Biology – Emma J. McKeon: Aspiring Animal Behaviorist https://emckeon.agnesscott.org Mon, 02 Dec 2019 17:31:00 +0000 en hourly 1 https://wordpress.org/?v=5.3.2 https://emckeon.agnesscott.org/wp-content/uploads/2017/02/cropped-Traces-Icon-Paws-Reprint-Cat-Silhouette-Animal-1345885-32x32.png Biology – Emma J. McKeon: Aspiring Animal Behaviorist https://emckeon.agnesscott.org 32 32 Northern Mockingbirds (Mimus polyglottos) and Brown Thrashers (Toxostoma rufum) Preferentially Nest in Areas with Low Levels of Artificial Light at Night https://emckeon.agnesscott.org/stem/northern-mockingbirds-mimus-polyglottos-and-brown-thrashers-toxostoma-rufum-preferentially-nest-in-areas-with-low-levels-of-artificial-light-at-night/ https://emckeon.agnesscott.org/stem/northern-mockingbirds-mimus-polyglottos-and-brown-thrashers-toxostoma-rufum-preferentially-nest-in-areas-with-low-levels-of-artificial-light-at-night/#respond Thu, 14 Nov 2019 22:47:27 +0000 http://emckeon.agnesscott.org/?p=436 Research conducted as part of a Behavioral Ecology course in Spring 2019

Abstract

Because of the increase in urban human populations and the decrease in forest areas, it is crucial that scientists focus efforts on investigating the influence of artificial light at night (ALAN) on urban wild animal populations. While behavioral and physiological changes in avian species in response to light pollution have been studied in the past, so far there has not been a study investigating ALAN-mediated nest site selection in our focal species. Here, we tested whether ALAN influenced where Northern mockingbirds (Mimus polyglottos) and brown thrashers (Toxostoma rufum) preferred to nest. This relationship was investigated by creating an illumination map of a college campus in Decatur, GA (33.7692° N, 84.2946° W) and testing the illumination levels at currently active and previously active nest sites, as well as the illumination at randomly selected control sites, areas where it was possible to build a nest but no nest was found. We found that these species do in fact preferentially nest in areas with low ALAN, suggesting that they may use this as a strategy to avoid the negative fitness and wellness effects of night time illumination.

            Keywords: urban ecology, avian nest selection, light pollution, ALAN

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Cooperation in the Family Corvidae https://emckeon.agnesscott.org/psych/cooperation-in-the-family-corvidae/ https://emckeon.agnesscott.org/psych/cooperation-in-the-family-corvidae/#respond Thu, 14 Nov 2019 22:40:01 +0000 http://emckeon.agnesscott.org/?p=434 Written in Spring 2019

Abstract

The purpose of this review was to investigate the literature on cooperation in members of the family Corvidae, to examine where they excel and where they fall short. Cooperative behavior has been used in the past to investigate cognitive abilities, namely the ability to recognize kin, remembering who they’ve cooperated with in the past, reciprocity, tracking the reputation of others, understanding equity, and low temporal discounting. These abilities were discussed in the context of the literature mentioned in order to tie the research directly to the cognitive abilities of corvids. It was found that while members of this family excel at cooperating in different environments, they tend to have low inhibition control and do not attend to long-term consequences of defection. However, this lack of inhibition control may not suggest cognitive deficits, but simply the impulsive nature of animals in this family.           

  Keywords: Corvidae, cooperation, animal cognition, social behavior

Cooperation in the Family Corvidae

            Cooperation is a widely discussed and rigorously studied topic within the fields of animal behavior and behavioral ecology and was defined briefly by Stephens and Hauser (2004) as joint action for mutual benefit. However, authentic cooperation is difficult for scientists to pin down, as it is difficult to tell when animals truly understand the need to cooperate, as opposed to simply learning they need to complete a task with a conspecific. Because of this, reviews and studies have looked into the requirements for cooperation, particularly cognitive requirements, and have found a few common themes; for animals to cooperate, they need to possess the ability to remember who they’ve cooperated with in the past, engage in reciprocity, track the reputation of others, understand equity, and have low temporal discounting (Bear, Kagan, & Rand, 2017; Esteban, 2013; Stephens & Hauser, 2004). Because of these rigorous cognitive requirements, studying cooperation has often been used to understand the cognitive abilities of animal species, and cooperative behaviors have been shown in some of the most popular “smart” species such as elephants and dolphins (Kuczaj et. al, 2015; Plotkin et. al, 2011).

