Ross Alford

James Cook University, Science and Engineering, Emeritus

Followers

Following

Co-authors

Public Views

M.Sc, Florida, 1981
Ph.D., Duke, 1986
Lecturer, James Cook University, 1986
Senior Lecturer, JCU, 1992
Associate Professor, JCU, 1996
Professor (personal chair), JCU, 2007
Professor Emeritus, JCU, 2016

Population and community ecologist, with strong interests in conservation biology, reptile and amphibian biology and evolution, and host-pathogen ecology, particularly as related to global amphibian declines.

less

C. Michael Hall

University of Canterbury/Te Whare Wānanga o Waitaha

Julian D Reynolds

Trinity College Dublin

Jayjit Majumdar

University of Kalyani

John Clark

Loyola University New Orleans

Eve Emshwiller

University of Wisconsin-Madison

David Seamon

Kansas State University

Armando Marques-Guedes

UNL - New University of Lisbon

Peter Doran

Queen's University Belfast

Marilyn Sobel

Drexel University

Viacheslav Kuleshov

Stockholm University

InterestsView All (9)

Uploads

Papers by Ross Alford

The history of amphibian declines in Australia

Bleak future for amphibians

Nature, Dec 1, 2011

[Extract] The major threats to amphibian species include pandemic disease and changes in climate ... more

Host thermoregulatory constraints predict growth of an amphibian chytrid pathogen (Batrachochytrium dendrobatidis)

Journal of Thermal Biology, 2020

Download

Infection intensity and sampling locality affectBatrachochytrium dendrobatidisdistribution among body regions on green-eyed tree frogsLitoria genimaculata

Diseases of Aquatic Organisms, Sep 24, 2008

Batrachochytrium dendrobatidis (Bd) causes chytridiomycosis, which has caused devastating amphibi... more Batrachochytrium dendrobatidis (Bd) causes chytridiomycosis, which has caused devastating amphibian population declines. Little is known about the biology of Bd on hosts, and techniques for diagnosing it on living and preserved animals are still evolving. We investigated the spatial distribution of Bd on the integument of naturally infected Australian hylid frogs Litoria genimaculata at 4 rain forest localities in northern Queensland, Australia. We collected 555 samples by swabbing 111 individuals on 5 regions of the body (back, abdomen, legs, forefeet and hindfeet). Numbers of zoospore equivalents on each body region were quantified using a real-time TaqMan PCR assay. The intensity of infection differed significantly among body regions and this pattern of differences differed among sampling localities. The lightest infections were usually centered on the abdomen, while heavier infections were concentrated on the legs and feet. The back was always either lightly infected or uninfected. Many frogs with light infections had positive PCR results only for the abdomen or the legs. We compared swabs taken from the legs and abdomen and found that they provided similar sensitivity to detect infections, but using both regions together led to greater sensitivity than either region alone. Because swabbing may transfer zoospores from infected to uninfected regions within individuals, we suggest that the best procedure for all species is to employ separate swabs for each body region. If that cannot be done, swabbing patterns that minimize potential harm should be determined for each species, and possibly each class of individuals (e.g. males, females, juveniles) within species, by examining the distribution of infection among body parts in naturally infected individuals.

Download

Declines and the Global Status of Amphibians

CRC Press eBooks, Jun 2, 2010

The global diversity and status of both amphibians and reptiles at the end of the 20th century we... more The global diversity and status of both amphibians and reptiles at the end of the 20th century were described in thorough detail in the previous edition of the current volume (McDiarmid and Mitchell 2000). During the 1990s, however, it became clear that the diversity and status of amphibians were changing rapidly, with substantial declines in amphibian populations in many regions (Alford and Richards1999). There has also been widespread concern regarding possible increases in the prevalence of developmental abnormalities and malformations in amphibians (Johnson et al. 2003). Great advances have been made in understanding these problems since 1999. This chapter concentrates on defining the problems, illustrating and interpreting our understanding of their causes, and developing ideas regarding how the problems can be managed.

Effects of Season and Weather on Calling in the Australian Microhylid Frogs Austrochaperina Robusta and Cophixalus Ornatus

