Hi ICANT, that's a little jumbled, especially at the end.
Mutation Gene Flow Genetic Drift + 3.8 billion years = Macroevolution Natural Selection
Is supposed to be:
quote:
Mutation
Gene Flow
Genetic Drift
Natural Selection + 3.8 billion years = Macroevolution
Note that there is no process present in that equation that is not in microevolution except the longer span of time: macroevolution is an accumulation of microevolution, as they say just before that:
quote:
The basic evolutionary mechanismsmutation, migration, genetic drift, and natural selectioncan produce major evolutionary change if given enough time.
The word "can" is there because they don't have to, it is just as possible that some cyanobacteria remain happily as cyanobacteria after all that time.
I think you are reading too much emphasis into the word "transformation" (and personally I don't think they should have used it - "transition" would be better and more descriptive of what is going on, as "transitional" fossils are understood), as it gives the impression of individual organisms morphing into new forms.
quote:
Macroevolution refers to evolution of groups larger than an individual species.
This occurs by the simple formation of nested hierarchies with descent from common ancestors after speciation events: a species is a breeding population, when speciation occurs there is no longer a single species, but two (or more) and this is the generation of genera. Likewise when further speciation occurs, the genera become families. It is easier to envisage with clades, imho, as there is less confusion of what the different branches are - they are just lineages of descent from the common ancestor populations.
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At the top we have a single ancestor species population, at the bottom we have a "larger" group of descendant species, all related by common ancestry.
When we "zoom in" to a single species we can see evolution in process, as the species undergoes the change in proportions of hereditary traits in breeding population from generation to generation in response to ecological opportunities.
When we "zoom out" we see the effects of continual evolution in all species through time, we see specieation and increased diversity, we see the formation of nested hierarchies, and we see the formation of "groups larger than an individual species" that are related by descent from common ancestor populations.
This is macroevolution, and it has been observed.
In the process of this macroevolution the different branches are "transformed" generation by generation by microevolution until at the end they are different appearing than the ancestor population.
quote:
Macroevolution encompasses the grandest trends and transformations in evolution, such as the origin of mammals and the radiation of flowering plants. Macroevolutionary patterns are generally what we see when we look at the large-scale history of life.
This is where I think you go wrong in how you read what they are saying.
If we take the evolution of mammals as an example:
You can start here at REPTILOMORPHA:
Palaeos: Page not foundReptiliomorpha - Wikipedia
quote:
Kingdom: Animalia
Phylum: Chordata
Subphylum: Vertebrata
Superclass: Tetrapoda
Class: Amphibia sensu lato
Subclass: Labyrinthodontia
Superorder: Reptiliomorpha
Reptiliomorpha refers to reptile-like amphibians and the amniotes which evolved from them.
University of Bristol paleontologist Professor Michael J. Benton (2000, 2004) gives the following characteristics for the Reptiliomorpha:
• narrow premaxillae (less than half the skull width)
• vomers taper forward
• phalangeal formulae (number of joints in each toe) of foot 2.3.4.5.4—5
All descendants of reptiliomorphs are still reptiliomorphs.
SYNAPSIDA are descendants of reptiliomorphs:
Palaeos: Page not foundSynapsid - Wikipedia
quote:
Kingdom: Animalia
Phylum: Chordata
Subphylum: Vertebrata
Infraphylum: Gnathostomata
Superclass: Tetrapoda
(unranked) Amniota
Class: Reptilia
Subclass: Synapsida
Synapsids ('fused arch'), also known as theropsids ('beast face'), are a class of animals that includes mammals and everything closer to mammals than to other living amniotes.[1] The non-mammalian members are described as mammal-like reptiles in classical systematics,[2][3] but are referred to as "stem-mammals" or "proto-mammals" under cladistic terminology.[4] Synapsids evolved from basal amniotes and are one of the two major groups of the later amniotes, the other major group being the sauropsids (reptiles and birds).
