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"DISTYLY has probably arisen to promote pollen dispersal (and therefore outcrossing) and is often associated with self incompatibility. Specialization of one type for maleness and the other for femaleness may progress to full dioecy." https://lnkd.in/gb3zS32 View in LinkedIn

“HETEROSTYLY is a unique form of polymorphism and herkogamy in flowers. In a heterostylous species, two or three morphological types of flowers, termed "morphs", exist in the population. On each individual plant, all flowers share the same morph. The flower morphs differ in the lengths of the pistil and stamens, and these traits are not continuous.“ https://lnkd.in/dBgeGam View in LinkedIn

AN EXAMPLE. "One of the most interesting examples is that of the wasp pollinated dioecious figs (Ficus spp.) of tropical rain forests. The dioecious species are usually found in the understorey whereas monoecious species inhabit the canopy. The dioecious figs have clearly evolved from monoecious species but the mechanism itself is not clear." https://lnkd.in/gb3zS32 View in LinkedIn

A NUANCED ROAD. "Although monoecy is a developmental modification rather than a genetic separation as is the case for dioecy, a monoecious population could evolve into a dioecious one through a series of mutations which alter the ratio of male to female flowers." https://lnkd.in/gb3zS32 View in LinkedIn

MORE COMPLEX ROAD. "The evolution of a gynodioecious population to a dioecious one requires a second mutation, causing female sterility in hermaphrodites and generating males. There is good evidence that increased maleness in the hermaphrodites will be advantageous because of the increased availability of ovules (provided by the females)." https://lnkd.in/gb3zS32 View in LinkedIn

FITNESS GAME. "A single gene mutation or cytoplasmic male sterility system generating females (causing male sterility) will spread through a population if mutant plants are fitter than the hermaphrodites." https://lnkd.in/gb3zS32 View in LinkedIn

EXAPTED GENES. "Hermaphroditic plants may well carry genes with sequences similar to sex determining genes but they are likely to have different functions in these species, the sex determining genes (as distinct from the downstream genes which result in the organ differences) arising by gene duplication and functional divergence." https://lnkd.in/gb3zS32 View in LinkedIn

INTERMEDIATE SYSTEM. "In Rumex hastatulus, which evolved a sex chromosome system independently of R. acetosa, both X and Y chromosomes are involved in an intermediate system." https://lnkd.in/gb3zS32 View in LinkedIn

SEX CHANGE. "In Zea mays, a monoecious species, the Tasselseed (ts) loci cause the reversal of sex in tassel florets, so that pistils develop and stamen development is suppressed." https://lnkd.in/gb3zS32 View in LinkedIn

ACTUAL NUMBER. "Differentiated sex chromosomes have been established clearly in only six families, representing about eight species and two major species groups." https://lnkd.in/gb3zS32 View in LinkedIn