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Sunday, 17 June 2012

Identity

I think like a lot of people I struggle with a sense of identity in its true form. Scratch that I think most if not all of us spend our times pretending to be something else, something we perhaps aren't really.

Don't worry I'm not about to drop some personal bombshell or some such I am just musing.

Honestly!

Although I have been perhaps thinking above and beyond where I am at now. In the present. A lot of my friends are getting married in a short space of time, I am moving house again and I am hankering after the summer holidays so I can relax. On top of this I continue to do my grass is greener looking to the horizon.

Surely though this means I am missing there here and now? Like a person sat on their phone checking facebook or Twitter rather than engaging the people they are with?

Animals seem to have this pegged in their lives, you stop dealing with the there and then and you may not have a future to bother to yourself with.

I'm not suggesting we suddenly go back to survival of the fittest but personally, I will try my best to stop looking ahead too much and trying to push myself into being something else. Instead I will try to concentratw on who and what I am now. Surely that is more important?

Having said that I'd like my parents cats life of sleep, eat and complain!

Maybe next life I can be a house cat...

Saturday, 9 June 2012

something from the pgce days


Raising attainment through enjoyment in Science: A review

Learner attitude towards science seems to change as they progress through the key stages. One theory is that this change is a dip downwards due to the way in which they are taught in key stage 3 and how it differs to what they are used to from key stage 2 (Galton 2002). Galton’s paper talks about how key stage 3 had at the time of writing not changed much over the years and as a result it was a culture shock to the learners as they moved up from their primary schools. He advocated a change in pedagogy rather than changing the curriculum in order to provide more continuity to these learners. The idea being that potential scientists were having bad experiences adjusting in a new school and so being put off the subject group at the beginning of their secondary education. Another slightly different view is that learner opinion of science changes continually throughout their secondary education. This leads to the notion that there is not one hard or fast point at which a learner might be put off science but that the balance is much more finely struck and that the final choice whether to pursue science at post 16 is not made until the learner has to make it (Cleaves, 2005). This scenario seems more realistic considering that science is a core subject that learners are unable to drop until they leave school. It is worth considering that many learners may choose to drop science when they choose their options if they had the choice. Whether this is due to a lack of interest in the subject or because they do not see it as being a subject which is relevant, an issue that apparently exists with history and geography (Adey and Biddulph, 2001), would require further study (although there is a push in science to constantly make links to everyday life). However as there is now a level of choice with regard different paths that a learner can take within school science (triple award, BTEC etc) maybe not having a choice as a reason for a drop in science is no longer a valid point to consider?

It is suggested that one reason why there is a negative attitude towards science is because the idea of challenge (this being defined containing a cognitive or metacognitive component combined with an interest component (Baird et al.1990)) seems to diminish as learners progress through the key stages (Baird and Penna 1997). It is possible that this lack of interesting components as learners approach the ‘business end’ of their school careers begins to move them away from an enjoyment of the subject. This is the notion that the results achieved become more important than the subject being taken. A different idea is that learner’s enjoyment of the subject is not based on their experiences in school but the learner’s background. An extensive study into this by Gorard and See (2009) found that there was a distinct difference between the participation of learners from different economic backgrounds (the lower the economic backgrounds the lower the participation level) however they were unable to come up with a satisfactory explanation for this trend. It was suggested that previous attainment was a factor. That learner’s who did better in key stage 2 were willing to try harder in key stage 3 and so on. This would go against the findings of Galton who claims that it is a more universal drop off, where as the drop being based on previous attainment seems more specific.

The idea that students need challenges is supported by other literature as Covington (2000) wrote a detailed review of goal theory. The idea being that there is a strong link between the will of a learner to work hard and the perceived goals at the end of the task. Whilst this is hardly a groundbreaking finding what was really interesting is that learners seemed to place just as much emphasis on social goals as well as academic goals. A report on learners in P.E. (Carroll and Loumidis, 2001) found that whilst learner enjoyment tended to be similar across the board the attainment level was higher in those learners who invested significant extra time outside of school in the relevant sports, other papers not included here also seem to find similar trends in P.E.. Again however this is not exactly a groundbreaking finding, people who do more sport tend to be better than those who do less, but it does have implications in science. Surely if you could increase the time spent on skills then the learners will get better at what you are doing. In the context of ideas and evidence and how science works there is plenty of scope to perform investigations – which could be dressed up as challenges to the learners – in order so that they all know the difference between continuous and discreet data, that they understand what an independent variable and can present data in an informative way.

The question then becomes two fold. Firstly could improving enjoyment of a subject have a positive effect on results and secondly how can this be achieved? This is especially important as learners attitudes towards science can be based on who their teachers are, the gender of the learner, which curriculum they are following, in short it many different things (Osborne et al. 2003).

Pell (1985) found that those learners who were enjoying their physics lessons also were the ones who performed better. Unfortunately he didn’t say whether he tried different teaching methods to increase the enjoyment or maintain the learner’s interest. It sounds as though he taught the course as he would normally have done and then charted how they enjoyed the lessons and correlated this against their results. Enjoyment of a subject in general is shown to increase the attainment level (Osbourne et al. 2003, Howard- Jones et al. 2002, Gorard and See 2010) This leaves a big question as to whether Pell’s teaching style could have been altered in order to raise the enjoyment and thus the attainment of some of his other learner’s.