            There is another group of animals that have recently come into the spotlight on the cognitive stage; the Corvidae family. This group includes crows, jays, ravens, magpies, rooks, and more, and has been studied extensively in recent years to analyze their cognitive abilities, with shocking results. Most studies have found that members of this family are incredible problem solvers with a powerful memory and the ability to make and use tools (Clatyon et. al, 2007; Gould-Beierle, 2000; Hofmann et. al, 2016; St Clair et. al, 2016). However, cooperation across the entire family to assess cognitive abilities has yet to be examined. This review seeks to fill that gap in the literature and use cooperation to assess the cognitive abilities of members of the family Corvidae.

“Crows” by lefthandgergo is licensed under CC BY-NC-SA 2.0 

CORVIDAE SOCIAL STRUCTURE

            Corvids are known to exist in flocks and have very complex social structures. For instance, Braun et. al (2012) found that common ravens (Corvus corax) maintain strong social bonds both in captivity and in the wild, and that in the wild, subgroups of two to five individuals are shown to exhibit allo-preening and combined play behaviors. Another study investigated the social intelligence hypothesis in various bird species and found that corvids ranked high in their sociality, and even compared their social complexity to that of primates (Emery et. al, 2007). Because corvids live in these highly complex social environments with related and non-related individuals, it seems likely that cooperation would occur. Thus, the next topic of discussion is naturally when and how corvids cooperate, and when and how they fail to do so.

SUPPORT FOR COOPERATION

Cooperation in the lab

Cooperation tasks, such as the rope-pull task (Plotkin et. al, 2011), and game theory models of cooperation, such as the prisoner’s dilemma (Clements & Stephens, 1995), are commonly used to observe and assess cooperative behavior in a laboratory setting. Many studies have been done using these assays in corvids. For instance, Clements and Stephens (1995) found that when modeling a mutualism environment, wherein mutual cooperation pays best, blue jays (Cyanocitta cristata) readily cooperated with a partner for a food reward. The results of this study displayed that in a highly applicable model of cooperation, the jays were able to understand that in terms of immediate benefit, cooperation would offer the most rewards.

However, corvids are shown in other studies to go above and beyond simple reward assessments. A study done by Wascher and Bugnyar (2013) found that in two species of corvids (common ravens and carrion crows (Corvus corone)), individuals will not cooperate in situations when they are not receiving equal rewards, or when they recognize that their partner is receiving the same reward but not putting forth as much effort. While this study displays a lack of cooperation, it shows that ravens and crows can understand how much their partner is working, as well as the equity of the rewards they are receiving. This sensitivity to inequity is one of the cognitive requirements of cognition mentioned before, as well as the ability to track the reputation of others (which includes understanding how hard they work).

Lastly, Fraser and Bugnyar (2012) conducted a study looking at reciprocity and agonistic support (defined as a third party intervening in an ongoing conflict to attack one of the conflict participants, thus supporting the other) in common ravens. The researchers found that ravens will engage in long-term reciprocation of agonistic support and were more likely to support relatives and those who preened them. Interestingly, the ravens were not shown to engage in short-term reciprocation, which goes against the common trend in the literature that corvids attend to short-term rewards and reciprocity. The results of this study suggest that ravens check many of the cognitive requirement boxes, including the ability to remember who they’ve cooperated with in the past, the ability to engage in reciprocity, the ability to track the reputation of others, the ability to understand equity, and the ability to limit temporal discounting.

Cooperation in the wild

            While studies conducted in the lab are beneficial because of the high amounts of control a researcher can have over confounding variables, this unnatural environment can also lead to inaccurate understandings of an animal’s true abilities. Thus, it is incredibly beneficial for scientists to also look at behavior in the wild, especially when analyzing cooperation.

