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Journal Cover   Conservation Physiology
  This is an Open Access Journal Open Access journal
   ISSN (Online) 2051-1434
   Published by Oxford University Press (OUP) Homepage  [315 journals]
  • Physiological effects of heat stress on Hawaiian picture-wing Drosophila:
           genome-wide expression patterns and stress-related traits

    • Authors: Uy, K. L; LeDuc, R, Ganote, C, Price, D. K.
      Pages: cou062 - cou062
      Abstract: Climate change is compounding the threats to the future of biodiversity, already impacted by habitat loss, invasive species and diseases. In the Hawaiian Islands, many of the endemic species have narrow habitat ranges that make them especially vulnerable to climate change. The Hawaiian Drosophila, a remarkably diverse group of species with 11 listed as federally endangered, are thought to be sensitive to temperature changes. To examine the species differences in sensitivity of Hawaiian picture-wing Drosophila to temperature changes, wild populations of Drosophila sproati, a relatively common species, and Drosophila silvestris, a rare species, were collected from two locations on Hawaii Island and bred in common laboratory conditions. Adult flies were exposed to hot and cold temperatures and compared with adult flies at control temperatures. Drosophila silvestris adults were less tolerant to heat stress than D. sproati for both survival and sperm mobility. In contrast, D. silvestris adults were more tolerant to cold stress than D. sproati for adult survival. The expression of 4950 Gene Ontology annotated gene transcripts was also analysed in high-temperature-treated and control males to identify candidate genes related to heat tolerance. There were more than twice as many transcripts differentially expressed after high temperature treatment for D. silvestris (246 transcripts) as for D. sproati (106 transcripts), with 13 Gene Ontology terms enriched between temperatures for D. silvestris and merely three in D. sproati. The combined results are consistent with D. sproati occurring more widely today as well as occurring at lower elevations than D. silvestris and with a genetically based temperature response, which is more severe in D. silvestris at high temperatures than that in D. sproati. These experiments demonstrate the potential for different capacities of species to adapt to future climate change conditions as well as providing an explanation for historical changes in the distribution of species.
      PubDate: 2015-02-18T21:12:54-08:00
      DOI: 10.1093/conphys/cou062
      Issue No: Vol. 3, No. 1 (2015)
  • Predator-induced renesting and reproductive effort in indigo buntings:
           more work for less pay'

    • Authors: Morris, D. L; Faaborg, J, Washburn, B. E, Millspaugh, J. J.
      Pages: cou063 - cou063
      Abstract: Renesting after nest predation is ultimately an adaptive response to increase productivity in birds. However, renesting also increases reproductive effort to replace lost clutches. We investigated the consequences of this increased reproductive effort by determining whether renesting in female indigo buntings (Passerina cyanea) is associated with a decline in body condition (size-corrected mass) and haematocrit and an increase in stress hormones and whether renesting or maternal body condition is associated with a decline in productivity (clutch size, nestling body condition). Next, because a consequence of multiple renesting attempts is a prolonged breeding season and later timing, we predicted that a population of post-breeding females and juveniles would have lower body condition in fragmented forest than in contiguous forest owing to higher nest predation and frequency of renesting. Both forest types were settled by females of similar condition. Nest survival was lower in fragmented forest, where a higher proportion of females failed their first attempt and the breeding season was 2 weeks longer. Compared with females on their first attempt, renesting females had lower body condition and haematocrit and higher corticosterone concentrations. Lower maternal body condition was associated with higher concentrations of corticosterone, lower nestling body condition and smaller clutches. Clutch size was lower in renests and in fragmented forest. Nestling condition was lower in renests but did not vary greatly with forest type. Despite a prolonged breeding season in the fragmented forest, post-breeding females and hatch-year birds were in similar condition in both forest types. Our results suggest that the indirect effects of nest predation on maternal and offspring condition pose additional individual-level costs that have not been considered in the context of fragmentation studies. We discuss how predator-induced renesting could have additional demographic consequences by prolonging the breeding season and prompting seasonal interactions or carry-over effects that could impact populations.
      PubDate: 2015-02-04T23:22:59-08:00
      DOI: 10.1093/conphys/cou063
      Issue No: Vol. 3, No. 1 (2015)
  • Migration depth and residence time of juvenile salmonids in the forebays
           of hydropower dams prior to passage through turbines or juvenile bypass
           systems: implications for turbine-passage survival

