semans's blog

In this experiment we set out to determine the effects of temperature on the activity level of O. fasciatus and to test whether the insects were most active during an intermediate temperature window of 10-20°C that encompasses the Massachusetts average daytime temperature of 15°C. Our results show that the milkweed bugs start being active at 10°C and that the number of active bugs increases linearly until 20°C, at which point all of the insects show activity.

In both the hot to cold group and the cold to hot group, there is a positive linear correlation between activity count and temperature, with R² = 0.8874 and R² = 0.8893 for each group respectively. These R² values suggest a strong linear correlation between activity and temperature which implies that the number of active insects will increase as temperature increases and vice versa.

However, these data also show that not all of the insects are active in the intermediate temperature zone of 10-20°C. Our data show that there are, on average, 3.79 active insects in this temperature range. Against the null hypothesis that mean activity count will be 10 active insects out of 10 total insects, a T-test yields a p-value of 1.24e-10, which is below 0.05 and therefore statistically significant. Thus, the null hypothesis that O. fasciatus is most active during an intermediate temperature window of 10-20°C is rejected. This analysis evinces that these insects are not at their most active at temperatures that range across the average daytime temperatures in Massachusetts.

Animals have been experimentally shown to navigate their environments using landmarks, beacons, and cognitive maps. A landmark an object or structure distinguishable from the background environment that gives information about the position of and direction to a goal, while a beacon directly locates the goal. A cognitive map is an image of the environment stored in the animal’s memory. The use of landmarks has been demonstrated in animals as different as wasps and birds. In wasps, a test was done where a circle of pinecones was placed around a wasp’s nest, and then moved once the wasp had left. When the wasp returned, it looked for its nest in the pinecone circle, evidencing it use of landmarks. In hummingbirds who were trained to locate a flower based on two differently coloured poles, it was found that moving the poles caused them to look for the flower at its absolute location from the poles. Additionally, Clark’s nutcrackers have been shown to use cognitive maps. In a test where seeds were buried halfway between two landmarks, the nutcrackers managed to consistently locate the seeds even as the landmarks’ absolute distance from each other changed. It was concluded that the nutcrackers had learnt the relationship between the landmarks and the seeds rather than judging distance and position of the seeds based on the landmarks. This has generally been accepted as evidence of a cognitive map in Clark’s nutcracker.

Housing the milkweed bugs

    We placed the milkweed bugs into a 30 x 16 x 21 cm arena at room temperature (~21℃) under a black roof. We gave the bugs shelled sunflower seeds in a dry petri dish as their source of food and water from a cotton stopper on a test tube filled with water as their source of water. We placed the bugs on a 8L:16D day-night cycle and allowed them vision of their surroundings through the plastic walls of the arena. 

Setting up the experiment

    Twelve hours prior to the experimental setup we starved the milkweed bugs by removing the sunflower seeds from their arena. We took a 34 x 29 x 24 cm cardboard box and lined it with a black rubbish bag. We covered the bottom of the box with a layer of ice chunks. We placed a 30 x 16 x 21 cm arena with a blue roof into the box and packed the cleft between the box and the arena with ice. We lined a 30 x 16 x 21 cm arena with a black rubbish bag and clipped a 60W heat lamp onto the top lip of the arena. We roofed the arena with clear plastic clingfilm. We allowed the cold arena to reach 4.6℃ and the hot arena to reach 26.0℃.

Temperature switching and measurements

    We took 20 milkweed bugs from the housing arena and placed 10 of them in the cold arena and 10 of them in the hot arena. We let them habituate for 30 minutes. We simultaneously switched the hot and cold arenas. One lab member removed the rubbish bag wrapping, the clingfilm roof, and unclipped the heat lamp of the hot arena while another removed the cold arena from the ice-packed box and removed its roof. We placed the hot arena into the ice-packed box and put shelled sunflower seeds in a petri dish and a cotton water source in the arena. At the same time, we clipped the heat lamp onto the cold arena, wrapped it with the rubbish bag, and roofed it with clear plastic clingfilm. 

