Tachigali versicolor
Encyclopedia
Tachigali versicolor or the suicide tree is a species of tree found from Costa Rica
to western Colombia
. It is monocarpic
, flowering only once before dying, which gives rise to its common name of the "suicide tree".
in Panama, they were observed to flower in 1970, 1974, 1978, 1983, 1984, 1989 and 1994. Despite the suicidal nature of their reproductive strategy they do not appear to divert any more nutrients into their one set of seeds than other similar trees. While apparently maladaptive, the strategy has been suggested to be effective at maintaining populations, as when the parent tree dies it creates a gap in the canopy
which the seedlings require to grow.
Flowering occurs between January and July, with individuals flowering for between 6 and 12 weeks. The fruits are large, wind dispersed
samara
s and they mostly fall within 100m of the parent tree. The seeds, which weigh around half a gram are predated
while still on the tree by parrot
s and bruchid beetles (Amblycerus tachygaliae) and once on the forest floor
by rodent
s, peccaries and fungi. The seeds lack dormancy and germinate in late April and early May, the seedlings are tolerant of shade and can survive for many years in the understorey while waiting for a gap in the canopy to form. Seedlings are more likely to survive growing under the canopy of other T. versicolor trees than under trees of a different species. For the first two months after germination, those that grow in the shade are more likely to survive because less grazing occurs in the shade. After two months those in light gaps are more likely to survive. Each tree produces around 50,000 seeds of which 30% germinate and 5% survive for more than two years. If light conditions change the seedlings are able to quickly adapt to the new conditions by growing new leaves that are especially adapted to capture the light level. Compared to other monocarpic trees that grow in similar environments, T. versicolor has relatively high seed mass, dispersal capability, photosynthetic flexibility and seedling survival in the shaded understory in the first year of growth.
they depend on to digest leaves.
family it has a symbiotic relationship with nitrogen fixing
bacteria. The bacteria found in the trees nodules are from the Bradyrhizobium
genus.
Costa Rica
Costa Rica , officially the Republic of Costa Rica is a multilingual, multiethnic and multicultural country in Central America, bordered by Nicaragua to the north, Panama to the southeast, the Pacific Ocean to the west and the Caribbean Sea to the east....
to western Colombia
Colombia
Colombia, officially the Republic of Colombia , is a unitary constitutional republic comprising thirty-two departments. The country is located in northwestern South America, bordered to the east by Venezuela and Brazil; to the south by Ecuador and Peru; to the north by the Caribbean Sea; to the...
. It is monocarpic
Monocarpic
Monocarpic plants are those that flower, set seeds and then die. Other terms with the same meaning are hapaxanth and semelparous. The term was first used by Alphonse de Candolle....
, flowering only once before dying, which gives rise to its common name of the "suicide tree".
Reproduction
Tachigali versicolor reproduces only once in its lifetime once the trees are mature. Within a year of flowering the tree rapidly dies and falls over. The trait was first noticed by Robin Foster in 1970, while working in Panama. Carlos Fonseca reported that another species in the genus, Tachigali myrmecophila is also monocarpic. The age at which they reproduce is unknown, however, and growth rates vary widely depending on the amount of light that the trees grow in. Reproduction (and death) has been observed to occur in a four to six year cycle; if flowering occurs one year then it will not occur for the next three to five years. When studied on Barro Colorado IslandBarro Colorado Island
Barro Colorado Island is located in the man-made Gatun Lake in the middle of the Panama Canal. The island was formed when the waters of the Chagres River were dammed to form the lake. When the waters rose, they covered a significant part of the existing rainforest, and the hilltops remained as...
in Panama, they were observed to flower in 1970, 1974, 1978, 1983, 1984, 1989 and 1994. Despite the suicidal nature of their reproductive strategy they do not appear to divert any more nutrients into their one set of seeds than other similar trees. While apparently maladaptive, the strategy has been suggested to be effective at maintaining populations, as when the parent tree dies it creates a gap in the canopy
Gap (ecology)
In forest ecology, a treefall gap is an opening in the forest canopy structure devoid of large trees. Gaps are formed after large trees die and fall which allows the regrowth trees and other plants as the shade is removed.-References:...
which the seedlings require to grow.
