Animal Behaviour: Biology 3401

Transcription

1 1 Animal Behaviour: Biology 3401 Laboratory 2: The effects of physical and biological factors on various invertebrate organisms Parts of this lab were taken from or adapted from: Glase, J. C., M. C. Zimmerman, and J. A. Waldvogel Investigations in orientation behavior. Pages 1-26, in Tested studies for laboaratory teaching, Volume 6 (C. A. Goldman, S.E. Andrews, P.L. Hauta and R. Ketcham, Editors). Proceedings of the 6th Workshop/Conference of the Association for Biology Laboratory Education (ABLE), 161 pages. Questions to Prepare You for this Laboratory What are three types of orientation stimuli that can be sensed by some organisms but not humans? What characterizes a taxis orientation response? What characterizes a kinesis orientation response? Is the manner in which you would locate the source of an odor in a dark room a taxis, a kinesis, both, or neither? Is the manner in which you would locate the source of a sound in a dark room a taxis, a kinesis, both, or neither? Introduction Humans have been aware of animal orientation, migration, and navigation for thousands of years. Whole civilizations have thrived or perished based on their understanding of the movements made by principal animal food sources. Yet, it was not until early in the 20th century that a rigorous analysis of orientation mechanisms began, when our knowledge of sensory systems and how other animals detect the world improved considerably. Orientation refers to the spatial organization of movements. Since movements are elements of behavior, orientation and behavior are intimately associated. For simplicity, we will define behavior as any overt manifestation of life by an animal, especially one that takes the form of movements. A behavior pattern is the fundamental unit of behavior, and is defined as a sequence of movements characterized by a specific configuration in time and space. This underscores the special significance that spatial organization has for behavior. Every behavior is spatially oriented in some way. Whether an animal walks, grooms, catches prey, or interacts with a social partner, "where" and "in which direction" are indispensable features of its behavior pattern. Thus, we can define orientation as the process that animals use to organize their behavior with respect to spatial features. The specific orientation systems used by an animal correspond to the features of its environment. Many terrestrial organisms are sensitive to humidity levels, and are therefore capable of orienting with respect to moisture gradients. But humidity is an environmental feature that is not relevant in a totally aquatic habitat, and as a result animals that live in water must use physical gradients based on other parameters (e.g., temperature or salinity) to help direct their movements. Some orientation stimuli are available to both terrestrial and aquatic organisms; these include gravity, light and

2 2 magnetism. This laboratory exercise will allow you to investigate orientation behavior in a variety of animals. It will help you understand the scientific method by giving you experience in conducting and interpreting data involving animal orientation. Orienting Stimuli In orientation studies, one first attempts to identify the nature of the stimuli to which the animal is orienting. Light, gravity, sound, and mechanical stimuli, as well as temperature, chemical, and moisture gradients are all likely candidates. As with a moth flying into a candle, the nature of the orienting stimulus may be clearly apparent. However, if the animal is orienting to a stimulus for which humans have no receptor organs, identification of that stimulus will be much more difficult. Orientation to ultraviolet and polarized light, magnetism, electrical fields, and some acoustic stimuli are of this sort. Frequently, organisms respond simultaneously to several stimuli while orienting. Thus, one must be cautious in interpreting observations of orientation behavior since the stimulus most obvious to human senses may not be the most important factor determining the animal's behavior. Frequently an orienting stimulus also elicits a behavioral response. For example, in prey-catching and courtship behavior, the animal often first orients toward the prey or mate, then performs the appropriate behavior to capture the prey or attract the mate. The presence of the prey or potential mate in the environment causes the animal to orient appropriately as well as to perform other behaviors. At the same time that an animal is stalking prey or courting, it is also using gravity as a stimulus for body orientation relative to the earth. As a tuna pursues a mackerel in the open ocean, the mackerel elicits and orients the predatory behavior of the tuna, but gravity and light stimuli are also used by the tuna for general body orientation. In addition to species differences for a given orientation behavior, the nature of the orienting stimulus itself may vary as a function of the animal's age. Many nestling birds, for example, show a gaping response which elicits parental feeding. When the nestlings first hatch they are blind, and the gaping response is released by mechanical or auditory stimuli provided by the parent birds. The nestlings gape vertically, with gravity being the main orienting stimulus. Later, after a nestling can see, the sight of the parent bird not only elicits the gaping response, but also orients it. Classification of Orientation Responses The ways that animals orient to their environment are diverse, and certain schemes have been developed to classify these responses in reference to underlying similarities. The classification system presented in this laboratory was first suggested by Fraenkel and Gunn ( The Orientation of Animals). Kinesis One important distinction that Fraenkel and Gunn make depends on whether the animal's body is oriented with respect to the stimulus source. A movement that does not involve orientation with reference to a stimulus source is known as a kinesis where the stimulus produces either a change in the speed of the animal's movement (orthokinesis) or in the animal's turning rate (klinokinesis). These two responses effectively change the

