2/4/2021: Isopod genetics proof of concept; “Lava” orange composition

by Kyle Kandilian · February 4, 2021

This Thursday it’s been nose to the isopod bins as the end is in sight; a mere 50 project tubs await me and it’s down to the nitty gritty of picking as few as a pair of some projects to continue on.

Today’s top discovery (so far) has been a proof of concept. In Porcellio scaber “Lava” (a STRAIN that needed to be labeled with locality data, NOT a morph), there are a few orange phenotypes with some nearing full body orange coloration. Logic suggests that with some high expression dark pigment individuals and the orangest individuals with varying scrap specks of dark pigment, the latter individuals would be due to a multi-gene orange. But what would happen if you took a true-breeding simple recessive orange line and crossed it into these? A few months ago I did just that.

The results are as I had hoped and expected: the first generation of the cross between the “US Orange” line (the originator of pure “Orange Dalmatian”, which was NOT created from crossing “Spanish Orange” to “Dalmatian”) and a male low dark pigment expression “Lava” produced mostly medium pigment expression individuals with dark eyes, which is typical for F1s of “Lava” crosses to wild type US scaber lines. A minority of low dark pigment expression individuals were produced but all had dark eyes and gray antennae tips indicating they were not expressing the simple recessive orange mutation (which produces orange or, at their darkest, red-brown eyes and pure orange antennae). I would expect the F2 to produce 1/4 simple recessive oranges and 3/4 medium to low dark pigmented individuals and will be testing for this.

But how can this be used to create new scaber lines? Well, of utmost interest is what a low expression, full-body orange “Lava” will look like when it’s also expressing simple recessive orange. Will the color be brighter? Will the orange disappear? I’m excited to see what will be created when crossing the two lowest dark pigment expression F1s. Likewise, what about the medium expression individuals? Will they have a reverse gradient of color, with white or light cream at the back and orange at the front still? We’ll see in a few months!

Most of the F1s. The two orange individuals both have dark antennae and, if you look closely at the posterior, dark pigment flecks/blotches. Higher quality images available on request for skeptics!

The next isopod compendium should be up in a few days. Stay posted!

-Kyle