Flowering occurs between January and July, with individuals flowering for between 6 and 12 weeks. The fruits are large, wind dispersed
Seed dispersal
Seed dispersal is the movement or transport of seeds away from the parent plant. Plants have limited mobility and consequently rely upon a variety of dispersal vectors to transport their propagules, including both abiotic and biotic vectors. Seeds can be dispersed away from the parent plant...
samara
Samara (fruit)
A samara is a type of fruit in which a flattened wing of fibrous, papery tissue develops from the ovary wall. A samara is a simple dry fruit and indehiscent . It is a winged achene...
s and they mostly fall within 100m of the parent tree. The seeds, which weigh around half a gram are predated
Seed predation
Seed predation, often referred to as granivory, is a type of plant-animal interaction in which granivores feed on the seeds of plants as a main or exclusive food source, in many cases leaving the seeds damaged and not viable...
while still on the tree by parrot
Parrot
Parrots, also known as psittacines , are birds of the roughly 372 species in 86 genera that make up the order Psittaciformes, found in most tropical and subtropical regions. The order is subdivided into three families: the Psittacidae , the Cacatuidae and the Strigopidae...
s and bruchid beetles (Amblycerus tachygaliae) and once on the forest floor
Forest floor
The forest floor, also called detritus, duff and the O horizon, is one of the most distinctive features of a forest ecosystem. It mainly consists of shed vegetative parts, such as leaves, branches, bark, and stems, existing in various stages of decomposition above the soil surface...
by rodent
Rodent
Rodentia is an order of mammals also known as rodents, characterised by two continuously growing incisors in the upper and lower jaws which must be kept short by gnawing....
s, peccaries and fungi. The seeds lack dormancy and germinate in late April and early May, the seedlings are tolerant of shade and can survive for many years in the understorey while waiting for a gap in the canopy to form. Seedlings are more likely to survive growing under the canopy of other T. versicolor trees than under trees of a different species. For the first two months after germination, those that grow in the shade are more likely to survive because less grazing occurs in the shade. After two months those in light gaps are more likely to survive. Each tree produces around 50,000 seeds of which 30% germinate and 5% survive for more than two years. If light conditions change the seedlings are able to quickly adapt to the new conditions by growing new leaves that are especially adapted to capture the light level. Compared to other monocarpic trees that grow in similar environments, T. versicolor has relatively high seed mass, dispersal capability, photosynthetic flexibility and seedling survival in the shaded understory in the first year of growth.
Ecology
Leaf cutter ants do not harvest the leaves of the suicide tree, presumably because the leaves contain anti-fungal chemicals which would kill the fungusAnt-fungus mutualism
Ant-fungus mutualism is a symbiosis seen in certain ant and fungal species, where ants actively cultivate fungus much like humans farm crops as a food source. In some species, the ants and fungi are dependent on each other for survival. The leafcutter ant is a well known example of this symbiosis...
they depend on to digest leaves.
Symbionts
As a member of the FabaceaeFabaceae
The Fabaceae or Leguminosae, commonly known as the legume, pea, or bean family, is a large and economically important family of flowering plants. The group is the third largest land plant family, behind only the Orchidaceae and Asteraceae, with 730 genera and over 19,400 species...
family it has a symbiotic relationship with nitrogen fixing
Nitrogen fixation
Nitrogen fixation is the natural process, either biological or abiotic, by which nitrogen in the atmosphere is converted into ammonia . This process is essential for life because fixed nitrogen is required to biosynthesize the basic building blocks of life, e.g., nucleotides for DNA and RNA and...
bacteria. The bacteria found in the trees nodules are from the Bradyrhizobium
Bradyrhizobium
Bradyrhizobium is a genus of Gram-negative soil bacteria, many of which fix nitrogen. Nitrogen fixation is an important part of the nitrogen cycle. Plants cannot use atmospheric nitrogen they must use nitrogen compounds such as nitrates....
genus.
Uses
Indigenous people in the Amazon basin use an extract of the tree to treat fungal skin infections and it is also used as timber.External links
- Images of Tachigali versicolor at Discover Life