- Email: [email protected]
Reply to Russell Graham about Mustela macrodon
Quaternary Research 56, 422–423 (2001) doi:10.1006/qres.2001.2268, available online at http://www.idealibrary.com on
REPLY Reply to Russell Graham about Mustela macrodon One wonderful thing about science is the ability to have a difference of opinion and a variation in how one views data. In 2000 we provided an article about the description of the skeleton of the extinct sea mink, Mustela macrodon (Mead et al., 2000). We used subfossil specimens from a number of archaeological localities (from the Gulf of Maine), but in particular we used the large sample from the Turner Farm site on North Haven Island. We compared these remains of archaic age to modern skeleltons of living taxa; we wanted to find the smallest and the largest forms (subspecies) found today within the living mink, Mustela vison. Besides describing the remains from the island and some mainland coastal localities, we wanted to discuss whether the extinct sea mink should or could be a distinct form of Mustela (hence it own species designation M. macrodon; original description) or if it is just a form of extirpated living mink carrying only a subspecies rank (M. vison macrodon). We presented both hypotheses and preferred the distinct species rank instead of the subspecies designation. Graham (2001) has indicated that, “[T]he sea mink is not a valid species but should be considered a subspecies.” The discussion is dialogue about what signifies sufficient “differences” to permit a species versus subspecies designation. Whether one prefers a species rank for the sea mink or a subspecies rank of the living mink is somewhat moot; it is obvious that the living forms of mink and the extinct sea mink are very closely related. We are not making light of Graham’s view or comments, but we are not sure what the precise distinction of rank means in the case of this animal and these remains at this time. Graham (2001) pointed out that in multiple cases our graphs of the sea mink (Mead et al., 2000, Figs. 7–13) overlap with the distributions of measurements of the living subspecies. We interpreted that the larger-than-today measurements were sea mink and that those remains found to be sometimes within the range of measurements of living mink subspecies not to be of the sea mink. Graham would like to have all of our measurements to be from the sea mink (the larger representing the male, the smaller representing the female) and therefore correspond to a general continuum or clinal set of measurements—all indicating that the sea mink is merely a larger form/subspecies of living mink. This is certainly a logical, albeit narrow, view of our data— one that we were engaged with for some time before publication. However, we felt, and still feel, that there is more to the data that might imply that the sea mink is distinct from other minks. Our intent was not to create the “final say” about the sea mink, but to 0033-5894/01 $35.00 C 2001 by the University of Washington. Copyright ° All rights of reproduction in any form reserved.
bring more data to all readers to promote more discussion about this poorly known animal. We showed that when the length of the palate is compared with the width between left and right M1s (first upper molars), the single sea mink specimen available for this comparison was distinctly larger than any living form (Mead et al., 2000, Fig. 6). Certain comparisons of measurements are better than others to show the distinction of sea mink versus all other living forms of mink. There is no question that with some of the distributions of measurements, the size of the sea mink seems to blend from the largest of living forms into the high end of the cline of measurements. In other cases a cluster of measurements from the sea mink seem to be well separated from the clinal measurements obtained from the living mink forms (e.g., Mead et al., 2000, Fig. 9 [with the length and width of the m1] and Fig. 11 [the greatest length and least diameter of the radius]. Having a suite of measurements from distinct taxa that overlap in the range of measurements does not dictate that the animals must all be grouped into a single species, as Graham would imply. For instance, if one plots the length and width of the m1 (lower first molar) from well-defined species of weasels (M. nivalis [short-tailed weasel], M. erminea [ermine], and M. frenata [long-tailed weasel]), one finds that their distributions of measurements overlap yet produce a continual cline of distribution. The same thing happens when using the ranges of length from the c1-m2 and p1-m2, the length and width of the m2, and the depth and width of the mandible. The same overlap of measurements happens within these weasels with the upper dentition. According to Elaine Anderson (a recognized authority on the osteology of mustelids; personal communication, March 2001), there really is no solid osteological distinction at the species level for these weasels except when a particular measurement fits into the non-overlap zone in the clinal distribution of all measurements. Our osteological data of the sea mink would seem to mirror her conclusions. We feel that the sea mink is typically larger than all living forms of the mink; sometimes the size is at the large end of a clinal distribution and sometimes it is distinctly and significantly larger (see Mead et al., 2000, Fig. 14). We found a few qualitative characters that also seem to show some distinction between the sea mink and all living forms of M. vison (Mead et al., 2000, p. 258). We discussed that the sea mink is certainly closely related to the living form and that it even belongs to the same subgenus Vison (versus Lutreola for the European mink).
