College of Science and Engineering CSE publications Recent publications in Science and Engineering

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Recent publications in Science and Engineering

Schlaefer, Jodie A., Wolanski, Eric, Lambrechts, Jonathan, and Kingsford, Michael J. (2021) Behavioural and oceanographic isolation of an island-based jellyfish (Copula sivickisi, Class Cubozoa) population. Scientific Reports, 11. 10280.
Cubozoan jellyfish are classified as plankton despite the strong swimming and orientation abilities of cubomedusae. How these capabilities could affect cubozoan population structures is poorly understood. Medusae of the cubozoan Copula sivickisi can uniquely attach to surfaces with the sticky pads on their bells. Biophysical modelling was used to investigate the spatial scales of connectivity in a C. sivickisi population. When the medusae were active at night they could maintain their observed distribution on fringing reef if they attached to the reef when the current speed exceeded a moderate threshold. This behaviour facilitated the isolation of a C. sivickisi population on reefs fringing Magnetic Island, Queensland, Australia. Within this distribution, there was considerable within bay retention and medusae rarely travelled > 3 km. The few (< 0.1%) medusae lost from the island habitat were largely advected into open water and away from the mainland coast which lies 8 km from the island. Given that successful emigration is unlikely, the island population probably represents a stock that is ecologically distinct from any mainland populations. The cosmopolitan distribution of C. sivickisi could contain incipient or cryptic species given the small scales of connectivity demonstrated here.

Wang, Ju-Han Zoe, and Connell, John (2021) Taiwanese working holiday makers in rural and regional Australia: temporary transnational identities and employment challenges. Australian Geographer. (In Press)
Working Holiday Makers (WHMs) from overseas have been a valuable source of employment in rural and regional Australia. This is one significant part of a growing resort to temporary migration to meet employment problems especially in regional areas. Little is known about the experience and contribution of Asian WHMs despite the presence of significant numbers, especially from Taiwan. Most Taiwanese WHMs are young educated women who have moved in search of cultural experiences and reasonable incomes. Analysis of media reports in Australia and Taiwan reveals an entirely negative perception of such migrants and their everyday circumstances that denies diversity, agency and contribution to regional economies. Taiwanese media are more likely to focus on exploitation. Being a WHM provides a distinctive transnational experience balancing travel as a cultural experience with a marginal employment experiences. New research is required to redress this limited context and evaluate the actual significance of these substantial temporary migrant flows.

Baker, Stephanie, Xiang, Wei, and Atkinson, Ian (2021) Determining respiratory rate from photoplethysmogram and electrocardiogram signals using respiratory quality indices and neural networks. PLoS ONE, 16 (4). e0249843.
Continuous and non-invasive respiratory rate (RR) monitoring would significantly improve patient outcomes. Currently, RR is under-recorded in clinical environments and is often measured by manually counting breaths. In this work, we investigate the use of respiratory signal quality quantification and several neural network (NN) structures for improved RR estimation. We extract respiratory modulation signals from the electrocardiogram (ECG) and photoplethysmogram (PPG) signals, and calculate a possible RR from each extracted signal. We develop a straightforward and efficient respiratory quality index (RQI) scheme that determines the quality of each moonddulation-extracted respiration signal. We then develop NNs for the estimation of RR, using estimated RRs and their corresponding quality index as input features. We determine that calculating RQIs for modulation-extracted RRs decreased the mean absolute error (MAE) of our NNs by up to 38.17%. When trained and tested using 60-sec waveform segments, the proposed scheme achieved an MAE of 0.638 breaths per minute. Based on these results, our scheme could be readily implemented into non-invasive wearable devices for continuous RR measurement in many healthcare applications.

