Researchers decide to study the effects of chemicals on heart rates. They decide to expose Daphnia magna to different chemical treatments. The Daphnia magna is a form of crustacean that is easily studied in a laboratory environment. In the study, Daphnia magna were placed under a microscope in a saline solution. The Daphnia magna were then exposed to differing substances to observe their effects on physiology and disruption of homeostasis. After the chemical treatments were added to the solution, the Daphnia magna’s heart rate was observed and recorded in beats per minute, as seen in Figure 1.

Figure 1

Heart rates are moderated by an organism's sympathetic and parasympathetic nervous system. The sympathetic nervous system increases heart rate and mobilization in the fight-or-flight response, while the parasympathetic slows and relaxes and organism's activities in the rest-and-digest phase. Which of the following chemicals from Figure 1 contribute to an organism's fight-or-flight response?

Ecological succession refers to the observable change of the species composition of an ecological community over a period of time. This phenomenon is also known as forest succession. It is a process that begins with the colonization of a habitat by robust pioneer species that can survive inclement and harsh environments. Pioneer species are characterized by small size and rapid reproduction of many offspring. Over successive generations these species are replaced with increasing complexity until the ecosystem reaches a self-perpetuating climax community that ceases to vary in composition.

Researchers decide to quantify the ecological succession of a particular deciduous forest. Figure 1 is a representation of an ecological community over a forty-year period. The bars on the graph represent the percentage of the forest community that is made up by a particular species. 

What is the species composition of the forest at the one year time interval?

Ecological succession refers to the observable change of the species composition of an ecological community over a period of time. This phenomenon is also known as forest succession. It is a process that begins with the colonization of a habitat by robust pioneer species that can survive inclement and harsh environments. Pioneer species are characterized by small size and rapid reproduction of many offspring. Over successive generations these species are replaced with increasing complexity until the ecosystem reaches a self-perpetuating climax community that ceases to vary in composition.

Researchers decide to quantify the ecological succession of a particular deciduous forest. Figure 1 is a representation of an ecological community over a forty-year period. The bars on the graph represent the percentage of the forest community that is made up by a particular species.

What are the least dominant species at the forty-year interval?

Ecological succession refers to the observable change of the species composition of an ecological community over a period of time. This phenomenon is also known as forest succession. It is a process that begins with the colonization of a habitat by robust pioneer species that can survive inclement and harsh environments. Pioneer species are characterized by small size and rapid reproduction of many offspring. Over successive generations these species are replaced with increasing complexity until the ecosystem reaches a self-perpetuating climax community that ceases to vary in composition.

Researchers decide to quantify the ecological succession of a particular deciduous forest. Figure 1 is a representation of an ecological community over a forty-year period. The bars on the graph represent the percentage of the forest community that is made up by a particular species.

What is the most dominant forest species at the five-year mark?

Ecological succession refers to the observable change of the species composition of an ecological community over a period of time. This phenomenon is also known as forest succession. It is a process that begins with the colonization of a habitat by robust pioneer species that can survive inclement and harsh environments. Pioneer species are characterized by small size and rapid reproduction of many offspring. Over successive generations these species are replaced with increasing complexity until the ecosystem reaches a self-perpetuating climax community that ceases to vary in composition.

Researchers decide to quantify the ecological succession of a particular deciduous forest. Figure 1 is a representation of an ecological community over a forty-year period. The bars on the graph represent the percentage of the forest community that is made up by a particular species.

What is the dominant species of the forest at the forty-year interval?

Ecological succession refers to the observable change of the species composition of an ecological community over a period of time. This phenomenon is also known as forest succession. It is a process that begins with the colonization of a habitat by robust pioneer species that can survive inclement and harsh environments. Pioneer species are characterized by small size and rapid reproduction of many offspring. Over successive generations these species are replaced with increasing complexity until the ecosystem reaches a self-perpetuating climax community that ceases to vary in composition.

Researchers decide to quantify the ecological succession of a particular deciduous forest. Figure 1 is a representation of an ecological community over a forty-year period. The bars on the graph represent the percentage of the forest community that is made up by a particular species.

What is the least dominant species of the ten-year interval?

Many motile organisms exhibit “fight or flight” responses in order to survive and reproduce. Aggressive posturing and combative behavior are important for the reproductive success and the formation of pack hierarchies of some species. Submissive actions and retreats permit other species the ability to evade capture or danger and enhance survival capabilities. Scientists have debated about the mechanics and moderation of these behaviors within organisms. Two studies regarding this behavior were performed.

Study 1

Researchers decided to study crayfish, a type of freshwater arthropod, in an aquarium. They placed two crayfish opposing one another in an enclosed space. The crayfish were divided by an opaque screen that inhibited their ability to notice one another. The screen was lifted and the crayfish were permitted to interact with one another. The scientists observed their interactions and noted the crayfish's submissive and aggressive behaviors. The scientists noticed that more dominant and aggressive behaviors correlated with larger sized individuals. Their observations indicate that large size and aggression are traits actively selected for within the crayfish population and are necessary for survivorship and reproductive success.

