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80-571: Many; see § Genera Lauraceae , or the laurels , is a plant family that includes the true laurel and its closest relatives. This family comprises about 2850 known species in about 45 genera worldwide. They are dicotyledons , and occur mainly in warm temperate and tropical regions, especially Southeast Asia and South America . Many are aromatic evergreen trees or shrubs, but some, such as Sassafras , are deciduous , or include both deciduous and evergreen trees and shrubs, especially in tropical and temperate climates. The genus Cassytha

160-485: A flower or between flowers on an inflorescence . Within-flower interference, which occurs when either the pistil interrupts pollen removal or the anthers prevent pollen deposition, can result in autonomous or facilitated self-pollination. Between-flower interference results from similar mechanisms, except that the interfering structures occur on different flowers within the same inflorescence and it requires pollinator activity. This results in geitonogamous pollination,

240-410: A biological event concerns the molecular and physiological mechanisms that produce the event. Many studies have focused on the proximate causes of sequential hermaphroditism, which may be caused by various hormonal and enzyme changes in organisms. The role of aromatase has been widely studied in this area. Aromatase is an enzyme that controls the androgen / estrogen ratio in animals by catalyzing

320-424: A biological event determines how the event makes organisms better adapted to their environment, and thus why evolution by natural selection has produced that event. While a large number of ultimate causes of hermaphroditism have been proposed, the two causes most relevant to sequential hermaphroditism are the size-advantage model and protection against inbreeding. The size-advantage model states that individuals of

400-442: A brilliant terminal-phase coloration, which has a change in intensity of color, stripes, and bars. Terminal-phase coloration occurs when males become large enough to defend territory. Initial-phase males have larger testes than larger, terminal phase males, which enables the initial-phase males to produce a large amount of sperm. This strategy allows these males to compete with the larger territorial male. Botryllus schlosseri ,

480-453: A certain size. In most ectotherms , body size and female fecundity are positively correlated. This supports the size-advantage model. Kazancioglu and Alonzo (2010) performed the first comparative analysis of sex change in Labridae . Their analysis supports the size-advantage model and suggest that sequential hermaphroditism is correlated to the size-advantage. They determined that dioecy

560-410: A colonial tunicate , is a protogynous hermaphrodite. In a colony, eggs are released about two days before the peak of sperm emission. Although self-fertilization is avoided and cross-fertilization favored by this strategy, self-fertilization is still possible. Self-fertilized eggs develop with a substantially higher frequency of anomalies during cleavage than cross-fertilized eggs (23% vs. 1.6%). Also

640-805: A generous layer of wax , making them glossy in appearance, and a narrow, pointed-oval shape with a 'drip tip', which permits the leaves to shed water despite the humidity, allowing transpiration to continue. Scientific names similar to Daphne (e.g., Daphnidium , Daphniphyllum ) or "laurel" (e.g., Laureliopsis , Skimmia laureola ) indicate other plant families that resemble Lauraceae. Some Lauraceae species have adapted to demanding conditions in semiarid climates, but they tend to depend on favorable edaphic conditions, for example, perennial aquifers, periodic groundwater flows, or periodically flooded forests in sand that contains hardly any nutrients. Various species have adapted to swampy conditions by growing pneumatophores , roots that grow upward, that project above

720-491: A given sex reproduce more effectively if they are a certain size or age. To create selection for sequential hermaphroditism, small individuals must have higher reproductive fitness as one sex and larger individuals must have higher reproductive fitness as the opposite sex. For example, eggs are larger than sperm, thus larger individuals are able to make more eggs, so individuals could maximize their reproductive potential by beginning life as male and then turning female upon achieving

800-410: A harem"). In a paired mating system (one male mates with one female, such as in clownfish or moray eels) the male can only fertilize one batch of eggs, whereas the female needs only a small male to fertilize her batch of eggs. so the larger she is, the more eggs she'll be able to produce and have fertilized. Therefore, in this kind of paired mating system, protandry is the most adaptive strategy ("breed as

880-413: A haremic mating system, with one large male controlling access to numerous females for mating, this large male achieves greater reprodcutive success than a small female as he can fertilize numerous baches of eggs. So in this kind of haremic mating system (such as many wrasses), protogyny is the most adaptive strategy ("breed as a female when small, and then change to male when you're large and able to control