Tucker, Robert, Khatamifar, Mehdi, Lin, Wenxian, and McDonald, Kyle (2021) Experimental investigation of orientation and geometry effect on additive manufactured aluminium LED heat sinks under natural convection. Thermal Science and Engineering Progress, 23. 100918.
The continued adaptation of light-emitting diodes (LEDs) presents challenges for heat dissipation. LEDs are considered to be high power density devices, as such effective thermal management is imperative for extended usage. In this study, new design considerations such as adapting middle fin, fin height gradient towards the centre of the heat sink, along with fin perforations and a spiral cut out of the central pillar have been incorporated into heat sinks to assist convection. The heat sinks were manufactured out of aluminium alloy (AlSi10Mg) using the selective laser melting (SLM) method. The effects of orientation on the heat transfer of different heat sink geometries were experimentally studied under natural convection conditions. The performance of six different geometries with 6, 8 and 10 long fins (6LF, 8LF and 10LF) with and without middle fins were evaluated under three different heat flux conditions (471.57 , 943.14 and 1257.52 ) for 10 different orientation angles (0-90). The higher fin density heat sinks are found to have lower orientation dependency. The convective fluid flow of the higher fin density geometries is significantly hindered by the overlapping of thermal boundary layers. The increase in the Rayleigh number has the most significant effect on the 6LF heat sink. The overall Nusselt number correlations for the 6LF, 8LF and 10LF heat sinks with short fins are and , respectively. Removing short fins improved heat transfer rate for all heat sinks.

Dong, Liqiang, Lin, Wenxian, and Khatamifar, Mehdi (2021) Experimental study on the intrusion and stratification produced by confined laminar and turbulent round fountains. International Journal of Heat and Fluid Flow, 89. 108785. pp. 1-26.
In this paper, high-speed cameras and flow visualization techniques are used to investigate the behavior of the ‘fountain filling box’ flow resulted from releasing a round fountain in a homogeneous quiescent fluid in a cylindrical container over the ranges of 1.0⩽Fr⩽20.0,102⩽Re⩽1502, and 27.9⩽λ⩽48.75, where Fr,Re and λ are the Froude number, the Reynolds number, and the dimensionless radius of the container, respectively, with λ non-dimensionalized by the fountain source radius. The results show the transition of the flow behavior of the fountain and its secondary flows (i.e., the intrusion, reversed flow and stratification) from laminar to turbulent with increasing Fr, and turbulence of the flow strengthened with increasing Re. For intermediate (e.g., Fr=3.0) and forced turbulent fountains (e.g., Fr=5.0, 8.0, 15.0) with a specific λ, the non-dimensionalized time-scale for the intrusion front to impinge upon the sidewall, τw, is nearly constant for Re≳500. This is because the secondary intrusion flow is dominated by the wall-jet and buoyancy-inertial regimes where the non-dimensionalized intrusion front velocity, vi, is only time-dependent (vi~τ-1/2) or time-dependent but also under the influence of Fr (vi~Fr-1/2τ-1/4). However, τw for the fountains of Re≲204 is significantly different, which may result from the change in the dominant regime for the intrusion or the interaction between the upflow, downflow of the fountain and the ambient fluids. Furthermore, it is found that the non-dimensionalized quasi-steady development rate of the stratification, vs, increases with Fr, but decreases with Re, since the diffusion effect is suppressed with decreasing Fr or increasing Re.

Clements, Kendall D., German, Donovan P., Piche, Jacinthe, Tribollet, Aline, and Choat, John Howard (2021) Integrating ecological roles and trophic diversification on coral reefs: multiple lines of evidence identify parrotfishes as microphages. Biological Journal of the Linnean Society. (In Press)
Coral reef ecosystems are remarkable for their high productivity in nutrient-poor waters. A high proportion of primary production is consumed by the dominant herbivore assemblage, teleost fishes, many of which are the product of recent and rapid diversification. Our review and synthesis of the trophodynamics of herbivorous reef fishes suggests that current models underestimate the level of resource partitioning, and thus trophic innovation, in this diverse assemblage. We examine several lines of evidence including feeding observations, trophic anatomy, and biochemical analyses of diet, tissue composition and digestive processes to show that the prevailing view (including explicit models) of parrotfishes as primary consumers of macroscopic algae is incompatible with available data. Instead, the data are consistent with the hypothesis that most parrotfishes are microphages that target cyanobacteria and other protein-rich autotrophic microorganisms that live on (epilithic) or within (endolithic) calcareous substrata, are epiphytic on algae or seagrasses, or endosymbiotic within sessile invertebrates. This novel view of parrotfish feeding biology provides a unified explanation for the apparently disparate range of feeding substrata used by parrotfishes, and integrates parrotfish nutrition with their ecological roles in reef bioerosion and sediment transport. Accelerated evolution in parrotfishes can now be explained as the result of (1) the ability to utilize a novel food resource for reef fishes, i.e. microscopic autotrophs; and (2) the partitioning of this resource by habitat and successional stage.