One way to increase enjoyment is to use Baird’s definition of challenge in a competition. Competitions in science can easily be implemented and with the increase in coursework based courses they can naturally be added without seeming to be ‘tacked on’ or for the sake of it. Competition is important as it piques interest and because the result is not set learners have been shown to be more receptive and harder working during a competition (Howard-Jones et al. 2002). However it is not practical or beneficial to use competitions every lesson! It is also common for there to be minimal exposition from the class teacher to promote learners to become more proactive with their learning, something which is encouraged and supposed to help raise attainment (Nicol and Macfarlane-Dick 2006). Harris (1990) developed a theoretical model of self regulated learners in order to improve learners behaviour and work ethic however Kirschner et al. (2006) state that minimal instructions are actually to the detriment of a learners ability to perform a task. As such tasks should always be properly scaffolded (Wood, Bruner and Ross, 1976) so that the learner is able to accurately achieve what is being set them, even if the task is meant to be a learner based challenge.

Providing frequent and encouraging feedback also has been shown to be benefit to learners in raising their attainment (Black and William 1998) and this would be especially important with those learners who may be having a difficult time with science because of background, current attainment level or difficulty adapting to a new school. Other ideas to improve enjoyment of science include putting trainee secondary teachers into primary schools to teach some key science skills (Murphy et al 2004). This makes some sense if we consider that it not only improves the teaching of the trainee teachers, but also gives the learners a taste of how secondary teaching might be undertook. Both of these ideas would help to lower the effect of changing school that Galton comments on.  

It is established that enjoyment is linked to attainment. Generally people who enjoy a subject do tend to perform better than those who do not. However what is meant by enjoyment is highly subjective (Lumby 2010). Most pupils seem to agree that in order to increase enjoyment can be increased by variation in lessons, a positive demeanour from the teacher and giving the learners some control over their learning (Gorard and See 2010).

Providing variation, making sure there is some form of challenge and allowing the learners to take ownership of their education are the key things to take away from this review. It appears that efforts to create one ‘catch all’ model are not sufficient. It is the opinion of the author that different groups have different needs and that a teacher should very quickly be able to see what works for a class. In this way lessons can be planned that are both challenging and rewarding for learners, whilst also allowing the learners to enjoy learning about science which should improve their attainment.

Chris Gibson



Words: 1,530










References:

Adey K. and Biddulph M, (2001) The Influence of Pupil Perceptions on Subject Choice at 14+ in Geography and History, Educational Studies, 27(4), 439 - 450 

Baird J.R, R. F. Gunstone, C. Penna, P. J. Fensham and R. T. White (1990), Researching balance between cognition and affect in science teaching and learning. Research in Science Education, 20(1)

Baird J.R.;  Penna C. (1997) Perceptions of challenge in science learning, International Journal of Science Education, 19, 1195 – 1209

Black P and Wiliam D, (1998), Assessment and classroom learning, Assesssment in education: principles, policy and practice, 5(1), 7-74.

B.Carroll  J.ulia Loumidis Childrenís (2001) Perceived Competence and Enjoyment in Physical Education and Physical Activity Outside School European Physical Education Review, 7(1), 24-43

Cleaves A,(2005) The formation of science choices in secondary school, International Journal of Science Education,  27,(4) 471 - 486

Galton M.,(2002) Continuity and Progression in Science Teaching at Key Stages 2 and 3, Cambridge Journal of Education, 32 (2) 249 - 265

Gorard, Stephen and See, Beng Huat (2009) The impact of socio-economic status on participation and attainment in science. Studies in Science Education, 45 (1). pp. 93-129.

Gorard S, and See, B H. (2010) How can we enhance enjoyment of secondary school?:the student view, British Educational Research Journal


Harris K,(1990) Developing Self-Regulated Learners: The Role of Private Speech and Self-Instructions  Educational Psychologist, 25, (1) 35 - 49

Howard-Jones P, Taylor J, & Sutton L. (2002), The effects of play on the creativity of young children, Early Child Development and Care, 172 (4), 323-328.

Kirschner P;  Sweller J ; Clark R (2006) Analysis of the Failure of Constructivist, Discovery, Problem-Based, Experiential, and Inquiry-Based Teaching. Educational Psychologist, 41, (2) 75 - 86

Lumby J, (2010) Enjoyment and learning: policy and secondary school learners' experience in England , British Educational Research Journal 

Martin V. (2001) Covington Goal Theory, Motivation, and School Achievement: An Integrative Review
Annual Review of Psychology, 51, 171-200

Murphy C; Beggs J; Carlisle K; Greenwood J (2004) Students as 'catalysts' in the classroom: the impact of co-teaching between science student teachers and primary classroom teachers on children's enjoyment and learning of science 
International Journal of Science Education, 26, (8) 1023 - 1035

Nicol D and Macfarlane-Dick D, (2006), Formative assessment and self regulated learning a model and seven principles of good feedback practice, Studies in higher education, 31(2), 199-218.

