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opencc-zeroDec 2011View details →

Data from: Interannual variation in effective number of breeders and estimation of effective population size in long-lived iteroparous lake sturgeon (Acipenser fulvescens)

Quantifying interannual variation in effective adult breeding number (Nb) and relationships between Nb, effective population size (Ne), adult census size (N) and population demographic characteristics are important to predict genetic changes in populations of conservation concern. Such relationships are rarely available for long-lived iteroparous species like lake sturgeon (Acipenser fulvescens). We estimated annual Nb and generational Ne using genotypes from 12 microsatellite loci for lake sturgeon adults (n = 796) captured during ten spawning seasons and offspring (n = 3925) collected during larval dispersal in a closed population over 8 years. Inbreeding and variance Nb estimated using mean and variance in individual reproductive success derived from genetically identified parentage and using linkage disequilibrium (LD) were similar within and among years (interannual range of Nb across estimators: 41–205). Variance in reproductive success and unequal sex ratios reduced Nb relative to N on average 36.8% and 16.3%, respectively. Interannual variation in Nb/N ratios (0.27–0.86) resulted from stable N and low standardized variance in reproductive success due to high proportions of adults breeding and the species' polygamous mating system, despite a 40-fold difference in annual larval production across years (437–16 417). Results indicated environmental conditions and features of the species' reproductive ecology interact to affect demographic parameters and Nb/N. Estimates of Ne based on three single-sample estimators, including LD, approximate Bayesian computation and sibship assignment, were similar to annual estimates of Nb. Findings have important implications concerning applications of genetic monitoring in conservation planning for lake sturgeon and other species with similar life histories and mating systems.

opencc-zeroDec 2010View details →

Data from: Population genetic analysis of white sturgeon (Acipenser transmontanus) in the Fraser River

White sturgeon (Acipenser transmontanus) in the Fraser River are listed as imperiled (the second highest possible rating) by the British Columbia Conservation Data Centre. A difficulty in trying to protect this species in the Fraser River and elsewhere is the lack of knowledge regarding their population biology. Variation in the mitochondrial DNA control region and at four microsatellite loci was examined in order to characterize white sturgeon samples from throughout the Fraser River mainstem and from a major tributary, the Nechako River. Samples from the adjacent Columbia River were analyzed for comparison. In contrast to previous work, present data indicate that white sturgeon population structure in this region reflects post-glacial dispersal more than it does recent anthropogenic effects. The data divided the Fraser into four biogeographic regions: (i) the lower Fraser, below Hell's Gate; (ii) the middle Fraser, between Hell's Gate and river km 553; (iii) the upper Fraser, above the Nechako confluence; and (iv) the Nechako River. These four groups are concordant with those suggested by tag and recapture and catch per unit effort data, and are separated by what have been identified as barriers to white sturgeon migration. Based on concordance between these different types of data, it is argued that the four groups identified here merit evolutionarily significant unit (ESU) status.

FIGURE 5 in Sturgeons (Acipenseridae) from the Late Miocene of Ukraine, with a discussion of materials associated with Widhalm's (1886) nomen nudum, †Acipenser euhuso

FIGURE 5. Isolated nearly complete "Acipenser-like" pectoral-fin spine from the Pontian of Ukraine in A, lateral, B, ventral, and C, medial views (PM ONU 3475/48). Scale bars in all equal 20 mm.

FIGURE 1 in Sturgeons (Acipenseridae) from the Late Miocene of Ukraine, with a discussion of materials associated with Widhalm's (1886) nomen nudum, †Acipenser euhuso

FIGURE 1. Palaeogeographical map of Eastern Europe (after Popov et al., 2004, modified). The yellow star in white circle indicates the studied locality.

FIGURE 12 in Sturgeons (Acipenseridae) from the Late Miocene of Ukraine, with a discussion of materials associated with Widhalm's (1886) nomen nudum, †Acipenser euhuso

FIGURE 12. Widhalm's Plate 3. A, medial view of right dentary. B, ventral view of left dentary. C, parasphenoid in ventral view. D, dorsal and E, ventral view of the dermopalatine and ectopterygoid process (terminology follows Hilton et al., 2011).

FIGURE 3 in Sturgeons (Acipenseridae) from the Late Miocene of Ukraine, with a discussion of materials associated with Widhalm's (1886) nomen nudum, †Acipenser euhuso

FIGURE 3. Fragmentary parasphenoids of a sturgeon (Acipenseridae indeterminate genus) from the Pontian of Ukraine. A, dorsal (=internal) surface of the body of the parasphenoid, proximal portions of the ascending rami, and the right posterior process (PM ONU 3475/43). B, ventral surface of the central portion of a parasphenoid, showing the aortic notch and foramina for the efferent branchial arteries (PM ONU 3475/44). C, poorly preserved posterior processes of a parasphenoid (PM ONU 3475/45). Abbreviations: an, aortic notch; arp, ascending ramus of the parasphenoid; feba, foramen for the efferent branchial artery. Scale bars in all equal 20 mm.

