Can supervise: YES
Ecological Impacts of Climate Change
Tang, J, Wang, J, Fang, Q, Dayananda, B, Yu, Q, Zhao, P, Yin, H & Pan, X 2019, 'Identifying agronomic options for better potato production and conserving water resources in the agro-pastoral ecotone in North China', Agricultural and Forest Meteorology, vol. 272-273, pp. 91-101.View/Download from: UTS OPUS or Publisher's site
© 2019 Elsevier B.V. Potato is a main food crop in the agro-pastoral ecotone (APE) of North China, but its yield is low and highly variable. Agronomic managements, such as irrigation, fertilization and intensive cropping systems, has been used for increasing potato yield but resulted in negative environmental sequences (e.g., soil dryness and groundwater table decline) in such arid and semi-arid regions. This study aims to quantify the agronomic options for better potato production and groundwater conservations based on field experiments together with APSIM-Potato model. The long-term simulated crop yield, economic income and environmental impact (surface soil water content and groundwater table) were analyzed for the different cropping systems of potato (continuous planting, CP; alternating planting and fallowing, APF; long-term continuous fallowing, LF) and irrigation scheduling (rainfed and one-four irrigations). The calibrated APSIM-Potato performed well in simulating the responses of soil water dynamics, leaf area index (LAI), biomass, evapotranspiration (ET) and yield of potato to different irrigation treatments. Long-term (1981–2010) simulated potato yield could be increased by 43.4–90.2% from rainfed yield if irrigation was applied from 60 to 240 mm and the yield gap between the potential and rainfed yields could be narrowed by 41.5–85.9%. Across the APE, CP with four irrigations (240 mm) produced the maximum income of 18,445 Yuan·ha−1 while WUE was the highest for both CP and APF with two irrigations (120 mm). However, such irrigation amounts would decrease the groundwater table by 4.1–42 m across the APE during this period. Rainfed CP could enhance the groundwater table by 0–3 m but decrease available soil water content in 1 m depth by 15.5 mm per decade from 1981 to 2010. Rainfed APF and LF increase available soil water content in 1 m depth by 2–79 mm and 100–143 mm respectively. The study suggested that CP would decrease the soil moisture significantl...
Bezeng, BS, Tesfamichael, SG & Dayananda, B 2018, 'Predicting the effect of climate change on a range-restricted lizard in southeastern Australia.', Current Zoology, vol. 64, no. 2, pp. 165-171.View/Download from: Publisher's site
Climate change is ranked as one of the most severe threats to global biodiversity. This global phenomenon is particularly true for reptiles whose biology and ecology are closely linked to climate. In this study, we used over 1,300 independent occurrence points and different climate change emission scenarios to evaluate the potential risk of changing climatic conditions on the current and future potential distribution of a rock-dwelling lizard; the velvet gecko. Furthermore, we investigated if the current extent of protected area networks in Australia captures the full range distribution of this species currently and in the future. Our results show that climate change projections for the year 2075 have the potential to alter the distribution of the velvet gecko in southeastern Australia. Specifically, climate change may favor the range expansion of this species to encompass more suitable habitats. The trend of range expansion was qualitatively similar across the different climate change scenarios used. Additionally, we observed that the current network of protected areas in southeast Australia does not fully account for the full range distribution of this species currently and in the future. Ongoing climate change may profoundly affect the potential range distribution of the velvet gecko population. Therefore, the restricted habitat of the velvet geckos should be the focus of intensive pre-emptive management efforts. This management prioritization should be extended to encompass the increases in suitable habitats observed in this study in order to maximize the microhabitats available for the survival of this species.
