The demographic and life‐history costs of fear: Trait‐mediated effects of threat of predation on Aedes triseriatus

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Seroprevalence of Toxoplasma gondii in wild kangaroos using an ELISA

Infection with Toxoplasma gondii is a significant problem in Australian marsupials, and can lead to devastating disease and predispose animals to predation. T. gondii infection in kangaroos is also of public health significance due to the kangaroo meat trade. A moderate seroprevalence of T. gondii was observed in a study of western grey kangaroos located in the Perth metropolitan area in Western Australia. Of 219 kangaroos tested, 15.5% (95%CI: 10.7–20.3) were positive for T. gondii antibodies using an ELISA developed to detect T. gondii IgG in macropod marsupials. When compared with the commercially available MAT (modified agglutination test), the ELISA developed was in absolute agreement and yielded a κ coefficient of 1.00. Of 18 kangaroos tested for the presence of T. gondii DNA by PCR, the 9 ELISA positive kangaroos tested PCR positive and the 9 ELISA negative kangaroos tested PCR negative indicating the ELISA protocol was both highly specific and sensitive and correlated 100% with the more labour intensive PCR assay.     

Intergeneric Relationships Among Macropodoidea (Metatheria: Diprotodontia) and The Chronicle of Kangaroo Evolution

The superfamily of kangaroos (Macropodoidea) is comprised of the subfamilies Propleopinae, Hypsiprymnodontinae, Paleopotoroinae, Potoroinae, Bulungamayinae, Balbarinae, Macropodinae, and Sthenurinae. Of these, Hypsiprymnodontinae, Potoroinae, and Macropodinae are extant. Competing phylogenetic hypotheses unite potoroines with either hypsiprymnodontines or macropodines, with most recent workers following a classificatory scheme that recognizes Hypsiprymnodontidae (hypsiprymnodontines) and Macropodidae (macropodines + potoroines). To address phylogenetic relationships among living macropodoids, we analyzed sequences from three mitochondrial genes (12S rRNA, tRNA valine, 16S rRNA) and one nuclear gene (protamine P1). MtDNA and protamine P1 both support a basal split of Hypsiprymnodon from other macropodoids rather than an association of Hypsiprymnodon with potoroines. This suggests that bipedal hopping and a complex stomach evolved once among macropodids. Monophyly of the Macropodinae is supported. Among macropodines, there is support for a Dorcopsis-Dorcopsulus association. Potoroine monophyly is less clear, although among potoroines there is support for an association of Bettongia and Aepyprymnus. Divergence times were estimated using 12S rRNA, tRNA-valine, and 16S rRNA transversions and suggest that kangaroos separated from a possum-like ancestor approximately 38–44 million years ago. Hypsiprymnodon diverged from other macropodoids approximately 34 to 38 million years ago. In agreement with the fossil record, the diversification of potoroines predates the diversification of macropodines. The latter have radiated in association with the development of a more arid climate and emergent grasslands over the Australian continent.     

Red kangaroos (<Emphasis Type="Italic">Macropus rufus</Emphasis>) receive an antipredator benefit from aggregation

For species that cannot seek cover to escape predators, aggregation becomes an important strategy to reduce predation risk. However, aggregation may not be entirely beneficial because aggregated animals may compete for access to limited resources and might even attract predators. Available evidence suggests that foraging competition influences time allocation in large-bodied macropodid marsupials, but previous studies have focused primarily on species in areas with protective cover. We studied red kangaroos, a species often found in open country without noticeable cover, to determine whether they experienced a net benefit by aggregation. Red kangaroos varied their time allocation as a function of group size and, importantly, more variation in time allocation to vigilance and foraging was explained by non-linear models than by linear models. This suggests red kangaroos directly translated the reduction of predation risk brought about by aggregation into greater time foraging and less time engaged in vigilance. We infer that red kangaroos received a net benefit by aggregation. Social species living in the open may be generally expected to rely on others to help manage predation risk. Communicated by K. Kotrschal     

Size and sex of cricket prey predict capture by a sphecid wasp

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Distal Humeral Morphology Indicates Locomotory Divergence in Extinct Giant Kangaroos

Previous studies of the morphology of the humerus in kangaroos showed that the shape of the proximal humerus could distinguish between arboreal and terrestrial taxa among living mammals, and that the extinct “giant” kangaroos (members of the extinct subfamily Sthenurinae and the extinct macropodine genus Protemnodon) had divergent humeral anatomies from extant kangaroos. Here, we use 2D geometric morphometrics to capture the shape of the distal humerus in a range of extant and extinct marsupials and obtain similar results: sthenurines have humeral morphologies more similar to arboreal mammals, while large Protemnodon species (P. brehus and P. anak) have humeral morphologies more similar to terrestrial quadrupedal mammals. Our results provide further evidence for prior hypotheses: that sthenurines did not employ a locomotor mode that involved loading the forelimbs (likely employing bipedal striding as an alternative to quadrupedal or pentapedal locomotion at slow gaits), and that large Protemnodon species were more reliant on quadrupedal locomotion than their extant relatives. This greater diversity of locomotor modes among large Pleistocene kangaroos echoes studies that show a greater diversity in other aspects of ecology, such as diet and habitat occupancy.

