Identification of microsatellite loci and examination of genetic structure for the endangered springsnails Juturnia kosteri and Pyrgulopsis roswellensis in the Chihuahuan Desert

Abstract

ABSTRACT1. Desert spring ecosystems harbour many endemic species that are threatened with extinction owing to human activities. Springsnails (superfamily Truncatelloidea) are among the most diverse freshwater snail groups in desert springs of western North America. They occupy geographically narrow ranges, often consisting of a single spring or spring complex.2. Microsatellite markers were developed via high-throughput de novo sequencing for two endangered springsnail species, Juturnia kosteri and Pyrgulopsis roswellensis, endemic to springs on Bitter Lake National Wildlife Refuge (BLNWR) near Roswell, New Mexico, USA. Genetic diversity, population structure, effective population size (N e ), and historic demography were assessed in two populations for each species.3. A large number of putative markers were identified, of which 14 loci for J. kosteri and 18 loci for P. roswellensis showed polymorphism. Genetic diversity and N e were greater in P. roswellensis than J. kosteri. Significant genetic differentiation (F ST = 0.187-0.288) was found among populations for both species, indicating currently limited gene flow. Neither species showed signs of recent population bottlenecks.4. Analyses with microsatellite markers revealed fine-scale population genetic structure in both species, unlike a previous study using mitochondrial DNA sequences. Although these species co-occur on BLNWR, slightly different genetic characteristics between them suggest that they may have different evolutionary and demographic histories. Small N e relative to census size indicates strong genetic drift in these populations. Future efforts should be directed to identifying causes of such strong drift.5. Because there are limited numbers of microsatellite markers available for springsnails, the markers identified in this study should be useful for congeners via cross-species amplification. Understanding current genetic variation and structure of these species is not only required for species recovery, but will also be useful for comparisons among many aquatic organisms endemic to springs of western North America.

Variation among macroinvertebrate communities suggests the importance of conserving desert springs

“…A similar pattern was observed in springs of the Bonneville Basin (Rader et al, 2012). (Holste, Inoue, Lang, & Berg, 2016). It is interesting that the hydrobiid Tryonia cheatumi, which is endemic to the Toyah Basin and dominated the Phantom Lake macroinvertebrate community, was also an important contributor of dissimilarity among the groups.…”

“…The taxa contributing to differences in community composition are endemic to individual spring systems, but occur in high abundances. The endemic hydrobiids at BLNWR occur at high densities (approximately 90 000 snails per m 2 ; New Mexico Department of Game and Fish, ); however, genetic analyses indicate fine‐scale population structure in both species in the Refuge (Holste, Inoue, Lang, & Berg, ). It is interesting that the hydrobiid Tryonia cheatumi , which is endemic to the Toyah Basin and dominated the Phantom Lake macroinvertebrate community, was also an important contributor of dissimilarity among the groups.…”

Use of species delimitation approaches to assess biodiversity in freshwater planaria (Platyhelminthes, Tricladida) from desert springs

“…Ethanol and formalin are the most popular reagents for long‐term preservation of field samples (Carter & Resh, ), with ethanol preservation preferred over formalin when samples are to be used for molecular analyses and DNA barcoding (Stein, White, Mazor, Miller, & Pilgrim, ). The current study was part of a biodiversity assessment of benthic macroinvertebrates in the springs of the northern Chihuahuan Desert (Adams et al, ; Ansah, Inoue, Lang, & Berg, ; Cannizzaro et al, ; Gervasio, Berg, Lang, Allan, & Guttman, ; Holste, Inoue, Lang, & Berg, ; Morningstar et al, ; Sei, Lang, & Berg, ; Seidel et al, ; Stanislawczyk et al, ); therefore, quantitative sampling followed by ethanol preservation was conducted. However, ethanol preservation methods are known to fade the coloration of body pigments (Morningstar et al, ) and cause contraction and twisting of soft bodies.…”

Characteristics, Main Impacts, and Stewardship of Natural and Artificial Freshwater Environments: Consequences for Biodiversity Conservation

“…Environmental variability can significantly influence the distribution and abundance of endemic aridland freshwater biota, such as gastropods, particularly when extremes occur simultaneously over sustained time periods [615]. In general, freshwater desert springs are highly threatened ecosystems, but they often are remarkably constant environments that contain unique faunas with many endemic, endangered, and cryptic aquatic taxa, like the endangered spring snails Juturnia kosteri ( Figure 2AI) and Pyrgulopsis roswellensis found in springs in the Chihuahuan Desert (e.g., [616,617]), owing to their isolated, island-like nature and dispersal limitations [618]. Improved protection of these sensitive freshwater ecosystems is crucial for biodiversity conservation.…”