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960-554: A lack of widespread consensus within the scientific community for extended periods. The continual publication of new data and diverse opinions plays a crucial role in facilitating adjustments and ultimately reaching a consensus over time. The naming of families is codified by various international bodies using the following suffixes: The taxonomic term familia was first used by French botanist Pierre Magnol in his Prodromus historiae generalis plantarum, in quo familiae plantarum per tabulas disponuntur (1689) where he called

1040-458: A male when small, and then change to female when you're larger"). Sequential hermaphroditism can also protect against inbreeding in populations of organisms that have low enough motility and/or are sparsely distributed enough that there is a considerable risk of siblings encountering each other after reaching sexual maturity, and interbreeding. If siblings are all the same or similar ages, and if they all begin life as one sex and then transition to

1120-414: A more general mechanism for reducing the impact of pollen - pistil interference on pollen import and export. Unlike the inbreeding avoidance hypothesis, which focused on female function, this interference-avoidance hypothesis considers both reproductive functions. In many hermaphroditic plant species, the close physical proximity of anthers and stigma makes interference unavoidable, either within

1200-410: A nonsexual juvenile plant, to a young all-male plant, to a male-and-female plant, to an all-female plant. This means that A. triphyllum is changing its sex from male to female over the course of its lifetime as its size increases, showcasing Size Dependent Sex Allocation. Another example is Arisaema dracontium or the green dragon, which can change its sex on a yearly basis. The sex of A. dracontium

1280-753: A period of several years, and are sequential hermaphrodites. When branches were removed from striped maple trees they changed to female or to female and male as a response to the damage. Sickness will also trigger a sex change to either female or female and male. In the context of the sexuality of flowering plants (angiosperms), there are two forms of dichogamy: protogyny —female function precedes male function—and protandry —male function precedes female function. Examples include in Asteraceae , bisexual tubular (disks) florets are usually protandrous. Whereas in Acacia and Banksia flowers are protogynous, with

1360-405: A severe reproductive disadvantage, which promotes strong selection of size-based protogyny. Therefore, if an individual is small, it is more reproductively advantageous to be female because they will still be able to reproduce, unlike small males. Common model organisms for this type of sequential hermaphroditism are wrasses . They are one of the largest families of coral reef fish and belong to

1440-507: A sex ratio biased towards the birth sex, and consequently experience significantly more reproductive success after switching sexes. According to the population genetics theory, this should decrease genetic diversity and effective population size (Ne). However, a study of two ecologically similar santer sea bream ( gonochoric ) and slinger sea bream (protogynous) in South African waters found that genetic diversities were similar in

1520-455: A significantly lower percentage of larvae derived from self-fertilized eggs metamorphose, and the growth of the colonies derived from their metamorphosis is significantly lower. These findings suggest that self-fertilization gives rise to inbreeding depression associated with developmental deficits that are likely caused by expression of deleterious recessive mutations. Other examples of protogynous organisms include: The ultimate cause of

1600-507: A spectrum of different forms, which are characterized by the overlap between male and female reproductive function throughout an organism's lifetime: Furthermore, there are also species that reproduce as both sexes throughout their lifespans (i.e simultaneous hermaphrodites ), but shift their reproductive resources from male to female over time. Protandry occurs in a widespread range of animal phyla. In fact, protandrous hermaphroditism occurs in many fish, mollusks , and crustaceans , but

1680-417: A valued ornamental and medicinal plant, is so invasive as to have been declared a weed in subtropical forested areas of South Africa. Lauraceae flowers are protogynous , often with a complex flowering system to prevent inbreeding . The fruits are an important food source for birds, on which some Palaeognathae are highly dependent. Other birds that rely heavily on the fruit for their diets include members of

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1760-404: Is a more common form of sequential hermaphroditism in fish, especially when compared to protandry. As the animal ages, it shifts sex to become a male animal due to internal or external triggers, undergoing physiological and behavioral changes. In many fishes, female fecundity increases continuously with age, while in other species larger males have a selective advantage (such as in harems), so it

1840-467: Is also dependent on size: the smaller flowers are male while the larger flowers are both male and female. Typically in Arisaema species, small flowers only contain stamens, meaning they are males. Larger flowers can contain both stamen and pistils or only pistils, meaning they can be either hermaphrodites or strictly female. Striped maple trees ( Acer pensylvanicum ) have been shown to change sex over