Osborne J.; Simon S;  Collins S (2003) Attitudes towards science: a review of the literature and its implications. International Journal of Science Education, 25 (9) 1049 - 1079

Pell A, (1985) Enjoyment and Attainment in Secondary School Physics British Educational Research Journal, 11, 123 - 132

Wood, D., Bruner, J., & Ross, G. (1976). The role of tutoring in problem solving. Journal of child psychology and psychiatry, 17, 89-100

something from the postgrad days


Entomology Research Project (research so far)

From research so far the main uses of forensic entomology are as follows;

Ø  Determination of time of death.
Ø  Determination of any illicit substances taken by the deceased.
Ø  Sites of injury and any sexual assault.
Ø  Location of death and whether body has been moved.
Ø  Other uses not linked to death include, food tampering, bite marks and hygiene issues. (which I’m not that interested in)

Injury sites
With regard sites of injury and presence of sexual assault, this is mainly due to insect laying habits. Insects tend to lay eggs (occasionally live birth) as close to breaks in the skin as possible. Regular laying sites tend to be around the face as this is likely to be exposed. On the face the corners of the eyes or just under the eye-lids, corners of the mouth, ears and nasal passages are the common places for laying. However in the case of a sexual assault it is noted that the groin area will receive much more insect attention than the face, in fact in some cases it has been noted that the face is neglected in favour of the vagina. The same can be said for wounds on a corpse. Gunshot trauma or other serious injury tends to be common sites for insect laying. This is due to the area being open flesh which is a preferable site as it gives the larvae a relatively easy route into the bulk of the rotting flesh.

The problem however is that investigating this occurrence without using actual cases would be difficult as any experiments running this would pose serious obstacles. It would require the test animal (most likely a pig) to have been wounded before its death or for it to have been violated. Both of which would be difficult achieve and also an ethically a tricky area to circumnavigate. Therefore this area of forensic entomology is not suited to a summer research project, unless the research was to review prior cases and draw conclusions.

Movement of a body
Location of death sites and showing if a body had been moved can be shown by the insects found upon the corpse. Certain species of blow fly only breed in specific areas (the difference between urban and rural species). If a body is killed in an urban area there are chances that flies from that location will lay eggs or have visited the body prior to it being deposited in for instance a rural area where it is left to be visited by the local rural fauna. This can also work for species of insect which are land based and find their way onto a body which is found submersed in water. While this can help narrow down the location that a body originated (and help locate the primary crime scene) it is not specific to certain areas.

There is scope for investigating specific fauna in areas and also showing how long a dead body needs to be left in for example a house on a hot summers day before flies are attracted to it, which could help show how long prior to movement a body had been left. This is an area to think about which could be tested although the it would be fairly specific for the locations used and the climactic conditions present at that time.

Illicit substances present in the deceased

This can be determined firstly by the location and size of the maggots of a similar age to other ones on the same body. This is typically true of ‘super maggots’ found in the nasal cavities of cocaine users. However as maggots feed upon the flesh of the deceased what drugs were in the deceased the present themselves in the maggots, so a toxicology screening of the tissue as well as the stomach contents of the maggots will show which substances are present.

While there is scope for experimentation in this area, feeding pigs cocaine or heroin in order to run the tests post mortem is ethically a very difficult area. This again is an area which is best suited to research based upon actual samples from cases.

Time of death studies

This is possibly they most common use for forensic entomology. Time of death is normally difficult to predict via medical means (liver temperature etc) after 72hours. For these cases the age of insects on the body and the number and species of insects (succession can occur on bodies left for prolonged periods) as well as the temperature and location of the body can all be used to determine the time of death.

This is where there is a lot of scope for research based investigation. Knowing where a body is and which insects it attracts and which insects follow in succession for different areas and climactic conditions could be investigated. As well as the effects of locking a body in a car or house of burying it, then of course it would take insects longer to get to the body. The nature of the internship of the body would also be interesting if it was buried. How well is it buried and what materials are used (coffin against shallow grave). 

Other areas within this to consider are the effects of different events upon the insect communities and how they react to those events. For instance if a body was in a house fire (either to hide the body or the death was due to the fire) will insects artifacts have survived the fire or after the fire will the body still draw insects (for extreme cases where a body has not been discovered following a fire.

In a similar vein if a body is dumped into a body of water what effect will this have on its insect population? If there is any insects before the body is dumped, if not will the body still attract insects, is this dependant on the type of water (pond, river etc) or the depth, (terrestrial species getting to a body part near the surface or aquatic species to a body under the water).

It is these final to areas that I would be interested in researching as I feel that not only would the experiments be feasible but also that the conclusions which could be drawn would have great use in this field. Although it would not be possible to investigate all the areas, the fire angle may be slightly easier to investigate as it would not require finding an area of water which is guaranteed to be undisturbed by passers by. However burying pig bodies in different settings and conditions may be easier to perform than finding a suitable area to ‘mock up’ a house fire.

