A ‘ribbeting’ new paper – Poison frog cannibals

Spotted Thighed Poison Frog
An adult male brilliant-thighed poison frogs Allobates femoralis (Image courtesy of Matt Cage, Amazon Eco-tours).

For those of you that know me personally you’ll understand how I’ve always had a fascination with Herpetology, so when perusing the literature I couldn’t help but read the newly published study by Ringler et al. (2017). The paper broadens our ever-changing understanding of parental care in animals specifically the roles of complex behaviours such as infanticide and the care of non-related offspring. These behaviours are well documented in so called ‘higher’ vertebrates such as birds and mammals but until now nobody has taken a dive into the world of amphibians when evaluating these traits.

Infanticide is the intentional killing of infants often those that are related to the killer. This process is often deemed to be a sexually selected for trait and as a way of males to gain increased access to female mating partners. However males that have this cannibalistic streak must take great care in avoiding their own offspring in the process. Ringler et al. (2017), shows that male brilliant-thighed poison frogs Allobates femoralis (Dendrobatidae, Aromobatinae) adjust their parental responses for care and infanticide towards unrelated clutches based upon their territorial statuses. Males were immediately switching to cannibalism upon relocation. Could this mean care and cannibalism are antagonistically linked? Glad I’m not a frog to be honest!

So what even is an Allobates femoralis?

Well it’s a small colourful frog from the Dendrobatidae family that includes a number of toxic frogs originating in South America. Parental care by one or both sexes is considered a synapomorphy of this entire family. Allobates femoralis males are highly territorial despite only being the size of a two pence piece. Males advertise via calls to make females aware of their territory and to ward off other potential intruders, who are physically attacked by the territory holder (Narins et al., 2003). In what can only be described as miniature wrestling matches that can last up to 15 minutes. Females however are highly promiscuous moving between male territories and providing no parental care, merely just their eggs to be fertilised in ephemeral pools.

After three weeks of development the male will transport newly hatched tadpoles on his back to water bodies often outside his territory. Some males have been recorded to travel up to 100m, which is approximately 5000 times the length of their bodies! Quite a feat while carrying your offspring on your back (Pašukonis et al., 2014). Courtship, mating, and terrestrial oviposition take place in the leaf litter inside the male’s territory. It is therefore a prerequisite for male reproductive success. This explains the strong competition for territory but not the need for infanticide.

Allobates-femoralis with tadpoles
A male Allobates femoralis carries his tadpoles on his back in search of a new home for their development from tadpole to frog (Image courtesy of Seabird McKeon, Smithsonian).

So what did the study entail?

The study is based on manipulation of territorial status of males to induce ‘takeover’ behaviour and ‘resident’ behaviour. These experiments took place ex- situ in a lab-based study using a total of 20 males that were known to have sired offspring. Takeover males (N=10) were transferred from their home terraria into novel empty terraria. Resident males (N=10) were then captured and returned to their home terraria after the same handling procedure given to the takeover group. This helped to eliminate any effects of being handled. In both trials unrelated clutches of developing conspecifics were places in the terraria before the males were released (Fig 1). All trials were then filmed and the occurrence and frequency of cannibalism along with tadpole transport to pools was recorded.

Dart frog diagram
Figure 1: A – 10 males were returned to their own terrarium (“Resident”). B – The other 10 males was transferred to a new unoccupied terrarium (“Takeover”). In both  treatments an unrelated clutches of conspecifics was placed inside the tank before re-release (Image courtesy of Nadja Kavcik-Graumann and Andrius Pašukonis).

What did they find out?

Well it appeared that significantly more takeover males than residents were cannibalistic to unrelated clutches. In fact all 10 males that took new territory consumed the developing embryos of unrelated conspecifics compared with only 2 resident males (Fig 2A). Takeover males also fed more often and consumed more tadpoles (Fig 2B + 2C). Resident males however transported more tadpoles to water bodies with 8 out of 10 males transporting tadpoles compared to only 2 takeover males (Fig 2A). All these results point to a common trend that there are strongly differing parental decisions linked directly to an individual’s territory status.

Dart frog graphs
Figure 2: A – Residents’ mainly responded using parental care, however all ‘takeover’ males preyed on the clutches (Fisher Exact test, P < 0.001) . B – The frequency of cannibalistic events (median t/r = 6/0; Mann-Whitney U-test, U = 5.5, P < 0.001) and C – the total number of tadpoles consumed were significantly higher in ‘takeover’ males (median t/r = 5/0; Mann-Whitney U-test, U = 4.5,  P < 0.001). (Image courtesy of Ringler et al., 2017).

 

It seems that A. femoralis territory holders follow a very simple decision-making rule ‘care for any clutch inside my territory’, but ‘cannibalism’ is the way to go when taking over a new territory. This suggests that this context-dependent behavioural switch between infanticide and parental care is likely to be adaptive. It effectively allocates parental effort while minimising the risk for parental errors at a very low cognitive cost. To put it very simply the frog thinks ‘why not eat your neighbours babies because it’s too much effort to look after them and your own at the same time’. Plus it’s a good source of nutrients compared to eating insects all day.

