Testing hypothesis Flashcards
Fitness Trade-offs
• Trade-off occurs when a behavior benefits an organism in
one aspect of fitness, imposes a cost in another.
• Trade-offs exist within or between some behaviors or
activities (due to limited resources, energy, time, etc.)
• Ex. Foraging vs. avoiding predators
• Ex. Reproducing now vs. in the future
• Trade-offs limit the types of behaviors that an organism
exhibits or that a species evolves
Experiments
(good for asking questions about how a
behavior has/could evolve within a species)
Ex. examining fitness consequences of social vs. asocial
behavior within a species.
Ex. measuring costs/ benefits of a behavior within a species
Comparative methods
(good for asking questions
about evolutionary origins of traits, longer evolutionary
time-scale)
Ex. comparing fixed differences in social behavior btw
species
Old school comparative approach
• Researchers formed hypotheses about why species had
certain traits (ex. due to predation, competition, etc.).
• Examined species with different versions of trait, asked if
ecological differences btw species matched predictions.
Limitations of Comparative Approach
Alternative hypotheses often not considered in
rigorous manner
Gives correlations rather than cause-effect, e.g.,
1. Seed eating may select for flocking, or
2. Predation may select for flocking, and flocks are
forced to eat locally abundant food (seeds)
Treats species as independent data points
(in reality, some species closer relatives than
others)
Speciation
the evolution of two or more distinct species
from one ancestral species
Phylogeny:
pattern of relatedness among taxa
(populations, species, etc.); depicted using a
phylogenetic tree
Branch
(population or lineage
through time)
Node
(most recent common
ancestor)
Transition
(appearance of
new trait—due to mutations)