Lal, Alvin, and Datta, Bithin (2021) Optimal pumping strategies for the management of coastal groundwater resources: application of Gaussian Process Regression metamodel-based simulation-optimization methodology. ISH Journal of Hydraulic Engineering. (In Press)
The present study utilizes a coupled simulation-optimization (S-O) methodology to develop a multi-objective management strategy for a coastal aquifer system. The aim of the multi-objective management model is to maximize pumping from freshwater wells (FWs) and minimize pumping from the barrier wells (BWs), while keeping salinity concentration in the aquifer within pre-specified limits (optimization constraint). To achieve computational feasibility of the management model, the numerical simulation model is substituted by the relatively new Gaussian Process Regression (GPR) metamodels. The GPR models are used to approximate coastal aquifer responses to variable transient pumping patterns from FWs and BWs. Prediction capabilities of the developed GPR metamodels are quantified using standard statistical parameters. Once trained and validated, the GPR metamodels are coupled to a multi-objective genetic algorithm optimization model and used to prescribe optimal groundwater pumping patterns. The outcomes of this study establishes the potential applicability of the GPR metamodel-based S-O model for developing sustainable coastal groundwater management strategies, which can utilize accurate and efficient prediction of management strategy impacts on the saltwater intrusion (SI) process when the optimal management policy development is based on the trained metamodel predictions. Once implemented, the developed strategy can help in controlling SI in coastal aquifer systems.

Staunton, Kyran M., Crawford, Jacob E., Liu, Jianyi, Townsend, Michael, Han, Yu, Desnoyer, Mark, Howell, Paul, Xiang, Wei, Burkot, Thomas R., Snoad, Nigel, and Ritchie, Scott A. (2021) A low-powered and highly selective trap for male Aedes (Diptera: Culicidae) surveillance: the male Aedes sound trap. Journal of Medical Entomology. (In Press)
As Aedes aegypti (Linnaeus, Diptera: Culicidae) expands its global distribution and vectors a range of debilitating arboviruses there is an increased need for enhanced mosquito surveillance. Consequently, we developed a Male Aedes Sound Trap (MAST) that requires minimal power and is highly species-specific. Two different versions of the MAST were developed, one that uses synthetic pyrethroid to kill captured mosquitoes (MAST Spray) and another which has an internal divider to create a killing chamber in which a sticky panel can be placed to capture mosquitoes (MAST Sticky). We compared weekly capture rates of male Ae. aegypti and bycatch from the two MAST versions to those from BG-Sentinel (BGS) traps and Sound-producing BG-Gravid Aedes Traps (SGATs) throughout Cairns, northern Australia. Weekly mean male Ae. aegypti catches did not significantly differ between trap types. However, the rate of positive weekly detections of male Ae. aegypti was lower for the MAST Sticky than the other three trap types. The MASTs sampled significantly fewer mosquitoes other than male Ae. aegypti, than either the BGS trap or the SGAT. Also, the MASTs and SGATs all caught significantly less non-Culicidae bycatch than the BGS traps. Consequently, we have developed a versatile male Ae. aegypti trap which is potentially of great benefit to Ae. aegypti surveillance programs.

