Pieter T. J. Johnson's research while affiliated with University of Colorado Boulder and other places

... This study site has been an area of active alpine research and data collection for the last ~70 years, and is one of the most 50 intensively studied alpine ecosystems in the world (Bjarke et al., 2021). The datasets were collected approximately weekly from late-June 2017 through mid-August 2017, comprising the period of summer snowmelt and vegetation growth. ...

... Therefore, greater biodiversity is expected near the equator and a gradual decrease with distance from the tropics (Schemske et al. 2009). For parasites, studies show non-existent, inverse, or positive patterns regarding richness and abundance as a function of latitude (Rohde and Heap 1998;Sellers et al. 2015;Johnson and Haas 2021). ...

... This difference among genotypes in transgenerational impacts strongly resembles the variation shown by Drosophila genotypes in transgenerational responses to environmental stressors (31). These differences have the potential to scale up to host population-level differences in the ability to 15 compensate for transgenerational virulence driven increases in mortality (32), with potential implications for host population genetic composition and infection prevalenceproviding further evidence of the importance of considering host life history in disease ecology (33). ...

... Close association between host and parasite populations over extended periods of time results in antagonistic coevolution (Schmid Hempel, 2011). Because parasites typically have fast generation times and high effective population sizes, they may evolve faster than their hosts, thereby maintaining an advantage in the coevolutionary arms race (Johnson et al., 2021). As a result, parasites are expected to achieve greater fitness from interactions with sympatric hosts than with allopatric hosts. ...

... The environmental contamination by this parasite also depends on the size of the population of the intermediate and definitive hosts [48]. Despite many studies on the impact of factors affecting the spread of T. gondii, the mechanisms related to the promotion of the pathogen in the environment are still not fully known [49]. Wild rodents are frequent prey of predators, including felid species. ...

... In recent times, study on the infection and prevalence of parasitic isopods on commercial fishes were reported from Paranagipettai coast, India (Bharadhirajan et al. 2014), Malabar Coast, India (Aneesh et al. 2016;Rijin et al. 2017), Mirri, East Malaysia (Anand Kumar et al. 2015Kumar et al. , 2017, Atlantic menhaden (Rose et al. 2020) and other parts of the globe as well. However, before the present report, no such comprehensive study based on the infection of parasitic isopods on the commercial fishes of NPECI was reported. ...

... [3][4][5][6]) and ecological (e.g. [7][8][9][10][11][12]) aspects of the occurrence and diversity of digenean larval stages in leeches. Moreover, contemporary understanding of the diversity of Strigeidae trematodes has been significantly changed by the recently discovered high level of interspecific and intergeneric homogeneity of morphological features related to an unexpectedly high level of genetic diversity, revealed within the genera Australapatemon and Cotylurus [13][14][15][16]. ...

... Pre-transmission mortality also explained variation in competence (but this relationship was weaker than that for barrier resistance). This form of parasite loss is often overlooked or unreported and can be especially challenging to observe in field studies (Wilber et al., 2020). But quantifying this attribute is critical, as it can explain a species' low transmission potential. ...

... For example, van Leeuwen et al. (2013) demonstrated high rates of genetic interchange for Spanish populations of the alien aquatic snail Physella acuta, for which waterbird endozoochory has since been confirmed (Martín-Vélez et al., 2022). Martin et al. (2020) found that the population structure of the gastropod Planorbella trivolvis suggested LDD along a migratory flyway. Likewise, variation in mitochondrial clades of brine shrimp Artemia franciscana across the Americas is related to shorebird flyways (Muñoz et al., 2013). ...

... Answers to this enduring question shape public health decisions, disease management, pest control, and food safety. Given that pathogens and parasites are ubiquitous and critical components of natural ecosystems, deciphering these feedbacks may also yield new insight into fundamental biological processes critical to conservation such as mate choice (Nuismer et al. 2008;Ashby and Boots 2015), diversity (Hall et al. 2011;Wood et al. 2020), stability (Hilker and Schmitz 2008;Hite and Cressler 2018), and sex (Lively 1996;Morran et al. 2011). Yet, while the clear interdependence between ecological and evolutionary dynamics are well-recognized, understanding their relative contributions and mechanistic underpinnings remains challenging (Hendry 2019). ...