Further research is still being preformed but this is the stage that my thinking has got too hopefully my ideas are feasable. In terms of details and specific research papers I am still looking (not having access to the forensic science database off campus doesn’t help!).

Chris Gibson


Some of the literature I have read so far;

Chapter 18; the application of entomology to criminal investigations. J. F.Wallman 2004

Chapter 27; on the body: insects’ life stage presence and their postmortem artifacts. N.H. Haskell, R.D. Hall, V.J. Cervenka and M.A. Clark. 1997

Something from the undergrad days


The Resource Availability Hypothesis: A Review



Introduction:

The resource availability hypothesis is a theory that can be applied to both plants and animals. Its use in scientific literature has been diverse with papers having been published treating resource availability like an economic model (Neumayer, 2000) or using an economic analogy in order to explain trends seen in experiments (Bloom et al., 1985). In general terms the hypothesis allows researchers an ecological based tool to describe experimental trends shown by test communities.

This review will concentrate on the hypothesis’ relevancy to plants and plant growth. Firstly however it is important to understand how the hypothesis can be applied to animals in order to provide a broad introduction to the area. Then more specifically the review will look at how the hypothesis fits into plant growth. After this the review will talk about work done within the field with regard resources as nutrients, an area that most research concentrates. It will however also look at the relationship of plants and grazers in the light of the hypothesis, which is another major area within this field.

What is meant by the resource availability hypothesis? :

The flexibility within the hypothesis allows it to be applied to both animals and plants. Experiments on snail dispersal (Byers, 2000) showed that an increased level of resource availability decreased the snail dispersal rate for larger (adult) estuarine snails. Further experiments showed that smaller snails had a higher dispersal rate regardless of the resource levels present. This supported other studies, which had shown less competition amongst the young, small snails. One possible hypothesis for these results was suggest as some form of genetic behaviour present when the snails are young. The behaviour is thought to cause younger snails to disperse more readily in order to avoid competition. Other work carried out which involved manipulating resource levels and its effect on invertebrates was carried out on the Argentine ant Linepithema humile (Aron et al., 2001). By controlling the diets of the ants and providing them with intermediate, high or no extra protein in addition to their diet it was shown that protein increases the number of sexual pupae. Of females more pupae were likely to be queens (rather than workers) and in the entire population the proportion of males was higher. In un-supplemented nests it was shown that protein availability influences the proportion of a brood that is culled. With more sexual pupae culled the lower the amount of protein available to the ants. Other animal studies have been done in vertebrates. One example was work done by Andersson et al. on Arctic char (Salvelinus aplinus) (2005). The study used pond and lake based experiments of differing resources (in this case microinvertebrate and zooplankton amount). The results showed that differences in the levels of zooplankton to microinvertebrate levels caused morphological as well as behavioural differences. The fish that were in a complex environment (high levels of both resources) had a higher dependency upon the zooplankton than their simple environment counterparts. The complex environment fish subsequently were morphologically dissimilar to the simple environment fish as a direct response to this preference.

When looking at the resource availability specifically relating to plants its is important to remember that it is only one of a series of theories which look at the complex relationships between plants and their environments. Some of these theories look at specific aspects of a plants growth and development. For example the carbon-nutrient balance hypothesis (CNBH) is an approach used to understand the patterns of resource allocation within plants. Refining of this theory based upon evidence gathered has allowed it to be a useful guide for ecological research, mainly as it attempts to explain plasticity displayed by individuals without assuming that all responses displayed by individuals are optimal (Lerdau, 2002).

The resource availability hypothesis, however, looks more at effects of resources on both the individual and the population surrounding it. In a lot of literature the resource availability hypothesis is used in descriptions of plant anti herbivore defense. In these studies the resource availability hypothesis states that plants with low relative growth rate and high levels of defense are favored in habitats low in resource availability. Natural selection therefore favors plants with a high maximum growth rate and low defense in habitats of high resource availability. Whereas resource poor-habitats favor plant species with long lived leaves as leaf replacement, and the replacement of lost mineral nutrients is much more costly in poor habitats. So in order to avoid loosing valuable nutrients plants adapted to these environments develop greater levels of anti herbivore defense (Elberse et al. 2003).

This is a common example of a practical application of the resource availability hypothesis. It is used to understand how resource availability impacts upon plant growth and adaptation. By taking this as a general guideline to its use in an experimental context it is clear to see that it is used as a basis for a working experimental hypothesis to test ideas in an empirical and definitive manner.