It can also act as an antagonistic backup strategy as it is difficult for a frog to tell if the embryos are his or not and can only decide through memory. This is supported by similar behaviour in a species of harvestman and recently also for the plainfin midshipman fish which cannibalises foreign eggs after nest takeover (Bose et al., 2014) In A. femoralis the likelihood for males to encounter foreign clutches naturally inside their own territory is very uncommon due to their defensive nature. It is therefore logical for resident males to take care of all offspring in their patch.

These findings demonstrate that parental decision-making incorporating an adaptable shift between care and infanticide to avoid misdirected care can evolve in the absence of group living. This behaviour can also clearly evolve in species with comparatively simple brain organisations.

But how is this beneficial for Science?

Ringler et al.’s (2017) results should now prompt a reconsideration of evolutionary and causal aspects of parental decision making, as we currently understand it. The study is suggesting that selective infanticide of unrelated young may generally become adaptive when the risks and costs of misdirected care are high. This seems very reasonable in my eyes and further consideration should be taken to address these predictions. This could be achieved by further assessments between diverse animal taxa, with different social structures and parental systems. It would help us further understand how different parental strategies are promoted and maintained over evolutionary time.

Coupled with recent research on mice it has emphasised that feeding and parental behaviours might be regulated antagonistically via a common physiological pathway (O’Rourke and Renn, 2015). This fascinating paper has sparked many ideas into investigating the links between neuronal and hormonal activity in territoriality, mating, feeding, and parental care.

All of this because of one little frog! Sit back and think about that for a second!

By Joe Gilmour

References

Bose, A., Cogliati, K., Howe, H. and Balshine, S. (2014). Factors influencing cannibalism in the plainfin midshipman fish. Animal Behaviour, 96, pp.159-166.

Narins, P., Hodl, W. and Grabul, D. (2003). Bimodal signal requisite for agonistic behavior in a dart-poison frog, Epipedobates femoralis. Proceedings of the National Academy of Sciences, 100(2), pp.577-580.

O’Rourke, C. and Renn, S. (2015). Integrating adaptive trade-offs between parental care and feeding regulation. Current Opinion in Behavioral Sciences, 6, pp.160-167.

Pasukonis, A., Warrington, I., Ringler, M. and Hodl, W. (2014). Poison frogs rely on experience to find the way home in the rainforest. Biology Letters, 10(11), pp.20140642-20140642.

Ringler, E., Barbara Beck, K., Weinlein, S., Huber, L. and Ringler, M. (2017). Adopt, ignore, or kill? Male poison frogs adjust parental decisions according to their territorial status. Scientific Reports, 7, p.43544.

 

 

 

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Chimpanzees observed using tools like never before

Earlier this year, chimpanzees were observed using tools in an incredible way in a paper published in Nature Scientific Reports (van Leeuwen et al., 2017). After one of a group of chimpanzees died, a female chimpanzee sat by the dead body and started to clean the deceased male’s teeth with a piece of firm grass. This observation may provide clues to how humans developed our rituals and practices after the death of a loved one.

The behaviour was observed at the Chimfunshi Wildlife Orphanage Trust in Zambia by scientists from the University of St. Andrews. It was exhibited by a female chimpanzee named Noel who sat by the body of a young male named Thomas. When Thomas died, most of the group of chimpanzees visited his corpse at least once. Food was used to lure the chimpanzees away from the body, but Noel stayed by the body and cleaned his teeth with her daughter Nina watching on. Thomas was a younger member of the group and had been adopted by Noel as his mother had died four years earlier.

chimo figures
Images of Noel tending to Thomas’ corpse.

How did they observe the behaviour?

The group of scientists had been following the group for 4 months before this incident. When they discovered the dead body, they immediately started filming it with two cameras to understand the chimpanzees’ response to the body. The video in question is a 20-minute clip that shows the behaviour. As well as their own 4 months of observing the group beforehand, the scientists also conducted interviews with some caregivers to the chimpanzees who had known them for over 4 years. This helped to understand the relationships in more detail to further explain what they saw.

How have animals previously been observed responding to deaths?

Many animals show little or no reaction to another individual’s death. However, African elephants (Loxodonta africana) show great attention to dead bodies of their own species and individuals close to death, a behaviour which is hardly seen in other animals (Douglas-Hamilton et al., 2006). Furthermore, leopards (Panthera pardus) have been observed grooming and carrying stillborn infants but these have been isolated incidents so it is hard to tell conclusively how significant the behaviour is.

Primates are more likely to respond to a conspecific death, especially the Great Apes. Prior to this study, chimpanzees have been seen to pay great attention and care to dying individuals in their social group such as grooming and vocalising (Teleki, 1973). There is thought to be a link between recognising the death of a close individual and having a sense of self, so going through a process of seemingly mourning demonstrates a certain extent of emotional intelligence and social cognition.

What does this all mean?