1920-412: Is based on size, the female being the largest and the reproductive male being the second largest. The rest of the group is made up of progressively smaller males that do not breed and have no functioning gonads. If the female dies, in many cases, the reproductive male gains weight and becomes the female for that group. The largest non-breeding male then sexually matures and becomes the reproductive male for

2000-499: Is commonly referred to as the "walnut family". The delineation of what constitutes a family— or whether a described family should be acknowledged— is established and decided upon by active taxonomists . There are not strict regulations for outlining or acknowledging a family, yet in the realm of plants, these classifications often rely on both the vegetative and reproductive characteristics of plant species. Taxonomists frequently hold varying perspectives on these descriptions, leading to

2080-408: Is completely absent in terrestrial vertebrates. Protandrous fishes include teleost species in the families Pomacentridae , Sparidae , and Gobiidae . A common example of a protandrous species are clownfish , which have a very structured society. In the species Amphiprion percula , there are zero to four individuals excluded from breeding and a breeding pair living in a sea anemone . Dominance

2160-436: Is decreased with age, the latter seems to be rare in the field. An example of territoriality favoring protogyny occurs when there is a need to protect their habitat and being a large male is advantageous for this purpose. In the mating aspect, a large male has a higher chance of mating, while this has no effect on the female mating fitness. Thus, he suggests that female fecundity has more impact on sequential hermaphroditism than

2240-654: Is first male then female. It used to be thought that this reduced inbreeding , but it may be a more general mechanism for reducing pollen-pistil interference. Hermaphroditic fishes are almost exclusively sequential—simultaneous hermaphroditism is only known to occur in one species of fish, the Rivulid killifish Kryptolebias marmoratus . Additionally, Teleost fishes are the only vertebrate lineage where sequential hermaphroditism occurs. In general, protandrous hermaphrodites are animals that develop as males, but can later reproduce as females. However, protandry features

2320-483: Is hypothesized that the mating system can determine whether it is more selectively advantageous to be a male or female when an organism's body is larger. Protogyny is the most common form of hermaphroditism in fish in nature. About 75% of the 500 known sequentially hermaphroditic fish species are protogynous and often have polygynous mating systems. In these systems, large males use aggressive territorial defense to dominate female mating. This causes small males to have

2400-402: Is not fully supported. Backing has come from matK sequences of chloroplast genes while a questionable placement of Cassytha has been concluded from analysis of intergenetic spacers of chloroplast and nuclear genomes. Embryological studies also appear contradictory. One study by Heo et al. (1998) supports the subfamily. It found that Cassytha develops an ab initio cellular-type endosperm and

2480-485: Is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy . It is classified between order and genus . A family may be divided into subfamilies , which are intermediate ranks between the ranks of family and genus. The official family names are Latin in origin; however, popular names are often used: for example, walnut trees and hickory trees belong to the family Juglandaceae , but that family

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2560-404: Is poorly understood. This is partly due to its great diversity, the difficulty of identifying the species, and partly because of inadequate investment in taxonomic work. Recent monographs on small and medium-sized genera of Lauraceae (up to about 100 species) have revealed many new species. Similar increases in the numbers of species recognised in other larger genera are to be expected. Most of

2640-569: Is unique in the Lauraceae in that its members are parasitic vines . Most laurels are highly poisonous. The family has a worldwide distribution in tropical and warm climates. The Lauraceae are important components of tropical forests ranging from low-lying to montane . In several forested regions, Lauraceae are among the top five families in terms of the number of species present. The Lauraceae give their name to habitats known as laurel forests , which have many trees that superficially resemble

2720-722: The Genera Plantarum of George Bentham and Joseph Dalton Hooker this word ordo was used for what now is given the rank of family. Families serve as valuable units for evolutionary, paleontological, and genetic studies due to their relatively greater stability compared to lower taxonomic levels like genera and species. Protogynous In animals, the different types of change are male to female ( protandry or protandrous hermaphroditism ), female to male ( protogyny or protogynous hermaphroditism ), and bidirectional ( serial or bidirectional hermaphroditism ). Both protogynous and protandrous hermaphroditism allow

2800-424: The gonads or can change from one complete gonadal type to the other during their last life stage. In plants, individual flowers are called dichogamous if their function has the two sexes separated in time, although the plant as a whole may have functionally male and functionally female flowers open at any one moment. A flower is protogynous if its function is first female, then male, and protandrous if its function

