The tropics as an ancient cradle of oribatid mite diversity

Leaving the tropics: The successful colonization of cold temperate regions byDolicheremaeus dorni(Acari, Oribatida)

“…Differences were either due to unresolved parts in the ML tree compared to the BI analysis (there, however, nodes were poorly supported) or in lower node supports of some taxa. In general, Parhyposomatides and Enarthronotides formed one clade at the basis of the phylogeny with Desmonomatides as sister group which is congruent with previously published data (Dabert et al, 2010; Pachl et al, 2012, 2017). Also within Desmonomatides, the topology went quite along with the morphology-based system after Norton and Behan-Pelletier (2009).…”

“…Furthermore, our results revealed similar topologies as already published phylogenies (e.g., Iseki & Karasawa, 2014; Pachl et al, 2012, 2017), aside from the different taxa and taxonomic classification used. According to the system provided by Norton and Behan-Pelletier (2009), Oppiodea and Gustavioidea might be closely related to the Carabodoidea, which in fact is supported by our phylogenetic data.…”

“…This general concept suggests that (i) species richness is higher in tropical biomes because most taxa originated in the tropics, (ii) tropic taxa had more time and area available for speciation, and (iii) species are specialized for tropical climates and only few were able to disperse out of the tropics and adapt to the cold (often freezing) temperatures of middle- and high-latitude regions. These three points are also met by the hypothesis of Pachl et al (2017) stating that the desmonomatan radiation started on the super continent Pangaea where mites were mainly exposed to tropical climatic conditions.…”

“…Despite long-standing studies, causes and/or factors for this increase in species diversity occurring from the poles to the tropics, also known as “latitudinal diversity gradient,” are still unresolved and a universally accepted explanation seems to be a challenging task for the future (Brown, 2014; Condamine, Sperling, Wahlberg, Rasplus, & Kergoat, 2012; Mittelbach et al, 2007; Rohde, 1992). So far, higher species richness in tropical regions could be detected in several groups, for example, in mammals (Rolland, Condamine, Jiguet, & Morlon, 2014), in birds (Ricklefs, 2006), in amphibians (Pyron & Wiens, 2013), in insects (Novotny et al, 2006), and, as shown recently, in oribatid mites too (Pachl et al, 2017). However, in a former study, Maraun, Schatz, and Scheu (2007) demonstrated a non-linear latitude-diversity pattern of oribatid mite species diversity as species richness increased from high latitudes to the warm temperate regions but not further to the tropics.…”

Parthenogenetic vs. sexual reproduction in oribatid mite communities

“…About 10% of the known species of oribatid mites are assumed to be obligate parthenogenetic, with more than 90% of the individuals of oribatid mite communities in some ecosystems comprising parthenogenetic species (Maraun, Fronczek , Norton and Palmer (1991) highlighted that parthenogenetic species dominate many early-derivative taxa and, rather than each being recent derivatives of an ancestral sexual lineage, most extant parthenogenetic species form part of clusters of parthenogenetic species. These taxa represent phylogenetic groups of different size, from small to speciose, indicating past parthenogenetic radiations (Heethoff, Norton, Scheu, & Maraun, 2009;Pachl et al, 2017;Schaefer, Norton, Scheu, & Maraun, 2010). Furthermore, parthenogenetic species occur in habitats "where they should not be" according to most theories, for example, in climax habitats such as old-growth forests (Huhta et al, 1986) and at low altitudes (Maraun et al, 2013).…”