Study 2

Researchers in this study suggest that aggressive behaviors are linked to chemical messengers. They attempted to alter the crayfish’s lateral giant escape reaction through chemical manipulation. They injected crayfish with serotonin, an aggression stimulant, and octopamine, a natural facilitator of the flight response. They monitored and recorded the crayfish’s response to aggressive stimuli (see Figure 1). The researchers concluded that the crayfish escape response is significantly different in the chemical trials in comparison to the control trial that observed the injection of an inert saline solution into the arthropods.

Figure 1

In Study 2, when were the serotonin treated crayfish least likely to exhibit the lateral giant response reaction?

Many motile organisms exhibit “fight or flight” responses in order to survive and reproduce. Aggressive posturing and combative behavior are important for the reproductive success and the formation of pack hierarchies of some species. Submissive actions and retreats permit other species the ability to evade capture or danger and enhance survival capabilities. Scientists have debated about the mechanics and moderation of these behaviors within organisms. Two studies regarding this behavior were performed.

Study 1

Researchers decided to study crayfish, a type of freshwater arthropod, in an aquarium. They placed two crayfish opposing one another in an enclosed space. The crayfish were divided by an opaque screen that inhibited their ability to notice one another. The screen was lifted and the crayfish were permitted to interact with one another. The scientists observed their interactions and noted the crayfish's submissive and aggressive behaviors. The scientists noticed that more dominant and aggressive behaviors correlated with larger sized individuals. Their observations indicate that large size and aggression are traits actively selected for within the crayfish population and are necessary for survivorship and reproductive success.

Study 2

Researchers in this study suggest that aggressive behaviors are linked to chemical messengers. They attempted to alter the crayfish’s lateral giant escape reaction through chemical manipulation. They injected crayfish with serotonin, an aggression stimulant, and octopamine, a natural facilitator of the flight response. They monitored and recorded the crayfish’s response to aggressive stimuli (see Figure 1). The researchers concluded that the crayfish escape response is significantly different in the chemical trials in comparison to the control trial that observed the injection of an inert saline solution into the arthropods.

Figure 1

In Study 2, when were the octopamine treated crayfish most likely to exhibit the a lateral giant response reaction?

Many motile organisms exhibit “fight or flight” responses in order to survive and reproduce. Aggressive posturing and combative behavior are important for the reproductive success and the formation of pack hierarchies of some species. Submissive actions and retreats permit other species the ability to evade capture or danger and enhance survival capabilities. Scientists have debated about the mechanics and moderation of these behaviors within organisms. Two studies regarding this behavior were performed.

Study 1

Researchers decided to study crayfish, a type of freshwater arthropod, in an aquarium. They placed two crayfish opposing one another in an enclosed space. The crayfish were divided by an opaque screen that inhibited their ability to notice one another. The screen was lifted and the crayfish were permitted to interact with one another. The scientists observed their interactions and noted the crayfish's submissive and aggressive behaviors. The scientists noticed that more dominant and aggressive behaviors correlated with larger sized individuals. Their observations indicate that large size and aggression are traits actively selected for within the crayfish population and are necessary for survivorship and reproductive success.

Study 2

Researchers in this study suggest that aggressive behaviors are linked to chemical messengers. They attempted to alter the crayfish’s lateral giant escape reaction through chemical manipulation. They injected crayfish with serotonin, an aggression stimulant, and octopamine, a natural facilitator of the flight response. They monitored and recorded the crayfish’s response to aggressive stimuli (see Figure 1). The researchers concluded that the crayfish escape response is significantly different in the chemical trials in comparison to the control trial that observed the injection of an inert saline solution into the arthropods.

Figure 1

Which of the crayfish in Study 2 are most likely to exhibit territorial behaviors?

Many motile organisms exhibit “fight or flight” responses in order to survive and reproduce. Aggressive posturing and combative behavior are important for the reproductive success and the formation of pack hierarchies of some species. Submissive actions and retreats permit other species the ability to evade capture or danger and enhance survival capabilities. Scientists have debated about the mechanics and moderation of these behaviors within organisms. Two studies regarding this behavior were performed.

Study 1

Researchers decided to study crayfish, a type of freshwater arthropod, in an aquarium. They placed two crayfish opposing one another in an enclosed space. The crayfish were divided by an opaque screen that inhibited their ability to notice one another. The screen was lifted and the crayfish were permitted to interact with one another. The scientists observed their interactions and noted the crayfish's submissive and aggressive behaviors. The scientists noticed that more dominant and aggressive behaviors correlated with larger sized individuals. Their observations indicate that large size and aggression are traits actively selected for within the crayfish population and are necessary for survivorship and reproductive success.

Study 2

Researchers in this study suggest that aggressive behaviors are linked to chemical messengers. They attempted to alter the crayfish’s lateral giant escape reaction through chemical manipulation. They injected crayfish with serotonin, an aggression stimulant, and octopamine, a natural facilitator of the flight response. They monitored and recorded the crayfish’s response to aggressive stimuli (see Figure 1). The researchers concluded that the crayfish escape response is significantly different in the chemical trials in comparison to the control trial that observed the injection of an inert saline solution into the arthropods.

Figure 1

Which of the crayfish in Study 2 are least likely to exhibit territorial behaviors?