2880-425: The matK chloroplast gene, as well as sequences of chloroplast and nuclear genomes, reveal close relationships between the two tribes. Embryological evidence does not support a clear division between the two tribes, either. Genera such as Caryodaphnopsis and Aspidostemon that share embryological characteristics with one tribe and wood and bark characteristics or inflorescence characteristics with another tribe blur

2960-553: The palaeontological succession and climate change that followed the breakups of the supercontinents. These genera include some of the best-known species of particular commercial value: Loss of habitat and overexploitation for such products has put many species in danger of extinction as a result of overcutting, extensive illegal logging , and habitat conversion. Conversely, some species, though commercially valuable in some countries, are regarded as aggressive invaders in other regions. For example, Cinnamomum camphora , though

3040-399: The Lauraceae are evergreen trees in habit . Exceptions include some two dozen species of Cassytha , all of which are obligately parasitic vines . The fruits of Lauraceae are drupes , one-seeded fleshy fruit with a hard layer, the endocarp , surrounding the seed. However, the endocarp is very thin, so the fruit resemble a one-seeded berry. The fruit in some species (particularly in

3120-408: The Lauraceae is not fully resolved. Multiple classification schemes based on a variety of morphological and anatomical characteristics have been proposed, but none are fully accepted. According to Judd et al. (2007), the suprageneric classification proposed by van der Werff and Richter (1996) is currently the authority. However, due to an array of molecular and embryological evidence that disagrees with

3200-404: The Lauraceae, though they may belong to other plant families such as Magnoliaceae or Myrtaceae . Laurel forests of various types occur on most continents and on many major islands. Although the taxonomy of the Lauraceae is still not settled, conservative estimates suggest some 52 genera worldwide, including 3,000 to 3,500 species. Compared to other plant families, the taxonomy of Lauraceae still

3280-604: The Tertiary strata of Europe and North America, but they virtually disappeared from central Europe in the Late Miocene . Because of their unusual fragility, the pollens of Lauraceae do not keep well and have been found only in relatively recent strata. Deciduous Lauraceae lose all of their leaves for part of the year depending on variations in rainfall. The leaf loss coincides with the dry season in tropical, subtropical, and arid regions. Laurel wilt disease, caused by

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3360-488: The age structures of the population. The size-advantage model predicts that sex change would only be absent if the relationship between size/age with reproductive potential is identical in both sexes. With this prediction one would assume that hermaphroditism is very common, but this is not the case. Sequential hermaphroditism is very rare and according to scientists this is due to some cost that decreases fitness in sex changers as opposed to those who do not change sex. Some of

3440-643: The benefits of large inflorescences from the consequences of geitonogamy and pollen discounting. Such a decoupling would provide a significant reproductive advantage through increased pollinator visitation and siring success. It has been demonstrated experimentally that dichogamy both reduced rates of self-fertilization and enhanced outcross siring success through reductions in geitonogamy and pollen discounting, respectively. The influence of inflorescence size on this siring advantage shows bimodal distribution, with increased siring success with both small and large display sizes. The duration of stigmatic receptivity plays

3520-574: The conversion of testosterone into oestradiol , which is irreversible. It has been discovered that the aromatase pathway mediates sex change in both directions in organisms. Many studies also involve understanding the effect of aromatase inhibitors on sex change. One such study was performed by Kobayashi et al. In their study they tested the role of estrogens in male three-spot wrasses ( Halichoeres trimaculatus ). They discovered that fish treated with aromatase inhibitors showed decreased gonodal weight, plasma estrogen level and spermatogonial proliferation in

3600-454: The division of these groups. All available evidence, except for inflorescence morphology and wood and bark anatomy, fails to support separate tribes Laureae and Perseeae. The tribe Cryptocaryeae is partially supported by molecular and embryological studies. Chloroplast and nuclear genomes support a tribal grouping that contains all the genera circumscribed by van der Weff and Richter (1996), as well as three additional genera. Partial support for

3680-769: The evolution of floral display size may represent a compromise between maximizing pollinator visitation and minimizing geitonogamy and pollen discounting (Barrett et al., 1994). Protandry may be particularly relevant to this compromise, because it often results in an inflorescence structure with female phase flowers positioned below male phase flowers. Given the tendency of many insect pollinators to forage upwards through inflorescences, protandry may enhance pollen export by reducing between-flower interference. Furthermore, this enhanced pollen export should increase as floral display size increases, because between-flower interference should increase with floral display size. These effects of protandry on between-flower interference may decouple

