Premeiotic endomitosis and the costs and benefits of asexual reproduction

Abstract

Different patterns of development can influence the strength and direction of selection of a trait. Here, it is shown how this may be the case for asexual reproduction in which eggs (animals) or spores (plants) inherit the maternal chromosome number through a precursor cell undergoing an endoduplication of its chromosomes prior to meiotic reduction. Asexuality involving premeiotic endoduplication (APE) has a wide but uneven distribution among animals and plants. It is argued that different patterns of egg and spore production and differences in when endoduplication occurs, together with differences in breeding structure (dioecious vs. hermaphroditic) and reproductive strategy (e.g. spawning vs. vivipary), can result in APE being associated with fecundity costs that can result in an overall cost of sex or in an overall cost of asex or in APE being selectively neutral relative to sex. There is a lack of a close correlation between the taxonomic distribution of APE and its potential costs and benefits however, possible causes of which are explored.

A drought‐driven model for the evolution of obligate apomixis in ferns: evidence from pellaeids (Pteridaceae)

“…Leveraging a synthesis of previous studies, we elaborate a multi‐pronged model for the evolution and establishment of this reproductive approach. We focus on apomixis by premeiotic endomitosis (PE, Grusz, 2016; APE, Mogie, 2013) because existing data indicate that it is, by far, the most widespread pathway to sporogenesis undertaken in apomictic ferns. During PE, an incomplete mitotic cell division produces spore mother cells with twice the sporophyte chromosome number, ultimately giving rise to unreduced spores ( n = 2 n ).…”

“…Braithwaite (1964) recognized genetic control of asynapsis during meiotic first division restitution (i.e., Braithwaite sporogenesis), consistent with observations by others (e.g., Mehra and Singh, 1957; Morzenti, 1967). Asexuality via PE (i.e., meiotic obligate apogamy or APE; Mogie, 2013) is also demonstrably heritable as a dominant trait in ferns (e.g., Morzenti, 1966; Walker, 1985; Gabancho et al, 2010). Given its dominance and the remarkable stability PE affords to sporogenesis, it is not surprising that this is the most frequently followed route to USP.…”

Geographical Parthenogenesis in Alpine and Arctic Plants

“…Classical theories emphasize the advantages of asexuality per se, such as the advantage of uniparental reproduction for colonization as single individuals can act as founders of populations, a principle known as “Bakers’ law” [ 18 ]. Other authors stressed interactions of cytotypes and postulated introgression of asexuality into sexual populations, resulting in the reduction or extinction of the latter [ 19 , 20 ]. A set of ecological theories regard the interplay of niche occupation and the population genetic structure of asexuals: Asexual hybrids could have advantages as general-purpose genotypes (GPG) that can survive in several niches [ 21 ], or by producing broad arrays of clonal lineages that would better explore the resource space than sexual species (Frozen Niche Variation model, FNV, [ 22 , 23 ]).…”

The Maintenance of Sex and David Lack's Principle

“…Yet what else should we do if we wished to understand why they are rare? Where Neiman (2004) and West-Eberhard (2005) already worked out physiological consequences, Dagg (2006) sociobiological ones, Kono (2006), Lushai & Loxdale (2007), Gorelick & Carpione (2009) epigenetic ones, and Mogie (2013) a cytological one, the following proposes a life-history constraint.…”