            One common cooperative behavior seen in a lot of corvid species is cooperative breeding, wherein individuals will band together to take care of the young of the group, whether they are directly related or not. Baglione et. al (2003) found this behavior in carrion crows, namely in that non-reproducing offspring and immigrant males aid breeding pairs in raising their young. Bosque and Molina (2002) found that cayenne jays (Cyanocorax cayanus) exhibit not only cooperative breeding, but also cooperative nest defending behaviors. Cooperative breeding is a simple yet incredibly common behavior, especially in New World corvids, which contain the most common corvid species such as jays, rooks, ravens, and crows. This behavior allows us to look at kin selection, one of the simplest bases of cooperation, which postulates that individuals care for those related to them in order to increase their direct and indirect fitness. While kin selection may be very basic, it does require various cognitive abilities, including the ability to recognize your kin.

            Outside of kin selection, wild corvid species have also displayed other cooperative behaviors. One study, conducted by Fraser and Bugnyar (2011), found that ravens will reconcile after fights with valuable partners, namely those who the individual will interact with in the future and who they share a valuable relationship with. Before this study, reconciliation had not been shown in avian species, but once again, corvids prove their abilities to understand their relationships with others outside of pair bonds, and how these relationships can help them in the future.

“Deva” by Frantisek_Trampota is licensed under CC PDM 1.0 

LIMITATIONS OF COOPERATION

            While corvids clearly display several cooperative behaviors that require vast cognitive abilities, some studies show that they often can fall short when it comes to working with others. There is one main shortcoming shown by the research: a lack of patience.

Lack of patience

            As mentioned before, except for a few studies like Fraser and Bugnyar’s (2012), which looked at reciprocity and agonistic support, most of the literature shows a lack of attention to long-term consequences and rewards in the corvid family. For instance, Clements and Stephens (1995) showed that while jays choose to cooperate in a mutualism environment, they do not choose to cooperate when placed in a prisoner’s dilemma environment, wherein the benefits of mutual cooperation are not much better than the benefits of mutual defection. This suggests that they attended more to the short-term rewards than the long-term consequences of defecting, and thus struggle with high temporal discounting. Other studies have shown this lack of cooperation in the absence of immediate benefit (Seed et. al, 2008; Stevens & Stephens, 2004).

Impulsive nature

            However, this lack of attentiveness to long-term consequences could be more related to impulsivity in the Corvidae family than to shortcomings in cognitive abilities. Previous research on corvids’ abilities to delay gratification shows that they struggle with this concept. For instance, Wascher et. al (2012) showed that crows are impulsive in their choice of rewards, even when they know a larger reward will come to them if they wait. So, for corvids to suddenly abandon their impulsive nature in order to cooperate would be abnormal, suggesting that this impulsivity is simply a barrier to cooperation that members of the family must overcome, regardless of their cognitive abilities.

CONCLUSION

            All in all, past research has shown that corvids possess many of the cognitive requirements for cooperation, including conspecific recognition, reciprocity, and an understanding of equity (Baglione et. al, 2003; Bosque & Molina, 2002; Clements & Stephens, 1995; Fraser & Bugnyar, 2012; Fraser & Bugnyar, 2011; Wascher & Bugnyar, 2013), and these findings exist both in lab settings and in the wild. However, they also showed a lack of inhibition control and high levels of temporal discounting in many corvid species (Clements & Stephens, 1995; Seed et. al, 2008; Stevens & Stephens, 2004). Despite these shortcomings, corvids show incredible levels of cooperation, suggesting high cognitive abilities, which falls in line with previous research done on their cognitive abilities outside of cooperation (Clatyon et. al, 2007; Gould-Beierle, 2000; Hofmann et. al, 2016; St Clair et. al, 2016). This review suggests many possible avenues of research, including looking into other examples of cooperation in corvids to expand the wealth of literature, or comparing the cognitive abilities of corvids and other non-human animals (or even humans themselves).