Dayananda, B, Ibargüengoytía, N, Whiting, MJ & Webb, JK 2017, 'Effects of pregnancy on body temperature and locomotor performance of velvet geckos.', Journal of Thermal Biology, vol. 65, pp. 64-68.View/Download from: UTS OPUS or Publisher's site
Pregnancy is a challenging period for egg laying squamates. Carrying eggs can encumber females and decrease their locomotor performance, potentially increasing their risk of predation. Pregnant females can potentially reduce this handicap by selecting higher temperatures to increase their sprint speed and ability to escape from predators, or to speed up embryonic development and reduce the period during which they are burdened with eggs ('selfish mother' hypothesis). Alternatively, females might select more stable body temperatures during pregnancy to enhance offspring fitness ('maternal manipulation hypothesis'), even if the maintenance of such temperatures compromises a female's locomotor performance. We investigated whether pregnancy affects the preferred body temperatures and locomotor performance of female velvet geckos Amalosia lesueurii. We measured running speed of females during late pregnancy, and one week after they laid eggs at four temperatures (20°, 25°, 30° and 35°C). Preferred body temperatures of females were measured in a cost-free thermal gradient during late pregnancy and one week after egg-laying. Females selected higher and more stable set-point temperatures when they were pregnant (mean =29.0°C, Tset =27.8-30.5°C) than when they were non-pregnant (mean =26.2°C, Tset =23.7-28.7°C). Pregnancy was also associated with impaired performance; females sprinted more slowly at all four test temperatures when burdened with eggs. Although females selected higher body temperatures during late pregnancy, this increase in temperature did not compensate for their impaired running performance. Hence, our results suggest that females select higher temperatures during pregnancy to speed up embryogenesis and reduce the period during which they have reduced performance. This strategy may decrease a female's probability of encountering predatory snakes that use the same microhabitats for thermoregulation. Selection of stable temperatures by pregnant females may...
Penfold, S, Dayananda, B & Webb, JK 2017, 'Chemical cues influence retreat-site selection by flat rock spiders', Behaviour, vol. 154, no. 2, pp. 149-161.View/Download from: UTS OPUS or Publisher's site
© 2017 Copyright 2017 by Koninklijke Brill NV, Leiden, The Netherlands. Many animals use chemical cues to detect conspecifics and predators. On sandstone outcrops, flat rock spiders Morebilus plagusius and Polyrachis ants use sun-exposed rocks as nest sites, and defend rocks from intruders. We investigated whether chemical cues influenced retreat-site selection by spiders. In the field, spiders showed significant avoidance of rocks used by ants. In laboratory trials, we gave spiders the choice between conspecific-scented and unscented refuges, and ant-scented and unscented refuges. In conspecific scent trials, spiders showed no avoidance of spider scented refuges during the night, but significantly more spiders chose unscented refuges as their diurnal retreat-site. In ant scent trials, spiders made more visits to unscented refuges than ant-scented refuges during the night, and significantly more spiders chose unscented refuges as their diurnal retreat site. Our results demonstrate that spiders can detect chemical cues from ants and conspecifics, and that such cues influence retreat-site selection.
Dayananda, B. & Webb, JK 2017, 'Incubation under climate warming affects learning ability and survival in hatchling lizards', Biology Letters, vol. 13, no. 3, pp. 1-4.View/Download from: UTS OPUS or Publisher's site
Despite compelling evidence for substantial individual differences in cognitive performance, it is unclear whether cognitive ability influences fitness of wild animals. In many animals, environmental stressors experienced in utero can produce substantial variation in the cognitive abilities of offspring. In reptiles, incubation temperatures experienced by embryos can influence hatchling brain function and learning ability. Under climate warming, the eggs of some lizard species may experience higher temperatures, which could affect the cognitive abilities of hatchlings. Whether such changes in cognitive abilities influence the survival of hatchlings is unknown. To determine whether incubation-induced changes in spatial learning ability affect hatchling survival, we incubated velvet gecko, Amalosia lesueurii, eggs using two fluctuating temperature regimes to mimic current (cold) versus future (hot) nest temperatures. We measured the spatial learning ability of hatchlings from each treatment, and released individually marked animals at two field sites in southeastern Australia. Hatchlings from hot-incubated eggs were slower learners than hatchlings from cold-incubated eggs. Survival analyses revealed that hatchlings with higher learning scores had higher survival than hatchlings with poor learning scores. Our results show that incubation temperature affects spatial learning ability in hatchling lizards, and that such changes can influence the survival of hatchlings in the wild.
