Yvette Williams | James Cook University (original) (raw)

Uploads

Papers by Yvette Williams

Journal of the American Mosquito Control Association, 2001

The ability of 2 freshwater fishes, eastern rainbow fish Melanotaenia splendida splendida and fly... more The ability of 2 freshwater fishes, eastern rainbow fish Melanotaenia splendida splendida and fly-specked hardyhead Craterocephalus stercusmuscarum stercusmuscarum, native to North Queensland to prey on immature Aedes aegypti was evaluated under laboratory conditions. The predation efficiency of the 2 species was compared to the exotic guppy, Poecilia reticulata, which is commonly used as a biological control agent of mosquito larvae. Of the 3 fish species tested, M. s. splendida was shown to be the most promising agent for the biological control of Ae. aegypti that breed in wells. Melanotaenia s. splendida consumed significantly greater numbers of immature Ae. aegypti than P. reticulata, irrespective of developmental stage or light conditions. Unlike C s. stercusmuscarum, M. s. splendida could be handled, transported, and kept in captivity for extended periods with negligible mortality. However, M. s. splendida was also an efficient predator of Litoria caerulea tadpoles, a species ...

Page 1. Ecological differences between rare and common species of microhylid frogs of the Wet Tro... more Page 1. Ecological differences between rare and common species of microhylid frogs of the Wet Tropics biogeographic region PhD thesis submitted by Yvette Marlene Williams (B.Sc. Hons) 2007 For the degree of Doctor of Philosophy School of Marine and Tropical Biology ...

Aust J Zool, 2004

Extensive abundance surveys of microhylid frogs across altitudinal gradients within the Wet Tropi... more Extensive abundance surveys of microhylid frogs across altitudinal gradients within the Wet Tropics rainforests of north-eastern Australia were undertaken. Detailed patterns of abundance were resolved for nine microhylid species exhibiting differing associations within the altitudinal gradient. The position of altitudinal range boundaries was found to be largely consistent with previous accounts in the literature, providing confidence in established limits to species distributions. Microhylid frogs, in particular those species restricted to mountaintops, are considered among other endemic rainforest vertebrates within the region to be one of the groups most immediately threatened by climate change. The combined results establish important baseline data for assessing the impacts of climate change, including altitudinal shifts in distribution and localised declines in abundance, on microhylid frogs in the region.

International Journal of Biometeorology, Jan 19, 2010

Species may circumvent or minimize some impacts resulting from climate change by utilizing microh... more Species may circumvent or minimize some impacts resulting from climate change by utilizing microhabitats that buffer against extreme events (e.g., heat waves). Boulder field habitats are considered to have functioned as important refugia for rainforest fauna during historical climate fluctuations. However, quantitative data on microhabitat buffering potential in these habitats is lacking. We characterized temperature buffering over small distances (i.e., depths) within an exposed and forested boulder field on a tropical mountain. We demonstrate that temperatures are cooler and become more stable at increasing depths within boulder fields. The magnitude of difference is most pronounced in exposed situations where temperatures within boulder fields can be as much as 10°C lower than near surface conditions. Our data provide a first step toward building models that more realistically predict exposure to heat stress for fauna that utilize rocky habitats.

Proceedings of the National Academy of Sciences, 2009

Species with narrow environmental niches typically have small geographic ranges. Small range size... more Species with narrow environmental niches typically have small geographic ranges. Small range size is, in turn, often associated with low local abundance. Together, these factors should mean that ecological specialists have very small total populations, putting them at high risk of extinction. But some specialized and geographically restricted species are ancient, and some ecological communities have high proportions of rare and specialized endemics. We studied niche characteristics and patterns of distribution and abundance of terrestrial vertebrates in the rainforests of the Australian Wet Tropics (AWT) to identify mechanisms by which rare species might resist extinction. We show that species with narrow environmental niches and small geographic ranges tend to have high and uniform local abundances. The compensation of geographic rarity by local abundance is exact, such that total population size in the rainforest vertebrates of the AWT is independent of environmental specialization. This effect would tend to help equalize extinction risk for specialists and generalists. Phylogenetic analysis suggests that environmental specialists have been gradually accumulating in this fauna, indicating that small range size/environmental specialization can be a successful trait as long as it is compensated for by demographic commonness. These results provide an explanation of how range-restricted specialists can persist for long periods, so that they now form a major component of high-diversity assemblages such as the AWT.