3 3 position of the animal with respect to the stimulus source. Several examples should clarify this point. Isopods (terrestrial crustaceans) prefer moist habitats. In some species, as the relative humidity of the environment increases, the amount of time the animal is stationary also increases. This response tends to keep an isopod in damper areas. As another example, some insects cannot detect the direction of an odor gradient, but their rate of locomotion varies with the strength of the odor. Thus, if an insect moves rapidly at low concentrations of a chemical and slowly at high concentrations, it should eventually arrive at the source of the odor. The human body louse (Pediculus corporis) finds its host by a kinetic response to a number of stimuli including temperature, humidity, and odor. When in a favorable environment with respect to these stimuli, the louse travels in straight lines. However, if it encounters an unfavorable environment, it turns until a favorable environmental zone is once again encountered. In summary, a kinesis involves quantitative variations in an animal's speed or turning rate with no fixed orientation of the body relative to the stimulus source. Taxis In a taxis, the animal's body is oriented in some linear manner relative to a stimulus; either directly toward it, directly away from it, or at a fixed angle to it. Locomotion may or may not be involved in a taxis. This kind of response may be shown for light, heat, moisture, gravity, sound, chemicals, or other stimuli. For the next two weeks you will be examining the effect of various physical and biological stimuli on the behavior of a variety of invertebrates. Materials and Methods A. Physical Factors 1. Humidity and Light Preference in pillbugs These terrestrial crustaceans, sometimes called pillbugs (Armadillium sp.), are common inhabitants of leaf litter and soil. They feed on decaying organic material as well as algae, moss, and bark. Isopods have a pair of compound eyes, two pairs of antennae (although only the second pair is prominent), and seven pairs of legs. When disturbed or desiccated they will roll up into a ball, looking rather pill-like. Experiment one: This experiment will be conducted in an elongated Plexiglas chamber that can be used to collect quantitative data on the response of individuals to light, humidity, or a combination of these stimuli (Fig. 1). At one end there is anhydrous CaCl 2 (a desiccant) and a wet paper towel in the other end. This sets up a humidity gradient that we are assuming is changing consistently over the length of the apparatus. For this part of the experiment, observe the animals under RED LIGHT (most invertebrates have a lower sensitivity to red light). Place 10 individuals in the chamber via the central stoppered hole (be careful not to introduce debris into the chamber). Every minute count the number of pillbugs in each section of the chamber (there are paper sheets to place under the chamber to indicate which section the bug it in).

4 4 Enter the data on the sheet on the next page (Data table 1). Continue counting for 30 minutes. Experimental Setup for Pillbug Choice Experiments Desiccant (CaCl ) Introduce pillbugs here Moistened paper towel SECTION Dry Humid

5 5 Data table 1 Data Table for Pillbug Wet vs. Dry Choice Experiment Dry Humid Section Observation # Mean S.E.

6 6 Experiment 2. This experiment is essentially a repeat of Experiment 1 but testing the response of pillbugs to light vs dark. Use a NORMAL WHITE LIGHT for this experiment. Place the black plexiglass covers over one half of the chamber to create the dark end. Introduce 10 pillbugs into the chamber as before and wait one minute before beginning observations. After each minute, count the number of animals in the light sections (to get the number in the dark you have to count the number in the light section and subtract from 10 ). Enter the data in Data Table 2. Continue counting for a minimum of 10 minutes and stop when the number of animals in one section is 0 for three successive minutes. The Interaction of Factors After you have gained some insight into the pillbug's response to humidity and illumination independently (and have collected enough data to support your views!), you can examine the interplay between these two stimulus types. Is the response to humidity changed under conditions of high illumination? What if the individuals are offered a brightly illuminated, humid environment versus a dark, dry environment? Experiment 3 In this experiment, you will be looking at the interaction between humidity and light in the response of pillbugs. Again, use a NORMAL WHITE LIGHT for this experiment. Set up the experiment as in experiment 1 but put one end of the chamber (either the humid or dry end) into the opaque chamber. Introduce ten pillbugs into the chamber and wait one minute before beginning observations. After each minute, count the number of animals in the dark and in the light sections. As before, continue counting for a minimum of 10 minutes and stop when the number of animals in one section is 0 for three successive minutes. Enter the data into Data table 3. Repeat the experiment but this time switch the end the chamber that is in the opaque chamber. Introduce ten fresh (i.e. untested) pillbugs into the chamber and repeat the experiment as above. Experimental Setup for Pillbug Combined Choice Experiments Desiccant or Moistened paper towel Introduce pillbugs here Desiccant or Moistened paper towel Opaque chamber SECTION

7 7 Data table 2 Data Table for Pillbug Light vs. Dark Choice Experiment Section Dark Light Observation # Mean S.E.