The behaviour observed by the female chimpanzee Noel is potentially significant for a number of reasons. Firstly, it has never been seen before in any non-human species so it is a unique event. Using tools for in social behaviour is rare, with a few descriptions of dental cleaning using tools with living chimpanzees having been seen before (McGrew & Tutin, 1972). However, in the total of 8000 hours of observation with this group of chimpanzees, this behaviour had not been seen at all so it was a totally unique action irrespective of the chimpanzee being living or dead.

tool close
A close-up of the dexterity shown by Noel while cleaning Thomas’ teeth.

An important element to consider is the prior relationship that the two chimpanzees had before Thomas’ death – Noel had seemingly adopted Thomas as her own son after his mother passed away. This bond that they had developed appeared to last once he had died showing the strength of relationships that the chimpanzees built over their lives. The way that chimpanzees generally treat corpses to our best knowledge is with care and in a meaningful way, and this behaviour shown by Noel seems to exemplify this. Furthermore, the caretakers were presenting high-quality food to the chimpanzees at the time, but Noel stayed with Thomas’ corpse rather than leave the area in favour of the food. Another possible explanation for the observed behaviour is that she may have been expressing curiosity and wanting to learn about death through the situation that had occurred (Cronin et al., 2011).

Are we reading too much into the behaviour?

It is important to remember that this is an isolated incident making it difficult to draw overarching conclusions. In general, anecdotal evidence must be treated with a sense of caution when trying to understand behaviour. Some members of the scientific community have been are sceptical about the interpretation of the actions of the chimpanzee. The University of Geneva’s Dr Thibaud Gruber says that the teeth cleaning process may have been an example of ‘social cleaning’ rather than ‘corpse cleaning’ as he claims we are unsure how much chimpanzees know about death. In addition, Professor Klaus Zuberbuehler of the University of St. Andrews, but not a part of the research group, says that Noel may not have understood that Thomas was dead and her actions may have been in response to him simply being motionless at that time.

Overall, I think that this behavioural observation shows us a fascinating response to a dead body and should serve as a reminder to us of how complex and intelligent chimpanzees really are. Demonstrating a unique behaviour like this seems very significant to me. In general, investigating different animals’ responses to the death of a conspecific is very interesting though we don’t really have access to many detailed accounts of this in a lot of species. Perhaps this study could lead the way in encouraging us to more closely observe this type of behaviour across more animals.

By Danny Estreich

This is a link to the video to see the incredible behaviour for yourself:

http://content.jwplatform.com/previews/VG0SWHBs-YtF6y0JQ

References

Cronin, K.A., Van Leeuwen, E.J., Mulenga, I.C. & Bodamer, M.D. 2011. Behavioral response of a chimpanzee mother toward her dead infant. American Journal of Primatology73(5), pp.415-421.

Douglas-Hamilton, I., Bhalla, S., Wittemyer, G. & Vollrath, F. 2006. Behavioural reactions of elephants towards a dying and deceased matriarch. Applied Animal Behaviour Science, 100(1-2), pp.87-102.

McGrew, W.C. & Tutin, C.E. 1972. Chimpanzee dentistry. The Journal of the American Dental Association85(6), pp.1198-1204.

Teleki, G. 1973. Group Response to the Accidental Death of a Chimpanzee in Gombe National Park, Tanzania. Folia Primatologica, 20(2-3), pp.81-94.

van Leeuwen, E.J., Cronin, K.A. & Haun, D.B. 2017. Tool use for corpse cleaning in chimpanzees. Scientific Reports7, p.44091.

Three’s a crowd

It has recently been announced that three parent babies could be born next year in the UK https://www.theguardian.com/science/2016/dec/15/three-parent-embryos-regulator-gives-green-light-to-uk-clinics. This is thanks to a new therapy which has been recently been introduced in the UK. The therapy is called mitochondrial replacement therapy. In this post, I shall attempt to explain more about this therapy as well as giving my views on the subject.

Mitochondria are an important part of the cell. This is because they produce energy which is used in the cell through a process known as oxidative phosphorylation. The mitochondria also contain DNA which is involved in synthesising proteins which help with the functioning of mitochondria as well as other functions in the cell. However sometimes this mitochondrial DNA may be faulty and can cause genetic diseases. The genetic diseases can cause health issues such as seizures, learning disabilities, deafness and blindness(https://www.action.org.uk/our-research/mitochondrial-diseases-developing-new-treatments-children-these-rare-and-sometimes-deva?gclid=CLWTsp2z3tICFUMo0wodaKkM7Q ).Genetic diseases from faulty mitochondrial DNA affect approximately 1 in 5000 people so is a problem which needs to be addressed(Sirrs et al, 2011).