International Journal of Biometeorology, 2010

Species may circumvent or minimize some impacts resulting from climate change by utilizing microh... more Species may circumvent or minimize some impacts resulting from climate change by utilizing microhabitats that buffer against extreme events (e.g., heat waves). Boulder field habitats are considered to have functioned as important refugia for rainforest fauna during historical climate fluctuations. However, quantitative data on microhabitat buffering potential in these habitats is lacking. We characterized temperature buffering over small distances (i.e., depths) within an exposed and forested boulder field on a tropical mountain. We demonstrate that temperatures are cooler and become more stable at increasing depths within boulder fields. The magnitude of difference is most pronounced in exposed situations where temperatures within boulder fields can be as much as 10°C lower than near surface conditions. Our data provide a first step toward building models that more realistically predict exposure to heat stress for fauna that utilize rocky habitats.

Ecological Management & Restoration, 2014

Climatic Change, 2013

Severe impacts on biodiversity are predicted to arise from climate change. These impacts may not ... more Severe impacts on biodiversity are predicted to arise from climate change. These impacts may not be adequately addressed by conventional approaches to conservation. As a result, additional management actions are now being considered. However, there is currently limited guidance to help decision makers choose which set of actions (and in what order) is most appropriate for species that are considered to be vulnerable. Here, we provide a decision framework for the full complement of actions aimed at conserving species under climate change from ongoing conservation in existing refugia through various forms of mobility enhancement to ex situ conservation outside the natural environment. We explicitly recognize that allocation of conservation resources toward particular actions may be governed by factors such as the likelihood of success, cost and likely co-benefits to non-target species in addition to perceived vulnerability of individual species. As such, we use expert judgment of probable tradeoffs in resource allocation to inform the sequential evaluation of proposed management interventions.

Australian Zoologist, 2005

The patterns of composition and distribution of vertebrate fauna in Queensland's tropical savanna... more The patterns of composition and distribution of vertebrate fauna in Queensland's tropical savannas are poorly known. The sandstone landscapes of White Mountains National Park are considered to be significant for fauna given its geographical position on the Great Dividing Range. A survey at White Mountains National Park was undertaken in order to determine the species present, and place them in the context of the assemblages recorded within the Desert Uplands Bioregion. Standardised trapping and incidental data collection techniques were used and a total of 122 vertebrate fauna species (53 being new to the park) were identified. The fauna assemblage contains a mix of vertebrates with some affiliation to northeastern Queensland tropical savannas (e.g. Anomalopus gowi, Uperoleia lithomoda, Chaerephon jobensis), more mesic east coastal environments (e.g. Glaphyromorphus punctulatus, Planigale maculata, Rattus sordidus) and species distributed generally within and west of the Desert Uplands (e.g. Pseudomys desertor, Ctenotus rosarium, Gehyra variegata, Lerista wilkinsi).

We investigated the relationship between diet specialization and geographical range in Cophixalus... more We investigated the relationship between diet specialization and geographical range in Cophixalus, a genus of microhylid frogs from the Wet Tropics of northern Queensland, Australia. The geographical ranges of these species vary from a few square kilometres in species restricted to a single mountain top to the entire region for the widespread species. Although macroecological theory predicts that species with broad niches should have the largest geographical ranges, we found the opposite: geographically rare species were diet generalists and widespread species were diet specialists. We argue that this pattern is a product of extinction filtering, whereby geographically rare and therefore extinction-prone species are more likely to persist if they are diet generalists.

