Pseudogamy
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{{Short description, Aspect of reproduction in zoology and botany Pseudogamy refers to aspects of reproduction. It has different (but related) meanings in
zoology Zoology ( , ) is the scientific study of animals. Its studies include the anatomy, structure, embryology, Biological classification, classification, Ethology, habits, and distribution of all animals, both living and extinction, extinct, and ...
and in
botany Botany, also called plant science, is the branch of natural science and biology studying plants, especially Plant anatomy, their anatomy, Plant taxonomy, taxonomy, and Plant ecology, ecology. A botanist or plant scientist is a scientist who s ...
.


In zoology

In zoology, it means a type of
parthenogenesis Parthenogenesis (; from the Greek + ) is a natural form of asexual reproduction in which the embryo develops directly from an egg without need for fertilization. In animals, parthenogenesis means the development of an embryo from an unfertiliz ...
in which the sperm stimulates the
egg cell The egg cell or ovum (: ova) is the female Reproduction, reproductive cell, or gamete, in most anisogamous organisms (organisms that reproduce sexually with a larger, female gamete and a smaller, male one). The term is used when the female game ...
to develop into an
embryo An embryo ( ) is the initial stage of development for a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male sp ...
, but no genes from the male are inherited. Gynogenesis is a synonym.


In botany

In botany, "pseudogamy" is also related to
asexual reproduction Asexual reproduction is a type of reproduction that does not involve the fusion of gametes or change in the number of chromosomes. The offspring that arise by asexual reproduction from either unicellular or multicellular organisms inherit the f ...
.
Wilhelm Olbers Focke Wilhelm Olbers Focke (5 April 1834, Bremen – 29 September 1922, Bremen) was a medical doctor and botanist who in 1881 published a significant work on plant breeding entitled ''Die Pflanzen-Mischlinge, Ein Beitrag zur Biologie der Gewächse'' (T ...
(1881) is usually cited for the definition of the term. What he actually said was (page 525, translated) :"III PSEUDOGAMY.
In experiments to raise hybrids, you sometimes get plants that resemble the mother plant, but partly in their sexual potency appear noticeably weakened. They have for this reason often been taken for hybrids. I suspect that in such cases the foreign pollen no real fertilization completed, but only gave the stimulus to produce the outer parts of fruit. The seeds, which are found in the fruit, are, in my opinion, not spawned by hybridization and generally not through sexual procreation, rather they are incurred parthenogenetically." Thus in botany, ''pseudogamy'' means any reproductive process that requires
pollination Pollination is the transfer of pollen from an anther of a plant to the stigma (botany), stigma of a plant, later enabling fertilisation and the production of seeds. Pollinating agents can be animals such as insects, for example bees, beetles or bu ...
but does not involve male inheritance. It is sometimes used in a restrictive senseNygren, A. 1967. Apomixis in the angiosperms. In Handbuch der Pflanzenphysiologie. Edited by W. Ruhland. Springer-Verlag, Berlin. pp. 551–596.Nogler, G.A. 1984. Gametophytic apomixis. In Embryology of angiosperms. Edited by B.M. Johri. Springer, Berlin, Germany. pp. 475–518. to refer to types of agamospermy in which the
endosperm The endosperm is a tissue produced inside the seeds of most of the flowering plants following double fertilization. It is triploid (meaning three chromosome sets per nucleus) in most species, which may be auxin-driven. It surrounds the Embryo#Pla ...
is fertilized but the embryo is not (see Pseudogamous apomixis, below). A better term for the restrictive sense is centrogamy.


Pseudogamous apomixis

Apomixis In botany, apomixis is asexual development of seed or embryo without fertilization. However, other definitions include replacement of the seed by a plantlet or replacement of the flower by bulbils. Apomictically produced offspring are geneti ...
in flowering plants (
angiosperms Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (). The term angiosperm is derived from the Greek words (; 'container, vessel') and (; 'seed'), meaning that the seeds are enclosed within a fruit. T ...
) includes some types of vegetative reproduction and also agamospermy, which is asexual reproduction through seeds (see
apomixis In botany, apomixis is asexual development of seed or embryo without fertilization. However, other definitions include replacement of the seed by a plantlet or replacement of the flower by bulbils. Apomictically produced offspring are geneti ...
for more information). Agamospermy can occur through many different mechanisms, some of which require pollination (pseudogamy), and some of which do not (autonomous apomixis). Many flowering plants with pseudogamous apomixis require fertilization to produce the
endosperm The endosperm is a tissue produced inside the seeds of most of the flowering plants following double fertilization. It is triploid (meaning three chromosome sets per nucleus) in most species, which may be auxin-driven. It surrounds the Embryo#Pla ...
of the
seed In botany, a seed is a plant structure containing an embryo and stored nutrients in a protective coat called a ''testa''. More generally, the term "seed" means anything that can be Sowing, sown, which may include seed and husk or tuber. Seeds ...
. However, it has been shownBicknell, R.A., et al. (2003). Quantification of progeny classes in two facultatively apomictic accessions of Hieracium. ''Hereditas''. 138(1): 11–20. that pollination with compatible pollen can be required even in some species where endosperm development is autonomous. Pseudogamous apomixis occurs in many
families Family (from ) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictability, structure, and safety as ...
. It is particularly common in
Rosaceae Rosaceae (), the rose family, is a family of flowering plants that includes 4,828 known species in 91 genera. The name is derived from the type genus '' Rosa''. The family includes herbs, shrubs, and trees. Most species are deciduous, but som ...
and
Poaceae Poaceae ( ), also called Gramineae ( ), is a large and nearly ubiquitous family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos, the grasses of natural grassland and species cultivate ...
, where it occurs in many different
genera Genus (; : genera ) is a taxonomic rank above species and below family as used in the biological classification of living and fossil organisms as well as viruses. In binomial nomenclature, the genus name forms the first part of the binomial s ...
and
species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...
. Examples of species with pseudogamous apomixis include the Himalayan blackberry '' Rubus armeniacus'' and gamagrass '' Tripsacum dactyloides''. By contrast, autonomous apomixis is the rule among the many apomictic species of
Asteraceae Asteraceae () is a large family (biology), family of flowering plants that consists of over 32,000 known species in over 1,900 genera within the Order (biology), order Asterales. The number of species in Asteraceae is rivaled only by the Orchi ...
including the common dandelion ''
Taraxacum officinale ''Taraxacum officinale'', the dandelion or common dandelion, is a herbaceous perennial flowering plant in the daisy family, Asteraceae. The common dandelion is well known for its yellow flower heads that turn into round balls of many silver-tuf ...
'', and also occurs in several genera of
Poaceae Poaceae ( ), also called Gramineae ( ), is a large and nearly ubiquitous family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos, the grasses of natural grassland and species cultivate ...
.


References

Plant reproduction Insect reproduction Asexual reproduction Vertebrate parthenogenesis