Taxonomic scale and community organization impact observed latitudinal gradients of parasite diversity

Abstract

Aim: While most free-living taxa follow the latitudinal diversity gradient (LDG), or the trend of higher diversity at lower latitudes, we know little about how the diversity of parasitic taxa is distributed across latitudes. To better understand the macroecological patterns of parasite diversity, we sought to determine whether (1) helminths follow the traditional LDG; (2) taxonomic resolution impacts observed patterns; (3) latitudinal patterns are consistent across levels of community organization and (4) helminth diversity is correlated with climate-and host-associated variables.

Tapping into natural history collections to assess latitudinal gradients of parasite diversity

“…Furthermore, Preisser et al . ( 2022 ) focusing on Central and North America cricetid rodent assemblages found similar trends for overall helminth and nematode diversity, with further variation between the ecological scales of analysis (infracommunity vs component community). In contrast, Harris and Dunn ( 2010 ) found that diversity of parasites (including viruses, bacteria, protozoa, helminths and ectoparasites) infecting Nearctic carnivorous mammals had a mid-latitude peak.…”

“…where S est is the richness estimate (rarefaction or asymptotic), S SE is the estimated standard error of the estimate, S true is the true, unknown richness at each ecoregion and β Lat is the rate of change in diversity with latitude. As some parasite groups have been shown to display mid-latitude peaks in diversity (Janzen, 1981 ; Harris and Dunn, 2010 ; Preisser et al ., 2022 ), we also evaluated the fit of a quadratic relation between parasite richness and latitude.…”

“…Latitudinal gradients of diversity, one of the most explored and best described biogeographical patterns in free-living organisms (Willig et al ., 2003 ), still present significant challenges from a parasitological perspective. Despite considerable research in recent decades (Kamiya et al ., 2014 ; Preisser, 2019 ; Johnson and Haas, 2021 ; Martins et al ., 2021 ; Preisser et al ., 2022 ), the emergence of a general description of latitudinal variation in parasite species richness is still elusive. Currently and in the past, the detected patterns for this aspect of parasite biogeography have been dependent on the host and parasite taxa, as well as methodological approach (Preisser, 2019 ).…”

“…Most assessments of large-scale spatial variation of parasite richness have been based on reviews of available literature databases such as the Global Mammal Parasite Database (Stephens et al ., 2017 ) or the London Natural History Museum Host–Parasite database (Dallas, 2016 ) – although see Preisser et al . ( 2022 ) and Johnson and Haas ( 2021 ) for assessment based on data collected in the field specifically for this purpose. These databases provide valuable spatial/geographic information of host–parasite associations reported in thousands of papers, book chapters and other sources.…”

Gastrointestinal parasite assemblages from the wild rodent capybara (Hydrochoerus hydrochaeris) inhabiting a natural protected area from Argentina

“…This result aligns with the classical diversity gradient commonly observed in free-living species, where species richness tends to increase near the tropics and decline toward the poles. However, studies on latitudinal diversity gradients in parasitic species richness are still limited (Preisser 2019; Preisser et al 2022). Given the scarcity of research on parasite assemblages of wild species, particularly capybaras, further studies are necessary to draw comprehensive conclusions.…”