Fragmented habitat compensates for the adverse effects of genetic bottleneck

Löytynoja, Ari; Rastas, Pasi; Valtonen, Mia; Kammonen, Juhana; Olsen, Morten Tange; Paulín, Lars; Jernvall, Jukka; Auvinen, Petri

doi:10.1016/j.cub.2023.01.040

Cited by 4 publications

(19 citation statements)

References 40 publications

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“…Figure S4.5) suggest a higher proportion of Baltic ancestry within Lake Ladoga than within Saimaa. These latter patterns resemble results from genetic analyses of the seal hosts (Löytynoja et al, 2023;Nyman et al, 2014). The possibility of upstream gene flow from the Baltic Sea to Lake Ladoga is supported by our finding that the C. semerme population of the lake is likewise weakly differentiated from the one infesting Baltic ringed seals (Figure 4b).…”

Section: Host and Corynosoma Population-genetic Structuresupporting

confidence: 84%

“…These two seal host species differ in their dietary preferences (Scharff-Olsen et al, 2019), but at least in the case of C. strumosum and C. semerme, the wide range of paratenic hosts (Anikieva et al, 2018;Leidenberger et al, 2020;Sinisalo et al, 2003;Valtonen et al, 2001) The genetic similarity of the C. strumosum populations in lakes Saimaa and Ladoga (Figures 3 and 4) is surprising because it contrasts with the postglacial emergence history of the lakes. Lake Saimaa was formed and presumably colonized by ringed seals thousands of years before the separation of Lake Ladoga from the Baltic Sea basin, meaning that the divergence of the Saimaa population should precede the split of the Ladoga and Baltic Sea populations (Löytynoja et al, 2023;Saarnisto, 2011;Ukkonen et al, 2014). The two lakes are connected by the c. 150 km long Vuoksi River, which, even before the construction of a series of hydroelectric dams from the 1920s onwards (Jormola et al, 2016), was impassable for seals due to its many steep rapids.…”

Section: Host and Corynosoma Population-genetic Structurementioning

confidence: 99%

“…In the TCS network based on COI barcode sequences, the C. While similar replacement of the Baltic ringed seal population is not apparent in archeological data (Ukkonen et al, 2014), recent genetic studies have increasingly converged toward the conclusion that the genetic composition of the extant Baltic ringed seal population differs from the one that was present during colonization of Lake Saimaa (Heino et al, 2023;Löytynoja et al, 2023). As pointed out by Whiteman and Parker (2005), genetic analyses of host-specific parasites provide a potentially powerful tool for illuminating both deep evolutionary histories and recent population subdivisions of their hosts (see also Gagne et al, 2022;Koop et al, 2014;Nieberding & Olivieri, 2007;Whiteman et al, 2007).…”

Section: Host and Corynosoma Population-genetic Structurementioning

confidence: 99%

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Loss of species and genetic diversity during colonization: Insights from acanthocephalan parasites in northern European seals

Sromek,

Ylinen,

Kunnasranta

et al. 2023

Ecology and Evolution

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Studies on host–parasite systems that have experienced distributional shifts, range fragmentation, and population declines in the past can provide information regarding how parasite community richness and genetic diversity will change as a result of anthropogenic environmental changes in the future. Here, we studied how sequential postglacial colonization, shifts in habitat, and reduced host population sizes have influenced species richness and genetic diversity of Corynosoma (Acanthocephala: Polymorphidae) parasites in northern European marine, brackish, and freshwater seal populations. We collected Corynosoma population samples from Arctic, Baltic, Ladoga, and Saimaa ringed seal subspecies and Baltic gray seals, and then applied COI barcoding and triple‐enzyme restriction‐site associated DNA (3RAD) sequencing to delimit species, clarify their distributions and community structures, and elucidate patterns of intraspecific gene flow and genetic diversity. Our results showed that Corynosoma species diversity reflected host colonization histories and population sizes, with four species being present in the Arctic, three in the Baltic Sea, two in Lake Ladoga, and only one in Lake Saimaa. We found statistically significant population‐genetic differentiation within all three Corynosoma species that occur in more than one seal (sub)species. Genetic diversity tended to be high in Corynosoma populations originating from Arctic ringed seals and low in the landlocked populations. Our results indicate that acanthocephalan communities in landlocked seal populations are impoverished with respect to both species and intraspecific genetic diversity. Interestingly, the loss of genetic diversity within Corynosoma species seems to have been less drastic than in their seal hosts, possibly due to their large local effective population sizes resulting from high infection intensities and effective intra‐host population mixing. Our study highlights the utility of genomic methods in investigations of community composition and genetic diversity of understudied parasites.