8 8 Data table 3 Data Table for Pillbug Combination Factors Experiment Observation # Dry -Dark Humid Light Dry Light Humid - Dark Mean S.E.

9 9 2. Geotaxis in snails/slugs Background: Gastropods (including limpets, whelks, slugs and snails) generally move slowly and sluggishly. For that reason, their locomotion is relatively easy to study. Under certain conditions they move consistently in one direction, and are apparently welloriented with respect to gravity. Also, the direction of their movements often seems to be influenced by the paths taken by other nearby snails. This portion of the laboratory concerns the study of three aspects of the locomotory behaviour of a terrestrial snail Helix aspersa: (1) undisturbed movements, (2) gravity responses, and (3) the tendency to follow trails left by other individuals. Helix aspersa is commonly found in gardens, hedges and woodlots. This snail is normally inactive during daylight and under dry conditions, and moves and feeds especially at night or after rain. It feeds on living vegetable material, from which fragments are abraded by means of a toothed radula. In winter and during prolonged dry periods, Helix seals up the aperture of its shell with a film of mucus hardened with calcium phosphate. Many, if not all snails, will be quiescent at the start of the laboratory session and it is essential to stimulate them and have them about actively immediately before use. This is best done by immersing the snails in tepid (lukewarm) water for a few minutes. As soon as a snail shows signs of activity it should be removed from the water, dabbed dry and introduced to the experimental set-up. Handle the snails gently, especially when lifting them up from an attached position. They are not likely to move in a natural, consistent way if you roughly tear them loose from a substrate. PART 1: Movements in relation to gravity (geokineses/geotaxis) are to be studied as follows. If Helix aspersa (the land snail) is available use Helix. Otherwise, use the slugs available in lab. Place a fresh slug on the centre of a clean plexiglass plate that has a grid of squares drawn on the reverse side. Clamp the plate in a vertical position with one edge on the bench top (angle of inclination=90 o ). As soon as the slug begins, start a stopwatch, and plot its course to scale on a separate sheet of graph paper. After 5 minutes, or when the slug has reached the edge of the glass plate (whichever occurs first), remove it. Determine the angle of orientation of its path with respect to the side of the plate in contact with the bench. Do this by drawing a straight line on the graph paper that represents as accurately as possible the direction of the slug s path. If a sharp change in direction occurred during the test, two separate angles of orientation should be determined. By using a piece of string to estimate the distance travelled by the snail, and the time between start and end of the test, determine its speed of movement (cm/min).

10 10 Repeat the above procedure with two more slugs (thus yielding 3 replicates), being sure to wash the glass plate thoroughly after running each animal. Then change the angle of inclination of the plane to 45 o from the horizontal and repeat above procedure with the same three slugs (or fresh slugs if the supply is large enough). Finally, repeat the steps again with the plate at 75 and 25 o inclination. 3 slugs each for a total of 12 separate tests. Record all your data in Data Table 4. Prepare a graph showing the mean angle of orientation and another graph showing the mean speed of movement of your slugs in relation to the angle of inclination of the plate. Each mean value should be based on 3 replicate measurements. In discussing your results, consider the following: What are the sensory structures that enable a slug to detect changes in gravity? Where are they located? What are some environmental variables that could affect the behavior of slugs in this laboratory exercise? What might be the significance of the observed responses to the slugs in nature? Are they taxes or kineses? Experimental set-up for snail geotaxis experiment