Herpetologica, Dec 1, 2005

It is sometimes perceived that the cues affecting chorusing behavior in frogs are simple combinat... more It is sometimes perceived that the cues affecting chorusing behavior in frogs are simple combinations of weather variables, and that closely related or sympatric species should respond to these cues in similar ways. We investigated these ideas by examining chorusing behavior in two species of tropical Australian microhylid frogs, Austrochaperina robusta and Cophixalus ornatus. Both species have small adult body sizes, are terrestrial breeding, direct-developers, and extensively co-occur in the Australian Wet Tropics. We used timed tape recorders to monitor calling activity over two breeding seasons (October to March) during 1995-96 and 2001-02. Calling activity was recorded at three times each night at seven locations along a 550 m transect. In the 2001-2002 seasons, dataloggers recorded temperature, humidity, and rainfall, and we calculated moon phase each night. Individuals of C. ornatus called more times per minute than individuals of A. robusta, and called at much more consistent levels across nights, in a seasonal pattern that closely followed a quadratic curve in both seasons. Calling activity by A. robusta males could occur at any level on any night of the breeding season, and varied greatly among nights. Principal components analyses for the 2001-02 data showed that 78.1% of variation in A. robusta calling activity could be due to factors common to the entire transect, while such factors could account for 62.8% of the variation in calling by C. ornatus. This result suggests that weather influences calling activity of A. robusta males more than of C. ornatus males. Canonical discriminant function analyses and partial rank correlations of the relationships between environmental variables and calling activity over the season indicated that initiation of calling in A. robusta males was strongly affected by rainfall, and continuation of calling by rainfall and humidity. Calling initiation in C. ornatus males was less correlated with weather variables, and appeared most strongly affected by humidity. Calling levels within species were correlated across the three recording times each night, but much less strongly than would be expected if caused by responses to weather. Calling activity also was correlated between species at each time of night, and a substantial proportion of this correlation did not appear to be caused by common responses to the weather variables we measured. We suggest that in both species weather conditions affect the probability of initiation of calling activity, and that initiation and continuation of calling are probably also affected by intraspecific and perhaps interspecific social facilitation.

Download

Status and priority conservation actions for Australian frog species

Biological Conservation, Jul 1, 2020

Abstract Coherent, multi-species conservation strategies rely on up-to-date assessments of extinc... more Abstract Coherent, multi-species conservation strategies rely on up-to-date assessments of extinction risk, and prioritising and implementing well-founded management and research actions. Using IUCN criteria and methods, we reassessed the conservation status of all 243 Australian frog species. We also identified key threats and associated potential management actions. We subsequently scored the relative value, feasibility and current levels of implementation of all management and research actions for threatened and Data Deficient species. These scores were then used to rank the relative priority of management and research actions, identifying the highest priority actions for reducing extinction risk for Australia's frogs. Our revised assessment identified 45 threatened frog species in Australia, a 10% reduction from the 2004 assessment. However, the number of species assessed as Extinct increased by two, and four species were added to the Critically Endangered list. Improvements in conservation status for some species resulted from better knowledge and natural population stabilisation or recovery following disease impacts, rather than as a consequence of management. Improved knowledge has also resulted in a reduction of Data Deficient species from ten to eight. We found substantial reductions in species extinction risk may be achievable by implementing a relatively discrete set of well-targeted management and research actions. Given its simple and dynamic nature, our method can be regularly updated with new information, and can also be applied at different geographic scales. Our prioritisation will enable improved allocation of limited resources to maximise conservation outcomes for Australian frogs.

Movement and Microhabitat Use of a Terrestrial Amphibian (Bufo marinus) on a Tropical Island: Seasonal Variation and Environmental Correlates

Journal of Herpetology, Jun 1, 1999

... 6.0 g which represented 7% of the body weight of the smallest animal spooled (85.0 g). On ave... more

Priority Effects in Experimental Pond Communities: Competition between Bufo and Rana

Ecology, Aug 1, 1985

... Abstract . Full Text . PDF (691 KB). Scott T. Woody, Anthony R. Ives, Erik V. Nordheim, John ... more

Isolated frogs in a crowded world: Effects of human-caused habitat loss on frog heterozygosity and fluctuating asymmetry

Biological Conservation, Mar 1, 2016

It is important to develop research methods that will detect deterioration in population health b... more It is important to develop research methods that will detect deterioration in population health before severe declines occur. Amphibian population declines are widespread; the main causes are anthropogenic and include habitat fragmentation due to agriculture, mining, fires, and urban development. Brazil is the richest country in species of amphibians, and the Brazilian regions with the greatest amphibian diversity are experiencing relatively high rates of habitat destruction. We tested the use of measurements of fluctuating asymmetry (FA) taken on adult frogs, as well as heterozygosity estimates in frog populations, to detect anthropogenic stress. We hypothesized that greater human occupancy in the landscape might result in more stressful conditions for amphibians, which would be reflected in high FA levels and/or reduced heterozygosity. We conducted this study at the Espinhaco mountain range in southeastern Brazil, using an endemic species (Bokermannohyla saxicola, Hylidae) as a model. We found that adult frog FA levels differed among localities but did not find significant correlations between human modification of the landscape and FA levels. In the subsample of localities for which we had genetic data, heterozygosity was significantly inversely correlated with FA in adult frogs, and heterozygosity decreased with increasing human occupancy in the landscape, except for populations with marginal distribution within the species range that already had very low heterozygosity. Our major finding was that reduced heterozygosity may be caused by population isolation resulting from human occupancy (among other causes) and is correlated with increased fluctuating asymmetry, so that either may indicate higher levels of stress in populations of B. saxicola.

