Museum collections are critical to contemporary biological research, but museum acquisitions have declined in recent decades, hampering researchers' ability to use collections to assess species responses to habitat modification, urbanization, and global climate change. Citizen science may be a key method to bolster museum collections data, particularly from urban regions, where ongoing data collection is critical to our understanding of ecosystem dynamics in a highly modified and variable landscape. In this study, we compare data collected as part of the citizen-science project Reptiles and Amphibians of Southern California (RASCals), hosted on the platform iNaturalist (www.inaturalist.org), to data in the VertNet database (www.vertnet.org), which houses millions of museum collection records from over 250 natural-history collections, for four focal species, including a native lizard of conservation concern that has declined with urbanization, a native lizard that is widespread in urban areas, and two invasive aquatic species. We compared numbers of VertNet records over time to modern RASCals records, and the number of records collected from urban, suburban, and protected areas from both databases. For all species, citizen-science records were generated much more rapidly than museum records. For three of our four focal species, RASCals participants over 27 months documented from 70 to 750% more records than were added to the VertNet database after 1990. For the urban-tolerant southern alligator lizard, RASCals participants collected nearly 45 times more modern urban records than are contained in the VertNet database. For all other species, the majority of RASCals records were collected within suburban or other highly modified landscapes, demonstrating the value of citizen science for collecting data within urban and suburban ecosystems. As new museum acquisitions decline, citizen-science projects like RASCals may become critical to the maintenance of modern species-distribution data.

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Hybrid zones act as natural laboratories where divergent genomes interact, providing powerful systems for examining the evolutionary processes underlying biological diversity. In this study, we characterized patterns of genomic and phenotypic variation resulting from hybridization between divergent intraspecific lineages of the Neotropical red‐eyed treefrog (Agalychnis callidryas). We found genetic evidence of a newly discovered contact zone and phenotypic novelty in leg colour—a trait suspected to play a role in mediating assortative mating in this species. Analysis of hybrid ancestry revealed an abundance of later‐generation Fn individuals, suggesting persistence of hybrids in the contact zone. Hybrids are predominantly of southern ancestry but are phenotypically more similar to northern populations. Genome‐wide association mapping revealed QTL with measurable effects on leg‐colour variation, but further work is required to dissect the architecture of this trait and establish causal links. Further, genomic cline analyses indicated substantial variation in patterns of introgression across the genome. Directional introgression of loci associated with different aspects of leg colour are inherited from each parental lineage, creating a distinct hybrid colour pattern. We show that hybridization can generate new phenotypes, revealing the evolutionary processes that potentially underlie patterns of phenotypic diversity in this iconic polytypic frog. Our study is consistent with a role of hybridization and sexual selection in lineage diversification, evolutionary processes that have been implicated in accelerating divergence in the most phenotypically diverse species.

Geographic variation in courtship behavior can affect reproductive success of divergent phenotypes via mate choice. Over time, this can lead to reproductive isolation and ultimately to speciation. The Neotropical red-eyed treefrog (Agalychnis callidryas) exhibits high levels of phenotypic variation among populations in Costa Rica and Panama, including differences in color pattern, body size, and skin peptides. To test the extent of behavioral premating isolation among differentiated populations, we quantified male advertisement calls from six sites and female responses to male stimuli (acoustic and visual signals) from four sites. Our results show that both male advertisement calls and female behavior vary among populations: Discriminant function analyses can predict the population of origin for 99.3% ± 0.7 of males based on male call (dominant frequency and bandwidth) and 76.1% ± 6.6 of females based on female response behavior (frequency and duration of visual displays). Further, female mate choice trials (n = 69) showed that population divergence in male signals is coupled with female preference for local male stimuli. Combined, these results suggest that evolved differences among populations in male call properties and female response signals could have consequences for reproductive isolation. Finally, population variation in male and female behavior was not well explained by geographic or genetic distance, indicating a role for localized selection and/or drift. The interplay between male courtship and female responses may facilitate the evolution of local variants in courtship style, thus accelerating premating isolation via assortative mating.

Urbanization brings the introduction of roads and anthropogenic noise. Noise has negative health outcomes across vertebrates. White's treefrogs (Litoria caerulea) exposed to ecologically relevant levels of traffic noise for one week had elevated circulating corticosterone levels and decreased sperm count and sperm viability relative to controls.

Many organisms depend on acoustic communication for myriad functions, and have evolved behaviours to minimize effects of naturally occurring acoustic interference. However, as habitats are subject to increased alteration, anthropogenic noise becomes unavoidable, and how animals overcome such interference is not well understood. In most ecosystems, only a subset of frog species is associated with disturbed habitats; the ability of these species to overcome exogenous noise suggests that habitat associations may be related to species' response to noise. We tested the hypothesis that frogs associated with largely undisturbed forest habitat would be less likely to increase call output in response to exogenous noise than would those associated with disturbed or open habitat. While this relationship was not significant, we found a slight trend supporting the hypothesis. We then asked whether anthropogenic noise affects chorus tenure at individual- or at chorus-levels. Male frogs exposed to anthropogenic noise decreased both the number of days present at the chorus and the nightly chorus duration relative to controls. Because females generally join choruses late at night to breed, the effects of noise shown here are likely to substantially decrease frog reproductive success; thus, the acoustic environment may play an important role in shaping population dynamics and in amphibian declines.

The laminar scales of the fern Elaphoglossum paleaceum were studied to determine if they act as a morphological mechanism to protect leaves from excess light. We hypothesized that if scales serve this purpose, then individual plants growing in high light would have greater laminar scale density than those in low light. For our first experiment, plants from high light roadsides were collected and subjected to artificial scale removal and then exposed to super-saturating pulse of light for 30 min. We found that leaves with their scales removed exhibited significantly greater photoinhibition than leaves with scales intact. Leaves with intact scales recovered fully after twelve hours whereas those with scales removed remained photoinhibited. Scale density on the adaxial side of leaves was positively correlated with light intensity. The data from this study indicate that fern laminar scales help redu[:e photoinhibition and potentially function as a morphological defense against photodamage.The function of leaf vestiture has long been a hotanical curiosity. Apart from their utility for taxonomic purposes, leaf hairs and scales play many roles that directly influence plant physiology (