Male fertility advantage within and between seasons in the perennial androdioecious plant Phillyrea angustifolia.

Background And Aims: Androdioecy, the co-occurrence of males and hermaphrodites, is a rare reproductive system. Males can be maintained if they benefit from a higher male fitness than hermaphrodites, referred to as male advantage. Male advantage can emerge from increased fertility owing to resource reallocation.

Evidence for the long-term maintenance of a rare self-incompatibility system in Oleaceae.

A rare homomorphic diallelic self-incompatibility (DSI) system discovered in Phillyrea angustifolia (family Oleaceae, subtribe Oleinae) can promote the transition from hermaphroditism to androdioecy. If widespread and stable in Oleaceae, DSI may explain the exceptionally high rate of androdioecious species reported in this plant family. Here, we set out to determine whether DSI occurs in another Oleaceae lineage.

Selfish male-determining element favors the transition from hermaphroditism to androdioecy.

According to the current, widely accepted paradigm, the evolutionary transition from hermaphroditism toward separate sexes occurs in two successive steps: an initial, intermediate step in which unisexual individuals, male or female, sterility mutants coexist with hermaphrodites and a final step that definitively establishes dioecy. Two nonexclusive processes can drive this transition: inbreeding avoidance and reallocation of resources from one sexual function to the other. Here, we report results of controlled crosses between males and hermaphrodites in Phillyrea angustifolia, an androdioecious species with two mutually intercompatible, but intraincompatible groups of hermaphrodites.

A one-locus model of androdioecy with two homomorphic self-incompatibility groups: expected vs. observed male frequencies.

Androdioecy, the occurrence of males and hermaphrodites in a single population, is a rare breeding system because the conditions for maintenance of males are restrictive. In the androdioecious shrub Phillyrea angustifolia, high male frequencies are observed in some populations. The species has a sporophytic self-incompatibility (SI) system with two self-incompatibility groups, which ensures that two groups of hermaphrodites can each mate only with the other group, whereas males can fertilize hermaphrodites of both groups.

A self-incompatibility system explains high male frequencies in an androdioecious plant.

Androdioecy is a sexual system in which males co-occur with hermaphrodites, which have both male and female function. Stable androdioecy is rare in nature, and theory suggests that it requires that males sire more than twice as many offspring as hermaphrodites. In several members of the olive family (Oleaceae), androdioecy occurs with higher frequencies of males than predicted by theory.

High male reproductive success of hermaphrodites in the androdioecious Phillyrea angustifolia.

Androdioecy, the coexistence of males and hermaphrodites within a population, is a rare breeding system, often considered as unlikely to evolve because of restrictive conditions for its maintenance. Phillyrea angustifolia, a wind-pollinated shrub, is one of the handful species reported to be androdioecious. Our previous studies have shown that natural populations of this species in southern France exhibit higher male frequencies (approximately 50%) than predicted on theoretical grounds.

Inbreeding depression under intraspecific competition in a highly outcrossing population of Crepis sancta (Asteraceae): evidence for frequency-dependent variation.

Inbreeding depression is a major selective factor acting to maintain outcrossing in hermaphroditic plants. Recently it has been shown that environmental conditions may greatly affect the levels of inbreeding depression. In this study, the effects of intraspecific competition, from either crossed or inbred progeny, and plant density on the expression of inbreeding depression were estimated for the allogamous colonizing plant Crepis sancta (Asteraceae).

Self-Incompatibility and Male Fertilization Success in Phillyrea angustifolia (Oleaceae).

Androdioecy is a rare breeding system in which low male frequency is expected in populations because males require a strong increase in their fertility to be maintained by selection. Phillyrea angustifolia L. has previously been reported as possibly functionally androdioecious.

Zinc and cadmium hyperaccumulation by Thlaspi caerulescens from metalliferous and nonmetalliferous sites in the Mediterranean area: implications for phytoremediation.

Growth, tolerance and zinc and cadmium hyperaccumulation of Thlaspi caerulescens populations from three metal contaminated soils and three normal soils were compared under controlled conditions. Individuals of six populations were cultivated on five soils with increasing concentrations of zinc (50-25000 μg g ) and cadmium (1-170 μg g ). There was no mortality of normal soil populations in the four metal-contaminated soils, but plant growth was reduced to half that of populations from metal-contaminated soils.

Effects of simulated herbivory in three old field Compositae with different inflorescence architectures.

The effects of simulated herbivory (early or late defoliation and cutting of the flowering shoot) on the growth and reproduction of three species of monocarpic composite forbs (Crepis pulchra, Picris hieracioides and C. foetida) with different inflorescence architectures were studied in experimental plots. For the three species studied, early defoliation had no significant effect on subsequent growth.

Continuous basal sprouting from a lignotuber:Arbutus unedo L. andErica arborea L., as woody Mediterranean examples.

The two dominant species of the Corsican mattoral,Arbutus unedo L. andErica arborea L., can produce abundant sprouts from the lignotuber not only immediately after fire but also more or less continuously in the absence of major disturbance.

[Numerical cladistics of the phylogeny of the genus Leishmania Ross, 1903 (Kinetoplastida-Trypanosomatidae). Use of enzyme characteristics].

Numerical cladistics is applied to the phyletic analysis of the genus Leishmania Ross, 1903. 128 Old World stocks are characterized by means of electrophoretic techniques using 13 enzymes. The 68 electromorphs detected allow to group the stocks into 17 zymodemes.

[The application of a numerical method to the taxonomy of the genus Leishmania Ross, 1903,--The recognition of 146 original lines in the Old World. Use of allozymic characters. Epidemiological and phyletic significance (author's transl)].

Using enzyme characters determined by starch gel electrophoresis, the authors have applied the method of Numerical Taxonomy to the genus Leishmania Ross, 1903. Eight isoenzymes (PGI, ME, PGM, GOT, G-6-PDH, 6-PGDH, MDH and IDH) of 146 Old World strains are examined. 35 electromorphs, corresponding to equivalent number of isoenzymes, are identified by this method, and then grouped into 14 zymodemes.