Geographic Variation in Morphology Among Wisconsin Populations of the Orangespotted Sunfish, Lepomis humilis
Mentor 1
Michael Pauers
Location
Union Wisconsin Room
Start Date
24-4-2015 2:30 PM
End Date
24-4-2015 3:45 PM
Description
The fishes of the Family Centrarchidae are common throughout North America, and many species are popular food and game fishes. Despite the general prevalence and popularity of the family, little is known about many of the non-game species, including the Orangespotted Sunfish (Lepomis humilis). As a first step towards increasing what is known about this species, we measured morphological and meristic traits among nine populations throughout its range in Wisconsin. Using specimens from the collections of the Milwaukee Public Museum, we measured sixteen distances between various structures or landmarks and counted six meristic characteristics on each specimen. We then subjected these data to two separate principal components analyses (PCA): a sheared PCA for the morphological data, which removed the effect of size from the measurements, leaving only shape; and a standard PCA on the meristic data. Among all populations, there is very little morphological divergence; indeed, all populations are virtually morphologically identical. Interestingly, one population, from Lake Belle View in Dane County, has significantly fewer, yet larger, pored lateral line scales. While the scales of the Lake Belle View population certainly warrant further investigation, especially because Lake Belle View is a manmade lake and has only existed for 102 years, our results also suggest that since such variation can occur over a relatively small geographical scale, an analysis of morphometric and meristic variation should be performed for populations of the Orangespotted Sunfish throughout its range.
Geographic Variation in Morphology Among Wisconsin Populations of the Orangespotted Sunfish, Lepomis humilis
Union Wisconsin Room
The fishes of the Family Centrarchidae are common throughout North America, and many species are popular food and game fishes. Despite the general prevalence and popularity of the family, little is known about many of the non-game species, including the Orangespotted Sunfish (Lepomis humilis). As a first step towards increasing what is known about this species, we measured morphological and meristic traits among nine populations throughout its range in Wisconsin. Using specimens from the collections of the Milwaukee Public Museum, we measured sixteen distances between various structures or landmarks and counted six meristic characteristics on each specimen. We then subjected these data to two separate principal components analyses (PCA): a sheared PCA for the morphological data, which removed the effect of size from the measurements, leaving only shape; and a standard PCA on the meristic data. Among all populations, there is very little morphological divergence; indeed, all populations are virtually morphologically identical. Interestingly, one population, from Lake Belle View in Dane County, has significantly fewer, yet larger, pored lateral line scales. While the scales of the Lake Belle View population certainly warrant further investigation, especially because Lake Belle View is a manmade lake and has only existed for 102 years, our results also suggest that since such variation can occur over a relatively small geographical scale, an analysis of morphometric and meristic variation should be performed for populations of the Orangespotted Sunfish throughout its range.