11 11 Data Table 4: Data table for slug geotaxis experiment Plate angle (degrees) Slug # Slug path angle (degrees) Speed (cm/min) Distance (cm) PART 2: Chemoreception in slugs (trail following) Purpose: to study trail following by determining the degree to which the mucous trails of a blazer and a follower snail coincide. The tendency for one animal to follow the recently laid mucous trail of another conspecific has been demonstrated in several gastropods, including terrestrial snails. Examine trail following in slugs as follows. Method: Place one active slug (the trail blazer ) at the centre of a piece of clean plexiglass lying flat on the bench top. Plot to scale the path of this slug until it has moved 15-20cm (within 5-8 minutes). Then remove it and place a second slug (the follower ) at the same starting point, and oriented in the same direction as the blazer. Observe and plot the path of the follower on the same graph paper until it has moved at least as far as the blazer did. Remove the follower and determine the coincidence index (C.I.) of the two mucous trails using the following equation: C.I. = Lc/(Square root of (Lb X Lf)) Where Lc is the length of the follower trail that coincides with the blazer trail, Lb is the length of the blazer trail and Lf is the length of the follower trail. Use string to estimate each of these distances.

12 12 Repeat the above procedure with two more pairs of slugs, making sure that the glass plate is washed between tests. Summarize your data in a table (Data table 5), showing values of Lc, Lb, Lf and C.I. for each pair of slugs and an overall mean (SD) C.I. Discuss the possible functional significance of trail following in a slug. Data table 5: Data from trail following in slugs Trial # Lc Lb Lf CI Mean SEM 3. Chemoreception in flour beetles (Tenebrio molitor; effect of pheromones on mate attraction) See additional hand-out. ANIMAL BEHAVIOUR: BIOLOGY 3401 Part of Lab 2: Physical and Biological factors (additional hand-out)- PHEROMONES AND MATE ATTRACTION IN THE FLOUR BEETLE, Tenebrio molitor* INTRODUCTION: Many insects possess extremely well developed olfactory organs and in consequence, rely upon chemoreception to direct such biologically essential activities as location of food, mate or oviposition site, induction of copulatory behaviour and alarms signaling the approach of a predator. As well, exchange of chemical information between insects of the same species can, in some cases, bring about physiological changes that result in modification of the insect s pattern of development. The term pheromone was used by scientists in the late 1950 s who were studying chemical communication in insects. They applied the term to any compound that is released by one member of a species to carry information to another of the same species. Studies on gypsy moths showed just how strong the physiological response to these

13 13 chemicals can be. They were able to fool male moths into copulating with anything from oak leaves to filter paper by simply spraying the surface with the female pheromone. Extensive work has been done on insect pheromones, including studies on the specificity and degree of response to natural and synthetic pheromones. Studies show that for the purpose of mate location, usually the female (less often, the male) releases a pheromone to attract the opposite sex. In some insects, copulatory behaviour following mate location is induced by an aphrodisiac pheromone released by either the male or female, depending on species. Copulation though is not the sole purpose for pheromone release in any species. Other examples of pheromone use include: attraction to a feeding site (e.g. trail laying in ants); alarm pheromones, produced when a social insect is threatened in some way; control of long-term developmental processes (e.g. maintenance of caste structure in termite colonies). In most insects, pheromones are produced by epidermal cells compacted into discrete glands and concentrated in defined areas beneath the cuticle. * Adapted from: Physiology Laboratory Manual, 1993, T. Rand, Saint Mary s University. Most pheromone communication is accomplished by mixtures of compounds ( multicomponent pheromones or pheromone blends ) and it is the relative proportion of constituents comprising the blend (as well as the sensitivity of the receptors of the receiving individual) that differs among species and confers an element of specificity to the response. An industry is being developed around the potential use of pheromones for insect control purposes. Pheromone-baited traps can be used to: (a) monitor the presence of a pest in the ecosystem, to determine whether or not it would be an appropriate time to apply insecticides; (b) remove large numbers of pests directly from the ecosystem (masstrapping); (c) confuse natural pest populations by saturating the atmosphere with pheromone and, thus, preventing mate location. In today s laboratory, you will be studying sexual attraction via pheromones in one insect: the meal worm beetle (also known as the flour beetle), Tenebrio molitor.

