Interspecific diversity of testes mass and sperm morphology in the Philippine chrotomyine rodents: implications for differences in breeding systems across the species

2019 ◽  
Vol 31 (4) ◽  
pp. 705 ◽  
Author(s):  
William G. Breed ◽  
Hazirah Hassan ◽  
Macarena Gonzalez ◽  
Hanna J. McLennan ◽  
Chris M. Leigh ◽  
...  
Keyword(s):  
Sperm Morphology ◽  
Sister Group ◽  
Breeding Systems ◽  
Long Tail ◽  
Apical Hook ◽  
Interspecific Differences ◽  
Murid Rodents ◽  
Order Of Magnitude ◽  
High Diversity ◽  
Interspecific Diversity

The high diversity of native Philippine murid rodents includes an old endemic group, the chrotomyines, which are the sister group of the Australasian hydromyines. Herein we detail their interspecific diversity of relative testes mass (RTM) and sperm morphology. We find that in chrotomyines, as in the Australasian hydromyines, testes mass relative to body mass differs by an order of magnitude across the species and ranges from a large RTM in Soricomys and Chrotomys species to a small RTM in Apomys. Sperm morphology is associated with these findings, with individuals in species of Soricomys and Chrotomys producing relatively larger spermatozoa with a prominent apical hook and long tail, whereas, by contrast, the Apomys species have a sperm head that either has a very short or no apical hook and a shorter tail. These findings indicate coevolution of RTM with sperm morphological traits across the species, with the marked interspecific differences in RTM suggesting differences in the intensity of intermale sperm competition and hence breeding system. Thus, we hypothesise that species of Soricomys and Chrotomys that produce more streamlined spermatozoa with longer tails have a polyandrous or promiscuous mating system, whereas the Apomys species, which produce smaller and less streamlined spermatozoa, may exhibit monogamy.

Sperm morphology of the Rattini – are the interspecific differences due to variation in intensity of intermale sperm competition?

2018 ◽  
Vol 30 (11) ◽  
pp. 1434 ◽  
Author(s):  
Tessa Pahl ◽  
Hanna J. McLennan ◽  
Yun Wang ◽  
Anang S. Achmadi ◽  
Kevin C. Rowe ◽  
...  
Keyword(s):  
Sexual Selection ◽  
Sperm Competition ◽  
Sperm Morphology ◽  
Tail Length ◽  
Sperm Head ◽  
Apical Hook ◽  
Interspecific Differences ◽  
Murine Rodent ◽  
Murine Rodents ◽  
Sperm Size

It is widely accepted that in mammals a causal relationship exists between postcopulatory sexual selection and relative testes mass of the species concerned, but how much it determines sperm size and shape is debatable. Here we detailed for the largest murine rodent tribe, the Rattini, the interspecific differences in relative testes mass and sperm form. We found that residual testes mass correlates with sperm head apical hook length as well as its angle, together with tail length, and that within several lineages a few species have evolved highly divergent sperm morphology with a reduced or absent apical hook and shorter tail. Although most species have a relative testes mass of 1–4%, these derived sperm traits invariably co-occur in species with much smaller relative testes mass. We therefore suggest that high levels of intermale sperm competition maintain a sperm head with a long apical hook and long tail, whereas low levels of intermale sperm competition generally result in divergent sperm heads with a short or non-existent apical hook and shorter tail. We thus conclude that sexual selection is a major selective force in driving sperm head form and tail length in this large tribe of murine rodents.

scholarly journals Greater sperm complexity in the Australasian old endemic rodents (Tribe: Hydromyini) is associated with increased levels of inter-male sperm competition

2017 ◽  
Vol 29 (5) ◽  
pp. 921 ◽  
Author(s):  
Hanna J. McLennan ◽  
Stefan Lüpold ◽  
Pete Smissen ◽  
Kevin C. Rowe ◽  
William G. Breed
Keyword(s):  
Sperm Competition ◽  
Sperm Morphology ◽  
Tail Length ◽  
Sperm Head ◽  
Sperm Tail ◽  
Apical Hook ◽  
Sexually Selected Traits ◽  
Male Sperm ◽  
Murid Rodents ◽  
Selected Traits

Spermatozoa exhibit considerable interspecies morphological variation across mammals, especially among murid rodents. In Australasia, most murids in the tribe Hydromyini have a spermatozoon with a highly complex head exhibiting an apical hook, characteristic of most murids, and two projections that extend from its upper concave surface, the ventral processes. In the present study we performed a phylogenetically controlled comparison of sperm morphology across 45 species of hydromyine rodents to test the hypothesis that the length and angle of both the apical hook and ventral processes, as well as the length of the sperm tail, increase with relative testes mass as a proxy for differences in levels of inter-male sperm competition. Although both sperm head protrusions exhibited considerable variation in their length and angle across species, only the angles increased significantly in relation to relative testes mass. Further, the length of the sperm flagellum was positively associated with relative testes mass. These results suggest that, in hydromyine rodents, the angle of the apical hook and ventral processes of the sperm head, as well as the sperm tail length, are likely to be sexually selected traits. The possible functional significance of these findings is briefly discussed.

