Unit 8.1-2
Responses to the Environment
Behaviors:
They arise from interactions with the environment and serve various purposes.
Behavioral Ecology:
Developed in the 1970s, a significant discovery led to a Nobel Prize in Physiology, establishing ethology, which is the study of how evolutionary processes shape behaviors.
Behavior Definition:
Animal behavior is defined as the response to an internal or external stimulus.
The nature vs. nurture debate addresses genetic and environmental influences on behavior.
Behaviors are crucial for survival and reproduction, and they are subject to natural selection.
Understanding Behavior - Proximate vs. Ultimate Causes:
Proximate Cause:
Refers to how a behavior occurs or is modified.
Involves understanding the immediate stimulus and how experiences affect behavior during growth.
Ultimate Cause:
Explains why a behavior occurs in the context of natural selection.
Investigates how behavior aids survival and reproduction and its evolutionary basis.
Practice Problem Example:
Zebras may react to drinking water by having some watch for predators while others drink.
Proximate Causes:
The immediate stimulus is the need for water; the watching zebras help protect those drinking.
Ultimate Causes:
This behavior increases survival by reducing predation risk while drinking.
Types of Behavior:
Innate Behaviors:
Developmentally fixed and instinctive, they do not require learning.
They remain consistent regardless of experience or environment.
Kinesis: A form of movement that is non-directional and occurs in response to stimuli, resulting in changes in activity level, such as increased movement in unfavorable conditions.
Taxis: A directed movement towards or away from a stimulus, allowing organisms to actively respond to environmental cues.
Phototaxis: A movement towards light sources, facilitating beneficial processes such as photosynthesis in plants and aiding organisms in finding optimal hab itats.
Chemotaxis: A movement towards or away from chemical stimuli, which is essential for organisms to locate resources like food or to avoid harmful substances.
Geotaxis: A form of taxis in which organisms move in response to gravity, helping them orient themselves appropriately in their environment, such as roots growing downward and shoots growing upward.
Learned Behaviors:
These evolve based on environmental experiences and exhibit variability across populations.
Examples of Behaviors:
Fixed Action Patterns (FAPs):
Sequence of unlearned acts linked to specific stimuli.
Examples include male stickleback fish becoming aggressive when seeing the color red.
Learning Types:
Imprinting:
A long-term response occurring during a sensitive development period, like ducklings following their mother.
Spatial Learning:
Animals establish memories based on their surroundings, such as birds remembering where they hid their nests.
Associative Learning:
Linking one feature to another, e.g., monarch butterflies associated with foul taste.
Social Learning:
Learning through observation, evident in chimpanzees breaking nuts.
Natural Selection:
Favors behaviors enhancing survival and reproduction, including foraging and mating behaviors.
Cooperative Behaviors:
Increase fitness through predator warnings and altruistic actions seen in naked mole rat colonies.
Responses in Plants:
Plants can react to light (phototropism), development influenced by day length (photoperiodism), and use physical and chemical defenses against herbivores.
Example: Lima bean plants release volatile chemicals to inform neighbors of herbivore presence.
Soil pH can alter flower coloration, such as hydrangea blooms turning blue in acidic soil (pH 5) and pink in neutral to basic soil (pH 7).
Critically Think:
Consider the proximate and ultimate causes of animal behaviors and how they relate to survival. For example, raven calls during feeding compared to investment in food defense can be explored.