Phylogeographical evidence for historical long-distance dispersal in the flightless stick insect
            <i>Ramulus mikado</i>

Suetsugu, Kenji; Nozaki, Tomonari; Hirota, Shun K.; Funaki, Shoichi; Ito, Katsura; Isagi, Yuji; Suyama, Yoshihisa; Kaneko, Shingo

doi:10.1098/rspb.2023.1708

Cited by 3 publications

(1 citation statement)

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“…In Euphasmatodea, the evolution of a hardened egg chorion is a key innovation and may have contributed to the group’s extreme diversification by opening up multiple routes of unusual dispersal 30,36 . Hard shells and their associated structures can withstand hazardous falls from the forest canopy, float for extended periods of time on sea water (hydrochory) 37 , bear ant-attractive capitula (analogous to plants’ eliasomes, myrmecochory) 38 , and even survive passage through the guts of birds (endozoochory) 39,40 . Accordingly, female phasmids employ a variety of egg-laying strategies, including passively dropping or actively flicking eggs to the forest floor, burying them in soil or other soft substrates, and gluing them to plant surfaces individually, in groups, or inside complex ootheca 30,41 .…”

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confidence: 99%

Resource allocation strategies and mechanical constraints drive the diversification of stick and leaf insect eggs

Boisseau,

Woods

2023

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The diversity of insect eggs is astounding but still largely unexplained. Here, we apply phylogenetic analyses to over 210 species of stick and leaf insects (order Phasmatodea), coupled with physiological measurements of metabolic rate and water loss, to evaluate several major classes of factors that may drive egg morphological diversification: life history constraints, material costs and mechanical constraints, and ecological circumstances. We show support for all three classes, but egg size is primarily influenced by female body size and strongly trades off with egg number. Consequently, females that lay relatively fewer but larger eggs, which develop more slowly because of disproportionately low metabolic rates, tend to bury or glue them in specific locations, instead of simply dropping them from the foliage (ancestral state). This form of parental care then directly favors relatively elongated eggs, which may facilitate their specific placement and allow easier passage through the oviducts in slender species. In addition, flightless females display a higher reproductive output and consequently lay relatively more and larger eggs compared to flight-capable females. Surprisingly, local climatic conditions had only weak effects on egg traits. Overall, our results suggest that morphological diversification of stick insect eggs is driven by a complex web of causal relationships among traits, with dominant effects of resource allocation strategies and mechanical constraints.

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Section: Introductionmentioning

confidence: 99%

Resource allocation strategies and mechanical constraints drive the diversification of stick and leaf insect eggs

Boisseau,

Woods

2023

Preprint

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Fruitless mating with the exes: the irreversible parthenogenesis in a stick insect

Nozaki

Chikami

Yano

et al. 2023

Preprint

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Parthenogenetic lineages, common in many animals, have sparked debate about their evolutionary persistence. Even after the loss of male individuals, males can survive on the genomes; in fact, rarely occurring males were described in many asexual lineages. Theoretical predictions suggest that genes related to male sexual traits in parthenogenetic lineages will decay over long evolutionary times free from the pressure of stabilizing selection. However, in many cases, such rare males are potentially functional. In this study, we investigated the functionality of rare males in the Japanese parthenogenetic stick insect,Ramulus mikado. Rarely occurring males in the species exhibited the external and anatomical morphology typical in stick insect males, and vigorously and successfully performed mating behaviors with conspecific females; nevertheless, no paternal genotypes were detected in the offspring; all embryos were genetically identical to their mothers. Our histological observation demonstrated that females received a spermatophore without sperms in their copulatory pouch, and revealed that in a male, spermatogenesis was completely deformed. These results suggest the irreversible clonal reproduction ofR. mikadodue to compromised male function. Our present study provides the first case of evident dysfunction in rare males of stick insects, illuminating the degenerative evolution of sexual traits in asexual lineages.

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Population genetics of the freshwater red alga Batrachospermum gelatinosum (Rhodophyta) II: Phylogeographic analyses reveal spatial genetic structure among and within five major drainage basins in eastern North America

Crowell,

Shainker‐Connelly,

Krueger‐Hadfield

et al. 2024

Journal of Phycology

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The freshwater red alga Batrachospermum gelatinosum has a well‐documented distribution spanning historically glaciated and unglaciated eastern North America. This alga has no known desiccation‐resistant propagule; thus, long‐distance dispersal events are likely rare. We predicted strong genetic structure among drainage basins and admixture among sites within basins. We predicted greater genetic diversity at lower latitude sites because they likely serve as refugia and the origin of northward, post‐Pleistocene range expansion. We used 10 microsatellite loci to investigate genetic diversity from 311 gametophytes from 18 sites in five major drainage basins: South Atlantic Gulf, Mid‐Atlantic, Ohio River, Great Lakes, and Northeast. Our data showed strong genetic partitioning among drainage basins and among sites within basins, yet no isolation by distance was detected. Genetic diversity varied widely among sites and was not strictly related to latitude as predicted. The results from B. gelatinosum provide strong support that each stream site contributes to the unique genetic variation within the species, potentially due to limited dispersal and the prevailing reproductive mode of intragametophytic selfing. Simulations of migration suggested post‐Pleistocene dispersal from the Mid‐Atlantic. Batrachospermum gelatinosum potentially persisted in refugia that were just south of the ice margins rather than in the southernmost part of its range. Research of other taxa with similar ranges could determine whether these results are generally applicable for freshwater red algae. Nevertheless, these results from B. gelatinosum add to the growing literature focused on the patterns and genetic consequences of post‐Pleistocene range expansion by eastern North American biota.

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Phylogeographical evidence for historical long-distance dispersal in the flightless stick insect Ramulus mikado

Cited by 3 publications

References 86 publications

Resource allocation strategies and mechanical constraints drive the diversification of stick and leaf insect eggs

Resource allocation strategies and mechanical constraints drive the diversification of stick and leaf insect eggs

Fruitless mating with the exes: the irreversible parthenogenesis in a stick insect

Population genetics of the freshwater red alga Batrachospermum gelatinosum (Rhodophyta) II: Phylogeographic analyses reveal spatial genetic structure among and within five major drainage basins in eastern North America

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