scholarly journals Male Horn Lack of Allometry May be Tied to Food Relocation Behaviour in Lifting Dung Beetles (Coleoptera, Scarabaeidae, Eucraniini)

Insects ◽  
2019 ◽  
Vol 10 (10) ◽  
pp. 359
Author(s):  
Palestrini ◽  
Barbero ◽  
Roggero
Keyword(s):  
Alternative Hypothesis ◽  
Dung Beetle ◽  
Growth Patterns ◽  
High Symmetry ◽  
Functional Constraints ◽  
Shape Variation ◽  
Reproductive Tactics ◽  
Closely Related Species ◽  
Scaling Relationships ◽  
Male Polymorphism

The small dung beetle tribe Eucraniini includes extremely specialized species that have been defined as “lifters” according to their food relocation behaviour. They are characterized by the presence of well-developed expansions on the head and pronotum, which can be included in the large and varied group of horns, whose presence is usually related to complex reproductive tactics. In this study, two closely related species, Anomiopsoides cavifrons and A. heteroclyta, were examined employing traditional and geometric morphometrics to test whether the Eucraniini has polymorphic males that might exhibit different reproductive tactics, as in the sister tribe Phanaeini, for which a male trimorphism was demonstrated. If also present in Eucraniini polyphenism could be considered a plesiomorphy common to the two clades. The inter- and intraspecific shape variation and object symmetry of the head and the scaling relationships between body size and traits were evaluated. Marked interspecific and small intraspecific differences in shape variation, high symmetry, and similar isometric growth patterns were shown in both species. The hypothesis of male polymorphism in Anomiopsoides was thus rejected. Instead, the results supported the alternative hypothesis that Eucraniini lacks male polymorphism, perhaps due to functional constraints affecting the shape of the structures involved in their peculiar food relocating behaviour.

Ecological Traits of the Eucalyptus L'hérit Subgenera Monocalyptus and Symphyomyrtus

1989 ◽  
Vol 37 (3) ◽  
pp. 207 ◽  
Author(s):  
IR Noble
Keyword(s):  
Growth Rate ◽  
Growth Rates ◽  
Root Morphology ◽  
Related Species ◽  
Early Growth ◽  
Growth Patterns ◽  
Leaf Chemistry ◽  
Ecological Traits ◽  
Closely Related Species ◽  
Genus Eucalyptus

The genus Eucalyptus L'Hérit. dominates most of the forests and woodlands of Australia. Many stands consist of intimate mixtures of species from different subgenera. The ecological traits of the two largest subgenera, Symphyomyrtus and Monocalyptus, are reviewed. Consistent differences in herbivore and parasite damage to leaves; in water relations; in tolerance to waterlogging, flooding, salinity and frost; in nutrient usage; in response to Phytophthora cinnamorni; and in early growth patterns are described. These can be summarised as differences in leaf chemistry; in root morphology, chemistry and activity; and in early growth rates. It is suggested that the differences in the ecological traits, and especially in the early growth rate, may help explain the coexistence of closely related species of similar habits in eucalypt communities.

scholarly journals Offspring viability benefits but no apparent costs of mating with high quality males

2010 ◽  
Vol 7 (3) ◽  
pp. 419-421 ◽  
Author(s):  
Leigh W. Simmons ◽  
Rebecca Holley
Keyword(s):  
Sexual Selection ◽  
Sexual Conflict ◽  
Alternative Hypothesis ◽  
Dung Beetle ◽  
Male Courtship ◽  
High Quality ◽  
Female Resistance ◽  
Genetic Quality ◽  
Onthophagus Taurus ◽  
Courtship Signals

Traditional models of sexual selection posit that male courtship signals evolve as indicators of underlying male genetic quality. An alternative hypothesis is that sexual conflict over mating generates antagonistic coevolution between male courtship persistence and female resistance. In the scarabaeine dung beetle Onthophagus taurus , females are more likely to mate with males that have high courtship rates. Here, we examine the effects of exposing females to males with either high or low courtship rates on female lifetime productivity and offspring viability. Females exposed to males with high courtship rates mated more often and produced offspring with greater egg–adult viability. Female productivity and lifespan were unaffected by exposure to males with high courtship rates. The data are consistent with models of sexual selection based on indirect genetic benefits, and provide little evidence for sexual conflict in this system.