Synapsids are characterized by having differentiated teeth. These include the canines, molars, and incisors. The trend towards differentiation is found in some labyrinthodonts and early anapsid reptilians in the form of enlargement of the first teeth on the maxilla, forming a form of proto-canines. This trait was subsequently lost in the Sauropsid line, but developed further in the synapsids. Early synapsids could have 2 or even 3 enlarged "canines", but in the therapsids, the pattern had settled to one canine in each upper jaw half. The lower canines developed later.
Most paleontologists hold fossilized jaw remains to be the distinguishing feature used to classify synapsids and reptiles. The jaw transition is a good classification tool as most other fossilized features that make a chronological progression from a reptile-like to a mammalian condition follow the progression of the jaw transition. The mandible, or lower jaw, consists of a single, tooth-bearing bone in mammals (the dentary), whereas the lower jaw of modern and prehistoric reptiles consists of a conglomeration of smaller bones (including the dentary, articular, and others).
All descendants of synapsids are still synapsids.
THERAPSIDA are descendants of synapsids:
Palaeos: Page not foundTherapsid - Wikipedia
quote:
Kingdom: Animalia
Phylum: Chordata
Subphylum: Vertebrata
Class: Synapsida
Order: Therapsida *
Therapsida is a group of synapsids that includes mammals and their immediate evolutionary ancestors. Other than the mammals, all lineages of the therapsids are extinct, with the last known non-mammalian therapsids dying out in the Early Cretaceous period (146 Ma to 100 Ma).
Therapsids' temporal fenestrae are larger than those of the pelycosaurs. The jaws of therapsids are more complex and powerful, and the teeth are differentiated into frontal incisors for nipping, large lateral canines for puncturing and tearing, and molars for shearing and chopping food. Their legs are positioned more vertically beneath their bodies than are the sprawling legs of reptiles and pelycosaurs.
All descendants of therapsids are still therapsids.
CYNODONTIA are descendants of therapsids:
Palaeos: Page not foundCynodont - Wikipedia
quote:
Kingdom: Animalia
Phylum: Chordata
Class: Synapsida
Order: Therapsida
Suborder: Cynodontia
Cynodontia or cynodonts ("dog teeth") are a taxon of therapsids endemic to all seven continents beginning during the Early Triassic 256 Ma.[1] This taxon includes modern mammals and their extinct close relatives. They were one of the most diverse groups of therapsids. They are named after their dog-like teeth.
Cynodonts have nearly all the characteristics of mammals. Their teeth were fully differentiated, the braincase bulged at the back of the head, and many of them walked in an upright manner. Cynodonts still laid eggs, as all Mesozoic proto-mammals probably did. Their temporal fenestrae were much larger than in its ancestors, and the widening of the zygomatic arch allowed for more robust jaw musculature supporting the evidence of a more mammal-like skull. They also have the secondary palate that other primitive therapsids lacked, except the therocephalians, who were the closest relatives of cynodonts. Their dentary was the largest bone in their lower jaw, as other smaller bones moved into the ears. They were probably warm-blooded, and covered in hair.
All descendants of cynodonts are still cynodonts.
MAMMALIFORMES are descendants of cynodonts:
Palaeos: Page not foundMammaliaformes - Wikipedia
quote:
Kingdom: Animalia
Phylum: Chordata
Subphylum: Vertebrata
(unranked): Amniota
Class: Synapsida
(unranked): Mammaliaformes
Mammaliaformes ("mammal-shaped") is a clade that contains the mammals and their closest extinct relatives. Phylogenetically it is defined as a clade including the most recent common ancestor of Sinoconodon, morganuconodonts, docodonts, Monotremata, Marsupialia, Placentalia, extinct members of this clade, and all of its descendants.
Early mammaliforms were generally shrew-like in appearance and size, and most of their distinguishing characteristics were internal. In particular, the structure of the mammaliform (and mammal) jaw and arrangement of teeth is nearly unique. Instead of having many teeth that are frequently replaced, mammals have one set of baby teeth and later one set of adult teeth which fit together precisely.
Mammaliforms have several common structures. Most importantly, mammaliforms have highly specialized molars, with cusps and flat regions for grinding food. This system is also unique to mammals, although it seems to have evolved convergently in pre-mammals multiple times.