Dayananda, B, Murray, BR & Webb, JK 2017, 'Hotter nests produce hatchling lizards with lower thermal tolerance.', The Journal of Experimental Biology, vol. 220, pp. 2159-2165.View/Download from: UTS OPUS or Publisher's site
In many regions, the frequency and duration of summer heatwaves is predicted to increase in future. Hotter summers could result in higher temperatures inside lizard nests, potentially exposing embryos to thermally stressful conditions during development. Potentially, developmentally plastic shifts in thermal tolerance could allow lizards to adapt to climate warming. To determine how higher nest temperatures affect the thermal tolerance of hatchling geckos, we incubated eggs of the rock-dwelling velvet gecko, Amalosia lesueurii, at two fluctuating temperature regimes to mimic current nest temperatures (mean 23.2°C, range 10-33°C, 'cold') and future nest temperatures (mean 27.0°C, range 14-37°C, 'hot'). Hatchlings from the hot incubation group hatched 27 days earlier and had a lower critical thermal maximum (CTmax 38.7°C) and a higher critical thermal minimum (CTmin 6.2°C) than hatchlings from cold incubation group (40.2 and 5.7°C, respectively). In the field, hatchlings typically settle under rocks near communal nests. During the hatching period, rock temperatures ranged from 13 to 59°C, and regularly exceeded the CTmax of both hot- and cold-incubated hatchlings. Because rock temperatures were so high, the heat tolerance of lizards had little effect on their ability to exploit rocks as retreat sites. Instead, the timing of hatching dictated whether lizards could exploit rocks as retreat sites; that is, cold-incubated lizards that hatched later encountered less thermally stressful environments than earlier hatching hot-incubated lizards. In conclusion, we found no evidence that CTmax can shift upwards in response to higher incubation temperatures, suggesting that hotter summers may increase the vulnerability of lizards to climate warming.
Dayananda, B, Penfold, S & Webb, JK 2017, 'The effects of incubation temperature on locomotor performance, growth and survival in hatchling velvet geckos', Journal of Zoology, vol. 303, no. 1, pp. 46-53.View/Download from: UTS OPUS or Publisher's site
© 2017 The Zoological Society of London The thermal environment that lizard eggs experience during incubation can affect the size, shape and performance of hatchlings. Summer heatwaves are predicted to increase in frequency and duration in the future, and could produce higher temperatures inside lizard nests. Increase in nest temperatures may influence offspring sex, body size, growth and locomotor performance, which in turn can affect fitness. We investigated whether incubation temperatures influenced the locomotor performance of hatchlings of the velvet gecko (Amalosia lesueurii), a nocturnal gecko that lays eggs in communal nests inside rock crevices. We incubated eggs at two fluctuating temperature regimes that mimicked current nest temperatures (mean = 23.2°C, range 10–33°C, 'current') and predicted future nest temperatures (mean = 27.0°C, 14–37°C, 'future'). We measured the locomotor performance of hatchlings at four temperatures (20, 25, 30 and 35°C), and released them at two field sites (Nowra and Dharawal National Park, 'DNP') to estimate their growth and survival over 10 months. Hot-incubated hatchlings were smaller, and ran more slowly than current-incubated hatchlings at all four test temperatures. Incubation temperature did not affect the growth rates of lizards from Nowra, but at DNP, hot-incubated lizards grew more slowly than current-incubated lizards. Survival analyses revealed that future-incubated hatchlings had lower survival than current-incubation hatchlings over 10 months of life, but selection on hatchling traits differed between study sites. For hatchlings from DNP, there was evidence for directional selection on body mass, but little support for selection on SVL or speed. At Nowra, there was equivalent evidence for selection on mass, SVL and speed. These results demonstrate that incubation induced differences in morphology and locomotor performance can influence the survival of hatchlings. In the absence of maternal plasticity in nesting...
