Bathyal octopods of the genus Graneledone Joubin, 1918 in the northeast Pacific differ dramatical... more Bathyal octopods of the genus Graneledone Joubin, 1918 in the northeast Pacific differ dramatically in skin texture. To test the hypothesis that these differences are associated with geography, we quantified the skin warts and tubercles of 50 specimens collected between 36°N and 46°N from 1116 to 2850 m depth. Using Principal Component Analysis (PCA), we analyzed the numbers of mantle and head warts, mantle and web tubercles, arm suckers, and inner and outer gill lamellae, adding head width as a size proxy. We used Canonical Correlation Analysis to explicitly test the relationship of morphology to depth and latitude. Sequences of 12S rRNA, 16S rRNA, and COI genes from twelve individuals quantified genetic divergence. PCA revealed correlated variation in head width, arm suckers, and gill lamella counts opposed by skin texture on PC1; PC2 showed correlated variation in skin texture opposed by gill lamella counts. Both components correlate with depth and latitude but, as most shallow specimens came from southern localities, the correlation with latitude may be artefactual. This relationship is corroborated by the canonical correlations. Octopods from greater depths are smaller than those from shallower depths, have rougher skin texture, and fewer suckers and gill lamellae. Clades of shallow and deep octopods show 0.8% genetic divergence in COI (Kimura two-parameter distance), not inconsistent with intraspecific differentiation. We conclude that the variation is likely clinal with depth. The observed morphological differences may result from differences in food availability and oxygen saturation with depth.
PRICE, T., M. KIRKPATRICK, AND S. J. ARNOLD. 1988. Directional selection and the evolution of bre... more PRICE, T., M. KIRKPATRICK, AND S. J. ARNOLD. 1988. Directional selection and the evolution of breeding date in birds. Science 240:798-799. READ, A. F., AND P. H. HARVEY. 1989. Life history differences among the eutherian radiations. J. Zool, 219:329-353. REID, W. V. 1987. The cost of reproduction in the glaucous-winged gull. Oecologia (Berlin) 74:458467. RICKLEFS, R. E. 1977. On the evolution ofreproductive strategies in birds: Reproductive effort. Am. Nat. 111:453-478. ROCKWELL, R. F., C. S. FINDLAY, ANDF. COOKE. 1987. Is there an optimal clutch size in Snow Geese? Am. Nat. 130:839-863. SCHAFFER, W. L. 1974. Optimal reproductive effort in fluctuating environments. Am. Nat. 108:783790. SMITH, J. N. M. 1981. Does high fecundity reduce survival in song sparrows? Evolution 35:1142-1148. SUTHERLAND, W. J., A. GRAFEN, AND P. H. HARVEY.
A set of cranial characters was examined in the fruit bats Rousettus egyptiacus and Eidolon helvu... more A set of cranial characters was examined in the fruit bats Rousettus egyptiacus and Eidolon helvum to compare trends and relative importance of major components of bilateral morphometric variation, and their relationship with character size. Using two‐way, sides‐by‐individuals ANOVA, four components of variation were estimated for each bilateral variable: individual variation (I), directional asymmetry (DA), non‐directional asymmetry (NDA) and measurement error (E). Both species exhibit similar major trends of variation in asymmetry across characters, as shown by principal component analysis, using variance components as variables. Degree of interspecific congruence among characters was confirmed by a two‐way ANOVA with species and variance components as fixed factors. Congruence of asymmetry patterns between species suggests that the concept of population asymmetry parameter (PAP) could be extended to higher hierarchies. PAPs above the species level may result from common mechanisms or similar developmental constraints acting on species’ buffering capacities and morphological integration processes.
Bathyal octopods of the genus Graneledone Joubin, 1918 in the northeast Pacific differ dramatical... more Bathyal octopods of the genus Graneledone Joubin, 1918 in the northeast Pacific differ dramatically in skin texture. To test the hypothesis that these differences are associated with geography, we quantified the skin warts and tubercles of 50 specimens collected between 36°N and 46°N from 1116 to 2850 m depth. Using Principal Component Analysis (PCA), we analyzed the numbers of mantle and head warts, mantle and web tubercles, arm suckers, and inner and outer gill lamellae, adding head width as a size proxy. We used Canonical Correlation Analysis to explicitly test the relationship of morphology to depth and latitude. Sequences of 12S rRNA, 16S rRNA, and COI genes from twelve individuals quantified genetic divergence. PCA revealed correlated variation in head width, arm suckers, and gill lamella counts opposed by skin texture on PC1; PC2 showed correlated variation in skin texture opposed by gill lamella counts. Both components correlate with depth and latitude but, as most shallow specimens came from southern localities, the correlation with latitude may be artefactual. This relationship is corroborated by the canonical correlations. Octopods from greater depths are smaller than those from shallower depths, have rougher skin texture, and fewer suckers and gill lamellae. Clades of shallow and deep octopods show 0.8% genetic divergence in COI (Kimura two-parameter distance), not inconsistent with intraspecific differentiation. We conclude that the variation is likely clinal with depth. The observed morphological differences may result from differences in food availability and oxygen saturation with depth.
PRICE, T., M. KIRKPATRICK, AND S. J. ARNOLD. 1988. Directional selection and the evolution of bre... more PRICE, T., M. KIRKPATRICK, AND S. J. ARNOLD. 1988. Directional selection and the evolution of breeding date in birds. Science 240:798-799. READ, A. F., AND P. H. HARVEY. 1989. Life history differences among the eutherian radiations. J. Zool, 219:329-353. REID, W. V. 1987. The cost of reproduction in the glaucous-winged gull. Oecologia (Berlin) 74:458467. RICKLEFS, R. E. 1977. On the evolution ofreproductive strategies in birds: Reproductive effort. Am. Nat. 111:453-478. ROCKWELL, R. F., C. S. FINDLAY, ANDF. COOKE. 1987. Is there an optimal clutch size in Snow Geese? Am. Nat. 130:839-863. SCHAFFER, W. L. 1974. Optimal reproductive effort in fluctuating environments. Am. Nat. 108:783790. SMITH, J. N. M. 1981. Does high fecundity reduce survival in song sparrows? Evolution 35:1142-1148. SUTHERLAND, W. J., A. GRAFEN, AND P. H. HARVEY.
A set of cranial characters was examined in the fruit bats Rousettus egyptiacus and Eidolon helvu... more A set of cranial characters was examined in the fruit bats Rousettus egyptiacus and Eidolon helvum to compare trends and relative importance of major components of bilateral morphometric variation, and their relationship with character size. Using two‐way, sides‐by‐individuals ANOVA, four components of variation were estimated for each bilateral variable: individual variation (I), directional asymmetry (DA), non‐directional asymmetry (NDA) and measurement error (E). Both species exhibit similar major trends of variation in asymmetry across characters, as shown by principal component analysis, using variance components as variables. Degree of interspecific congruence among characters was confirmed by a two‐way ANOVA with species and variance components as fixed factors. Congruence of asymmetry patterns between species suggests that the concept of population asymmetry parameter (PAP) could be extended to higher hierarchies. PAPs above the species level may result from common mechanisms or similar developmental constraints acting on species’ buffering capacities and morphological integration processes.
Uploads