| 1. |
- Belgrano, Andrea
(författare)
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How Fisheries Affect Evolution
- 2013
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 342, s. 1176-1177
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Annan publikation (refereegranskat)abstract
- Commercial fishing alters the genetic traits of fish stocks.
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| 2. |
- Sletvold, Nina, et al.
(författare)
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Fine-scale genetic structure in the orchid Gymnadenia conopsea is not associated with density of flowering plants
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Density-dependent pollinator visitation can lead to density-dependent mating patterns and within-population genetic structure. In Gymnadenia conopsea, individuals in low-density patches receive more self-pollen than individuals in high-density patches, suggesting higher relatedness at low density. Ongoing fragmentation is also expected to cause more local matings, potentially leading to biparental inbreeding depression. To evaluate whether relatedness decreases with local density, we analyzed 1315 SNP loci in 113 individuals within two large populations. We quantified within-population genetic structure in one of the populations, recorded potential habitat barriers, and visualized gene flow using estimated effective migration surfaces (EEMS). We further estimated the magnitude of biparental inbreeding depression resulting from matings between plants separated by maximum 5 m. There was no significant relationship between local density and relatedness in any population. We detected significant fine-scale genetic structure consistent with isolation-by-distance, with positive kinship coefficients at distances below 10 m. Kinship coefficients were low, and the predicted biparental inbreeding depression resulting from matings within the closest 5 m was a modest 1-3%. EEMS suggested that large rocks and bushes may act as barriers to gene flow within a population. The results suggest that increased self-pollen deposition in sparse patches does not necessarily lead to higher selfing rates, or that inbreeding depression results in low establishment success of inbred individuals. The modest relatedness suggests that biparental inbreeding depression is unlikely to be an immediate problem following fragmentation of large populations.
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| 3. |
- Söderquist, Linus, et al.
(författare)
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Genetic structure and diversity of the declining orchid Gymnadenia conopsea in Scandinavia: implications for conservation and management
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Understanding how historical versus contemporary processes shape population genetic structure and variation is important to design effective management actions for threatened species. To unravel population structure, connectivity, and genetic variation in the declining Gymnadenia conopsea, we genotyped 1,834 SNPs in 1,120 individuals in 110 populations, in three different habitats (fen, meadow, coastal) across Scandinavia. We further tested if genetic diversity increases with census population size, and is higher in core habitats (fen and meadow) than in marginal, coastal habitats. We identified three main genetic clusters and pronounced isolation by distance, consistent with two independent colonization routes after last glacial maximum, followed by admixture. Estimates of effective migration using EEMS indicated reduced gene flow between coastal and inland populations, suggesting that the complex topography of the fjord landscape constitutes a dispersal barrier. Genetic diversity increased with census population size. The highest genetic diversity was found in core habitats, in meadows in southern Sweden and in inland fens along the Scandes mountains, while the lowest genetic diversity was found on the Atlantic coast and in a few populations scattered across Scandinavia. Genetic diversity did not vary significantly among habitat types. In conclusion, current genetic structure suggests a strong legacy of historical events, and the high genetic diversity documented in the main Scandinavian range indicates that both current viability and future adaptation potential is high. To maintain genetic diversity and connectivity, it is particularly important to preserve southern meadow populations, which depend on traditional land use, along with central fen populations.
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| 4. |
- Söderquist, Linus, et al.
(författare)
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Population viability of the orchid Gymnadenia conopsea increases with population size but is not related to genetic diversity
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Population size is a main indicator of conservation value, thought to indicate both current and long-term population viability. However, few studies have directly examined the links between the size and the genetic and demographic properties of populations using metrics that integrate effects across the whole life cycle. In this study, we combine six years of demographic data with SNP-based estimates of genetic diversity from 18 Swedish populations of the orchid Gymnadenia conopsea, a species that is becoming increasingly rare in Europe. We investigated how population growth rate varied among populations and years, and used LTRE analysis to evaluate how underlying vital rates contribute to the variation. We examined if stochastic growth rate increased with population size and genetic diversity. For each population, we estimated the probability of quasi-extinction and of a 90% decrease in population size, within the next 30 years. Deterministic growth rate varied among populations and years, and the LTRE decomposition suggested that variation in both fecundity, and survival and growth of adults, contributed to this variation. Estimates of stochastic growth rate indicated that ten populations are declining, seven increasing, and one population approximately stable. Stochastic growth rate increased with population size, mainly due to higher survival in larger populations, but was not related to genetic diversity. One third of the populations were predicted to go extinct and eight populations to undergo a 90% decrease in population size in the coming 30 years. The results suggest that ongoing declines are not due to genetic erosion. Low survival in small populations most likely reflects a positive association between local environmental conditions and population size. More generally, the results suggest that demographic metrics can be more informative than genetic metrics, regarding conservation priority.