3760-407: The families Cotingidae , Columbidae , Trogonidae , Turdidae , and Ramphastidae , amongst others. Birds that are specialised frugivores tend to eat the whole fruit and regurgitate seeds intact, thereby releasing the seeds in favourable situations for germination ( ornithochory ). Some other birds that swallow the fruit pass the seed intact through their guts. Seed dispersal of various species in

3840-508: The family Labridae. Wrasses are found around the world in all marine habitats and tend to bury themselves in sand at night or when they feel threatened. In wrasses, the larger of a mating pair is the male, while the smaller is the female. In most cases, females and immature males have a uniform color while the male has the terminal bicolored phase. Large males hold territories and try to pair spawn, while small to mid-size initial-phase males live with females and group spawn . In other words, both

3920-405: The family Pomacentridae was gonochoristic (single-sexed), indicating that protandry evolved within the family. Therefore, because other families also contain protandrous species, protandry likely has evolved multiple times. Other examples of protandrous animals include: Protogynous hermaphrodites are animals that are born female and at some point in their lifespan change sex to male. Protogyny

4000-540: The family as a rank intermediate between order and genus was introduced by Pierre André Latreille in his Précis des caractères génériques des insectes, disposés dans un ordre naturel (1796). He used families (some of them were not named) in some but not in all his orders of "insects" (which then included all arthropods ). In nineteenth-century works such as the Prodromus of Augustin Pyramus de Candolle and

4080-595: The family however, occur pantropically in general lowland and Afromontane forest, and in Africa for example there are species endemic to countries such as Cameroon , Sudan , Tanzania , Uganda and Congo . Several relict species in the Lauraceae occur in temperate areas of both hemispheres. Many botanical species in other families have similar foliage to the Lauraceae due to convergent evolution , and forests of such plants are called laurel forest . These plants are adapted to high rainfall and humidity, and have leaves with

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4160-579: The family include these genera: These genera have traditionally been considered separate within Lauraceae, but have not been included in the most recent treatments: A laurel wreath , a round or horseshoe-shaped wreath made of connected laurel branches and leaves, is an ancient symbol of triumph in classical Western culture originating in Greek mythology , and is associated in some countries with academic or literary achievement. Family (biology) Family ( Latin : familia , pl. : familiae )

4240-492: The family is also carried out by monkeys , arboreal rodents , porcupines , opossums , and fishes . Hydrochory occurs in Caryodaphnopsis . The leaves of some species in the Lauraceae have domatia in the axils of their veins . The domatia are home to certain mites . Other lauraceous species, members of the genus Pleurothyrium in particular, have a symbiotic relationship with ants that protect and defend

4320-703: The genera Ocotea ) are partly immersed or covered in a cup-shaped or deep thick cupule , which is formed from the tube of the calyx where the peduncle joins the fruit; this gives the fruit an appearance similar to an acorn . In some Lindera species, the fruit have a hypocarpium at the base of the fruit. Because the family is so ancient and was so widely distributed on the Gondwana supercontinent , modern species commonly occur in relict populations isolated by geographical barriers, for instance on islands or tropical mountains. Relict forests retain endemic fauna and flora in communities of great value in inferring

4400-402: The group. Other protandrous fishes can be found in the classes clupeiformes , siluriformes , stomiiformes . Since these groups are distantly related and have many intermediate relatives that are not protandrous, it strongly suggests that protandry evolved multiple times. Phylogenies support this assumption because ancestral states differ for each family. For example, the ancestral state of

4480-453: The groupings, it is not fully accepted by the scientific community. Their classification is based on inflorescence structure and wood and bark anatomy. It divides Lauraceae into two subfamilies, Cassythoideae and Lauroideae. The Cassythoideae comprise a single genus, Cassytha , and are defined by their herbaceous, parasitic habit. The Lauroideae are then divided into three tribes: Laureae, Perseeae, and Cryptocaryeae. The subfamily Cassythoideae

4560-928: The huge amount of variation within the family poses a major challenge for developing a reliable classification. The adaptation of Lauraceae to new environments has followed a long evolutionary journey which has led to many specializations , including defensive or deterrent systems against other organisms. Phytochemicals in the Lauraceae are numerous and diverse. Benzylisoquinoline alkaloids include aporphines and oxoaporphines , as well as derivatives of morphinans . Essential oils include terpenoids , benzyl benzoates , allylphenols , and propenylphenols . Lignans and neolignans are present, along with S -methyl-5-O- flavonoids , proanthocyanidins , cinnamoylamides , phenylpyrroles, styryl pyrones , polyketides ( acetogenins ), furanosesquiterpenes , and germacranolidous , heliangolidous , eudesmanolidous and guaianolidous sesquiterpene lactones . Recent taxonomic revisions of