scholarly journals Growth variability, dimensional scaling, and the interpretation of osteohistological growth data

2021 ◽  
Vol 17 (11) ◽  
Author(s):  
Thomas M. Cullen ◽  
Caleb M. Brown ◽  
Kentaro Chiba ◽  
Kirstin S. Brink ◽  
Peter J. Makovicky ◽  
...  
Keyword(s):  
Life History ◽  
Theoretical Models ◽  
Growth Patterns ◽  
Growth Data ◽  
Common Component ◽  
Growth Variability ◽  
Scaling Relationships ◽  
Dimensional Scaling ◽  
Taxonomic Description ◽  
History Of

Osteohistological data are commonly used to study the life history of extant and extinct tetrapods. While recent advances have permitted detailed reconstructions of growth patterns, physiology and other features using these data, they are most commonly used in assessments of ontogenetic stage and relative growth in extinct animals. These methods have seen widespread adoption in recent years, rapidly becoming a common component of the taxonomic description of new fossil taxa, but are often applied without close consideration of the sources of variation present or the dimensional scaling relationships that exist among different osteohistological measurements. Here, we use a combination of theoretical models and empirical data from a range of extant and extinct tetrapods to review sources of variability in common osteohistological measurements, their dimensional scaling relationships and the resulting interpretations that can be made from those data. In particular, we provide recommendations on the usage and interpretation of growth mark spacing/zonal thickness data, when these are likely to be unreliable, and under what conditions they can provide useful inferences for studies of growth and life history.

scholarly journals Drivers of inter-population variation in the gut microbiomes of sister species of Phanaeus dung beetles

2021 ◽  
Author(s):  
Claire C. Winfrey ◽  
Kimberly S. Sheldon
Keyword(s):  
Microbial Communities ◽  
Niche Partitioning ◽  
Dung Beetle ◽  
Character Displacement ◽  
Climatic Conditions ◽  
Population Variation ◽  
Sister Species ◽  
Closely Related Species ◽  
Temperature And Precipitation ◽  
Symbiotic Microbiota

ABSTRACTThe microbiome plays key roles in host physiology and ecology, but how the microbiome varies among populations of hosts is not well understood. However, different abiotic and biotic selection pressures across a species’ range likely lead to variation in the microbiome. In addition, symbiotic microbiota may differ more between closely-related species in sympatry than in allopatry if selection favors the reduction of interspecific competition. We investigated variation in the maternally-transmitted, beneficial gut microbiomes of Phanaeus vindex and P. difformis, sister species of dung beetle that compete for the same resources in sympatry and occur across diverse climatic conditions. We sampled and sequenced bacterial/archaeal 16S rDNA from guts of P. difformis and P. vindex collected across 17 sympatric and allopatric sites. Gut microbial communities were best predicted by temperature and precipitation, cattle present at sites, and spatial relationships among sites. Contrary to our hypotheses, we did not find that the gut microbial communities of P. vindex and P. difformis differed more in sympatry than in allopatry, nor that P. vindex, the more broadly distributed of the two species, exhibited greater microbiome turnover among populations. However, the gut microbiome of P. vindex shifted more between sympatric and allopatric populations than did that of P. difformis, suggesting character displacement. While more research is needed, it is possible that differences in gut microbial communities allow P. vindex and P. difformis to partition their niches in sympatry. Our work argues for further exploration of the gut microbiome’s potential role in niche partitioning and local adaptation.

scholarly journals Global elongation and high shape flexibility as an evolutionary hypothesis of accommodating mammalian brains into skulls

2020 ◽  
Author(s):  
Vera Weisbecker ◽  
Timothy Rowe ◽  
Stephen Wroe ◽  
Thomas E. Macrini ◽  
Kathleen L. S. Garland ◽  
...  
Keyword(s):  
Brain Size ◽  
Relative Volume ◽  
Shape Variation ◽  
Closely Related Species ◽  
Fossil Species ◽  
Mechanical Constraints ◽  
Statistical Shape ◽  
Mammalian Skull ◽  
And Function ◽  
Brain Shape