References

Baglione, V., Canestrari, D., Marcos, J.M., & Ekman, J. (2003). Kin selection in cooperative alliances of carrion crows. Science, 300(5627), 1947-1949. doi: 10.1126/science.1082429

Bear, A., Kagan, A., & Rand, D. G. (2017). Co-evolution of cooperation and cognition: the impact of imperfect deliberation and context-sensitive intuition. Proceedings. Biological Sciences, 284(1851). https://doi.org/10.1098/rspb.2016.2326

Bosque, C., & Molina, C. (2002). Communal breeding and nest defense behavior of the cayenne jay (Cyanocorax cayanus). Journal of Field Ornithology, 73(4), 360-362. http://dx.doi.org/10.1648/0273-8570-73.4.360

Braun, A., Walsdorff, T., Fraser, O., & Bugnyar, T. (2012). Socialized sub-groups in a temporary stable raven flock? Journal of Ornithology, 153, 97–104. http://dx.doi.org/10.1007/s10336-011-0810-2

Clayton, N.S., & Emery, N.J. (2007). Social cognition by food-caching corvids. The western scrub-jay as a natural psychologist. Philosophical Transactions of the Royal Society B: Biological Sciences362(1480), 507–522. http://dx.doi.org/10.1098/rstb.2006.1992

Clements, K.C., & Stephens, D.W. (1995). Testing models of non-kin cooperation: mutualism and the prisoner’s dilemma. Animal Behavior, 50, 527-535. http://dx.doi.org/10.1006/anbe.1995.0267

Emery, N. J., Seed, A. M., von Bayern, A. M. P., & Clayton, N. S. (2007). Cognitive adaptations of social bonding in birds. Philosophical Transactions of the Royal Society B: Biological Sciences, 362, 489-505. https://doi.org/10.1098/rstb.2006.1991

Fraser, O.N., & Bugnyar, T. (2012). Reciprocity of agonistic support in ravens. Animal Behaviour, 83, 171–177. https://doi.org/10.1016/j.anbehav.2011.10.023

Fraser, O. N., & Bugnyar, T. (2011). Ravens reconcile after aggressive conflicts with valuable partners. PLoS ONE, 6(3), 1-9. http://dx.doi.org/10.1371/journal.pone.0018118

Freidin, E. (2013). A critical review of the hypothesis that cognitive requirements constraint animal reciprocity. Revista Argentina de Ciencias Del Comportamiento, 74(2). Retrieved from https://search.ebscohost.com/login.aspx?direct=true&AuthType=ip,shib&db=edsdoj&AN=edsdoj.7ee1526acf1b47c98df6e309cb393fc9&site=eds-live&scope=site

Gould-Beierle, K. (2000). A comparison of four corvid species in a working and reference memory task using a radial maze. Journal of Comparative Psychology, 114(4), 347–356. https://doi.org/10.1037/0735-7036.114.4.347

Hofmann, M.M., Cheke, L.G., & Clayton, N.S. (2016). Western scrub-jays (Aphelocoma californica) solve multiple-string problems by the spatial relation of string and reward. Animal Cognition, 19(6), 1103–1114. Retrieved from https://search.ebscohost.com/login.aspx?direct=true&AuthType=ip,shib&db=mnh&AN=27470204&site=eds-live&scope=site

Kuczaj, S.A., II, Winship, K.A., & Eskelinen, H.C. (2015). Can bottlenose dolphins (Tursiops truncatus) cooperate when solving a novel task? Animal Cognition, 18(2), 543–550. https://doi.org/10.1007/s10071-014-0822-4

Plotkin, J.M., Lair, R., Suphachoksahakun, W., & de Waal, F.B.M. (2011). Elephants know when they need a helping trunk in a cooperative task. PNAS, 108(12), 5116-5121. https://doi.org/10.1073/pnas.1101765108

Seed, A. M., Clayton, N. S., & Emery, N. J. (2008). Cooperative problem solving in rooks (Corvus frugilegus). Proceedings: Biological Sciences, 275(1641), 1421-1429. http://dx.doi.org/10.1098/rspb.2008.0111

Stephens, J.R., & Hauser, M.D. (2004). Why be nice? Psychological constraints on the evolution of cooperation. Trends in Cognitive Sciences, 8(2), 60-65. doi:10.1016/j.tics.2003.12.003

