A prominent voice in the field of animal behaviour, Dr Lauren Brent discusses her research into the interaction of ageing and sociality with a fascinating look at the lives of two charismatic social mammals.

Dr Lauren Brent seems to live an animal behaviourist’s dream. Not only does she travel the world studying some of the world’s most interesting animals, but she also shines a light on the physiological and evolutionary explanations behind their behaviour. This Monday students and staff were treated to a look at how age affects an individual’s engagement with the social world, and on the flipside of this, how the pace at which individuals age is affected by social processes. These two themes were neatly explored using Dr Brent’s research on the southern killer whales of British Columbia and the charismatic rhesus macaques of Cayo Santiago, Puerto Rico.

It became immediately apparent in the seminar how passionate Dr Brent is about her work and how carefully she selected the subjects for her research. Breaking the talk into two sections, she first spoke about how aged based differences in these two animal groups affect their social interactions. The killer whales were followed to see how this impacted on their collective movement, questioning whether, and if so why, older, post-reproductive females led group movement. On the other side of the world, data associated with grooming and aggressive encounters between female rhesus macaques were collected to see whether age affected the frequency and reciprocity of these social interactions.

“Southern resident killer whales are one of only five species known to undergo menopause”

Southern resident killer whales are one of only five species known to undergo menopause, and there is no sex-based dispersal in populations, with the family unit choosing to stay together for life and outbreeding. The long post-reproductive period of females (lasting any time up to fifty years) is similar to humans’ in its length, and it was unknown what influence this had on the sociality of the older females. In Dr Brent’s 2015 paper, a study of over nine years’ worth of video footage of the whales was visualised into leadership networks. This resulted in the discovery that in comparison to males, females were more likely to lead and that relative to younger females, post-reproductive female whales were the most likely leaders. To understand these results, further study was undertaken to find the situations in which the older females were more likely to lead. This research revealed that older females were more likely to lead when populations of chinook salmon (the species making up at least 85% of southern killer whale diet) were low. It was apparent then that as their age increased female whales became more important in directing the collective movement of the pod, perhaps a clear indicator that the enhanced world experience that comes with age influences how these individuals engage with their social world.

“The population of rhesus macaques on Coyo Santiago was perfect for her research because of its extensive life history records and closed gene pool”

Described by Dr Brent as ‘despotic and nepotistic’, the population of rhesus macaques on Cayo Santiago was perfect for her research because of its extensive life history records and closed gene pool. Like the killer whales, the social structure of the population was explained as being a close-knit community in which the females stay (philopatry) but where the males disperse. Habituating a predator-free, food-rich environment exposed the social pressures of group living and highlighted the aggressive, competitive nature of the macaques. To see if the age of the individuals affected the frequency and intensity of their social interactions, the exposure of females to grooming and aggressive encounters was studied. No evidence was found to show older females received less grooming than younger females, and no evidence was found that they ‘gave’ less aggression. However, it was discovered that older females gave out less grooming and received less aggression, clearly showing at some level age is affecting social engagement. Dr Brent discussed with us the questions left to answer as a result of this research; these older females were still active and engaged with the group, but what were the consequences of age in relation to this interaction which meant they were received differently by their relatives?

To analyse the interaction between ageing and sociality from the opposite direction, Dr Brent now wanted to see whether the pace at which individuals age is affected by social processes. In the macaques, it as was hypothesised that more socially integrated females lived longer. In this study, as a proxy for social integration, the number of close relatives in the troop was recorded for each of the 276 females in the study. Dr Brent revealed to us that for ‘prime-aged females between the ages of 6 and 17, every relative added decreased the probability of dying the next year by 2.3 %’. Interestingly, this was not the same for older females, where their level of social integration had no effect on their survival the next year. Again, this poses the question of why; as Dr Brent proposed, “do females have an alternative route to success?’.

The lecture was rounded off with an exclusive look at some of Dr Brent’s unpublished research and a first look at the new projects she has coming up, including investigating the possible evolutionary drivers behind sociality and ageing. The audience was also left with some questions to think about regarding the physiology behind ageing in a social world. Do all tissues age at the same pace? Are they equivalently impacted by sociality? And is this ageing the same for males and females? While ageing may be the focus of this field, it is young in its development and there are many exciting questions yet to be answered.

Written by Esme Hedley, Biology (BSc)

One of the frontiers in the UK, Dr. Paul Jepson outlined his journey engaging with the process of rewilding, beginning in 2005, when he heard about work being undertaken in the Netherlands.

Rewilding is the process of restoring ecosystem dynamics and function at various levels; it can be condensed into the ‘3 C’s’;

1. Securing core areas
2. Connecting these core areas
3. Re-introducing large carnivores

The loss of micro-habitat diversity due to the reduction of megafauna and large herbivores brings into focus the severe need to restore ecosystem function around the world on a large scale. Rewilding has been suggested as a solution to this. It aims to generate new natures that are ecologically richer than those before. As Paul said – it’s all about moving forward.