FIGURE 2 in Sturgeons (Acipenseridae) from the Late Miocene of Ukraine, with a discussion of materials associated with Widhalm's (1886) nomen nudum, †Acipenser euhuso

FIGURE 2. Isolated and fragmentary dermal skull of a sturgeon (Acipenseridae indeterminate genus) from the Pontian of Ukraine. A, external and B, internal surfaces of a portion of a possible parietal (PM ONU 3475/31). C, external surface of an isolated dermal bone, possibly a dorsal rostral bone (PM ONU 3475/32). D, external surface of a fragmentary posttemporal (in matrix) (PM ONU 3475/33). E, external and F, internal surfaces of a fragmentary subopercle (PM ONU 3475/34). G, external surface of a dermopterotic (in matrix) (PM ONU 3475/35). H, external surface of an unidentified dermal bone (in matrix) (PM ONU 3475/36). I, external, and J, internal surfaces of a possible median extrascapular (PM ONU 3475/37). K, L, M, N, and O, external surfaces of unidentified dermal bone (PM ONU 3475/38, 39, 40, 41, and 42, respectively). Scale bars in all equal 20 mm.

FIGURE 8 in Sturgeons (Acipenseridae) from the Late Miocene of Ukraine, with a discussion of materials associated with Widhalm's (1886) nomen nudum, †Acipenser euhuso

FIGURE 8. Isolated nearly complete "Huso-like" pectoral-fin spine from the Pontian of Ukraine in A, lateral and B, medial views (PM ONU 3475/52). Scale bars in all equal 20 mm.

FIGURE 7 in Sturgeons (Acipenseridae) from the Late Miocene of Ukraine, with a discussion of materials associated with Widhalm's (1886) nomen nudum, †Acipenser euhuso

FIGURE 7. Isolated nearly complete "Huso-like" pectoral-fin spine from the Pontian of Ukraine in A, lateral and B, medial views (PM ONU 3475/51). Scale bars in all equal 20 mm.

FIGURE 10 in Sturgeons (Acipenseridae) from the Late Miocene of Ukraine, with a discussion of materials associated with Widhalm's (1886) nomen nudum, †Acipenser euhuso

FIGURE 10. Widhalm's Plate 1. A, B, and C, D, "Huso-like" pectoral-fin spines. E-J, "Acipenser-like" pectoral-fin spines.

FIGURE 13 in Sturgeons (Acipenseridae) from the Late Miocene of Ukraine, with a discussion of materials associated with Widhalm's (1886) nomen nudum, †Acipenser euhuso

FIGURE 13. Widhalm's Plate 4. An element interpreted as a cleithrum in A, posterior, and B, anterior views. C, cleithrum in lateral view. An element interpreted as the clavicle in D, posterior and E, anterior views.

FIGURE 6 in Sturgeons (Acipenseridae) from the Late Miocene of Ukraine, with a discussion of materials associated with Widhalm's (1886) nomen nudum, †Acipenser euhuso

FIGURE 6. Isolated and fragmentary "Acipenser-like" pectoral-fin spines from the Pontian of Ukraine (in matrix). A, element in dorsal or ventral view (PM ONU 3475/49). B, element in medial view (PM ONU 3475/50). Scale bar in both equals 20 mm.

opencc-zeroDec 2022View details →

Slow heating rates increase thermal tolerance and alter mRNA HSP expression in juvenile white sturgeon (Acipenser transmontanus)

Freshwater fish such as white sturgeon (Acipenser transmontanus) are particularly vulnerable to the effects of anthropogenically induced global warming. Critical thermal maximum tests (CTmax) are often conducted to provide insight of the impacts of changing temperatures; however, little is known about how the rate of temperature increase in these assays affects thermal tolerance. To assess the effect of heating rate (0.3°C/min, 0.03°C/min, 0.003°C/min) we measured thermal tolerance, somatic indices, and Hsp mRNA expression. Contrary to what has been observed in most other fish species, white sturgeon thermal tolerance was highest at the slowest heating rate of 0.003°C/min, suggesting an ability to rapidly acclimate to slowly increasing temperatures. Hepatosomatic index decreased in all heating rates relative to control fish, indicative of the metabolic costs of thermal stress. At the transcriptional level, slower heating rates resulted in higher mRNA expression of Hsp90a, Hsp90b, and Hsp70. Hsp70 mRNA expression was increased in all heating rates relative to controls, whereas expression of Hsp90a and Hsp90b mRNA only increased in the two slower trials. Together these data indicate that white sturgeon have a very plastic thermal response, which is likely energetically costly to induce. Acute temperature changes may be more detrimental to sturgeon as they struggle to acclimate to rapid changes in their environment, however under slower warming rates they demonstrate strong thermal plasticity to warming.