Bechala sommeri Ilger & Brauckmann, 2012 enlightens the Namurian griffenfly diversity (Insecta: Odonatoptera: Bechalidae)

2012 ◽  
Vol 43 (2) ◽  
pp. 161-169 ◽  
Author(s):  
André Nel ◽  
Jan-Michael Ilger ◽  
Carsten Brauckmann ◽  
Jakub Prokop
Keyword(s):  
Ecological Niche ◽  
Type Species ◽  
Early Carboniferous ◽  
Sister Group ◽  
Late Devonian ◽  
Group Relationships ◽  
New Diagnosis ◽  
Devonian Age ◽  
Early Late ◽  
High Diversity

Bechala sommeriIlger & Brauckmann, 2012, the type species of the type genus of the early Late Carboniferous (Namurian) family Bechalidae Ilger & Brauckmann, 2012, is redescribed. It does not belong to the order Megasecoptera as previously proposed. The taxon is clearly attributable to Odonatoptera for the typical venation characters as CuA separating from MP obliquely, a true arculus with concave RP and convex MA emerging from a composite vein R+MA, short ScP, and presence of convex intercalaries IR2 and IR1 between the main branches of RP3/4, RP2 and RP1. We transfer this taxon with the monospecific family Bechalidae to Odonatoptera. A new diagnosis is given for Bechalidae and its type genus Bechala. Furthermore, the presence of an oblique subnodal crossvein very far from the ending of ScP and close to the base of RP2 confirms the hypothesis that the subnodus is a structure originally independent of the nodus with a different function in relation to wing tracheation. The Bechalidae are included in a clade (Meganeuridae–Sinierasipteridae–Bechalidae–Lapeyridae–Nodialata), in contrast to a sister group relationships between the two clades Meganisoptera (=Namurotypidae–Paralogidae–Kargalotypidae–Kohlwaldiidae–Meganeuridae) and Odonatoclada (=Lapeyridae–Nodialata), while the potential relationships between the Campylopteridae and the Lapeyridae and Nodialata are rejected. Bechala represents a ‘damselfly-like’ ecological niche in the Namurian, showing the high diversity of the earliest known Odonatoptera, strongly suggesting an Early Carboniferous, if not Late Devonian age for this pterygote clade.

Relationship between blood O2 content and catecholamine levels during hypoxia in rainbow trout and American eel

1992 ◽  
Vol 263 (2) ◽  
pp. R240-R249 ◽  
Author(s):  
S. F. Perry ◽  
S. D. Reid
Keyword(s):  
Rainbow Trout ◽  
Catecholamine Release ◽  
Plasma Catecholamine ◽  
American Eel ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Interspecific Differences ◽  
Arterial Blood ◽  
Order Of Magnitude ◽  
Catecholamine Levels

Plasma catecholamine levels and arterial blood respiratory variables were monitored in rainbow trout (Oncorhynchus mykiss) and American eel (Anguilla rostrata) acutely exposed (30 min) to graded levels of external hypoxia [water PO2 (PWO2) 20-90 Torr]. The experiments were designed to evaluate the factors controlling catecholamine mobilization in hypoxic fish and to elucidate the basis of marked interspecific differences. In trout, plasma catecholamine levels were unchanged when PWO2 remained above 50 Torr but increased markedly when PWO2 was lowered below this value; the predominant catecholamine released into the circulation was epinephrine. In eel, there was no such obvious PWO2 threshold for catecholamine release although plasma levels were consistently elevated above baseline only at PWO2 less than 35 Torr. The magnitude of the catecholamine release in eel was approximately an order of magnitude less than in trout. Unlike in trout, there was no increase in the plasma epinephrine-to-norepinephrine concentration ratio. During hypoxia, the relationship between arterial blood PO2 (PaO2) and PWO2 was similar in both species and thus could not explain the differences in the PWO2 thresholds for catecholamine release. In trout, the calculated PaO2 thresholds for catecholamine release were 25.3 (epinephrine) and 20.5 Torr (norepinephrine) whereas in eel the corresponding values were 12.5 and 11.6 Torr, respectively. These PaO2 thresholds were in good agreement with the in vivo values for PaO2 at half-maximal hemoglobin (Hb)-O2 saturation (P50) for trout and eel blood of 22.9 and 11.1 Torr, respectively. Thus both species displayed essentially equivalent catecholamine release thresholds when expressed in terms of arterial blood O2 content corresponding to approximately 45-60% Hb-O2 saturation.

