QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

This Article Summary Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Jokela, M. Articles by Donner, K. Search for Related Content PubMed PubMed Citation Articles by Jokela, M. Articles by Donner, K.

Polymorphism of the rod visual pigment between allopatric populations of the sand goby (Pomatoschistus minutus): a microspectrophotometric study

Mirka Jokela^1,*, Annika Vartio¹, Lars Paulin², Nanna Fyhrquist-Vanni¹ and Kristian Donner¹

¹ Department of Biosciences, University of Helsinki, PO Box 65 (Viikinkaari 1), FIN-00014, Finland
² Institute of Biotechnology, University of Helsinki, PO Box 65 (Viikinkaari 1), FIN-00014, Finland

View larger version (27K): [in a new window]   Fig. 1. Geographical locations and spectral light environments (A), individual rod absorbance spectra (B) and distributions of rod max values (C) of sand gobies from the four populations studied. (A) The four locations from which gobies were collected. The wavelength range connected with each site gives the approximate band of maximum transmission of the respective water according to Jerlov (1976). The colour code used here and in all other figures is: red and violet, Tvärminne Zoological Station, Finland (sand gobies and common gobies, respectively, denoted B for `Baltic'); yellow, Kristineberg Marine Research Station, Sweden (sand gobies, denoted S for `Swedish'); orange, University of Plymouth, England (sand gobies, denoted E for `English'); blue and green, Chioggia Marine Biological Station, Italy (sand gobies and marbled gobies, respectively, denoted A for `Adriatic'). (B) Examples of rod absorbance spectra from individual sand gobies. Colour code as in A. The max values of these individuals are 508.6 nm (B), 505.7 nm (S), 505.7 nm (E) and 501.9 nm (A). The spectra shown here and in subsequent figures have been Fourier-filtered, with 25 harmonics retained. (C) Distribution of the max values in all 54 sand gobies on 1-nm bins. The different populations are distinguished by colour as in A and B: red (N=17), orange (N=10), yellow (N=9) and blue (N=18).

View larger version (19K): [in a new window]   Fig. 2. Sand goby spectra indicate no measurable proportion of A2 chromophore. (A) The absorbance spectrum of a Baltic sand goby (same as in Fig. 1B; red dotted line) fitted with two Govardovskii et al. (2000) templates, one for pure A1 and one for a 95%:5% mixture of A1 and A2 (continuous black lines). The two templates are virtually indistinguishable over most of the main absorption band, but in the long-wavelength domain (enlarged in the Inset) the A1:A2 mixture provides a poor fit to the data. (B) Testing the hypothesis that the Baltic spectrum could arise from using some proportion of A2 chromophore with the Adriatic opsin. The blue and red dotted curves are the Adriatic and Baltic spectra from Fig. 1B (max=501.9 nm and 508.6 nm, respectively). The former has been fitted with a pure A1 (501.9 nm) template. Then, the assumed percentage of its A2 pigment pair in a mixture has been increased until max has moved to 508.6 nm. This required 39% A2. The continuous black curve shows the full template curve for a 61%:39% mixture, which clearly does not fit the long-wavelength limb of the Baltic spectrum.

View larger version (16K): [in a new window]   Fig. 3. Comparison with the rod absorbance spectra of common goby and marbled goby. (A) Individual spectra of common goby from the Baltic Sea (violet) and marbled goby from the Gulf of Venice (green). The Adriatic sand goby spectrum from Fig. 2 is reproduced as a reference (blue). (B) Distribution of the max values measured in 10 common gobies and two marbled gobies on 1-nm bins. For comparison, the max ranges spanned by the four populations of sand gobies are shown as bars above the histogram. Colour code as in Fig. 1.

View larger version (15K): [in a new window]   Fig. 4. Calculated spectral quantum catch for rods of Baltic common gobies (violet curve), Baltic sand gobies (red curve) and Adriatic sand gobies (blue curve) in Pojoviken Bay of the Baltic Sea (spectral distribution of light quanta measured at 10 m depth by Lindström, 2000; grey curve). The quantum catch spectra were obtained by convolution of the light spectrum with the respective rod absorbance spectra, all initially normalized to unity. The integrals of the quantum catch spectra give total quantum catches, which are related as 1 (blue), 1.19 (red) and 1.46 (violet).