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Section: Host and Corynosoma Population-genetic Structuresupporting

confidence: 84%

Section: Host and Corynosoma Population-genetic Structurementioning

confidence: 99%

Section: Host and Corynosoma Population-genetic Structurementioning

confidence: 99%

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Loss of species and genetic diversity during colonization: Insights from acanthocephalan parasites in northern European seals

Sromek,

Ylinen,

Kunnasranta

et al. 2023

Ecology and Evolution

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“…As shown by our analyses (Fig. 1D), the metapopulation level estimates effectively hide much of the demographically driven variance in nucleotide diversity and can be substantially larger than they would be in a panmictic population of the same size (Löytynoja et al 2023).…”

Section: Discussionmentioning

confidence: 65%

Determinants of genetic diversity in sticklebacks

Kivikoski

Feng

Löytynoja

et al. 2023

Preprint

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Understanding what determines species and population differences in levels of genetic diversity has important implications for our understanding of evolution, as well as for the conservation and management of wild populations. Previous comparative studies have emphasized the roles of linked selection, life-history trait variation and genomic properties, rather than pure demography, as important determinants of genetic diversity. However, these findings are based on coarse estimates across a range of highly diverged taxa, and it is unclear how well they represent the processes within individual species. We assessed genome-wide genetic diversity (pi) in 45 nine-spined stickleback (Pungitius pungitius) populations and found that pi varied 15-fold among populations (pi min approx. 0.00015, pi max approx 0.0023) whereas estimates of recent effective population sizes varied 122-fold. Analysis of inbreeding coefficients (F ROH) estimated from runs of homozygosity revealed strong negative association between pi and F ROH. Genetic diversity was also negatively correlated with mean body size and longevity, but these associations were not statistically significant after controlling for demographic effects (F ROH). The results give strong support for the view that populations' demographic features, rather than life history differences, are the chief determinants of genetic diversity in the wild.

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“…In both specimens, there was also an aplasia of the rostral cerebral artery (Figure 1). These individuals were collected from different parts of Lake Saimaa, indicating that the anomalies were not related to a geographically subdivided local population in the complex lake system (Löytynoja et al, 2023; Palo et al, 2003). It is interesting to consider in this context that Lake Saimaa is very shallow, with a mean depth of 12 meters (maximum 85 m; Kunnasranta et al, 2021).…”

Section: Discussionmentioning

confidence: 99%

Anatomical variations in the cerebral arterial circle of the Saimaa (Pusa hispida saimensis) and Baltic ringed seals (Pusa hispida botnica)

Laakkonen,

Nihtilä,

Jernvall

2023

The Anatomical Record

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The intracranial arterial vascularization of the Saimaa ringed seals (Pusa hispida saimensis; Nordquist, 1899) and Baltic ringed seals (Pusa hispida botnica; Gmelin, 1788) disclosed patterns of anatomical architecture comparable to that of other pinniped species. Arterial silicone casts on skull scaffolds, and magnetic resonance imaging (MRI) showed that the besides joining the caudal communicating arteries upon entering the cerebral arterial circle, the bilateral internal carotid arteries bifurcated as laterally oriented rostral choroidal arteries and rostral cerebral arteries. The latter arteries almost immediately gave off the laterally oriented middle cerebral arteries. Numerous individual variations were evident in differences in the exact branching sites of bilateral vessels or the size or number of arterial branches. Two Saimaa ringed seals had only a tiny foramen for the left internal carotid artery to enter the intracranial space, and the intracranial part of this vessel was short. It did not reach the cerebral arterial circle. The intracranial part of the right internal carotid artery is bifurcated and also supplied the left side of the cerebral arterial circle. Both specimens had aplasia of the left rostral cerebral artery. The intracranial arterial arrangement of Saimaa and Baltic ringed seals reflects the arterial architecture of this body region in terrestrial mammals with little evidence for aquatic adaptations or changes related to thermoregulation.

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Fragmented habitat compensates for the adverse effects of genetic bottleneck

Cited by 4 publications

References 40 publications

Loss of species and genetic diversity during colonization: Insights from acanthocephalan parasites in northern European seals

Loss of species and genetic diversity during colonization: Insights from acanthocephalan parasites in northern European seals

Determinants of genetic diversity in sticklebacks

Anatomical variations in the cerebral arterial circle of the Saimaa (Pusa hispida saimensis) and Baltic ringed seals (Pusa hispida botnica)

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