MacKeracher, Tracy, Mizrahi, Me'ira, Bergseth, Brock, Chit Maung, Khin May, Khine, Zin Lin, Phyu, Ei Thal, Simpfendorfer, Colin A., and Diedrich, Amy (2021) Understanding non-compliance in small-scale fisheries: shark fishing in Myanmar's Myeik Archipelago. Ambio, 50. pp. 572-585.
Achieving fisheries compliance is challenging in contexts where enforcement capacity is limited and the incentives for rule-breaking are strong. This challenge is exemplified in Myanmar, where an active shark fishery exists despite a nationwide ban on targeted shark fishing. We used the Kipling method (5W1H) to gather a complete story of non-compliance in five small-scale fishing communities in the Myeik Archipelago. Among 144 fishers surveyed, 49% were aware of the nationwide ban. Shark fishers (24%) tended to be younger individuals who did not own a boat and perceived shark fishing to be prevalent. Compliant fishers were motivated by a fear of sharks and lack of capacity (equipment, knowledge), whereas food and income were cited as key motivations for non-compliance. The results of our study emphasize that in resource-dependent communities, improving compliance for effective shark conservation may require addressing broader issues of poverty, food security and the lack of alternatives.

Rowell, Misha K., and Rymer, Tasmin L. (2021) Growth and behavioural development of the fawn-footed mosaic-tailed rat (Melomys cervinipes). Australian Mammalogy. (In Press)
The fawn-footed mosaic-tailed rat (Melomys cervinipes) is a common Australian rainforest rodent; however, little is known about the growth or behavioural development of individuals of this species. We raised mosaic-tailed rats in captivity to assess the growth and behavioural development of pups from birth until weaning. Pups developed quickly compared with some other Australian species, and there were no significant differences in growth between males and females, except for anogenital distance. The auditory meatus was open by Postnatal Day 5, and eyes were fully opened by Postnatal Day 9. All behaviours, including righting, locomotion, negative geotaxis, climbing and grip reflex, were fully developed by Postnatal Day 6. These results suggest that mosaic-tailed rats are semiprecocial in their physical and behavioural development compared with some native Australian rodent species that are found in arid environments. As females produce few, relatively well-developed young, the population has a low intrinsic rate of natural increase. This may, however, be offset by mosaic-tailed rats producing more litters per year. Understanding the biology of mosaic-tailed rats in general could provide insights into how rarer precocial species might struggle to increase in population size under increasing disturbances.

Hopkins, Jaimie M., Higgie, Megan, and Hoskin, Conrad J. (2021) Calling behaviour in the invasive Asian house gecko (Hemidactylus frenatus) and implications for early detection. Wildlife Research. (In Press)
Context. Acoustic communication is common in some animal groups, with an underlying function typically associated with mating or territoriality. Resolving the function of calls is valuable both in terms of understanding the fundamental biology of the species and, potentially, for applied reasons such as detection. Early detection is a key step in exclusion and eradication of invasive species, and calling behaviour can be used in this regard. The Asian house gecko (Hemidactylus frenatus) is one of a minority of lizards that uses acoustic communication. However, despite how conspicuous the call is, its function remains poorly resolved. It is also one of the world's most invasive species, with exclusion via early detection being the key form of control. Aims. The aim was to resolve calling patterns and underlying function of the loud, multiple-chirp call ('chik, chik, chiky') in H. frenatus, in the context of using the results for developing effective methods for detection of new and establishing populations. Methods. The calls of wild H. frenatus were recorded to assess peaks in calling activity. Also, laboratory experiments were performed to determine which individuals call, what causes them to call and the degree of call variation among individuals. Key results. Assessment of calling behaviour in the wild revealed greater calling activity in warmer months, and five- to 10-fold peaks in calling activity at sunset and 30 min before sunrise. Laboratory experiments revealed that calls were uttered exclusively by males and primarily by adults (although juveniles can call). Males called more when they were paired with females as opposed to other males. Calls differed among geckos, including the expected negative correlation between dominant frequency and body size. Conclusions. The results suggest that the multiple-chirp call functions as a territory or sexual broadcast by males, perhaps containing information such as body size. Implications. Detection success can be maximised by performing acoustic surveys (by human or machine) during the calling peaks at 30 min before sunrise and at sunset, particularly during warm nights. However, these surveys will only be effective for detecting adult males. The results also suggest that good quality recordings could potentially be used to identify individual geckos.