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| 5. |
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| 6. |
- Svensson, Ola, 1971-, et al.
(författare)
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Data from: Sympatry and parapatry among rocky reef cichlids of Lake Victoria explained by female mating preferences [Dataset]
- 2024
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Annan publikationabstract
- Work on the Lake Victoria cichlids Pundamilia nyererei (red dorsum males, deeper water), Pundamilia pundamilia (blue males, shallower water) and related species pairs has provided insights into processes of speciation. Here, we investigate female mating behaviour of five Pundamilia species and four of their F1-hybrids through mate choice trials and paternity testing. We discuss the results in the context of the geography of speciation and coexistence. Complete assortative mating was observed among all sympatric species. Parapatric species with similar depth habitat distributions interbred whereas other parapatric and allopatric species showed complete assortative mating. F1-hybrids mated exclusively with species accepted by females of the parental species. Although consistent with reinforcement in sympatry, a closer look at our results suggests otherwise and it is more likely that pre-existing female preferences influence which taxa can co-exist in sympatry. Regardless of the mechanism, mating preferences may influence species distribution in potentially hybridizing taxa, such as in the adaptive radiations of cichlid fish. We suggest that this at least partly explains why some species fail to establish breeding populations in locations where they are occasionally recorded. Our result support the notion that mating preferences of potentially cross-breeding species ought to be included in coexistence theory.
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| 7. |
- Svensson, Ola, 1971-, et al.
(författare)
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Supporting information about Pundamilia azurea, Pundamilia igneopinnis, Pundamilia nyererei, Pundamilia pundamilia and Pundamilia sp. ‘red head’ : Supplementary Material S1
- 2023
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Annan publikation (refereegranskat)abstract
- Among all known Lake Victoria haplochromines, females alone brood the eggs and fry in their mouths, occasional exceptions in the lab notwithstanding (Seehausen 1996). Free-swimming fry are guarded for a few days (Seehausen, 1996). Long-term pair bonds are unknown, and the offspring of a single clutch may be sired by multiple males (Svensson et al., 2017). Females are generally more cryptic, whereas males are larger, more conspicuous and aggressively territorial (Seehausen, 1996). The males have bright nuptial colouration of either one of three patterns that are widespread among Lake Victoria cichlid species and referred to as ‘blue’, ‘red dorsum’ or ‘red chest’ (Seehausen et al., 1998; Seehausen and van Alphen, 1999), each of which also exists in melanic forms where the underlying colour pattern can be largely disguised. Among rocky shore cichlids, these different colour pattern groups are associated with different habitats: ‘blue’ and ‘red chest’ males breed in shallow water over gently sloping substrate, ‘red dorsum’ males breed in similar habitats but deeper, and melanic forms breed even deeper or at steeply dropping rock faces (Seehausen, 1996). The five species of the present study belong to a complex of more than 20 congeneric taxa (Seehausen, 1996; Seehausen et al., 1998). They originate from south-eastern Lake Victoria (Tanzania) around islands in the Speke Gulf; Igombe Island, Makobe Island, Ruti Island, Zue Island, not further apart than 50km (Figure 1). All have similar ecology, inhabiting rocky shores and reefs and feeding largely on plankton and benthic invertebrates (Bouton et al., 1997; Maan et al., 2008; Seehausen, 1996; Seehausen et al., 1998). Their phylogenetic relationships are complicated and characterized by lineage fusion through admixture and lineage fission through speciation (Meier et al., in press).
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