Structure and dynamics of a rainforest frog (Litoria genimaculata) population in northern Queensland

Australian Journal of Zoology, 2005

We studied a population of the rainforest frog Litoria genimaculata over a 7-year period at Birth... more We studied a population of the rainforest frog Litoria genimaculata over a 7-year period at Birthday Creek, an upland rainforest stream in northern Queensland. Estimated population size on a 60-m transect fluctuated seasonally, decreasing to zero during most winters and reaching a maximum of over 130 during most warmer spring and summer months with an influx of young adult males. Summer population estimates were much smaller during 1990–93, coinciding with the disappearance of two sympatric species. However the L. genimaculata population subsequently recovered to pre-‘decline’ levels. Females were rarely captured along the stream so the operational sex ratio of adult frogs was strongly biased in favour of males (overall sex ratio 1 : 0.04). Sexual dimorphism in this species is extreme. The mean weight of gravid females (23.35 g) was nearly five times that of males (4.68 g) and the ratio of female SVL to male SVL was 1.65. Reproductive and fat-body condition changed seasonally, with males reaching peak reproductive condition in late spring and summer when population densities were greatest. Our data suggest that Litoria genimaculata uses Birthday Creek largely or exclusively as a reproductive habitat. The extent to which this species uses habitats away from stream environments remains to be determined.

Techniques for tracking amphibians: The effects of tag attachment, and harmonic direction finding versus radio telemetry

Amphibia-reptilia, 2007

To gain information on the microhabitat use, home range and movement of a species, it is often ne... more To gain information on the microhabitat use, home range and movement of a species, it is often necessary to remotely track individuals in the field. Radio telemetry is commonly used to track amphibians, but can only be used on relatively large individuals. Harmonic direction finding can be used to track smaller animals, but its effectiveness has not been fully evaluated. Tag attachment can alter the behaviour of amphibians, suggesting that data obtained using either technique may be unreliable. We investigated the effects of external tag attachment on behaviour in the laboratory by observing 12 frogs for five nights before and five nights after tag attachment, allowing one night to recover from handling. Tag attachment did not affect distance moved or number of times moved, indicating that the effects of tag attachment are unlikely to persist after the first night following attachment. We then compared harmonic direction finding and radio-telemetry using data collected in the field. We fitted rainforest stream frogs of three species with tags of either type, located them diurnally and nocturnally for approximately two weeks, and compared movement parameters between techniques. In the field, we obtained fewer fixes on frogs using harmonic direction finding, but measures of movement and habitat use did not differ significantly between techniques. Because radio telemetry makes it possible to locate animals more consistently, it should be preferred for animals large enough to carry radio tags. If harmonic direction finding is necessary, it can produce reliable data, particularly for relatively sedentary species.

Download

The Ontogeny of Fluctuating Asymmetry

The American Naturalist, Jun 1, 2003

We tested seven hypotheses regarding the mechanisms by which fluctuating asymmetry (FA) originate... more We tested seven hypotheses regarding the mechanisms by which fluctuating asymmetry (FA) originates. We did this by analyzing data on four bilateral characters measured repeatedly during the development of individual domestic fowl. Immediately posthatching, there was substantial directional asymmetry, which rapidly decreased. We detected FA at significant levels in all characters in the majority of our measurements over the remainder of development. We also examined the effects of known environmental stressors (food and density stress) on levels of FA. At the levels we examined, changes in these stressors did not alter the degree of asymmetry we found in fowl. Time series of asymmetry for individuals did not exhibit regular oscillations, as much of the relevant literature predicts. Asymmetry levels reflected the combined effects of developmental noise, which was random in degree and direction, and feedback processes, which decreased asymmetry by altering growth rates on both sides of the body. Our findings best fit the predictions of the residual asymmetry and compensatory growth hypotheses, which suggest that levels of asymmetry reflect only recent growth history.