Studies testing effects of resource availability:

Wilson and Tilman (1991) performed a series of experiments in a 30-year-old field. The experiments concentrated on the effects of fertilization and disturbance on the plant communities. The experiments were conducted on 104 5x5m plots separated by a 2m corridor of untreated vegetation. Tilman had already demonstrated that nitrogen had the greatest limitation on plant growth in that community and so it was chosen to represent fertilization. There were four treatments: no added nitrogen and highest rate of disturbance, highest added nitrogen and no disturbance, no nitrogen and no disturbance and finally highest rate of nitrogen and disturbance. Increasing the levels of nitrogen increased the total community biomass. The species richness within the plots also increased with nitrogen supply, this time however only in undisturbed plots.  In both the undisturbed and disturbed plots vegetation height increased as light penetration decreased. This was coupled with a decreased in root: shoot ratios with the added nitrogen. Leaf allocation decreased with disturbance whereas flowering allocation actually increased despite stem allocation being unaffected by disturbance levels. Similar results were found in yellow nutsedge (Shibuya et al. 2004) where increasing nutrient supply led to increasing plant productivity and associated traits of this, i.e. flowering allocation. Plant productivity could also be seen, as being a form of competition between plants, where increased reproductive success is the outcome of successfully out competing neighboring plants. This has been backed up by competition field studies where manipulation of resources was shown to affect competition intensity (Davis and Pelsor. 2001). Similarly a relationship between fertility and grazing on vegetation grown in infertile soil and on comparatively poor food gave a low ratio of nutrient to fiber and chemical defenses (Bell. 1982). In a different series of experiments Wilson and Tilman were also able to show that above ground competition was greatest in plots with the lowest light penetration (1993). Lower nitrogen availability increased below ground competition and decreased significantly with increasing nitrogen availability. These measurements were recorded in the 3rd year of growing the crop Schzachyrium scoparium, which is a native perennial grass for the area of study. Again disturbance was used, this time tilling annually, which removed all vegetation in each of the 5x5 plots. There were two treatments of nitrogen, non-added or 17gm-2yr-1.

So far the examples have looked at the effect of differences in resource availability within a habitat. Some work has also been done comparing different habitats one study by Brenton and Facelli.(2005) looked at the existence of competition in a temperate rainforest and an area of high stress (a desert). They tested to see if the idea that a plant invests in components, which would greater increase, their chance of maximizing a resource, which is most scarce in that particular habitat, was upheld. Another contrary idea is that plants are in competition in the benign habitat (such as the temperate forest) and as such the ability to gather aboveground resources is kept in check by a positive feedback system. In this hypothesis the intensity of competition is increases as it counts the roots and shoots collectively, this has the effect of increasing the role of resource availability.   The experiments involved a series of glass house experiments as well as observations of tree seedlings in order to assess if there was a logarithmic relationship between competitive intensity and the resource availability. Another aim of the experiments was to show if there was and potential for confounding effects caused by competition and herbivory on a field experiment to determine whether the relationship between experimentally manipulated resource availability and competitive intensity could be manipulated by changing the identity of competing vegetation. The results supported the theory that competitive interactions reach maximum in a fertile environment. This could be because increasing resource availability increases competition between plants (shown earlier) however fertilized plants in outdoor experiments were shown to have a clear link between resource competition and grazing. Those that were grown with a lower nutrient concentration were shown to be grazed more.

These results could be due to the optimal defense hypothesis, which expects there to be a negative relationship between growth and defense. This has been demonstrated in tomato plants (Wilkens et al. 1996). In these tests the effect of resource availability on intraspecific and within-plant allocation of soluble phenolics (rutin and chlorogenic acid) was investigated. By measuring mass as well as physical and cellular attributes of the plants the effects of resource availability on growth was also measured. The experiments showed that plants grown in low resources showed low levels of soluble phenolics and low plant mass. Plants grown in the intermediate solution showed high phenolics but had inhibited growth. Those plants grown at high levels of nutrients however had high growth but no extra phenolic concentrations differences in phenolic concentrations were large enough to have potential consequences for the insect herbivores feeding on the tomato plants. This would have had the knock on effect of increasing the grazing on the lower nutrient grown tomato plants, and possibly be relevant for the tree seedlings previously mentioned.

As with all scientific work though there is some areas related to the hypothesis, which are perfectly feasible in the light of certain evidence but fall short when used in conjunction with other findings. A review article by R.Aerts & F.S.Chapin III (2000) highlighted this when it spoke about the effect of increasing a plants need for nutrient and this impacting upon the plants capacity to absorb the nutrient and that this capacity is specific for that nutrient which most limits a plants growth. To continue using nitrogen (as most examples above have) the need to uptake more will decrease the ability to absorb other nutrients that do not limit the plants growth. At conditions of low nutrient supply the plants ability to uptake will be at its maximum, it will also reduce nutrient leakage at the roots thus allowing them to acquire nutrients at lower external concentrations (Kronzucker et al. 1997). Plants that have a high relative growth rate have the best developed ability to alter their uptake capacity allowing better growth in differing nutrient concentrations, this is consistent with Grime’s (1979) concept that rapidly growing plants have a high capacity to acquire nutrients. However that plants also reduce external concentrations of nutrients to lower levels under conditions of nutrient stress seems to fit with Tilman’s (1988) R* concept of competition. In which the R* is equal to the amount of a nutrient a plant requires to survive in an environment. This is the problem of Tilman and Grime, that they both present ideas in the same areas which after 20 years of research are still not reconciled and have been considered to be detrimental to the understanding how ecosystems function (Craine, 2005). Attempts to bring the two theories together has been attempted the problem is that while they work individually finding a working middle ground between the conflicting theories still proves elusive.


