Carabidae and Tenebrionidae diversity in the Great Basin Province of California.

The high desert regions of eastern California within the Great Basin are vast areas of shrub-dominated habitat heavily impacted by invasive exotic grasses and forbs. Trapping efforts within these areas provided distributional information about various surface-active arthropod taxa. Two groups with high species diversity and abundance encountered at our sites were the coleopteran families Carabidae and Tenebrionidae. Here, we report trapping of 45 species of carabids and 46 species of tenebrionids, along with mitochondrial cytochrome c oxidase subunit 1 (COI) sequence data for 65 of these 92 species. These results build upon existing distributional information regarding these families in California and further refine our knowledge of the biodiversity of the understudied Great Basin provinces.

Return of a giant: DNA from archival museum samples helps to identify a unique cutthroat trout lineage formerly thought to be extinct.

Currently one small, native population of the culturally and ecologically important Lahontan cutthroat trout (Oncorhynchus clarkii henshawi, LCT, Federally listed) remains in the Truckee River watershed of northwestern Nevada and northeastern California. The majority of populations in this watershed were extirpated in the 1940s due to invasive species, overharvest, anthropogenic water consumption and changing precipitation regimes. In 1977, a population of cutthroat trout discovered in the Pilot Peak Mountains in the Bonneville basin of Utah, was putatively identified as the extirpated LCT lacustrine lineage native to Pyramid Lake in the Truckee River basin based on morphological and meristic characters. Our phylogenetic and Bayesian genotype clustering analyses of museum specimens collected from the large lakes (1872-1913) and contemporary samples collected from populations throughout the extant range provide evidence in support of a genetically distinct Truckee River basin origin for this population. Analysis of museum samples alone identified three distinct genotype clusters and historical connectivity among water bodies within the Truckee River basin. Baseline data from museum collections indicate that the extant Pilot Peak strain represents a remnant of the extirpated lacustrine lineage. Given the limitations on high-quality data when working with a sparse number of preserved museum samples, we acknowledge that, in the end, this may be a more complicated story. However, the paucity of remnant populations in the Truckee River watershed, in combination with data on the distribution of morphological, meristic and genetic data for Lahontan cutthroat trout, suggests that recovery strategies, particularly in the large lacustrine habitats should consider this lineage as an important part of the genetic legacy of this species.

Native fishes in the Truckee River: Are in-stream structures and patterns of population genetic structure related?

In-stream structures are recognized as significant impediments to movement for freshwater fishes. Apex predators such as salmonids have been the focus of much research on the impacts of such barriers to population dynamics and population viability however much less research has focused on native fishes, where in-stream structures may have a greater impact on long term population viability of these smaller, less mobile species. Patterns of genetic structure on a riverscape can provide information on which structures represent real barriers to movement for fish species and under what specific flow conditions. Here we characterize the impact of 41 dam and diversion structures on movement dynamics under varying flow conditions for a suite of six native fishes found in the Truckee River of California and Nevada. Microsatellite loci were used to estimate total allelic diversity, effective population size and assess genetic population structure. Although there is spatial overlap among species within the river there are clear differences in species distributions within the watershed. Observed population genetic structure was associated with in-stream structures, but only under low flow conditions. High total discharge in 2006 allowed fish to move over potential barriers resulting in no observed population genetic structure for any species in 2007. The efficacy of in-stream structures to impede movement and isolate fish emerged only after multiple years of low flow conditions. Our results suggest that restricted movement of fish species, as a result of in-stream barriers, can be mitigated by flow management. However, as flow dynamics are likely to be altered under global climate change, fragmentation due to barriers could isolate stream fishes into small subpopulations susceptible to both demographic losses and losses of genetic variation.

Strong founder effects and low genetic diversity in introduced populations of Coqui frogs.

The success of non-native species may depend on the genetic resources maintained through the invasion process. The Coqui (Eleutherodactylus coqui), a frog endemic to Puerto Rico, was introduced to Hawaii in the late 1980s via the horticulture trade, and has become an aggressive invader. To explore whether genetic diversity and population structure changed with the introduction, we assessed individuals from 15 populations across the Hawaiian Islands and 13 populations across Puerto Rico using six to nine polymorphic microsatellite loci and five dorsolateral colour patterns. Allelic richness (R(T)) and gene diversity were significantly higher in Puerto Rico than in Hawaii populations. Hawaii also had fewer colour patterns (two versus three to five per population) than Puerto Rico. We found no isolation by distance in the introduced range, even though it exists in the native range. Results suggest extensive mixing among frog populations across Hawaii, and that their spread has been facilitated by humans. Like previous research, our results suggest that Hawaiian Coquis were founded by individuals from sites around San Juan, but unlike previous research the colour pattern and molecular genetic data (nuclear and mtDNA) support two separate introductions, one on the island of Hawaii and one on Maui. Coquis are successful invaders in Hawaii despite the loss of genetic variation. Future introductions may increase genetic variation and potentially its range.

PERMANENT GENETIC RESOURCES: Identification and characterization of 14 polymorphic microsatellite loci in the argasid tick Ornithodoros coriaceus.

Fourteen polymorphic microsatellite loci (di, tetra and di-tetra complexes) were developed for the argasid tick Ornithodoros coriaceus. Polymorphism was assessed for 56 individuals from two populations separated by ~95 km. All loci were polymorphic (X = 7, range 3-17 alleles). All loci were in Hardy-Weinberg equilibrium except for one locus (OrC 8) in a single population (P < 0.00119, after Bonferroni correction for multiple tests).