Mitochondrial replacement therapy is a technique which attempts to treat these genetic diseases. The treatment works by replacing the mother’s faulty mitochondria in the embryo with healthy mitochondria. This means that embryos which have had this treatment will have DNA from three different parents. Only the mother’s mitochondria are replaced, as interestingly all human mitochondrial DNA is only inherited from the mother. There are two forms of mitochondrial replacement therapy: pronuclear transfer and maternal spindle transfer

Pronuclear transfer involves the manipulation of pronuclei in the mother’s and the donor’s embryos. A pronucleus is a nucleus of a gamete (Sperm or egg) during the process of fertilization, before the fusion of the nuclei but after the sperm has entered the ovum.Pronuclear transfer is a complex process (Figure 1) consisting of:

  • In Vitro fertilisation creates an embryo which has a nucleus containing parents nuclear material and mitochondria which have the faulty mitochondrial DNA
  • The two pronuclei are removed from the cell and the rest of the cell is discarded.
  • A second embryo is created from a donor female’s egg and either the same father’s sperm or a donor father’s sperm.
  • The second embryo also has its pronuclei removed. Except the embryo is kept and the pronuclei are discarded
  • The pronuclei from the first embryo are inserted into the embryo from the donor female
  • The embryo is then transferred back to the mother as it now contains healthy mitochondrial DNA

The process has been worked on since the 1990s when it was first attempted in mice. The first successfully transferred pronuclear DNA in humans by the scientists at Newcastle University in 2008. The growth of these embryos was stopped after five days for analysis.

egg

Figure 1. Pronuclear transfer. Image courtesy of  http://www.theguardian.com/science/2013/jun/28/uk-government-ivf-dna-three-people

I will not go into detail about this maternal spindle transfer as currently only pronuclear transfer is allowed. If you are interested in learning about this process you can read more about it here https://mitochondrialtransfer.wordpress.com/the-logistics/mitochondrial-replacement/maternal-spindle-transfer/.

The reason that pronuclear transfer is allowed and that maternal spindle transfer is not allowed is that only pronuclear transfer has been granted a licence by the Human Fertilisation and Embryology Authority (HFEA). The HFEA regulate the use of gametes and embryos in fertility treatment and research in the UK (http://www.hfea.gov.uk ) and have granted two-step licences to scientists at Newcastle University (Herbert & Turnbull, 2017). However, the treatment can only occur after patients have applied for treatment to and been approved by the HFEA. The regulations also mean that currently MRT can only be carried out in the UK at the Newcastle Fertility centre. However, it is hoped that this centre can use the treatment to treat up to 25 women a year. £8 million of funding has been supplied by NHS England for a five-year clinical trial. This shows that the treatment is under strict controls by the licensing authorities. This may be due to the ethical considerations surrounding the treatment.

Critics say that the technique may not entirely stop genetic diseases as some faulty mitochondria may be carried over into the child and even replicate in the developing embryo. Therefore, genetic diseases may not be completely eradicated by this treatment. My opinion on this criticism is that if the treatment poses no additional risk if faulty mitochondria are carried over into the child compared to not having treatment, then this should not be an issue. However, if there is an additional risk then the decision as to whether to undergo this treatment should be carefully considered by medical professionals.

Further criticism comes from the religious views that this treatment constitutes playing god. Or that this could be start of legalising more genetic treatments. This could have positive and negative effects. Genetic treatments are good if it is for treating disease. However, if it was taken to the extreme it could also lead to designer babies or a dystopian future were the genetic makeup of all individuals has been chosen to reduce mechanical and economic production, like in Aldous Huxley’s novel “Brave New World”. However, I don’t believe that it would ever be taken to this extreme in the UK. This is because of the number of regulating bodies we have in place to control which treatments can and can’t occur.

The final issue is with the donor mother. What is there future relationship with the child? After all they are contributing to the genetic makeup of the child. I think with this issue it should initially be the decision of the parents as to what the relationship is with the donor mother. However, as the child matures I think that they should get to choose for themselves what their relationship with the donor mother would be. This would mean that records and contact details would need to be kept regardless of what the parents think the relationship that the child has with the donor mother should be.

In conclusion, I believe that MRT is a great advance in the treatment of genetic diseases. As with everything in life there are ethical considerations which we should be aware of, which I have given my opinion on. However, it should be stated that I have only given my opinion and that the reader should search for other opinions on the subject and formulate your own opinions and the issue.

By Richard Coppins

References

Herbert, M. & Turnbull, D. Mitochondrial donation – clearing the final regulatory hurdle in the United Kingdom. The New England Journal of Medicine. 376: 171-173. DOI: 10.1056/NEJMcibr1615669

Sirrs, S., O’Riley, M., Lorne Clarke, M.D.C.M. and FCCMG, A.M., 2011. Primer on mitochondrial disease: Biochemistry, genetics, and epidemiology. depression500, p.70s.

https://www.action.org.uk/our-research/mitochondrial-diseases-developing-new-treatments-children-these-rare-and-sometimes-deva?gclid=CLWTsp2z3tICFUMo0wodaKkM7Q

http://www.hfea.gov.uk/

http://www.theguardian.com/science/2013/jun/28/uk-government-ivf-dna-three-people

https://mitochondrialtransfer.wordpress.com/the-logistics/mitochondrial-replacement/maternal-spindle-transfer/

Trumping on climate change

Unless you’ve been shut away from the world for the past three months, you will all have heard one of the most surprising events in United States history, the election of Donald Trump as the 45th president of the USA. Through the controversy, it’s clear that President Trump will have drastic impacts on lives of people throughout the world, but could this effect be more substantial than first thought?

trump 1
Photo credit: Huffington Post
Throughout campaigning, Donald Trump hasn’t been afraid (despite a barrage of opposition) to express his alternative views on climate change. Previously, climate change has been labelled as “the world’s greatest threat” by former US President, Barrack Obama. And evidence has suggested many potential effects ranging from severe weather conditions to mass extinctions.

