Three new extinct species from the endemic Philippine cloud rat radiation (Rodentia, Muridae, Phloeomyini)

Journal of Mammalogy, Journal Year: 2021, Volume and Issue: 102(3), P. 909 - 930

Published: Feb. 11, 2021

Abstract The 18 extant members of the Tribe Phloeomyini, “cloud rats,” constitute an endemic Philippine radiation arboreal herbivores that range in size from ca. g to 2.7 kg, most occurring cloud forest above 1,200 m elevation. Although calibrated phylogenies indicate Phloeomyini is estimated have begun diversifying within Philippines by 10–11 million years ago, no extinct fossil species been described, severely limiting our understanding this distinctive radiation. Our studies and subfossil small mammal assemblages lowland Callao Caves complex NE Luzon, Philippines, produced specimens date 67,000 BP Late Holocene (ca. 4,000 2,000 BP). We identify three we name as new assigned genera Batomys, Carpomys, Crateromys, distinguished congeners body size, dental other morphological features, occupancy a habitat (lowland over limestone) differs high-elevation mossy volcanic soils occupied their congeners. Batomys cagayanensis n. sp. known only two BP; Carpomys dakal Crateromys ballik were present Holocene. These add richness diversity large folivores, show specifically fauna mammals on Luzon was more diverse recent past than it currently, recently supported five giant rodents 1 kg or more). All occurred contemporaneously with Homo luzonensis, two, persisted until when multiple exotic species, both domestic invasive, introduced cultural practices (such making pottery) became evident, suggesting modern humans played role extinction.

Language: Английский

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Sperm competition and the evolution of sperm form and function in mammals

Reproduction in Domestic Animals, Journal Year: 2019, Volume and Issue: 54(S4), P. 14 - 21

Published: Oct. 1, 2019

Sperm competition is a powerful selective force that has influenced many reproductive traits in males and females although additional evolutionary explanations may help to understand the diversity of mammalian reproduction. morphology varies considerably mammals with extreme examples several rodent lineages which wide range sizes complex head morphologies have been identified. Mammalian spermatozoa also differ function, swimming velocity trajectory showing much divergence. Underlying processes mediating function received little attention so far, but differences timing proportion sperm undergoing capacitation or acrosomal exocytosis be related variation signalling processes. Furthermore, energy required for functions (such as motion, overall maintenance cell integrity) can produced consumed, following different patterns among species this could result forces. A more thorough understanding structure cells, underlying forces, us develop better methods assess them taking into account particulars generalities form performance. Such tests then become reliable estimations impact cryopreservation effect changes environment their relevance fertility.

Language: Английский

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Testicular Structure and Spermatogenesis in the Naked Mole-Rat Is Unique (Degenerate) and Atypical Compared to Other Mammals

Frontiers in Cell and Developmental Biology, Journal Year: 2019, Volume and Issue: 7

Published: Oct. 16, 2019

The naked mole-rat (NMR) queen controls reproduction in her eusocial colony by usually selecting one male for and suppressing gametogenesis all other males females. Simplified, polymorphic slow-swimming spermatozoa the NMR seem to have been shaped a low risk of sperm competition. We hypothesize that this unique mammalian social organization has had dramatic influence on testicular features spermatogenesis NMR. structure as well spermatogenic cell types its breeding, subordinate disperser were studied using light microscopy transmission electron microscopy. Even though basic design NMRs is similar most Afrotheria some rodents with intra-abdominal testes, Sertoli cells many atypical features. Seminiferous tubules are distended contain large volumes fluid while interstitial tissue cover about 50% surface area mainly composed Leydig cells. cytoplasm contains an extensive network membranes variety fluid-containing vesicles. Furthermore, form numerous phagosomes often appear accumulations myelin. Another unusual feature mature mitotic division. While main spermatogonia spermatocytes clearly identifiable, these poorly organized spermatids without typical intercellular bridges present. Spermatid heads be malformed disorganized chromatin, nuclear fragmentation ill-defined acrosome formed from star-like Golgi bodies. Rudimentary manchette development corresponds occurrence abnormal morphology. also spermiation modified produce demand short period time subsequently use "pump" flush into tubuli recti simplified rete testis. Despite difficulty finding cellular associations during spermatogenesis, six stages could described These further supports notion degenerative orthogenesis was selected due absence

Language: Английский

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Reproductive biology of the mice and rats (family Muridae) in New Guinea—diversity and evolution

Records of the Australian Museum, Journal Year: 2020, Volume and Issue: 72(5), P. 303 - 316

Published: Nov. 25, 2020

In New Guinea there are around 100 species of native rodents in the family Muridae that members two tribes, Hydromyini and Rattini, five divisions—the Hydromys, Uromys, Mallomys, Pogonomys, Rattus divisions. Here we review their basic reproductive biology so far as it can be determined from material available. We find females most Hydromys Uromys divisions have 4 nipples, Pogonomys division 6, whereas Mallomys nipple number across ranges 2 to up 12. The fetuses observed pregnant individuals all hydromyine was generally between 1 3 but three or even occasionally more, occurs. males, relative testes mass (RTM) usually 3% body mass, varied markedly only 0.4% Hyomys goliath 5% Pogonomys. spermatozoa divisions, like Australian these contained a head with an apical hook together ventral processes, marked interspecific differences occurred some having sperm processes others were no long hook. Sperm tail length 90 130 µm Chiruromys Xenuromys had lengths 150–153 µm. Male accessory sex glands similar except for preputial which appeared absent very large Hyomys. findings tails suggest selection high levels intermale competition hence multimale breeding systems species, variation gland size social organization.

Language: Английский

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Estimation of multiple male mating frequency using paternity skew: An example from a grey‐sided vole (Myodes rufocanus) population

Molecular Ecology Resources, Journal Year: 2019, Volume and Issue: 20(2), P. 444 - 456

Published: Nov. 18, 2019

Abstract Multiple male mating (MMM) causes sperm competition, which may play an important role in the evolution of reproductive traits. The frequency multiple paternity (MP), where males sire offspring within a single litter, has been used as index MMM frequency. However, MP is necessarily lower than magnitude difference between and depends on litter size (LS) fertilization probability skew (FPS), this be meaningfully large animals with small LSs. In study, we propose method to estimate using individual‐based model three variables (MP frequency, LS FPS). We incorporated observed data infer possible range FPS that cannot measured free‐living populations tested validity our set from grey‐sided vole ( Myodes rufocanus ) population hypothetical populations. was found 50 out 215 litters (23.3%) population, while estimated 67 (31.2%), certainty 59–88 (27.4%–40.9%). point estimation realized, limited practical range. use very effective at narrowing estimate. Our could contribute deeper understanding ecology

Language: Английский

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