Data with corrected number of bivalve individuals (sampling domain 3x size of observed collections)

This table provides the numbers of living and dead individuals of all mollusc taxa that were recovered in benthic assemblages, listed separately for all censuses. Individual numbers are corrected for disarticulated valves of single bivalve individuals by assuming sampling domains three times the size of an observed collection. This dataset was used for all analyses presented in the manuscript

Data from: Increase in multiple paternity across the reproductive lifespan in a sperm-storing, hermaphroditic freshwater snail

Polyandry is a common phenomenon and challenges the traditional view of stronger sexual selection in males than in females. In simultaneous hermaphrodites, the physical proximity of both sex functions was long thought to preclude the operation of sexual selection. Laboratory studies suggest that multiple mating and polyandry in hermaphrodites may actually be common, but data from natural populations are sparse. We therefore estimated the rate of multiple paternity and its seasonal variability in the annual, sperm-storing, simultaneously hermaphroditic freshwater snail Radix balthica for the entire duration of the reproductive lifespan. We also tested whether multiple paternity was associated with clutch size or embryonic development. To obtain these data, we measured and genotyped 60 field-collected egg clutches using nine highly polymorphic microsatellite markers. Overall, 50% of the clutches had multiple fathers, and both the frequency (20–93% of clutches) and magnitude of multiple paternity (mean 1.3–3.8 fathers per clutch) substantially increased over time, probably because of extensive sperm storage. Most multiply sired clutches (83%) had a dominant father, but neither clutch size nor the proportion of developed embryos per clutch was associated with levels of multiple paternity. Both the evident promiscuity and the frequent skew of paternity shares suggest that sexual selection may be an important evolutionary force in the study population

Data with maximum number of bivalve individuals (XNI approach)

This table provides the raw numbers of living and dead specimens of all mollusc taxa that were recovered in benthic assemblages, listed separately for all censuses. Individual numbers are uncorrected for disarticulated valves of single bivalve individuals. As each empty bivalve valve was assumed to represent a unique individual ("XNI approach"), this dataset thus provides the maximum number of bivalve individuals

Data with minimum number of bivalve individuals (MNI approach)

This table provides the numbers of living and dead specimens of all mollusc taxa that were recovered in benthic assemblages, listed separately for all censuses. Individual numbers are corrected for disarticulated valves of single bivalve individuals by assuming that both empty valves of all dead bivalve individuals were present in a sample ("the MNI approach"). This dataset thus provides the minimum number of bivalve individuals

Data from: Explaining high-diversity death assemblages: undersampling of the living community, out-of-habitat transport, time-averaging of rare taxa, and local extinction

Molluscan benthic assemblages provide unique opportunities for understanding both spatial and temporal patterns of biodiversity. Species richness in the shell remains found at a site (i.e. the death assemblage) is typically several times higher than in the counterpart living assemblage, reflecting a complex history of settlement, dissemination and decomposition post-mortem. We used high-density temporal and spatial sampling (>37’000 individuals representing 196 taxa) of a shallow (5-8 m) nearshore sandy habitat off the coast of south-east Sardinia (Italy, Mediterranean Sea) to study the factors responsible for differences in the relative diversity of living and death assemblages. We found that death assemblages at all sites were considerably more diverse than living communities (1.5-3.5x more dead than living taxa after sample-size standardization), with 78% of all taxa solely recovered as empty shells, resulting in low live-dead agreement. By carefully filtering the raw data and combining them with habitat information extracted from the literature, we disentangled the major causes of this discordance and quantified their individual effects. Increased dead diversities could not be attributed to undersampling of the living community, but instead resulted from three phenomena of decreasing importance: the post-mortem, out-of-habitat transport of non-indigenous taxa (57% of dead-only taxa were allochthonous), the time-averaged presence of rare indigenous taxa (40% of dead-only taxa), and the likely local extirpation of a small number of species (3% of dead-only taxa). Our approach demonstrates how ecological inferences based on death assemblages can be improved by restricting analyses to demonstrably indigenous taxa, and highlights how mollusc shell remains can be used to provide information over both ecological and evolutionary timescales

Characteristics of 201 field-collected egg clutches

This file provides for each of 201 field-collected egg clutches the collection date, number of eggs, number of developed and undeveloped embryos, and (for clutches of which embryos were genotyped) two estimates of the number of fathers that sired the clutch, one obtained from using the parentage analysis software COLONY version 2.0.5.9 and one obtained from simple allele counting

Shell lengths of 1013 field-collected snails

This file provides the collection date and shell length for each of 1013 adult field-collected snails

Data from: Comparing direct and indirect selfing rate estimates: when are population-structure estimates reliable?

The rate of self-fertilization (that is, selfing) is a key evolutionary parameter in hermaphroditic species, yet obtaining accurate estimates of selfing rates in natural populations can be technically challenging. Most published estimates are derived from population-level heterozygote deficiency (that is, FIS) or identity disequilibria (for example, the software RMES (robust multilocus estimate of selfing)). These indirect methods can be applied to population genetic survey data, whereas direct methods using progeny arrays require much larger data sets that are often difficult to collect in natural populations or even require captive breeding. Unfortunately, indirect methods rely on assumptions that can be problematic, such as negating biparental inbreeding, inbreeding disequilibrium and (for FIS) the presence of null alleles. The performance of indirect estimates against progeny-array estimates is still largely unknown. Here we used both direct progeny-array and indirect population-level methods to estimate the selfing rate in a single natural population of the simultaneously hermaphroditic freshwater snail Radix balthica throughout its reproductive lifespan using 10 highly polymorphic microsatellites. We found that even though progeny arrays (n=1034 field-collected embryos from 60 families) did not reveal a single selfed embryo, FIS-based selfing rates (n=316 adults) were significantly positive in all 6 sequential population samples. Including a locus with a high frequency of null alleles further biased FIS-based estimates. Conversely, RMES-based estimates were very similar to progeny-array estimates and proved insensitive to null alleles. The assumptions made by RMES were thus either met or irrelevant in this particular population, making RMES a valid, cost-efficient alternative to progeny arrays

Microsatellite genotype data for 316 adult field-collected snails

This file contains the microsatellite genotypes of 316 adult snails that were collected at six different dates from a single population (Uerikon) in Lake Zurich, Switzerland. Each snail was genotyped for ten microsatellite loci

Microsatellite genotype data for 1034 snail embryos from 60 field-collected clutches

This file contains the microsatellite genotypes of 1034 snail embryos from a total of 60 egg clutches. Clutches were collected at four different dates from a single population (Uerikon) in Lake Zurich, Switzerland. Each snail embryo was genotyped for ten microsatellite loci