Parliamentary Briefing Note
Our research is featured in this recent Parliamentary Briefing Note on climate change and fisheries
PhD success for Lowri Evans!
Congratulations to PhD student Lowri Evans, who recently defended her thesis and successfully passed her viva.
Well done Lowri!
"How Global Warming Is Shrinking Earth's Animals" - our research is featured in Scientific American
We are delighted that our research investigating the temperature-size rule was recently featured in Scientific American. The article describes how a rise in global temperatures may be causing a reduction in the body size of species, highlighting some of the possible implications from such trends.
Our work on body size reductions with warming in aquatic species is on-going and funded by the Natural Environment Research Council (NERC).
The article can be found here.
A warm welcome to new PhD student Guille Garcia Gomez
We are very pleased to welcome new PhD student, Guille Garcia Gomez.
Guille will work on his PhD with David Atkinson, Leonie Robinson and Andrew Hirst. He will explore major patterns in the relationship between metabolic rates and body size in aquatic species. Such patterns are important because, while these relationships are very strong and relate to the use of energy by species, we still lack a universal understanding of how they are controlled. Guille will work on developing new theories to explain the major differences observed in metabolic scaling between organisms from different habitats and with different life histories, including making novel measurements to test these ideas.
Our new paper quantifying the causes of death in zooplankton is out now
The causes of zooplankton mortality have been little studied, but understanding this issue is key to appreciating the population dynamics of these important organisms. See our new paper quantifying causes of death in the common North Atlantic copepod species Calanus helgolandicus, published in Limnology and Oceanography.
New paper shows changes in insect size with altitude are diverse and do not follow the usual temperature-size rule
Our latest paper explores how body size changes with altitude in 121 insect species from 50 global locations - from butterflies in Costa Rica, to grasshoppers in the Swiss Alps, to bees at Mt. Kilimanjaro.
Recent work has shown that animal groups, including insects, displaying some of the strongest reductions in size with warming in the laboratory are also those that show the strongest reductions in size towards the equator. Whether size variation is equally predictable across altitude, and whether this closely resembles body size responses to temperature measured in the laboratory, is unknown.
We reveal widespread variation in the extent to which body size changed, and whether size increased or decreased, with altitude. Unlike major gradients in adult body size with latitude and season, which are generally consistent with the temperature-size rule observed under controlled conditions, few clear trends in size emerge with altitude. Many environmental factors interact across elevations, such as season length and oxygen availability, likely obscuring size differences between localities. The movement of individuals between different altitudes may also result in population mixing and less local adaptation, further obscuring size differences.
With many species retreating to colder higher elevations with climate warming, our work also highlights the complexities associated with how altitude impacts the body size of species.
Congratulations to Curtis Horne & Jacqueline Maud on their PhD success!
Very well done to you both!
Hirst Lab welcomes new PhD students Hanrong Tan & Laura Lee
Hanrong recently completed a Masters Degree at Basel University, Switzerland. During his PhD he will investigate how ectotherms (cold-blooded animals) are impacted by climate warming. This will include examining the mechanisms which determine the distribution, phenology and physiology of organisms, and how these are impacted by temperature and environmental conditions.
Laura recently completed an MRes at Nottingham University. Laura's PhD will explore how consideration of an organism’s fourth dimension – its biological “timescale” (generation time or life span), rather than rates standardised per unit of time, can help explain much about the pace of biology. Her work will include exploring the speed and allometry of growth, reproduction and energy consumption by diverse terrestrial and aquatic organisms worldwide. Laura is co-supervised by David Atkinson (Liverpool University) and Lev Ginzburg (Stony Brook University, USA).
New paper shows widespread body size reduction with seasonal warming in copepods
We present the first global synthesis of copepod temperature-body size responses in nature across seasons, published in Global Ecology and Biogeography.
Body size affects vital physiological rates and ecological processes. Ectotherms commonly grow to a smaller adult body size when reared in warmer conditions. Whilst temperature-body size responses have been well studied under controlled experimental conditions and across geographical ranges, comprehensive analyses of temporal changes are lacking. What’s more, there remains considerable unexplained variation in body size responses within aquatic species.
We analyzed published literature on seasonal body size responses of planktonic copepods, including 140 responses from 33 locations worldwide. Temperature was a much better predictor of adult body size change than chlorophyll-a concentration (a proxy for food availability), and almost 90% of species reduced their body size with seasonal warming. These reductions in size across generations within a year appear strongest in current-feeding calanoid species, compared to ambush-feeding cyclopoid species, suggesting feeding strategy may play a significant role in dictating the extent of body size reduction with warming.
Copepods globally represent a primary resource for invertebrates and vertebrates, from fish to whales. Changes in body size will not only affect individual and population fitness, but may have an impact on feeding rates and alter food web connectivity given the size dependency of trophic processes, as planktonic food webs are especially highly size structured.
To access the paper click here.
Our paper in Proceedings B explores the effects of warming on sexual size dimorphism in arthropods
Differences in body size between males and females, termed Sexual Size Dimorphism (SSD), can be marked within animal and plant species. While the degree of size difference can be affected by environmental conditions, until now the effect of temperature on SSD in ectotherms has not been extensively examined. In the most comprehensive analysis of its type to date, we compare the effects of temperature during development of adult body size in males and females of 85 diverse arthropod species from marine, freshwater and terrestrial environments.