Despite this, Trump has long disregarded climate change as hokum. And yes, he did once claim global warming was a hoax invented by the Chinese… Therefore, the question remains, now that Trump is in charge of the leading country tackling climate change, what will this presidents legacy of our world be?

china
The famous Trump Tweet claiming the Chinese made global warming up… Image Credit: PolitiFacts.
 

In-terms of policies concerning climate change, those that Trump has so far mentioned have been… Worrying, to say the least… Of particular interest, these policies include; the revitalisation of coal power, the removal of the Environmental Protection Agency (EPA), reversion of environmental regulations, cutting of climate change funding, and potentially the most devastating, pulling the United States out of the landmark Paris Climate Change deal.
 

Making coal great again!?

You don’t have to be a genius to realise that burning coal isn’t good for the world… Despite providing large amounts of energy, coal is responsible for tens of thousands of human deaths per year, often requires the destruction of habitats to mine, and creates copious amounts of greenhouse gases that fuel climate change. So the news that Trump aims to provide “trillions in new wealth” by reopening American coal mines is one that have environmentalists fuming.

In the speech (North Dakota, June 2016), without concern for climate change, Trump revealed energy plans aimed at providing millions of jobs throughout the U.S. by reopening coal mines. This was particularly targeting against Hilary Clinton, Trumps’ rival presidential candidate, who was concerned with increasing coal mining regulations in clean fuel policies, which would have led to the reduction of mining jobs.

 

coal
Photo credit: http://www.planetenergynews.com
If such a plan were to be used, then this would be “an enormous step backwards with huge health implications”, claims Kerry Emanuel, a climate change expert from Massachusetts Institute of Technology.  Alongside not pursuing ‘clean energy’, the burning of ‘the dirtiest fuel’ would release millions of tonnes of carbon dioxide, greatly influencing the effects of global warming. But how likely is this plan to actually go through?

Well it turns out, it’s actually not likely at all… Besides from environmental concerns, the truth is there is simply no demand for using coal anymore as natural gas is by far cheaper! So that’s strike one for Trump vs. Climate change!

 

Funding for the environment…

There has been much anticipation waiting for what the new Presidential administration has in store for the EPA, the agency dealing with everything from climate change research to pollution, and our answer may finally be here.

On the 16th of March, the White House announced the 2018 preliminary budget, and although the EPA hasn’t been totally removed as first thought, it has been on the funding chopping block.

 

epa_climate_change_deleted
Photo credit: http://www.alphr.com
On the document, it proposes that the EPA will experience a massive 31 percent loss in funding from $8.2B to $5.3B, resulting in a loss of 2,500 jobs and the scrapping of many schemes aimed at reducing greenhouse gas emissions. Instead, the EPA, now run by climate change denialist Scott Pruitt, has been directed to “focus on clean water, clean air, and other core responsibilities, rather than activities not required by law”.

These reductions in EPA funds, in part, are required to make way for Trumps increased spending in other areas, including a $54B increase in U.S. military defence.

Of schemes experiencing severe funding cuts, those aimed at cutting greenhouse emissions have been cut by 70% ($95M to $29M), and the Office of Research and Development may lose 42% of funds, with some of their projects being scrapped entirely. For example, the ‘contribution to the U.S. Global Change Research’, a climate change scheme produced by President George Bush in 1989 is set to have its’ funding removed.

The good news is that these funds aren’t finalised, and any changes would have to be codified by congressional appropriations process, during which, they would likely face severe opposition from law makers. So although funds dealing with climate change may look bleak, all is not yet loss.

 

The 2015 Paris Climate Change deal

Perhaps a leading concern for climate change is the potential for Trump to remove the U.S. from the landmark 2015 Paris Climate Change deal.

The deal, which was signed by 196 countries, pledged the countries to reducing the release of greenhouse gases, reducing the use of fossil fuels, and keeping global temperatures below a 2°C increase over the next two decades.

As with anything dealing with climate change, Trump isn’t happy with it, and considers the deal a way for “Foreign Bureaucrats” to control how much energy the U.S. consumes (even though each country controls how much fuel usage they aim to reduce…). In classic Trump fashion, he therefore aims to remove the U.S. from the deal. This removal actually looks like will be happening very soon, with Myron Ebell, leader of the EPA transition team, quoting that the U.S. will “definitely be pulling out of Paris climate change deal”

The deal was the first real agreement throughout the United Nations into tackling global warming on a large scale, and the removal of such a big player from this deal could be catastrophic, possibly causing others such as China to also remove themselves.