    We recorded temperature and bug activity as defined by movement in both arenas simultaneously: in 15 second intervals for the first 120 seconds, in 30 second intervals until the 720 second mark, and in 60 second intervals until the 1500 second mark. 

    After the experiment had been run we placed the three arenas under the same conditions as the housing arena.

There are multiple ways an animal can find its way around an environment. It is very common for animals to navigate via the use of landmarks and beacons, which they sometimes use to generate cognitive maps. A landmark is defined as an object or structure distinguishable from the background environment that gives information about the position of and direction to a goal. A beacon is defined as an object or structure distinguishable from the background environment that is near a goal and marks its location. A cognitive map is defined as an image of the environment stored in the animal’s memory and is considered present when an animal can generate a novel route to a goal. The use of landmarks has been demonstrated in animals as different as wasps and birds. Concerning wasps, a test was done where a circle of pinecones was placed around the wasp’s nest and once the wasp left, the circle was moved. When the wasp returned, it looked for its nest in the circle of pinecones rather than at the nest’s actual location, which evidenced its use of landmarks. Birds are not only able to use landmarks, as was shown in hummingbirds when poles were used to demarcate flower location and that when the landmarks were moved they followed the landmarks rather than the flower’s actual location, but also the use of cognitive maps. Clark’s nutcrackers have been shown to be able to recognise the relative location of objects, which has been considered evidence of cognitive mapping. In a test where seeds were buried halfway between two landmarks, the nutcrackers managed to consistently locate the seeds even as the landmarks were pushed closer to one another or pulled further apart. In each trial, the birds found the seeds by going to the halfway point between the landmarks rather than looking for the seeds using absolute distance as would be the case if they were solely employing landmarks as indicators of distance.

Game theory is a field of scientific modelling that is most often employed, in simple situations, when the optimal choices of one player depend on the optimal choices of another player. More complex game theory models are described as dynamic and not only take into account the optimal choices of the players but also their respective conditions. A simple game theory model that describes interactions between two players is prisoner’s dilemma. The classic prisoner’s dilemma example involves two prisoners who are under interrogation and have two choices: to cooperate with one another, or to defect and betray on another. This leads to a payoff matrix as follows: 

Thus, in a one-off interaction, the optimal strategy is always to defect, as either you go free or you get a 5 year sentence. Whereas, if you were to cooperate you would either get a 1 year sentence or a 10 year sentence, both of which are worse payoffs than the defecting payoffs. However, over many interactions, cooperation is the best strategy as it has the best average payoff. This model is often used in economics. However, it can also be used in animal behaviour in determining the nature of short-term and long-term group interactions and the development of altruism in a species.

    Ponds contribute more to biodiversity and ecosystem processes than any other small aquatic ecosystems. Preliminary research has shown that they house the most species, the most unique species, and the most rare species of all small aquatic ecosystem types. This information has only been identified recently, so there is a need for research into pond biodiversity and possible dangers to this ecosystem’s integrity. Scientists have suggested from early research that these small aquatic ecosystems are highly valuable in terms of biodiversity and ecosystem use. Without further research into these ecosystems, we pose a risk of losing oases of species diversity whose full value has yet to be understood. This loss could prove a crippling blow to species diversity on a global scale. With this in mind, we aim to determine the health of local pond ecosystems that have yet to be studied in order to prevent such catastrophic loss.

