Causes of rarity in glade-endemic plants: Implications for responses to climate change

This dissertation documents the relationship between stress-adaptation and reproductive specialization in three endemic plant species: Delphinium treleasei, Echinacea paradoxa, and Scutellaria bushii) that are locally abundant but restricted to stressful habitats and their closely-related congeners: D. carolinianum, E. pallida, S. ovata, and S. parvula) that have broader habitat use, including hot, xeric habitats. In Chapter Two, I test two hypotheses concerning reproductive specialization in endemic plants and their common congeners: CC). I quantify morphological traits that are associated with stress-adaptation and reproductive specialization, pollinator behavior, and reproductive specialization. The locally abundant, habitat specialist: LAHS) species were significantly different from their CCs in vegetative traits but the direction of the differences was not consistent among genera. On the other hand, two of the three LAHS taxa had larger flowers and fewer dominant pollinators than their CCs. In Chapter 3, I examine the responses of the LAHS and CC plants to drought and high heat conditions in order to explicitly test the prediction that the LAHS species are more resistant to high-stress environments. The LAHS species were more resistant to stress, and the CC species were not. Moreover, the LAHS species had fewer, higher-quality offspring, whereas the CC species have more seeds of lower quality. In Chapter 4, I test the hypothesis that two LAHS species are poorer competitors for pollinators, as predicted by traditional theory of reproduction in rare species. The congeneric pairs did not compete for pollinators but varied in their morphological traits and reproductive success across sites. Finally, the research in Chapter 5 explores the response of two LAHS species and their CCs to regional climate change. Using herbarium specimens, I test the prediction that LAHS species that specialize on stressful habitats are less responsive to climate change in comparison to their CC. The LAHS species are responding to climate change by flowering earlier, but none of the widespread species exhibited a change in phenology with climate change. This dissertation supports a more nuanced theory of the relationship between reproductive specialization and rarity that addresses additional factors influencing rare taxa, such as stress-adaptation, and that has important implications for species\u27 responses to climate change

Genetic barriers to historical gene flow between cryptic species of alpine bumblebees revealed by comparative population genomics

Evidence is accumulating that gene flow commonly occurs between recently diverged species, despite the existence of barriers to gene flow in their genomes. However, we still know little about what regions of the genome become barriers to gene flow and how such barriers form. Here, we compare genetic differentiation across the genomes of bumblebee species living in sympatry and allopatry to reveal the potential impact of gene flow during species divergence and uncover genetic barrier loci. We first compared the genomes of the alpine bumblebee Bombus sylvicola and a previously unidentified sister species living in sympatry in the Rocky Mountains, revealing prominent islands of elevated genetic divergence in the genome that colocalize with centromeres and regions of low recombination. This same pattern is observed between the genomes of another pair of closely related species living in allopatry (B. bifarius and B. vancouverensis). Strikingly however, the genomic islands exhibit significantly elevated absolute divergence (dXY) in the sympatric, but not the allopatric, comparison indicating that they contain loci that have acted as barriers to historical gene flow in sympatry. Our results suggest that intrinsic barriers to gene flow between species may often accumulate in regions of low recombination and near centromeres through processes such as genetic hitchhiking, and that divergence in these regions is accentuated in the presence of gene flow