    • Authors: Li, X; Deng, Z. D, Brown, R. S, Fu, T, Martinez, J. J, McMichael, G. A, Skalski, J. R, Townsend, R. L, Trumbo, B. A, Ahmann, M. L, Renholds, J. F.
      Pages: cou064 - cou064
      Abstract: Little is known about the three-dimensional depth distributions in rivers of individually marked fish that are in close proximity to hydropower facilities. Knowledge of the depth distributions of fish approaching dams can be used to understand how vulnerable fish are to injuries such as barotrauma as they pass through dams. To predict the possibility of barotrauma injury caused by pressure changes during turbine passage, it is necessary to understand fish behaviour relative to acclimation depth in dam forebays as they approach turbines. A guiding study was conducted using high-resolution three-dimensional tracking results of salmonids implanted with Juvenile Salmon Acoustic Telemetry System transmitters to investigate the depth distributions of subyearling and yearling Chinook salmon (Oncorhynchus tshawytscha) and juvenile steelhead (Oncorhynchus mykiss) passing two dams on the Snake River in Washington State. Multiple approaches were evaluated to describe the depth at which fish were acclimated, and statistical analyses were performed on large data sets extracted from ~28 000 individually tagged fish during 2012 and 2013. Our study identified patterns of depth distributions of juvenile salmonids in forebays prior to passage through turbines or juvenile bypass systems. This research indicates that the median depth at which juvenile salmonids approached turbines ranged from 2.8 to 12.2 m, with the depths varying by species/life history, year, location (which dam) and diel period (between day and night). One of the most enlightening findings was the difference in dam passage associated with the diel period. The amount of time that turbine-passed fish spent in the immediate forebay prior to entering the powerhouse was much lower during the night than during the day. This research will allow scientists to understand turbine-passage survival better and enable them to assess more accurately the effects of dam passage on juvenile salmon survival.
      PubDate: 2015-02-03T17:14:17-08:00
      DOI: 10.1093/conphys/cou064
      Issue No: Vol. 3, No. 1 (2015)
  • Predicting future thermal habitat suitability of competing native and
           invasive fish species: from metabolic scope to oceanographic modelling

    • Authors: Marras, S; Cucco, A, Antognarelli, F, Azzurro, E, Milazzo, M, Bariche, M, Butenschon, M, Kay, S, Di Bitetto, M, Quattrocchi, G, Sinerchia, M, Domenici, P.
      Pages: cou059 - cou059
      Abstract: Global increase in sea temperatures has been suggested to facilitate the incoming and spread of tropical invaders. The increasing success of these species may be related to their higher physiological performance compared with indigenous ones. Here, we determined the effect of temperature on the aerobic metabolic scope (MS) of two herbivorous fish species that occupy a similar ecological niche in the Mediterranean Sea: the native salema (Sarpa salpa) and the invasive marbled spinefoot (Siganus rivulatus). Our results demonstrate a large difference in the optimal temperature for aerobic scope between the salema (21.8°C) and the marbled spinefoot (29.1°C), highlighting the importance of temperature in determining the energy availability and, potentially, the distribution patterns of the two species. A modelling approach based on a present-day projection and a future scenario for oceanographic conditions was used to make predictions about the thermal habitat suitability (THS, an index based on the relationship between MS and temperature) of the two species, both at the basin level (the whole Mediterranean Sea) and at the regional level (the Sicilian Channel, a key area for the inflow of invasive species from the Eastern to the Western Mediterranean Sea). For the present-day projection, our basin-scale model shows higher THS of the marbled spinefoot than the salema in the Eastern compared with the Western Mediterranean Sea. However, by 2050, the THS of the marbled spinefoot is predicted to increase throughout the whole Mediterranean Sea, causing its westward expansion. Nevertheless, the regional-scale model suggests that the future thermal conditions of Western Sicily will remain relatively unsuitable for the invasive species and could act as a barrier for its spread westward. We suggest that metabolic scope can be used as a tool to evaluate the potential invasiveness of alien species and the resilience to global warming of native species.
      PubDate: 2015-01-21T00:54:52-08:00
      DOI: 10.1093/conphys/cou059
      Issue No: Vol. 3, No. 1 (2015)
  • Detection of oocyte perivitelline membrane-bound sperm: a tool for avian
           collection management