14 14 You will examine the capacity of female insects, and extracts prepared from virgin females, to attract males and also the female response to live males and to male extracts. METHODS: A. General: Because Tenebrio is photosensitive and actively avoids the light, the entire laboratory will be carried out under red light to which the beetles are less sensitive. As you obtain the data for your group, enter it in the Tables provided and on the blackboard. Today s laboratory relies heavily on class data. Tenebrio were sexed and segregated as pupae. Pheromone extracts of Tenebrio were prepared recently. There are two parts to this lab assessing the male response to female pheromones and the female response to male pheromones. A. Male response to female pheromones For each trial, you will be using a Petri dish, the bottom of which is lined with a sheet of filter paper. Put a single male in the Petri dish and allow him 5 minutes to acclimate. Take a glass bead from the ethanol and dry it off by repeatedly shaking it and wiping it with a Kimwipe tissue. Avoid handling the tip of the bead with your fingers. Dip the end of the bead in the experimental fluid and let it air dry for 30 seconds. Place the bead centrally on the filter paper in the petri dish and replace the cover. Record the response. If there is no response in 5 minutes, terminate the trial and get a new male. ORDER OF EXPERIMENTAL FLUID: To save on filter paper, work your way up in concentration. Start with the ethanol control, then go from the weakest extract up to the strongest extract. You MUST change the filter paper before the trial with the Bornyl Acetate (female cockroach pheromone). To rate the male response, use the following scale: 0 - no attraction 1 - some attraction, circles the glass bead 2 - some attraction, touches the glass bead, more than once

15 more attraction, stays on the glass bead, or repeatedly returns and touches it; moves along the length, keeping contact with it 4 - attempts copulation or shows copulatory behaviour Response in the male upon perception of a female begins with the beetle waving his antennae. He will then extend his prothoracic legs, resulting in raising his body, the rearing and antenna waving becoming jerky and faster. Copulatory response involves the male, once in contact with the female, stroking her with his antennae, then climbing up on her quickly while continuing to stroke her sides with his front legs. He will then bend his abdomen down and around the end of the female (or the bead) to make genital contact. He continues to beat against her back with his antennae during copulation. A positive behavioral response may also be displayed by the beetle crawling along or staying affixed to the bead, making no attempt to leave it. You will be testing THREE males with FIVE different solutions. These are: 1. an untreated glass bead (control) 2. female pheromone extract (A, B, or C) (these solutions are of graded concentration expressed as number of insects extracted/ml, solutions are: A, 2.5/ml; B, 0.625/ml; C, 0.156/ml).. 3. bornyl acetate (a female cockroach pheromone) In each test, you should note which level of response that the male attained on the scale above. TIP: Have three petri dishes going at once with one male in each dish. Each male must be exposed to all 5 solutions. Remember to expose the male to these solutions in the appropriate order. B. Female response to the male pheromone Female response is far more passive than the male response and thus must be rated differently. When a female detects a male pheromone, she tends to slow down but she does exhibit some rearing and antenna waving. Studies have shown that females will gather in areas where male pheromone has been placed. We will use these two criteria to gauge female response.

16 16 We are using chambered models (Fig. 1) to determine response in the female. Two virgin females are placed in each of the six outer chambers and allowed 30 minutes to acclimate. At 15 and 30 minutes in the acclimation period, examine the activity and distribution of females in the chamber. To score the distribution, divide the entire chamber into two sections (near and far zones, as defined by concentric circles (see Fig. 1). Note the total number of females in the near and far zone in each chamber. To score the activity, record the number of seconds each female spends walking in a 30 sec. observation period. After 30 minutes, place one of the following stimuli in the central chamber of the apparatus. a live male WEDNESDAY LAB a bead dipped in male extract WEDNESDAY LAB a clean glass bead (control) THURSDAY LAB a bead dipped in female extract - THURSDAY LAB. You will now be monitoring the chamber for 30 minutes. Every 3 minutes note the position of the females (i.e. whether each is in the near or far zone). At 10, 20, and 30 minutes record the activity as above. far zone near zone central chamber Fig. 1. Top view of the choice chamber used in female choice experiment. Each section of the chamber is divided into a near and far zone to assess the attraction of females to the stimulus in the central chamber.

17 17 STATISTICAL ANALYSES The part of analyzing this lab that will be the most challenging is the statistics to use when assessing the response of males. Male response has been scored qualitatively (as opposed to quantitatively) meaning that the responses have been rated on a scale from 0 to 4. These kinds of data are called ordinal and must be analyzed using non-parametric tests. In this case, we are doing a series of tests on ordinal data and the appropriate test is a Komolgorov-Smirnov test (or KS test). The logic behind a KS test is not unlike a Chi 2 test. The first step is to sum the data across all trials for each experiment condition. Then do the series of calculations as indicated in the following table Response Observed Frequency Expected Frequency Cumulative Observed Frequency Cumulative Expected Frequency Absolute value of the difference The critical KS statistic is the largest of the absolute values of the difference between the cumulative observed and expected frequencies or K max = 8. Look this value up in the table provided at the end of the handout. In the example above, it will be for 5 classes of data and 35 samples.

