Analysis of a meristic trait for hybridization in sunfishes (genus Lepomis)

Abstract

SummaryNecessity of a thorought study of hybridization, following the breakdown of reproductive isolating mechanisms between naturally occurring populations, has been felt by biologists in geneeral and ichthyologists in particular. In this connection a formula for ‘hybrid index’ developed mainly by Hubbs & Kuronuma (1942) and Hubbs, Hubbs & Johnson (1943) has widely been in use, to test the assumption of hybridity and to study the mode of inheritance. Misra, Bateson & Keenleyside (1970) gave statistical methods of analysing hybrid indices estimated for characters of the ‘continuous’ type, and also provided a numerical example. Recently Misra (1971) gave a method of doing similar analysis for hybrid indices estimated for meristic characters, but no example was provided, as data were not available to him. This paper presents a study of hybridization in the sunfishes (genus Lepomis) of Pinehurst Lake, Ontario, Canada, based on the number of scales below the lateral line; the primary purpose of the study is to show the complete computational procedure involved in the application of the method of Misra (1971), so that those users of the method who are mainly interested in the applied aspects of the method, can bypass the mathematics easily.