    • Authors: Croyle, K. E; Durrant, B. S, Jensen, T.
      Pages: cou060 - cou060
      Abstract: The success and sustainability of an avian breeding programme depend on managing productive and unproductive pairs. Given that each breeding season can be of immeasurable importance, it is critical to resolve pair fertility issues quickly. Such problems are traditionally diagnosed through behavioural observations, egg lay history and hatch rates, with a decision to re-pair generally taking one or more breeding seasons. In pairs producing incubated eggs that show little or no signs of embryonic development, determining fertility is difficult. Incorporating a technique to assess sperm presence on the oocyte could, in conjunction with behaviour and other data, facilitate a more timely re-pair decision. Detection of perivitelline membrane-bound (PVM-bound) sperm verifies successful copulation, sperm production and sperm functionality. Alternatively, a lack of detectable sperm, at least in freshly laid eggs, suggests no mating, lack of sperm production/function or sperm–oviduct incompatibility. This study demonstrated PVM-bound sperm detection by Hoechst staining in fresh to 24-day-incubated exotic eggs from 39 species representing 13 orders. However, a rapid and significant time-dependent loss of detectable PVM-bound sperm was observed following incubation of chicken eggs. The PCR detection of sperm in seven species, including two bacterially infected eggs, demonstrated that this method was not as reliable as visual detection using Hoechst staining. The absence of amplicons in visually positive PVMs was presumably due to large PVM size and low sperm count, resulting in DNA concentrations too low for standard PCR detection. In summary, this study demonstrated the feasibility and limitations of using PVM-bound sperm detection as a management tool for exotic avian species. We verified that sperm presence or absence on fluorescence microscopy can aid in the differentiation of fertile from infertile eggs to assist breeding managers in making prompt decisions for pair rearrangements. This protocol is currently used to manage several breeding pairs in San Diego Zoo global avian conservation programmes.
      PubDate: 2015-01-18T23:16:52-08:00
      DOI: 10.1093/conphys/cou060
      Issue No: Vol. 3, No. 1 (2015)
  • Effects of anthropogenic noise on endocrine and reproductive function in
           White's treefrog, Litoria caerulea

    • Authors: Kaiser, K; Devito, J, Jones, C. G, Marentes, A, Perez, R, Umeh, L, Weickum, R. M, McGovern, K. E, Wilson, E. H, Saltzman, W.
      Pages: cou061 - cou061
      Abstract: Urbanization is a major driver of ecological change and comes with a suite of habitat modifications, including alterations to the local temperature, precipitation, light and noise regimes. Although many recent studies have investigated the behavioural and ecological ramifications of urbanization, physiological work in this area has lagged. We tested the hypothesis that anthropogenic noise is a stressor for amphibians and that chronic exposure to such noise leads to reproductive suppression. In the laboratory, we exposed male White's treefrogs, Litoria caerulea, to conspecific chorus noise either alone or coupled with pre-recorded traffic noise nightly for 1 week. Frogs presented with anthropogenic noise had significantly higher circulating concentrations of corticosterone and significantly decreased sperm count and sperm viability than did control frogs. These results suggest that in addition to having behavioural and ecological effects, anthropogenic change might alter physiology and Darwinian fitness. Future work should integrate disparate fields such as behaviour, ecology and physiology to elucidate fully organisms’ responses to habitat change.
      PubDate: 2015-01-16T02:43:53-08:00
      DOI: 10.1093/conphys/cou061
      Issue No: Vol. 3, No. 1 (2015)
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