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elated haplotypes (B, D, E) accounted for 80% of the individuals in the Galveston sample whereas no<br />
single haplotype was dominant at Port Aransas or South Padre Island (Table 5, Fig. 22, 23).<br />
There was little genetic distance among samples (Fig. 24). Genetic distances ranged from 0.005<br />
between Florida-Galveston to 0.011 between Galveston-Port Aransas and Port Aransas-South Padre Island<br />
(Table 6) and averaged 0.009 (S.E.=0.003). Mantel’s test generated a correlation coefficient of -0.217, to<br />
indicate no significant relationship (p≥0.658) between genetic distance and geographic distance. AMOVA<br />
revealed that samples from Florida and Galveston were statistically similar (p>0.58) as were Port Aransas<br />
and South Padre Island (p>0.23). No such similarity (p≤0.01) was found between Florida or Galveston<br />
samples and those of Port Aransas and South Padre Island (Table 6). While the majority of variance<br />
(80%) could be accounted for within samples, a significant portion (20%) was attributed to among group<br />
variance (Φ ST ) corresponding to the differentiation between Florida-Galveston and Port Aransas-South<br />
Padre Island. The Φ ST values, in ranging from –0.24 to 0.30, indicated low levels of population structure<br />
(Table 6). Number of migrants per generation (N m ) was high between Florida-Galveston (∞) and Port<br />
Aransas-South Padre Island (55.6) but an order of magnitude lower among other site comparisons that<br />
ranged from 3.8 for Galveston-South Padre Island to 1.2 between Florida-Port Aransas (Table 6). This<br />
gene flow did not prevent Florida and Galveston samples from exhibiting a haplotype frequency distinct<br />
from those in south Texas (Fig. 22, 23).<br />
Table 6. Genetic isolation of <strong>Scartella</strong> <strong>cristata</strong> at Gulf of Mexico study sites relative to geographic distance between sites.<br />
Linear distances (km) between pairs of study sites, Tamura-Nei genetic distance (d), the among-group component of genetic<br />
variation (Φ ST ), a statistical test based on haplotype frequency shifts and an estimate of gene flow in terms of the number of<br />
migrants per generation (N m ) are presented.<br />
LOCATIONS DISTANCE (km) d F ST EXACT TEST N m<br />
Florida-Galveston 689 0.005 -0.24 (p >0.58) 8<br />
Florida-Port Aransas 763 0.011 0.30 (p
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