Journal of the American Mosquito Control Association, 2001

The ability of 2 freshwater fishes, eastern rainbow fish Melanotaenia splendida splendida and fly... more The ability of 2 freshwater fishes, eastern rainbow fish Melanotaenia splendida splendida and fly-specked hardyhead Craterocephalus stercusmuscarum stercusmuscarum, native to North Queensland to prey on immature Aedes aegypti was evaluated under laboratory conditions. The predation efficiency of the 2 species was compared to the exotic guppy, Poecilia reticulata, which is commonly used as a biological control agent of mosquito larvae. Of the 3 fish species tested, M. s. splendida was shown to be the most promising agent for the biological control of Ae. aegypti that breed in wells. Melanotaenia s. splendida consumed significantly greater numbers of immature Ae. aegypti than P. reticulata, irrespective of developmental stage or light conditions. Unlike C s. stercusmuscarum, M. s. splendida could be handled, transported, and kept in captivity for extended periods with negligible mortality. However, M. s. splendida was also an efficient predator of Litoria caerulea tadpoles, a species ...

Page 1. Ecological differences between rare and common species of microhylid frogs of the Wet Tro... more Page 1. Ecological differences between rare and common species of microhylid frogs of the Wet Tropics biogeographic region PhD thesis submitted by Yvette Marlene Williams (B.Sc. Hons) 2007 For the degree of Doctor of Philosophy School of Marine and Tropical Biology ...

Aust J Zool, 2004

Extensive abundance surveys of microhylid frogs across altitudinal gradients within the Wet Tropi... more Extensive abundance surveys of microhylid frogs across altitudinal gradients within the Wet Tropics rainforests of north-eastern Australia were undertaken. Detailed patterns of abundance were resolved for nine microhylid species exhibiting differing associations within the altitudinal gradient. The position of altitudinal range boundaries was found to be largely consistent with previous accounts in the literature, providing confidence in established limits to species distributions. Microhylid frogs, in particular those species restricted to mountaintops, are considered among other endemic rainforest vertebrates within the region to be one of the groups most immediately threatened by climate change. The combined results establish important baseline data for assessing the impacts of climate change, including altitudinal shifts in distribution and localised declines in abundance, on microhylid frogs in the region.

International Journal of Biometeorology, Jan 19, 2010

Species may circumvent or minimize some impacts resulting from climate change by utilizing microh... more Species may circumvent or minimize some impacts resulting from climate change by utilizing microhabitats that buffer against extreme events (e.g., heat waves). Boulder field habitats are considered to have functioned as important refugia for rainforest fauna during historical climate fluctuations. However, quantitative data on microhabitat buffering potential in these habitats is lacking. We characterized temperature buffering over small distances (i.e., depths) within an exposed and forested boulder field on a tropical mountain. We demonstrate that temperatures are cooler and become more stable at increasing depths within boulder fields. The magnitude of difference is most pronounced in exposed situations where temperatures within boulder fields can be as much as 10°C lower than near surface conditions. Our data provide a first step toward building models that more realistically predict exposure to heat stress for fauna that utilize rocky habitats.

Proceedings of the National Academy of Sciences, 2009

Species with narrow environmental niches typically have small geographic ranges. Small range size... more Species with narrow environmental niches typically have small geographic ranges. Small range size is, in turn, often associated with low local abundance. Together, these factors should mean that ecological specialists have very small total populations, putting them at high risk of extinction. But some specialized and geographically restricted species are ancient, and some ecological communities have high proportions of rare and specialized endemics. We studied niche characteristics and patterns of distribution and abundance of terrestrial vertebrates in the rainforests of the Australian Wet Tropics (AWT) to identify mechanisms by which rare species might resist extinction. We show that species with narrow environmental niches and small geographic ranges tend to have high and uniform local abundances. The compensation of geographic rarity by local abundance is exact, such that total population size in the rainforest vertebrates of the AWT is independent of environmental specialization. This effect would tend to help equalize extinction risk for specialists and generalists. Phylogenetic analysis suggests that environmental specialists have been gradually accumulating in this fauna, indicating that small range size/environmental specialization can be a successful trait as long as it is compensated for by demographic commonness. These results provide an explanation of how range-restricted specialists can persist for long periods, so that they now form a major component of high-diversity assemblages such as the AWT.