 

Conclusion

These policies will certainly save/make America money, but at what cost? Experts have predicted that if Trumps’ policies go into place, then the earth’s temperature will continue rising at an alarming rate. Some have even suggested under Trumps presidency, the U.S. will pump a billion more tonnes carbon into the atmosphere compared to Clinton predicted outlet.

 

trump graph
Image credit: Lux Research Inc.
So there you go, Trump promised a United States less concerned with the Earths’ climate, and thus far, he appears he seems to be delivering… The only true way to fight against this is for the rest of the world to pick up the pieces, and hope that their climate change efforts are enough to steady the already rapidly escalating change in climate.
By Lewis Dolman 

 

If you’re interested in taking a look at Trumps’ new funding:

https://www.washingtonpost.com/graphics/politics/trump-presidential-budget-2018-proposal/?utm_term=.6fff31dc9001

 

Is it a fish? No it’s a carrier bag

Ocean boat rubbish
An attempt to remove plastic from the Ocean, the surface is so densely packed it is difficult to see the water (Image courtesy of Onegreenplanet.org).

It certainly doesn’t take a genius to see that our consumption on Earth is unsustainable. A great cause for concern currently lies in the vast amount of disposable plastics making their way into the oceans and water bodies of the world. The United Nations claim that between 2004 and 2014 plastic production rose by 38% and is growing at a faster rate each year. Currently as a planet we are producing approximately 300 million tonnes of plastic per year, half of which is disposable and never used again. Under this great act of negligence more than 8 million tonnes of this plastic is directly dumped into the oceans each year (Plasticoceans.org). It has become more prevalent in the media in recent months due to health and environmental damage and risk it is beginning to cause (Smillie, 2017).

Plastic has many properties that make it ideal for a vast amount of application such as its versatility and ease of production. The fact it is so cheap in the developing world with few means to recycle it, these qualities are also its worst and have lead to such a large environmental issue. In 2016 the Ellen MacArthur Foundation estimated that by 2050 there’d be a larger volume if accumulated plastics in the worlds ocean than the volume of fish. The great Pacific plastic raft is a major contributor to this statistic as plastic and debris become trapped in its gyre and accumulate over vast areas of Open Ocean. The UN environmental programme is worried that if current growth rates continue it’ll become visible from space (Figure 1). The slow degradation of these plastics is now of primary concern.

trash-vortex map
Figure 1: A map of the North Pacific gyre showing how vast quantities of plastic and rubbish are caught in the currents and beginning to accumulate (Image courtesy of Haltonrecycles).

Microplastics, microbeads, rubbers and nurdles…

Microplastics incorporate a number of different sources including microbeads (cosmetics), small packaging plastic pellets (nurdles) and microfibres from shredded rubber or clothing all of which must be 5mm to 10nm in size. Although there is little biodegrading occurring, larger pieces of plastic often photo-degrade from UV light exposure into these small pieces. These tiny pieces of plastic are what enter the food chain often mistaken for food by fish in appearance and also the fact that plastic attracts thin layer of marine algae that in turn attract fish, the smell is also believed to attract sea birds. In 2015, a team at the Plymouth Marine Laboratory found zooplankton directly feeding on microplastics, which came as quite a shock and can be seen in (Figure 2).These microscopic organisms form a vital part of the food chain and the worry is plastic maybe getting inside most sea life (Barnes et al., 2009). Figure 3 also shows the distribution of plastic deposits within these plankton populations around the United Kingdom.

plastic plankton
Figure 2: A copepod and diatom next to a piece of micro plastic (Image courtesy of SAHFOS, 2008).
uk plastic map
Figure 3: Map of the UK showing the distribution of plankton micro plastic deposits between 2004-2009 (Image courtesy of Barnes et al., 2009)

 

Not only is it polluting our oceans, endangering wildlife and the ecosystem it is starting to enter our food chain. This may possess potential risks of eating shellfish and seafood. Researches at Ghent University in Belgium calculated that European shellfish lovers are consuming 11,000 pieces of plastic in their mussels each year, only 1% of which is absorbed but the threat still remains if it were to build up built this remains unknown (Van Cauwenberghe and Janssen, 2014). Here in Britain the threat is very much real as it was reported that plastic was found in a third of UK-caught fish, including cod, haddock, mackerel and shellfish (Barnes et al., 2009).

What can we do?

There will never be an easy solution to this global problem but one of the first steps is to make people aware of the oceans condition. Plastic Oceans released a documentary film in order to increase public awareness. Not only education but also action is required in the formation of more responsible and sustainable plastic production. The development of new technology such as ocean filtration systems and dredging of floating waste may be required to mitigate and improve upon this issue. Governments in Europe are starting to wake up to the cause of these pollutants but things may be different for the UK as it begins the process to leave the EU. I feel that our oceans are often neglected and there isn’t enough media coverage. An increased feel of responsibility may drive people to a more sustainable and responsible life. Regarding seafood and microplastic consumption the issues will only continue to worsen until pollution levels drop.

