Week 1: 02 Behavior Flashcards
House finch
A moderately-sized finch
Found in North America
Males are more brightly coloured than females
Male coloration varies in intensity with the seasons
The colours range from pale yellow through bright orange to intense red.
Dr. Geof Hill
Professor & Curator of Birds
Auburn University
Geoff leads an integrative research program investigating the function and evolution of animal ornamentation.
The Hill group addressed the nature of differential plumage coloration in male and female house finches.
Cartotenoids
Lipophilic biochemical
reflected colours: yellow, orange, red and pink
Animals lack the ability to synthesise carotenoids from precursors
they must obtain them from their diet
In males,
Cartenoid-rich diet leads to….
Cartenoid-poor diet leads to….
Males with bright coloration
Males with drab coloration
Hill’s work demonstrated that at the proximate level, differences in male plumage were correlated with the amount of carotenoids in their diet.
In females
Cartenoid-rich diet leads to….
Cartenoid-poor diet leads to….
Females with brighter plumage
Females with drab plumage
- Females in the carotenoids treatment developed much brighter plumage.
- There is between-population differences in female plumage coloration.
- The more such food is present in the environment, the brighter the average females is in a population.
Females vs Males in regards to diet.
Males actively search for and ingest catenoid-based foods, where females eat carotenoid-based foods, but they don’t actively search for such food.
So the sexual differences in plumage coloration does not result from the availability of cartenoid-based foods.
Rather, the differences in foraging strategies explain the sexual differences in plumage coloration at the proximate level.
Ultimate questions for differences in plumage coloration
Why do males, but not females, actively search for carotenoid-based foods?
Hill hypothesized that males receive significant benefits for having colorful plumage, but females do not.
But what exactly were these benefits?
Plumage manipulation experiments
Males that had their color experimentally brightened were much more likely to get a mate than males whose color had been experimentally lightened.
–>
Bright males are more attractive to females than drab males.
Ultimate question: Are there benefits for females that choose males with brighter plumage coloration?
Plumage is an indicator of male quality
Brighter males are good fathers with respect to feeding young
Brighter males are good foragers and produce sons that are good foragers.
Pathogen inoculation experiments
Males with more elaborate plumage coloration were able to rid themselves of the pathogen more quickly than drab-colored males.
Colorful males that had been selected as mates had lower levels of bacteria that degrade the quality of feathers.
Male feeding statistic
The mean number of times a male fed a chick at his nest was positively correlated with the intensity of his plumage coloration.
Brighter males fed chicks more than twice as often as drabber males.
Plumage coloration inherited or acquired?
Coloration can’t be inherited, its diet dependent.
Proximate perspectives/causes
“how” or “what”
related to the immediate causation (stimulus and mechanism) for the behavior
address the genetic, physiological, and anatomical mechanisms underlying a behavioral act.
Ultimate perspectives/causes
“why”
related to the survival and reproductive success of the animal.
address the evolutionary significance of a behavior.
Levels of questions: proximate vs ultimate
Proximate questions:
- What causes the variation in male plumage in the house finch?
- What causes differences in plumage coloration between males and females?
Ultimate questions:
- Why do males, but not females, actively search for carotenoid-based foods?
- Why females prefer males with bright plumage?
Both levels of analysis are equally important
Proximate and ultimate explanations complement each other.
Tree of life
The evolutionary relationships in this figure is a hypothesis
rRNA genes
Animals, plants, and fungi are little twigs of the Eukarya branch.
Animals
Animals are multicellular, heterotrophic eukaryotes with tissues that develop from embryonic layers.
Animals: ingest and digest.
Fungi are heterotrophs: digest and ingest.
Plants are autotrophs.
Cell structure and specialisation in animals
Their bodies are held together by structural proteins such as collagen
Nervous tissue and muscle tissue are unique, defining characteristics of animals
–> movement
What is behavior?
Behavior is what an animal does and how it does it. (Niko Tinbergen 1963)
Behavior is the coordinated response of whole living organisms to internal and/or external stimuli. (Lee Alan Dugatkin 2004)
Example of what is and isn’t behavior
sweating in response to increasing body temperature→ no behavior
an animal moves to the shade in response to heat and its own sweating → behavior
Four major approaches to the study of animal behavior
Ethology
Behavioural ecology
Sociobiology
Comparative psychology
Ethology
The study of behavior of animals in their natural surroundings, with its focus on instinctive or innate behavior
Behavioral ecology
The study of the relationships between a species’ behavior and its environment.
Sociobiology
The study of the biological basis of social behavior. Of special interest is behavior that helps pass on the gene pool to the next generation.
Comparative psychology
The study of the mechanisms controlling behavior, learning, sensation, perception, and behavior genetics. Animal behavior has been studied for many decades by psychologists, physiologists, and cognitive scientists.
Pioneers in the study of animal behavior
Niko Tinbergen
Konrad Lorenz
Karl von Frisch
These ethologists won the Nobel Prize in Medicine in 1973 in recognition of their contributions to an understanding of the proximate causes of behavior.
Tinbergen’s four questions
The causes of any behavior can potentially be understood in terms of four different levels of analysis
- development: how the behavior develops
- causation: how physiological mechanisms work to make the behavior possible
- function: how the behavior promotes the animal’s reproductive success
- evolution: how the behavior originated and has been changed over evolutionary time.