Plants, grazers and the resource availability hypothesis:

Work with grazers not only takes the form of looking at the effect of resource availability and plant growth but also at how available resources can affect the defense strategies of plants. This is an important area, as plants generally have to either invest in growth or defenses against possible grazers. Resource availability is a major determinant of the amount and type of defense present by plant. For example in limited resource areas slow growing plants are favored over fast growing ones as low growth rates favor large investments in antiherbivore defenses. However in areas where rapid growth is favored a positive correlation between predicted and measured growth rates would support the resource availability hypothesis of plant antiherbivore defense (Bryant et al. 1989).

Grazing by herbivores reduces plant fitness. Increasing any form of plant defense either inducible or constitutively expressed is therefore expected to be selected for. Induced responses to herbivory are likened to immune responses in that they can reduce the performance or preference of herbivores. Adaptations made by the plants are assumed to be beneficial to a plant. There is however a lack of experimental evidence demonstrating benefits. There is evidence however showing that following grazing plants increase their levels of chemical, physical and biotic defenses in many species. Some work has been attempted to prove that these defenses increased the fitness by reducing herbivory (Agrawal. 1998). Using wild radish 3 conditions were tested; induced plants, leaf damage controls and overall controls. Using early season flower number as a correlation of male fitness. The leaf damage controls removed the same amount of plant mass but didn’t show the same responses. This it thought to be due to lack of herbivore saliva. Also the area of the leaf that was damaged was reduced. The induced experiment was conducted early in the year then the plants were left to be grazed by natural herbivores. The induced plants showed a greater resistance to herbivory than the control and leaf damage control plants. The protection was not species specific, with all small grazing herbivores affected.

 Leaf lifetime can also be determined by resource availability as it affects the relative advantages of defenses with different turnover rates (Coley et al. 1985). In fact the growth of leaves has been shown to be strongly linked to both resource availability and plant defense strategies. Kurokawa et al. (2004) used dark house experiments to show that a species which traditionally grows in the shade (Eusideroxylon zwageri) has slow growth and in order to prolong lifespan devotes 35% of all production to defensive substances (condensed tannins and lignins). This is an advantageous strategy to survival in dark conditions as these lignins and tannins help to prolog lifespan of its leaves and stems (tannins – leaves and lignins – stems). The growth differentiation balance is another theory, which is different to resource availability. It is used in to explaining the secondary metabolism and structural reinforcement that are physiologically constrained in dividing and enlarging cells thus they divert resources from production of new leaf area (Herms and Mattson, 1992).

 Some plants can display defense plasticity; plastic defenses are when a single genotype can produce different phenotypes depending upon the environment. Plastic responses are favored by selection if plants can respond appropriately to reliable information in their environments. The other side of this is that if a plant is to act on inaccurate information this would actually lower plant fitness as additional resources are being diverted to less essential areas of the plant (Karban et al. 1999).

There is also a transgenerational effect, which is also known as the maternally induced defense. In this non-lethally grazed plants produce defenses against herbivores but will also produce offspring that are better defended when compared to plants produced by non-threatened parents. This is a level of phenotypic plasticity, which works across generations as well as within individuals within the original generation. Endowing offspring with defenses against future grazing which the parent plant has already dealt with will increase the lifetime reproductive success of the second generation. This occurs due to altering of the offspring’s phenotype. Work has been done on wild radishes (Raphanus raphanistrum) Taking wild radishes and exposing them to damage by a specialist caterpillar (Pieris rapae) induced a ten fold increase in indole glucosinolates (mustard oil glycosides) as well as a 30% increase in density of setose trichomes on newly formed leaves of the damaged plants when compared with control’s (Agrawal et al. 1999). In these the tests there control plants and plants that had 50% of each leaf consumed by a caged caterpillar. The experiments where the caterpillar grazing occurred Hydroxylated glucosinolates increased in concentration whereas other classes of glucosinolates decreased. The caterpillars feeding on damaged plants seedlings gained 20% less weight than those, which were fed on the seedlings of undamaged plants. This discrepancy was not explained by seed mass variation of investment in primary metabolites. Seeds from these plants did not differ in nitrogen or carbon content when compared with seeds from undamaged plants and so investment in seedling defenses was concluded to be the reason.  

However Elberse et al. (2003) conducted growth and feeding experiments using aphids and wild barely grown at different nutrient levels. These results found no general nutrient effect on the susceptibility of the barley. However work done before has found both positive (Gruber and Dixon 1988) and negative (Salas et al. 1990) effects of nutrient supply on aphid performance. Most likely these discrepancies are a result of specific chemical defenses of the plants. For example if nutrients were limited it would be expected that there would be an excess of carbon in the plant, this could lead to an accumulation of carbon-based defenses. Compared with a plant grown in resource rich environment, which the expectation would be that its defenses might be based around nitrogen compounds, provided nitrogen was surplus (Bryant et al. 1983).