Variation of sperm head shape and tail length in a species of Australian hydromyine rodent: the spinifex hopping mouse, Notomys alexis

2006 ◽  
Vol 18 (7) ◽  
pp. 797 ◽  
Author(s):  
M. Bauer ◽  
W. G. Breed
Keyword(s):  
Tail Length ◽  
Sperm Head ◽  
Filamentous Actin ◽  
Head Shape ◽  
Long Tail ◽  
Sperm Tail ◽  
Total Length ◽  
Murid Rodents ◽  
Species Specific ◽  
High Degree

In Australia, there are around 60 species of murid rodents that occur in the subfamily Hydromyinae, most of which produce highly complex, monomorphic, spermatozoa in which the head has an apical hook together with two ventral processes containing filamentous actin and a long tail of species-specific length. One of the few exceptions to this is the spinifex hopping mouse, Notomys alexis, whose spermatozoa have previously been shown to have pleiomorphic heads. In this study, the structural organisation of the sperm head has been investigated in more detail and the variability in length of the midpiece and total length of the sperm tail has been determined for this species. The findings confirm that pleiomorphic sperm heads are invariably present in these animals and that this variability is associated with that of the nucleus, although nuclear vacuoles were not evident. The total length of the sperm tail, as well as that of the midpiece, was also highly variable both within, as well as between, individual animals. The reason(s) for this high degree of variability in sperm morphology is not known but it may relate to a relaxation of the genetic control of sperm form owing to depressed levels of inter-male sperm competition.

Small mammal populations in a eucalypt forest affected by fire and drought. I. Long-term patterns in an era of climate change

2009 ◽  
Vol 36 (2) ◽  
pp. 143 ◽  
Author(s):  
Harry F. Recher ◽  
Daniel Lunney ◽  
Alison Matthews
Keyword(s):  
Small Mammals ◽  
Small Mammal ◽  
Ground Vegetation ◽  
Eucalypt Forest ◽  
Eastern Australia ◽  
Murid Rodents ◽  
Small Mammal Community ◽  
Order Of Magnitude ◽  
Antechinus Agilis

This paper reports a study of ground-dwelling, small mammals in coastal eucalypt forest in south-eastern Australia from 1970 through 2005. During this time, the study area burnt in an intense fire in December 1972 and was partially burnt in November 1980. Both fires were associated with prolonged drought. The mammals studied comprised two dasyurid marsupials, Antechinus agilis and A. swainsonii, two native murid rodents, Rattus fuscipes and R. lutreolus, and the introduced house mouse Mus musculus. After intensive sampling throughout the year from 1970 through 1972 to establish basic ecological and population parameters of the small mammal community, populations were sampled annually during late autumn and early winter before the onset of breeding. There were marked differences in the annual (autumn/winter) abundances of all species; numbers of A. agilis ranged from 4 to 142 individuals; A. swainsonii 0 to 43; R. fuscipes 4 to 54; R. lutreolus 0 to 11; M. musculus 0 to 23. Following the 1972 fire, numbers fell to the lowest level recorded during the study and each population subsequently disappeared from the plot between the 1973 and 1974 winter censuses. The less intense 1980 fire did not lead to extirpation, but numbers of A. agilis, A. swainsonii and R. fuscipes declined as drought conditions persisted through 1983. R. lutreolus occurred consistently only following the fires, when a grassy ground vegetation favoured by this species developed. Similarly, M. musculus colonised within two years of the fires and persisted on the plot for 3–4 years before disappearing. Following the fires, populations of the omnivorous R. fuscipes recovered first followed by the scansorial, insectivorous A. agilis and last by the fossorial, insectivorous A. swainsonii. Two primary conclusions emerged from this study. First, the intense fire of 1972 did not kill all the animals immediately, but led to the disappearance of each species from the plot over 18 months. Thus, intense fire had a delayed but catastrophic impact on small ground-dwelling mammals. The fluctuations in population levels, covering more than an order of magnitude, demonstrate that factors other than fire, such as rainfall and drought, drive the population dynamics of these small mammals. As stability and recovery are not features of local populations, long-term studies of benchmark populations are necessary to manage forest biodiversity.

