Female sterility in Ulmus minor (Ulmaceae): a hypothesis invoking the cost of sex in a clonal plant

Abstract

A high incidence of individuals with low seed set was found in two populations of the field elm Ulmus minor, a European tree that reproduces sexually and via vegetative propagation through root sprouting. One population was a seminatural stand, while the other was established by artificial propagation of genotypes sampled widely across Spain. The low seed set in both populations was due to both pre- and post-zygotic factors, the importance of which vary between genotypes. These factors included gynoecial malformations that produced a non-ovulated pistil, early gynoecial necrosis (i.e., necrosis before any opportunities for pollination), and seed abortion. Female sterility gave rise to two classes of individuals: trees that were largely female-sterile but dispersed normal quantities of viable pollen, and trees that dispersed both normal pollen and substantial numbers of seeds. Reduced production of protein-rich seeds may increase the resource availability for clonal propagation, helping to maintain female-sterile individuals with hermaphrodites.

Genetic variation and heritability estimates of Ulmus minor and Ulmus pumila hybrids for budburst, growth and tolerance to Ophiostoma novo-ulmi

“…If we had observed a wider range of wilt symptoms, the genetic variability would have been readily expressed and the heritability values would probably have been higher (Strong et al 1993, Le Cocq et al 2005. We acknowledge that the number of replicates should have been higher, but unfortunately some clones used for the diallel design, coded CC-VG2, M-IN5 and V-JR1 and later characterized as female-sterile trees (López-Almansa et al 2003, provided no seeds.…”

Nitrogen addition and rhizome severing modify clonal growth and reproductive modes of Leymus chinensis population

“…For clonal plants, sexual versus clonal reproductive trade-off is of great significance in terms of ecology and evolution. In general, clonal plants rely more on clonal reproduction under favorable conditions (N addition treatment in the present study for an example) than under unfavorable ones, probably because the sexual reproduction is much more costly than clonal reproduction (López-Almansa et al 2003). The favorable environment reduces the needs for progeny genetic diversity to be selected.…”

Historical, ecological, taxonomic and health characterization of the relict elm stand of Rivas-Vaciamadrid (Madrid)

“…Como consecuencia de todo ello, los pies funcionalmente masculinos pueden reproducirse exclusivamente a través del polen, frente a los pies cosexuales que se reproducen tanto a través del polen como de la producción de semilla. (López-Almansa et al, 2003). Los estudios genéti-cos realizados con posterioridad (ver más adelante) han mostrado que estos pies masculinos pertenecen a única-mente dos clones estrechamente relacionados, que se encuadran dentro de Ulmus minor var.…”

“…Esto sugiere que la propagación en la zona central ha sido fundamentalmente por vía vegetativa, mientras que en los márgenes la regeneración ha tenido su origen principalmente en semillas que, probablemente, han llegado allí con posterioridad arrastradas por el viento o el agua. Apoya esta hipótesis el hecho de que en la olmeda se observa que los pies abortantes son significativamente más altos (21,50 ± 0,42 m; media ± DE) que los individuos cosexuales (16,04 ± 0,81 m) (P < 0,001) y que presentan un crecimiento diametral mayor (5,1 ± 0,4 y 3,2 ± 0,6 mm/año, respectivamente; P < 0,05) (Tabla 1), lo que sugiere que los pies abortantes pueden destinar una mayor inversión en crecimiento vegetativo que los cosexuales (López-Almansa et al, 2003).…”

“…En este trabajo se presentan, revisan y discuten conjuntamente los resultados de una serie de investigaciones iniciadas en el año 2000, que contemplan el estudio de la evolución de la olmeda durante los últimos años, la caracterización ecológica y taxonómica de su población, y la evaluación del estado fitosanitario (Cabrera, 2001;Fuentes-Utrilla, 2002;López-Almansa 2002;Dacasa et al, 2003;López-Almansa et al, 2003;Martín y Gil, 2003;Gil et al, 2004;Solla et al 2006).…”