St Clair, J.J.H., Klump, B.C., Wal, J.E.M., Sugasawa, S., & Rutz, C. (2016). Strong between-site variation in New Caledonian crows’ use of hook-tool-making materials. Biological Journal of the Linnean Society, 118(2), 226–232. https://doi.org/10.1111/bij.12757

Stevens, J. R., & Stephens, D. W. (2004). The economic basis of cooperation: tradeoffs between selfishness and generosity. Behavioral Ecology, 15(2), 255-261. https://doi.org/10.1093/beheco/arh006

Wascher, C. A. F., & Bugnyar, T. (2013). Behavioral responses to inequity in reward distribution and working effort in crows and ravens. PLoS ONE, 8(2), 1–9. http://dx.doi.org/10.1371/journal.pone.0056885

Wascher, C.A.F., Dufour, V., & Bugnyar, T. (2012). Carrion crows cannot overcome a delay of gratification in a quantitative exchange task. Frontiers in Comparative Psychology, 3(118), 1-6. https://doi.org/10.3389/fpsyg.2012.00118

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Male Bean Beetles (Callosobruchus maculatus) Show a Preference for Virgin Females https://emckeon.agnesscott.org/stem/male-bean-beetles-callosobruchus-maculatus-show-a-preference-for-virgin-females/ https://emckeon.agnesscott.org/stem/male-bean-beetles-callosobruchus-maculatus-show-a-preference-for-virgin-females/#respond Thu, 14 Nov 2019 22:31:02 +0000 http://emckeon.agnesscott.org/?p=432 Research conducted for a Behavioral Ecology course in Spring 2019

Male Bean Beetles (Callosobruchus maculatus) Show a Preference for Virgin Females

McKeon, E. J., Dyer, Z., Umana, J., and Levin, I. I.

Agnes Scott College

Abstract

The male bias for choosing virgin mates has been shown in many different invertebrate species, and has many consequences for male fitness. The current study sought to explore male mate choice in Callosobruchus macalatus and to provide more evidence for the virgin mate bias. We hypothesized that male bean beetles prefer virgin mates, and we predicted that if we presented virgin male simultaneously with the choice between a virgin and a non-virgin female to mate with, the male would chose the virgin female. Our results supported a significant bias for virgin females in open field mate trials, X2(1, N = 20) = 19.80, p < 0.0001, and showed an 8:1 bias for virgin:mated females. These findings also provide many options for future research in the field.

Discussion

Our hypothesis that male bean beetles prefer virgin mates was highly supported (p < .0001), and we found that there was no influence of female size on male choice latency (p = .607). Another group of researchers in our lab investigating the effects of female and male size on mate choice and copulation success found no significant effects of female size on male choice. Therefore, we can reasonably assume that mate choice in bean beetles is at least strongly influenced by female mating status, and is in line with previous studies investigating this bias in other animal species (Baruffaldi & Costa, 2014; Burris & Dam, 2015; McNamara, Jones, & Elgar, 2004).

Our study did have a few weaknesses, including our small sample size (N=20) and the lack of knowledge about the actual mechanism(s) males use to identify female mating status, although McNamara, Jones, and Elgar (2004) suggest olfaction plays a key role in this process in a similar species, the Hide Beetle (Dermestes maculatus). However, the latter weakness is in itself a strength in that it identifies a possible avenue of research in the area of male mate choice. 

Our findings also support the idea that male mate choice is a crucial aspect in increasing paternity and lowering sperm competition in polygamous species, as seen in other past studies (Archer & Elgar, 1999; Gromko & Pyle, 1978). This bias for virgin females makes sense in this context, as males who mate with virgin females are not faced with automatic sperm competition as males who mate with virgin females do. Virgin females are also often younger, which possibly could be related to an increase in fecundity. Conversely, if a male encounters an older virgin, she likely either has valuable characteristics that have allowed her to maintain this virginity into her old age, or she might live in an area with a low concentration of competing males, which could also decrease the chances of sperm competition. Either way, having a bias for virgin females is a effective, and evidently common, method males can use to assure paternity and direct fitness. Further research could be done to see if this bias exists in other species, such as avians or mammals.

