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trichocereus lineage/common ancestor

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just a thought bubble,

is there some generally accepted trichocereus (or even any cacti) lineage, or a common ancestor? i.e. like we can trace human evolution through homo erectus through to h. sapiens etc. is there a generally accepted ancestor of modern trichos like we see? or is this more or less impossible?

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Oh man.

Big question.

So from my own perspective, I would theorise that at one stage there was simply a small genetic variance of a single columnar cactus... then from that variance, perhaps cereus, tricho, blue myrtle etc all branched via certain isolated geographic pockets.

If I were then to pick the genotype of the trichocereus branch, i would surmise it to be either a rough tescheckii or a many ribbed peruvianus form. But basically, something with spines, as many of the old-world creatures that used to exist in South America would otherwise have demolished the population via nutritional source - i.e., i could see a smooth San Pedro being a tasty snack for one of those colossal vegetarian bears, etc.. :)

But otherwise, there is honestly no way we can really tell, unless someone were to do an extensive demographic and DNA study to figure out the recession of particular genes - or unless there was a fossil specimen found, and we could match the genetic structure strand by strand... but yeah can't see that happening any time soon, really..

In any event, in a recent cacti thread, Ms Smith seemed to be agreeing with the assumed consensus that anything after the original genotype was likely a clusterfuck of an Homo Sapiens influenced demographic.

...It sure is fun to theorise though!!! :)

Edited by hunnicutt
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I believe Pereskiopsis or something like it is the common ancestor of cactus, which was a leafy plant that slowly morphed to handle drier and harsher conditions. The full leaves on the Pereskiopsis are the ancestral feature in most cactus the leaves are very small indeed.

Actually a quick Google search identifies Pereskia as the ancestor, or something similar.

A quick Google search also reveals it's too complicated for me at this hour!

Abstract from:

Basal cactus phylogeny: implications of Pereskia (Cactaceae) paraphyly for the transition to the cactus life form1
  1. Erika J. Edwards2,4,
  2. Reto Nyffeler3 and
  3. Michael J. Donoghue2

The cacti are well-known desert plants, widely recognized by their specialized growth form and essentially leafless condition. Pereskia, a group of 17 species with regular leaf development and function, is generally viewed as representing the “ancestral cactus,” although its placement within Cactaceae has remained uncertain. Here we present a new hypothesis of phylogenetic relationships at the base of the Cactaceae, inferred from DNA sequence data from five gene regions representing all three plant genomes. Our data support a basal split in Cactaceae between a clade of eight Pereskia species, centered around the Caribbean basin, and all other cacti. Two other Pereskia clades, distributed mostly in the southern half of South America, are part of a major clade comprising Maihuenia plus Cactoideae, and Opuntioideae. This result highlights several events in the early evolution of the cacti. First, during the transition to stem-based photosynthesis, the evolution of stem stomata and delayed bark formation preceded the evolution of the stem cortex into a specialized photosynthetic tissue system. Second, the basal split in cacti separates a northern from an initially southern cactus clade, and the major cactus lineages probably originated in southern or west-central South America.

Evolution of columnar cactus came down the track i assume through the process of speciation we got the diversity seen today as for all plants. I'm pretty sure the emergence of the Panama land bridge was a critical influence in this as it allowed cactus to move south to north through the americas.

Wikipedia entry for Cactus excerpt:

Based on the phylogeny of the cacti, the earliest diverging group (Pereskia clade A) may have originated in Central America and northern South America, whereas the caulocacti, those with more-or-less succulent stems, evolved later in the southern part of South America, and then moved northwards.[32] Core cacti, those with strongly succulent stems, are estimated to have evolved around 25 million years ago.[33] A possible stimulus to their evolution may have been uplifting in the central Andes, some 25–20 million years ago, which was associated with increasing and varying aridity.[32] However, the current species diversity of cacti is thought to have arisen only in the last 10–5 million years (from the late Miocene into the Pliocene). Other succulent plants, such as the Aizoaceae in South Africa, the Didiereaceae in Madagascar and the genus Agave in the Americas, appear to have diversified at the same time, which coincided with a global expansion of arid environments.[33]

The same process that created a diversity of plants anywhere (soil chemistry, topographical barriers, climate change, relationships with animals etc. etc.) would have diversified the cacti. The ancestor of the Trichs in there somewhere, I wonder what his chemical makeup was then, but it takes time to learn magic!

Edited by Micromegas
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Great thread, but regarding a subject of which I am far too unfamiliar. My own assumptions regarding Trichocereus have nothing to do with such a vast lineage, and are restricted purely to thoughts regarding the plants of Huarochiri being progenitors to T. pachanoi and the like.


Edited by M S Smith

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This is a huge Topic and DNA Testing only just begun for cacti.

And like Micromegas already mentioned correctly, Pereiskia and other leaved cacti are basically the Ancestors of Cacti as we know them today.

Edited by Evil Genius

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