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We studied spatial variation in the effects of environment and network size on species positions and roles in multiple flea–mammal networks from four biogeographic realms. We asked whether species positions (measured as species strength [SS], the degree of interaction specialization [d′], and the eigenvector centrality [C]) or the roles of fleas and their hosts in the interaction networks: (a) are repeatable/conserved within a flea or a host species; (b) vary in dependence on environmental variables and/or network size; and (c) the effects of environment and network size on species positions or roles in the networks depend on species traits. The repeatability analysis of species position indices for 441 flea and 429 host species, occurring in at least two networks, demonstrated that the repeatability of SS, d′, and C within a species was significant, although not especially high, suggesting that the indices' values were affected by local factors. The majority of flea and host species in the majority of networks demonstrated a peripheral role. A value of at least one index of species position was significantly affected by environmental variables or network size in 41 and 36, respectively, of the 52 flea and 52 host species that occurred in multiple networks. In both fleas and hosts, the occurrence of the significant effect of environment or network size on at least one index of species position, but not on a species' role in a network, was associated with some species traits. [ABSTRACT FROM AUTHOR]

We studied latitudinal patterns in the species richness (SR), the phylogenetic diversity (PD), and the functional diversity (FD) of fleas and their mammalian hosts. We asked whether these patterns in either fleas, hosts, or both 1) conform to a classical latitudinal gradient; 2) vary geographically; and 3) differ between fleas and hosts. We also asked whether the patterns of PD and FD follow those of SR. We collected data on the latitudinal distribution of 1022 flea and 900 mammal species from literature sources and calculated the SR, PD, and FD of both groups in 1° latitude bands. Then, we used broken‐stick regression models to analyse separately the latitudinal variation of 1) each diversity facet and 2) fleas and hosts in each geographic quadrant. The classical latitudinal gradient pattern was not found in either fleas or hosts across any facet of diversity or geographic quadrant, except for the PD of fleas in the southeastern quadrant and the FD of hosts in the southwestern quadrant. Latitudinal patterns of the SR, PD and FD of fleas and hosts differed substantially between geographic quadrants. Furthermore, the latitudinal distributions of flea and host SR were similar in three of four quadrants (except the northeastern quadrant), whereas the latitudinal distributions of flea and host PD were similar in the southwestern quadrant only. No similarity in flea versus host FD was revealed. The latitudinal patterns of flea and host PD and FD mostly did not follow those of their SR. We conclude that latitudinal gradients of species richness and phylogenetic and functional diversity appeared not to be universal phenomena. Instead, the latitudinal distributions of these diversity facets represent an interplay of ecological (current and past) and historical processes. For parasites, the processes acting on hosts add another layer of complexity underlying their latitudinal diversity patterns. [ABSTRACT FROM AUTHOR]

A range-wide phylogenetic/phylogeographic study of the three-toed jerboas of the genus Stylodipus is conducted using the mitochondrial cytb gene and fragments of several nuclear genes. The genus has been believed to include three species: S. telum (W Central Asia, SE Europe), S. andrewsi (E Central Asia), and S. sungorus (Dzungar basin). Our data support the dichotomy between S. andrewsi and the other taxa forming S. telum species group. Within the latter, both mtDNA and nuclear loci indicate a species-level divergence between S. telum and the S. t. birulae lineage (Zaisan depression, NE Kazakhstan), previously considered a subspecies of S. telum and here elevated to full species. S. sungorus is recovered as a close sister group to S. birulae on the basis of nuclear data but clustered with S. telum in the mitochondrial tree. The latter taxon is the most variable and includes two closely related eastern and western sublineages, separated by the Volga-Ural sands and joined by a more divergent S. t. karelini lineage (E Kazakhstan). The observed mitonuclear discordance is hypothesized to occur due to mtDNA introgression resulting from hybridization between S. sungorus and S. t. karelini, which highlights the important role of reticulations in the evolution of Dipodidae. [ABSTRACT FROM AUTHOR]