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Like Graham, we too feel that diet was the function that permitted the predominantly island-living sea mink to become distinctly larger than the inland mainland form. Without additional data (e.g., carbon isotope data) it is purely speculation as to the makeup of the diet, although we would tend to agree with Graham’s statments. It appears to us that the critical difference is not so much a mainland versus island habitat, but more of a freshwater-habitat diet versus nutrient-rich marine-habitat diet. The sea mink is found mainly on the islands and along select mainland marine coastlines where the nutrient-rich, marine habitat occurs. The rectangular depression of the Gulf of Maine, of roughly 90,700 km2 , is extremely enriched in nutrients due to the vertical and horizontal mixing of fresh and oceanic waters (Apollonio, 1979). Certain coastal ecological systems are rich in nutrients, especially those of high-energy stresses. Coastal Maine in the region containing the many offshore islands (with the sea mink remains) has nutrient diverse systems, including rocky sea fronts, high-velocity channels, tide pools, kelp beds, neutral embayments and coastal plankton, and intertidal rocky areas (Odum and Copeland, 1974). It is well known that the islands of the Alexander Archipelago (southeast Alaska and British Columbia) have an extremely high-nutrient habitat in the littoral zone (see various chapters in Odum et al., 1974). The largest of all living mink, M. vison nesolestes (see discussion in Mead et al., 2000), certainly are able to attain their great size because of the littoral marine environment in which they inhabit. For this same reason other forms of mustelids and bears (Ursus) on these islands are also some of the largest or are the largest forms for their respective species. As we indicated, island forms of Mustela vison nesolestes are larger than the nearby mainland forms of M. v. eregumenos. We would state that not only are the marine-diet sea mink larger than freshwater-diet mainland forms, but they are also larger than any mainland forms anywhere in the present distribution of M. vison, and larger than any similar island forms of M. vison anywhere in the present distribution. The present marine-diet habitat islands in southeastern Alaska still have not produced a mink as large in many aspects of the skeleton as the sea mink of Maine (Mead et al., 2000, Fig. 14). Our point here is not to conclude that because the high-nutrient environments of coastal Maine and the Alexander Archipelago of southeastern Alaska are similar, the species of mink inhabiting them must, therefore in tandem, be the same. The rich environment of the coastal and littoral region has provided a mechanism to permit unusually large forms to exist. There are also qualitative characters that imply the sea mink was distinct from Mustela vison. Manly Hardy (1903) and his father worked the fur trade of Maine in the late 1800s. Having worked with more than 50,000 sea mink pelts, Hardy felt that there were distinctions between the sea mink and the typical mink (termed “woods mink” by Hardy [1903]). The fur of the sea mink was “much coarser and was of a more reddish color than that of the inland ... woods mink.... These sea mink were usually extremely fat, and the skins had an entirely different smell from that of the woods mink” (Hardy, 1903). The apparent quote by Manville (1966) and then Graham (2001) that
Hardy felt the skins of the sea mink had a “very strong peculiar, fishlike odor” is in error; Hardy (1903) never indicated this (see above quote). We feel that for the present time, it makes sense to keep the sea mink a distinct taxon and, given our present data set, we prefer a species-level designation. It certainly brings more attention to this still poorly understood animal than it would be given if it were a subspecies rank (hence Grahams letter and opposite opinion). At present time there seems to be no obvious answer other than personal opinions and personal approaches to data sets. All of Graham’s opinions and comments are well taken. We feel that whether or not the sea mink is a distinct species or a subspecies of the living mink, the animal is extinct, apparently at the hand of humans (see Hardy, 1903). We agree completely with Graham that probably the next step is for studies of the DNA and carbon isotopes to be conducted on numerous specimens of larger-than-living forms from island and coastal marine settings, on the few small forms from island settings, and on the definite in situ mainland small forms. Whether the reader feels that the sea