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PreprintTwo families of non-LTR retrotransposons, Syrinx and Daphne, from the Darwinulid ostracod, Darwinula stevensoni( 2005-12-15) Schon, Isabelle ; Arkhipova, Irina R.Two novel families of non-LTR retrotransposons, named Syrinx and Daphne, were cloned and characterized in a putative ancient asexual ostracod Darwinula stevensoni. Phylogenetic analysis reveals that Daphne is the founding member of a novel clade of non-LTR retroelements, which also contains newly described families from the sea urchin and the silkworm and forms a sister clade to L2-like elements. The Syrinx family of non-LTR retrotransposons exhibits evidence of relatively recent activity, manifested in high levels of sequence similarity between individual copies and a three- to ten-fold excess of synonymous substitutions, which is indicative of purifying selection. The Daphne family may have very few copies with intact open reading frames, and exhibits neutral within-family ratio of non-synonymous to synonymous substitutions. It can additionally be characterized by formation of inverted truncated head-to-head structures. All of these features make recent activity less likely than in the Syrinx family. Our results are discussed in light of the evolutionary consequences of long-term asexuality in general and in Darwinula stevensoni in particular.
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ArticleThe common morphospecies Cypridopsis vidua (O.F. MÜLLER, 1776) (Crustacea, Ostracoda) is not an obligate parthenogen(Royal Belgian Zoology Society, 2023-01-19) Martens, Koen ; Shribak, Michael ; Arkhipova, Irina ; Schön, IsaThe common non-marine ostracod Cypridopsis vidua (O.F. Müller, 1776) is used as a proxy in various biological disciplines, such as (palaeo-)ecology, evolutionary biology, ecotoxicology and parasitology. This morphospecies was considered to be an obligate parthenogen. We report on the discovery of the first population of C. vidua with males from Woods Hole (MA, USA) and determine that it is a population with mixed reproduction. We describe the morphology of the males and of the sexual and asexual females. We illustrate a copula of a male and a sexual female as well insemination in a sexual female, showing that males are functional. Therefore, Cypridopsis vidua is a morphospecies with mixed reproduction, not a full apomictic parthenogen. We use, for the first time, polychromatic polarization microscope technology to illustrate soft parts of ostracods. In addition, we compare the sexual species C. bisexualis, C. okeechobei, C. howei and C. schwartzi and conclude that these species, especially the latter three, are morphologically very close to C. vidua.