Download

Context-dependent symbioses and their potential roles in wildlife diseases

Proceedings of The Royal Society B: Biological Sciences, Jan 11, 2012

It is well known in ecology, evolution and medicine that both the nature (commensal, parasitic an... more It is well known in ecology, evolution and medicine that both the nature (commensal, parasitic and mutualistic) and outcome (symbiont fitness, survival) of symbiotic interactions are often contextdependent. Less is known about the importance of context-dependence in symbioses involved in wildlife disease. We review variable symbioses, and use the amphibian disease chytridiomycosis to demonstrate how understanding context-dependence can improve the understanding and management of wildlife diseases. In chytridiomycosis, the host-pathogen interaction is context-dependent; it is strongly affected by environmental temperature. Skin bacteria can also modify the interaction; some bacteria reduce amphibians' susceptibility to chytridiomycosis. Augmentation of protective microbes is being considered as a possible management tool, but informed application of bioaugmentation requires understanding of how the interactions between host, beneficial bacteria and pathogen depend upon environmental context. The community-level response of the amphibian skin microbiota to environmental conditions may explain the relatively narrow range of environmental conditions in which past declines have occurred. Environmental context affects virulence and the protection provided by mutualists in other host-pathogen systems, including threatened bats and corals. Increased focus on context-dependence in interactions between wildlife and their symbionts is likely to be crucial to the future investigation and management of emerging diseases of wildlife.

Download

Priority Effects in Experimental Pond Communities: Responses of Hyla to Bufo and Rana

Ecology, Aug 1, 1985

... Abstract . Full Text . PDF (691 KB). Scott T. Woody, Anthony R. Ives, Erik V. Nordheim, John ... more

Amphibians, Biodiversity of

Modern amphibians are an ancient, diverse, and successful group, with almost 7000 species recogni... more Modern amphibians are an ancient, diverse, and successful group, with almost 7000 species recognized and many yet to be described. Many species have complex life cycles, allowing them to use unstable habitats with variable resources. Other species exhibit a wide variety of life histories, including direct development and viviparity. Their great abundance makes them important in the nutrient dynamics of many terrestrial and freshwater systems. They are the most threatened vertebrates; more than 50% of species are threatened, and even in pristine, protected areas they have been hard hit by epidemics of an emerging disease.

Host selection and distribution of Hypermastus placentae (Eulimidae), and ectoparasitic gastropod on the sand dollar Arachnoides placenta (Echinoidea)

Marine and Freshwater Research, 1993

Population dynamics of an ectoparasitic gastropod, Hypermastus sp. (Eulimidae), on the sand dollar, Arachnoides placenta (Echinoidea)

Marine and Freshwater Research, 1991

The association between the sand dollar, Arachnoides placenta, and the eulimid gastropod, Hyperma... more The association between the sand dollar, Arachnoides placenta, and the eulimid gastropod, Hypermastus sp., was investigated at Pallarenda Beach, Townsville, Queensland. Hypermastus sp. is a temporary ectoparasite of A. placenta that penetrates the latter&amp;amp;amp;amp;amp;amp;amp;#39;s test to ingest gonad tissue and coelomic fluid. The infestation rate normally varies between 8 and 15% but increases in winter to 26%. This seasonal increase in the infestation rate appears to be due to an increase in the duration of attachment of female parasites. Hypermastus sp. is sexually dimorphic, with males being, on average, 0.6 times the size of females. Individuals may be protandric sequential hermaphrodites.

Can length frequency analysis be used to determine squid growth? – An assessment of ELEFAN

Ices Journal of Marine Science, Aug 1, 2000

Current scientific literature presents two viewpoints regarding squid growth. One view suggests t... more Current scientific literature presents two viewpoints regarding squid growth. One view suggests that squid have long life spans and asymptotic growth. This viewpoint exists primarily as a direct consequence of researchers fitting asymptotic growth curves to squid length-frequency data. The second view arises from statolith ageing and culture studies, which have produced a divergent description of squid growth, specifically, a rapid non-asymptotic growth pattern that is linear or exponential in form, with short life spans. We revisit this controversy by producing and analysing a computer simulated squid length-frequency distribution. Our computer program produced a series of 30 d length frequencies based on biological parameters of an exponentially growing tropical near-shore loliginid with a sub-annual life span. We then analysed our computer generated data with the ELEFAN software program which produced asymptotic von Bertalanffy growth curves and life spans of up to 35 months for our simulated squid which had a life span of <200 d. This demonstrates at least 2 points; (1) that length frequency analysis is an inadequate means of describing growth for a rapid growing organism with multiple cohorts and (2) ELEFAN is not suitable for application to exponential growing organisms as it assumes a wrong model of asymptotic von Bertalanffy growth.

Download

Habitat Use and Positional Behavior of Anuran Larvae in a Northern Florida Temporary Pond

Copeia, May 9, 1986

... A number of field and lab-oratory studies (Alford and Wilbur, 1985; NATURAL populations of an... more

The history of amphibian declines in Australia

Bleak future for amphibians

Nature, Dec 1, 2011

[Extract] The major threats to amphibian species include pandemic disease and changes in climate ... more

Host thermoregulatory constraints predict growth of an amphibian chytrid pathogen (Batrachochytrium dendrobatidis)

Journal of Thermal Biology, 2020

Download

Infection intensity and sampling locality affectBatrachochytrium dendrobatidisdistribution among body regions on green-eyed tree frogsLitoria genimaculata