Including a wide range of animal body sizes and variation in the degree of SSD, and differences in the sign of their response to warming (shrinking or enlarging with elevated temperatures), we find that the sexes show similar proportional changes in size on average. This suggests that temperature-size responses may generally have equivalent fitness costs and benefits in both sexes of a species.
Curtis’ photograph of a dance fly (right) is featured on the front cover.
To access the paper click here.
PhD student Curtis Horne awarded prize at Aquatic Biodiversity and Ecosystems Conference
Last week the University of Liverpool hosted the Aquatic Biodiversity and Ecosystems Conference, which invited aquatic scientists from both marine and freshwater disciplines to present and share their work on a number of broad themes, including Global Environmental Change and Evolutionary Biology. Delegates representing 141 institutes from over 40 countries attended the conference, including our own PhD student Curtis Horne.
Curtis presented his latest work, published in Ecology Letters earlier this year, in a talk entitled "Are temperature- and latitude-size clines driven by the same selective pressures?" and was 1 of 3 early career researchers to be awarded a prize for 'Best Talk'. Congratulations Curtis!
New paper in Ecology Letters: Our latest research helps unify major theories on what controls body size in ectotherms
Our new paper, published in Ecology Letters, compares existing data from across the world to identify major patterns in the sensitivity of arthropod body size to temperature and latitude.
Cold blooded animals frequently grow to a smaller adult size in the warm than in the cold. Curiously, aquatic animals reduce their body size much more with warming than those on land. For the first time, we show that these responses closely match body size patterns seen across latitudes. Within single species, aquatic animals tend to get smaller towards the equator, whilst most animals on land show much weaker or even opposite patterns.
To access the paper, click here.
We welcome new PhD student Lowri Evans
We are delighted to welcome new PhD student Lowri Evans, who recently joined our group as part of the first London NERC Doctoral Training Partnership.
Lowri's experience lies within fisheries, benthic ecology and marine protected area (MPA) management, both within the UK and further afield. Her PhD aims to develop our understanding of changes in the phenology and spatial distribution of marine organisms in relation to climate change. This includes quantitatively examining the global re-distribution of plankton, nekton and benthic species in space and time in relation to their functional traits.
To read Lowri's full profile, click here.
New paper in Ecology Letters: Shape shifting pelagic invertebrates resolve long-standing metabolic scaling questions.
In a new paper in Ecology Letters, we use the diverse shape shifting abilities of pelagic invertebrates to test competing theories of how metabolism scales with body size. Comparing the divergent predictions from models built on internal resource transport networks and those based on limits set by surface area exchange, with data from over 250 pelagic animals, we find strong support for the surface area dependent models.
The work was featured as Ecology Letters' front cover lead article.
To acces the paper, click here.
A warm welcome to Dr. Martin Lilley
On the 30th June 2014 we welcomed Dr. Martin Lilley to our team, who has joined the Hirst Lab as a postdoctoral researcher.
Martin brings with him a wealth of marine biological research experience, from studying jellyfish and sea turtles, to examining growth of sea urchin larvae, benthic grab sampling and rocky shore experimental ecology.
Martin is employed as part of a NERC-funded project that aims to examine marine food webs, assessing how species interactions will cope with environmental change.
To read Martin's full profile, click here.
Sex, plankton and predators
Some of our recent work has been featured in the latest Winter 2013 edition of NERC'S news publication, Planet Earth. Entitled 'Sex, Plankton and Predators', the article presents research by Dr. Tania FitzGeorge-Balfour, who explains why the sex-ratios of many adult copepod populations are commonly very female biased.
Dr. Tania FitzGeorge-Balfour was based at Queen Mary University of London (QMUL) and supervised by Dr. Andrew Hirst (QMUL) and Dr. Cathy Lucas of the National Oceanography Centre in Southampton, this work formed part of an NERC-funded project.
To read the article, click here.
More news coming soon...
“Shifts in mass-scaling of respiration, feeding, and growth rates across life-form transitions in marine pelagic organisms” - our first publication of 2014.
As part of our collaboration with colleagues at the Centre for Ocean Life in Denmark, our first paper of 2014 has been published in The American Naturalist.
Marine pelagic organisms, from microscopic flagellates to large fish, are remarkably similar in their feeding performance and metabolic rates, but intriguingly we find that relative consumption and growth rates decline as organisms get larger. Changes in an individual's body plan and feeding efficiency may be a necessary trade-off to compensate for declining food availability in the ocean as their body size increases.
To view the press release, click here.
To read the full paper, click here.
Aquatic ecosystems have a profound impact on humankind and the biosphere, and can provide critical insight into biological questions. Using marine and freshwater organisms our research aims to mechanistically understand and predict rules of physiology and ecology. We examine physiology, vital rates and ocean biogeochemistry, including assessing the impacts of climate change. In our work we use diverse approaches including meta-analysis, experimentation, fieldwork and modelling.