Dayananda, B, Gray, S, Pike, D & Webb, JK 2016, 'Communal nesting under climate change: Fitness consequences of higher incubation temperatures for a nocturnal lizard', Global Change Biology, vol. 22, no. 7, pp. 2405-2414.View/Download from: UTS OPUS or Publisher's site
Communal nesting lizards may be vulnerable to climate warming, particularly if air temperatures regulate nest temperatures. In southeastern Australia, velvet geckos Oedura lesueurii lay eggs communally inside rock crevices. We investigated whether increases in air temperatures could elevate nest temperatures, and if so, how this could influence hatching phenotypes, survival, and population dynamics. In natural nests, maximum daily air temperature influenced mean and maximum daily nest temperatures, implying that nest temperatures will increase under climate warming. To determine whether hotter nests influence hatchling phenotypes, we incubated eggs under two fluctuating temperature regimes to mimic current 'cold' nests (mean = 23.2 °C, range 10-33 °C) and future 'hot' nests (27.0 °C, 14-37 °C). 'Hot' incubation temperatures produced smaller hatchlings than did cold temperature incubation. We released individually marked hatchlings into the wild in 2014 and 2015, and monitored their survival over 10 months. In 2014 and 2015, hot-incubated hatchlings had higher annual mortality (99%, 97%) than cold-incubated (11%, 58%) or wild-born hatchlings (78%, 22%). To determine future trajectories of velvet gecko populations under climate warming, we ran population viability analyses in Vortex and varied annual rates of hatchling mortality within the range 78- 96%. Hatchling mortality strongly influenced the probability of extinction and the mean time to extinction. When hatchling mortality was >86%, populations had a higher probability of extinction (PE: range 0.52- 1.0) with mean times to extinction of 18-44 years. Whether future changes in hatchling survival translate into reduced population viability will depend on the ability of females to modify their nest-site choices. Over the period 1992-2015, females used the same communal nests annually, suggesting that there may be little plasticity in maternal nest-site selection. The impacts of climate change may therefore be es...
Gabadage, DE, Botejue, WMS, Surasinghe, TD, Bahir, MM, Madawala, MB, Dayananda, B, Weeratunga, VU & Karunarathna, DMSS 2015, 'Avifaunal diversity in the peripheral areas of the Maduruoya National Park in Sri Lanka: With conservation and management implications', Journal of Asia-Pacific Biodiversity, vol. 8, no. 2, pp. 121-132.View/Download from: Publisher's site
Dayananda, B 2016, 'Will early hatchlings toast?', The 8th World Congress of Herpetology, China.
Dayananda, B 2016, 'Will hotter nests cause lizard extinctions?', The 8th World Congress of Herpetology, China.
Dayananda, B 2016, 'Effects of climate change on cognitive ability of hatchling lizards', 16th International Behavioral Ecology Congress (ISBE 2016), The University of Exeter, UK.
Dayananda, B 2015, 'Circadian rhythm in locomotor performance of nocturnal lizards', International Ethological Conference – Behaviour 2015, Cairns, Australia.
Dayananda, B 2015, 'The interplay between environmental temperatures and locomotor performance of lizards and their preferred body temperatures during reproduction period', 52nd Annual Meeting of the Association for Tropical Biology and Conversation (ATBC 2015), Annual Meeting of the Association for Tropical Biology and Conversation, Honolulu, Hawaii.
Dayananda, B 2015, 'Predicted increases in nest temperatures affect the survival of hatchling velvet geckos', 5th International Wildlife Management Congress -IWMC2015, International Wildlife Management Congress, Sapporo, Japan.
Dayananda, B 2014, 'Decreased locomotor performance as a cost of reproduction in the velvet gecko, Oedura lesueurii: interactive effects of time, reproductive status and temperature on locomotion', International Society for Behavioral Ecology Conference-ISBE 2014, International Society for Behavioral Ecology Conference, New York, New York, USA.