ISSN:
1432-1432
Keywords:
Key words: Opsin — Phylogeny — Crayfish — Cambaridae — Vision — Wavelength — Maximum likelihood — Ancestral sequences
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract. This study examines the diverse maximum wavelength absorption (λmax) found in crayfishes (Decapoda: Cambaridae and Parastacidae) and the associated genetic variation in their opsin locus. We measured the wavelength absorption in the photoreceptors of six species that inhabit environments of different light intensities (i.e., burrows, streams, standing waters, and subterranean waters). Our results indicate that there is relatively little variation in λmax (522–530 nm) among species from different genera and families. The existing variation did not correlate with the habitat differences of the crayfishes studied. We simultaneously sequenced the rhodopsin gene to identify the amino acid replacements that affect shifts in maximum wavelength absorption. We then related these to changes that correlated with shifts in λmax by reconstructing ancestral character states using a maximum-likelihood approach. Using amino acid sequences obtained from five species (all were 301 amino acids in length), we identified a number of candidates for producing shifts of 4 to 8 nm in λmax. These amino acid replacements occurred in similar regions to those involved in spectral shifts in vertebrates.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/PL00006257
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