Ziegler, Alan D., Lim, H.S., Wasson, Robert J., and Williamson, Fiona C. (2021) Flood mortality in SE Asia: can palaeo‐historical information help save lives? Hydrological Processes, 35 (1). e13989.
[Excerpt] Asia is one of the world's most flood-prone regions by many metrics: high flood magnitudes, frequency, severity; the number countries affected, the area of inundation; the number of people at risk; and importantly, flood-related fatalities (AIR, 2014; Luo, Maddoks, Iceland,Ward, & Winsemius, 2015; Table 1). With respect to mortality, nearly all the countries with more than 5,000 flood-related deaths since 1985 are from Asia (11 of 13; Table 1; Figure 1). As we write this commentary, flooding associated with tropical storm Nangka has caused more than 40 deaths in Laos, Cambodia, and Vietnam(Floodlist, 2020).

Brown, Colin, Behrendt, Karl, Ping, Li, Guanghua, Qiao, Bennett, Jeff, Bao, Zhang, Addison, Jane, Kemp, David, Guodong, Han, and Jing, Zhang (2021) Refining China's grassland policies: an interdisciplinary and ex-ante analysis. The Rangeland Journal, 42 (6). pp. 435-445.
China is about to embark on a new round of grassland policies as part of its 14th Five-Year-Plan. While current grassland policies have generally been perceived positively in arresting widespread grassland degradation, concerns have arisen that the current policies may not be effective in achieving the desired reduction in livestock numbers. Furthermore there are concerns the incentive based payments that are part of these policy programs may not reflect herder opportunity costs or the marginal environmental benefits of the program with associated issues of herder satisfaction and compliance. Changes to current policy settings are being considered in response to these concerns. This paper reports on an interdisciplinary and ex-ante analysis of alternative policy settings affecting grazing and livestock management in terms of their environmental impacts, net social benefits and other impacts. The analysis finds that a bundle of instruments involving both positive and negative herder incentives is needed if desired stocking rates are to be achieved. The impact on herder incomes, both positive and negative depending on the grassland biome, along with transaction costs of implementing the policies, have the most influence on net social benefits.

Yeeles, Peter, Strain, Angela, Lenancker, Pauline, and Lach, Lori (2021) Low reduction of invasive ant colony productivity with an insect growth regulator. Pest Management Science. (In Press)
Background Insect growth regulators (IGRs) generally are considered to have safer eco-toxicological profiles than the more commonly used neurotoxins and metabolic inhibitors, and are extremely effective against several insect groups, including some invasive ant species. However, use of an IGR product in a large-scale eradication program for a widespread invasive ant (Anoploepis gracilipes; yellow crazy ant) was ineffective. We tested the IGR in question (active ingredient: (S)-methoprene) on A. gracilipes colonies in a laboratory environment to evaluate efficacy. Results We found that treatment with (S)-methoprene resulted in lower egg production with subsequently decreased numbers of larvae, pupae, and workers over the 135 days of the experiment. None of the treated colonies died, and the number of worker ants in treated colonies was 36% of that seen in control colonies 135 days post-treatment. Treated queen egg production was 39% lower than queens in control colonies, but we saw no effect of treatment on the internal physiology of dissected queens. Treatment had no effect on worker activity levels. Conclusion Our results show that although (S)-methoprene treatment reduced production of larvae, pupae and workers in treated colonies, the magnitude of reduction was lower than might be expected considering the responses of other species against which this IGR has been tested. Our findings highlight a need for testing species-specific responses to IGR-based insecticides in a controlled environment, before broad-scale field applications that could result in suboptimal management of the target species.