International Journal of Biometeorology, 2010

Species may circumvent or minimize some impacts resulting from climate change by utilizing microh... more Species may circumvent or minimize some impacts resulting from climate change by utilizing microhabitats that buffer against extreme events (e.g., heat waves). Boulder field habitats are considered to have functioned as important refugia for rainforest fauna during historical climate fluctuations. However, quantitative data on microhabitat buffering potential in these habitats is lacking. We characterized temperature buffering over small distances (i.e., depths) within an exposed and forested boulder field on a tropical mountain. We demonstrate that temperatures are cooler and become more stable at increasing depths within boulder fields. The magnitude of difference is most pronounced in exposed situations where temperatures within boulder fields can be as much as 10°C lower than near surface conditions. Our data provide a first step toward building models that more realistically predict exposure to heat stress for fauna that utilize rocky habitats.

Ecological Management & Restoration, 2014

Climatic Change, 2013

Severe impacts on biodiversity are predicted to arise from climate change. These impacts may not ... more Severe impacts on biodiversity are predicted to arise from climate change. These impacts may not be adequately addressed by conventional approaches to conservation. As a result, additional management actions are now being considered. However, there is currently limited guidance to help decision makers choose which set of actions (and in what order) is most appropriate for species that are considered to be vulnerable. Here, we provide a decision framework for the full complement of actions aimed at conserving species under climate change from ongoing conservation in existing refugia through various forms of mobility enhancement to ex situ conservation outside the natural environment. We explicitly recognize that allocation of conservation resources toward particular actions may be governed by factors such as the likelihood of success, cost and likely co-benefits to non-target species in addition to perceived vulnerability of individual species. As such, we use expert judgment of probable tradeoffs in resource allocation to inform the sequential evaluation of proposed management interventions.

Australian Zoologist, 2005

The patterns of composition and distribution of vertebrate fauna in Queensland's tropical savanna... more The patterns of composition and distribution of vertebrate fauna in Queensland's tropical savannas are poorly known. The sandstone landscapes of White Mountains National Park are considered to be significant for fauna given its geographical position on the Great Dividing Range. A survey at White Mountains National Park was undertaken in order to determine the species present, and place them in the context of the assemblages recorded within the Desert Uplands Bioregion. Standardised trapping and incidental data collection techniques were used and a total of 122 vertebrate fauna species (53 being new to the park) were identified. The fauna assemblage contains a mix of vertebrates with some affiliation to northeastern Queensland tropical savannas (e.g. Anomalopus gowi, Uperoleia lithomoda, Chaerephon jobensis), more mesic east coastal environments (e.g. Glaphyromorphus punctulatus, Planigale maculata, Rattus sordidus) and species distributed generally within and west of the Desert Uplands (e.g. Pseudomys desertor, Ctenotus rosarium, Gehyra variegata, Lerista wilkinsi).

We investigated the relationship between diet specialization and geographical range in Cophixalus... more We investigated the relationship between diet specialization and geographical range in Cophixalus, a genus of microhylid frogs from the Wet Tropics of northern Queensland, Australia. The geographical ranges of these species vary from a few square kilometres in species restricted to a single mountain top to the entire region for the widespread species. Although macroecological theory predicts that species with broad niches should have the largest geographical ranges, we found the opposite: geographically rare species were diet generalists and widespread species were diet specialists. We argue that this pattern is a product of extinction filtering, whereby geographically rare and therefore extinction-prone species are more likely to persist if they are diet generalists.