Biology subjects

Duffy, G. A.

Publications and source records attributed to Duffy, G. A..

3 recordsLinked to original sources

bioRxiv2024

Unlocking Antarctic molecular time-capsules - recovering historical environmental DNA from museum-preserved sponges

Marine sponges have recently emerged as efficient natural environmental DNA (eDNA) samplers. The ability of sponges to accumulate eDNA provides an exciting opportunity to reconstruct contemporary communities and ecosystems with high temporal and spatial precision. However, the use of historical eDNA (heDNA), trapped within the vast number of specimens stored in scientific collections, opens up the opportunity to begin to reconstruct the communities and ecosystems of the past. Here, using a variety of Antarctic sponge specimens stored in an extensive marine invertebrate collection, we were able to recover information on Antarctic fish biodiversity from specimens up to 20 years old. We successfully recovered 64 fish heDNA signals from 27 sponge specimens. Alpha diversity measures did not differ among preservation methods, but sponges stored frozen had a significantly different fish community composition compared to those stored dry or in ethanol. Our results show that we were consistently and reliably able to extract the heDNA trapped within marine sponge specimens, thereby enabling the reconstruction and investigation of communities and ecosystems of the recent past with a spatial and temporal resolution previously unattainable. Future research into heDNA extraction from other preservation methods, as well as the impact of specimen age and collection method will strengthen and expand the opportunities for this novel resource to access new knowledge on ecological change during the last century.

molecular biology↗

bioRxiv2022

Spatio-temporal development of the urban heat island in a socioeconomically diverse tropical city

Urban heat islands, where temperatures are elevated relative to non-urban surrounds, are near-ubiquitous in cities globally. Yet, the magnitude and form of urban heat islands in the tropics, where heat has a large morbidity and mortality burden, is less well understood, especially for socioeconomically diverse communities such as those living in urban informal settlements. We utilised 29 years of Landsat satellite-derived surface temperature, corroborated by in situ measurements, to provide a detailed spatial and temporal assessment of urban heat islands in Makassar, Indonesia, a city that is representative of rapidly growing urban settlements across the tropics. We did so with explicit consideration of vulnerable communities living informally. Our analysis identified surface urban heat islands of up to 9.2 {degrees}C in long-urbanised parts of the city and 6.3 {degrees}C in informal settlements, the seasonal patterns of which were driven by change in non-urban areas rather than in urban areas themselves. In recently urbanised areas, the majority of urban heat island increase occurred before areas became 50% urbanised. As tropical cities continue to expand we expect that urban heat islands will develop quickly as land is urbanised, whereas the established heat island in long-urbanised areas will remain stable in response to city expansion. Green and blue space protect some informal settlements from the worst urban heat islands and maintenance of such space will be essential to mitigate the growing heat burden from urban expansion and anthropogenic climate change. We advocate for green space to be prioritised in urban planning, redevelopment and informal settlement upgrading programs, with consideration of the unique environmental and socioeconomic context of tropical cities. HighlightsO_LILong-term, fine-scale data are essential to understand the dynamics of urban heat C_LIO_LISurface heat islands reached 9.2 {degrees}C in the urban core, 6.3 {degrees}C in informal settlements C_LIO_LIIn situ data support the use of remote sensing for heat island characterisation C_LIO_LIThe majority of heat island growth occurred before land was 50% urbanised C_LIO_LIGreen and blue space can mitigate heat in informal settlements C_LI

ecology↗

bioRxiv2018

A widespread thermodynamic effect, but maintenance of biological rates through space across life’s major domains

For over a century, temperature compensation (maintenance of biological rates with changing temperatures) has remained controversial. An alternative idea, that fitness is greater at higher temperatures (the thermodynamic effect), has gained increasing traction, and is being used to understand large-scale biodiversity responses to environmental change. Yet evidence in favour of each of these contrasting hypotheses continues to emerge. In consequence, the fundamental nature of organismal thermal responses and its implications remain unresolved. Here we investigate these ideas explicitly using a global dataset of 619 observations of four categories of organismal performance, spanning 14 phyla and 403 species. In agreement with both hypotheses, we show a positive relationship between the temperature of maximal performance rate (Topt) and environmental temperature (Tenv) for all traits. Next we demonstrate that relationships between Tenv and the temperature of maximal performance rate (Umax) are rarely significant and positive, as expected if a thermodynamic effect predominates. By contrast, a positive relationship between Topt and Umax is always present, but markedly weaker than theoretically predicted. These outcomes demonstrate that while some form of thermodynamic effect exists, ample scope is present for biochemical and physiological adaptation to thermal environments in the form of temperature compensation.

ecology↗