Younes, Nicolas, Joyce, Karen E., and Maier, Stefan M. (2021) All models of satellite-derived phenology are wrong, but some are useful: a case study from northern Australia. International Journal of Applied Earth Observation and Geoinformation, 97 (102285).
Satellite-derived phenology (or apparent phenology) is frequently used to illustrate changes in plant phenology (i.e. true phenology) and the effects of climate forcing. However, each study uses a different method to detect phenology. Plant phenology refers to the relationship between the life cycle of plants and weather and climate events. Phenology is often studied in the field, but recently studies have transitioned towards using satellite images to monitor phenology at the plot, country, and continental scales. The problem with this approach is that there is an ever-increasing variety of earth observation satellites collecting data with different spatial, spectral, and temporal characteristics. In this paper we ask if studies that detect phenology using different sensors over the same site produce comparable results. Mangrove forests are one example where different methods have been used to examine their apparent phenology. In general, plant phenology, including mangroves, is described using few individual plants, but continental-scale descriptions of phenological events are scarce or inexistent. Few attempts have been made to describe the phenology of mangroves using satellite imagery, and each study presents a different method. We hypothesize that apparent phenology changes with: 1) areal extent; 2) site location; 3) frequency of observation; 4) spatial resolution; 5) temporal coverage; and 6) the number of cloud contaminated observations. Intuitively, one would assume that these hypotheses hold true, yet few studies have investigated this. For example, one would expect that clouds change the observed phenology of vegetation, that the number of species captured at spatial resolution will impact the apparent phenology, or that mangroves in different places display different phenologies, but how are these changes represented in the apparent phenology? We use the Enhanced Vegetation Index (EVI) to examine the changes in the start of season and peak growing season dates, as well as the shape and amplitude of the apparent phenology in each hypothesis. We use Landsat and Sentinel 2 imagery over the mangrove forests in Darwin Harbour (Northern Territory, Australia) as a case study, and found that apparent phenology does change with the sensor, site, and cloud contamination. Importantly, the apparent phenology is comparable between Landsat and Sentinel 2 sensors, but it is not comparable to phenology derived from MODIS. This is due to differences in the spatial resolution of the sensors. Cloud contamination also significantly changes the apparent phenology of vegetation. In this paper we expose the complexity of modelling phenology with remote sensing and help guide future phenology investigations.

Chaitae, Apinya, Gordon, Iain J., Addison, Jane, and Marsh, Helene (2021) From protection of elephants to sustainable use of ivory in Thailand. Oryx. (In Press)
The elephant has deep cultural significance in Thailand and for the Thai people. The development of legal protection for Thai elephants reflects concerns about both human livelihoods and elephant conservation. Thus, the legal status of privately-owned domesticated, or captive Asian elephants, differs from that of wild Asian elephants, a situation that has consequences for the lawful use of ivory from domesticated animals. Prior to 2015, the lack of comprehensive measures to control the Thai ivory market enabled the laundering of illegally-sourced ivory through the country. The 2015 legal reforms of the Thai Government: 1) introduced strict controls over the possession and domestic trade of ivory from domesticated Asian elephants, and 2) aligned the protection of African elephants and their ivory with the CITES Convention. Nonetheless, the sustainability of the Thai ivory trade remains disputed, and international pressure to close the commercial trade in domestic ivory persists. This paper reviews this complex situation to inform future reforms. Consolidation of related laws would ease the enforcement tasks of officers and facilitate the compliance of stakeholders. Use of an electronic database would enhance the monitoring of ivory flow, as well as aid the implementation and enforcement of laws. This situation is a valuable example of the tensions between national and international attempts to conserve species important in wildlife trade.

Rowe, Cassandra, Wurster, Christopher M., Zwart, Costijn, Brand, Michael, Hutley, Lindsay B., Levchenko, Vladimir, and Bird, Michael I. (2021) Vegetation over the last glacial maximum at Girraween Lagoon, monsoonal northern Australia. Quaternary Research. (In Press)
Northern Australia is a region where limited information exists on environments at the Last Glacial Maximum (LGM). Girraween Lagoon is located on the central northern coast of Australia and is a site representative of regional tropical savanna woodlands. Girraween remained a perennial waterbody throughout the LGM, and as a result retains a complete proxy record of last glacial climate, vegetation and fire. This study combines independent palynological and geochemical analyses to demonstrate a dramatic reduction in tree cover, woody richness and expansion of grassland relative to current vegetation at the site. The process of tree decline was primarily controlled by the cool-dry glacial climate and CO2 effects, though more localised site characteristics restricted wetland associated vegetation. Fire processes played less of a role determining vegetation than in the Holocene and modern day, with reduced fire activity consistent with significantly lower biomass available to burn. This unique and detailed palaeoecological record provides the opportunity to explore and assess modelling studies of vegetation distribution during the LGM, particularly where a number of different global vegetation and/or climate simulations are inconsistent for northern Australia, and at a range of resolutions.