Conclusion:

Resource availability is a factor in the lives of all living things. It is important to have a workable hypothesis in which constraints upon an organism can be tested. Being able to utilize such a hypothesis as a viable reasoning for observations that have been made but not been fully mechanistically tested is therefore imperative in science. As such the resource availability hypothesis can be applied to various scenarios as a way of explaining certain trends, which have been observed. What it cannot explain is how and as a result of what the trends occur and this is where gaps in knowledge begin to appear.

Most of the work involving resource availability treats it as one possible explanation amidst other theories and explanations. This is probably the best way for the hypothesis to be used as it cannot and could never provide all the answers to questions of plant growth and interaction with the environment. While it is fine to look at specific areas, nutrient availability on growth for example, it would be wrong to solely try and explain trends in plant growth with just one theory. Indeed it must be remembered that plant growth will never be uniform that although trends and similarities between plants can be observed and possibly explained due to the complex nature of the interactions between plant and biotic and abiotic factors of the environment no two plants will ever grow exactly the same. However as a predictive tool and one to help understand the reasons why a plant has displayed the growth it has the resource availability hypothesis is useful and relevant.

Friday, 8 June 2012

Update on snail experiment

Before I begin marking my tests and pretending to be a professional teacher again I thought I would provide an update on where the snail experiments have led me. Albeit slowly (well I am dealing with snails).

Right so what have I found so far.


  1. small snails attempt to get away from the group as quickly as possible - anti predator response.
  2. larger smalls if near each other will crawl all over each other and stay in fairly close proximity to each other
  3. larger snails if away from the group slightly will move away from the others
so what does this mean going forward now? 

  1. research the small snail behaviour only in order to statistically show this is a significant response.
  2. research the larger snail bahaviour only in order to statistically show this is a significant response.
  3. research the above on trial board which has foliage in order to record final snail choices.

There you go, some preliminary research sorted and further research to be getting on with.

However other than the above what else have I learnt?

Well I have learnt that I enjoy the communication of science a lot more than the research side of it. 

Don't get me wrong I love reading up and learning about science but the digesting it and putting it in a more accessible way is something I much prefer to the sitting down and planning a rigorous piece of research.

Although I do enjoy experimenting.

Curious.

Ah well, where are those tests....?

On strange behaviour

I was watching BBC's Planet Earth live (http://www.bbc.co.uk/programmes/p00qj06z) the other day and I came across something pretty special. Not just the Meerkat Ernesto who survived being bit in the face by a Cobra http://www.bbc.co.uk/programmes/p00sqrbf but this clip of humpback whales defending a Grey whale calf http://www.bbc.co.uk/programmes/p00s9h71 .

This is not the only time this has been spotted;

http://www.dnaindia.com/scitech/report_humpback-whales-can-protect-seals-out-of-maternal-instinct_1327958

http://www.guardian.co.uk/world/2009/nov/26/whales-save-seal-from-orcas

http://www2.wdcs.org/blog/index.php?/archives/603-Orcas-versus-humpbacks.html

http://digitaljournal.com/article/324348

I am not going to try to explain this behaviour - I am not sure I have the expertise to do that! But it does make me think about other, strange behaviours which animals sometimes have.

Brings me back to a few mini research ideas I have had over the past year - revisiting my snails and looking at fear.

One of the reasons I love science- so many odd things that crop up.


On the (re)rise of the amateur scientist

So half term eh? One week, two holidays, lots of rain and nearly over.

What do I have left to do? Well year 7 planning for a weeks time has to be sorted and those tests don't mark themselves. The only thing I seem to have gotten through is this month's pay packet.

Ouch.

One thing I have spent of time doing - other than house hunting - is experimenting with my snails.

Or rather I should say observing my snails. For there is a difference and it's taken a bit of this week for me to get used to.

You see I could write up what I have observed on my snails but without lots of data, and statistical analysis of that data what I would have are just things I have seen in a small group of snails that have been potentially exposed to a predator.

Unfortunately that doesn't make for scientific research.

However it is still a worthwhile exercise for me. Why? because I have disproved something I thought I had seen from my undergrad days. Instead I now think I have a better idea of what is happening when the snails are in a group setting.

However I need a lot more data/experimentation before I write it up.

I still will write it up. However for this holiday time has defeated me. For now.

This is what I need to get used to. I am always an all or nothing kind of person however with this situation I think I will have to take baby steps.

So how does this link in with the blog post title?

Well...

One thing that is becoming more common is the use of amateur scientists to support professional science research.

Seti http://setilive.org/, PlanetHunters http://www.planethunters.org/, The Natural History Museum London - bluebell survey (http://www.nhm.ac.uk/resources-rx/files/bluebells-2012-survey-recording-form-61677-61677.pdf)  are 3 I can think of off the top of my head but it does feel that with more and more science becoming commercial the rise of the amateur scientist will become more important.

I know that the BBC already run competitions to allow peoples experiment ideas to be put to the test by professional scientists - 'so you want to be a scientist' http://www.bbc.co.uk/radio4/features/sywtbas/.

As well as the recent Venus transit highlighting that amateur astronomy is still a popular hobby.