There are several reproduction repression mechanisms in eusocial and social species. Honey bees are a eusocial species that have a reproductive division of labour with only one reproducing queen. Worker bee reproduction is limited by the level of royal jelly provisioning. If the larvae doesn’t receive enough royal jelly then then it will not develop ovaries and will not be able to lay eggs, only potential founder queens are given enough royal jelly to produce ovaries and hence eggs. Naked mole rats are the only eusocial mammals and also have a queen that mediates reproduction repression in her subordinates. Should any of the subordinate females reach reproductive maturity and show signs of reproductive intent, the queen will bully the females by biting and scratching them. This causes stress hormones to be produced in the bullied female which will in turn repress the production of stress hormones and limit reproduction. Though not truly eusocial, meerkats are group living animals that suppress reproduction in a similar fashion to naked mole rats. During the breeding season, if dominant females fear reproductive competition from subordinate females they will temporarily evict those females from the group. Evicted females will produce more stress hormones than females that remain in the group which will, in turn, suppress production of their reproductive hormones. This is additionally evidenced by the fact that evicted females have higher rates of abortion and lower rates of conception than females who remain in the group.

Though modern methods for introducing transgenes into an organism are diverse, there are two historically important procedures that were the progenitors of transgenic organisms. Palmiter and Brinster were the first to introduce foreign genetic material to an organism. They added the gene for human growth hormone (HGH) to a mouse zygote at the point where the haploid genomes are fusing to cause random incorporation of the transgene into the host genome. In addition to the transgene payload, Palmiter and Brinster added a promoter in front of the transgene in order to get expression in the transformed mice. Following this historical achievement came the knock-in engineering in embryonic stem (ES) cells developed by Capecchi, Martin, and Smithies. This method involved in vitro transformation of ES cells as opposed to direct zygotic injection. They removed the promoter from the transgene, added arms of homology and a neomycin resistance gene. The promoter is unnecessary as the arms of homology will target the transgene to an already active promoter in a pre-existing gene. The transgenes are then added to electroporated ES cells in order to allow the transgene payload to enter the ES cells. The cells that take up the transgene and undergo a double-stranded (DS) break that matches the transgene’s arms of homology get transformed. Then, the antibiotic neomycin is added to the cultured cells to select for the cells that were transformed. These transformed cells are injected into a mouse blastocyst in order to express the transgene in the adult organism.

Bees are a haplodiploid species. Thus, males come from unfertilised eggs and are haploid while females come from fertilised eggs and are diploid. All of the bees in a colony are sisters and males are only produced in order for the queen bee to mate or to found a new colony. Additionally, the queen tends to be monogamous such that all of her daughters always share 50% of their genetic material with one another. Since the daughters are diploids, half of their genetic material comes from their mother, which on average yields 25% relatedness between sisters. This means that, on average, daughters of a monogamous queen will be 75% related to one another. This relates to indirect fitness, which is a measure of an individual’s fitness based on the number of offspring a relative gains through that individual’s help. It is hypothesized that eusociality has evolved in bees because of this increased relatedness between sisters, as it would generate an increased gain in indirect fitness as compared to sisters that are only 50% related as would be the case if the queen were not monogamous. However, due to the fact that there is a greater fitness gain if daughter biased colonies start producing more males than females, a benefit that outweighs any indirect fitness gain that females acquire by helping make more females, this hypothesis is insufficient to explain eusociality in bees.

Small aquatic ecosystems are critical contributors to freshwater biodiversity and freshwater ecosystem services. Ponds in particular house more rare and unique species than any other small freshwater ecosystem. However, little research has been done into measuring the ecosystem integrity of small aquatic ecosystems due to few evaluations in the effects of anthropogenic activities on these ecosystems. In this proposal, we aim to evaluate the ecosystem integrity of small aquatic ecosystems local to the Amherst, Massachusetts area by (1) determining their flora biodiversity, (2) measuring their quality of the matter economy, and (3) identifying sustainable architecture structures around them. We will use Simpson’s biodiversity index as a simple measure of plant biodiversity, use soil core samples as a timeline of the matter economy, and we will compare the number of current sustainable architecture structures with previous numbers. With this data, we will determine if the priority of green architecture in local construction developments have followed the same upward trend observed on a national scale. Without research into these ecosystems, we risk losing valuable oases of biodiversity and the opportunities to identify anthropogenic factors that may threaten ecosystems on a global scale.