BIOL 2040 Lecture Notes - Lecture 13: Tarantula Hawk, Natural Selection 2, Impala
3 May 2018
School
Department
Course
Professor
Studying Adaptations
November 5 & 10, 2015
Definition:
• An adaptation is a feature that evolved because it enhances fitness
• Adaptations evolve because alleles encoding them outreproduce the alternative alleles
Problem:
• Explanation is often too easy or simplistic
Camouflage and Mimicry
• Robber flies:
o Bee mimic/wasp mimic
o Tarantula hawk wasp
• Blend into environment for survival
General (Obvious?) Adaptations:
• Polar bears are white for camouflage
• Species with red flowers attract hummingbirds
• Don’t mate with relatives due to inbreeding depression
• Butterfly winds have marking for camouflage
• Giraffes have long necks for feeding
Main Methods for Studying Adaptation:
1. Measure Selection
• Which traits are positively correlated with fitness
• Only current natural selection
2. Experiment
• Control many variables
3. Prediction: what is optimal
• Often a mathematical model
• E.g. leaf shape in particular area
4. Comparative Model
• Many taxa or populations
Butterfly Wing Pattern:
• Predictions:
o Experimentally altered (opaque paint instead of clear) butterflies should suffer higher
bird predation and therefore should have:
▪ Shorter lives
▪ Greater wing damage
• Mark-recapture results: longetivity
o Experimental and control organisms had the same longetivity and wing damage
o Therefore, wing pattern has no effect on predation on birds
• Wings are not antipredatory
PART II
Red-Billed Oxpeckers (birds on impala or ox)
• Methods:
o Zimbabwe
o 2 Treatment groups: with and without oxpeckers
o Half cattle in each group – 1st
o Switched cattle – 2nd
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Definition: an adaptation is a feature that evolved because it enhances fitness, adaptations evolve because alleles encoding them outreproduce the alternative alleles. Problem: explanation is often too easy or simplistic. Camouflage and mimicry: robber flies, bee mimic/wasp mimic, tarantula hawk wasp, blend into environment for survival. Adaptations: polar bears are white for camouflage. Species with red flowers attract hummingbirds: don"t mate with relatives due to inbreeding depression, butterfly winds have marking for camouflage, giraffes have long necks for feeding. Butterfly wing pattern: predictions, experimentally altered (opaque paint instead of clear) butterflies should suffer higher bird predation and therefore should have: Shorter lives: greater wing damage, mark-recapture results: longetivity, experimental and control organisms had the same longetivity and wing damage, therefore, wing pattern has no effect on predation on birds, wings are not antipredatory. Increases with oxpeckers: decreases with no oxpecker, random, decreases with oxpeckers.
