scholarly journals Patterns and mechanisms underlying ecoregion delineation in North American freshwater plants

2021 ◽  
Author(s):  
Janne Alahuhta ◽  
Jorge García‐Girón
Keyword(s):  
North American ◽  
North American Freshwater ◽  
Freshwater Plants

scholarly journals Patterns and mechanisms underlying ecoregion delineation in North American freshwater plants

2021 ◽  
Author(s):  
Janne Alahuhta ◽  
Jorge Garcia-Giron
Keyword(s):  
North American ◽  
Late Quaternary ◽  
Life Forms ◽  
Ice Age ◽  
Plant Life Forms ◽  
North American Freshwater ◽  
Starting Point ◽  
Internal Homogeneity ◽  
Freshwater Plants ◽  
Species Replacements

Aim: Biogeographical regionalisations are actively studied in different ecosystems, because they increase our understanding on fundamental broad-scale patterns and can help us in the establishment of conservation areas. Thus, we studied how well existing freshwater ecoregions describe geographical delineation for inland water plants and which ecogeographical gradients explain them. Location: North America, excluding Mexico and remote islands. Taxon: Freshwater vascular plants of all taxa and different functional groups. Methods: Using newly available fine-grained data on freshwater plant distributions, we calculated internal homogeneity and cross-boundary heterogeneity among neighbouring ecoregions. We further integrated measures of community dissimilarity to assess whether the degree of within-ecoregion homogeneity and distinctness are driven by their relationships to species replacements and richness differences, and explored how a complex suite of ecogeographical mechanisms and plant life forms affect ecoregion delineation using spatially explicit regression routines. Results: We found a clear geographical patterning of ecoregion robustness for North American freshwater plants, with their communities being more internally homogeneous and more similar to one another in polar and subtropical inland waters. Surprisingly, the degree of internal homogeneity and ecoregion distinctness were almost equally driven by species replacements and richness differences. Considering different life forms, ecoregion delineation performed best for emergent and floating-leaved plants. Finally, within-ecoregion homogeneity and distinctness were best explained by annual mean temperature and terrain ruggedness, respectively, with mean water alkalinity, ecoregion area and Late Quaternary Ice Age legacies having supplementary effects. Main conclusions: Our findings emphasise that geographical regionalisations founded on a particular organismal group are not applicable for all taxa. Our study is a promising starting point for further investigations of geographical delineations for different freshwater taxa. These updated regionalisations can then be used for conserving different biotas in freshwaters, which are currently among the most threatened ecosystems in the world.

Estimating thermal response metrics for North American freshwater fish using Bayesian phylogenetic regression

2018 ◽  
Vol 75 (11) ◽  
pp. 1878-1885 ◽  
Author(s):  
Sarah S. Hasnain ◽  
Michael D. Escobar ◽  
Brian J. Shuter
Keyword(s):  
Freshwater Fish ◽  
Fish Species ◽  
North American ◽  
Thermal Response ◽  
Estimation Accuracy ◽  
Freshwater Fish Species ◽  
Optimum Growth Temperature ◽  
North American Freshwater ◽  
North American Freshwater Fish ◽  
Phylogenetic Regression

Physiological performance in fish peaks within a well-defined range of temperatures, which is distinct for each species. Species-specific thermal responses for growth, survival, and reproduction are most commonly quantified directly through laboratory experiment or field observation, with a focus on six specific metrics: optimum growth temperature and final temperature preferendum (growth), upper incipient lethal temperature and critical thermal maximum (survival), and optimum spawning temperature and optimum egg development temperature (reproduction). These values remain unknown for many North American freshwater fish species. In this paper, we present a new statistical method (Bayesian phylogenetic regression) that uses relationships between these metrics and phenetic relatedness to estimate unknown metric values. The reliability of these estimates was compared with those derived from models incorporating taxonomic family and models without any taxonomic information. Overall, incorporating taxonomic family relatedness improved estimation accuracy across all metrics. For Salmonidae and Cyprinidae, estimates derived from Bayesian phylogenetic regression typically had the highest expected reliability. We used our methods to generate 274 estimates of unknown metric values for over 100 North American freshwater fish species.

Cretaceous Esocoidei (Teleostei): early radiation of the pikes in North American fresh waters

1992 ◽  
Vol 66 (5) ◽  
pp. 839-846 ◽  
Author(s):  
Mark V. H. Wilson ◽  
Donald B. Brinkman ◽  
Andrew G. Neuman
Keyword(s):  
North America ◽  
North American ◽  
New Genera ◽  
Distinctive Features ◽  
Fresh Waters ◽  
North American Freshwater ◽  
Early Radiation ◽  
Freshwater Teleosts

Contrary to ideas that Cretaceous fresh waters contained few teleosts, there were several taxa of Esocoidei (pikes and relatives) in North American Cretaceous rivers. Dentaries and palatines of Campanian to Maastrichtian age all have C-shaped tooth bases and other distinctive features of shape and foramina. The fossils include at least three distinct kinds, two of which are described here as new genera and species in the Esocidae: Estesesox foxi n. gen. and sp. and Oldmanesox canadensis n. gen. and sp.These old, diverse, and apparently primitive specimens show that pikes radiated when Eurasia and North America were still joined. Some references in the literature to the Cretaceous fish Platacodon Marsh are based on referred dentaries that are here identified as esocoid fossils. The Esocidae are the first example of a family of Recent North American freshwater teleosts that has been shown to have speciated in Cretaceous fresh waters and survived the terminal Cretaceous extinction.

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