References

Šešlija, D., Marečko, I., & Tucić, N. (2008). Sexual selection and senescence: do seed beetle males ( Acanthoscelides obtectus, Bruchidae, Coleoptera) shape the longevity of their mates? Journal of Zoological Systematics & Evolutionary Research, 46(4), 323–330. https://doi.org/10.1111/j.1439-0469.2008.00469.x

Baruffaldi, L., & Costa, F. G. (2014). Male reproductive decision is constrained by sex pheromones produced by females. Behaviour, 151(4), 465–477. https://doi.org/10.1163/1568539X-00003136

Gromko, M. H., & Pyle, D. W., (1978). Sperm Competition, Male Fitness, and Repeated Mating by Female Drosophila melanogaster. Evolution, 32(3), 588. https://doi.org/10.2307/2407724

Martinossi‐Allibert, I., Savković, U., Đorđević, M., Arnqvist, G., Stojković, B., & Berger, D. (2018). The consequences of sexual selection in well‐adapted and maladapted populations of bean beetles. Evolution, 72(3), 518-530. https://doi.org/10.1111/evo.13412

Sakurai, G., & Kasuya, E. (2008). Different female mating rates in different populations do not reflect the benefits the females gain from polyandry in the adzuki bean beetle. Journal of Ethology, 26(1), 93. https://doi.org/10.1007/s10164-007-0036-1

Johnstone, R. A., Reynolds, J. D., & Deutsch, J. C. (1995). Mutual mate choice and sex differences in choosiness. Evolution, 50(4), 1382-1391. https://doi.org/10.1111/j.1558-5646.1996.tb03912.x

Archer, M. S., & Elgar, M. A. (1999). Female preference for multiple partners: sperm competition in the hide beetle, Dermestes maculatus (DeGeer). Animal Behavior, 58(3), 669-675. https://doi.org/10.1006/anbe.1999.1172

Bonduriansky, R. (2001). The evolution of male mate choice in insects: a synthesis of ideas and evidence. Biological Reviews, 76(3), 305-339. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/11569787

Burris, Z. P., & Dam, H. G. (2015). Female mating status affects mating and male mate-choice in the copepod genus Acartia. Journal of Plankton Research, 37(1), 183–196. https://doi.org/10.1093/plankt/fbu090

Crudington, H. S., & Siva-Jothy, M. T. (2000). Genital damage, kicking and early death. Nature, 407, 855–856. https://doi.org/10.1038/35038154

Johnstone, R. A., Reynolds, J. D. and Deutsch, J. C. (1996). Mutual Mate Choice And Sex Differences In Choosiness. Evolution, 50, 1382-1391. https://doi.org/10.1111/j.1558-5646.1996.tb03912.x

McNamara, K. B., Jones, T. M., & Elgar, M. A. (2004). Female Reproductive Status and Mate Choice in the Hide Beetle, Dermestes maculatus. Journal of Insect Behavior, 17(3), 337–352. https://doi.org/10.1023/B:JOIR.0000031535.00373.b1

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Movement of C. elegans in response to environmental levels of nitrogen https://emckeon.agnesscott.org/biology/movement-of-c-elegans-in-response-to-environmental-levels-of-nitrogen/ https://emckeon.agnesscott.org/biology/movement-of-c-elegans-in-response-to-environmental-levels-of-nitrogen/#respond Wed, 02 May 2018 18:27:31 +0000 http://emckeon.agnesscott.org/?p=279 Written in Spring 2018

Introduction

Caenorhabditis elegans are considered a model organism because of their fast reproduction rate, short development period, and transparency, all factors that make them easy to study in the lab. Thus, much research that pertains to humans and animals is first done on C. elegans. What interested our group in particular was the chemosensation of C. elegans, and their behavior in response to various chemicals in their environment.

We were offered the chance to use Rhizobium leguminosarum, a nitrogen fixing bacteria, in our study, so we decided to study the reaction of C. elegans to nitrogen in their environment. Because nitrogen is a waste product produced by C. elegans (Eisenmann 2005), we hypothesized that as higher concentrations of nitrogen were introduced to an enclosed space, C. elegans would exhibit a behavioral response. Our specific prediction was that the C. elegans would move away from the nitrogen source.