By Joe Gilmour

 

If you’re interested in finding out more about the plastic oceans film then here is the link: http://www.plasticoceans.org/about-film/

 

References

Barnes, D., Galgani, F., Thompson, R. and Barlaz, M. (2009). Accumulation and fragmentation of plastic debris in global environments. Philosophical Transactions of the Royal Society B: Biological Sciences, 364(1526), pp.1985-1998.

Smillie, S. (2017). From sea to plate: how plastic got into our fish. [online] the Guardian. Available at: https://www.theguardian.com/lifeandstyle/2017/feb/14/sea-to-plate-plastic-got-into-fish [Accessed 5 Mar. 2017].

Van Cauwenberghe, L. and Janssen, C. (2014). Microplastics in bivalves cultured for human consumption. Environmental Pollution, 193, pp.65-70.

 

 

 

 

 

A blast from the past: How ancient human populations affect today’s forests

Humans have relied upon amazon forests for thousands of years for food and shelter (Clement et al. 2010). The recent impacts, such as deforestation, upon these forests can be clearly seen. However, a recent publication by Levis et al. (2017) suggests that the historic human impact on amazon forests can still be seen today. In this blog post I shall comment upon this publication and explain why it is important.

The study by Levis et al. (2017) looked at 4962 tree species in the amazon. To measure the presence and abundance of each of these species, Levis et al. (2017) used 1170 forest plots of the amazon from the Amazon Tree Diversity Network. This network is a formed by a collection of scientists who collect and share information about palms and trees in the amazon. This highlights how new findings can be made through the sharing of data between scientists.

Levis et al, (2017) also looked at archaeological sites and other environmental data. The distribution of the tree species was compared to the locations of 3795 known pre-Columbian archaeological sites and potential settlements. From this data, Levis et al. (2017) could infer which species would have been harvested and grown by these ancient communities.

The study by Levis et al, (2017) highlighted the difference between domesticated and non-domesticated trees and palms. The domesticated plants were believed to be domesticated by pre-Columbian people. Domesticated woody species included Brazil nuts, Bertholletia excelsia, and the Amazon tree grape, Porouma cecropiifolia. It was shown that domesticated were five times more likely to be over represented in this region than non-domesticated plants. This is likely to be due to the influence of the pre-Columbian people as it was shown that the domesticated trees were often found in clusters around previous known settlements of pre-Columbian people. Levis et al. (2017) found that 20 of the 85 domesticated woody species in were over represented, also known as hyperdominant, in the region. This is interesting for two reasons. Firstly, it shows the long-term impact humans have on the planet, like the butterfly effect. Secondly, scientists may be able to predict locations of other unknown settlements based upon the composition of trees found in this forest or other forests.

tree

Figure 1. Brazil nut tree. Image courtesy of https://clipartfest.com/categories/view/b043f0ceceee5a207c4397ca47d5a97f00823165/rainforest-brazil-nut-tree-clipart.html

Environmental conditions also contributed to the distribution of plant species. Environmental conditions included the seed dispersal rates by animals such as primates and soil conditions. In general, environmental conditions were believed to cause around 30% of the distribution of domesticated species whereas the location of settlements contributed 20% of the distribution of domesticated species. However, in areas with larger settlements, such as in southwestern Amazon, 30% of the distribution of domesticated species came from the location of settlements and less than 10% of the distribution was linked to the environmental conditions in the area.

There should also be some scepticism towards the results produced. This is because humans tend to show repeatability when choosing were to settle. This could mean that modern settlements have formed where ancient settlements previously stood. The example that the Levis et al, (2017) gave was the plantation of cocoa trees in Amazonia by Spanish and Portuguese colonisers in the late 17th century (Alden, 1976). These plantations would’ve occurred in areas where previous settlements had been thus influences the distribution of species found in that area but the introduction of cocoa plants was not caused by the ancient settlments. Therefore it is possible that modern populations are influencing the distribution of plant species seen in the forest.

Further potential criticism arises from human actions leading to the growth of domestic species through indirect methods. For example, trees may recolonise an area after the settlement is deserted. This was seen in the re-colonisation of Mayan sites in Central America by Brosimum trees. The presence of the trees in that area was not originally believed to be due to recolonization but was believed to be because the Mayans had planted them there, however this is now widely discredited (Peters, 1983). So the distributions seen by Levis et al, (2017) may be due to recolonization rather than direct human action.

This paper by Levis et al, (2017) has shown how humans have made an impact upon forest communities and will continue to do so. It also gives us an additional insights into the lifestyle and location of ancient settlements. These findings could be useful for making conservation decisions and finding more ancient settlements in other forests by following similar patterns.

By Richard Coppins

References

Alden, D., 1976. The significance of cacao production in the Amazon region during the late colonial period: An essay in comparative economic history. Proceedings of the American Philosophical Society120(2), pp.103-135.

Clement, C.R., de Cristo-Araújo, M., Coppens D’Eeckenbrugge, G., Alves Pereira, A. and Picanço-Rodrigues, D., 2010. Origin and domestication of native Amazonian crops. Diversity2(1), pp.72-106.