     

Larvae of cryptic species of Anopheles gambiae respond differently to cues of predation risk

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PARALLEL EVOLUTION OF HAND ANATOMY IN KANGAROOS AND VOMBATIFORM MARSUPIALS: FUNCTIONAL AND EVOLUTIONARY IMPLICATIONS

Abstract:  The anatomy of the mammalian hand is exposed to an intriguing interplay between phylogeny and function, and provides insights on phylogenetic affinities as well as locomotory habits of extinct species. Within the marsupial order Diprotodontia, terrestrial plantigrade quadrupedalism evolved twice, in the mostly extinct vombatiforms and in extant macropodoids. To assess the influence of functional and phylogenetic signal on the manus in these two clades, manual anatomy and digital proportions in specimens of eight extinct and three extant vombatiforms were investigated and compared with extant macropodoids and extant possums. The results reveal extensive parallelisms in the carpal region of vombatiforms and macropodoids, including flattened distal metacarpal facets, reduction of the palmar process of the hamatum, reduction of mid-wrist joint curve, extensive hamatum/scaphoid contact, and absence of a lunatum. These transformations appear to be related to stabilization of the wrist for plantigrade locomotion. Vombatiforms are apomorphic in scaphoid and triquetrum anatomy and their metacarpals are much more gracile than in other Diprotodontia. Manual diversity is greater in vombatiforms than in macropodoids, as probably was locomotor diversity. Digital proportions as well as wrist anatomy divide the extinct vombatiforms into species resembling arboreal diprotodontians, whereas others group with terrestrial quadrupedal kangaroos and wombats. The latter is suggested to be owing to plantigrade locomotion and/or large size. Carpal anatomy and digital proportions suggest that a range of earlier diverging vombatiforms may have been arboreal or scansorial. As such, we propose that the ancestor of extant vombatiforms (koalas and wombats) may have been arboreal, an option that deserves consideration in the reconstruction of vombatiform evolution.     

Consequences of temperature and temperature variability on swimming activity,group structure,and predation of endangered delta smelt

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Modifying the PEG model for Mediterranean lakes – no biological winter and strong fish predation

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Unifying principles in terrestrial locomotion: do hopping Australian marsupials fit in?

Mammalian terrestrial locomotion has many unifying principles. However, the Macropodoidea are a particularly interesting group that exhibit a number of significant deviations from the principles that seem to apply to other mammals. While the properties of materials that comprise the musculoskeletal system of mammals are similar, evidence suggests that tendon properties in macropodoid marsupials may be size or function dependent, in contrast to the situation in placental mammals. Postural differences related to hopping versus running have a dramatic effect on the scaling of the pelvic limb musculoskeletal system. Ratios of muscle fibre to tendon cross-sectional areas for ankle extensors and digital flexors scale with positive allometry in all mammals, but exponents are significantly higher in macropods. Tendon safety factors decline with increasing body mass in mammals, with eutherians at risk of ankle extensor tendon rupture at a body mass of about 150 kg, whereas kangaroos encounter similar problems at a body mass of approximately 35 kg. Tendon strength appears to limit locomotor performance in these animals. Elastic strain energy storage in tendons is mass dependent in all mammals, but exponents are significantly larger in macropodid. Tibial stresses may scale with positive allometry in kangaroos, which result in lower bone safety factors in macropods compared to eutherian mammals.     

Sexual size dimorphism and the integration of phenotypically plastic traits

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Migratory herds of wildebeests and zebras indirectly affect calf survival of giraffes

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Contemporary trait change in a classic ecological experiment: rapid decrease in alewife gill‐raker spacing following introduction to an inland lake

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Osmotic stress decreases complexity underlying the electrophysiological dynamic in soybean

• Studies on plant electrophysiology are mostly focused on specific traits of single cells. Inspired by the complexity of the signalling network in plants, and by analogy with neurons in human brains, we sought evidence of high complexity in the electrical dynamics of plant signalling and a likely relationship with environmental cues.
• An EEG‐like standard protocol was adopted for high‐resolution measurements of the electrical signal in Glycine max seedlings. The signals were continuously recorded in the same plants before and after osmotic stimuli with a ?2 MPa mannitol solution. Non‐linear time series analyses methods were used as follows: auto‐correlation and cross‐correlation function, power spectra density function, and complexity of the time series estimated as Approximate Entropy (ApEn).
• Using Approximate Entropy analysis we found that the level of temporal complexity of the electrical signals was affected by the environmental conditions, decreasing when the plant was subjected to a low osmotic potential. Electrical spikes observed only after stimuli followed a power law distribution, which is indicative of scale invariance.
• Our results suggest that changes in complexity of the electrical signals could be associated with water stress conditions in plants. We hypothesised that the power law distribution of the spikes could be explained by a self‐organised critical state (SOC) after osmotic stress.