mink is a distinct taxon or just another form of the living mink, it appears that the osteological data set will be debated until additional information becomes available. We appreciate Russ Graham’s opinions and his help in bringing attention to this unusual and inadequately understood mustelid. It is dialog such as this that promotes teamwork to solving issues around our extinct fauna of North America. REFERENCES Apollonio, S. (1979). The Gulf of Maine. Courier-Gazette, Rockland, Maine. Graham, R. W. (2001). Comment on skeleton of extinct North American sea mink (Mustela macrodon) by Jim I. Mead, Arthur E. Spiess, and Kristin D. Sobolik. Quaternary Research 53, 247–262. Hardy, M. (1903). The extinct mink from the Maine shell heaps. Forest and Stream 61, 125. Manville, R. H. (1966). The extinct sea mink, with taxonomic notes. Proceedings of the U.S. National Museum 122, 1–12. Mead, J. I., Spiess, A. E., and Sobolik, K. D. (2000). Skeleton of extinct North American sea mink (Mustela macrodon). Quaternary Research 53, 247–262. Odum, H. T., and Copeland, B. J. (1974). A functional classification of the coastal systems of the United States. In “Coastal Ecological Systems of the United States, I” (H. T. Odum, B. J. Copeland, B. J., and E. A. McMahan, Eds.), pp. 61–78. The Conservation Foundation, Washington, D.C. Odum, H. T., Copeland, B. J., and McMahan, E. A. (1974). “Coastal Ecological Systems of the United States, I.” The Conservation Foundation, Washington, D.C.
Jim I. Mead Quaternary Sciences Program and Department of Geology, Northern Arizona University, Flagstaff, Arizona 86011 E-mail: [email protected]
Arthur E. Spiess Maine Historic Preservation Commission, 55 Capitol Street, 65 State House Station, Augusta, Maine 04333
REPLY Reply to Russell Graham about Mustela macrodon One wonderful thing about science is the ability to have a difference of opinion and a variation in how one views data. In 2000 we provided an article about the description of the skeleton of the extinct sea mink, Mustela macrodon (Mead et al., 2000). We used subfossil specimens from a number of archaeological localities (from the Gulf of Maine), but in particular we used the large sample from the Turner Farm site on North Haven Island. We compared these remains of archaic age to modern skeleltons of living taxa; we wanted to find the smallest and the largest forms (subspecies) found today within the living mink, Mustela vison. Besides describing the remains from the island and some mainland coastal localities, we wanted to discuss whether the extinct sea mink should or could be a distinct form of Mustela (hence it own species designation M. macrodon; original description) or if it is just a form of extirpated living mink carrying only a subspecies rank (M. vison macrodon). We presented both hypotheses and preferred the distinct species rank instead of the subspecies designation. Graham (2001) has indicated that, “[T]he sea mink is not a valid species but should be considered a subspecies.” The discussion is dialogue about what signifies sufficient “differences” to permit a species versus subspecies designation. Whether one prefers a species rank for the sea mink or a subspecies rank of the living mink is somewhat moot; it is obvious that the living forms of mink and the extinct sea mink are very closely related. We are not making light of Graham’s view or comments, but we are not sure what the precise distinction of rank means in the case of this animal and these remains at this time. Graham (2001) pointed out that in multiple cases our graphs of the sea mink (Mead et al., 2000, Figs. 7–13) overlap with the distributions of measurements of the living subspecies. We interpreted that the larger-than-today measurements were sea mink and that those remains found to be sometimes within the range of measurements of living mink subspecies not to be of the sea mink. Graham would like to have all of our measurements to be from the sea mink (the larger representing the male, the smaller representing the female) and therefore correspond to a general continuum or clinal set of measurements—all indicating that the sea mink is merely a larger form/subspecies of living mink. This is certainly a logical, albeit narrow, view of our data— one that we were engaged with for some time before publication. However, we felt, and still feel, that there is more to the data that might imply that the sea mink is distinct from other minks. Our intent was not to create the “final say” about the sea mink, but to 0033-5894/01 $35.00 C 2001 by the University of Washington. Copyright ° All rights of reproduction in any form reserved.
