Limits...
Individual variation in cone photoreceptor density in house sparrows: implications for between-individual differences in visual resolution and chromatic contrast.

Ensminger AL, Fernández-Juricic E - PLoS ONE (2014)

Bottom Line: We found consistent between-individual variation in the densities of all five types of avian cones, involved in chromatic and achromatic vision.Using perceptual modeling, we found that this degree of variation translated into significant between-individual differences in visual resolution and the chromatic contrast of a plumage signal that has been associated with mate choice and agonistic interactions.Overall, our findings (a) highlight the need to consider multiple individuals when characterizing sensory traits of a species, and (b) provide some mechanistic basis for between-individual variation in different behaviors (i.e., animal personalities) and for testing the predictions of several widely accepted hypotheses (e.g., honest signaling).

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, Purdue University, West Lafayette, Indiana, United States of America.

ABSTRACT
Between-individual variation has been documented in a wide variety of taxa, especially for behavioral characteristics; however, intra-population variation in sensory systems has not received similar attention in wild animals. We measured a key trait of the visual system, the density of retinal cone photoreceptors, in a wild population of house sparrows (Passer domesticus). We tested whether individuals differed from each other in cone densities given within-individual variation across the retina and across eyes. We further tested whether the existing variation could lead to individual differences in two aspects of perception: visual resolution and chromatic contrast. We found consistent between-individual variation in the densities of all five types of avian cones, involved in chromatic and achromatic vision. Using perceptual modeling, we found that this degree of variation translated into significant between-individual differences in visual resolution and the chromatic contrast of a plumage signal that has been associated with mate choice and agonistic interactions. However, there was no evidence for a relationship between individual visual resolution and chromatic contrast. The implication is that some birds may have the sensory potential to perform "better" in certain visual tasks, but not necessarily in both resolution and contrast simultaneously. Overall, our findings (a) highlight the need to consider multiple individuals when characterizing sensory traits of a species, and (b) provide some mechanistic basis for between-individual variation in different behaviors (i.e., animal personalities) and for testing the predictions of several widely accepted hypotheses (e.g., honest signaling).

Show MeSH

Related in: MedlinePlus

Between-individual variation in single cone type proportions out of the total density of cones (including double cones—not shown—which make up on average 37% of all cones).Each bar represents the mean and standard error for an individual—the errors represent within-individual variation across sites and eyes.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4221115&req=5

pone-0111854-g004: Between-individual variation in single cone type proportions out of the total density of cones (including double cones—not shown—which make up on average 37% of all cones).Each bar represents the mean and standard error for an individual—the errors represent within-individual variation across sites and eyes.

Mentions: We found strong evidence of consistent between-individual variation in cone type proportions, for double cones and for each type of single cone (Fig. 4, Table 3). Adjusted repeatabilities within each eye were highest for LWS single cones and the double cones (Table 3). All covariances between the eyes were substantial, with UVS cones having the lowest covariance correlation, and LWS having the highest (Table 3). These results suggest that individuals differ consistently from each other in the proportions of each cone type.


Individual variation in cone photoreceptor density in house sparrows: implications for between-individual differences in visual resolution and chromatic contrast.

Ensminger AL, Fernández-Juricic E - PLoS ONE (2014)

Between-individual variation in single cone type proportions out of the total density of cones (including double cones—not shown—which make up on average 37% of all cones).Each bar represents the mean and standard error for an individual—the errors represent within-individual variation across sites and eyes.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4221115&req=5

pone-0111854-g004: Between-individual variation in single cone type proportions out of the total density of cones (including double cones—not shown—which make up on average 37% of all cones).Each bar represents the mean and standard error for an individual—the errors represent within-individual variation across sites and eyes.
Mentions: We found strong evidence of consistent between-individual variation in cone type proportions, for double cones and for each type of single cone (Fig. 4, Table 3). Adjusted repeatabilities within each eye were highest for LWS single cones and the double cones (Table 3). All covariances between the eyes were substantial, with UVS cones having the lowest covariance correlation, and LWS having the highest (Table 3). These results suggest that individuals differ consistently from each other in the proportions of each cone type.

Bottom Line: We found consistent between-individual variation in the densities of all five types of avian cones, involved in chromatic and achromatic vision.Using perceptual modeling, we found that this degree of variation translated into significant between-individual differences in visual resolution and the chromatic contrast of a plumage signal that has been associated with mate choice and agonistic interactions.Overall, our findings (a) highlight the need to consider multiple individuals when characterizing sensory traits of a species, and (b) provide some mechanistic basis for between-individual variation in different behaviors (i.e., animal personalities) and for testing the predictions of several widely accepted hypotheses (e.g., honest signaling).

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, Purdue University, West Lafayette, Indiana, United States of America.

ABSTRACT
Between-individual variation has been documented in a wide variety of taxa, especially for behavioral characteristics; however, intra-population variation in sensory systems has not received similar attention in wild animals. We measured a key trait of the visual system, the density of retinal cone photoreceptors, in a wild population of house sparrows (Passer domesticus). We tested whether individuals differed from each other in cone densities given within-individual variation across the retina and across eyes. We further tested whether the existing variation could lead to individual differences in two aspects of perception: visual resolution and chromatic contrast. We found consistent between-individual variation in the densities of all five types of avian cones, involved in chromatic and achromatic vision. Using perceptual modeling, we found that this degree of variation translated into significant between-individual differences in visual resolution and the chromatic contrast of a plumage signal that has been associated with mate choice and agonistic interactions. However, there was no evidence for a relationship between individual visual resolution and chromatic contrast. The implication is that some birds may have the sensory potential to perform "better" in certain visual tasks, but not necessarily in both resolution and contrast simultaneously. Overall, our findings (a) highlight the need to consider multiple individuals when characterizing sensory traits of a species, and (b) provide some mechanistic basis for between-individual variation in different behaviors (i.e., animal personalities) and for testing the predictions of several widely accepted hypotheses (e.g., honest signaling).

Show MeSH
Related in: MedlinePlus