Sperm Morphology of Murid Rodents From New-Guinea and the Solomon-Islands - Phylogenetic Implications

1995 ◽  
Vol 43 (1) ◽  
pp. 17 ◽  
Author(s):  
WG Breed ◽  
KP Aplin
Keyword(s):  
Sperm Morphology ◽  
Solomon Islands ◽  
New Guinea ◽  
Sperm Head ◽  
Lateral Face ◽  
Apical Process ◽  
Transmission Electron ◽  
Phylogenetic Implications ◽  
Murid Rodents ◽  
Head Morphology

Observations on sperm morphology from most species of murid rodents from New Guinea and the Solomon Islands, based on light microscopy, are presented. Transmission electron microscopy of spermatozoa for three species in two genera are also given. All Rattus species, Melomys lanosus, M. rattoides, Lorentzimys nouhuysi and Coccymys ruemmleri have sickle-shaped sperm heads and long sperm tails. In contrast, most of the other species have sperm with a broader lateral face and three ventral processes. These processes vary somewhat in size and shape, and in two Pogonomys and one Chiruromys species there is an extension of the nucleus into the most caudal of the three processes. Species of Anisomys and Hyomys have a sperm head with a broad lateral face but with only a single apical process. Abeomelomys sevia and Solomys salebrosus each have a distinct sperm head morphology unlike that of any other Australian murid; the latter species also has an extremely short sperm tail. Taxonomic and phylogenetic inferences are drawn from these data. Some of the phylogenetic conclusions are markedly divergent from traditional views, which are based on craniodental anatomy.

scholarly journals 3D shape of Orion A from Gaia DR2

2018 ◽  
Vol 619 ◽  
pp. A106 ◽  
Author(s):  
Josefa E. Großschedl ◽  
João Alves ◽  
Stefan Meingast ◽  
Christine Ackerl ◽  
Joana Ascenso ◽  
...  
Keyword(s):  
Molecular Cloud ◽  
Large Scale ◽  
Galactic Plane ◽  
Young Stellar Objects ◽  
Long Tail ◽  
Stellar Objects ◽  
Star Forming ◽  
3D Shape ◽  
Order Of Magnitude ◽  
High Column

We use the Gaia DR2 distances of about 700 mid-infrared selected young stellar objects in the benchmark giant molecular cloud Orion A to infer its 3D shape and orientation. We find that Orion A is not the fairly straight filamentary cloud that we see in (2D) projection, but instead a cometary-like cloud oriented toward the Galactic plane, with two distinct components: a denser and enhanced star-forming (bent) Head, and a lower density and star-formation quieter ∼75 pc long Tail. The true extent of Orion A is not the projected ∼40 pc but ∼90 pc, making it by far the largest molecular cloud in the local neighborhood. Its aspect ratio (∼30:1) and high column-density fraction (∼45%) make it similar to large-scale Milky Way filaments (“bones”), despite its distance to the galactic mid-plane being an order of magnitude larger than typically found for these structures.

A controller for safe, convenient operation of LaB6 emitters on electron-beam instruments

1983 ◽  
Vol 41 ◽  
pp. 408-409
Author(s):  
W. J. Abramson ◽  
H. W. Estry ◽  
L. F. Allard
Keyword(s):  
Electron Beam ◽  
Control System ◽  
Thermal Shock ◽  
Appropriate Care ◽  
Electron Guns ◽  
Tungsten Filaments ◽  
Order Of Magnitude ◽  
Main Components

LaB6 emitters are becoming increasingly popular as direct replacements for tungsten filaments in the electron guns of modern electron-beam instruments. These emitters offer order of magnitude increases in beam brightness, and, with appropriate care in operation, a corresponding increase in source lifetime. They are, however, an order of magnitude more expensive, and may be easily damaged (by improper vacuum conditions and thermal shock) during saturation/desaturation operations. These operations typically require several minutes of an operator's attention, which becomes tedious and subject to error, particularly since the emitter must be cooled during sample exchanges to minimize damage from random vacuum excursions. We have designed a control system for LaBg emitters which relieves the operator of the necessity for manually controlling the emitter power, minimizes the danger of accidental improper operation, and makes the use of these emitters routine on multi-user instruments.Figure 1 is a block schematic of the main components of the control system, and Figure 2 shows the control box.

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