Many populations have intraspecific diversity in phenotype and ecological strategy, but the mechanisms maintaining such diversity are not fully understood. Multiple behaviors can be maintained either as a conditional strategy, where fitness depends on an individual’s phenotype, or as a mixed strategy where alternative behaviors have similar fitness independent of phenotype. Using high-resolution depth and time sampling, we characterize two distinct diel vertical migration behaviors in a population of freshwater zooplankton (Daphnia pulicaria). Individuals in this population differ in their color phenotype and migratory behavior with red morphs upregulating hemoglobin and undergoing a deep migration, and pale morphs not producing hemoglobin and undergoing a shallow migration. We experimentally manipulated the behavior of each phenotype in the field, and measured population growth in their natural migration behavior as well as population growth in their alternative behaviors. Experimental populations of pale and red morphs under their natural migrations had roughly equal fitness, despite vast differences in environmental conditions. When forced to switch behaviors, pale morphs suffered reduced fitness, whereas red morphs had similar fitness compared to their natural migration. Our results suggest that while behavioral diversity may be promoted by the opportunity for alternative behaviors of equal fitness, the distinct physiological conditions required for survival in alternative behaviors limit the capacity for individual behavioral switching and likely maintain behavioral diversity as a conditional strategy.
3AM Size by Depth counts with colour morph
Rep: Replicate number; levels: 1,2
Depth: Depth of Daphnia sampling in Round Lake
Size: Individual Daphnia size class; levels 1-5, where 1: <1.0mm; 2: 1.0-1.4mm; 3: 1.4-1.85mm; 4: 1.85-2.3mm; 5 >2.3mm
Morph: Colour morph; levels: “Pale”, “Red”
Freq: Number of Daphnia
Daphnia colour from 24h lake sampling
This file pertains to Figure 1a.
Rep: Replicate number; levels: 1,2
Date: Sampling date
Time: Time of day on 24-hour schedule
Depth: Depth of Daphnia sampling in Round Lake
Red: Amount of red colour from 0-255
Green: Amount of green colour from 0-255
Blue: Amount of blue colour from 0-255
Redness: Distance from pure red (255, 0, 0), calculated with the following: sqrt((255-Red)^2+(0-Green)^2+(0-Blue)^2).
Daphnia Colour from Migration Experiments
This file pertains to Figure 1b.
Rep: Replicate number; levels: 1,2
Tube: Migration tube number; levels: 1-40
Migration: Migration schedule; levels: “Shallow”, “Deep”
Sample Depth: Depth at which individual Daphnia were sampled from prior to beginning experiment; levels: “Epilimnion” (3-5 meters), “Hypolimnion” (15 meters)
Treatment: Combination of Hb state at the start of experiment and migration schedule; levels: “pales.shallow”, “reds.deep”, “pales.deep”, “reds.shallow”
Date: Census date (all 2014)
Experiment Day: Days since start of experiment; levels: 0-14
Red: Amount of red colour from 0-255
Green: Amount of green colour from 0-255
Blue: Amount of blue colour from 0-255
Redness: Distance from pure red (255, 0, 0), calculated with the following: sqrt((255-Red)^2+(0-Green)^2+(0-Blue)^2).
Environmental Conditions (temp, oxygen, chla) Summer 2014
This file pertains to Figure 2.
Depth: Depth of measurement in Round Lake, Ontario
Temperature.C: Temperature in degrees Celsius
Oxygen.mg.L: Oxygen concentration in milligrams per liter
Chl.a: Chlorophyll a concentration in micrograms per liter
Mean Redness per Tube
This figure pertains to Figure 5 and is a summary table derived from Daphnia Colour from Migration Experiments.
Tube: Migration tube number; levels: 1-40
Day: Days since start of experiment; levels: 0-14
Treatment: Combination of Hb state at the start of experiment and migration schedule; levels: “pales.shallow”, “reds.deep”, “pales.deep”, “reds.shallow”
Mean Redness: Mean distance from pure red for each tube
Mean_Depth
This file pertains to Figure 2 and is a summary table derived from MigrationDynamics.
Rep: Replicate number; levels: 1,2
Time: Time of day on 24 hour schedule
Phenotype: Colour morph; levels: “Pale”, “Red”
Mean Depth: Mean depth of individual Daphnia at sampling time
Median Depth: Median depth of individual Daphnia at sampling time
Migration_Experiment_Size_Eggs
This file pertains to Figure 4 and Figure 5.
Rep: Replicate number; levels: 1,2
Tube: Migration tube number; levels: 1-40
Size Class: Individual Daphnia size class; levels 1-5, where 1: <1.0mm; 2: 1.0-1.4mm; 3: 1.4-1.85mm; 4: 1.85-2.3mm; 5 >2.3mm
Number of Eggs: Number of eggs in the brood pouch of each Daphnia
Migration: Migration schedule; levels: “Shallow”, “Deep”, “Weird” (Weird was a designation given to one tube which, due to sensor problems, did not follow the intended migration schedule. This tube was ultimately excluded from the analysis).
Sample Depth: Depth at which individual Daphnia were sampled from prior to beginning experiment; levels: “Epi” (3-5 meters), “Hypo” (15 meters)
Date: Census date (all 2014)
Experiment Day: Days since start of experiment; levels: 0-14
Size.mm: Estimated size of each Daphnia in millimeters (taken as the average of each size class)
Treatment: Combination of Hb state at the start of experiment and migration schedule; levels: “pales.shallow”, “reds.deep”, “pales.deep”, “reds.shallow”, “weird” (“weird” was a designation given to one tube which, due to sensor problems, did not follow the intended migration schedule. This tube was ultimately excluded from the analysis)
MigrationDynamics
This file pertains to Figure 1c.
Rep: Replicate number; levels: 1,2
Depth: Depth of Daphnia sampling in Round Lake
Morph: Colour morph; levels: “Pale”, “Red”
Time: Time of day on 24-hour schedule
Count: Number of Daphnia
Proportion: # animals sampled at depth X, time Y/total animals sampled over time Y
Percent: (# animals sampled at depth X, time Y/total animals sampled over time Y) * 100