Belson, Bruce, Xiang, Wei, Holdsworth, Jason, and Philippa, Bronson (2021) C++20 coroutines on microcontrollers - what we learned. IEEE Embedded Systems Letters, 13 (1). pp. 9-12.
Coroutines will be added to C++ as part of the C++20 standard. Coroutines provide native language support for asynchronous operations. This study evaluates the C++ coroutine specification from the perspective of embedded systems developers. We find that the proposed language features are generally beneficial but that memory management of the coroutine state needs to be improved. Our experiments on an ARM Cortex-M4microcontroller evaluate the time and memory costs of coroutines in comparison with alternatives, and we show that context switching with coroutines is significantly faster than with thread-based real time operating systems. Furthermore, we analysed the impact of these language features on prototypical IoT sensor software. We find that the proposed language enhancements potentially bring significant benefits to programming in C++ for embedded computers, but that the implementation imposes constraints that may prevent its widespread acceptance among the embedded development community.

Silva, Catarina N.S., Murphy, Nicholas P., Bell, James J., Green, Bridget S,, Duhamel, Guy, Cockcroft, Andrew C., Hernández, Cristián E., and Strugnell, Jan M. (2021) Global drivers of recent diversification in a marine species complex. Molecular Ecology. (In Press)
Investigating historical gene flow in species complexes can indicate how environmental and reproductive barriers shape genome divergence during speciation. The processes influencing species diversification under environmental change remain one of the central focal points of evolutionary biology, particularly for marine organisms with high dispersal potential. We investigated genome‐wide divergence, introgression patterns and inferred demographic history between species pairs of all six extant rock lobster species (Jasus spp.), which have a long larval duration of up to two years and have populated continental shelf and seamount habitats around the globe at approximately 40oS. Genetic differentiation patterns reflected geographic isolation and the environment (i.e. habitat structure). Eastern Pacific species (J. caveorum and J. frontalis) were geographically more distant and genetically more differentiated from the remaining four species. Species associated with continental shelf habitats shared a common ancestry, but are geographically distant from one another. Similarly, species associated with island/seamount habitats in the Atlantic and Indian Oceans shared a common ancestry, but are also geographically distant. Benthic temperature was the environmental variable that explained most of the genetic differentiation (FST), while controlling for the effects of geographic distance. Eastern Pacific species retained a signal of strict isolation following ancient migration, whereas species pairs from Australia and Africa, and seamounts in the Indian and Atlantic oceans, included events of introgression after secondary contact. Our results reveal important effects of habitat and demographic processes on the recent divergence of species within the genus Jasus, providing one of the first empirical studies of genome‐wide drivers of diversification that incorporates all extant species in a marine genus with long pelagic larval duration.

Montesinos, Daniel (2021) Fast invasives fastly become faster: invasive plants align largely with the fast side of the plant economics spectrum. Journal of Ecology. (In Press)
1. Invasive plants generally align with the fast side of the plant's trait economics spectrum, characterized by fast nutrient acquisition, growth and reproduction. However, there are numerous and notable exceptions, including woody invasives. 2. The generalization that invasives are fast is driven by the high occurrence of invasive ruderal species colonizing nutrient-rich disturbed habitats, a consequence of anthropogenic disturbance usually going hand-in-hand with biological introductions. 3. Successful invasive plans have shown a remarkable ability to rapidly adapt to the new regions where they are introduced. These changes predominantly involve increased resource acquisition, growth and reproduction, aligning them even further with the fast side of the plant economics spectrum. 4. Common garden experiments with invasive model systems provide valuable insights about the speed and direction of adaptive responses to different climates, helping us to predict general plant responses to global change. 5. Synthesis. Invasive plant species commonly present fast nutrient acquisition, growth and reproduction, but this general pattern is mostly driven by ruderal species. Still, common garden experiments comparing populations from distant world regions show a clear trend for already fast invasive plants to rapidly adapt towards even faster traits in their non-native regions.

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