Discussion

While our results were not significant, and thus our hypothesis was rejected, we did see an interesting trend in our data. In the first experimental group, there was a more visibly pronounced movement away from the R. leguminosarum than in the control or second experimental groups. This could indicate that only certain levels of nitrogen repel C. elegans, which could be an evolutionary adaptation to prevent them from avoiding areas that are nitrogen-rich but that do not necessarily contain waste materials. However, this is just a speculation and further research would be needed to verify this claim.

Some limitations in our study included lack of measurements for some time slots, a small number of plates used, and the fact that we chose 10μL and 100μL as our R. leguminosarum measurements randomly, and different levels of the bacteria may have had a significant effect. Future research should take these limitations into account, and could investigate C. elegans behavior around other waste particles. Research in this area could assist with conservation and health initiatives, as it could reveal the behavior of animals around waste products. It could also shed light on issues caused by pollution and inadequate spacing in and cleaning of enclosures for animals in captivity.

References

Eisenmann, D. M., Wnt signaling (June 25, 2005), WormBook, ed. The C. elegans Research

Community, WormBook, doi/10.1895/wormbook.1.7.1, http://www.wormbook.org.

Tsunekage, T.  (2018). Lab 3 – Introduction to Caenorhabditis elegans. Retrieved March 19,

2018.

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Systems of Dictyostelium; A Wiki-entry https://emckeon.agnesscott.org/biology/systems-of-dictyostelium-a-wiki-entry/ https://emckeon.agnesscott.org/biology/systems-of-dictyostelium-a-wiki-entry/#respond Mon, 27 Nov 2017 22:14:16 +0000 http://emckeon.agnesscott.org/?p=263 From a systems biology standpoint, Dictyostelium is a fascinating genus. Systems biology refers to the interdisciplinary area of biology that uses a holistic computational and mathematical models to describe biological systems. These can be the systems within an organism, as well as interactions between organisms as a system. It also discusses emergent properties, tissue and organ properties and organisms functioning as a theoretical system.

The genus Dictyostelium exists in the order Dictyosteliida, also known as social amoebae.  For many years Dictyostelium, specifically D. discoideum, has been a favorite subject of systems biologists because of its uni- and multicellularity. When members of the Dictyostelium genus begin life, they are a single celled haploid, and have a very standard eukaryotic anatomy. They will usually remain in this vegetative state as long as bacteria living in the soil, their main food source, remains plentiful enough and they will divide by mitosis periodically. However, once food becomes scarce, members of this genus will enter a starvation state, which forces them to transform into their multicellular state. The cells will become able to aggregate, forming a mound, a first finger, then they become multicellular slugs, which migrate from their low-light environment to find light. Once they find enough light, they transform into culminates which become a fruiting body with a long stem and a mass of spore cells on top, ready to be distributed. It is this very process, wherein a unicellular organism is able to aggregate and become a multicellular organism for reproduction, that is so fascinating in the realm of systems of biology. This is because there are now multiple levels to the system. It is no longer single cells and their anatomical systems as well as cells interacting and competing for resources, but there are now systems of cells forming various multicellular organisms, and these multicellular organisms competing to get the best resources and spread their spores efficiently.

What’s even more fascinating is that members of the genus Dictyostelium are able to adapt to their environments in the multicellular state by altering their unicellular counterparts. In a study by Bonner and Slifkin in 1949, “A Study of the Control of Differentiation: The Proportions of Stalk and Spore Cells in the Slime Mold Dictyostelium discoideum”, the researchers found that when the temperature of the environment of D. discoideum was altered, the fruiting body was also altered. While there was no significant reaction to temperatures being lowered, when they raised the temperature, they found that the proportion of stem cells in the fruiting body decreased, especially when the temperature decreased drastically. This means that the multicellular organism changed its anatomy by altering the state of the unicellular organisms, dictating them to be spore mass cells more often than stem cells. The ability of unicellular organisms to change based on their environment and thus optimize their multicellular forms is incredibly helpful, and magnificently strange. This is the reason that members of the genus Dictyostelium have always been, and continue to be, a fascinating subject for systems biologists.

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