The study and application of rewilding has become much more prevalent in recent years with many articles and scientific papers being released on the subject. Despite being still in its relative infancy, there are many current cases of rewilding such as species reintroduction in the UK and the development of hybrid ecosystems in Australia.

The development of rewilding may signify a new environmental narrative in which people can readily challenge governments to take actions to change the recovery and wellness in nature to surpass previous standards. Dr. Jepson’s narrative structure of ‘Recoverable Earth’, in which recovery of the environment was the final outcome, was a refreshing notion.

Paul spoke briefly about the rewilding poster child project in Nijmegen in the Netherlands:

This project was highly successful and created a huge diversity of habitats within the small area which boosted the public opinion of the scheme. Dr Jepson also spoke about the vast socio-economic benefits of rewilding with its positive impact on property values, life quality and job opportunities in Nijmegen.

Controversies surrounding rewilding included the mention of the starvation of large herbivores that were reintroduced into the Oostvaarderplassen nature reserve and the consequent public outrage in the Netherlands. Paul spoke about ‘kept wild’ animals in rewilding schemes as wild animals under management by humans (as is the norm in Southern Africa) being the most viable way to tackle current restrictions faced by domesticated animal laws; such the legal requirement to remove a carcass of a domestic animal within 3 days of death. This restricts the processes associated with carcass and scavenger ecology, which in turn restricts trophic expansion within the rewilding environment. De-domestication policies are being thought up that will enable rewilding schemes to have maximum success in trophic expansion through carcasses of ‘kept wild’ animals being reintroduced into food chains.

The seminar was closed with some thoughts on the future of rewilding. Paul spoke about the exciting future projects that rewilding has to offer and the likelihood that they will interlink with advances in technologies within the ever-expanding areas of biological sciences.

Written by Nina Blampied (year 2 Zoology BSc)

This Monday Professor Tracy Lawson from the University of Essex talked to students and academic staff in Bristol about her last findings in the survey of stomata behaviour as a response to different environmental stimuli.

This Monday, Professor Tracy Lawson from the School of Biological Sciences of the University of Essex talked to students and academic staff of the LSB in Bristol about her last findings in the survey of stomatal behaviour as a response to different environmental stimuli. During the last 6 years, she and the members of her lab have been working on stomata, water assimilation rates and CO2 gain, the speed of response of stomata in different light conditions, and the importance of studying this topic according to current and future global environmental conditions such as increases in temperatures worldwide, more food production using less land, changing rainfall patterns and lack of water sources for demanding irrigation crops.

During the first part of her talk, Professor Lawson talked about how different plants have different patterns of stomatal behaviour and how these respond differently according to plant phenotype and environmental conditions. Just to mention an example, rice can get a maximum carbon assimilation rate of 95% in only 10 minutes in comparison to Ginkgo biloba that takes one hour to reach a similar rate.

To know more about how plants respond to light fluctuations and climate, Professor Lawson mimicked natural fluctuations in light over a diurnal period to examine the effect on the photosynthetic processes and growth of Arabidopsis (Arabidopsis thaliana). She compared the plant’s behaviour under square wave light and fluctuating light conditions. Under the first treatment, plants responded with thicker leaves, more photosynthetic efficiency, better leaf structure and more proteins associated with electron transport. Plants under the second treatment produced thinner leaves, lower light absorption and slower growth. Under both conditions, plants maintained similar photosynthetic rates.

However, these results highlight that there is a negative feedback control of photosynthesis resulting in a decrease of diurnal carbon assimilation under fluctuating light conditions and that plants under square wave light fail as predictors of performance under realistic light regimes.

The following part of her talk was about the impact of dynamic growth light on stomatal acclimation and behaviour. Professor Lawson assessed the impact of growth light regime on stomatal acclimation and gas exchange growing Arabidopsis plants in three different lighting regimes:

1. with the same average daily intensity,
2. fluctuating with a fixed pattern of light, fluctuating with a randomized pattern of light (sinusoidal), and non-fluctuating (square wave).

With this experiment she and her research team demonstrated that g_s (stomatal conductance to water vapour) acclimation is influenced by pattern and intensity of light, modifying the stomatal kinetics at different times of the day and resulting in differences in the rapidity and magnitude of the g_s response. They quantified the response to a signal that uncouples variation in CO2 assimilation and g_s over most of the diurnal period. This can be translated as 25% water loss during the day without CO2 assimilation. The g_s response can be characterized by a Gaussian element when incorporated into the Ball-Berry model to predict the g_s in a dynamic environment.

Professor Lawson concluded that acclimation of g_s to light could be an important strategy for maintaining carbon fixation and overall plant water status and should be considered to infer responses of crops under field conditions.

Written by Carlos Gracida Juarez (Biological Sciences PhD)

What killed over 200,000 saiga antelopes in Kazakhstan in 2015 and should it change how we think of wildlife disease?