Lactation and fur, along with other characteristically mammalian features, are also thought to characterize the Mammaliaformes, but these traits are difficult to study in the fossil record. The fossilized remains of Castorocauda lutrasimilis are a unique exception.
All descendants of mammaliaformes are still mammaliaformes.
MAMMALS are descendants of mammaliaformes:
Palaeos: Page not foundMammal - Wikipedia
quote:
Kingdom: Animalia
Phylum: Chordata
Subphylum: Vertebrata
Class: Mammalia
Mammals (formally Mammalia) are a class of vertebrate, air-breathing animals whose females are characterized by the possession of mammary glands while both males and females are characterized by sweat glands, hair and/or fur, three middle ear bones used in hearing, and a neocortex region in the brain.
Living mammal species can be identified by the presence of sweat glands, including those that are specialized to produce milk. However, other features are required when classifying fossils, since soft tissue glands and some other features are not visible in fossils. Paleontologists use a distinguishing feature that is shared by all living mammals (including monotremes), but is not present in any of the early Triassic synapsids: mammals use two bones for hearing that were used for eating by their ancestors. The earliest synapsids had a jaw joint composed of the articular (a small bone at the back of the lower jaw) and the quadrate (a small bone at the back of the upper jaw). Most reptiles including lizards, crocodilians, dinosaurs (and their descendants the birds) use this system, as did non-mammalian synapsids such as therapsids. Mammals have a different jaw joint, however, composed only of the dentary (the lower jaw bone which carries the teeth) and the squamosal (another small skull bone). In mammals the quadrate and articular bones have become the incus and malleus bones in the middle ear.
Mammals also have a double occipital condyle: they have two knobs at the base of the skull which fit into the topmost neck vertebra, and other vertebrates have a single occipital condyle.
All descendants of mammals are still mammals.
THERIA are descendants of mammals:
Palaeos: Page not foundTheria - Wikipedia
quote:
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Subclass: Theria
Theria (pronounced /ˈθɪərɪə/, from the Greek θηρίον, wild beast) is a subclass of mammals[2] that give birth to live young without using a shelled egg, including both eutherians (placental mammals) and metatherians (marsupials and their ancestors).
All descendants of therians are still therians.
EUTHERIA are descendants of therians:
Palaeos: Page not foundEutheria - Wikipedia
quote:
Eutheria (Greek: "true beasts") are a group of mammals consisting of placental mammals plus all extinct mammals that are more closely related to living placentals (such as humans) than to living marsupials (such as kangaroos). They are distinguished from non-eutherians by various features of the feet, ankles, jaws and teeth. One of the major differences between placental and non-placental eutherians is that placentals lack epipubic bones, which are present in all other fossil and living mammals.
All descendants of eutherians are still eutherians (which are still therians, which are still mammals, which are still mammaliaformes, which are still cynodonts, which are still therapsids, which are still synapsids, which are still reptiliomorphs).
So we have gone from reptilian ancestors to placental mammals (which includes you and me and bears, but not alligators and kangaroos). In the process we see:
- the jaw is transformed from a three bone structure to a single bone structure,
- the teeth are transformed into different types,
- the skull bones are transformed to create arches,
- etc etc etc
But none of these
transformations occur in a single species, or in a time frame that a typical life-span human could observe directly, they occur over geological time frames, and yet each stage is observed, each transition has a beginning stage, intermediate stages and final stages, and these stages are found in the fossil record. Thus the
transformation (transition) of one ancestral form into a quite different modern form is observed in pieces, like the frozen images in a movie film, each picture frozen in mid action, and only when you run the film through the projector do you see the motion, the transformation, the transition in time.
Just because we cannot see\observe\document large scale transitions in real time does not mean that we can see\observe\document the evidence of large scale transitions that have occurred.
Enjoy
... I have been very involved with one of my members that had terminal cancer ...
Thank you for doing what you can. Certainly I can understand how much just a little help is appreciated.
Edited by RAZD, : clrty
Edited by RAZD, : reworded bits
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