Niche differentiation among clones in asexual grass thrips

Abstract

Many asexual animal populations comprise a mixture of genetically different lineages, but to what degree this genetic diversity leads to ecological differences remains often unknown. Here, we test whether genetically different clonal lineages of Aptinothrips grass thrips differ in performance on a range of plants used as hosts in natural populations. We find a clear clone‐by‐plant species interactive effect on reproductive output, meaning that clonal lineages perform differently on different plant species and thus are characterized by disparate ecological niches. This implies that local clonal diversities can be driven and maintained by frequency‐dependent selection and that resource heterogeneity can generate diverse clone assemblies.

Ecological specialization and local adaptation in sympatric sexual and asexual grass thrips species

“…The species-level generalist phenotype for A. rufus was due to a combination of very generalist clones (clone 4 and 8, Figure 2) and more specialized ones (clone 2 and 9). The latter perform best on different grass species ( Festuca rubra for clone 9 and Poa pratensis for clone 2; van der Kooi et al 2019), meaning they are characterized by different fundamental niches.…”

“…We also found that the performance of asexual A. rufus females on Festuca rubra positively correlates with the abundance of this grass species at the location the females were collected (Figure 3). This, added to geographical niche variation, suggests that different grass communities favor different clonal assemblages, as different clones perform best on different grass species (van der Kooi et al 2019, Figure 2). Asexual Aptinothrips populations are also genetically highly diverse (van der Kooi and Schwander 2014; Fontcuberta García-Cuenca et al 2016), meaning that there is a large standing pool of ecologically divergent clones available for selection to act on.…”

“…The index is then scaled to vary from 0 (extreme specialist) to 1 (extreme generalist). To compare the niche sizes between A. were generated via the same methodology as described above, for the six non-cultivated grass species (i.e., excluding wheat, T. aestivum) and with 7-14 replicates per clonal line and grass species (van der Kooi et al 2019).…”

“…Contrary to predictions, in natural grass meadows experimentally manipulated for increased and decreased grass diversity, we found that increased habitat diversity consistently favored asexual over sexual Aptinothrips species (Lavanchy et al 2016). Because different asexual clones vary in their performance on different grass hosts (van der Kooi et al 2019), we hypothesized that an increased diversity of host plants would accommodate a broader panel of clones, or, more generally, that the composition of local grass species communities would drive the composition of clone genotypes.…”

Does ecology shape geographical parthenogenesis? Evidence from the facultatively parthenogenetic stick insectMegacrania batesii

“…a "frozenniche" mechanism; Vrijenhoek 1979). Attempts to test these alternative predictions have mainly focused on study systems that are apomictic, hybrids (which are often also polyploid), or automictic parthenogens that reproduce via central fusion (Bierzychudek 1989;Oplaat and Verhoeven 2015;Van Der Kooi et al 2019;Hersh 2020). These reproductive pathways often lead to stable or even increased heterozygosity when compared to sexual relatives (Suomalainen et al 1987;Marescalchi and Scali 2003;Jaron et al 2021).…”