fauna) in footprint assemblages made by terrestrial lower vertebrates? This question was investigated in a study of body form and trackway features of monitor lizards (varanids) from the Western Australian desert. Body-shape parameters deemed likely to affect trackway pattern of seven varanid species were measured. These lizards differ in average adult size, but there is considerable size overlap between adults of small-bodied species and juveniles of large-bodied species. Although subtle species differences in body form were detected, these were largely swamped by intraspecific variability. Furthermore, the most distinctive features in which trails of monitor species differ reflect interspecific differences in foraging behavior rather than anatomical differences, and are features that would be difficult or impossible to recognize without actually capturing the trackmaker. These observations provide empirical support for the widely held belief that trace fossil diversity commonly under-represents zoological diversity. The degree to which this is so is likely to be influenced by trackmaker body size and metabolic physiology. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Comparative Cytometric and Microscopic Analyses of Oyster Hemocytes

Automated techniques for counting molluscan hemocytes and measuring certain of their characteristics are becoming more common, but there has not been a concerted attempt to compare results with more traditional microscopy. We compared electrical resistance (Coulter counter) and light-scatter (flow-cytometry) measurements of eastern oyster, Crassostrea virginica, hemocytes with those from phase-contrast light microscopy. Our findings showed that the clarity of results from the two automated measurements was inversely related to the complexity, in type and size, of the cell population being analyzed. Microscopy produced the most detailed information, but flow-cytometric measurements, even when relying on light scatter alone, clearly surpassed the discriminatory ability of the Coulter counter. Microscopic measurements documented considerable size overlap among morphologically different types of hemocytes. Because it measures size only, the Coulter counter is relatively insensitive to these differences. The flow cytometer consistently described three subpopulations: two granular and one agranular. Because of the wide range and overlap in hemocyte size and intracellular contents (the two criteria measured by light scatter) within individuals, however, we found only a loose correlation between subpopulation counts from microscopy and from flow cytometry. By combining light scatter with the flow cytometer's ability to detect specific fluorescent dyes and its capacity to physically sort cells according to defined parameters, however, we expect to greatly increase its usefulness for studying molluscan hemocytes.

Male Reproductive Behavior of the Social Wasp Polistes fascatus (Hymenoptera: Vespidae)

Abstract and SummaryPopulations of male Polistes fuscatus simultaneously exhibit two different mate‐locating tactics. Some males defend territories in female nesting and hibernation sites. These males frequently do not occupy the same territory each day, and they drag their gasters over perches, which may function to apply a secretion to the perch. Another segment of the population patrols large overlapping areas in female foraging sites. In contrast to territorial males, patrolling males do not rub their gasters on perches, and males seen on more than one day are tenacious to one area. Males in both sites are aggressive to other males and attempt to copulate with females. A laboratory study indicates that large males have an advantage in male‐male competition. The mean size of patrollers is smaller than that of territorial males, indicating that patrollers are competitively inferior males. Yet there is considerable size overlap of males between the two sites, suggesting that there is also overlap in the range of probability of mating success between the two sites.

Age Estimation of Warthog

Adult warthogs (Phacochoerus aethiopicus) present difficulties of age determination from dentition, as all molariform teeth except M3 may be shed at an early stage. The nature of growth and attrition of M3 makes this tooth difficult to interpret in terms of age by visual methods. An index of growth in length of the erupted crown divided by height of the tooth at the anterior of the crown was found to be approximately linear with age up to about 5 years. Assuming this relationship continues linearly, as the curves of growth and wear suggest, ages were estimated up to 10 years, compared with previous age determinations by other workers up to 4 years. J. WILDL. MANAGE. 38(2):229-233 Studies of the survival of warthogs, a specialized African suid, in the Akagera National Park, Rwanda, necessitated the determination of the ages at death of found skulls (Spinage 1972). Previous workers (Child et al. 1965, Bradley 1972, G. Clough, personal communication) have age-determined them up to only 4 years. This was considered inadequate for survival studies, and a method of determining age beyond 4 years had to be devised. The teeth are distinguished by a unique pattern of development first described by Owen (1845). The permanent M3 has a semipersistent pulp so that the tooth grows almost continuously while in use, the roots closing at a late stage (Fig. 1). As the antecedent teeth are shed at an early age, the final molar M3 assumes a much greater role than the other teeth. It bears most of the work load from middle-age or earlier, and in consequence is a larger tooth. It has been described by Van Hoepen and Van Hoepen (1932) (quoted by Middleton-Shaw [1940]), but these authors did not relate changes in the tooth to chronological age. Bigourdan (1948) presented criteria for age determination of warthogs in Senegal, w ich relied to a large extent on the disappearance of premolars and molars antecedent to M3. Child et al. (1965) considered this to be unreliable as fragments of these teeth may persist. These authors also pointed to considerable differences which could be found in the number of permanent teeth as follows: I 1/2 or 3; C 1/1; Pm 1, 2, or 3/1 or 2; M 3/3. They produced criteria for age determination up to 4 years, based on eruption time of the molars, growth in length of M3, and supporting measurements of canines and skull length. Skull were separated into male and female, but there was considerable overlap in size. Clough (Personal communication) was unable to find evidence of sexual dimorphism in skulls of known sex because of the wide variations in growth. Clough also used eruption and replacement criteria, determining ages up to approximately 4 years. Flower (1931) gave longevity records of 13.5 and 16.5 years for females in the Giza Zoo. The mean age of 11 animals greater than 3 years old in the London Zoo was 8.1 years and maximum longevity 12 years. It is clear that the potential survival of warthogs is well past 4 years, with a possible lifespan of 17. We are grateful to G. Clough for allowing us to quote his unpublished data, to F. E. Guinness for help in collecting and classify1 Present address: College of African Wildlife Management, Mweka, P. O. Box 3031, Moshi, Tanzania. J. Wildl. Manage. 38 (2):1974 229 This content downloaded from 157.55.39.221 on Mon, 03 Oct 2016 04:40:44 UTC All use subject to http://about.jstor.org/terms 230 WARTHOG AGE ESTIMATION Spinage and Jolly