Maybe this is where less commercial science will end up? In the public domain again. After all a fair few of the heroes of science were 'gentlemen scientists' who treated science as a hobby alongside being doctors or lawyers etc.

With the world now a smaller place and with the internet giving everyone a voice then maybe we will find more people using that voice to discuss and further science.

Maybe.

It is a big maybe but from personal experience, doing the blog, posting science videos, contributing to discussion groups I know that it is already happening.

Albeit no one has quite written another 'Origin of Species' yet.

Although one of the people using PlanetHunters did find a new planet.

Which I think you will agree is very cool!

So how does this all sum up? Well its simple if you want to do an experiment then have a go. Remember that your not professional so don't spend hours and hours on it, just do a bit every now and then and write up what you find.

Remember your science lessons from school.


  1. have a question in mind and come up with what you don't think will happen - your null hypothesis
  2. only change 1 thing - your independent variable
  3. what your measure is your dependent variable
  4. everything else you should keep the same - controls
  5. try to minimize experimental error - equipment and human
  6. document everything - photo's are good but results tables
  7. avoid drawing early conclusions until you have lots of evidence
  8. take repeats - the more the better - just because you see it once doesn't mean it always happen

Easy, have fun, start small you can build up with experience.

here are a few to start with


  1. do you catch more flies with vinegar or beer?
  2. what cleans a coin better coke or vinegar?
  3. collect rainwater, if you get sediment in the rainwater that is magnetic you have collected iron from space!
  4. do beans grow better with or without soil? 
  5. what effect do different soft drinks have on your heart rate?
Have fun, let me know any results - I am off to set up water traps before it rains again...

Tuesday, 5 June 2012

Beginning of Snail Experiments


When I was an undergraduate my final year research project was on plant nutrition.

I had wanted the project to be on animal behaviour as that was what I was most interested in while studying. However as almost all of the animal behaviour projects had gone to Zoology students the only projects left for those who were on a straight Biology course were ones involving plants.

Luckily for me my dissertation tutor understood that the project I had been assigned was not my first choice. As a result we altered to project to involve some element of animal behaviour specifically looking at the effect of nutrient concentration on wheat desirability to common garden snails. This was given the more impressive sounding title of ‘testing the resource availability hypothesis using winter wheat and garden snails’ when I wrote up my findings for submission. Unfortunately while I found that the snails preferred the wheat grown in the higher nutrient concentration the test plants didn’t show a significant growth difference (difference in dry mass).

One quirk of my research has always stuck with me though. Early on in the project I tried running my preference trials using multiple snails at once for expedience. This was quickly abandoned as the snails would crawl on top of each other and bigger snails would drag smaller ones to one side. This meant that I couldn’t be certain that the snails were making individual choices in which wheat plants they were choosing. The main effect this had on me as a 20 year old student was to increase my experimentation time as I had to test each snail individually.

I spent a lot of the autumn and early winter in an experimental greenhouse watching snails deciding the direction they were going to move in.

Over the intervening years I have always wondered whether the behaviour the snails showed in a group could be replicated. If it could then why the snails did this? Was it a way of making the group of snails too big for a potential predator? Would the smaller snail release the group below it if attacked? Or was it a one off behaviour which has no behavioural benefit?

After many years of never having time to test this I finally made time and decided to observe what happened when I replicated having snails in a group together. A quick peruse around the garden found 5 garden snails – 1 large one, 3 medium sized ones and 1 small snail. As ever the snails were found in small groups under the rims of flower pots.

Annoyingly after a few trials the ‘piggy back’ behaviour I remembered seemed not to be occurring. Instead what seemed to be happening was that the snails just crawled over each other if they were in the way and then moved off.

Slightly perturbed that my interesting snail behaviour seemed to be a one off I decided to look at what was happening when the snails were on top of each other and if this was affected by their size.
I began to notice that the smaller snail when crawling on top of the larger ones didn’t affect the larger snails at all. As a result they carried on moving and dragged the smaller snail away with them. The smaller snail after less than a minute of ‘hitching a ride’ then disembarked off the larger snail and moved away in a different direction.

For the larger snails when they crawled on top of each other the one on top actually stopped the one below from moving. Often the snail on the bottom was starting to get their head out to move. Being crawled on by a larger snail seems to stop them getting ready to move off. This has the effect of delaying them in getting to shelter.

Also whilst the smaller snail seemed to always move away from the larger snails – possibly to avoid predation as it would be less conspicuous than the larger snail. The larger snails followed each other and stuck close together. This could be in order to reduce the chance of them getting predated on. Much like colonial birds living together to remove the chance of their chicks being the ones eaten.

In order to fully describe what is occurring I will further investigate the following;

  1. 1.       Do smaller snails consistently move away from the larger ones if climbing on has occurred?
  2. 2.       Do the similar sized snails consistently follow each other if climbing on has occurred?
  3. 3.       Does climbing on a competitor snail always affect their ability to begin moving to shelter?


It would also be worth cleaning the area between trials so that previous snail tracks are not present so they cannot be affecting the direction the snails are taking.