Levis, C., Costa, F.R., Bongers, F., Peña-Claros, M., Clement, C.R., Junqueira, A.B., Neves, E.G., Tamanaha, E.K., Figueiredo, F.O., Salomão, R.P. and Castilho, C.V., 2017. Persistent effects of pre-Columbian plant domestication on Amazonian forest composition. Science355(6328), pp.925-931.

Peters, C.M. 1983.Observations on Maya subsistence and the ecology of a tropical tree American Antiquity 48, 610–615

https://clipartfest.com/categories/view/b043f0ceceee5a207c4397ca47d5a97f00823165/rainforest-brazil-nut-tree-clipart.html

Project Stickleback

Before discussing my project, some background information and key concepts relating to my project shall be explained. The two main concepts are natural selection and adaptive radiation.

Natural selection is the process by which organisms that are better adapted to their environment, will be more likely to survive and reproduce. Organisms are better adapted to their environment through having traits, which provides them with a higher fitness. This leads to future generations of the population having more individuals with the favourable traits, because the traits are inheritable. Therefore the process of natural selection leads to the evolution of a species. (http://evolution.berkeley.edu/evolibrary/article/evo_25). This means that natural selection may be shown by how populations change with time. This change shall be used as the basis of my project (Figures 1 and 2).

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Figure 1. This figure shows the change in the distribution of continuous traits of a population with time. The red line represents a theoretical population and the blue line represents the population after some time has passed. This new population may consist of a subset of the original population or offspring from the previous generation or a combination of both. This shows that the later population has individuals that have larger body length compared to trait 1 than the earlier population. Therefore, it may have been favourable to have a smaller trait 1 compared to body length in the initial population.

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Figure 2. Change in the distribution of discrete traits with time. The red lines represent a theoretical population and the blue lines represent the same population after time has passed. The blue line may contain a subset of individuals from the initial population, it may contain offspring from the initial population or a combination of both options. This graph shows that the mean of trait 1 is larger in the later populations. This shows that having a larger trait 1 may have been favourable in the initial population.

Adaptive radiation leads to ecological and phenotypic diversity in a lineage which is rapidly multiplying through evolution (Schluter, 2000). The large diversity in the lineage produced in a short time, means that the process of adaptive radiation is useful for studying evolution on much shorter timescales. Adaptive radiation is seen in many species such as the Galapagos finches. https://www.britannica.com/science/adaptive-radiation.

Now that you have some background knowledge of my project, we can review the projects aims. The main aim is to examine how the strength of natural selection on multiple phenotypic traits varies with different predation intensities. This means that we must examine whether there is evidence of natural selection on multiple phenotypic traits under different predation intensities. This is important to try and understand because not a lot is known about the selective agents that cause evolution (MacColl, 2011). Having more knowledge about selective agents may be helpful when predicting the effects of climate change upon species and helping with conservation efforts.

Three-spined stickleback, Gasterosteus aculeatus, populations of three lochs in North Uist, Scotland are the study species which are being used to attempt to achieve the objectives of this study. This is because the populations exhibit a large amount of phenotypic diversity both between and within lochs. The phenotypic diversity has been generated due to the fact that each of the lochs has a different set of environmental factors. This means I may be able to correlate the strength of natural selection on multiple phenotypic traits with environmental factors such as predation intensity.

To measure how natural selection on phenotypic traits varies under different selection pressures, I am looking at how the distribution of phenotypic traits found in the different lochs changes over the course of a year. This is achieved through taking photographs of stickleback, which have been euthanized using MS 222 and stained using alizarin red (Figure 1). The photographs were then analysed using imagej. The traits which were measured were armour traits (Figure 3). This is because armour traits have a function linked to predation meaning so will be more affected by natural selection from predation pressure, compared to other traits such as traits used for feeding. The armour traits which were measured were:

  • First dorsal spine length
  • Second dorsal spine length
  • Length of the longest lateral plate
  • Width of the pelvic girdle
  • Length of the pelvic girdle
  • Length of the pelvic spine
  • Standard length of the fish
  • Number of lateral plates
  • Pelvic scores (Figure 4)

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Figure 3. A stained three-spined stickleback. 1: First dorsal spine length; 2: Second dorsal spine length; 3: Longest lateral plate; 4: Pelvic girdle width; 5: Pelvic girdle length; 6: Pelvic spine length; 7: Standard length.

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Figure 4. Pelvic scores of the stickleback.

The analysis of this data has yet to be done, but will entail creating graphs which are similar to figures 1 and 2 based upon how each trait was measured. Linear models will then be created to allow us to analyse the change in distribution of the traits found in a population. After combining this with known data about predation pressures of each lake, I will be able measure how the strength of selection is affected by different predation pressures.

By Richard Coppins

References

Schluter, D. 2000. The ecology of adaptive radiation. Oxford University Press

MacColl, A. 2011. The ecological causes of evolution. Trends in Ecology and Evolution, 26, 10,514-522

http://evolution.berkeley.edu/evolibrary/article/evo_25

https://www.britannica.com/science/adaptive-radiation