4640-531: The hypotheses proposed for the dearth of hermaphrodites are the energetic cost of sex change, genetic and/or physiological barriers to sex change, and sex-specific mortality rates. In 2009, Kazanciglu and Alonzo found that dioecy was only favored when the cost of changing sex was very large. This indicates that the cost of sex change does not explain the rarity of sequential hermaphroditism by itself. The size-advantage model also explains under which mating systems protogyny or protandry would be more adaptive. In

4720-461: The initial- and terminal-phase males can breed, but they differ in the way they do it. In the California sheephead ( Semicossyphus pulcher ), a type of wrasse, when the female changes to male, the ovaries degenerate and spermatogenic crypts appear in the gonads. The general structure of the gonads remains ovarian after the transformation and the sperm is transported through a series of ducts on

4800-568: The levels of periodic floods that drown competing plants which lack such adaptations. Paleobotanists have suggested the family originated some 174±32 million years ago (Mya), while others do not believe they are older than the mid- Cretaceous . Fossil flowers attributed to this family occur in Cenomanian clays (mid-Cretaceous, 90-98 Mya) of the Eastern United States ( Mauldinia mirabilis ). Fossils of Lauraceae are common in

4880-495: The opposite sex are already present. Sequential hermaphroditism in plants is the process in which a plant changes its sex during its lifetime. Sequential hermaphroditism in plants is very rare. There are less than 0.1% of recorded cases in which plant species entirely change their sex. The Patchy Environment Model and Size Dependent Sex Allocation are the two environmental factors which drive sequential hermaphroditism in plants. The Patchy Environment Model states that plants maximize

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4960-461: The organism to switch between functional male and functional female. Bidirectional hermaphrodites have the capacity for sex change in either direction between male and female or female and male, potentially repeatedly during their lifetime. These various types of sequential hermaphroditism may indicate that there is no advantage based on the original sex of an individual organism. Those that change gonadal sex can have both female and male germ cells in

5040-411: The other sex at about the same age, then siblings are highly likely to be the same sex at any given time. This should dramatically reduce the likelihood of inbreeding. Both protandry and protogyny are known to help prevent inbreeding in plants, and many examples of sequential hermaphroditism attributable to inbreeding prevention have been identified in a wide variety of animals. The proximate cause of

5120-474: The periphery of the gonad and oviduct . Here, sex change is age-dependent. For example, the California sheephead stays a female for four to six years before changing sex since all California sheephead are born female. Bluehead wrasses begin life as males or females, but females can change sex and function as males. Young females and males start with a dull initial-phase coloration before progressing into

5200-472: The rest of the family (with one exception) develops a nuclear-type endosperm. Kimoto et al. (2006) suggest Cassytha should be placed in the tribe Cryptocaryeae because it shares a glandular anther tapetum and an embryo sac protruding from the nucellus with other members of the Cryptocaryeae. The tribes Laureae and Perseeae are not well supported by any molecular or embryological studies. Sequences of

5280-575: The seventy-six groups of plants he recognised in his tables families ( familiae ). The concept of rank at that time was not yet settled, and in the preface to the Prodromus Magnol spoke of uniting his families into larger genera , which is far from how the term is used today. In his work Philosophia Botanica published in 1751, Carl Linnaeus employed the term familia to categorize significant plant groups such as trees , herbs , ferns , palms , and so on. Notably, he restricted

5360-402: The sex reversal process by being synthesized as Leydig cells replicate and differentiate. Thus, the synthesis of sex steroids coincides with gonadal remodeling, which is triggered by MMPs produced by germinal epithelial tissue. These results suggests that MMPs and changes in steroid levels play a large role in sequential hermaphroditism in teleosts. Sequential hermaphrodites almost always have

5440-431: The style of the female flower elongating, then later in the male phase the anthers shedding pollen. Historically, dichogamy has been regarded as a mechanism for reducing inbreeding . However, a survey of the angiosperms found that self-incompatible (SI) plants, which are incapable of inbreeding, were as likely to be dichogamous as were self-compatible (SC) plants. This finding led to a reinterpretation of dichogamy as