bring more data to all readers to promote more discussion about this poorly known animal. We showed that when the length of the palate is compared with the width between left and right M1s (first upper molars), the single sea mink specimen available for this comparison was distinctly larger than any living form (Mead et al., 2000, Fig. 6). Certain comparisons of measurements are better than others to show the distinction of sea mink versus all other living forms of mink. There is no question that with some of the distributions of measurements, the size of the sea mink seems to blend from the largest of living forms into the high end of the cline of measurements. In other cases a cluster of measurements from the sea mink seem to be well separated from the clinal measurements obtained from the living mink forms (e.g., Mead et al., 2000, Fig. 9 [with the length and width of the m1] and Fig. 11 [the greatest length and least diameter of the radius]. Having a suite of measurements from distinct taxa that overlap in the range of measurements does not dictate that the animals must all be grouped into a single species, as Graham would imply. For instance, if one plots the length and width of the m1 (lower first molar) from well-defined species of weasels (M. nivalis [short-tailed weasel], M. erminea [ermine], and M. frenata [long-tailed weasel]), one finds that their distributions of measurements overlap yet produce a continual cline of distribution. The same thing happens when using the ranges of length from the c1-m2 and p1-m2, the length and width of the m2, and the depth and width of the mandible. The same overlap of measurements happens within these weasels with the upper dentition. According to Elaine Anderson (a recognized authority on the osteology of mustelids; personal communication, March 2001), there really is no solid osteological distinction at the species level for these weasels except when a particular measurement fits into the non-overlap zone in the clinal distribution of all measurements. Our osteological data of the sea mink would seem to mirror her conclusions. We feel that the sea mink is typically larger than all living forms of the mink; sometimes the size is at the large end of a clinal distribution and sometimes it is distinctly and significantly larger (see Mead et al., 2000, Fig. 14). We found a few qualitative characters that also seem to show some distinction between the sea mink and all living forms of M. vison (Mead et al., 2000, p. 258). We discussed that the sea mink is certainly closely related to the living form and that it even belongs to the same subgenus Vison (versus Lutreola for the European mink).
422
423
REPLY
Like Graham, we too feel that diet was the function that permitted the predominantly island-living sea mink to become distinctly larger than the inland mainland form. Without additional data (e.g., carbon isotope data) it is purely speculation as to the makeup of the diet, although we would tend to agree with Graham’s statments. It appears to us that the critical difference is not so much a mainland versus island habitat, but more of a freshwater-habitat diet versus nutrient-rich marine-habitat diet. The sea mink is found mainly on the islands and along select mainland marine coastlines where the nutrient-rich, marine habitat occurs. The rectangular depression of the Gulf of Maine, of roughly 90,700 km2 , is extremely enriched in nutrients due to the vertical and horizontal mixing of fresh and oceanic waters (Apollonio, 1979). Certain coastal ecological systems are rich in nutrients, especially those of high-energy stresses. Coastal Maine in the region containing the many offshore islands (with the sea mink remains) has nutrient diverse systems, including rocky sea fronts, high-velocity channels, tide pools, kelp beds, neutral embayments and coastal plankton, and intertidal rocky areas (Odum and Copeland, 1974). It is well known that the islands of the Alexander Archipelago (southeast Alaska and British Columbia) have an extremely high-nutrient habitat in the littoral zone (see various chapters in Odum et al., 1974). The largest of all living mink, M. vison nesolestes (see discussion in Mead et al., 2000), certainly are able to attain their great size because of the littoral marine environment in which they inhabit. For this same reason other forms of mustelids and bears (Ursus) on these islands are also some of the largest or are the largest forms for their respective species. As we indicated, island