Fish and mussels: importance of fish for freshwater mussel conservation

Co-extinctions are increasingly recognized as one of the major processes leading to the global biodiversity crisis, but there is still limited scientific evidence on the magnitude of potential impacts and causal mechanisms responsible for the decline of affiliate (dependent) species. Freshwater mussels (Bivalvia, Unionida), one of the most threatened faunal groups on Earth, need to pass through a parasitic larval (glochidia) phase using fishes as hosts to complete their life cycle. Here, we provide a synthesis of published evidence on the fish–mussel relationship to explore possible patterns in co-extinction risk and discuss the main threats affecting this interaction. We retrieved 205 publications until December 2015, most of which were performed in North America, completed under laboratory conditions and were aimed at characterizing the life cycle and/or determining the suitable fish hosts for freshwater mussels. Mussel species were reported to infest between one and 53 fish species, with some fish families (e.g., Cyprinidae and Percidae) being used more often as hosts than others. No relationship was found between the breadth of host use and the extinction risk of freshwater mussels. Very few studies focused on threats affecting the fish–mussel relationship, a knowledge gap that may impair the application of future conservation measures. Here, we identify a variety of threats that may negatively affect fish species, document and discuss the concomitant impacts on freshwater mussels, and suggest directions for future studies.The Portuguese Foundation for Science and Technology—FCT through POPH/FSE funds supported VM, MI and MLL under grants (SFRH/BD/108298/2015), (SFRH/BPD/90088/2012), (SFRH/BD/115728/2016), respectively. KD acknowledges the support from the Czech Science Foundation (13-05872S). RS acknowledges the support of the strategic programme UID/BIA/04050/2013 (POCI-01-0145- FEDER-007569) funded by national funds through the FCT I.P. and by the ERDF through the COMPETE2020-Programa Operacional Competitividade e Internacionalização (POCI). This study was conducted as part of the project FRESHCO: Multiple implications of invasive species on Freshwater Mussel co-extinction processes, supported by FCT (contract: PTDC/AGRFOR/1627/2014)

Measuring floral resource availability for insect pollinators in temperate grasslands – a review

Abstract. 1. The relationship between pollinators and flowering plants plays a crucial role in the function of terrestrial ecosystems. Although pollinators use floral nectar and pollen as food resources, no general methodology for floral resource availability estimates exists. 2. A brief review is provided on floral resource sampling methods frequently used in pollination studies. The focus is on how representative vegetation samples are both spatially and temporally, and how these are constrained by sampling effort. 3. Field studies investigating flowering plant abundance for insect pollinators in temperate grasslands were selected. We categorised the reviewed studies according to aims, sampling units, and count variables used and provide a descriptive summary on methodology. We also searched for trade-offs between different aspects of sampling investment. 4. One hundred and fifty-eight pollination studies were reviewed. Large methodolog- ical differences were found, and vegetation sampling was presented in many studies insufficiently. Sampling covered a small proportion (median: 0.69%) of the study sites, with long intervals (median: 30 days), and most studies lasted only a few years. The most often used count variables were indirect proxies of floral resources. Negative relation- ships were found in some of the different aspects of sampling, e.g. the proportion of site covered with sampling decreased with increasing site area. 5. By tailoring sampling methods to specific research questions, research effort should be optimally allocated to obtain proper spatio-temporal resolution and data coverage. Guidelines were suggested to design sampling, e.g. to increase coverage and frequency. Further field work on optimising sampling techniques is mandatory

Decision Agriculture

In this chapter, the latest developments in the field of decision agriculture are discussed. The practice of management zones in digital agriculture is described for efficient and smart faming. Accordingly, the methodology for delineating management zones is presented. Modeling of decision support systems is explained along with discussion of the issues and challenges in this area. Moreover, the precision agriculture technology is also considered. Moreover, the chapter surveys the state of the decision agriculture technologies in the countries such as Bulgaria, Denmark, France, Israel, Malaysia, Pakistan, United Kingdom, Ukraine, and Sweden. Finally, different field factors such as GPS accuracy and crop growth are also analyzed

Rarity and reproductive biology: habitat specialists reveal a complex relationship

Understanding how species with historically fragmented populations are able to persist will provide insights into which factors may be important for the maintenance of newly fragmented populations. Plants with fragmented and isolated populations, such as habitat-specialist (HS) species, are likely less attractive to pollinators and may have adaptive traits that compensate for these distributional challenges, such as larger flowers and more specialized pollination systems. If they do not have these adaptations, HS species are predicted to have lower reproductive success and be more pollen limited than widespread species. Here, I test three predictions concerning differences in reproductive traits that are known to affect attractiveness to pollinators, pollen receipt, and reproductive success, by comparing three HS species to congeneric species with broader habitat use (HT, habitat tolerators). Two of the three HS species lend partial support to the predictions that HS species have larger floral displays and more specialized pollination systems. The third HS species did not have either of these traits but did have lower relative seedset compared to its matched HT. These results provide preliminary support for a positive relationship between habitat specificity and pollination specialization, and for the role of low fecundity in contributing to range restriction of HS species. </jats:p