AbstractLittle is known about how the large brains of mammals are accommodated into the dazzling diversity of their skulls. It has been suggested that brain shape is influenced by relative brain size, that it evolves or develops according to extrinsic or intrinsic mechanical constraints, and that its shape can provide insights into its proportions and function. Here, we characterise the shape variation among 84 marsupial cranial endocasts of 57 species including fossils, using 3D geometric morphometrics and virtual dissections. Statistical shape analysis revealed four main patterns: over half of endocast shape variation ranges between elongate and straight to globular and inclined; little allometric variation with respect to centroid size, and none for relative volume; no association between locomotion and endocast shape; limited association between endocast shape and previously published histological cortex volumes. Fossil species tend to have smaller cerebral hemispheres. We find divergent endocast shapes in closely related species and within species, and diverse morphologies superimposed over the main variation. An evolutionarily and individually malleable brain with a fundamental tendency to arrange into a spectrum of elongate-to-globular shapes – possibly mostly independent of brain function - may explain the accommodation of brains within the enormous diversity of mammalian skull form.

Clast assembling, bed-forms and structure in gravel beaches

1998 ◽  
Vol 89 (4) ◽  
pp. 291-323 ◽  
Author(s):  
B. J. Bluck
Keyword(s):  
Grain Size ◽  
Turbulent Energy ◽  
Growth Patterns ◽  
Sediment Supply ◽  
Tidal Range ◽  
Shape Variation ◽  
Sedimentary Structures ◽  
Bedding Planes ◽  
Bed Forms ◽  
Barrier Beaches

AbstractBoth textural maturity and structure acquired by gravels on beaches are largely a response to the interaction between beach surface and wave-backwash energy. The turbulent energy driving the processes of particle rejection andselection at the surface of growing gravel sheets is partly controlled by the grain size of the sheet itself, so the process is to a large extent self-regulating. Beach surfaces are seen to comprise many discrete sheets of gravel competing for growth at their boundaries, but each characterised by a uniform or uniformly gradational texture.There are two main types of gravel sheet: (1) selection pavements which occur on low beach slopes, showing little areal grain-size or grain-shape variation, and (2) turbulence shadows which occur on steeper slopes and produce assemblages of clasts which may show perfect lateral shape and size gradation.The clasts which make up these various gravel sheets are termed ‘clast assemblages’, and such assemblages are the fundamental units from which beaches are constructed. Clast assemblages are classified in terms of their textural maturity—the degree to which they exhibit uniformity in clast size and shape. In beach sections they are, either singly or in combination, bounded by planes of discontinuity (bedding planes) to form beds.Repeated combinations of either clast assemblages or beds in a genetic association are regarded as sedimentary structures, many of which are diagnostic of the gravel beach environment. Growth of beaches involves the stacking of sedimentary structures, and four growth patterns have been identified. The beach structure is, therefore, classified in a hierarchy comprising clast assemblage, bed, structures and growth form, and it is the growth pattern which may be related to tidal range. P.ecognition of the processes which generate beach gravels through the structure of the gravels permits an analysis of the internal structure of major gravel bodies such as barrier beaches. It adds another set of criteria which may further lead to an understanding of the processes responsible for the generation and evolution of these large gravelforms.Three types of gravel lithosomes have been identified. (1) Regressive barrier bars which form a series of gravel ridges separated by lagoonal deposits. Barriers are built initially by swash bars which grow in size and coarsen through time to become wave-resistant forms. They form as a response to times when the sediment, unable to be evenly distributed and sorted on the beach surface, forms a discrete bar seaward of the active beach. This is the result of a punctuated or continuously high sediment supply compared with the wave energy available to disperse the sediment, or a falling sea level which shifts the locus of sediment accretion. (2) In contrast, regressive (prograding) gravel sheets form as a response to a continuous supply of sediment to the beach surface, allowing it to build seaward by the uniform accretion of sediment which is sorted and retained on its surface. (3) Gravel sheets produced in transgression are characterised by an abundance of spherical clasts and are often overlapped by the sand beaches which occur seaward of them.

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