forms of Mustela vison nesolestes are larger than the nearby mainland forms of M. v. eregumenos. We would state that not only are the marine-diet sea mink larger than freshwater-diet mainland forms, but they are also larger than any mainland forms anywhere in the present distribution of M. vison, and larger than any similar island forms of M. vison anywhere in the present distribution. The present marine-diet habitat islands in southeastern Alaska still have not produced a mink as large in many aspects of the skeleton as the sea mink of Maine (Mead et al., 2000, Fig. 14). Our point here is not to conclude that because the high-nutrient environments of coastal Maine and the Alexander Archipelago of southeastern Alaska are similar, the species of mink inhabiting them must, therefore in tandem, be the same. The rich environment of the coastal and littoral region has provided a mechanism to permit unusually large forms to exist. There are also qualitative characters that imply the sea mink was distinct from Mustela vison. Manly Hardy (1903) and his father worked the fur trade of Maine in the late 1800s. Having worked with more than 50,000 sea mink pelts, Hardy felt that there were distinctions between the sea mink and the typical mink (termed “woods mink” by Hardy [1903]). The fur of the sea mink was “much coarser and was of a more reddish color than that of the inland ... woods mink.... These sea mink were usually extremely fat, and the skins had an entirely different smell from that of the woods mink” (Hardy, 1903). The apparent quote by Manville (1966) and then Graham (2001) that
Hardy felt the skins of the sea mink had a “very strong peculiar, fishlike odor” is in error; Hardy (1903) never indicated this (see above quote). We feel that for the present time, it makes sense to keep the sea mink a distinct taxon and, given our present data set, we prefer a species-level designation. It certainly brings more attention to this still poorly understood animal than it would be given if it were a subspecies rank (hence Grahams letter and opposite opinion). At present time there seems to be no obvious answer other than personal opinions and personal approaches to data sets. All of Graham’s opinions and comments are well taken. We feel that whether or not the sea mink is a distinct species or a subspecies of the living mink, the animal is extinct, apparently at the hand of humans (see Hardy, 1903). We agree completely with Graham that probably the next step is for studies of the DNA and carbon isotopes to be conducted on numerous specimens of larger-than-living forms from island and coastal marine settings, on the few small forms from island settings, and on the definite in situ mainland small forms. Whether the reader feels that the sea mink is a distinct taxon or just another form of the living mink, it appears that the osteological data set will be debated until additional information becomes available. We appreciate Russ Graham’s opinions and his help in bringing attention to this unusual and inadequately understood mustelid. It is dialog such as this that promotes teamwork to solving issues around our extinct fauna of North America. REFERENCES Apollonio, S. (1979). The Gulf of Maine. Courier-Gazette, Rockland, Maine. Graham, R. W. (2001). Comment on skeleton of extinct North American sea mink (Mustela macrodon) by Jim I. Mead, Arthur E. Spiess, and Kristin D. Sobolik. Quaternary Research 53, 247–262. Hardy, M. (1903). The extinct mink from the Maine shell heaps. Forest and Stream 61, 125. Manville, R. H. (1966). The extinct sea mink, with taxonomic notes. Proceedings of the U.S. National Museum 122, 1–12. Mead, J. I., Spiess, A. E., and Sobolik, K. D. (2000). Skeleton of extinct North American sea mink (Mustela macrodon). Quaternary Research 53, 247–262. Odum, H. T., and Copeland, B. J. (1974). A functional classification of the coastal systems of the United States. In “Coastal Ecological Systems of the United States, I” (H. T. Odum, B. J. Copeland, B. J., and E. A. McMahan, Eds.), pp. 61–78. The Conservation Foundation, Washington, D.C. Odum, H. T., Copeland, B. J., and McMahan, E. A. (1974). “Coastal Ecological Systems of the United States, I.” The Conservation Foundation, Washington, D.C.
Jim I. Mead Quaternary Sciences Program and Department of Geology, Northern Arizona University, Flagstaff, Arizona 86011 E-mail: [email protected]
Arthur E. Spiess Maine Historic Preservation Commission, 55 Capitol Street, 65 State House Station, Augusta, Maine 04333