Figure 1: Haplotype frequency distribution for 104 individuals of the planktonic
marine copepod, Calanus finmarchicus, in samples collected from the
coastal western North Atlantic Ocean and Norwegian Sea. The frequency
distribution is strongly skewed, with one abundant, nearly ubiquitous haplotype
and numerous unique haplotypes. This haplotype frequency distribution is
typical of the seven planktonic crustaceans that have been studied.
Figure 2: Numbers of individuals of each haplotype for Calanus
finmarchicus by region for samples collected in 1992. The samples
within each region were pooled to show regional patterns of haplotype
distributions. The regions (and the numbers of individuals sequenced,
N) are: the Gulf of St. Lawrence (left symbol: N=17), the northern
Gulf of St. Lawrence (right symbol: N=8), Georges Bank (N=28),
Wilkinson Basin in the Gulf of Maine (N=19), and the Norwegian Sea
(N=32). Two symbols are shown for the Gulf of St. Lawrence since
one sample was genetically distinctive from all others.
Figure 3: Phylogeographic tree showing patterns of molecular variation
in the planktonic calanoid copepod, Nannocalanus minor, in the
Gulf Stream System. Molecular genetic traits separated the species
into two distinct groups (a larger, western form and a smaller, eastern
form) which differed by 10% of the bases in a region of mitochondrial
DNA. This level of base sequence variation is far larger than that
typical between conspecific populations; it suggests that the forms
are actually different species. Within the western form, there were no
[4]
Figure 3: Figure 3 continued.
significant differences in haplotype frequencies between samples
collected from the Florida Straits (shown as circles) and the meander
region of the Gulf Stream (shown as squares); sequence variation between
individuals of the larger form was <1%. Numbers following the
circles and squares indicate the numbers of individuals sequenced
from each of the regions; symbols that are not followed by a number
represent one individual; numbers on horizontal branches are branch
lengths. (See Saitou and Nei [1987] for a discussion of tree
building techniques.)
Figure 4: (A) Distributions of the subspecies of the planktonic copepod,
Calanus pacificus, in the North Pacific Ocean. Collection locations of samples
for molecular analysis are indicated by symbols. [Distribution map is after
unpublished work of Abraham Fleminger, Scripps Institution of Oceanography
(deceased).] (B) Phylogeographic tree showing molecular variation between
individuals of the planktonic calanoid copepod, Calanus pacificus,
collected from different locations in the North Pacific Ocean. The
molecular analysis
[4]
Figure 4: Figure 4 continued.
supported the division of C. p. californicus
(samples CCS and PUGET) and C. p. pacificus (PAPA). Sequence
divergence between the subspecies was low (around 1%), which is typical
of intraspecific divergences, but the C. p. pacificus individuals
grouped on a distinct branch of the tree and there was no overlap in the
haplotypes, suggesting that these differences are greater than typically
found between conspecific populations. Some geographic partitioning
within
[4]
Figure 4: Figure 4 continued.
C. p. californicus is
suggested by the arrangement of individuals on the tree branches,
but confirmation will require larger sample sizes. Symbols on the
tree correspond to collection sites; individuals are named by collection
site with a final number or letter to denote that individual; numbers
at branch points are the percentage of trees showing that branchpoint
in 1000 bootstrapped subreplicates. (See Saitou and Nei [1987]
for a discussion of tree-building techniques.)