Naturalist - Tracks and Shadows: Field Biology as Art - page 17

in all of those places, how many species are there, and what accounts for their diversi-
fication?
Henry knew from his Oregon childhood that certain gartersnakes were associated
with particular habitats and diets. Thamnophis ordinoides hydrophila was abundant
along rocky streams and ate fish and tadpoles; T. o. elegans was scarcer, found in dry
oak woods, and fed on lizards and mice; and T. o. ordinoides lived in low, wet places
but didn't enter water, and subsisted on slugs. By concentrating on areas with two or
more “kinds,” Henry hoped to determine whether they were geographical races of the
same species (also called subspecies) or separate species. He examined almost three
thousand specimens, of which he'd personally collected about 850 at 150 localities; he
recorded scale counts, head length, and so forth, and for live snakes wrote descriptions
of behavior and color patterns. He thus benefited from having far more field experience
and data than previous researchers, and as a result he uncovered differences that made
sense in terms of ecology.
Grinnell and Miller regarded distinctive populations from different places as separ-
ate species (a view that made them, in taxonomic vernacular, “splitters”), whereas some
contemporaries (“lumpers”) believed that reasonably similar organisms likely could in-
terbreed and so should be treated as subspecies. Henry accordingly viewed Thamnoph-
ishammondii in southern California and T.digueti in Baja California as distinct from an
otherwise widespread T. ordinoides; the latter encompassed four terrestrial and three
aquatic subspecies, including two new ones that he named T.o.hydrophila (“water lov-
er”) and T.o.gigas, the Central Valley's watersnake-like giant. Moreover, he described a
scenario wherein various pairs among the seven races met and produced intermediate
individuals at some places, as predicted by the lumpers, while elsewhere two subspe-
cies abutted with little or no evidence of hybrids, implying speciation. His dissertation
referred to the entire complex as an Artenkreis, a German word for closely related, in-
teracting species.
Henry also contradicted Ruthven's views on evolution. Despite the Michigan herpet-
ologist's lack of field experience with western gartersnakes, he presaged an anti-ad-
aptationism popularized decades later by Harvard's Stephen Jay Gould, arguing that
tendencies to dwarfism rather than natural selection drove diversification. Conversely,
Henry's data—he had 945 prey items from the stomachs of 462 individual garter-
snakes—suggested that size, shape, and anatomy are related to environmental factors,
implying selection. Large forms have stout bodies, more scale rows, unicolored or
checkered patterns, small lip scales and salivary glands, and long, narrow heads, all of
which might facilitate aquatic habits and a diet of bulky fish. Their more slender ter-
restrial kin, with fewer scale rows, bright stripes, large lip scales and salivary glands,
and short, blunt heads, feed on worms, slugs, and frogs.
After receiving his doctorate in the spring of 1937, Henry worked at M.V.Z.'s new
Hastings Natural History Reservation in Carmel Valley while preparing the dissertation
for publication. Linsdale was a staff researcher there and notoriously unpleasant, but
Henry laughed of the older man's endless criticism for the sake of his guidance in
conducting field studies. By then the new Ph.D. had caught the attention of prominent
herpetologists, and his professor was unequivocally impressed. Karl Schmidt of Chica-
go's Field Museum of Natural History called Henry “one of the most promising younger
herpetologists,” and Grinnell responded that he'd “never known so energetic and ef-