Life history strategy of Lepraria borealis at an Antarctic inland site, Coal Nunatak

AbstractCoal Nunatak is an ice-free inland nunatak located on southern Alexander Island, adjacent to the west coast of the Antarctic Peninsula. Situated close to the Antarctic continent, it is characterized by harsh environmental conditions. Macroscopic colonization is restricted to micro-niches offering suitable conditions for a small number of lichens and mosses. The extreme environmental conditions place particular pressures on colonizers. Lepraria borealis is the dominant crustose lichen species present on Coal Nunatak, and shows distinctive features in its life history strategy, in particular expressing unusually low selectivity of the mycobiont towards potential photobionts. To assess selectivity, we measured algal DNA sequence polymorphism in a region of 480–660 bp of the nuclear internal transcribed spacer region of ribosomal DNA. We identified three different photobiont species, belonging to two different genera. We interpret this strategy as being advantageous in facilitating the colonization and community dominance of L. borealis under the isolation and extreme environmental conditions of Coal Nunatak.

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The influence of temperature on the life history of the Antarctic nematode Panagrolaimus davidi

Nematology ◽

10.1163/1568541044038641 ◽

2004 ◽

Vol 6 (6) ◽

pp. 883-890 ◽

Cited By ~ 8

Author(s):

Russell Millar ◽

David Wharton ◽

Ian Brown

Keyword(s):

Life History ◽

Life History Strategy ◽

Major Influence ◽

Free Living ◽

Egg Incubation ◽

Polar Species ◽

Threshold Temperatures ◽

Influence Of Temperature On ◽

History Of ◽

The Antarctic

AbstractPanagrolaimus davidi is a free-living microbivore, associated with moss and algal patches in coastal regions around Ross Island, Antarctica. In laboratory experiments, temperature had a major influence on P. davidi life history parameters. The optimal temperature occurred between 25 and 30°C and the temperature at which population growth ceased was estimated at 6.8°C. Threshold temperatures for developmental processes were in the range 4.1°C (for egg incubation) to 7.6°C (for generation time). The life history strategy of P. davidi shows r-selected features and is more similar to temperate free-living nematodes than to other polar species, which show K-selected features. In the Antarctic, P. davidi is forced to remain dormant for long periods and growth occurs intermittently when conditions allow, suggesting A selection. The life history of P. davidi thus exhibits both A and r-selected features.

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Crustal density structure of the Antarctic continent from constrained 3-D gravity inversion

10.5194/egusphere-egu2020-4427 ◽

2020 ◽

Author(s):

Fei Ji ◽

Qiao Zhang

Keyword(s):

Gravity Inversion ◽

Inversion Method ◽

Rift System ◽

Low Density ◽

Density Structure ◽

West Antarctica ◽

The West ◽

Antarctic Continent ◽

Crustal Density ◽

The Antarctic

Crustal density is a fundamental physical parameter that helps to reveal its composition and structure, and is also significantly related to the tectonic evolution and geodynamics. Based on the latest Bouguer gravity anomalies and the constrains of 3-D shear velocity model and surface heat flow data, the 3-D gravity inversion method, incorporating deep weight function, has been used to obtain the refined density structure over the Antarctic continent. Our results show that the density anomalies changes from -0.25 g/cm3 to 0.20 g/cm3. Due to the multi-phase extensional tectonics in Mesozoic and Cenozoic, the low density anomalies dominates in the West Antarctica, while the East Antarctica is characterized by high values of density anomalies. By comparing with the variations of effective elastic thickness, the inverted density structure correlates well with the lithospheric integrated strength. According to the mechanical strength and inverted density structure in the West Antarctic Rift System (WARS), our analysis found that except for the local area affected by the Cenozoic extension and magmatic activity, the crustal thermal structure in the WARS tends to be normal under the effect of heat dissipation. Finally, the low density anomalies features in West Antarctica extend to beneath the Transantarcitc Mountains (TAMs), however, we hypothesize that a single rift mechanism seems not be used to explain the entire TAMs range.

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On the Long-Term Climate Memory in the Surface Air Temperature Records over Antarctica: A Nonnegligible Factor for Trend Evaluation

Journal of Climate ◽

10.1175/jcli-d-14-00733.1 ◽

2015 ◽

Vol 28 (15) ◽

pp. 5922-5934 ◽

Cited By ~ 23

Author(s):

Naiming Yuan ◽

Minghu Ding ◽

Yan Huang ◽

Zuntao Fu ◽

Elena Xoplaki ◽

...