     

Foraging behavior of three Tasmanian macropodid marsupials in response to present and historical predation threat

It is often essential to understand historical selection regimes to explain current traits. We studied antipredator behavior of three Tasmanian macropodid marsupials – Forester kangaroos Macropus giganteus , Bennett's wallabies M. rufogriseus , and Tasmanian pademelons Thylogale billardierii – to understand how antipredator behavior functions in a relatively intact predator community. We also compared behavior of the kangaroos and wallabies on a predator-free island where they were translocated from mainland Tasmania 30 yr ago. Both species allowed humans to get closer to them on the predator-free island; a finding consistent with a reduced risk of predation on the island. Neither kangaroos, nor wallabies, exhibited group size effects – they did not modify time allocated to foraging or antipredator vigilance as a function of group size at either site. Nor did overall time allocation vary in any consistent way. In contrast, mainland Australian sibling-species of Forester kangaroos and Bennett's wallabies have both been reported to have group size effects. It is possible either that the extinction of the thylacine Thylacinus cynocephalus in the last century has led to an evolutionary loss of group size effects and other antipredator behavior, or that thylacines were never that important a predator on Tasmanian subspecies. In contrast, Tasmanian pademelons studied on the Tasmanian mainland modified time allocation as a function of group size suggesting that they perceived safety in numbers. Pademelons, because of their body size, are relatively more vulnerable than larger-bodied macropodids to the rich community of marsupial carnivores in Tasmania, and used a mix of social and individual strategies to manage predation risk.     

Locomotion in Extinct Giant Kangaroos: Were Sthenurines Hop-Less Monsters?

Sthenurine kangaroos (Marsupialia, Diprotodontia, Macropodoidea) were an extinct subfamily within the family Macropodidae (kangaroos and rat-kangaroos). These “short-faced browsers” first appeared in the middle Miocene, and radiated in the Plio-Pleistocene into a diversity of mostly large-bodied forms, more robust than extant forms in their build. The largest (Procoptodon goliah) had an estimated body mass of 240 kg, almost three times the size of the largest living kangaroos, and there is speculation whether a kangaroo of this size would be biomechanically capable of hopping locomotion. Previously described aspects of sthenurine anatomy (specialized forelimbs, rigid lumbar spine) would limit their ability to perform the characteristic kangaroo pentapedal walking (using the tail as a fifth limb), an essential gait at slower speeds as slow hopping is energetically unfeasible. Analysis of limb bone measurements of sthenurines in comparison with extant macropodoids shows a number of anatomical differences, especially in the large species. The scaling of long bone robusticity indicates that sthenurines are following the “normal” allometric trend for macropodoids, while the large extant kangaroos are relatively gracile. Other morphological differences are indicative of adaptations for a novel type of locomotor behavior in sthenurines: they lacked many specialized features for rapid hopping, and they also had anatomy indicative of supporting their body with an upright trunk (e.g., dorsally tipped ischiae), and of supporting their weight on one leg at a time (e.g., larger hips and knees, stabilized ankle joint). We propose that sthenurines adopted a bipedal striding gait (a gait occasionally observed in extant tree-kangaroos): in the smaller and earlier forms, this gait may have been employed as an alternative to pentapedal locomotion at slower speeds, while in the larger Pleistocene forms this gait may have enabled them to evolve to body sizes where hopping was no longer a feasible form of more rapid locomotion.     

Weed seed availability,carabid intraspecific interference and their interaction drive weed seed consumption by carabid beetles

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Evaluating the link between predation and pest control services in the mite world

1. Pest regulation by natural enemies has a strong potential to reduce the use of synthetic pesticides in agroecosystems. However, the effective role of predation as an ecosystem service remains largely speculative, especially with minute organisms such as mites.
2. Predatory mites are natural enemies for ectoparasites in livestock farms. We tested for an ecosystem level control of the poultry pest Dermanyssus gallinae by other mites naturally present in manure in poultry farms and investigated differences among farming practices (conventional, free‐range, and organic).
3. We used a multiscale approach involving (a) in vitro behavioral predation experiments, (b) arthropod inventories in henhouses with airborne DNA, and (c) a statistical model of covariations in mite abundances comparing farming practices.
4. Behavioral experiments revealed that three mites are prone to feed on D. gallinae. Accordingly, we observed covariations between the pest and these three taxa only, in airborne DNA at the henhouse level, and in mites sampled from manure. In most situations, covariations in abundances were high in magnitude and their sign was positive.
5. Predation on a pest happens naturally in livestock farms due to predatory mites. However, the complex dynamics of mite trophic network prevents the emergence of a consistent assemblage‐level signal of predation. Based on these results, we suggest perspectives for mite‐based pest control and warn against any possible disruption of ignored services through the application of veterinary drugs or pesticides.