5520-415: The teleost Synbranchus marmoratus found that metalloproteinases (MMPs) were involved in gonadal remodeling. In this process, the ovaries degenerated and were slowly replaced by the germinal male tissue. In particular, the action of MMPs induced significant changes in the interstitial gonadal tissue, allowing for reorganization of germinal epithelial tissue. The study also found that sex steroids help in

5600-421: The temporal overlap between stigma and anthers within an inflorescence. Large inflorescences attract more pollinators, potentially enhancing reproductive success by increasing pollen import and export. However, large inflorescences also increase the opportunities for both geitonogamy and pollen discounting, so that the opportunity for between-flower interference increases with inflorescence size. Consequently,

5680-406: The testis as well as increased androgen levels. Their results suggest that estrogens are important in the regulation of spermatogenesis in this protogynous hermaphrodite. Previous studies have also investigated sex reversal mechanisms in teleost fish. During sex reversal, their whole gonads including the germinal epithelium undergoes significant changes, remodeling, and reformation. One study on

5760-673: The transfer of pollen between flowers of the same individual. In contrast to within-flower interference, geitonogamy necessarily involves the same processes as outcrossing: pollinator attraction, reward provisioning, and pollen removal. Therefore, between-flower interference not only carries the cost of self-fertilization ( inbreeding depression ), but also reduces the amount of pollen available for export (so-called "pollen discounting" ). Because pollen discounting diminishes outcross siring success, interference avoidance may be an important evolutionary force in floral biology. Dichogamy may reduce between-flower interference by reducing or eliminating

5840-482: The tree. Some Ocotea species are also used as nesting sites by ants, which may live in leaf pockets or in hollowed-out stems. Defense mechanisms that occur among members of the Lauraceae include irritant or toxic sap or tissues that repel or poison many herbivorous organisms. Trees of the family predominate in the world's laurel forests and cloud forests , which occur in tropical to mild temperate regions of both northern and southern hemispheres. Other members of

5920-467: The tribe is also attained from the matK sequences of chloroplast genes as well as embryology. Challenges in Lauraceae classification The knowledge of the species comprising the Lauraceae is incomplete. In 1991, about 25-30% of neotropical Lauraceae species had not been described. In 2001, embryological studies had only been completed on individuals from 26 genera yielding a 38.9% level of knowledge, in terms of embryology, for this family. Additionally,

6000-405: The two species, and while Ne was lower in the instant for the sex-changer, they were similar over a relatively short time horizon. The ability of these organisms to change biological sex has allowed for better reproductive success based on the ability for certain genes to pass down more easily from generation to generation. The change in sex also allows for organisms to reproduce if no individuals of

6080-440: The use of resources, if the combination of size and fitness for a certain sex is more beneficial, the plant will change to that sex. Evolutionarily, sequential hermaphrodites emerged as certain species obtained a reproductive advantage by changing their sex. Arisaema triphyllum (Jack in the pulpit) is a plant species which is commonly cited as exercising sequential hermaphroditism. As A. triphyllum grows, it develops from

6160-405: The use of their resources by changing their sex. For example, if a plant benefits more from the resources of a given environment in a certain sex, it will change to that sex. Furthermore, Size Dependent Sex Allocation outlines that in sequential hermaphroditic plants, it is preferable to change sexes in a way that maximizes their overall fitness compared to their size over time. Similar to maximizing

6240-549: The use of this term solely within the book's morphological section, where he delved into discussions regarding the vegetative and generative aspects of plants. Subsequently, in French botanical publications, from Michel Adanson 's Familles naturelles des plantes (1763) and until the end of the 19th century, the word famille was used as a French equivalent of the Latin ordo (or ordo naturalis ). In zoology ,

6320-517: The virulent fungal pathogen Raffaelea lauricola , a native of southern Asia , was found in the southeast United States in 2002. The fungus spreads between hosts via a wood-boring beetle, Xyleborus glabratus , with which it has a symbiotic relationship. Several Lauraceae species are affected. The beetle and disease are believed to have arrived in the US via infected solid wood packing material, and have since spread to several states. Classification within

6400-422: Was less likely to occur when the size advantage is stronger than other advantages. Warner suggests that selection for protandry may occur in populations where female fecundity is augmented with age and individuals mate randomly. Selection for protogyny may occur where there are traits in the population that depress male fecundity at early ages (territoriality, mate selection or inexperience) and when female fecundity

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