As a species that inhabits vast regions of the Kazakhstan steppe and maintains one of the most magnificent migratory patterns in the world, it is no wonder that the mass mortality event of 2015 that killed over 200,000 saiga antelope became a global cause for concern.

In his seminar, Eric Morgan, a Professor at the School of Biological Sciences at Queen’s University Belfast, outlined the scientific response to such a mass mortality event, placing particular emphasis on the challenges he and his research team faced in the identification of the causal agent.

Saiga antelope, distinct due to their bulbous nose, roam the planes of Kazakhstan, migrating vast distances from winter to summer to aid survival in harsh environmental conditions. Once abundant, the species has experienced a series of population crashes since the collapse of communism due to a corresponding crash in livestock numbers, resulting in an increase in hunting.

Due to their complex migratory patterns, the saiga antelope is difficult to conserve, therefore mobile nature reserves were constructed by local authorities in response to their decline. This resulted in significant population growth, making the initiative “a great conservation success story”, as described by Eric.

However, the story doesn’t end there. In 2015 Richard Kock, Professor of wildlife health and emerging diseases at the Royal Veterinary College in London, discovered a vast graveyard of saiga antelope that had aggregated in central Kazakhstan to calve.

As a keystone species, this mass mortality event attracted a flurry of media attention and demanded urgent answers as to what had caused so many saiga antelope to die over a minute timescale. A meeting hosted by the UN resulted in the construction of a core research team, of which Eric Morgan was a key member.

Having never seen anything of this nature before, Eric went on to explain some of the atypical features of the scene that stumped researchers, such as even spacing of carcases, indicating an almost synchronised death of antelopes at the time of calving. Additionally, dead calves were found with their stomachs full, which is unusual as orphaned calves typically die of starvation. Therefore, this indicated to the research team that whatever had killed the adults had been passed to the offspring during feeding.

Symptoms included weakness, diarrhoea, respiratory difficulties and internal haemorrhages. Eric described the project as uncomfortable and difficult to be involved in not only due to the tragedy but due to the lack of time to respond, stating that “it was so up in the air”. The research team, therefore, were denied the time to generate and develop full hypotheses, finding themselves testing hunches, not factors. A working hypothesis table was constructed, detailing circumstantial causes rated from high to low probability. This table can be found supplementary to Eric’s paper.

The team ruled out many bacteria and viruses along with heavy metals as causal factors. A laugh was shared as Eric displayed a picture of his arm covered in mosquitoes, explaining how he had to let day-feeding mosquitoes land on him so that they could be picked off and sampled to rule out a vector-borne disease.

Finally, a diagnosis of Pasturella multocida was made, again puzzling the research team in that the bacteria is very common in the tonsils of carrier animals, so why doesn’t it cause a mortality every year? A factor within the saiga population must have been changing for bacteria carried in the tonsils to suddenly begin to invade the rest of the body. So far, further research does not show any differences between bacteria that breach the intestinal mucosa and that carried on the tonsils.

Eric continued by highlighting other interacting factors that may form additional pieces of the puzzle such as climate and parasite invasion. Climatic data at the time of past die-offs was collected and a principal component analysis developed. It was concluded that past die-offs had climatic factors in common, such as above 80% humidity and greater precipitation. Eric described this as a ‘climatic

signature’ but, highlighted that the link is weak as it is difficult to associate something out of the ordinary, a mass mortality event, with a variable factor such as climate.
But how do parasites enter the picture? “Humble gut-worms” stated Eric. Parasites invade the intestinal mucosa having dramatic effects on protein metabolism, and the effects may be accelerated during pregnancy. During late pregnancy and early-lactation, the mother directs proteins towards the developing calve, therefore is immunosuppressed and subsequently more vulnerable to bacterial infection.

Eric concluded by stating the team have only got so far in making definitive conclusions and that research is still ongoing. He commented that he is very pleased to have been involved in “a real conundrum” and described the experience as “most satisfying”.
It is possible that nothing can be done to prevent mass mortality events like this from affecting the saiga antelopes in the future. Therefore, research must focus on ways to develop populations large enough to “survive the hit”. However, it is important to acknowledge that this is relevant beyond the saiga system. Climate change is having a profound effect on host susceptibility and virulence. Adaptation to new conditions may be possible however room for manoeuvre is required. Eric stated “Leave parasites alone as they are part of the natural system? Maybe we cannot think like that anymore”.

The lecture was rounded off with a couple of questions, with one audience member enquiring as to whether the research team sought to treat any of the antelopes to try and increase the population back up to a sustainable level. Eric replied by stating “there is no time to intervene in something of this scale and would you want to?” He explained that the knee-jerk reaction may be to start feeding the saiga population hay and pasture, but that may lead to population aggregation around the food source and disease spread. “You have to think very carefully before you intervene in natural systems”.

Written by Beth Harris (year 3 Biology MSci)