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Anthropogenically fragmented populations may have reduced fitness due to loss of genetic diversity and inbreeding. The extent of such fitness losses due to fragmentation and potential gains from conservation actions are infrequently assessed together empirically. Controlled crosses within and among populations can identify whether populations are at risk of inbreeding depression and whether inter-population crossing alleviates fitness loss. Because fitness depends on the environment and life stage, studies quantifying cumulative fitness over a large portion of the lifecycle in conditions that mimic natural environments are most informative. To assess the fitness consequences of habitat fragmentation, we leveraged controlled within-family, within-population, and between-population crosses to quantify inbreeding depression and heterosis in seven populations of Echinacea angustifolia within a 6,400-ha area. We then assessed cumulative offspring fitness after 14 yr of growth in a natural experimental plot (N = 1,136). The mean fitness of progeny from within-population crosses varied considerably, indicating genetic differentiation among source populations, even though these sites are all less than 9 km apart. The fitness consequences of within-family and between-population crosses varied in magnitude and direction. Only one of the seven populations showed inbreeding depression of high effect, while four populations showed substantial heterosis. Outbreeding depression was rare and slight. Our findings indicate that local crossings between isolated populations yield unpredictable fitness consequences ranging from slight decreases to substantial increases. Interestingly, inbreeding depression and heterosis did not relate closely to population size, suggesting that all fragmented populations could contribute to conservation goals as either pollen recipients or donors. 

Abstract PremiseUnderstanding how population dynamics vary in space and time is critical for understanding the basic life history and conservation needs of a species, especially for narrow endemic species whose populations are often in similar environments and therefore at increased risk of extinction under climate change. Here, we investigated the spatial and temporal variation in population dynamics ofRanunculus austro‐oreganus, a perennial buttercup endemic to fragmented prairie habitat in one county in southern Oregon. MethodsWe performed demographic surveys of three populations ofR. austro‐oreganusover 4 years (2015–2018). We used size‐structured population models and life table response experiments to investigate vital rates driving spatiotemporal variation in population growth. ResultsOverall,R. austro‐oreganushad positive or stable stochastic population growth rates, though individual vital rates and overall population growth varied substantially among sites and years. All populations had their greatest growth in the same year, suggesting potential synchrony associated with climate conditions. Differences in survival contributed most to spatial variation in population growth, while differences in reproduction contributed most to temporal variation in population growth. ConclusionsPopulations of this extremely narrow endemic appear stable, with positive growth during our study window. These results suggest that populations ofR. austro‐oreganusare able to persist if their habitat is not eliminated by land‐use change. Nonetheless, its narrow distribution and synchronous population dynamics suggest the need for continued monitoring, particularly with ongoing habitat loss and climate change. 

Pseudo-nitzschia harmful algal blooms have recently caused elevated domoic acid in coastal environments of the Northeast United States. In 2017, the toxigenic species P. australis was observed in Narragansett Bay, Rhode Island, a temperate estuarine ecosystem, for the first time since 2009 when DNA monitoring for Pseudo-nitzschia species began. This highly toxic species likely contributed to toxin-related shellfish harvest closures and is hypothesized to have been introduced by an offshore source. Little is known about offshore Pseudo-nitzschia spp. populations in the Northeast Continental Shelf marine ecosystem or how often toxigenic species enter Narragansett Bay through physical processes. Here, we collected filtered biomass samples from multiple time series sites within Narragansett Bay and along the Northeast U.S. Shelf Long-Term Ecological Research transect in winter and summer to investigate the frequency and seasonality of potential Pseudo-nitzschia spp. inflow from the continental shelf to the estuary. Species were taxonomically identified using DNA sequencing of the ITS1 region and domoic acid concentrations were quantified by liquid chromatography with tandem mass spectrometry and multiple reaction monitoring. During six years of sampling, Pseudo-nitzschia species assemblages were more similar between Narragansett Bay and the Northeast shelf in winter than summer, suggesting greater ecosystem connectivity in winter. These winter assemblages were often accompanied by higher domoic acid. Several Pseudo-nitzschia species co-occurred most often with domoic acid and were likely responsible for toxin production in this region, including P. pungens var. pungens, P. multiseries, P. calliantha, P. plurisecta, P. australis, and P. fraudulenta. Domoic acid was detected during periods of relatively low macronutrient concentrations in both seasons, warmer sea surface temperatures in winter, and colder temperatures in summer within this dataset. This study represents some of the first domoic acid measurements on the offshore Northeast U.S. Continental Shelf, a region that supplies water to other coastal environments and could seed future harmful algal blooms. The elevated domoic acid and frequency of hypothesized inflow of toxigenic Pseudo-nitzschia spp. from the Northeast continental shelf to Narragansett Bay in winter indicate the need to monitor coastal and offshore environments for toxins and harmful algal bloom taxa during colder months. 

Harmful and nuisance algal blooms are becoming a greater concern to public health, riverine ecosystems, and recreational uses of inland waterways. Algal bloom proliferation has increased in the Upper Clark Fork River due to a combination of warming water temperatures, naturally high phosphorus levels, and an influx of nitrogen from various sources. To improve understanding of bloom dynamics and how they affect water quality, often measured as algal biomass measured through pigment standing crops, a UAV-based hyperspectral imaging system was deployed to monitor several locations along the Upper Clark Fork River in western Montana. Image data were collected across the spectral range of 400–1000 nm with 2.1 nm spectral resolution during two field sampling campaigns in 2021. Included are methods to estimate chl a and phycocyanin standing crops using regression analysis of salient wavelength bands, before and after separating the pigments according to their growth form. Estimates of chl a and phycocyanin standing crops generated through a linear regression analysis are compared to in situ data, resulting in a maximum R2 of 0.96 for estimating fila/epip chl-a and 0.94 when estimating epiphytic phycocyanin. Estimates of pigment standing crops from total abundance, epiphytic, and the sum of filamentous and epiphytic sources are also included, resulting in a promising method for remotely estimating algal standing crops. This method addresses the shortcomings of current monitoring techniques, which are limited in spatial and temporal scale, by proposing a method for rapid collection of high-spatial-resolution pigment abundance estimates. 

Although many species shift their phenology with climate change, species vary significantly in the direction and magnitude of these responses (i.e., phenological sensitivity). Studies increasingly detect early phenology or high phenological sensitivity to climate in non-native species, which may favor non-native species over natives in warming climates. Yet relatively few studies explicitly compare phenological responses to climate between native vs. non-native species or between non-native populations in the native vs. introduced range, limiting our ability to quantify the role of phenology in invasion success. Here, we review the empirical evidence for and against differences in phenology and phenological sensitivity to climate in both native vs. non-native species and native and introduced populations of non-native species. Contrary to common assumptions, native and non-native plant species did not consistently differ in mean phenology or phenological sensitivity. However, non-native plant species were often either just as or more sensitive, but rarely less sensitive, to climate as natives. Introduced populations of non-native plant species often show earlier reproduction than native populations of the same species, but there was mixed evidence for differences in phenological sensitivity between introduced and native plant populations. We found very few studies comparing native vs. invasive animal phenology. Future work should characterize phenological sensitivity to climate in native vs. non-native plant and animal species, in native vs. introduced populations of non-native species, and across different stages of invasion, and should carefully consider how differences in phenology might promote invasion success or disadvantage native species under climate change.