18 Summary of lab procedure 18 READ THE LAB!!! Set up trials for male response Petri dishes and glass beadss -control -female pheromone extract (each of 3 concentrations) - bornyl acetate (a female cockroach pheromone) Score the response according to the 4 point scale provided and put the results on the board Set up trials for female response -put females into chambers -1/2 hour acclimation (note position and activity) - 1/2 hour test period with stimulus Score the activity and distribution results and put the results on the board THURSDAY LAB - Use live male & male extract FRIDAY LAB - Use water & female extract

19 19 REFERENCES *August, C. J. (1971) The role of male and female pheromones in the mating behaviour of Tenebrio molitor. J. Insect. Physiol. 17: Chapman, R.F. (1982) Exocrine glands, pheromones and defensive secretions. In: The Insects, Structure and Function. 3rd Edition, Harvard University Press, pp *Happ, G. M. (1970) Maturation and the response of male Tenebrio molitor to the female sex pheromone. Ann. Ent. Soc. Amer. 63: *Happ, G. M and Wheeler, J. (1969). Bioassay, preliminary purification, and effect of age, crowding, and mating on the release of Sex pheromone by female Tenebrio molitor. Ann. of Entomological Soc. of America: 62: *Tanaka, Y., H. Honda, K. Olsawa & I. Yammoto. (1986) A sex attractant of the yellow meal worm, Tenebrio molitor L. and its role in mating behaviour. J. Pesticide Sci. 11: *Tschinkel, Walter, C. Willson and H.A. Bern. (1967) Sex pheromone of the meal worm beetle. J. Exp. Zool. 167: Seabrook, W.D. and L.J. Dyer. (1983). Pheromones in insect control. In: Endocrinology of Insects, pp Alan R. Liss. inc. NY. *These papers are available on the course website at

20 20 DATA SHEETS 1. MALE RESPONSE (Test 3 males in each condition!!!) CONDITION Control Extract A Extract B Extract C Bornyl acetate RESPONSE SCORE*** ***Record the number of males that reach each level of response for each condition. 2. FEMALE RESPONSE A. ACCLIMATION PERIOD IN CHAMBER POSITION OF FEMALES NUMBER IN NEAR ZONE 15 MIN. NUMBER IN FAR ZONE 30 MIN. ACTIVITY OF FEMALES (during acclimation period) 15 MIN 30 MIN FEMAL FEMAL FEMAL E E E Seconds(/3 0) spent Seconds(/3 0) spent Seconds(/3 0) spent FEMAL E Seconds(/3 0) spent

21 21 2. FEMALE RESPONSE A. TESTING PERIOD IN CHAMBER Male (THURSDAY) OR Clean glass bead (FRIDAY) POSITION OF FEMALES NUMBER IN NEAR ZONE NUMBER IN FAR ZONE ACTIVITY OF FEMALES 10 MIN 20 MIN MIN

22 22 B. TESTING PERIOD IN CHAMBER Male Extract (THURSDAY) OR Female Extract (FRIDAY) POSITION OF FEMALES NUMBER IN NEAR ZONE NUMBER IN FAR ZONE ACTIVITY OF FEMALES 10 MIN 20 MIN MIN

23 23 Assignment: Every week you will have an assignment to complete. The lab assignments are handed in the following week in lab. Make sure you are doing the right assignment the assignments for each week depend on which group you are placed in (and therefore, which exercises you completed). This is detailed below. Group work and assignments: Group A Week 1 Exercise: Light and humidity preference in pillbugs AND snail/slug geotaxis and trail following Assignment: Write an abstract for the work with the pillbugs (This means you must look at the data and include information on the results of the study and the implications of this work. Abstracts tend to be tricky, read abstracts from other papers to get an idea of content and layout.) AND a results section for the work with the snails. This is more than graphs and tables you should have written results. See example papers. No, really. Go look at them. Perhaps now Week 2 Exercise: Chemoreception in flour beetles Assignment: Write a discussion for the pheromone work with the flour beetles. Group B Week 1 Exercise: Chemoreception in flour beetles Assignment: Write a discussion for the pheromone work with the flour beetles. Week 2 Exercise: Light and humidity preference in pillbugs AND snail/slug geotaxis and trail following Assignment: Write an abstract for the work with the pillbugs (This means you must look at the data and include information on the results of the study and the implications of this work. Abstracts tend to be tricky, read abstracts from other papers to get an idea of content and layout.) AND a results section for the work with the snails. This is more than graphs and tables you should have written results. See example papers. No, really. Go look at them. Perhaps now