Proximate explanation
Ultimate explanation
-require evolutionary reasoning and analysis
Tinbergen’s Four Questions - Proximate
Tinbergen’s Four Questions - Ultimate
Example for ultimate and proximate explanation - Crested owls hunt at night and can capture their pray in total darkness
Proximate questions
Ultimate questions:
Female chimpanzee experiment set up
Research Question: Do pregnant and lactating chimpanzees (Pan troglodytes) alter their feeding behaviour to compensate for increased energy demands of reproduction?
Hypothesis: Pregnant and lactating females will consume a diet that provides higher caloric intake than will non pregnant, non lactating females
Prediction: Pregnant and lactating females will have a higher caloric diet (of fruit) than non lactating or pregnant females
Methods: the adults were classified into 3 categories
The feeding behaviours were recorded
Foraging = looking for food, eating
Travelling = did they have to travel to find food
–> once they reached the area where there is food, it is not considered travelling, it is now foraging
Female Chimp experiment results and conclusion
REFER TO GRAPHS
The pregnant chimps do not go as far or forage as long. This being said, the pregnant and lactating chimps have more calories in their diet.
The pregnant and lactating chimps don’t spend as much time looking at different food sources, their target is very specific to fruits which are high energy
Conclusion: Female chimpanzees appear to alter their diet to include more high calorie fruit when pregnant and lactating to increase their caloric intake
Challenges when studying animals
Reactivity: minimize the reactivity to humans. Animals should not be reacting to humans. Humans should be far enough away to not be seen.
External validity: to maximize validity, what you are observing in the sample population should generalize to the entire population. For this to occur you have to decrease your presence as you being their could affect the way the sample group behaves and therefore this would not be generalizable to the entire population.
Tropical Tadpole experiment set up
REFER TO GRAPHS
Research questions: Why do tadpoles jump out of puddles?
Hypothesis: Jumping is an antipredator behaviour
Prediction: Tadpoles will jump most often from puddles that contain predators
IF jumping is an antipredator response THEN the tadpoles will jump most often from the puddle that contains predators
Methods:
Tadpole experiment 1
Tadpoles were placed in 1 of 3 treatments
Number of jumps per tadpole were recorded
Results: jumps were most common in the predator arena
Tadpole experiment 2
Tadpoles were placed in one of 2 treatments:
Results: Survival was highest in the non screened arena
Tadpole experiment conclusion
Tadpole jumping behaviour is an effective antipredator behaviour that enhances survivorship
Ancestral Traits
Plesiomorphic
Found in common ancestors or two or more species
Derived traits
Apomorphic
Found in more recently evolved species and not present in common ancestor
Phylogeny
Diagram showing evolutionary ancestor descendent relationships among a set of organisms
Use genetics and any variable we are interested in examining
Sister Species
Two species that are more closely related to one another than to any other species
They are more genetically similar than other species in that genus
Order of Phylogeny
Life Domain Kingdom Phylum Class Order Family Genus Species
Mice Phylogeny
Genus: Peromyscus Species: -californicus -polionotus -eremicus -leucopus -crinitus
Burrowing mice experiment set up
REFER TO GRAPHS
Research question: How did burrowing behaviour evolve in different species of Peromyscus mice?
Methods: Construct a phylogeny of 7 species using genetic data
Characterize the burrowing behaviour of each species (no burrow construction, simple burrows, complex burrows)
Map the burrow behaviour onto the phylogeny –> wanted to map the behaviours on top of the genes of the phylogeny
Compare burrowing of closely related species
Results from mice burrowing
The graph has 2 values on the x axis
The y axis shows the respective species
There is a lot of variation between the frequency and complexity of the burrows between species
Results:
Conclusion:
-burrowing behaviours appear to have evolved independently across species are are therefore derived traits.
The common ancestral trait is the absence of burrows
–> this is the assumption because of the extreme variation
The Three R’s
Replacement:
Is there a way to create a simulation and get the same data
Encourages use of computer modeling, videotapes, or other approaches in place of actual research animals in the laboratory
Reduction:
Promotes limiting the number of animals subject to disturbance in research or teaching
Refinement:
Involves improving procedures and techniques to minimize pain and stress for animals
Charles Darwin
Comparative biology
Looking at differences and similarities between species
C. Loyd Morgan
He criticized Romanes’ approaches Says that interpretations, and research design need to be simple, no need to put together such an complex research question and hypothesis
Simplicity is very important in science
Avoid anecdotal evidence –> evidence from personal experience