Molecular
genetic markers provide no evidence for
reproductive
isolation among retreat building phenotypes
of the net-spinning caddisfly Macrostemum Carolina
G.
R. PLAGUE,1,2 M. MULVEY,3 T. C. GLENN1
and J. V. McARTHUR1
1Savannah
River Ecology Laboratory, University of Georgia, PO Drawer E, Aiken, SC 29802,
USA, 2Department of Entomology, University of Georgia, Athens, USA, 3Virginia Institute of Marine Science, The College of William and
Mary, Gloucester Point, USA
Abstract
Larvae of the stream-dwelling, filter-feeding caddisfly
Macrostemum carolina construct
silken catchnets within protective retreats.In the Savannah River, M. carolina individuals
make three different retreats, each with a distinct
water entrance hole: (i) at the end of a
silken tube; (ii) with a ~180° silken backstop; and
(iii) flush with the top of the retreat.
To resolve whether these different retreats represent
alternative behavioural phenotypes
within a single panmictic population or fixed
phenotypes within three genetically distinct populations or species, we compared the allele
frequencies at three polymorphic
nuclear loci (allozyme electrophoresis for Gpi, Mpi and Pgm) and
the mitochondrial DNA
(mtDNA) haplotype frequencies among individuals displaying the three retreat
morphs.We also calculated pairwise exact tests of population
differentiation using the allozyme
and mtDNA allele frequencies.No significant genetic differentiation was detected among
caddisflies exhibiting the different retreat morphs.Therefore, these morphs apparently
represent a single panmictic population in the Savannah
River.Consequently, additional
study is required to assess whether this retreat polymorphism is a
phenotypically plastic
trait under conditional control, or is mediated by alternative alleles at a
Mendelian gene
or genes (or a combination of the two).
Plague, G. R., M. Mulvey, T. C.
Glenn, and J. V. McArthur. 2001. Molecular genetic markers provide no evidence
for reproductive isolation among retreat building phenotypes of the net-spinning
caddishfly Macrostemum carolina. Molecular Ecology 10:243-248.