Keyword(s):

White Noise ◽

Surface Air Temperature ◽

Fluctuation Analysis ◽

The West ◽

Weather System ◽

Air Temperatures ◽

Antarctic Continent ◽

Temperature Records ◽

The Antarctic

Abstract In this study, observed temperature records of 12 stations from Antarctica island, coastline, and continental areas are analyzed by means of detrended fluctuation analysis (DFA). After Monte Carlo significance tests, different long-term climate memory (LTM) behaviors are found: temperatures from coastal and island stations are characterized by significant long-term climate memory whereas temperatures over the Antarctic continent behave more like white noise, except for the Byrd station, which is located in the West Antarctica. It is argued that the emergence of LTM may be dominated by the interactions between local weather system and external slow-varying systems (ocean), and therefore the different LTM behaviors between temperatures over the Byrd station and that over other continental stations can be considered as a reflection of the different climatic environments between West and East Antarctica. By calculating the trend significance with the effect of LTM taken into account, and further comparing the results with those obtained from assumptions of autoregressive (AR) process and white noise, it is found that 1) most of the Antarctic stations do not show any significant trends over the past several decades, and 2) more rigorous trend evaluation can be obtained if the effect of LTM is considered. Therefore, it is emphasized that for air temperatures over Antarctica, especially for the Antarctica coastline, island, and the west continental areas, LTM is nonnegligible for trend evaluation.

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Smelling the future: subtle life-history adjustments in response to environmental conditions and perceived transmission opportunities in a trematode

Parasitology ◽

10.1017/s003118201600192x ◽

2016 ◽

Vol 144 (4) ◽

pp. 464-474 ◽

Cited By ~ 1

Author(s):

C. LAGRUE ◽

R. RINNEVALLI ◽

R. POULIN

Keyword(s):

Life History ◽

Life Cycle ◽

Intermediate Host ◽

Definitive Host ◽

Environmental Conditions ◽

Life History Strategy ◽

Host Density ◽

Life Cycles ◽

Life History Strategies ◽

Priming Effects

SUMMARYA number of parasites with complex life cycles can abbreviate their life cycles to increase the likelihood of reproducing. For example, some trematodes can facultatively skip the definitive host and produce viable eggs while still inside their intermediate host. The resulting shorter life cycle is clearly advantageous when transmission probabilities to the definitive hosts are low. Coitocaecum parvum can mature precociously (progenesis), and produce eggs by selfing inside its amphipod second intermediate host. Environmental factors such as definitive host density and water temperature influence the life-history strategy adopted by C. parvum in their crustacean host. However, it is also possible that information about transmission opportunities gathered earlier in the life cycle (i.e. by cercariae-producing sporocysts in the first intermediate host) could have priming effects on the adoption of one or the other life strategy. Here we document the effects of environmental parameters (host chemical cues and temperature) on cercarial production within snail hosts and parasite life-history strategy in the amphipod host. We found that environmental cues perceived early in life have limited priming effects on life-history strategies later in life and probably account for only a small part of the variation among conspecific parasites. External cues gathered at the metacercarial stage seem to largely override potential effects of the environmental conditions experienced by early stages of the parasite.

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Giraffe nursing behaviour reflects environmental conditions

Behaviour ◽

10.1163/1568539x-00003413 ◽

2017 ◽

Vol 154 (1) ◽

pp. 115-129 ◽

Cited By ~ 9

Author(s):

Markéta Gloneková ◽

Pavla Jůnková Vymyslická ◽

Magdalena Žáčková ◽

Karolína Brandlová

Keyword(s):

Life History ◽

Czech Republic ◽

Food Intake ◽

Population Density ◽

Environmental Conditions ◽

Nature Reserve ◽

Life History Strategy ◽

Food Resources ◽

Large Area ◽

The Difference

Nursing behaviour is one component of mammalian life history strategy that demonstrates context-dependent flexibility within species. Wild giraffes live in groups and feed themselves over large area. In the zoo, giraffes are kept in enclosures with abundant food resources. We aimed to analyse whether the nursing behaviour of giraffes differs between the zoo and nature reserve and discuss which factor (food intake, presence of predators, population density) can explain the difference. We observed seven and four female–calf pairs in the Bandia reserve, Senegal, and in Prague Zoo, Czech Republic, respectively. Nursing bouts were less frequent and longer and calves were less successful in nursing solicitations in the reserve, as females there seemed to be more selective for nursing times and locations, likely due to presence of predators and differences in food intake. Allonursing occurred more frequently in the zoo which can be attributed to higher population density in captive conditions.

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